Environmental Flow Assessment
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Environmental Impact Assessment Project Number: 49055-003 Document Stage: Draft November 2018 PAK: Hydropower Development Investment Program, Tranche 1 Environmental Flow Assessment Prepared by Hagler Bailly Pakistan for the Pakhtunkhwa Energy Development Organization and the Asian Development Bank. This environmental impact assessment is a document of the borrower. The views expressed herein do not necessarily represent those of ADB's Board of Directors, Management, or staff, and may be preliminary in nature. In preparing any country program or strategy, financing any project, or by making any designation of or reference to a particular territory or geographic area in this document, the Asian Development Bank does not intend to make any judgments as to the legal or other status of any territory or area. Balakot Hydropower Project Environmental Flow Assessment Draft Report HBP Ref.: D8EF3BPK November 23, 2018 Environmental Flow Assessment for Balakot Hydropower Project Contents 1. Introduction ...................................................................................... 1-1 1.1 Balakot Hydropower Project .................................................................... 1-1 1.2 Other Hydropower Developments on the Kunhar River ........................ 1-4 1.3 Objectives of the EFlow assessment ...................................................... 1-5 1.4 Organization of this Report ..................................................................... 1-7 1.5 Acknowledgements .................................................................................. 1-7 2. EFlow Study Area and Assessment Sites ..................................... 2-1 2.1 EFlow Study Area ..................................................................................... 2-1 2.2 Catchment Delineation ............................................................................. 2-1 2.3 EFlow Sites ............................................................................................... 2-2 3. Assessment Scenarios ................................................................... 3-1 3.1 Flow Scenarios ......................................................................................... 3-1 3.2 Management Scenarios............................................................................ 3-1 3.3 Combined Scenarios for Eflow Assessment .......................................... 3-5 3.3.1 Baseline Scenarios ........................................................................... 3-5 3.3.2 Impact Assessment Scenarios ......................................................... 3-5 4. DRIFT Indicators and Inputs .......................................................... 4-1 4.1 List of Indicators ...................................................................................... 4-1 4.2 Hydrology Data ......................................................................................... 4-5 4.3 Hydraulic Data .......................................................................................... 4-6 4.4 Response Curves ..................................................................................... 4-6 4.4.1 Scoring Methodology ........................................................................ 4-6 4.4.2 Uncertainty ....................................................................................... 4-7 4.5 Barrier Effects ........................................................................................... 4-8 4.5.1 Sediment Trapping and Flushing ...................................................... 4-9 4.5.2 Barrier to Fish Movement ................................................................. 4-9 4.6 Values for Non-Flow Related Indicators ............................................... 4-12 5. Biophysical Outputs........................................................................ 5-1 5.1 Reporting Methodology ........................................................................... 5-1 5.2 Biophysical Results ................................................................................. 5-1 Hagler Bailly Pakistan Contents D8EF3BPK: 11/23/18 ii Environmental Flow Assessment for Balakot Hydropower Project 6. Analysis of Results ......................................................................... 6-1 6.1 Impact of Various Management and Operational Alternatives on Fish Abundance ....................................................................................... 6-1 6.1.1 Impact of Increasing Protection Levels ............................................. 6-1 6.1.2 Impact of Increasing EFlow .............................................................. 6-2 6.1.3 Impact of Baseload vs Peaking Generation ...................................... 6-3 6.2 Net Gain Calculations .............................................................................. 6-3 6.3 Impact to Power Generation .................................................................... 6-7 7. Conclusions ..................................................................................... 7-1 Appendices Appendix A: Overview of DRIFT Model for Environmental Flow Assessment Appendix B: Reservoir Operations Modelling Appendix C: Hydraulics Appendix D: Response Curve Library Hagler Bailly Pakistan Contents D8EF3BPK: 11/23/18 iii Environmental Flow Assessment for Balakot Hydropower Project Exhibits Exhibit 1.1: Project Location .................................................................................... 1-2 Exhibit 1.2: Project Layout ....................................................................................... 1-3 Exhibit 1.3: HPPs on the Kunhar River .................................................................... 1-6 Exhibit 2.1: Catchment Delineation for BHEP EF Study Area*................................. 2-1 Exhibit 2.2: Selected EFlow Sites for BAHPP EF Assessment ................................ 2-2 Exhibit 2.3: EFlow Study Area and EF Sites ............................................................ 2-3 Exhibit 3.1: BAHPP Dam Operational Scenarios and IDs ........................................ 3-1 Exhibit 3.2: Pressure Levels over Time as Incorporated into DRIFT ........................ 3-3 Exhibit 3.3: Area of Management for BAHPP BAP .................................................. 3-4 Exhibit 3.4: Baseline Scenarios ............................................................................... 3-5 Exhibit 3.5: Impact Assessment Scenarios and IDs ................................................. 3-5 Exhibit 4.1: Discipline indicators used in the DRIFT DSS ........................................ 4-1 Exhibit 4.2: DRIFT Severity Ratings and their Associated Abundance Change ....... 4-6 Exhibit 4.3: DRIFT Uncertainty Margins .................................................................. 4-8 Exhibit 4.4: Alwan Snow Trout Migration Pattern ................................................... 4-11 Exhibit 4.5: Predicted End Values of Selected Indicators under the Management Options ......................................................................... 4-13 Exhibit 4.6: Comments on Trends in Indicators Over time ..................................... 4-15 Exhibit 5.1: Mean Annual Runoff EF Site 2 (Downstream of Dam) .......................... 5-1 Exhibit 5.2: Hydrology Indicators EF Site 1 and 2 .................................................... 5-2 Exhibit 5.3: Hydrology Indicators EF Site 3 and 4 .................................................... 5-4 Exhibit 5.4: Biophysical Results for EF Site 1 (Upstream of Dam) ........................... 5-7 Exhibit 5.5: Biophysical Results for EF Site 2 (Downstream of Dam)....................... 5-8 Exhibit 5.6: Biophysical Results for EF Site 3 (Downstream of Tailrace) ................. 5-9 Exhibit 5.7: Biophysical Results for EF Site 4 (Downstream of Balakot) ................ 5-11 Exhibit 6.1: Impact of Variation in Protection on Fish Population, Downstream 3 of Tailrace (Baseload Generation with EFlow of 3.5 m /s) .................... 6-2 Hagler Bailly Pakistan Exhibits D8EF3BPK: 11/23/18 iv Environmental Flow Assessment for Balakot Hydropower Project Exhibit 6.2: Impact of Variation in Flow on Fish Population, Downstream of Dam with High Protection ..................................................................... 6-3 Exhibit 6.3: Impact of Baseload vs. Peaking Operation on Fish Population, Downstream of Tailrace ........................................................................ 6-3 Exhibit 6.4: Current Distribution of Fish between River and Tributaries ................... 6-4 Exhibit 6.5: Summary of Net Gain Calculations for Selected Scenarios ................... 6-4 Exhibit 6.6: Details of Net Gain Calculations ........................................................... 6-6 Exhibit 6.7: Power Loss Under EFlow Scenarios ..................................................... 6-7 Hagler Bailly Pakistan Exhibits D8EF3BPK: 11/23/18 v Environmental Flow Assessment for Balakot Hydropower Project 1. Introduction The Pakhtunkhwa Energy Development Organization (PEDO) intends to construct a 310 megawatt (MW) run-of-river hydropower plant (the “Project” or “BAHPP”) on the River Kunhar. The Project and related infrastructure will be located in Mansehra District of Khyber Pakhtunkhwa (KP), Pakistan. The Asian Development Bank (ADB) is evaluating the Project for financing under its Hydropower Investment Development Program. 1.1 Balakot Hydropower Project The Project site is located on the Kunhar River about 18.6 km upstream of the town