Abstract

In the agricultural areas of Swaziland, the erosion of surficial materials results in the formation of extensive gully systems called "dongas". The presence of dongas strongly increases run-off and, therefore, groundwater recharge to aquifers is considerably reduced. The causes of gully formation are only partially known. This project will study the development of dongas in the Middleyeld of Swaziland. Researchers will determine the effects of gullying on surface and groundwater flow and storage; and make recommendations for basin management and remedial measures to stop or ameliorate the harmful effects.

Post-Project Summary

This project explained and quantified gully morphology based on the nature and distribution of the soil in which they were formed. Erosion potential was determined; and a description of the gully formation process from footpaths and animal trails was given. It was found that gullies were not suitable alternatives to potable groundwater or spring water. The project tested groundwater quality where it was observed and established a small soil testing laboratory at the Maikerns Research Station. Project objectives not achieved included: determining the contribution of gully erosion to the sediment budget of rivers, lakes, and reservoirs; identifying remedial measures for reducing gullying and increasing groundwater recharge and storage; and strengthening groundwater research and basin management capabilities at the Ministry of Natural Resources.

Recipient Institution(s)