Journal of Water and Land Development

Abstract

Small earth dams are most valuable in arid and semi-arid areas where they are used for both domestic and agricultural purposes. These dams however, continue to fail. The causes of such failures are interconnected in the sense that one can trigger the other. Most research into earth dams nevertheless, uses reductionist approaches. Such approaches do not consider the complex interactions between these modes and/or causes. This research used fuzzy cognitive mapping to identify the prominent modes and causes of small earth dam failure in Swaziland and to capture their interactions. A sample of seven earth dam construction experts was purposively selected from five institutions for individual interviews. An individual map was developed from each interview. An aggregated map was thereafter developed by combining seven individual maps. The results indicated that overtopping, piping and sliding were the common modes of earth dam failure. Overtopping was mainly due to siltation whilst animal barrows and tree roots were largely responsible for piping. Sliding was mostly associated construction defects and sudden drawdown. It was concluded that most of the failures were linked to poor management of catchments and that of the dams. It is recommended that future designs and management should increase the level of community participation in order to limit some of the causes associated with land use practices.