Report on south asian integrated water management imperative

1
Regional Implications of Water Resources
Management Interventions in South Asia
Mashfiqus Salehin
Anisul Haque
M. Shahjahan Mondal
Institute of water and Flood Management
Bangladesh University of Engineering and Technology
And
M. Anowar Hossain
ActionAid Bangladesh
December 2007
Prepared for
Action-Aid

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Table of Contents
Page No.
LIST OF TABLES iii
LIST OF FIGURES iv
EXECUTIVE SUMMARY
Chapter 1 Introduction 1
1.1 Background 1
1.2 Aim of the study
1.3 Structure of the report
Chapter 2 GBM Basins – Water, Land, and People
2.1 Introduction
2.2 GBM – three separate basins
2.3 GBM basins characteristics
2.3.1 The Ganges basin
2.3.2 The Brahmaputra Basin
2.3.3 The Meghna Basin
2.4 People of the basins
2.5 Cultural and religious importance of water
2.6 Major Water resources management issues
2.6.1 Water management issues in Nepal
2.6.2 Water management issues in India
2.6.3 Water management issues in Bangladesh
2.6.4 Water management issues in Bhutan
Chapter 3 Climate Change Threat to
Regional Water Resources Systems
3.1 Bangladesh
3.2 India
3.3 Nepal
Chapter 4 Water Resources Development Issues
4.1 Introduction
4.2 Augmentation of dry season flow
4.3 Flood management
4.4 Hydropower Development
4.5 Water quality
4.6 Inland navigation
4.7 Bilateralism vs. multilateralism
4.8 Basin-wide management
Chapter 5 Water Management Policies
5.1 Introduction
5.2 Comparison of water policies
5.2.1 Water Policy of India
5.2.2 Water Policy of Bangladesh
5.2.3 Water Management and Strategic Plan of Nepal
5.2.4 Water Policy of Bhutan

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Chapter 6 Regional Water Demand and Availability
6.1 Regional Water Demand
6.1.1 Introduction
6.1.2 Water demand in the GBM Basin within Bangladesh
6.1.3 Water demand in the GBM Basin within India
6.1.4 Water demand in Nepal
6.1.5 Water demand in Bhutan
6.2 Regional Water Availability
6.2.1 Introduction
6.2.2 Water availability in the GBM Basin within Bangladesh
6.2.3 Water availability in the GBM Basin within India
6.2.4 Water availability in Nepal
6.2.5 Water availability in Bhutan
6.3 Further Discussions
Chapter 7 History of Regional Cooperation
7.1 Introduction
7.2 Indo-Nepal cooperation
7.2.1 Sarada Agreement (1920)
7.2.2 Kosi river agreement (1954)
7.2.3 Gandak agreement (1959)
7.2.4 Mahakali treaty (1996)
7.2.5 Further discussion
7.3 Bangladesh-India cooperation
7.3.1 Ganges water sharing agreement 1977
7.3.2 MoUs
7.3.2 The Ganges Treaty 1996
7.3.4 No progress on other rivers including Teesta
7.4 Inter-state cooperation in India
Chapter 8 Indian Plan of River Linking
8.1 Introduction
8.2 River Linking Project
8.2.1 Context of the plan
8.2.2 Inter-basin water transfer plan
8.2.3 Claimed future benefits
8.2.4 Criticisms within India
8.2.5 Concerns of Nepal
8.2.6 Concerns of Bangladesh
Chapter 9 Development and Codification of
International Water Law
9.1 Introduction
9.2 Theories and doctrines of International Law
9.2.1 Absolute territorial sovereignty
9.2.2 Absolute territorial integrity
9.2.3 Doctrine of prior appropriation
9.2.4 Limited territorial sovereignty
9.2.5 Equitable and reasonable utilization
9.2.6 Obligation not to cause significant harm

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9.3 The Helsinki Rules 1966
9.4 UN Convention on Non-Navigational uses of
International Watercourses
9.5 International water law in the context of South Asia
9.6 Legal context of river link project
Chapter 10 Conflicts and Cooperation:
Experiences from Other Regions
10.1 Statistics of basins
10.2 Conflicts vs. cooperation
10.3 Importance of resilient institutions
10.4 Crisis prevention against post-crisis conflict resolution
10.5 The issue of equitable water allocation
10.6 Equitable distribution of benefits
10.7 Development in Water sharing agreements
10.7.1 Indus Water Treaty
10.8 Basin level transboundary water management
10.8.1 Mekong river commission
10.8.2 Nile Basin Initiative
10.9 10.9 Further discussions
References
Appendix-1 Convention on the Law of the Non-navigational Uses of
International Watercourses 1997

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LIST OF TABLES
Page No.
Table 2.1 Catchment areas of the GBM basins 19
Table 2.2 Table 2.2 Some salient details of the GBM region 22
Table 2.3 Important socio-economic parameters of major basin countries 22
Table 3.1 Degree of impacts of climate change on different sector 24
Table 4.1 Identified hydropower potential in Nepal 25
Table 6.1 Past and future water withdrawals and resources of the GBM
countries
26
Table 6.2 Annual fresh water withdrawals in some Asian countries 31
Table 6.3 Total water requirements in the GDA during the dry season 34
Table 6.4 Total water requirements in the BDA during the dry season 44
Table 6.5 Urban and rural population projections of India 46
Table 6.6 Estimated water demands for various uses in India 47
Table 6.7 Agricultural land and its use in the GBM states of India 49
Table 6.8 Percentage of the area of the Ganges basin within India 74
Table 6.9 The extent of cultivable area in the Ganges basin within India 77
Table 6.10 Percentage of the area of the Brahmaputra basin within India 80
Table 6.11 Percentage of Meghna basin area within India 81
Table 6.12 The extent of cultivable areas in the combined Brahmaputra
and Meghna basins
84
Table 6.13 Water withdrawals in the GBM basins within India 85
Table 6.14 Estimates of long-term EFR volumes at river basin outlets for
different Environmental Classes obtained using FDC shifting
and DRM
89
Table 6.15 Land-use within Nepal 90
Table 6.16 Gross water availability in Bangladesh
Table 6.17 Groundwater potential in GBM States and Union Territories of

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India
Table 6.18 Water resources (Mm3) of the GBM basins within India
Table 8.1 Claimed benefits of India‟s river linking plan

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LIST OF FIGURES
Page No.
Figure 1.1 GBM basins and river systems of Bangladesh 6
Figure 2.1 The Ganges basin and its river system 6
Figure 2.2 Schematic of the Ganges river system showing flow
contributions of tributaries
8
Figure 2.3 The Brahmaputra basin and its river system 10
Figure 2.4 Schematic of Brahmaputra river system showing flow
contributions of tributaries
11
Figure 2.5 The Meghna basin and its river system 12
Figure 2.6 Population in three major basin countries 14
Figure 2.7 Temporal distribution of rainfall in India 15
Figure 2.8 Spatial distribution of rainfall in India 18
Figure 2.9 Map of India showing different states 21
Figure 2.10 Surface runoffs in some Indian rivers 23
Figure 2.11 Average monthy rainfall distribution 25
Figure 2.12 Isohyetal pattern of average annual rainfall 28
Figure 2.13 Spatial distribution of average annual maximum, average
annual and average annual minimum discharge in major and
medium rivers
30
Figure 2.14 Flood prone areas in Bangladesh 38
Figure 2.15 Salinity intrusions in the southwest region of Bangladesh 43
Figure 4.1 Locations of dam sites in Nepal 45
Figure 4.2 Growth of flood control projects and variability of annually
flooded area
51
Figure 4.3 Flood forecasting in Bangladesh 54
Figure 6.1 Decade-wise water demand in the GDA (excluding coastal
regions)
55
Figure 6.2 Decade-wise water demand in the GDA (including coastal
regions)
57

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Figure 6.3 Decadal distribution of estimated water demand for the BDA 58
Page no.
Figure 7.1 Impact of Ganges water sharing agreements on the average
flow during first decades of February to April at Hardinge
Bridge
59
Figure 8.1 India‟s river link project 60
Figure 8.2 Himalayan component of river link project 62
Figure 8.3 Peninsular component of river link project 62
Figure 8.4 Mean annual flow of important tributaries of Ganges 63
Figure 10.1 Indus River Basin
Figure 10.2 Mekong River Basin
Figure 10.3 Nile River Basin

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Chapter 1
Introduction
1.1 Background
Rivers are an essential natural resource closely linked to a country‟s well being and economic
success. But rivers ignore political boundaries, and competition over the water resources, and
sharing of water of transboundary rivers among riparian nations has become a cause of major
concern in different parts of the globe for quite sometime. The issue in the recent decades
has been transformed into a source of international tensions and disputes resulting in strained
relationships between riparian nations. One of the most well-known conflicts in the world is
that in the basins of the Ganges, the Brahmaputra and the Meghna in the South Asian
subcontinent. Other widely known conflicts include sharing of water of the international
rivers, like the Tigris, Euphrates and Jordan in the Middle East, the Nile in Northern Africa,
and the Mekong in South-East Asia. Integrating international cooperation and conflict
resolution into the water management of transboundary Rivers has therefore become an
important issue in water resources management and hydropolitics.
The system of Ganges-Brahmaputra-Meghna (GBM) basins (see Figure 1.1) is made up of
the catchment areas, with a total drainage area of 1.75 million square kilometers, of three
major river systems that flow through India, Nepal, Bhutan, the Tibet region of China, and
Bangladesh. This huge system is second only to the Amazon, with an annual discharge of
1,350 billion cubic meters (bcm), of which the Ganges contributes about 500 bcm, the
Brahmaputra 700 bcm and the Meghna 150 bcm. About 91 per cent of flows in Bangladesh
enter from upstream catchments in India (Rashid, 1991). The entire volume of the GBM
river systems discharge into the Bay of Bengal through a single outlet at Lower Meghna in
Bangladesh. Also, of the 57 rivers which enter Bangladesh from across the borders, 54 of
them are from India (Figure 1.1). Hence, the transboundary water management concerns in
Bangladesh are perhaps greater than in any other countries of the world.
The three major rivers have always played a critical role in shaping the sustenance of live,
living and the environment, their roles perhaps much more than most parts of the world.
Rivers are major producers of hydropower, especially in the upland areas, and the main
sources of fisheries, and provide a very important means of transportation. The livelihood
activities of a large group of poor people are dependent upon the navigation along the water
courses for carrying agricultural goods. However, the river systems exhibit wide variations
between peak and lean flows as major part of the basin belongs to the monsoon region,
where 80%-90% of annual rainfall is concentrated in 4-5 months of South-West monsoon,

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Figure 1.1: GBM basins and river systems of Bangladesh

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while there is a general scarcity of water in the dry season. The availability of water is also
quite variable in space. Almost every year during monsoon about 27% and nearly 60% of the
GBM basin lying in India and Bangladesh respectively experience flood. Normal floods have
a good number of beneficial effects, including increase in floodplain soil fertility,
replenishment of water bodies (e.g. beels, haors) and hence nourishment of ecosystem, and
recharge of groundwater. It is the major floods that are catastrophic in nature, inundating a
significant part of the flat, low-lying lands (especially in Bangladesh which receives the
major brunt of floods), with a seemingly increasing frequency of occurrence, are of great
concern. The dry season water availability has an important influence on irrigated
agriculture, sustenance of ecosystem, navigation and prevention of salt water intrusion in the
coastal areas. A large number of people are dependent on irrigated agriculture for their
living. Again occurrence of arsenic in sub-surface water in the lower reaches of the basin in
India and Bangladesh has also added a new dimension to the problem. The ecology of
Bangladesh, especially in the southwest region has already suffered to a significant extent. In
addition, the system carries up to a billion and a half tons of sediment per year that originate
in the foothills of the Himalayas. The high rate of sedimentation of the major rivers and their
tributaries has been affecting not only the carrying capacity of the rivers but also drastically
reduced their retention capacity.
Management of water resources in the region becomes more challenging because of the huge
population, the anticipated population growth and the prevailing poverty situation. The GBM
basins have a combined population of about six hundred million--far greater than the
population of North America or Europe. More importantly, this huge population is still
growing at a rate of over 2 percent per year, leading to enormous pressure on the land and
water resources throughout the region. It is one of the poorest regions of the world, with
about 250 million people surviving on less than USD 2 per day (Ahmad et al. 2001; Ahmad
et al. 1994). However, the region is well-endowed with good natural resources in terms of
land, water and energy, which regrettably, have not been developed or managed wisely in the
past for a variety of reasons.
The disputes or conflicts with transboundary rivers between India and Bangladesh and Nepal
and India have been there for a long time. The development and management of the huge
basin has been subject to a number of geopolitical constraints in spite of having huge
potential of being a great example of regional cooperation (Brichieri-Colombi and Bradnock,
2003). A widely known conflict surrounds the sharing of the Ganges, which originated in
1975 when India constructed a barrage at Farakka to divert water from the Ganges to the port
city of Kolkata. As noted in numerous articles (see for example, Abbas, 1982; Crow et al.,
1995; Chapman and Thompson, 1995; Crow and Singh, 2000), negotiations over the sharing

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and joint development of the Ganges and Brahmaputra rivers in the past have been long-
drawn–out and unproductive. The water sharing disputes between Nepal and India date back
to early twentieth century, and attempts to resolve the issues started with the Sarda Barrage
Agreement in 1920 followed by several agreements through 1950s. But the story of success
was far from being smooth; the agreements seemed to be „sellout‟ of their resources to many
Nepalese people. However, the signing of the Ganges Water Treaty between India and
Bangladesh in December 1996 and the Mahakhali Treaty between India and Nepal in January
are regarded by many as a creation of a climate of goodwill and mutual confidence, offering a
window of opportunity for water-based collaborative development endeavors in the region.
Although the clauses of the treaties have yet to be exercised to their fullest extent, they are
acclaimed as landmark events. However, while so much could have been done, achievement
in terms of sharing and management of water resources of these rivers and sharing and
exchange of information and data through mutual cooperation has not been encouraging
(Anwar, 2004). The recent plans of river linking and construction of Tipaimukh dam,
without any consensus among riparian countries, have generated considerable concerns in
Bangladesh and also widely in India.
The main objective of the river linking project is to divert large volume of water from the so-
called water surplus areas to the water deficit areas in India. The Ganges and the
Brahmaputra River basins have been identified as marginally surplus and surplus areas
respectively, while most of the western and southern areas have been identified as the water
deficit areas. The transfer of water would therefore primarily occur from the Ganges and
Brahmaputra river basins. Bangladesh has voiced its concern to the Indian side formally.
Unfortunately, the response from India has been discouraging to initiate a fruitful dialogue on
the issue. Nepal being strategically located, with India as its lower riparian neighbor, is also
worried about submersion of vast areas within its territory along the Indo-Nepal borders in
case big dams and reservoirs are built across the border as envisaged by the River Link
Project. These are some of the unresolved issues, which are creating uneasy relations
between the neighbors in South Asia and preventing a wider development potential of the
rich water resources in the GBM Basins. Seemingly there is a general lack of mutual trust
and confidence among the riparian states.
Recognition of the importance of regional cooperation by the international community has
been manifested in the development and codification of internal laws and conventions. As
potentially large source of international tension, water conflict has also been the focus of
numerous international forums, and is increasingly becoming subject to international laws
and agreements. A number of customary principles of international water law have evolved,
a number of which have been codified into conventions (e.g. Helsinki Rules 1966, United

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Nations Convention of Non-navigational Uses of Water 1997). These principles and
conventions essentially restrict unilateral decision on water use and intervention on
international rivers and advocates for and provides guidance on equitable, reasonable and
sustainable arrangement for sharing of waters. They have been invoked in a large number of
interstate and international water sharing cases including joint management of watersheds
and water sharing treaties. While the examination of the Ganges Water Treaty and the
Mahakhali Treaty reveals the consideration of the principles during their developments,
neither India‟s river linking plan nor its plan for the Tipaimukh dam adheres to the principles
of international water law.
It is important to realize that transboundary rivers, typically considered as a source of
conflicts, can be a great catalyst for cooperation as well. International rivers have provided
an incentive for riparian states to discus and agree on modalities for cooperation in a number
of regions including programs for development of the shared resource such as joint
hydropower, irrigation and flood control projects, establishment of joint mechanisms for the
management of shared water courses (Salman and Uprety, 2004), and exchange of data and
information on such water courses. Integrated basin management is in practice in a number
of regions, including the Mekong River Basin Organization, the Nile Basin Initiative, the
Murray Darling Basin. Immense possibilities are there to convert waters of the Ganges,
Brahmaputra, Meghna and other transboundary rivers into wealth. Huge hydro-electric,
irrigation, flood control and water transport potentials remains unused in the basins of the
Ganges, the Brahmaputra and the Meghna. Joint efforts in flood management, storage
reservoirs which could be shared cooperatively by the co-basin countries, cooperative
endeavors in reducing and preventing water pollution in trans-boundary rivers, water
power generation and trade, inland navigation and access to the sea, disaster management
and catchment management are some of the major dimensions of the management and
utilization of the GBM waters in South-Asian development.
It is the best interest of all co-riparian countries to take a comprehensive, consensus-based
approach to the water resources development within the river basins. The opportunity cost of
delay on the part of basin countries, both in terms of exhilarating potential benefits foregone,
and also in terms of the compounding environmental deterioration and the mounting costs of
flood damages are well illustrated in Mehta (1992). Many studies and syntheses of
information have demonstrated that transboundary cooperation in integrated water
management in the GBM system can offer these countries benefits far beyond those that can
be achieved through isolated national efforts (Ahmad et al., 2001; Ahmad et al., 1994;
Ahmad and Ahmed, 2001; Gyawali, 2001).

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1.2 Aim of the study
This report aims at presenting an overview of issues and problems relating to the
transboundary water sharing among the riparian countries in South Asia. It also reviews the
potential areas of regional opportunities and cooperation in detail, and implications of
interventions by basin countries. It also seeks to find some answers regarding resolution of
some long standing disputes among the riparian nations. The report is primarily based on
secondary literature and information, with the exception of a primary analysis conducted for
the analysis of demand and water availability of basin countries presented in Chapter 3. In
this report, „South Asia‟ refers only to the countries that have a share in the Ganges-
Brahmaputra-Meghna river basins in the subcontinent. This report is therefore concerned
with Nepal, India, Bangladesh, Bhutan, and China. The former three countries are covered in
more detail as they appear to be the major role players in the regional water management
intervention processes.
1.3 Structure of the report
The report is organized into eleven chapters. Chapter 2 gives description of the river basins,
and the socio-economic conditions of people therein. It also discusses different water
management issues surrounding the basin countries. The impact of climate change is
discussed as a water management issue separately in Chapter 3. Chapter 4 identifies different
areas where the riparian countries can make sustainable developments. The importance of
multilateralism and basin-wide water management are highlighted here. Water policies of the
basin countries are reviewed, especially in the context of issues relating to transboundary
water sharing and regional cooperation. A synthesis of demand and water availability in
respective countries is made in Chapter 6. Chapter 7 includes a review of the history of
regional cooperation in South Asia, and also a brief review of inter-state cooperation status in
India. India‟s river linking plan is thoroughly reviewed in Chapter 8. The details of the plan
are given as much as possible, and the possible adverse impacts, both from India‟s and
Bangladesh‟s points of view are discussed. Chapter 9 includes a thorough review and
analysis of customary water principles and international water law, followed by a discussion
on the application of those principles in South-Asian context. It also critically examines the
legal context of the river linking plan. Chapter 10 draws experiences from international
conflicts and cooperation from other regions of the world. Some good examples of Treaties
and Basin-wide water management systems are discussed in detail. Chapter 11 presents the
conclusions.

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Chapter 2
GBM Basins – Water, Land, and People
2.1 Introduction
The management policy and techniques not only have to take into consideration the physical
and environmental backgrounds concerning the entire catchment, channel, and floodplain but
also, as rivers are intimately associated with people, the prevalent economic, cultural, social
and geopolitical backgrounds. In line with this, the physical and environmental
characteristics of the three basins are described first, followed by a review of the socio-
economic conditions of the basin countries. Water management issues surrounding the basin
countries are illustrated in detail.
2.2 GBM – three separate basins
It is very important to recognize that although the three major rivers ultimately terminate into
the Bay of Bengal through the Lower-Meghna in Bangladesh, the river basins of the Ganges,
the Brahmaputra and the Meghna are distinctly different from each other, and are three
separate basins. They are physiographically separate because each originates and travels
through separate physiographic units, geographically separate because each has its own and
separate catchment zones, geologically separate because each has developed its valleys and
drainage networks in discrete and dissimilar structures (Khan, 2004). Khan (2004) points out
that the United Nations publication in 1972, the World Meteorological Organization (WMO)
in 1987 and the Irrigation Atlas of India prepared by the Indian Irrigation Commission in
1989 have recognized and shown the Ganges, the Brahmaputra and the Meghna as three
separate basins.
However, several recent studies appear to have incorrectly term the three-basins as one single
basin (e.g. Wolf et al., 1999; Gleick, 2000; UNESCO, 2002). Wolf et al. (1999) and Gleick
(2000) estimate that there are 261 international river basins shared by two or more countries,
covering 45.3% of the land-surface of the earth (excluding Antarctica). The number was
later updated to 263 (see UNESCO, 2002). The number grew from an estimate of 214
transboundary river basins listed in 1978 (UN, 1978), largely as a result of the
„internationalization‟ of national basins through political changes, such as break-up of the
Soviet Union and the Balkan States (the former Soviet Union split into 15 independent states,
the former Republic of Yugoslavia split into five republics, and Czechoslovakia and Ethiopia
both split into two states), as well as access to better mapping sources and technology.
However, as Salman and Uprety (2002) points out, the methodology adopted in the above
delineation has a problem in that it grouped together major rivers that join above an outlet to

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the ocean or to a terminal (closed) lake or inland sea. This resulted in treating the Ganges,
the Brahmaputra and the Meghna as one basin. These are three separate basins, each with
own riparian and one of them is covered by a treaty, whereas the other two are not.
Similarly, the Juba-Shibeli rivers (Ethiopia, Somalia and Kenya) are presented as one basin,
whereas those are two separate basins. As Salman and Uprety (2002) points out, the
methodology also fails to include some major rivers like Mahakhali, which is covered by a
Treaty between India and Nepal, simply because it joins the Ganges basin at some point, but
lists some seasonal streams as international rivers that end in the sands.
2.3 GBM basins characteristics
Of the entire GBM basins, 62 percent lies within India, 18% in Tibet, 8% in Bangladesh, 8%
in Nepal and 4 percent in Bhutan. This report concerns itself mainly with India, Nepal and
Bangladesh and often speaks of them as the „basin countries‟. Bhutan is a country of very
small population, has close ties to India, and has a mountainous geography similar to that of
Nepal. Nepal is exclusively an upper riparian state, since all its rivers arise within its own
borders and pass into India. Bangladesh, located on the expansive Ganges delta, where the
basin empties into the Bay of Bengal, is exclusively a lower riparian. It receives the worst of
flooding during the monsoon and suffers serious water shortages during the rest of the year.
India is middle riparian of some important rivers, and also an upper riparian in the case of
some rivers. The Himalayas within its borders give rise to several major tributaries of the
Ganges. At the same time, its eastern states receive the runoff of the Brahmaputra from the
Tibet, while Uttar Pradesh and Bihar receive from Nepal the runoff of several Gangetic
tributaries.
2.3.1 The Ganges Basin
The river system
The Ganges rises from the Gangotri glacier in the Himalayas at an elevation of about 7010 m
near the Indo-Chinese border. From Hardwater to Allahabad, the river flows generally in a
south-easterly direction and in the lower reaches it flows eastward and enters Bangladesh
near Rajshahi. The length of the main river is about 2550 km (1584 miles). The Ganges
basin practically covers the whole of the northern India between the Himalayas and the
Vindhyas except the state of Punjab and Jammu and Kashmir. During its middle course on
easterly direction, a number of big and small tributaries have joined on the northern side (left
bank) from the Himalayan sub-basin, namely, Ramaganga, Gomati, Ghagra, Gandak and
Kosi, all of which have their origins within the mountain range of the Himalayas in Nepal.
Three major Himalayan tributaries of the Ganges flowing from Nepal to India are the
Karnali, the Gandaki, and the Kosi, which contribute significant proportion of the total annual
flow of the Ganges. On the Southern side (Right bank), the tributaries are Yamuna, which

17
has joined the Ganga at Allahabad, and other major & minor tributaries are, Kehtons, Sone,
Kiul and Punpun, which have origins from peninsular sub-basin. After entering Bangladesh
completely, it flows for another 113 km before joining Brahmaputra near Goalanda.
Downstream of Farakka, there are only two tributaries that join the Ganges- the Mohananda
and the Baral. The combined course of the Ganges and the Brahmaputra takes the name of
Padma, which joins the Meghna at Chandpur. From this confluence, the combined course of
the three rivers continues as the lower Meghna into the Bay of Bengal. The river system of
the Ganges is shown in Figure 2.1.
Figure 2.1 The Ganges basin and its river system
Basin characteristics
The Ganges and its tributaries have formed one of the largest flood plains in the world with
the sediments from the erosion of mountainous areas. The Ganges Basin is formed by a 200
to 300 kilometer-wide plain, bordered by the mountains and highlands on three sides. The
Ganges Basin River system remains the main source of freshwater for half the population of
India and Bangladesh and nearly the entire population of Nepal. The importance of the
Ganges can hardly be exaggerated, particularly in its lower stretch, where it is the only river
from which freshwater supplies are obtained for the distributaries (small rivers that distribute
waters through a flood plain during peak flows).

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The total catchment area of Ganges is about 1,087 thousands sq.km lying in India (860
thousands sq.km), Nepal (147 thousands), China (40 thousands sq. km.) and Bangladesh (46
thousands sq.km). Only 4% of the total catchment area of the Ganges lies in Bangladesh (see
Table 2.1 for details). The catchment area of the Ganges river basin is divided in the ratio of
3:2 between the peninsular sub-basin and the Ganga sub-basin; but the discharge contribution
is just the reverse, i.e., 2:3 (reference???). This has been possible due to the much higher
intensity of rainfall in the Himalayan mountain range and also at the foot of the Himalayas,
compared to that of the peninsular regions. Three major Himalayan tributaries flowing from
Nepal, Karnali, the Gandaki, and the Kosi contribute about 70% of the natural dry season
flow and 40% of the total annual flow of the Ganges.
The cultivable area of the basin is estimated at 65.8 Mha, of which 60.2 Mha is in India.
lying in India and Bangladesh (Adhikari et al., 2000). The population in 1996 was estimated
at 427 millions. The population density is very high, particularly in the lower reaches.
Table 2.1 Catchment areas of the GBM basins (Source: Ahmad et al., 1994)
Country Ganges Basin Brahmaputra Basin Meghna Basin
Basin area
(1000 km2
)
% of total area Basin area
(1000 km2
)
% of total
area
Basin area
(1000 km2
)
% of total
area
China 40 4 293 50 333 19
Nepal 140 13 140 8
Bhutan 45 8 45 3
India 861 79 195 34 1,098 63
Bangladesh 46 4 47 8 129 7
Total 1,087 100 580 100 1,745 100

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Figure 2.2 Schematic of the Ganges river system showing flow contributions of tributaries
Hydrologically, the Himalayan Rivers are, of greater importance as regards water resources
management compared to the peninsular streams. Amongst the Himalayan streams, the
Ghagra with its tributaries contributes maximum run-off (about 94,500 Mm3) and the Gomati
contributes minimum run-off (about 7,400 Mm3). Amongst the peninsular streams, the Sone
contributes maximum run-off (about 32,000 Mm3) and the Kiul contributes the minimum
run-off (about 35,000 Mm3 ). Although the river‟s annual flow regime is subject to local
variations, the predominant pattern is for a low-flow dry season from January to May and a
wet season from July to November, with peak flows usually occurring in August. The waters
of the Ganga carry one of the highest sediment loads anywhere in the world, with a mean
annual total of 1.6 billion tonnes, compared to 0.4 billion tonnes for the Amazon.
2.3.2 The Brahmaputra Basin
The river system
The Brahmaputra River has its origin on the northern slope of the Himalayas in China
(Tibet), where it is called as Tsan-Po. After rising south of the lake Konggyu Tsho in Tibet
(China) very near to the Manasarover lake at an elevation of 5150 meters (16,896 ft), the
river under its Tibetan name of Yarlung Zangbo Jiang flow through southern Tibet (China)
for about 1750 km eastwards and parallel to the main range of the Himalayas. In this reach, it

20
receives the waters of important tributaries Raga Tasangpo. Ngang Chu, Kyi chu, and Grimda
chu. Thereafter flowing southwards, it enters Assam valley where two important tributaries,
the Debang and Luhit join the river, from which location it is known as the Brahmaputra.
The river then rolls down the Assam valley from east to west and afterwards swings round
the spurs of the Garo hills, enters Bangladesh and flows in the north-south direction. In this
reach, the river receives flows from several important northern tributaries including Manas
and Sankosh originating in Bhutan. In Bangladesh, the river flows for about 270 km (168
miles) to join the Ganges near Aricha. The river reach between Noonkhawa (where the river
leaves India and enters Bangladesh) and Aricha is popularly known as Jamuna in Bangladesh.
The river takes the name Padma thereafter. Teesta, Dudhkumar, Dharla, Karotoya and Atrai
are the important tributaries of the Brahmaputra in Bangladesh. The important distributaries
are the old Brahmaputra, Jhenai and Dhaleswari. The total length of the Brahmaputra is
about 2900 km (1801 miles). The river system of the Brahmaputra is shown in Figure 2.3.
Figure 2.3 The Brahmaputra basin and its river system
The Brahmaputra river basin extends to four northeastern states of India viz. Arunachal
Pradesh, Assam, Meghalaya and Nagaland; with an area of 194 x 103 km2
. The river has
more than 100 tributaries, of which 15 in the north and 10 in south are fairly large. The
geomorphology of the Brahmaputra basin presents both great challenges and opportunities.
The river remains largely unregulated, partly due to the technical challenges of developing
major water infrastructure given the scale of the river; its extremely high sediment loads
(amongst the largest on earth); and significant and regular seismic activity in the river‟s upper
reaches adjacent to the Himalayas.

21
The Brahmaputra has a total catchment area of 552,000 sq.km. (213,127 sq. miles) with
270,900 sq.km (104,594 sq. miles) in China, 47,000 sq.km (18,147 sq. miles) in Bhutan,
195,000 sq.km (75,290 sq.miles) in India and 39,100 sq. km (15,097 sq. miles) in Bangladesh
(see Table 2.1). Only 7.08% of the total catchment area of this river lies in Bangladesh. One
of the largest rivers of the world, the Brahmaputra has an average annual flow of 585.6
bcm/yr. The discharge of the river is mostly contributed by the snowmelt in China (Tibet) on
the other side of the Himalayas before it enters Arunachal Pradesh. In Arunachal Pradesh,
Assam and Meghalaya of India and Dinajpur and Mymenshingh districts of Bangladesh
(Northern side) rainfall is quite heavy and this contributes substantial amount of flow in the
river. Before the Brahmaputra reaches Bangladesh, 26.5% of the total flow is contributed by
the areas in China and 73.5% by the areas in India (see Figure 2.4). The basin has a very
steep gradient in the north and eastern sides but extremely gentle gradient in the south, falling
at the rate of 13 cm/km. More than 660 m3
/ km2
silt load is brought by the northern tributaries
and about 100m3
/km2
by the southern tributaries.
The cultivable area of the basin is estimated at 9.3 Mha, mostly in India and Bangladesh
(Adhikari et al., 2000). The population in 1996 was estimated at 82 millions, with more than
half living in Bangladesh. .
River name Annual
discharge
(million m3
)
%
contri-
bution
Dihang 186,240 31.63
Dibang 39,085 6.64
Lohit 46,564 7.90
Burhi Dihing 10,996 1.87
Disang 5,010 0.85
Dikhou 3,511 0.60
Subansiri (S) 57,298 7.92
Dhansiri (S) 6,084 1.03
Jia Barali 28,890 4.9
Dhansiri (N) 2,295 0.39
Kopili-Kalang 8,640 1.47
Manas 32,258 5.48
Sonkosh 16,556 2.81
[Source: Sarma, 2003]
[Source: CEGIS]
Baruria
Ganges
Gorai
LowerMegna
Koratoa
Old Brahmaputra
Upper M
eghna
Teesta
Sankosh
Brahmaputra
32.25 BCM
16.55 BCM
45 BCM
1.18 BCM
311.8 BCM
Dhaleswari
D
ihang
186.24BCM
39BCM
Burhi Dihing
D
ibang
Lohit
Subansiri
Jia Bharali
Manosh
46.56
BCM
57.30BCM11BCM
28.89BCM
Brahamaputra total flow 537 BCM, India
73.49 %, China 26.51 %
Figure 2.4 Schematic of Brahmaputra river system showing flow contributions of tributaries
2.3.3 The Meghna Basin

22
The river system
The Barak, headstream of the Meghna rises in the hills of Manipur in India. After emerging
from the hills, the river flows in a meandering course till it enters Bangladesh. Near the Indo-
Bangladesh border, the Barak bifurcates into two rivers: the Surma and the Kushiyara. The
Surma receives a number of tributaries from the Khasi and Garo hills while the Kushiyara
receives the tributaries from mner of The Surma-Meghna river system flows on the east of
the Brahmaputra river through Bangladesh. The Surma flows through eastern side of
Bangladesh by the side of Sylhet town and flows southwards. The Kushiara flows through
India and then enters Bangladesh. The Surma and Kushiyara join together Markuli after
which the united stream is called the Kalni, which flow in a southerky direction. The flows
of Someswari, the Kangsa, the Baulai and the Mogra discharge into the Kalni near Kuliarchar
through the Ghorautia. Thereafter the river takes takes the name of Meghna and flows in a
south-westerly direction to meet Padma at Chandpur. Between Kuliarchar and Chandpur the
Titas and the Gumti join from the ridght, and the Lakhya and Buriganga from the left. Below
Chandpur, the combined river is known as the lower Meghna, one of the largest rivers in the
world. The total length of the river is about 902 km of which 403 km is in Bangladesh. The
Meghna drains the hills of Assam, Meghalaya and Tripura states in India and the north-
eastern part of Bangladesh. The river system of the Meghna is shown in Figure 2.5.
Figure 2.5 The Meghna basin and its river system

23
In comparison with the Ganges and the Brahmaputra, the Meghna river system is small. The
total catchment area of Barak/Meghna is 85,000 sq.km lying in India (49,000 sq.km) and
Bangladesh (36,000 sq.km). The average annual discharge of the Meghna at Bhairab Bazar
upstream of its confluence is round 150 BCM. The cultivable area of the basin is estimated at
4 Mha, lying in India and Bangladesh (Adhikari et al., 2000). The population in 1996 was
estimated at 40 mullions, the majority of whom are in Bangladesh. .
2.4 People of the basins
Water is the single most important natural resource of the GBM regional countries and it is
widely it is important to recognize that this resource must be developed and managed in a
rational, efficient and equitable way, so that it can act as the engine for socio-economic
development, shaping the future of millions of people living in this region. The GBM basins
(excluding the part of them falling within Tibet) accounts for a large share of the world‟s
population, an estimated total of 535.3 million (1991), of which the share of India is 75.7%
(405.4 million), Bangladesh 20.5 percent (110.0 million), Nepal 3.5 percent (18.5 million),
and Bhutan 0.3 percent (1.5 million) (BUP and others, 1994). The total population of the
region was estimated at 600 million in 1999, which is significantly higher than that of entire
North America, that is, Canada, United States and Mexico combined. Of these 600 million
people, 460 millions are in India, 114 million in Bangladesh and 22 millions in Nepal (whose
almost entire territory is in the Ganges basin).
Table 2.2 Some salient details of the GBM region

24
The density of population is highest in the plains, especially in Bangladesh (740 per sq.km.)
and adjacent Indian states, e.g., West Bengal (686 per sq.km.). Population density is
significantly lower in other Indian states, particularly in the hills of the northeast and the
Himalayan belt, Nepal and Bhutan. Population density varies widely over the area of the
basin from a high of 717 per square kilometer in Bangladesh to a low of 121 per square
kilometer in Nepal. India falls between the two with a density of 238 per square kilometer
(Rogers et al., 1989; University of Texas at Austin, 1993). The average population growth
rate in the region over the past decade was around 2 percent per annum. The region‟s large
and growing population makes the efficient use of the basin‟s water resources particularly
imperative. By the year 2020, the population of the basin may reach one billion (University
of Texas at Austin, 1993). Figure 2.6 shows the population growth trends in the three major
basin countries.

25
0
50
100
150
200
250
Population
(millions)
1995 2005 2015 2025 2035 2045
(a) Bangladesh [Source: WARPO, 2001]
0
500
1,000
1,500
2,000
Population
(millions)
1950 2000 2010 2025 2050
(b) India [Spurce: UNFPA]
0
10
20
30
40
50
60
Population
(millions)
1950 2000 2010 2025 2050
(c) Nepal [Source: UNFPA]
Figure 2.6 Population in three major basin countries
Some important socio-economic parameters of the three major basin countries are presented
in Table 2.3. The region is one of the poorest of the world, with about 250 million people
surviving on less than USD 2 per day (Ahmad et al. 2001; Ahmad et al. 1994). Other social
indicators like literacy, infant and child mortality are lower than the world‟s average. While
access to safe water has increased, sanitation remains woefully inadequate. The per capita
availability of arable land is very low, about one tenth of a hectare (Ahmad et al. 2001;
Ahmad et al. 1994; Ahmad and Ahmed, 2003). The existing urbanization rates are also low,
but likely to rise significantly in India and Bangladesh. There have not been marked
improvements in the standards of living of the people due to, other than growth of population,
lack of employment generation opportunities, and declining environment and resource base.
Nearly half of the total regional population currently lives below the poverty line, and despite
recent advances, the total number of poor people has continued to increase. Adult literacy
rates are low, (28 percent for Nepal, 38 percent for Bangladesh and 52 percent for India).
Health indicators are equally abysmal, and the use of commercial energy continues energy
continues to be low indicating the lower level of economic development of the area. Per
capita GNP for Bangladesh, India, and Nepal is (as of 1998) US$350, US$430 and US$210
respectively; the corresponding global average is US $4,890. The three countries spend a
lower share of public expenditure on education compared to the world average. The global
average is 4.8 percent of GNP, while it is only 2.9, 3.4, and 2.8 percent in Bangladesh, India
and Nepal, respectively.

26
Table 2.3 Important socio-economic parameters of major basin countries
Parameter Bangladesh India Nepal
Population (million) 1998 128 987 24
Annula population growth rate (1995-2000) 1.9 1.8 2.5
Infant mortality rate (per 1,000 liv ebirths) 1997 75 71 83
Under-5 mortality rate (per 1,000 live births) 1997 104 88 117
Maternal mortality rate (per 100,000 live births) 1990-1997 850 437 1,500
Access to safe water (% of population) 1995 84 85 59
Access to sanitation (% of population) 1995 35 29 20
Adult literacy rate (% of people 15 and above) 1997 50 (M)
27 (F)
67 (M)
39 (F)
56 (M)
21 (F)
Female (as % of labor force) 1998 42 32 40
Arable land (hectare per capita) 1994-1996 0.07 0.17 0.13
Population below national poverty line (%) early 1990s 48 37 43
Per capita GNP (US$) 1998 350 430 210
2.5 Cultural and religious importance of water
Water has important implications for most religions of the world. The existence of any living
agent is dependent upon water. This is one of the reasons for which water has been linked
with different cultures and religion, and it is no different in South Asia. For example,
according to Hindu mythology, the Ganges River came down to Earth from the heavens, and
that is why the Ganges is considered a heavenly or sacred resource by millions of Hindus in
India. The river symbolizes purification to millions of Hindus who believe that drinking or
bathing in the waters of the Ganges (Ganga jal) will lead to salvation, a happy and healthy
life. Many Hindus keep water from the Ganga in glass bottles as a sacred relic, or for use in
religious ceremonies. The river becomes the final resting place for thousands of Hindus,
whose cremated ashes or partially burnt corpses are placed in the river for spiritual rebirth.
This religious significance creates an interesting paradox for the health of the river. Because
of the enormous social significance and heavy utilization of Ganga water, people are highly
concerned about river water quality and health. On the other hand, faith in the purifactory
powers of the Ganga lead to a sort of collective disbelief that the water could be polluted or
harmed in any way, and its cleansing powers are often extended to physical as well as
spiritual pollution, assuming that the purifying capacity of the river can overcome any
amount of human waste or toxic substances released into it (Kelly, 2002). In the Indian
tradition, rivers have always been regarded as gods or goddesses. The Brahmaputra, the
Bhagirothy, the Cauvery – almost all the rivers crossing over India have got names of Indian

27
of Hindu gods and goddesses. Plenty of verses and musicals are written in the name of these
popular and significant rivers (Hoque, 2004).
Rivers and water are also closely interlinked with the different religions of Bangladesh, i.e.
Hindu, Muslim, Buddha, Christian (Novak, 1993, reported in Rahman, 2005). Water is
sacred for every religion. Karatoya River is sacred to the Hindus. Every year around mid
April and once every twelve years in December, hundreds of thousands of Hindu pilgrims
gather at the site for a bathing ritual. The bank area of the river Turag in Tongi city hosts
Viswa Ijtema (World Muslim Congregation), a big Muslim religious congregation organized
annually since 1966. It is an annual meeting place of Muslim pilgrims from various countries
of the world for special prayers.
2.6 Major water resources management issues
There are a number of common water resources management issues for all countries in the
GBM Basins. Water demand for irrigation, domestic and industrial uses is increasing with the
increase in population, economic activities and change in life style. Despite all these
indicators of poverty and backwardness, the GBM region is water-rich. The average annual
water flow of the region is 1350 billion m3 (BCM), while the replenishable reserve of
groundwater is 230 BCM. However, there are gross inequalities in the distribution of water
temporally as well as spatially. The countries experience floods and water scarcity in various
degrees. The GBM countries are severely affected by recurrent floods, which cause damage
to life, property, and infrastructure. The general flooding pattern is similar in all the three
countries, characterized by some 80 percent of annual rainfall occurring in four to five
months of monsoon, often concentrated in heavy spells of several days. The GBM rivers
convey an enormous amount of sediment from the mountains to the plains, which often
compound the adverse effects of floods. The unequal temporal distribution of rainfall
creates the problem of low water availability during the dry season and unequal spatial
distribution creates a water stressed conditions in parts of the basin.
Important secondary consequences of flood flow are riverbank, char (river and deltaic
islands), and coastal erosion. These are localised on-going processes, but tend to accelerate
and become more severe during times of floods and cyclones. The Ganges basin is
experiencing extensive erosion due to natural geomorphological conditions, intense rainfall,
frequent seismic activity and inappropriate land use practices (Bangladesh-Nepal Joint Study
Team, 1989). Erosional processes along the rivers render some millions of poor people
landless. Quality of water is deteriorating with indiscriminate use of fertilizers and pesticides
for agriculture, dumping of untreated municipal waste and industrial effluent in water bodies,
lakes and rivers, increasing withdrawals for various uses, and insufficient stream flows to

28
dilute the pollutants during lean flow periods. Further development of groundwater for
irrigation and other uses has been found to be unsustainable, insinuating the need for
developing surface water resources and conjunctive use of surface water and groundwater for
agriculture and other uses. Arsenic contamination of groundwater is a major concern for
almost the entire Bangladesh, and West Bengal of India.
2.6.1 Water management issues in Nepal
Floods.
Major floods experienced in hill valleys are due to sudden cloudbursts which are localized in
nature, but may be heavy for several days. In the higher mountains, major floods are
induced by glaciers, i.e., Glacier Lake Outburst Floods (GLOF) (Bangladesh-Nepal Joint
Study Team, 1989; Ahmad et al., 2001). Rockslides and landslides which are common in
Nepal also aggravate flooding problems by reducing river capacity or even temporarily
damming the rivers. As 80% of the annula surface run-offs occurs during the monsoon
period, the rivers in Nepal (mainly Sapta-Kosi, Gandaki, Karnali and Mahakhali), when
debouching into the plains, cause immense damage in the terai are of Nepal and adjacent area
of India. In Nepal, the runoff generated by heavy precipitation can not quickly drain out,
often because of high stage of the outfall river. The peak monsoon flows are increasing due
to the loss of vegetative cover in the catchment area The Nepalese terai region is prone to
flash floods, which also produce spillover effects in northern India
Erosion and sedimentation
The Ganges river system carries and delivers a large quantity of sediment each year into the
Bay of Bengal. The entire area of Nepal lies within the Ganges basin, and the gravity of the
problem of erosion is very critical. Catastrophic consequences, particularly in terms of loss of
top soil from potential agricultural land occurred due to the combined action of natural
geological process and the accelerated erosion due to human activities. In much of the
Himalaya, the erosion is dominated by landslides, rock failures and river channel erosion, and
most of these are of natural origin.
Water quality
In Nepal, water quality has deteriorated mainly due to industrial pollution. The volume of
effluents generated by most industries is not large, but the concentration of pollutants is
remarkably high.
Water availability and use
Increasing population and industrial expansion, together with a growing demand from
urbanization and irrigation sector is to continue to result in increased competition for water.

29
In Nepal, agriculture is the single largest sector with reference to income and employment
though its share in GNP has declined from 70 percent in 1974-75 to around 50 percent or less
(Rangachari and Verghese, 2001). The agrarian economy employs approximately 81% of the
work force. In terms of volume, irrigation is the greatest water user with over 95% of the
total water consumed being used in this sector. Out of the total land area of Nepal, the
cultivated area is about 2.6 Mha (inclusive of 0.4 Mha of forest), of which only 40% is
irrigated. There is a total net irrigable area of about 1.76 Mha excluding the forestland. Of
this total, 1.36 Mha are located in the Terai and 0.41 Mha are situated in the hills and the
mountains (Malla et al., 2001). Three distinct ecological zones run parallel across the
country, namely, the southern terai plains (23%), the mid-hills (42%) and the northern
mountains.
Statistical figures might indicate that there is plenty of water in Nepal, but the question is
how much of the water is actually available for irrigation at the time of requirement at a
reasonable cost. Most of the irrigation projects constructed by the government divert water
from medium size rivers originating from the middle hills. These rivers, though perennial,
have wide seasonal functions in discharge. The unreliable river flows coupled with the
inefficient management appear to be the factors contributing to poor performance of the
irrigation systems. Tapping the large Himalayan rivers (Kosi, Gandaki, Karnali, Mahakali)
for irrigation and/or hydropower generation, though promising, needs bilateral and
multilateral cooperation as well as considerable resources.
2.6.2 Water management issues in India
Floods
Floods have become an annual feature in the GBM plains of India. Floods are caused by a
number of factors, singly or in combination, such as excessive precipitation, inadequate river
channel capacity, etc. Although the country receives about 1150 mm (equivalent to 4,000
km3
) of water as precipitation annually (NCIWRDP, 1999), the precipitation is characterized
by acute variations in both space and time. About 80% of precipitation occurs in the four
monsoon months from June to September (Figure 2.7), and a large part of the total
precipitation on the country is received in the Himalayan catchments of the Ganga and
Brahmaputra rivers (which the northeastern quarter of the country) in comparison with the
northwestern, western and southern parts. (Figure 2.8). Flooding conditions also arise from
drainage congestion because of obstruction to free passage of flow by railway and/or road
crossings (Adhikari et al., 2000). Out of 40 million hectare of the flood prone area in the
country, on an average, floods affect an area of around 7.5 million hectare per year (MOWR,
2002). Of the total estimated flood prone area in India, 68% lies in the GBM states, mostly in
Assam, West Bengal, Bihar, and Uttar Pradesh (see locations of states in Figure 2.9). The

30
Ganges in northern India, which receives water from its northern tributaries originating in the
Himalayas, has a high flood damage potential, especially in Uttar Pradesh and Bihar.
Likewise, the Brahmaputra and the Barak (headwaters of the Meghna) drains regions of very
high rainfall, and produce floods from overbank spilling and drainage congestion in
northeastern India. Temporal Variation of RainfallTemporal Variation of Rainfall
0
100
200
300
400
500
600
700
800
900
1000
Winter
Monsoon
(Jan-Feb)
Pre
Monsoon
(Mar-
May
Monsoon
(Jun-Sep)
Post
Monsoon
(Oct-Dec)
Rainfallinmm
All India
Figure 2.7 Temporal distribution of rainfall in India

31
Figure 2.8 Spatial distribution of rainfall in India

32
Figure 2.9 Map of India showing different states
The unequal spatial distribution of rainfall means that the flows in many of the rivers in
northwestern, western and southern parts are considerably less than the Himalayan parts of
the country. An illustration of water availability is given in Figure 2.10. Droughts affect vast
areas of the country, transcending state boundaries. One-sixth area of the country is drought-
prone (MOWR, 2002). India is the second most populated country in the world having a
population exceeding 1 billion. According to current estimates, the population of India will
increase to 1.6 billion by 2050. This will create great pressure on the water resources.
According to a World Bank (1999) estimate, the overall annual demand will increase from
552 BCM to 1050 BCM by 2025. In another study, Kumar (2003) estimates the future
annual demand in 2025 at 1093 BCM. The present per capita water availability is around

33
2000 cubic meters per year. Water availability per capita will drop to 1,500 cubic meters by
the year 2025, well below the level at which water stress is considered to occur (World Bank
1999). Of the present water usage, 92% is devoted to agriculture, with roughly 3% used in
industry and only 5% for domestic purposes like drinking water and sanitation (WRI 2000).
Demand from the industrial and domestic sectors is expected to increase with the growing
population, urbanization and industrialization.
73
525
629
48
12 28
67
111
70
21 6 11 4
46
15
87
114
23 16 15
0
100
200
300
400
500
600
700
Indus
Ganga
Brahmaputra
Barak
Subernarekha
Brahmani-Baitarni
Mahanadi
Godavari
Krishna
Cauvery
Pennar
Mahi
Sabarmati
Narmada
Tapi
TapitoTadri
Tadrito
Kanyakumari
MahanaditoPennar
Pennarto
Kanyakumari
Kachchh/Saurashtra
Cubickm/year
Figure 2.10 Surface runoffs in some Indian rivers [Source: Rao, 2003]
Water quality
The major source of pollution in India is the use of rivers as sewers for industrial and
domestics wastes (Adhikari, 2000). About 50 million cubic meters of untreated sewage are
discharged into them each year (APCSS 1999 as reported in Hossain, 2004). As Hossain
(2004) reports from World Bank (1999), between 0.5 to 1.5 million children under the age of
five die yearly from diarrhoea in India, and in Maharashtra State alone, 0.7 million people
suffer from water-related diseases of which 1,000 die annually (World Bank 1999). Pollution
is usually concentrated near points of waste discharges. Increasing use of agro-chemical has
contributed significantly to the pollution of both surface and groundwater resources.
Improper land management practices have also led to severe soil erosion and water quality
degradation in the form of an increase in sediment load and total suspended solids (TSS)
(MOWR 2000). Besides, water quality has been deteriorated by increasing use of agro-
chemicals and sediment loads from soil erosion because of improper land management
practices (MOWR 2000). The Ganges water usually has a considerable capacity of
recuperating quality; yet organic pollution load in terms of Biochemical Oxygen Demand

34
(BOD) is significantly high at many places, most critical stretch being from Kannauj to
Trighat (Adhikari, 2000). Arsenic contamination of groundwater in many parts of the
northern states, particularly West Bengal, is a great concern for drinking water fresh water
supply. In coastal areas, saltwater intrusion from excessive groundwater pumping has also
contaminated local aquifers, leaving them unusable for irrigation and human consumption.
2.6.3 Water management issues in Bangladesh
Being a lower riparian country surrounded by hills on its three sides, flows in Bangladesh is
principally controlled by how much flow is generated in the upstream catchments of the
Ganges-Brahmaputra-Meghna (GBM) basins. All major rivers flowing through Bangladesh
have their origins outside its borders, and, therefore, any interventions in the upper riparian
regions have a significant impact on Bangladesh. Hence, the country is naturally vulnerable
to the water quality and quantity that flows into it from upstream. Hence, the flow hydraulics
is dominated by the three major rivers – the Ganges, the Brahmaputra, and the Meghna, the
river systems carrying enough water from outside the country each year to inundate the
catchment inside the country with 6 meters of water (Chowdhury et al., 1997). The total
annual runoff of Bangladesh is 1230 billion cubic meters (bcm), of which 85 percent
occurring during monsoon period between June and October (Ahmad et al. 2001), and during
this monsoon season, Bangladesh is affected by flood almost every year. Spatial variation in
rainfall pattern (Figure 2.11), however, renders some areas suffering from droughts. For the
remaining period of the year, neither there is significant flow from upstream nor there is
much rainfall within Bangladesh (see Figure 2.12), and the country becomes water stressed.
Figure 2.13 shows the spatial distribution of average values of annual maximum, annual
average and annual minimum discharges. This illustrates that unlike other deltas, the
seasonal variation in flow is highly skewed with abundant water during monsoon while very
small flow during dry season. The country, therefore, faces two major hazards: floods during
the wet season and scarcity of water during the dry season.

35
Rajshahi
0
10
20
30
J F M A M J J A S O N D
Sylhet
0
10
20
30
F M A M J J A S O N D
Dhaka
0
10
20
30
Comilla
0
10
20
30
Khulna
0
10
20
30
Barisal
0
10
20
30
Chittagong
0
10
20
30
Figure 2.11 Average monthy rainfall distribution (in cm) (BMD data: 1982-2001)
Figure 2.12 Isohyetal pattern of average annual rainfall

36
Figure 2.13 Spatial distribution of average annual maximum, average annual and average
annual minimum discharge in major and medium rivers (Source: Chowdhury et al., 1997)
Floods
Being the lowest riparian, Bangladesh bears the brunt of flooding in the GBM basins. The
extensive floodplain topography (80% of total land area) is a main reason for inundating large
areas. Flood in Bangladesh is an annual phenomenon; about 20% of its area is inundated by
overflowing rivers during monsoon in a normal flood year, about 35% in a moderate flood
year, and more than 60% in a major flood year (Salehin et al., 2007). The normal floods are
considered a blessing for Bangladesh-providing vital moisture and fertility to the soil through
the alluvial silt deposition. It is the abnormal floods that are considered disastrous, i.e., the

37
high-magnitude events that inundate large areas, and cause widespread damage to crops and
properties. The flood prone areas of the country are shown in Figure 5.1.
Figure 2.14 Flood prone areas in Bangladesh
The principal sources of river floods are the major river systems, the Brahmaputra, the
Ganges, and the Meghna, in the monsoon months. Local rainfall floods often accompany
river floods, which result from runoff of high intensity and long duration rainfalls that can not

38
be drained because of high outfall water levels. The northern and north-eastern trans-
boundary hill streams are susceptible to flash floods from the adjacent hills in India in the
pre-monsoon months of April and May. The areas adjacent to estuaries and tidal rivers in the
south-west and south-central parts of the country experience tidal floods twice a day due to
astronomical tide from the Bay of Bengal. During spring tide, which occurs fortnightly, large
area is flooded by tidal water. Tide is experienced upto 225 km inland in the wet season and
325 km inland during the dry season. Approximately 12,000 sq.km. of coastal land is prone
to occasional cyclonic storm-surge floods due to tropical cyclones in the Bay of Bengal
during April to June and September to November. River and rainfall flood are frequently
aggravated by the backwater effect from the sea and the timing of peak flows in the major
rivers. The spring and monsoon wind setup in the Bay of Bengal cause strong backwater
effect in the Lower Meghna river, which is the single oulet of the Ganges-Brahmaputra-
Meghna river system. As a result, drainage is slowed down causing increase in the duration
of flood. Synchronization of peak flows in the Brahmaputra and the Ganges is a major
determinant of the extent of flooding in the country. When the peaks of the two rivers
coincide, which is not a rare event, severe flooding occurs as it was the case in 1988, 1998
and 2004 (Salehin et al., 2007).
The Brahmaputra has the largest flood flow followed by the Ganges and the Meghna, with a
flow ratio of 4.4:2.5:1. The combined discharge of the three main rivers is among the highest
in the world. Peak discharges are of the order of 100000 m³/s in the Brahmaputra, 75000 m³/s
in the Ganges, 20000 m³/s in the upper Meghna and 160000 m³/s in the lower Meghna. The
major river systems discharge about 1,42,000 m3/s into the Bay of Bengal at peak periods
(Rahman et al., 1990).
Sedimentation
The GBM rivers convey an enormous amount of sediment load from the mountains to the
plains, which compound the adverse effects of floods. The Kosi and some tributaries of the
Brahmaputra are particularly notable in this regard. Bangladesh is the outlet of all the major
rivers and receives, on average, an annual sediment load varying between 0.5 billion and 1.8
billion tons.
The current population of Bangladesh is 140 million and it is expected to be 181 million by
2025. More that 36 percent of the population is still living below the poverty line. Achieving
food security for this huge population puts tremendous challenge to Bangladesh‟s water
resources. This will create an additional food grain demand of 9.5 million tons in 2025

39
compared to the demand in 2000. To meet this demand, it will be necessary to bring most
irrigable land under irrigation coverage.
Drought is a common hazard for the rainfed cultivation in Bangladesh. Between 1949 and
1991, droughts occurred in Bangladesh 24 times, 11 of them being very severe (WARPO,
2005). Bangladesh experience long spells of dry weather and moderate to severe droughts
are spread over a region of 5.46 million ha in the districts of Rajshahi, Natore, Chapai
Nawabganj, Rangpur, Dinajpur, Bogra, Kushtia, Jessore and Dhaka.
Dry season water availability in the southwest region of the country has been a major
problem for long. Water availability in that region has been severely affected due to the
withdrawal of water of the Ganges at Farakka by India. Salinity intrusion in the southwest
has increased due to low fresh water flow through the Ganges distributary Gorai during dry
season. This has resulted in major adverse impacts on the environment and socio-economic
condition in the area Salinity now reaches as far as Khulna (see Figure 2.15), creating
problems to normal agricultural practices and affecting the supply of clean water for
industrial use. River water salinity has also important implications for the natural
environment, such as functioning of the Sundarban ecosystem, sedimentation rates in tidal
rivers, and human health.

40
Figure 2.15 Salinity intrusions in the southwest region of Bangladesh
Ecosystem and biodiversity
The Sundarbans, the largest mangrove forest in the world, can only be conserved and
protected through augmenting freshwater flows into the channels of the southwest. The
natural ecosystem of this forest is threatened by freshwater flow reduction from the north and
migration of the salinity front from the south. Dry season surface water flow augmentation
will be essential to combat this degradation. Flows will also be required to restore and
maintain the shrinking wetlands throughout the country, and to improve water quality
through dilution of suspended solids and industrial and agro-chemical pollutants in high
density zones. The 1991 NWP had allocated 40 percent of the total national water
requirements to salinity control, together with fisheries and navigation sector.
Erosion
Mott MacDonald et al. (1993) reported that every year almost one million people were
affected by eroding banks along 75 rivers including the major ones in about 130 different

41
locations, and at least 7 million people were displaced by riverbank erosion between 1970
and 1990. As reported in WARPO (2005), a four year study concluded in 1991 found that out
of the 462 administrative units in the country, 100 were subject to some form of riverbank
erosion, of which 35 were serious, and affected about 1 million people on a yearly basis.
River erosion has major social, economic and environmental consequences. The National
Water Management Plan (NWMP) estimates that by the year 2025 around 3,575 km2
of area
in the erodable river valleys of Brahmaputra, Ganges, Padma, Lower Meghna and estuary
will be lost due to erosion. Each year more than 10,000 people are displaced on an average.
The towns of Sirajganj and Chandpur are under constant threat from the Jamuna and the
Lower Meghna, respectively. Counter-balancing loss of land through erosion is the
deposition of silt and the creation of new lands for settlement. However, erosion processes
are highly unpredictable, and not compensated by accretion (except Meghna Estuary). The
Meghna estuary is a highly dynamic place of erosion and accretion.
Water quality
Industrialization is the main source of water pollution in Bangladesh. The major industries
are located in urban areas along major rivers. Surface water sources in aand around major
urban centers are about 10 times more polluted than average surface water quality of the
major rivers (Adhikari et al., 2000). The river Buriganga on which stands the capital city is a
typical example of pollution due urbanization. The increased use of agrochemicals and the
discharge of untreated domestic sewage and industrial effluents into rivers have aggravated
the problem. In Bangladesh, the magnitude of water quality deterioration from the above
mentioned causes is further compounded by salinity intrusion in the southwestern region, as
mentioned above. The reduced flow of the Ganges in the dry season, coupled with the silting
of distributary mouths, has exacerbated the process of northward movement of the salinity
front, thereby threatening the environmental health of the region. Increase in population and
economic activities have imposed great pressure on ecologically sensitive areas from
encroachment and unsustainable use. This trend is likely to continue in the absence of an
integrated water and land-use management plan. An additional problem is the detection of
high concentrations of arsenic in groundwater in 59 of the 64 districts of Bangladesh and in
some adjoining districts of west Bengal, upsetting the drinking water supply concept,
extracting from groundwater.
2.6.4 Water management issues of Bhutan
The per capita availability of water per annum at 75000 m3
is the highest in the region.
However, the abundance of water at the national level gives a false sense of security. The
uneven distribution of precipitation in time and space has led to seasonal and local

42
imbalances. The mountainous topography has given the country a high potential for
hydropower development. However, the country is confronted with localized and seasonal
water shortages for drinking and agricultural purposes. Today only 78% of the population has
access to safe drinking water and only about 12.5% of the arable land is irrigated. The
fluctuation between lean season and monsoon season flows is on the rise leading to sub-
optimal utilization of generating capacity of hydropower plants. The increasing sediment load
in rivers is decreasing the expected output and economic life of the hydro power plants.
These phenomena are to a certain degree caused by the uneven distributon of precipitation
over the mountainous terrain. Floods and landslides are two major threats that emanate from
such a setting.
The pressure on the water resources is mounting due to competing demands from different
users. In the past, water was mainly used for domestic and agricultural purposes. The
domestic water demand is increasing due to changing lifestyles caused by socio-economic
development. The water use for agriculture will increase due to its intensification to keep
pace with food demand of a growing population. New demands are emerging from other
subsectors such as hydropower and other industries. Urbanisation has become a key issue that
has serious impact on both water demand and quality.
Due to the fast pace of socio-economic development, there is tremendous pressure on the
watershed. The increasing demand on timber, firewood and non timber forest products, is
starting to have negative impact on the watershed. Forestland encroachment and forest fires
have become major challenges for watershed conservation.
At high growth rate of 2.5% per annum, the populations will more than double in the next
thirty years. This growth poses a serious challenge in the sustainable management of the
natural resource base, given the low carrying capacity of the fragile mountainous ecosystem.
Glacial lake outburst floods (GLOF) have increasingly become a threat for Bhutan due to
global warming brought about by climate change. This will have serious impact on life,
properties and future infrastructures development. The natural flow regulating capacity of the
glaciers will decrease.

43
Chapter 3
Climate Change Threat to Regional Water Resources Systems
3.1 Bangladesh
Bangladesh is a South Asian developing country. The country is located in the Bengal basin,
formed by the sediments washed down from the highlands of Himalayas. The basin is
basically a low lying flat delta. The country is criss-crossed by a network of GBM rivers
consisting of the Ganges, the Brahmaputra and the Meghna and their tributaries and
distributaries. About 80% of the country is floodplain of these rivers with very low mean
elevation above the sea level. Differences in the elevation between adjoining ridge tops and
depression centers range from less than 1 meter on tidal floodplains, 1 to 3 meters on the
main river and estuarine floodplains, and upto 5 to 6 meters in the Sylhet basin in the north-
east. Only in the extreme north-west, land elevations exceed 30 meters above the mean sea
level.
The country has a humid, warm, tropical climate with hardly any significant spatial
variability. It is influenced primarily by summer and winter winds and partly by pre-monsoon
and post-monsoon circulation. The south-west monsoon originates over the Indian Ocean and
carries warm, moist, and unstable air. The seasonal variation can be characterized as: (1) A
hot summer with a maximum of 40o
C in the west for 5 to 10 days. Very high rate of
evaporation, and erratic but occasional heavy rainfall from March to June. (2) A hot and
humid monsoon with heavy rainfall from June to October, with about two-third of annual
rainfall occurring this time (3) A relatively cooler and drier winter from November to March
with maximum temperature ranging from 15-20o
C and the minimum occasionally falling
below 5o
C in the north.
There exists a marked spatial distribution of mean annual rainfall throughout the country,
ranging from 1200 mm in the extreme west to 5,800 mm in the east and north east. Temporal
variability of rainfall is also very significant. Over 85% of annual rainfall occurs within May
and October, while winter experiences hardly any rainfall. As a result, evapo-transpiration of
pre-monsoon and post-monsoon is much higher than monsoon. During evapo-transpiration,
top soil loose much moisture contents leading to a high moisture stress.
The agricultural production systems involving crops, forestry, fisheries, and livestocks as
well as the settlement patterns of the country are shaped by the availability and spatial and
seasonal distribution of the country‟s water resources. Differences in depth and duration of

44
seasonal flooding on different soil and land types strongly influences the kind of crops
grown, cropping pattern and cropping rotation.
Bangladesh makes minimal contribution to the global emission of Green House Gases. The
sectoral activities that contribute to the global emission of the Green House Gases includes
energy, agriculture, forestry, livestocks, transportation and households. According to the
World Development Indicators, total emission of CO2 is less than 0.2 ton in Bangladesh,
compared to 1.6 tons in the developing countries and 4.0 tons in the world as a whole. The
rich countries of the world historically have emitted most of the anthropogenic greenhouse
gases since the start of Industrial revolution in the later half of 1700s. The significant
emissions per capita still are being produced by those countries.
The first detailed climate scenario for south and south-east Asia was developed by the climate
Impact Group, as part of the Asian Development Bank‟s 1994 regional study on global
environmental issues. Temperature scenarios for tropical Asia reported by the Climate Impact
Group suggest that temperature would increase throughout most of the region, although the
amount of warming is projected to be less than the global average. There may be differences
within the region, depending on the proximity to the sea. Warming is projected to be least in
islands and coastal waters throughout South Asia and greatest in inland continental areas,
except from June to August, where reduced warming could occur. Over the past 100 years,
mean surface temperatures have increased by 0.3-0.8o
C across the region.
The GCM model predicts that there would be a seasonal variation in changed temperature.
The results reveal that the average increase in temperature would be 0.7o
C in monsoon and
1.3o
C in winter in the year 2030. The corresponding values in the year 2050 are 1.1o
C and
1.8o
C. Therefore, changes in winter temperature would be higher compared to the changes in
monsoon.
For the precipitation, the GCM predicted that the winter precipitation would change only at a
negligible rate in the year 2030. In the year 2050, there will not be any appreciable rainfall in
the winter. On the other hand, monsoon precipitation will increase by 11% in the year 2030
and 28% in the year 2050. The base year was selected as the year 1990.
Excessive rainfall in the monsoon would cause flooding, while there will be little or no
rainfall in the winter. As the rise in temperature would be much higher with a reduction in
already low precipitation in winter, there will be a drastic change in evapo-transpiration in
winter. Relatively smaller effect of evapo-transpiration will be observed in the pre-monsoon
months following a drier winter. The effect of increased evapo-transpiration will be felt in the

45
western part of the country, that often face increased moisture stress due to increased evapo-
transpiration. Higher precipitation in the monsoon months would increase surface runoff in
the rivers, which will increase both flood vulnerability and drainage congestion. Not only the
areas subject to normal flooding would be under water, but also other marginal lands would
be inundated in the changed climate. The overall extent of flood will be increased. On the
other hand, possibilities of moisture stress would lead to frequent draught.
For an active and morphologically dynamic delta like Bangladesh, it is difficult to develop a
specific scenario for net change in sea level. Coastal lands are receiving sediments due to
continued tidal influence, where there are lands which are subsiding. Considering a
combination of relative subsidence and rise in sea level, will give an indication of net change
in sea level. The interesting aspect of net sea level rise is that higher ocean stage along the
river mouth will tend to generate a strong backwater effect, leading to a deceleration of
draining water from the rivers. Such a possibility would have a compounding effect on flood
vulnerability. Since the confluences of the GBM system is within 50-70 km from the Bay of
Bengal, it is likely that the presence of a strong backwater effect will impede recession of
flood waters, thereby increasing duration of floods.
There are over 230 rivers in Bangladesh. However, the surface water system of the country is
dominated mainly by the three major river systems, Ganges-Brahmaputra-Meghna (GBM).
These river system cover about 7% of the surface of the country and discharge about 142
thousand cubic meter per second into the Bay of Bengal at peak periods. From this river
system, about 1.18 million cubic meters of water flows annually to the sea, of which 1.07
million cubic meters or 91% enters Bangladesh from India. Increased precipitation due to the
change in climate is expected to lead an increase in surface runoffs with severe consequences
for flooding in the country.
In the Himalayas, the storage of precipitation in the form of snow and ice (in glaciers) over a
long period provides a large water reservoir that regulates annual water distribution. The
majority of rivers flowing through Bangladesh originating in Himalayas have their upper
catchments in snow-covered areas, flow through deep mountains, and drains into the Bay of
Bengal passing through Bangladesh. If climate change does alter the rainfall pattern in the
Himalayas, the impacts could be felt in the downstream countries like Bangladesh. By and
large, dry season flow in the major Himalayan rivers in a given year results from the
monsoon rainfall of the previous year. Catchments in Nepal supply about 70% of the dry
season flow of the Ganges River, and tributaries of the Brahmaputra River originating in
Bhutan supply about 15% of the total annual flow of the river. If climate change disrupts

46
these resources and alters mountain hydrological regimes, the effects will be felt in countries
that depend on this water resource.
Depending on the inundation characteristics (depth), there are five land categories (F0, F1,
F2, F3 & F4). Land type F0 (high land) is not flooded, whereas, land type F4 (very low land)
is flooded for more than nine months of the year with a maximum flood depth of more than
1.8 meters. In total, flood affect about 6 million hectors of cultivable land across the country.
Of this, about 3.3 million hectors are subjected to flood depth of 30 to 90 centimeters. An
area of about 0.076 million hectors has a flood depth of more than 1.8 meters, which remains
under water for more than nine months in a year.
If climate change induced flooding causes some parts of both F0 and F1 lands to become F2
or F3 lands, then there will be a significant effect in agriculture. Under a moderate climate
change scenario 8% (344, 200 ha) of F0 and 56% (1.77 million ha) of F1 land would become
extremely vulnerable to flooding. Under a severe climate change scenario, 0.67 million ha of
F0 and 1.76 million ha of F1 lands will become F2 land. Moreover, an additional 0.6 million
ha moderately inundated lands will become deeply flooded lands. In extreme cases of poor
drainage during high intensity floods, as it occurred in 1998, recession of water from medium
low to medium high lands gets slowed down.
Documentation of floods in terms flood depth, area affected, damage to crops, damage to
infrastructures, number of people affected, and overall monetary damage started in 1953.
Other major recorded floods prior to 1953 took place in 1787, 1917, and 1943. Based on the
historic records, it is obvious that the frequency, magnitude, and duration of floods have
increased substantially during the last few decades. For example, all major floods covering
more than 30% of the country occurred after 1974. Five floods of such great magnitude
(1974, 1987, 1988, 1998 and 2004) took place during the last 30 years, averaging one in
every 6 years. The total area covered by major floods has been steadily increasing since 1974.
The land area affected by major floods has increased from 35% in 1974 to 68% in 1998.
About 26% of the country is subjected to annual flooding and an additional 42% is at risk of
floods with varied intensity. A 10% increase in monsoon precipitation could increase runoff
by 18% to 22%, resulting in a sevenfold increase in the probability of an extremely wet year
(Qureshi and Hobbie, 1994). Increase of monsoon precipitation by 11% and 20% will cause
increase of surface runoff by 20% and 45% respectively (Ahmed and Alam, 1998). Alam et
al. (1998) reported that, by the year 2030, an additional 14.3% of the country will become
extremely vulnerable to floods, while the already flood vulnerable areas will face higher
levels of flooding. It is also reported that, even if the banks of the major rivers are embanked,

47
more non-flooded areas will undergo flooding by the year 2075. Mirza and Dixit (1997)
estimated that a 20
C warming combined with a 10% increase in precipitation would increase
runoff in the Ganges-Brahmaputra-Meghna rivers by 19%, 13% and 11% respectively.
Increased depth of flooding will be pronounced in the lowlands and depressions in the
Faridpur, southwest Dhaka, Rajshahi, Pabna, Comilla, Sylhet and Mymensingh districts.
An extensive water sector modeling coupled with GIS was performed to study the level of
inundation under different climate scenarios. It was found that between 8% and 17% of the
existing upland areas, along with from 56% to 62% of the existing slightly flooded areas,
would become extremely vulnerable to flood (Alam et al., 1998). It was shown that the lower
Ganges floodplain would become more vulnerable than the rest of the country.
Drainage congestion will be major impact of climate change. The combined effect of higher
sea water levels, subsidence, siltation of estuary branches, higher river bed levels and reduced
sedimentation of flood protected areas will gradually increase water logging problems, and
impede drainage. This effect will be particularly strong in the coastal zone, but will also be
felt in riverine flood plains further upstream. The problem will be aggravated by the
continuous development of infrastructure, reducing further the natural drainage capacity. One
of the key effects of the drainage congestion is that it will increase the period of inundation,
and will expand wetland areas.
3.2 India
In India, studies show that there is an increasing trend of surface temperature, no significant
trend of rainfall on all India basis, but decreasing or increasing trend of rainfall at some
locations.
Water resources in India will come under increasing pressure due to changing climate. More
than 45% of the average annual rainfall in India is wasted by natural runoff to the sea,
according to calculation of Indian scientists. Rainwater harvesting schemes are implemented
in India to minimize this runoff loss based on present rainfall scenario over India to increase
groundwater level. However for the success of those schemes, India should focus on how the
possible climate change will affect the intensity, spatial and temporal variability of the
rainfall, evaporation rates and temperature in different agro-climatic regions and river basins
of India.
Long period average annual rainfall over India is about 117 cm. However, this rainfall is
highly variable both in time and space. Almost 75% of the long term average annual rainfall
occurs in four months, June to September. The heaviest rain of the order of 200-400 cm or

48
more occur over the northeast India and along the west coast. Largely, the annual average
rainfall over the northern Indo-Gangetic plains running parallel to the foothills of the
Himalayas varies from about 150 cm in the east to 50 cm in the west. Over central parts of
India and northern half of peninsular India, it varies from 150 cm in the eastern half to about
50 cm on the western side. In the southern half of the Indian peninsula, average annual
rainfall varies from 100 to 75 cm from east to west. Some regions in the extreme western
part, such as western Rajasthan, receive average rainfall of the order of about 15 cm or less.
There are considerable intra-seasonal and inter-seasonal variations as well.
The year to year variability in monsoon rainfall leads to extreme hydrological events
resulting in agricultural output, affecting population and national economy. Variation in
seasonal monsoon rainfall can be considered a measure to examine climate variability or
change over the Indian monsoon domain in the context of global warming.
The inter-annual variability of the monsoon is expected to increase in the future due to
possible climate change, making the monsoon less reliable as an assured source of water.
Therefore, efforts are needed for more efficient groundwater recharge and harvesting of
rainwater through identification, adoption and adaptation of technological options. According
to Indian perception, harnessing of excess monsoon runoff to create additional groundwater
storage will not only increase the availability of water to meet the growing demand, but also
help in controlling damages from floods.
Also, according to Indian perception, the sub-surface reservoir can store substantial quantity
of water, and are attractive and technically feasible alternatives for storing surplus monsoon
runoff. The sub-surface reservoir, located in suitable hydrological situations, is an
environmental friendly and economically viable proposition. The sub-surface storage have
advantages of being free from adverse effects like inundation of large areas, loss of cultivable
land, displacement of local population and substantial evaporation losses. The structure
required for recharging groundwater reservoirs are of small dimensions and cost effective
such as check dams, percolation tanks, surface spreading basins, pits, sub-surface dykes etc.
and these can be constructed using local knowledge. Much of the future demand needs to be
met from the groundwater resources. The water potential of the Ganga valley (both surface
and groundwater) can irrigate an additional 200 mha of land, which can produce another 80
mt of rice, sustaining another 350-400 million people.
Reports on projected climate change over India shows a changing pattern of rainfall and an
increase in temperature. The spatial and temporal change of rainfall distribution prediction is
not uniform. It is widely known that implication of precipitation primarily depends on its

49
spatial and temporal distribution pattern. Uniform precipitation over a larger area is more
useful than its occurrence over a smaller region. Also, precipitation occurring over a larger
time period would be more effectively utilized rather than when it occurs within a short time
span. Therefore, projected changes in precipitation pattern are not giving a favourable picture
for the sub-continent. Decrease in winter precipitation would reduce the total seasonal
precipitation, implying greater water stress during the lean monsoon period. Intense rain
occurring over fewer days besides causing increased frequency of floods during the monsoon
season, will also mean that much of the monsoon rain will be lost as direct runoff resulting in
reduced groundwater recharging potential.
The enhanced surface warming over the Indian subcontinent by the end of the next century
would result in an increase in pre-monsoonal monsoonal rainfall and no substantial change in
winter rainfall over the central plains. This would result in an increase in the monsoonal and
annual runoff in the central plains, with no substantial change in winter runoff and increase in
evaporation and soil wetness during the monsoon and on annual basis (Lal and Chander,
1993). A case study in Orissa and West Bengal estimates that in the absence of protection,
one meter sea level rise would inundate 1700 km2
of predominantly prime agricultural land
(IPCC, 1998). In another study, it was found that in the absence of protection, a one meter sea
level rise on the Indian coastline is likely to affect a total area of 5763 km2
and put 1.7
million people at risk.
The regional effects of climate change on various components of the hydrological cycle,
namely surface runoff, soil moisture and evapotranspiration for three drainage basins of
Central India have been analyzed. Results indicated that the basin located in a comparatively
drier region is more sensitive to climate changes (Mehrotra, 1999).
The quantity of surface run-off due to climate change would vary across the river basin as
well as sub-basins in India. However, there is general reduction in the quantity of the
available run-off. An increase in precipitation in the Mahanadi, Brahimani, Ganga, Godavari
and Cauvery is projected under the climate change scenario. However, the corresponding
total runoff for all these basins does not increase. This may be due to increase in ET on
account of increased temperature or variation in the distribution of rainfall. In the remaining
basins, a decrease in precipitation was noticed.
Sabarmati and Luni basins show drastic decrease in precipitation and consequent decrease of
total runoff. This may lead to severe drought condition in future. The analysis has revealed
that climate change scenario may deteriorate the condition in terms of severity of droughts
and intensity of floods in various parts of India (Chadha, 2003).

50
Problems in groundwater management in India have potentially huge implications due to
global warming. The most optimistic assumption suggests that an average drop in
groundwater level by one meter would increase India‟s total carbon emissions by over 1%,
because the time of withdrawal of the same amount of water will increase fuel consumption.
The current simulation results from GCMs are still considered uncertain. Ability of present
GCMs in predicting the impact of climate change on rainfall is still not promising. In
addition, there are uncertainties involved in predicting extreme flood and drought events by
these models. While climate models predict an increase in precipitation by 24% to 15% over
India, regional changes may be different (Chottopadhya and Hulme, 1997). Studies on inter-
annual and long-term variability of monsoon and annual rainfall have indicated that variation
in rainfall for the subcontinent is statistically significant. Analysis of observed rainfall data
for the 131 years period (1871-2001) suggests no clear role of global warming in the
variability of monsoon rainfall over India (Kripalani et al., 2003). In that perspective, it is
difficult to convince the water planner and development agencies to incorporate the effect of
climate change into their projects.
Changes in cropping pattern and land-use pattern, over-exploitation of water storage and
changes in irrigation and drainage in the Gangetic basin show a reduction in the Ganges
discharge by 60% over 25 years. This has laid to about 50% drop in water availability in
surface water resources, drop in groundwater table and generation of new surface features
having different thermal properties (Adel, 2002).
Considering the inter-annual variability of rainfall in India, assessment of only volume may
not be helpful until temporal and spatial variations of climate change and their impacts are
assessed. Agricultural demand, particularly for irrigation water, which is a major share of
total water demand of the country, is considered more sensitive to climate change. A change
in field level climate may alter the need and timing of irrigation. Increased dryness may lead
to demand, but demand could be reduced if soil moisture content rises at critical times of the
year. It is projected (Doll and Siebert, 2001) that most irrigated areas in India would require
more water around 2025 and global net irrigation requirements would increase relative to the
situation without climate change by 3.5% - 5% by 2025, and 6% – 8% by 2075. In India,
roughly 52% of irrigation consumption across the country is extracted from groundwater;
therefore it can be an alarming situation with decline in groundwater and increase in
irrigation requirements due to climate change. Indian region is highly sensitive to climate
change. The elements/sectors currently at risk are likely to be highly vulnerable to climate
change and vaiability.

51
3.3 Nepal
Nepal is a land locked country between India and China. It contains 8 of the 10 highest
mountain peaks in the world, including Mount Everest (8848 m), although some of its low
lying areas are only about 80m above sea level. There is therefore extreme spatial climate
variation in Nepal – from a tropical to artic climate within a span of only about 200 km (the
size of an average grid box in a climate model). Nepal is divided into five geographical
region: Terai plain, Siwalik hills, Middle Mountains, High Mountains and the High
Himalayas.
A heavy reliance on tourism and agriculture makes Nepal‟s economy very sensitive to
climate variability (World Bank, 2002). It is difficult to determine Nepal‟s potential to adapt
to climate change. While only 31% of Nepal‟s 13,223 km of highway are paved, this
percentage is almost twice that for other low income countries. While greater number of
roads or a greater percentage of paved roads might imply a level of development, it might
also imply increased social exposure to climate hazards. For example, development of
highways along river valleys in particular might encourage settlements in regions that are
most vulnerable to flooding from extreme precipitation or glacial lake outbursts. Nepal‟s
electricity infrastructure is heavily reliant on hydroelectric power. Nearly 91% of the power
comes from this source. Hydroelectric plants are highly dependent on predictable runoff
patterns. Therefore, increased climate variability, which can affect frequency and intensity of
flooding and droughts, could affect Nepal severely.
Recent climatic trends reveal a significant warming trend in recent decades which has been
even more pronounced at higher altitudes. Climate change scenarios for Nepal across
multiple general circulation models show considerable convergence on continued warming,
with country averaged mean temperature increases of 1.2o
C and 3o
C projected by 2050 and
2100. Warming trends have already had significant impacts in the Nepal Himalayas – most
significantly in terms of glacier retreat and significant increases in the size and volume of
glacial lakes, making them more prone to Glacial Lake Outburst Flooding (GLOF).
Continued glacier retreat can also reduce dry season flows fed by glacier melt, while there is
moderate confidence across climate models that the monsoon might intensify under climate
change. This contributes to enhanced variability of river flows.
The climate in Nepal varies from the tropical to the arctic within the 200 km span from south
to north. Much of Nepal falls within the monsoon region, with regional climate variations
largely being a function of elevation. Mean temperature hover around 15o
C, and increase
from north to south with the exception of mountain valleys. Average rainfall is 1500 mm,
with rainfall increasing from west to east. The northwest corner has the least rainfall, situated

Report on south asian integrated water management imperative

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Report on south asian integrated water management imperative