ABSTRACT
Land degradation, low agricultural productivity, and high rainfall variability have been among the major causes of food insecurity in many countries in Africa. One of the areas with such challenges is the Tigray region in northern Ethiopia. In order to ensure food and water security in the region, extensive land restoration and more than 150 small- to medium-scale dams have been implemented over the last three decades. The effects of landscape restoration and surface water harvesting on groundwater recharge were studied and evaluated in five representative watersheds. The study involved (a) evaluation of the types of landscape restoration technologies implemented along a landscape and their hydrogeological settings, (b) monitoring the effects of landscape restoration and dam construction on groundwater (level and quality), and (c) evaluation of the emerging dynamics on the surface and groundwater use and the opportunities for conjunctive use. Results of the study show that different landscape restoration technologies were implemented along the landscape continuum which includes (a) deep trenches, bunds, percolation ponds, and afforestation in the upper parts of the watersheds, (b) gully rehabilitation/treatment works through construction of check-dams (sediment storage and/or water harvesting), gully reshaping as well as the construction of subsurface dams and percolation ponds at middle and lower levels of watersheds, and (c) soil moisture enhancement as well as soil quality improvement at farm levels. Hydrogeologically, the study sites are characterized by shallow unconfined aquifer systems. Groundwater monitoring from 2010 to 2017 revealed that as a result of the landscape restoration and dam constructions, groundwater level, and quality have improved. Integrated landscape restoration and/or dam constructions have resulted in valley floors of the study sites have high potential for shallow groundwater development; an opportunity for the conjunctive use of surface and groundwater. With the shallow unconfined nature of the aquifers, availability of excess runoff, and the emerging increase in water demand, implementation of well-planned groundwater recharge mechanisms could be the next frontier to enhance the availability of water in the region and in other areas with similar conditions.
