226 Hydrocomplexity: New Tools for Solving Wicked Water Problems Kovacs Colloquium, July 2010 (IAHS Publ. 338, 2010) Maximising hydro-power generation within a multi-user water supply system L. BAPELA1, B. MWAKA1, R. CAI1 & H. G. MARÉ2 1 Department of Water Affairs and Forestry, South Africa
[email protected] 2 WRP Consulting Engineers (Pty) Ltd, South Africa INTRODUCTION In order to optimise the generation of hydro-power from Gariep and Vanderkloof dams, and to supply the other water users at the required risk levels, a system utilisation agreement was formed between the Department of Water Affairs (DWA) of the Republic of South Africa (RSA) and Eskom (the national energy supplier within the RSA). As part of the agreement between DWA and Eskom, DWA commissioned the Orange River System Annual Operating Analysis study to ensure that all the users are supplied at the required assurance and to determine the volume of water available for the generation of hydro power on an annual basis. Background Gariep and Vanderkloof dams are the two largest dams in the RSA, located in the Orange River, with gross storages of 5343 million m3 and 3187 million m3, respectively. Several water supply sub-systems, including the well known Lesotho Highlands Water Project (LHWP), are located upstream of Gariep and Vanderkloof dams. These sub-systems, some with large transfers, all have an effect on the water availability in Gariep and Vanderkloof dams, also referred to the as the Orange River Project (ORP). The total 2008 demand imposed on the ORP is in the order of 3200 million m3/year-1 and is just lower than the historic firm yield of 3 349 million m3/year-1.