WMA12: Mzimvubu to Keiskamma Water Management Area
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DEPARTMENT OF WATER AFFAIRS AND FORESTRY DIRECTORATE OF OPTIONS ANALYSIS LUKANJI REGIONAL WATER SUPPLY FEASIBILITY STUDY APPENDIX 2 ECOLOGICAL RESERVE (QUANTITY) ON THE KEI RIVER PREPARED BY IWR Source-to-Sea P O Box 122 Persequor Park 0020 Tel : 012 - 349 2991 Fax : 012 - 349 2991 e-mail : [email protected] FINAL January 2006 Title : Appendix 2 : Ecological Reserve (Quantity) on the Kei River Authors : S Koekemoer and D Louw Project Name : Lukanji Regional Water Supply Feasibility Study DWAF Report No. : P WMA 12/S00/3108 Ninham Shand Report No. : 10676/3842 Status of Report : Final First Issue : February 2004 Final Issue : January 2006 Approved for the Study Team : …………………………………… M J SHAND Ninham Shand (Pty) Ltd DEPARTMENT OF WATER AFFAIRS AND FORESTRY Directorate : Options Analysis Approved for the Department of Water Affairs and Forestry by : A D BROWN Chief Engineer : Options Analysis (South) (Project Manager) L S MABUDA Director ACKNOWLEDGEMENTS The following specialist contributed to and participated in the Kei Reserve Specialist meeting: Drew Birkhead Hydraulics Streamflow Solutions Anton Bok Fish Anton Bok & Associates Denis Hughes Hydrology IWR Rhodes Nigel Kemper Riparian Vegetation Integrated Environmental Assessments Neels Kleynhans Fish DWAF, RQS Delana Louw Process specialist IWR Source-to-Sea Jay O'Keeffe Facilitator IWR Rhodes Nico Rossouw Water quality Ninham Shand Consulting Services Christa Thirion Invertebrates DWAF, RQS Mandy Uys Invertebrates Laughing Waters Roy Wadeson Geomorphology Private DWAF (Resource Directed Measures Office) and Ninham Shand for their participation and contribution: Rod Blackhurst Ninham Shand Alan Brown DWAF Thokozani Mbele RDM Office Retha Stassen RDM Office Program design and presentation of graphs and integration of specialist documents: Delana Louw IWR Source-to-Sea Shael Koekemoer IWR Source-to-Sea Report Editing Shael Koekemoer and Delana Louw IWR Source-to-Sea IWR Source-to-Sea Lukhanji Regional Water Supply Study Report no July 2005 Ecological Reserve (quantity) on the Kei River Page i The following specialist contributed to and participated in the Kei Reserve Specialist Report: Chapter 1: Introduction and Background Delana Louw Chapter 2: Approach: Determination of stress indices Delana Louw Neels Kleynhans Chapter 3: Approach: Ecological classification Delana Louw Neels Kleynhans Chapter 4: Approach: Determination of IFR scenarios Delana Louw Neels Kleynhans Chapter 5 – 16 Shael Koekemoer Chapter 17: Delana Louw Neels Kleynhans Christa Thirion IWR Source-to-Sea Lukhanji Regional Water Supply Study Report no July 2005 Ecological Reserve (quantity) on the Kei River Page ii EXECUTIVE SUMMARY BACKGROUND The National Water Act (No. 36 of 1998) is based on the central guiding principles of sustainability and equity. Sustainability of resource use is to be ensured by the implementation of resource protection measures, including the application of the Ecological Reserve (the quality, quantity and reliability of water required to maintain the ecological functioning of aquatic ecosystems). IWR Source-to-Sea was requested by Ninham Shand to undertake an Ecological Reserve Determination for the Quantity component on the Kei System at an Intermediate level for the major section of the study area using the Intermediate Ecological Reserve Methodology (IERM). This report documents the proceedings of a specialist meeting during which the Ecological Water Requirement (quantity) Scenarios were determined. STUDY AREA AND IFR SITES The study area for the IERM included the Black Kei upstream of its confluence with the White Kei and downstream of its confluence with the Klaas Smits River, the White Kei River below Xonxa dam, Oxkraal River below the Oxkraal Dam, Klipplaat River below Waterdown Dam. • IFR 1: Klipplaat River below Waterdown Dam. • IFR 2: On the upper Black Kei River downstream of the Klaas Smits River confluence. • IFR 3: On the lower Black Kei River above the White River confluence. • IFR 4: On the White Kei River below the Xonxa Dam and below the Indwe River confluence. ECOLOGICAL CLASSIFICATION The process according to the current RDM specifications was applied. This process is under review. Very broadly the process consists of an assessment of reference conditions, the Present Ecological State (PES) (i.e. how far has the system moved from reference conditions and why), the Ecological Importance and Sensitivity (EIS) and the range of ECs which will then be addressed is specified. The results are provided below: IFR sites PES EIS REC Alternative scenario Alternative scenario IFR 1 C Moderate C B/C D IFR 2 D Moderate D - C IFR 3 C/D Moderate C/D B/C D IFR 4 C Moderate C/D B/C D IFR SCENARIO RECOMMENDATIONS IFRs represent the flow component of the Ecological Reserve. The method used during this study is a combination of the FS-R method (low flows), the Building Block Methodology and DRIFT (high flows). The FS-R indicates where natural stress has been decreased to the detriment of the natural ecosystem balance under present conditions. The results are summarised in the following table as a % of the MAR. IWR Source-to-Sea Lukhanji Regional Water Supply Study Report no July 2005 Ecological Reserve (quantity) on the Kei River Page iii IFR as % IFR as % Alternative IFR as % IFR Alternative REC of present of present scenario of present site scenario (up) MAR MAR (down) MAR IFR 1 C 24.8 B/C 29.2 D 17.5 IFR 2 D 9.2 C 14.7 - - IFR 3 C/D 11.2 B/C 20.1 D 7.8 IFR 4 C/D 20.7 B/C 30.4 D 16 The confidence specialists have in their data and their recommendations in general varied from medium-low to medium-high. ECOLOGICAL CONSEQUENCES OF OPERATIONAL FLOW SCENARIOS The objective of this phase of the study was to determine the ecological (or more correctly biophysical) consequences of different flow scenarios at each IFR site. During this assessment, consideration is given on whether the IFRs are available, can be managed or supplied as well as the impact on existing users. Various alterations of the IFR to achieve the same objective or EC are considered with the objective to recommend an optimised scenario (if available). Flow scenarios were developed and tested whether the REC is met (see table below). Y = yes; N = no PES REC SC1 SC2 SC3 SC4 SC5 NO IFR IFR 1 C C Y Y Y Y Y N (?) IFR 2 D D Y Y Y Y Y N IFR 3 C/D C/D Y Y Y Y Y (?) N (?) IFR 4 C/D C/D N Y Y Y(?) N N Number of IFR sites where 3Y 4Y 4Y 4Y(?) 3Y 4N ecological objectives are 1N 1N achieved Scenario 4, 5 and No IFR are the only practical scenarios to assess as they consider existing constraints. Of these scenarios, Scenario 4 has the least ecological impact as it meets the ecological objectives at all the IFR sites. The 'No IFR' scenario is not an acceptable scenario from an ecological point of view as it does not meet the REC at any site. The Scenario 5 has the least impact on yield but cannot meet the REC at IFR 4 on the White Kei. For the Black Kei and Klipplaat River, Scenario 5 would be acceptable. A decision must be made comparing the socio-economic value and importance of the White Kei system compared to the Ecological Importance. Other factors such as the present use of Goods and Services as part of Resource Economics and the potential impact on this if the river is allowed to degrade, as well as the confidence in the IFR 4 assessment and the ecological consequences assessments should be considered to aid in the decision IWR Source-to-Sea Lukhanji Regional Water Supply Study Report no July 2005 Ecological Reserve (quantity) on the Kei River Page iv LUKANJI REGIONAL WATER SUPPLY FEASIBILITY STUDY KEI RIVER WATER QUALITY RESERVE DETERMIANTION CONTENTS 1 INTRODUCTION AND BACKGROUND ............................................................................ 1-1 1.1 Background.................................................................................................................... 1-1 1.2 Study area ......................................................................................................................1-1 1.3 Purpose of this report..................................................................................................... 1-1 1.4 Outline of the report ...................................................................................................... 1-2 2 APPROACH: DETERMINATION OF STRESS INDICES (CHAPTER 5)....................... 2-1 2.1 Introduction ...................................................................................................................2-1 2.2 Fish (CJ Kleynhans) (Chapter 5.1)................................................................................ 2-1 2.2.1 Hydraulics input (A L Birkhead) ...................................................................... 2-5 2.3 Invertebrates (M Uys & C Thirion) (Chapter 5.2) ........................................................ 2-6 2.4 Riparian Vegetation (N Kemper) .................................................................................. 2-7 2.5 Natural and present day stress profiles.......................................................................... 2-8 3 APPROACH: ECOLOGICAL CLASSIFICATION (CHAPTER 6)................................... 3-1 3.1 General approach........................................................................................................... 3-1 3.2 Reference conditions (Chapter 6.1)............................................................................... 3-6 3.3 Present Ecologial State (PES) (Chapter 6.2)................................................................