In the Name of God Sharif University of Technology Environmental Flows

BY: Somayeh Sima PhD student of SUT Contents

„ Definition of EWR

„ Literature Review

„ EF methodologies

„ EWR of wetlands

„ Successful implementation of EWR

„ Conclusion

„ References What Is an Environnemental Flow?

Environmental flow is the water regime provided within a river, wetland or coastal zone to maintain ecosystems and their benefits where there are competing water uses and where flows are regulated.

The outcome is an improved management regime that guarantees the longevity of the system and finds the optimal balance between the various uses.

Source: FLOW, The Essentials of Environmental Flows, IUCN-WANI, 2003 TERMINOLOGYTERMINOLOGY

¾ "Environmental"Environmental flows"flows"

¾ InstreamInstream flowflow requirementsrequirements ((IFRsIFRs))

¾ MinimumMinimum flowflow

¾ ““EnvironmentalEnvironmental WaterWater””

¾ EcologicalEcological FlowsFlows ImportanceImportance ofof EWREWR Ecosystem’s Values: Direct values

• Private goods or commodity values • Harvested –Meat – Fuel wood/timber – Edible/medicinal plants • Consumptive and productive use Ecosystem’s Values: Indirect values

• Public goods, nonconsumptive use value • Benefits from biodiversity not involving harvesting – Ecosystem productivity – Water quality – Soil protection – Climate – Flood control – Waste treatment and nutrient retention NaturalNatural FlowFlow RegimeRegime ofof aa RiverRiver Ecological Functions of River Flows

Extreme low (drought) flows Population regulation; life history cues Low (base) flows Provide habitat for aquatic biota, maintain water temperature and water chemistry, provide drinking water for terrestrial animals Higher flows Shape river channel, prevent encroachment of riparian vegetation, flush sediments and pollutants, maintain estuaries Large floods Provide biological cues, connect river with floodplain, purge invasive species and maintain species balance Lack of minimal discharge results in severe pollution of the Vishnumati river in Kathmandu (Nepal). The Role of Wetlands in Water

Control city Wetland present:

upland rivers and river streams wetland Lake •fed by rain •traps water •large variation in •releases water •maintains steady flow water amount slowly •during dry periods •further downstream •downstream rivers wetland supplies extra = greater flow keep steady flow water •(more tributaries •during wet periods added) wetland absorbs water The Role of Wetlands in Water

Control city Wetland absent:

No wetland

•During wet periods, nothing stops water flow •larger and larger amounts of water flow as you move downstream •river will flood more often, more severely •with greater flooding comes greater erosion -- leads to further destruction of area •this requires extensive (and expensive) flow regulation with concrete and dams Flow-Regulation Functions of a Wetland

¾ wetland slows water flow ¾ this causes sediments to be dropped ¾ sediments collect, more trapping occurs ¾ since flat, water spreads laterally ¾ water trickles down to recharge underground aquifers WhatWhat DoDo EnvironmentalEnvironmental FlowsFlows AimAim ToTo Achieve?Achieve?

¾ Biodiversity objectives Biodiversity objectives deal with biological components of the system – the ultimate outcome of the environmental flows. Examples: ƒ desired condition of individual species ƒ desired condition of an entire community of migratory fish or macroinvertebrates ƒ desired condition for Spawning or migration ¾ Flow objectives Flow objectives deal with the flow regime itself. The main aim of the flow objectives is to explicitly describe the environmental flow (i.e. low flows, freshes) that will achieve the biodiversity objectives, such as spawning. Origins of the concept

‰ Major river alterations occurred in the US during the middle of the last century

‰ Water flowing to the sea is wasted! – Dam building frenzy in the 1950s-1960s – Nearly 200 large dams built per year in the US during this period.

‰ Many dams didn’t leave any water in river channels for downstream ecosystems and other users. History

¾ Concerted development of methodologies for prescribing EFRs began at the end of the 1940s, in the westernUnited States of America. Dramatic progress was achieved during the 1970s, primarily as a result of new environmental and freshwater legislation and demands from the water planning community for quantitative documentation of EFRs (Stalnaker, 1982; Trihey and Stalnaker, 1985), in concert with the peak of the dam-building era (WCD, 2000). Outside the United States, the route by which environmental flow methodologies (EFMs) became established for use is less well documented (Tharme, 1996).

¾ Environmental water allocation for wetlands associated with river systems has frequently been incorporated into the flow allocation process for the river system [eg, the Murrumbidgee wetlands (Shields, 1998)]. CurrentCurrent SituationSituation

¾ More than 60% of the world’s rivers are fragmented by hydrologic alteration.

¾ The total global value of ecosystem goods and services is estimated at US$ 33 trillion per year of which roughly 25% relate directly to freshwater ecosystems . (WCD 2000) ProblemsProblems

¾¾InIn mostmost watersheds,watersheds, riverriver flowsflows areare highlyhighly regulatedregulated ¾¾ProjectedProjected demandsdemands areare changingchanging andand substantialsubstantial relativerelative toto existingexisting suppliessupplies ¾¾StrategiesStrategies reflectreflect primarilyprimarily utilizationutilization ofof existingexisting surfacesurface waterwater resources;resources; nono majormajor surfacesurface waterwater developmentdevelopment DistributionDistribution ofof WaterWater UseUse throughoutthroughout thethe WorldWorld EWR Assessment in an International Scale AnAn OverviewOverview ofof thethe WorldWorld SituationSituation WhatWhat isis thethe Question?Question?

For a relatively pristine river being considered for development: – How much alteration of natural flows is too much?

For a river that is already degraded and ecological health needs to be restored: – How much restoration of flow is enough? HowHow ToTo EstablishEstablish EnvironnementalEnvironnemental FlowsFlows ??

¾ DefineDefine waterwater requirementsrequirements ((definingdefining objective,objective, selectingselecting tradetrade offsoffs scenariosscenarios andand EFEF methodmethod)) ¾ ModifyModify waterwater infrastructureinfrastructure ¾ FinanceFinance ¾ CreateCreate aa policypolicy andand legallegal frameworkframework ¾ GenerateGenerate politicalpolitical momentummomentum ¾ BuildBuild capacitycapacity forfor designdesign andand implementationimplementation MethodologiesMethodologies ForFor SettingSetting EFEF ¾ Hydrological methods: they are mainly desktop approaches relying primarily on historical flow records to make flow recommendations for the future. Little, if any, attention is given to the specific nature of the considered river or its biota.For instance Q90,7Q10,.

¾ Hydraulic rating methods: they use the relationship between the flow of the river (discharge) and simple hydraulic characteristics such as water depth, velocity, or wetted perimeter to calculate an acceptable flow.

¾ Habitat simulation methodologies: They are based on the determination of habitat preference curves for species. Habitat availability is modeled for change in discharge.

¾ Holistic methods: they require collection of considerable river- specific data and make structured links between flow characteristics of the river and the flow needs of the main biotic groups (fish, vegetation, invertebrates). CalculationCalculation ofof 7Q107Q10

Year 7-Day Rank Q P T MinFlow(cms) 11.484.7621.00 1971 1.72 21.659.5210.50 1972 3.03 3 1.72 14.29 7.00 1973 2.76 4 1.87 19.05 5.25 1974 1.65 5 1.92 23.81 4.20 1975 2 6 2 28.57 3.50 1976 4.23 7 2.14 33.33 3.00 1977 4.11 8 2.47 38.10 2.63 1978 1.92 9 2.5 42.86 2.33 1979 2.14 10 2.76 47.62 2.10 1980 1.48 11 2.84 52.38 1.91 1981 4.48 12 3 57.14 1.75 1982 3.03 13 3.03 61.90 1.62 1983 2.84 14 3.03 66.67 1.50 1984 3.66 15 3.07 71.43 1.40 1985 1.87 16 3.66 76.19 1.31 1986 5.39 17 4.11 80.95 1.24 1987 3 18 4.23 85.71 1.17 1988 2.5 19 4.48 90.48 1.11 1989 2.47 20 5.39 95.24 1.05 CalculationCalculation ofof 7Q107Q10 MethodsMethods’’ OutputOutput

Prescriptive Interactive Often provide a single flow regime to Provide a range of flow regimes, each maintain a single objective (river linked to a different river condition. condition). Motivate for the inclusion of specific Explain the consequences of flow parts of the flow regime. manipulations.

Not conducive to exploring options. Conducive to exploring options.

Suited for application where objectives Suited for application where the are clear and the chance of conflict eventual environmental flow is an is small. outcome of negotiations with other users. ApplicationApplication ofof DifferentDifferent MethodsMethods

A global review of the present status of environmental flow methodologies revealed the existence of some 207 individual methodologies, recorded for 44 countries within six world regions. Hydrological Methods (TENNANT METHOD)

Recommended percentage of AAF Objective Autumn-Winter Spring-Summer Flushing or maximum flows 200 200 Optimum range of MF 60-100 60-100 Percentage AAF required to maintain a required river condition Outstanding 40 60 Excellent 30 50 Good 20 40 Fair or degrading 10 30 Poor or minimum 10 10 Severe degradation 10-zero flow 10-zero flow HydraulicHydraulic RatingRating ((WETTED-PERIMETER METHOD) HabitatHabitat SimulationSimulation Downstream Response to Imposed Flow Transformation (DRIFT) • Identifies the different degrees of ecological health that would be expected as existing flow conditions in a river were either increasingly altered or restored • Uses a classification system to determine desired levels of ecological condition for a river basin.

Flow Targets ComparisonComparison ofof MethodsMethods

Relative Approximate Data and time confidence Level of Output Method duration of requirements In Experience assessment output Tennant Moderate to low Two weeks Low USA/extensive Method Wetted Perimeter Moderate 4 months Low USA/extensive Method Prescriptive South Africa, Expert Panels Moderate to low 1-2 months Medium Australia/ extensive Holistic Australia/ very Moderate to high 6-18 months Medium Method limited

IFIM Very high 2-5 years High USA,UK/extensive Interactive Lesotho, South DRIFT High to very high 1-3 years High Africa/very limited DifferenceDifference BetweenBetween EFEF andand WetlandsWetlands’’ EWREWR

¾ WhileWhile thethe determinationdetermination ofof environmentalenvironmental flowsflows forfor riversrivers generallygenerally occursoccurs atat largelarge scales,scales, withwith thethe examinationexamination ofof entireentire riverriver systems,systems, environmentalenvironmental waterwater allocationsallocations forfor wetlanwetlandsds maymay sometimessometimes occuroccur atat muchmuch smallersmaller spatialspatial scalesscales..

¾ therethere isis notnot suchsuch aa directdirect relationshiprelationship betweenbetween waterwater quantityquantity andand geomorphicgeomorphic processesprocesses inin wetlands.wetlands. ThereThere isis generallygenerally aa closeclose connecticonnectionon betweenbetween waterwater quantityquantity andand thethe spatialspatial extentextent ofof wetlandwetland habitat.habitat. Approaches to Set the Water Requirements Of Wetlands ¾ Top-down ¾ Bottom-up

¾ Hydrology–hydraulics driven ¾ Ecology-driven Methodologies to Set the EWR of Wetlands

Approach Major elements Hydrology- ƒ Determine the pre-development water regime driven using any existing data and/or modeling.

ƒ Attempt to restore this regime.

Ecology- ƒ Determine a water regime that will match the driven requirements of preferred or existing biological communities, or those which used to exist ComparisonComparison ofof thethe ApproachesApproaches

Approach Advantages Disadvantages Hydrology- ƒDoes not require knowledge about the ƒThe biota may have changed since driven water requirements of wetland plants and pre-development times due to causes animals not directly related to water regime ƒCosts low ƒDifficult to justify the determined water regime in trade-off situations ƒNot amenable to the development of conceptual models Ecology- ƒParticularly useful in the lack of ƒIs dependent upon knowledge about driven pre_disturbance hydrological data water need of wetland biota. ƒAimed at the protection of identified ƒRequires a large research effort or species detailed existing knowledge. ƒDirectly addresses the respective values ƒknowledge from one wetland of wetlands. environmental water allocation can't ƒKey hydrological elements of relevance be utilized for others in the same to biota may be identified region. Monitoring data (hydrological ƒUseful Where invasion of exotic species + biological) will add to the knowledge is directly related to the flow regime of the water regime responses of ƒThe determined EWR is defensible in wetland biota. trade-offs. ƒAmenable to conceptual modeling An Examples of hydrology-driven approaches

Ecosystem impact data Determine the hydrological 1. Generic relationships hydrology and divergence from the pre- hydraulics and habitat, function, development water regime. species 2. Site specific relationships hydrology and hydraulics and habitat, function, Identify possible hydrologic species management/irrigation measures

Socio-economic impact data cost reliability and restrictions and Model hydrologic divergence of above options water availability

Sensitivity analysis of management options Environmental risk vs. consumer risk

Non-hydrologic mitigations Trial / monitor review report adjust An Examples of ecology-driven approaches

1. Describe ¾ ecology ¾ hydrology ¾ uses and values

2. Set vegetation-related management objectives. Resolve internal trade-offs (within floodplain) e.g. grazing, conservation

3. Describe relationships between vegetation and water regime

4. Determine the water regime required to achieve management objectives

5. Trade-off process with other water uses. Resolve external trade-offs egg with irrigators

6. Implementation GeneralGeneral RulesRules

¾ The environmental-flow requirements set for the river upstream of a wetland may not be adequate to cater for the estuary’s water requirements.

¾ Of importance too for other aquatic ecosystems, It was found that it is not possible to extrapolate results from one wetland to another. Challenges for Environmental Flows

¾ Understanding of the socio-economic costs and benefits of environmental flows ¾ Water quality problems ¾ Groundwater interaction with surface water ¾ Marine ecosystems (tide effect) ¾ …. DesirableDesirable FeaturesFeatures ForFor aa SuccessfulSuccessful EnvironmentalEnvironmental FlowsFlows ImplementationImplementation

¾¾ PoliticalPolitical will,will, legislation,legislation, andand managementmanagement strategiesstrategies ¾¾ DataData andand toolstools ¾¾ SpecialistSpecialist expertiseexpertise ¾¾ FundsFunds ¾¾ TimeTime managementmanagement Conclusions

ƒ Environmental flows is an evolving concept and also a critical first step in IWRM.

ƒ People around the world are addressing the need for environmental flows in different ways

ƒ Hundreds of methods exist Conclusions

¾ Setting EF is not only the matter of water quantity, but also is the matter of flow timing and quality as well.

¾ From an IWRM perspective, its important to involve society directly in the decision- making process for setting environmental flows Reference Websites:

IWMI (International water management Institute) www.iwmi.cgiar.org IUCN (The World Conservation Union ) www.waterandnature.org WB (World Bank) www.worldbank.org Ramsar Convention www.ramsar.org