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WATER QUALITY IN THE EFA PROCESS

Jay O’Keeffe,

UNESCO-IHE Institute for Water Education

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WATER QUALITY

• Efficient functioning of river ecosystems requires provision of suitable hydrological regime and water of suitable quality

• 2 aspects of water quality:– How will modified flow regimes affect water

quality? (Incorporate in env. flow recommendations)– What have human activities in the catchment done

to modify the present water quality from natural conditions? (Rehabilitation measures at source)

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WATER QUALITY IN THE BBM METHODOLOGY

• Key questions:– Impact of flow on water quality– Impact of water quality on riverine biota

• Difficulties in assessment of water quality aspects in BBM– Sporadic data availability– Water quality models often not available– Biota response affected by a range of synergistic and

antagonistic effects, rate of concentration change and acclimation

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Water quality variables

• Required:– Physical and chemical water quality conditions

– How these conditions change seasonally / yearly

– Similar data in non-impacted state

• System variables: pH, Temp, O2

• Non-toxic constituents: EC/TDS, TSS, cations (NA, K, Ca, Mg) and anions (SO4, Si, alkalinity)

• Nutrients: total P, total N, NO3, NH4, NH3, NO2, TOC

• Toxic constituents: metals, pesticides, other

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PROTOCOL FOR INCORPORATING WATER QUALITY IN EFA

• Preparation for the workshop

• Identify broad climatic region and ecoregion

• Take note of geomorphological reaches

• Identify significant hydrological features

• Delineate reaches / segments with expected similar water quality

• Establish reference / natural conditions– System variables, nutrients, toxic chemicals

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PROTOCOL FOR INCORPORATING WATER QUALITY IN EFA (cont.)

• Preparation for the workshop (cont.)

• Determine present water quality status– Use water chemistry data– Identify likely threats (sources of contaminants)– List potential point sources of contamination– Identify major land use areas

• Assess the data (completeness of data)

• Prepare the report

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PROTOCOL FOR INCORPORATING WATER QUALITY IN EFA (cont.)

• Roles and responsibilities (at workshop):

• In absence of water quality modeling, make predictions with regard to effect of flow changes on water quality – Based on examination of cross-sections and

hydraulic characteristics

• Advise on flows that should maintain required EMC

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MINIMUM DATA SET

• Seasonal (three-monthly) water chemistry and biomonitoring data over complete annual cycle

• If data not exist: – Make extrapolation from adjacent and comparable

river reach, or – Derive data from reference site

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CONCLUSIONS

• For aquatic ecosystems to function adequately, not only appropriate flows of water, but also of suitable quality are required

• Assessment of water quality requirements for riverine ecosystems entails considerable degree of subjectivity

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