VOLUME 5 TBIA/CIA REPORT 115002924 May 10 , 2019 Rev 0 Only LUANG PRABANGPNPCA POWER COMPANY LIMITED Luang Prabang HPP Cumulative and Transboundary Impact Assessment ReportFor – Volume 5 Only PNPCA For VOLUME 5 CIA/TBIA REPORT 1150002924 May 10, 2019 Rev 0 Only LUANG PRABANGPNPCA POWER COMPANY LIMITED Luang Prabang HPP Cumulative and Transboundary Impact Assessment ForReport – Volume 5 Only PNPCA For Contact Pöyry Energy Ltd. (Thailand) Vanit II Bldg, 22nd Floor, Room#2202 - 2204 1126/2 New Petchburi Road Makkasan, Rajchthewi TH-10400 BANGKOK Thailand Tel. +66 2 650 3171-2 Robert Braunshofer, Business Manager Mobile: +66 92 264 0734 [email protected] Only PNPCA For Only PNPCA For “This report has been prepared by Pöyry Energy Ltd. (“Consultant”) for Luang Prabang Power Company Limited (“Client”, “LPCL”) pursuant to the Contract signed between them (“Agreement”). This report is based in part on information not within Pöyry’s control. While the information provided in this report is believed to be accurate and reliable under the conditions and subject to the qualifications set forth herein Pöyry does not, without prejudice to Pöyry’s obligations towards the Client under the Agreement, make any representations or warranties, expressed or implied, as to the accuracy or completenessOnly of such information. Use of this report and any of the estimates contained herein by anyone else than the Client (“Third Party User”) shall therefore be at the Third Party User’s sole risk. Any use by a Third Party User shall constitute a release and agreement by the Third Party User to defend and indemnify Pöyry from and against any liability of Pöyry, whatsoever in type or nature, in connection with such use, whether liability is asserted to arise in contract, negligence, strict liability or other theory of law. All information contained in this report is of confidential nature and may be used and disclosed by the Client solely in accordance with the terms and conditions set forth in the Agreement.” PNPCA All rights are reserved. This document or any part thereof may not be copied or reproduced without permission in writing from Pöyry Energy Ltd For Only PNPCA For STRUCTURE OF THE FEASIBILITY STUDY VOLUME 1: EXECUTIVE SUMMARY VOLUME 2: MAIN REPORT VOLUME 3: DRAWINGS VOLUME 4: ENVIRONMENTAL AND SOCIAL IMPACT ASSESSMENT VOLUME 5: TRANSBOUNDARY ENVIRONMENTAL IMPACT ASSESSMENT AND CUMULATIVE IMPACT ASSESSMENT VOLUME 6: ANNEXES Only PNPCA For Only PNPCA For Luang Prabang HPP 115002924 Cumulative and Transboundary Impact Assessment Report Table of Contents EXECUTIVE SUMMARY ................................................................................................................... I 1 INTRODUCTION .................................................................................................................. 1 1.1 Purpose of the CIA and TBIA Report ...................................................................................... 2 1.2 Significance of Cumulative and Transboundary Impacts ........................................................ 2 1.3 Relations to the Projects Specific Impact Studies .................................................................... 2 2 THE PROJECT ...................................................................................................................... 3 3 LEGAL AND ADMINISTRATIVE FRAMEWORK ........................................................ 5 4 CUMULATIVE AND TRANSBOUNDARY IMPACTS ................................................... 6 4.1 Methodology and Approach ..................................................................................................... 6 4.2 Determination of Valued Ecosystem Components (VECs) ..................................................... 6 5 RELEVANT ISSUES ................................................................................................Only............. 8 5.1 Hydropower Development Plan ............................................................................................... 8 5.1.1 Hydropower Development at the Mekong Mainstream ........................................................... 8 5.1.1.1 Lancang Cascade ...................................................................................................................... 8 5.1.1.2 Hydropower Development in Lao PDR ................................................................................... 9 5.1.2 Project Features ...................................................................................................................... 10 5.1.3 Reservoir Operation ............................................................................................................... 11 5.2 Hydrology .............................................................................................................................. 12 5.2.1 Introduction ............................................................................................................................ 12 5.2.2 Overview of Previous Studies ................................................................................................ 12 5.2.3 Catchment .............................................................................................................................. 12 5.2.3.1 Mekong River Basin .............................................................................................................. 12 5.2.3.2 Physiography .......................................................................................................................... 14 5.2.3.3 Macroclimate ......................................................................................................................... 16 5.2.4 Data Collection and Processing ............................................................................................. 16 5.2.4.1 Discharge Data ....................................................................................................................... 16 5.2.4.2 Precipitation ................................PNPCA................................................................ ........................... 18 5.2.5 Evapotranspiration ................................................................................................................. 18 5.2.6 Temperature ........................................................................................................................... 18 5.2.7 Hydro-Meteorological Characteristics ................................................................................... 19 5.2.7.1 Precipitation ........................................................................................................................... 19 5.2.7.2 Temperature & Evapotranspiration ........................................................................................ 19 5.2.8 Inflow Hydrology ................................................................................................................... 20 5.2.8.1 Discharge Time Series ........................................................................................................... 20 5.2.8.2For Water Balance Model ............................................................................................................. 21 5.2.8.3 Simulation Results of Natural Streamflow for the Calibration Period .................................. 23 5.2.8.4 Inflow Time Series LP HPP Site ............................................................................................ 24 5.2.9 Flood Hydrology .................................................................................................................... 25 5.2.9.1 Statistical Analysis ................................................................................................................. 25 5.2.9.2 Probable Maximum Flood ..................................................................................................... 27 5.2.10 Impact of Lancang Cascade ................................................................................................... 31 Copyright © Pöyry Energy Ltd. Only PNPCA For Luang Prabang HPP 115002924 Cumulative and Transboundary Impact Assessment Report 5.2.11 Impacts to the Tonle Sap Great Lake System ........................................................................ 33 5.2.12 Hydrological Impact of the LP HPP - Conclusion ................................................................. 35 5.3 Water Quality ......................................................................................................................... 35 5.4 Sediment Transport ................................................................................................................ 36 5.4.1 General Terms and Definitions .............................................................................................. 36 5.4.2 Findings from Literature Concerning Sediment Transport within the Mekong .................... 37 5.4.3 Trend Analyses ...................................................................................................................... 39 5.4.4 Sediment Concentration ......................................................................................................... 41 5.4.5 Conclusion and Findings Concerning Sediment Transport ................................................... 42 5.5 Fish and Fisheries ................................................................................................................... 45 5.5.1 Importance of Local Fisheries ...............................................................................................