The Positive Effect of Micro-Dams for Groundwater Enhancement: a Case Study around Tsinkanet and Rubafeleg Area, Tigray, Northern Ethiopia

Abstract

The government of Tigray Regional State, Northern Ethiopia has been conducting a massive construction of micro-dams (small reservoirs) in order to decrease the rainfall dependency and alleviate food insecurity in drought prone areas of the region. Tsenkanet and Rubafeleg reservoirs are examples of this endeavor. The purpose of this investigation is to evaluate the role of these micro-dams in enhancing the surrounding groundwater by artificial recharge. In this study the physical characteristics of the reservoir are discussed including the groundwater surface water relationship with respect to water level elevation and also hydro-chemical composition. Six water samples have been analyzed. Samples are taken after rinsing the plastic bottles with distilled water and the sample to be taken. One surface water sample from each reservoir and one groundwater samples from each well next to each reservoir has been collected. Moreover, one sample from spring and one from river has been analyzed. The chemical composition of the reservoir water and the surrounding groundwater seem to suggest a similar origin and to be resulting from similar hydro-chemical processes. The chemical composition of all samples is found to be of the CaHCO3 type, which could be explained as resulting from precipitation water in which the mineral calcite has been dissolved. Both the topographic evidence and the water level monitoring data has confirmed the feeding of the reservoir to the near by shallow groundwater system. Quantifying the amount of groundwater accretion by the use of modeling and water balance method is recommended.

Keywords: Groundwater, Surface water, Topography, Water Level, Type, Hardness, Class.