The Klein Karoo is situated in the Western Cape, South Africa, and is characterised by low rainfall (100–450 mm yr–1). The Klein Karoo is situated in the primary catchment of the Gouritz River. The mean annual runoff (MAR) for the three major tributaries of the Gouritz River arising in or feeding the Klein Karoo (Touws, Gamka, Olifants) is 540 Mm3 yr–1. Groundwater recharge in the three Klein Karoo catchments is ±257 Mm3 yr–1, but only a portion of this reaches the rivers. The very variable flows result in low 1:50 year yield of 161 Mm3 (30% of MAR). The current demand for water in these catchments is 182 Mm3 yr–1, which exceeds the yield, and demand is projected to increase between 23% and 150% by 2025. Changes in the approach to water management are required, including improving the efficiency of irrigation and land restoration to improve water infiltration and reduce soil erosion. We believe that it is time to change to a water management approach that is designed to anticipate and manage the inherent variability in water resources in the Klein Karoo, thereby placing the region on a path to sustainable development.
The Klein Karoo is an ecologically and economically diverse region of South Africa situated in a broad east–west oriented valley between the relatively well-watered Langeberg-Outeniqua Mountains in the south and the Witteberg-Swartberg Mountains in the north (Fig. 1). It lies within the Gouritz River system whose tributaries extend through the Swartberg Mountains into the Great Karoo. Three biomes meet in the Klein Karoo:1,2 Fynbos, Succulent Karoo and Thicket. Both Fynbos and Succulent Karoo are recognised as global biodiversity hotspots3 with a variety of plant species. The perennial reaches of the Gouritz River system are also important for the conservation of aquatic history of poor management has left much of the Klein Karoo de graded by over-grazing and poor cultivation practices.5 The riverine areas are the worst affected, with only 11% in a near natural state, almost all of which is in source areas which are too steep to cultivate and provide poor forage.5 Extensive land degradation has already altered the hydrology and geohydrology of the Klein Karoo and its aquatic and groundwater-dependent ecosystems.6,7 Vegetation loss and trampling by livestock have altered key processes such as water infiltration, increasing soil erosion and changing river flow regimes.
The Klein Karoo is a semi-arid to arid area and fresh water is a critical constraint to future economic development. Although water is widely recognised as a critical constraint, there is a dearth of information on the state of the water resources in the Klein Karoo. This paper reviews information on the water resources of the Klein Karoo, covering both groundwater and surface water, and highlights some of the key issues, knowledge gaps and future options. Recent overviews include the Water Situation Assessment8 and internal strategic perspective prepared for the Gouritz Water Management Area (WMA),9 which includes the catchments of some of the adjacent coastal river systems.