Back to the drawing board: assessing siting guidelines for sand dams in Kenya

Abstract

Sand dams have become popular in many parts of the arid world as a relatively cheap and effective water harvesting technology. Kenya is one of the countries with the highest number of such dams, with semi-arid Kitui County having become a major hub in recent decades. These sand dams are used for water storage in the beds of Kitui’s seasonal rivers. The water is used for households and small-scale economic activities. Generally, sand dams are evaluated as very successful, but this paper shows that such success is not guaranteed. Field research conducted in Kitui County in October 2016 suggests that from 116 sand dams surveyed, about half did not have any water during the time of the assessment. This study assesses how various environmental factors affect sand dams’ ability to supply water for community use during dry periods in Tiva River catchment in Kitui County. Most of the assessed environmental factors did not show consistent patterns to draw inferences on how they affect sand dams’ ability to supply water, with the exception of rainfall amount, water indicating vegetation percentage of clay in a soil and stream orders. More overarching factors like agro-ecological zones and stream order do show a pattern of influence on dams’ performance. These results have global significance due to the widespread use or plans to use of sand dams worldwide. There is a clear need to build a better understanding of sand dams performance to define more reliable sand dams’ site identification criteria.