Brief introduction to DRIFT. Downstream Response to Imposed Flow Transformations

Transcription

1 Brief introduction to DRIFT Downstream Response to Imposed Flow Transformations

2 Development began in 1998 Examples of applications: History : Lesotho Highlands Water Project : 19 river system in South Africa 2006: Zambezi Delta (Mozambique), funded by the International Crane Foundation and the Carr Foundation 2007: Mzingwane River (Zimbabwe), funded by IUCN 2007: Phuthiatsana River (Lesotho), funded by Lesotho Department of Water Affairs : Pangani Basin (Tanzania), funded by IUCN and the Tanzanian government : Nile River (Sudan), funded by the Sudanese Dams Implementation Unit : Okavango Basin (Angola, Namibia, Botswana), funded by GEF/UNDP : Lower Zambezi River (Mozambique), funded by Riversdale Mining : Kunene River (Namibia and Angola), funded by the Angolan and Namibian Governments : Neelum-Jhelum River (Pakistan), funded by the Government of Pakistan 2011: Kagera River (Nile Basin), funded by the Nile Basin Initiative 2011: Huaura River (Peru), funded by SN Power : Poonch River (Pakistan), funded by Mira Power 2014: middle Zambezi River (Zambia and Zimbabwe), funded by the Zambezi River Authority 2015: Lower Mekong River (Laos, Thailand, Cambodia, Vietnam), funded by the Mekong River Commission 2016: Elephant Marshes, Shire River (Malawi), funded by Malawi Ministry of Water Development and Irrigation. Recognised as a good practice methodology by the World Bank, ADB, IFC, IUCN, OKACOM, and the South African, Tanzanian and Pakistan governments

3 Location of applications Nile River Kagera River Poonch River Trishuli River N-J Basin Mekong River Huaura River Kouilou-Niari Rver Cuanza River Okavango River Cunene River Orange/Senqu Basin Olifants-Doorn Basin Berg Basin Pangani River Shire River Zambezi River Pungwe River Pongola River c. 50 projects in total

4 The Hague: Permanent Court of Arbitration (December 2013) For a project of the magnitude of the Kishenganga Hydropower Project, the Court is of the view that an in-depth assessment of the type that Pakistan has attempted for these proceedings is an appropriate tool for estimating potential changes in the downstream environment. Verbatim: In the matter of the Indus Waters Kishenganga arbitration The International Court of Arbitration constituted in accordance with the Indus Waters Treaty 1960 December 2013

5 Generic steps in DRIFT Step 1: Select scenarios Step 2: Select focus areas Step 4: Indicators Baseline Step 3: Model hydrology, hydraulics Step 5: Assign Baseline Status and trends Step 6: Knowledge capture Set up DRIFT all sites Create response curves Step 7: Calibration Step 8: Analysis Run DRIFT for all scenarios and generate prediction of change Scenarios

6 Step 1: Scenario selection Scenarios are a means of exploring possible pathways into the future Describe a range of potential development of the river (design, location and operation of infrastructure/abstractions) Dedicate process for scenario selection Informs site and indicator selection

7 The sites are the focus for the DRIFT predictions of ecosystem change Step 2: Site selection

8 Step 3: External modelling Time-series of simulations for baseline and each scenario, at each site: Hydrology Hydraulics estimated sediments Imported into DRIFT

9 Step 4: Status and Trends Assessment Status and Trends: describe the ecological status of the rivers at the time of the study; describe the past ecological status of the rivers, and possibly; describe the future ecological status rivers with and without the water-resource developments included in the scenarios Status of the rivers at the time of the study is most frequently used as the baseline from which to describe change Relative change is predicted no absolutes

10 Step 5: Indicator selection DRIFT indicators are inputs to the DRIFT model Each indicator must have a describable relationship to the flow or sediment regime Indicators describe: the flow regime of the river, e.g., duration of the dry season ecosystem attributes; e.g.; abundance of white fish river-linked social attributes, e.g., riverbank gardens DRIFT will predict how each indicator will change from baseline

11 Step 6: Mapping of indicator links Map links between driving and responding indicators

12 Severity rating indicating change in abundance Step 7: Knowledge Capture Each mapped link requires a response curve Construct the response curves Dry season duration (days)

13 Response Curves Means of capturing information and understanding: from in-depth scientific data, international knowledge, national knowledge or local wisdom. created by EF specialists with a working knowledge of the river ecosystem and its users graphic and explicit with supporting explanations allow qualitative as well as quantitative knowledge to be captured; amenable to adjustment as knowledge increases.

14 Severity rating Severity change Equivalent Loss or gain 5 Very large 501- (to pest proportions) 4 Large Moderate Low Negligible None No change -1 Negligible Low Moderate Large Very large

15 Severity of change relative to PD Median Example: Response Curve Response of one ecosystem indicator (Fish Guild A) to minimum dryseason flows in a year Fish Guild A Specialists specialists construct draw curve curve Dry Season Minum um Discharge

16 t/day > median c. 45% increase t/day > median c. 25% increase t/day < median c. 20% decrease The higher the wet season average sediment load, the more river energy that is expended carrying sediment, and the lower likelihood of erosion.

17 6 weeks earlier median c. 15% increase 2 weeks later median No change 10 weeks later median c. 15% decrease The onset of the dry season represents a time rhithron species are able to migrate to shallower areas with suitable substrate for spawning, earlier onset allows the fish greater time to migrate but late onset can distrupt spawning migration and maturation. Also if dry season starts earlier, it beneficial as fish can mature in less stressful conditions prior to spawning.

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19 Step 7: Calibration Refine Response Curves using the historical flow record, so that DRIFT outputs reflect current understanding and monitoring data Use a series of calibration sequences to further refine the response curves, e.g.: Sequence of wet years Sequence of dry years Sequence of several dry years, followed by several wet years, repeated Calibration increasingly stabilises the model

20 Step 8: Analysis For each site under each scenario: Enter input time-series into DRIFT (hydrology, hydraulics, sediments) Define other concerns for scenarios (barriers, management, etc.) Calculate the values for all input indicators Run DRIFT to pass input indicators through the ecosystem response curves Generate predictions of change for each indicator and overall ecosystem condition Post-process results into report format

21 Severity of change relative to PD Median Modelled time series Each responding indicator Fish Guild A Transformed into time series of driving indicators Dry Season Minumum Discharge Scenario: Dry season minimum discharge for each year

22 External modelled time series Each responding indicator Transformed into time series of driving indicators DRIFT prediction of change for each year 30 years of record = 30 values Curves combined using multi-criteria decision analysis procedures

23 Response curves for each linked indicator Indicators and Linked Indicators Modelled sediment time-series Modelled hydrology time-series Modelled water quality time-series Geomorphology Linked indicators for Indicator A Temperature Depth Vegetation Macroinvertebrates Hydraulics Velocity Sandy banks Marginal vegetation Macroinvert spp. Time-series of change in indicator A

24 Examples of DRIFT outputs

25 Time-series of change for one indicator at one site under fifteen scenarios

26 Fish Macroinverteb Riverine vegetation Water quality Geomorphology KMax K3.94 K10 K20 K40 K60 K100 K7E3 K9E1 Change in indicator abundance under each scenario, colour-coded to show severity of change Ecosystem Indicators Secondary channels, backwater Cobble and boulder bars Sand and gravel bars Bed sediment size Active channel width Depth of pools Dilution of pollution loads Temperature Algae Marginal vegetation Natural terrace veg Simuliidae Other flies & midges EPT abundance Brown Trout Tibetan Snow Trout Alwan Snow Trout High Altitude Loach K. Hillstream Loach Himalayan Cat Fish

27 Change in ecosystem condition (integrity) at a site under scenarios Overall integrity score with Min and Max (LOC) PD MA MD HW K5N9 K10N9 K20N9 K40N9 K60N9 K80N9 Scenarios Integrity A to B B to C C to D D to E E to F K100N9 KH5E5N9 KH7E3N9 KH9E1N9 KMDN9 KHWN9 K394N9 KMD3N9 KMD4N9 A B C D E

28 Snapshot of basin-wide ecosystem condition under different scenarios Present Day Low Medium High A B C D E Not assessed