Avinash kafle M. Sc. Forestry Agriculture and Forestry University Faculty of forestry, Hetauda, Nepal

1. (A Term paper presentation on Advance Watershed Management-601 SWM)
Basic Concept of Basin, Watershed, Sub watershed
and Micro watershed in Nepalese context
Avinash Kafle
Roll no: 5/2079-2081
M.Sc. forestry
Agriculture and Forestry University
Faculty of Forestry
Hetauda, Nepal
11 September , 2023
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2. Outline of Presentation
 Introduction
 Objectives
 Methodology
 Findings and Discussions
 Conclusion
 References
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3. Introduction
• A basin is a large land with a number of watersheds.
• The river basin is the portion of land drained by a river
and its tributaries encompassing all of the land surface
dissected and drained by many streams and creeks that
follow downhill into one another.
• The major river basins of Nepal can be broadly divided
into four major systems, Koshi (or Saptakoshi) in the east,
Narayani (or Gandaki) in the central, Karnali in the west
and Mahakali in the far west.
• There are five small sub-basins viz. Bagmati, kankai,
Kamala, West Rapti and Babai which originate in the
Mahabharat Range (National water plan, 2003) .
• Whole Nepal is a part of the Ganga Basin and it is
estimated that approximately 70% of dry season flow and
40% of annual flow of the Ganga river comes through
Nepal.
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4. Contd..
• Watershed is broadly termed as any surface area
from which runoff resulting from rainfall is collected
and drained through a common point (into a stream,
a channel, a lake, a reservoir, or other body of water)
which is synonymous with a drainage basin or
catchment area (UN conference, 1977).
• Unless a watershed discharges directly into the
ocean, it is physically a part of a larger watershed
that does, and may be referred to as sub watershed
(Black 1991).
• Watersheds vary from a few hectares to thousands of
square kilometers.
• Two or more catchments form sub-watersheds.
• A group of sub watersheds form a watershed.
• A group of watersheds form a basins.
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5. Contd..
Watershed management unit Typical Area(Km2)
Micro watershed 0.05-0.50
Sub watershed 1-10
Watershed 10-100
Sub-basin 100-1,000
Basin 1,000-10,000
Classification of Watersheds of Nepal
Source: World Bank, 2008
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6. Contd..
• For Nepal, 5 to 25 km2 sub-basin areas have been
suggested as the size range of a sub-watershed (Achet,
1998).
• Micro-watershed is the smaller sub-division of watershed
consists of smaller catchment for purposes of better
resource management and conservation.
• This is the scale at which detailed studies and local
planning are done.
• The whole basin is divided into several smaller units,
such as watersheds or sub-watersheds, by considering its
drainage system.
• Thus, watersheds are composed of numerous, small units
of sub-watershed which are smaller in size.
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7. Objectives
To know about the basic concept of basin, watershed, sub watershed and
micro watershed of Nepal .
Methodology
This review paper was prepared on the basis of information collected
from secondary data sources like relevant articles, journals, government
documents, thesis reports and internet surfing.
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8. Four Major River basins of Nepal
Source: WWF, Nepal
1. Koshi River Basin
• The Koshi flows inside the eastern part of
Nepal. It is the biggest river system in Nepal.
• It is a Transboundary river originating from
high Himalayas and Tibetan plateau.
• It has a total drainage area of about 60,400 sq.
km in Tibet, Nepal and Bihar out of which
27,863 sq. km lies within Nepal (WECS,
2002).
• Its Seven tributaries- the Sunkoshi, Indrawati,
Dudh koshi, Tamakoshi, Likhu, Arun and
Tamor- give it the name Sapta koshi ( Bista,
2014).
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Findings and Discussions

9. Contd..
2. Gandaki River basin
TY - BOOK
Adapted from Dandekhya et al., 2017
• The Gandaki river basin is a transboundary basin
lying north-south in central Himalayan region.
• It has catchment area of 34,960 sq. km lies in both
Nepal and China and 29,626 sq km lies within
Nepal (WECS, 2002).
• The Gandaki river is known as Narayani in the
plains of Nepal and as the Gandak in India where it
joins the Ganges (Ganga) near Patna.
• It is also called ‘Sapta Gandaki’ because of its
seven sub-basins, namely Trishuli, Kaligandaki,
Budhigandaki, Daraundi, Setigandaki, Madi and
Marshyagdi.
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10. Contd..
• Karnali river is the longest river (507
km) flowing through Nepal along with
other snow-fed rivers constitute Karnali
river system.
• The drainage area of Karnali River is
43,679 sq. km of which around 95% (
i.e., 41,058 sq. km) lies in Nepal (Panthi
et al. 2018).
• Six sub-basins of the Karnali are:
 Sani Bheri
 Thuli Bheri
 Humla Karnali
 Mugu karnali
 Budhi Ganga
 Seti
3. Karnali River Basin
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11. Contd..
• The Mahakali river originating from Api Himal and Trans
Himalayan region and is called by various names viz. kali,
Mahakali, Sharda along its course falling in india and
Nepal.
• It has total catchment area of 15,260 sq. km of which 35.4%
(i.e., 5,317 sq. km) lies on Nepal (WECS, 2002)..
• Two major sub basins of Mahakali on Nepalese side are:
 Chamelia
 Surnagad
4. Mahakali River Basin
(Source: Bagale, 2019)
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12. Status of Watersheds and sub-watersheds of Nepal
• According to Singh and Kharel (2004), it is
reported that about 10% of Nepal's area was
covered with "much degraded” watersheds, 19%
to be marginally degraded while only 33% of the
country was under “very good condition”
watersheds.
• A study done by Shrestha and Manandhar (2020) from eight micro-watersheds in Khageri Khola
revealed 56 water sources as sub-watershed in Chitwan that were found decreasing with moderate
(43%) to insufficient (32%) amount of water available for drinking where tap water and tube
wells collectively fulfilled the water demand to 43% and 38% respectively.
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13. Contd..
Watershed
conditions
Proportion of land
Good 33%
Fairly Good 35%
Marginal 19%
Poor 3%
Very Poor 10%
Watershed Conditions in Nepal
Source: DSCWM, 1983
Source: DSCWM
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14. Contd..
• Management of the watershed resources needs an integrated approach to manage land,
enhance the soil productivity, control erosion, water conservation, vegetation growth
taking consideration of various socio-economic factors (Campbell, 2016).
• Large watersheds are divided into sub-watersheds for the collection of sufficient bio-
physical and socio-economic information which is required for integrated watershed
management.
• Sub-watershed is prepared in order to minimize natural and human-induced hazards
and to conserve valuable resources (soil, water, biodiversity and socio-cultural
aspects).
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15. Major Issues
• Nepal’s watersheds have not been properly evaluated according to their resource
endowment and degree of fragility.
• The hills and mountains of Nepal are the watershed areas with the most fragile ecosystem
and poor agricultural potential because of their steep slopes, fragile mountain geology, and
poor soil profile (Pandit and Thapa, 2004).
• Priority should be given to integrated watershed management to conserve the underground
water and soil in the Chure-Bhawar and Terai areas by coordinating the work of agriculture
and water resources sectors (NPC, 2003).
• Siddiqui et al., 2012 stated that Upper Karnali watershed, Mugu Karnali Watershed and
Budhi Ganga Watershed of the Karnali river basin are the most vulnerable towards the
climate change due to which they are at higher risk from hazards like landslides, flood,
sedimentations, droughts, food insecurity and frequent intensive rainstorms.
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16. Conclusions
• Many of Nepal’s watersheds are in a state of physical and biological deterioration
where soil erosion and watershed degradation problems have caused adverse impacts
on the socio-economic condition of the country and its people.
• Management interventions of watersheds in micro-watershed level, land tenure could
be better analyzed and solutions more readily worked out.
• The concept of sub-watershed prioritization plays a key role in identifying areas that
need immediate attention.
• While planning, monitoring & implementing soil and watershed management,
strategies should be prioritized based on the principles of integrated watershed
management.
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17. References
• Achet, S. H. 1998. An ecosystem approach to integrated resource management: Building from
experience in participatory watershed management in Nepal. In Proceedings of International
Seminar on Sustainable Forest Management (pp. 268-274).
• Bista, A., 2014. Flood Warning System for the Koshi River Basin. Cologne University of
Applied Sciences.
• Black, P. e. 1991. Watershed Hydrology. englewood Cliffs, n.J.: Prentice hall.
• Dandekhya et al., 2017. The Gandaki Basin - Maintaining Livelihoods in the Face of
Landslides, Floods, and Drought. DO - 10.13140/RG.2.2.17756.28802
• DoFRS. 2017. Department of Forest Research and Survey, Kathmandu, Nepal.
• DSCWM. 1983. Watershed condition of the districts of Nepal. Kathmandu, Nepal, Department
of Soil Conservation and Watershed Management (DSCWM).
• NPC. 2002. Tenth Plan His Majesty’s Government National Planning Commission Nepal.
• Pandit, B. H., Thapa, G. B. 2004. Poverty and resource degradation under different common
forest resource management systems in the mountains of Nepal. Society and Natural
Resources, 17(1), 1-16.
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18. Contd..
• Panthi, J., Khatiwada, K., Shrestha, M. L., & Dahal, P. (2018). Water poverty in the context of
climate change: a case study from Karnali river basin in Nepal Himalaya. International
Journal of River Basin Management, 1-16. doi: 10.1080/15715124.2018.1531421
• Petersen, M. M. 1999. A natural approach to watershed planning.
• Shrestha, P., Manandhar, B. 2020. Status, Importance and Major Issues in Water Source in
Watershed of Chitwan, Nepal. Journal of Institute of Forestry Nepal., (Vol 17 2020).
https://doi.org/10.3126/forestry.v17i0.33628
• Siddiqui, S., Bharati, L., Panta, M., Gurung, P., Rakhal, B., & Magarjan, L. D. (2012). Climate
change and vulnerability mapping in Watersheds in Middle and High Mountains of Nepal.
Department of Soil Conservation and Watershed Management (DSCWM), Government of
Nepal.
• Singh, S. L., Kharel, B. P. 2004. Watershed Management Case Study: Nepal: Review and
assessment of watershed management strategies and approaches. Food and Agriculture
Organization Of The United Nations: Rome, Italy.
• World Bank (2008). Watershed Management Approaches, Policies, and Operations: Lessons
for Scaling Up.
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19. Thank You!!
Feedbacks and Suggestions are
Appreciated.
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