This lecture covers environmental flow and its inter-relationship with the integrated water resource management. Environmental flow allows for meeting the water needs of the aquatic ecosystems.

1. Inter-Linkages between Integrated Water Resource
Management and Environmental Flows for Ensuring
Water Security for All

2. Water Stress
Water stress occurs when the demand for water exceeds the available amount during a certain
period or when poor quality restricts its use. Water stress causes deterioration of freshwater resources
in terms of quantity (aquifer over-exploitation, dry rivers, etc.) and quality (eutrophication, organic
matter pollution, saline intrusion, etc.)
Water scarcity refers to the volumetric abundance, or lack thereof, of water supply. This is typically
calculated as a ratio of human water consumption to available water supply in the given area.
Water scarcity is a physical, objective reality that can be measured consistently across regions and
over time.
Falkenmark Indicator: An indicator used to measure water scarcity. It
measures water scarcity as the amount of renewable freshwater that is available per person
per year and proposes a threshold of 1,700 m3 per person per year to identify the regions
that suffer from water stress.
Source: http://epaedia.eea.europa.eu/alphabetical.php?letter=W&gid=108#viewterm
https://pacinst.org/water-definitions/; https://unece.org/DAM/env/europe/monitoring/Indicators/C-1-en-final.pdf
As per 2011 Census, per capita water availability in India is
1575 m3
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3. Water Resource System
• A water resource system encompasses surface water, ground
water, riverbed, riverbanks and technical infrastructure,
including the occurring plant and animal communities and all
associated physical, chemical and biological characteristics
and processes
• Watershed centric approach is critical for ensuring water
security in the urban areas
• Water resource system includes three groups of functions: (i) Sink,
(ii) Source and (iii) Life Support system
Source: https://www.chegg.com; https://www.britannica.com/technology/irrigation; https://thewire.in/environment
Sink Source Life Support system
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4. Integrated Water Resource Management
• IWRM is a process which promotes the
coordinated development and
management of land, water and related
resources in order to maximize the
resultant economic and social welfare in
an equitable manner without
compromising the sustainability of vital
ecosystems
• IWRM addresses the three E’s: Economic
efficiency, Environmental sustainability
and social Equity, including poverty
reduction
• IWRM acts as the link between the
water needs of the ecosystem and the
humans
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Source: Guidelines for IWRM, 2016; www.gwp.org
Basin
Organisation
Technology
Basin Level
Management
Activities
Stakeholder
Involvement
Human and
Organisational
Capacity
Science
Based
Decision
Making
Policy, Legal
and Regulatory
Framework
Human
Water
Needs
IWRM
Availability of
fresh water
of appropriate
quality
Aquatic
Ecosystem
and
Biodiversity
needs
Appropriate
Flow
to Coastal
Areas
Climate
Geology
Vegetation
Topography
Basin
Organisation
Technology
Basin Level
Management
Activities
Stakeholder
Involvement
Human and
Organisational
Capacity
Science
Based
Decision
Making
Policy, Legal
and Regulatory
Framework
Human
Water
Needs
IWRM
Availability of
fresh water
of appropriate
quality
Aquatic
Ecosystem
and
Biodiversity
needs
Appropriate
Flow
to Coastal
Areas
Climate
Geology
Vegetation
Topography

5. Environmental Flow
Environmental
Flows
Ensure Water for
Ecosystem needs
Maintain water
quality at
acceptable levels
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• Environmental Flow is defined as the quantity,
timing, and quality of freshwater flows and
levels necessary to sustain aquatic ecosystems
which, in turn, support human cultures,
economies, sustainable livelihoods, and well-
being
• In India, the scope of environmental flows is
limited to the terms called ‘minimum flow’ and
‘flushing flow’
• Under the basic principles of Draft National
Water Framework Bill, 2016, it is mentioned
that environmental flows adequate to preserve
and protect a river basin as a hydrological and
ecological system shall be maintained and a
portion of river flows should be kept aside to
meet ecological needs ensuring that the low and
high flow releases are proportional to the
natural flow regime, including base flow
contribution.
• Meeting the aquatic ecosystem needs means
those of the groundwater and the surface water
dependent ecosystems. If the River dies then it is
detrimental to all the water dependent
communities, not just rural but also the urban.
Source: Brisbane Declaration,2018; Central Water Commission. (2007)

6. Status of Water Resources in India
• For large-scale analyses of water resources, the
country is often separated into 19 major river
basins/ drainage regions
• Basins including Cauvery, Ganga-Brahmaputra,
Godavari, Indus, Krishna, Mahanadi, Narmada,
Pennar and Tapi have been categorized as
“strongly affected” by flow fragmentation and
regulation through dam construction
Source: NCIWRDP, (Nilsson et al. 2005)
Estimation of Water Deficit in the case of India (year 2050)
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7. Status of Water Resources in India
• Over abstraction of ground water has obstructed
the base flow to the surface water bodies thus
substantially reducing in turn the environmental
flow requirements
• Stage of ground water extraction is defined as the
ratio of existing ground water extraction for all
uses to annual extractable ground water
resources represented in percentage
• Annual extractable ground water is considered as
90-95% of the annual recharge
• Stage of ground water extraction in the range of 0-
70% is considered as safe, 70%-90% as semi-
critical, 90%-100% as critical, and >100% as over
exploited
• Groundwater scenario ranges from semi critical to
over exploited in many development blocks
concentrated mainly in the western and southern
regions
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Source: C.G.W.B (as on 2017)

8. Environmental Flow Assessment
Methodologies
• Environmental flow assessments are
performed mainly for the river systems that
are already regulated or are the focus of
proposed water resource developments
• The scale at which the environmental flow
assessment is undertaken may also vary
widely, from a whole catchment for a
large river basin that includes regulated
and unregulated tributaries, or a single
river stretch
• Different methodologies are appropriate
over such a broad range in spatial scale and
resolution, as well as in accordance with
constraints including the time frame for
assessment, the availability of data,
technical capacity and finances
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Source: Arthington et al., 2000; King et al., 1999; Tharme, 2003; Arthington et al., 1998; https://www.globosurfer.com/river-velocity/;
https://mammothmemory.net/geography/geography-vocabulary/river-landscapes-2/cross-profile.html; https://www.earth.com/news/warm-river-habitats-are-
important-for-cold-water-fish/; https://www.thehansindia.com/telangana/telangana-varsities-fight-shy-of-multidisciplinary-studies-697396;
https://en.wikipedia.org/wiki/Olentangy_River Hydrologic
• Hydrologic
Data
Hydraulic
• Hydraulic
Data
Holistic
• Multidisciplin
ary expertise
and input
Habitat
Simulation
• Quantity and
suitability of
instream
physical
habitats
available

9. Interlinkage between Environmental Flows and
IWRM
• As far as the environmental flow assessment is
concerned, a shift is needed from the concept of
‘minimum flows’ and ‘flushing flows’ to a set of flow
variables more accurately representing the natural
variations in the flow regime temporally
• By maintaining the quality of the drinking water
sources such as the rivers and its tributaries at a better
level in turn reduces the capital costs incurred for
setting up of water treatment infrastructure substantially
• Environmental flow assessment findings, if
implemented will also be helpful in improving the
ground water recharge, as part of the water
inundating the floodplains, eventually becomes the
ground water
• Trade-offs between various water uses such as
drinking water, irrigation, ecosystem needs and
industrial are required for better determination of
environmental flows
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10. References
• Nilsson, C., et al., (2005). Fragmentation and flow regulation of the world’s largest river systems. Science, 308,
405–408. [Crossref]
• Arthington, A. H., & Zalucki, J. M. (1998). Comparative evaluation of environmental flow assessment techniques:
Review of methods. LWRRDC Occasional Paper Series 27/98, 141.
• Tharme, R. E. (2003). A global perspective on environmental flow assessment: Emerging trends in the development
and application of environmental flow methodologies for rivers. River Research and Applications, 19(5–6), 397–
441. https://doi.org/10.1002/rra.736
• King, J., Tharme, R. E., & Brown, C. (1999). Definition and implementation of instream flows. Thematic Report to
the World Commission on Dams. Southern Waters Ecological Research and Consulting, Cape Town, South Africa,
94 p.
• Arthington, Angela H., et al. "Environmental flow requirements of the Brisbane River downstream from Wivenhoe
Dam." Southeast Queensland Water Corporation and Centre for Catchment and In-Stream Research:
Brisbane (2000)
• Brisbane Declaration on Environmental Flows (2018)
• Central Water Commission. (2016). Guidelines for Integrated Water Resource Management
• Central Water Commission. (2007) Report of Working Group on Environmental Flows
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