Groundwater management strategies and their implications on irrigated agriculture: the case of Dendron aquifer in Northern Province, South Africa

Abstract

While groundwater is a small component of water resources in South Africa it plays a significant role in irrigation water supply at more localized scales. Aquifer yields are generally low, ranging from less than 1–20 l/s, with most of the aquifers yielding near to the lower end of the scale. The Dendron dolomitic aquifer in the Northern Province of South Africa is a high potential one by local standards, with yields of about 20 l/s. Some boreholes in the area yield much higher than the average 20 l/s. The aquifer has been the sole source of irrigation water for commercial agriculture for more than 20 years. In the eighties groundwater levels were observed to be declining due to over-abstraction. This trend has continued to the present with current water levels averaging about 50–100 m below ground, a drop of more than 50 m in the last 30 years. In 1991 the Department of Water Affairs and Forestry informed farmers that a management strategy would be required to ensure sustainable use of groundwater. Several steps to manage groundwater were taken. Although users are of the opinion that groundwater levels have been increasing, in fact the rate of groundwater level decrease has been increasing. This paper discusses the effect of cropping pattern and irrigation management changes on groundwater levels. The implications of different water management strategies on the sustainability of groundwater-supported agriculture are analysed and recommendations made.