Water Quality and Algal Assemblages of the Sabie River and Tributaries, Including the Inyaka Dam, in Relation to Land Use Practices Report to the WATER RESEARCH COMMISSION by S BARNARD, TL MORGENTHAL, M STOLZ, A VENTER AND A ERASMUS North-West University WRC Report No. 2755/1/19 ISBN 978-0-6392-0091-0 October 2019 Obtainable from Water Research Commission Private Bag X03 GEZINA, 0031
[email protected] or download from www.wrc.org.za DISCLAIMER This report has been reviewed by the Water Research Commission (WRC) and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the WRC, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. © Water Research Commission ii EXECUTIVE SUMMARY BACKGROUND Aquatic ecosystems across the world are under pressure due to the increasing demand for water. This increase in demand is linked to a growth in urbanization, and industrial and agricultural development. These trends are also visible in South Africa where the river systems are furthermore stressed by the dry climatic conditions. The deterioration of river water quality due to unsustainable anthropogenic activities is currently an important environmental concern worldwide. Deforestation, agricultural activities and urbanization modify land surfaces which can alter runoff volume, generate pollution and can increase algal production. The Sabie River catchment forms part of the bigger Inkomati-Usuthu Water Management Area (IUWMA) under the management of the Inkomati Usuthu Catchment Management Agency (IUCMA) in Mpumalanga Province. It covers about 6 320 square kilometres. The headwaters of the Sabie River and its tributaries such as the Sand River and Marite River arise from the upper Drakensberg escarpment, flowing eastwards into the Lowveld through changing topography, through the Kruger National Park (KNP) into Mozambique where it becomes part of the Incomati Basin.