Environmental Impacts of Earth Dam Failures and Spillway Malfunctions

This study was carried out in selected districts of Mashonaland, East and Central provinces of Zimbabwe in 2011 to determine the environmental impacts of earth dam failures and spillway malfunctions with regards to soil erosion. A total of 14 earth dams were investigated. Eight dams contributed to soil erosion whilst six did not. Of the eight dams, half of them had breached. The remainder had not breached but had eroded the spillway channel. Only one dam breached without causing soil erosion. The properly constructed dams had contributions to degradation due to erosion ranging from 0.1% to 2.8%. Dam code 3 had the highest contribution to degradation due to soil erosion of 42%. The paper concluded that there is critical loss of soil when a dam fails or when a spillway malfunctions. Concerning spillways, it was shown that when the spillway channel is not properly designed, a lot of soil lose occurs within its channel