presentation on environmental flow...

1. Minimum Flow- Need &
Response
Deepak Upadhyay
AHEC,IIT Roorkee
En. Id- 15512011
Mb. No- +919758495784

2. Contents
• Definition
• Why e-flow
• Significance of flow regulation
• Implementation Challenges
• Roles in implementation
• Legislative Prospective
• How much E-flow
• Method of e-flow measurement

3. Minimum Flow
Ideally - A river has right to all its flows
In reality - Flows that should be left in the river
• To allow the river to complete its hydrological cycle
• To Carry out various ecological and evolutionary processes
• To enable all beings including humans to benefit from the ecosystem
services provided by the river and its flows
• “Environmental Flows describe the quantity, quality and timing of
water flows required to sustain freshwater and estuarine ecosystems
and the human livelihoods and well being that depend on these
ecosystems”

4. • Fragmented rivers with ‘no flows’ in between dams
• deteriorating water quality
• Food plain farming under threat
• Fish catch and fisheries on the decline
• Riparian ecosystems losing continuity and
diversity
• Flows not reaching the delta and seas
• Salinity traveling deep inland
Why Minimum-flow

5. Cont…
Cont…

6. Cont…
Indus
• 1892 – 1990s – flows reduced from 1,85,000 MCM to 12,300 MCM
per annum - Reduced flows into delta – shrimp, mangroves, fish
productivity reduced , salinization increased , delta farming affected -
Salinity intrusion 64 km – 1.2 million acres farmland lost.
Krishna
• outfalls are falling over the years from 57 BCM before 1960s to
almost nil in 2004 impacting the coastal ecosystems
Yamuna
• no freshwater flows downstream of Tajewala upto Etawah, where
Chambal River meets Yamuna, during the lean months

7. Flows are affected - reasons are many
• Dams - block, fragment and regulate flows – time, magnitude,
duration and frequency of flows
• Diversion of water – complete / partial diversion of river/ stream -
• Deforestation - Degradation of the river catchment leading to reduced
flows – Most of the rivers
• Mining in the catchments
• Sand mining on river bed – Western Ghats rivers
• Pollution – Yamuna
• Glacial melt – climate change - Gangotri

8. Flows and deforestation

9. Paradise lost

10. Significance of flow regulation
• Ecological – aquatic biodiversity, feeding and breeding and habitats
affected , invasion of exotic and introduced species
• Morphological – sand, silt and sediment deposit declining, channel
• Hydraulic connectivity – lateral and horizontal connectivity disrupted
• Social issues – deteriorating water quantity and quality leading to
drinking water scarcity
• Economic – loss from fisheries and farming to the river communities
and the state
• Spiritual and cultural needs - sacred groves, temple fish sanctuaries

11. Implementation Challenges
• Hydrologically and ecologically different river systems
• Direct dependence on rivers very high
• Lack of valid, pre dam hydrological and ecological data and even if
present, deficient – lack of correlation with habitats
• Political priorities is a decisive factor
• Lack of awareness about flows – ecology – community linkages
• Need to address beyond project level to river basin level
• Institutional and policy challenges

12. Roles in implementation
• Governments at national and sub national levels - through new policy
frameworks - nature / river is also a ‘legitimate user of water’ and only
if water is left for nature can human needs be fulfilled.
• Research institutions and river experts - arriving at the optimum flows
including trade offs, incentives and alternatives
• Direct river dependent communities - learn from their wisdom and
integrate their experiences while setting flows.
• Voluntary organizations / NGOs/ community based organizations -
catalyst or mediator

13. Legislative Prospective
Section-3(3) of the Environment (Protection) Act,1986
Central Govt. empowered to constitute an authority or authorities for the
purpose of exercising and performing such powers and functions of the
Central Govt. under the Act.
Water Quality Assessment Authority notified by Central Govt.
mandated:
“To maintain minimum discharge for sustenance of aquatic life forms in
riverine system.”

14. Cont…
EIA, 1994/2006: Vested powers with the Govt. of India for granting
Environmental Clearance.
Section-24(1-b) of the Water(P&CP)Act,1974
Restricts entry into any stream of matter which may tend, either directly
or in combination with similar matters, to impede the proper flow of the
water of the stream in a manner leading or likely to lead to a substantial
aggravation of pollution due to other causes or of its consequences.

15. How much Minimum-flow
No simple figure can be given for the environmental minimum flow
requirement of river.
It is depend on two factors.
1. Objective based flow setting
2. Scenario based flow setting

16. 1.Objective based flow setting
“River flows are set to achieve specific pre-defined ecological,
economic or social objective. This is called objective based flow
setting.”

17. Cont…
it is related to a number of factors, including:
• Size of the river
• Its natural state
• A combination of the desired state of the river and, in practice, the
uses to which it is put.
(Consequently, before defining flow requirements, broader objective
must be determined to indicate the type of river desired)

18. Scenario based flow setting
For most river system of the world, no specific ecological objective
have been set. Furthermore, many regulatory authorities have to balance
the need of water users with environmental concerns.
“An alternative to the objective-based approach is for water managers to
examine various water allocation option, or scenarios. This is called
scenario-based flow setting.”
This is divided into four class.

19. Table ecological management classes
Class Description
A Negligible modification from natural conditions.
Negligible risk to sensitive species.
B Slight modification from natural conditions.
Slight risk to intolerant biota.
C Moderate modification from natural condition.
Especially intolerant biota maybe reduced in number and extent.
D High degree of modification from natural conditions.
Intolerant biota unlikely to be present.

20. Method of e-flow measurement
1. Hydrological methods,
2. Hydraulic rating methods,
3. Habitat Simulation methods, and
4. Holistic methods–Building block

21. Hydrological Method
• Hydrological methods assume a relationship between flow and
specific biological parameters
• This flow level can vary from a single fixed value to a number of
variable values.
• Primarily use hydrological data (historical monthly or daily flow
records) for making e-flow recommendations for maintaining river
health at designated level.

22. Hydrological methodologies: strengths and deficiencies
• Simple, rapid, inexpensive desktop approaches
• Low data needs, primarily flow data
• Suitable for water resource planning purposes
• Potential for regionalization for different river ecotypes
• Simplistic, inflexible, low resolution output
• Direct ecological links absent or limited (but recent advances made to
improve ecological relevance of flow indices and to set flow targets)
• Dynamic nature of flow regime seldom addressed
• Suitable for low controversy situations

23. Hydraulic Rating Method
• Hydraulic rating method assume a relationship between discharge and
various parameters of stream geometry such as width, depth and
wetted perimeter, based on surveyed river cross-section.
• Use changes in simple hydraulic variables (e.g. wetted perimeter)
across single river cross-section as surrogate for habitat factors
limiting to target biota.
• Generally hydraulic method are not suitable for the assessment of
seasonal flow requirement.

24. Habitat Simulation
Assess e-flows on basis of modeling of quantity and suitability of
physical habitat available to target species under different flow regimes
(integrated hydrological, hydraulic and biological response data).

25. Habitat simulation methodologies: strengths and
deficiencies
• High resolution habitat-flow relationships for target species
• Generate alternative e-flow scenarios for different species
• Advanced technical support
• Focus on target species, not whole ecosystem
• Not applicable for some ecosystem components
• Limited links with characteristics of flow regime
• Output restricted to flow-hydraulic habitat relationships
• Resource intensive relative to output
• Poor links with biological responses to flow change

26. Holistic Method
Identify important flow events for all major components of river,
model relationships between flow and ecological, geomorphological and
social responses, and use in interdisciplinary team approach to establish
recommended e-flow regime/implications of flow scenarios (bottom-up
or top-down.

27. Holistic methodologies: strengths and deficiencies
• Whole-ecosystem focus
• Generates alternative environmental flow scenarios for different
ecological and social conditions
• Use of interdisciplinary expert judgement in structured, consistent
process
• Usable in data rich and data poor contexts (use of available techniques
and understanding)
• Explicit links with characteristics of flow regime and with biological
and social responses to flow change
• Reliant on expert judgement
• Difficulties in reconciling opinions of different experts
• Moderate to high resource

28. Reference
• http://www.iwmi.cgiar.org/Publications/IWMI_Research_Reports/PDF/PUB114/R
R114.pdf
• Table 1: Environmental Management Classes of rivers for setting eflows
objectives: Adapted from IIT Roorkee. (2011) Assessment of Cumulative Impacts
of Hydroelectric projects in Alaknanda-Bhagirathi basins. Report prepared by
AHEC, IIT, Roorkee. Submitted to the Ministry of Environment and Forests,
Govt. of India.
• http://www.hydrol-earth-syst-sci.net/8/861/2004/hess-8-861-2004.pdf
• 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 Volume 19, Issue 5-6,
pages 397–441.

29. THANK YOU !