The role of geodiversity on the groundwater resource potential in the upper Blue Nile River Basin, Ethiopia

Abstract

Groundwater has been the main source of water supply for large cities and towns over the last few decades in the upper Blue Nile River Basin, Ethiopia. However, provision is often unsuccessful because of poor well productivity, difficult drilling conditions, poor well positioning, or sometimes due to poor water quality. The growing pressure of urban population and industrial development is focusing unprecedented attention on the groundwater potential of the basin. The purpose of this work is to spatially characterize the groundwater potential of the upper Blue Nile River Basin with respect to variable recharge and geodiversity. The study shows that from the annual recharge obtained using the base flow separation method, the renewable groundwater potential in the basin was estimated to be in the range of 1.2 and 2 billion m 3 /year. The aquifers in the area are divided into three categories: low to moderate productivity (&3.5 l/s) which includes crystalline basement rocks, acidic lava flows and domes, and very fine alluvial sediments; moderate to high productivity (&5.5 l/s) that includes Mesozoic sedimentary rocks (sandstone, limestone, gypsum, dolomite); and high to very high productivity (&20 l/s) which includes basic lava flows of the Trap series, Quaternary lava flows and alluvial sediments.

Development of a Hydrogeological Conceptual Model for Shallow Aquifers in the Data Scarce Upper Blue Nile Basin

“…Backyard irrigation in the area is comparatively high as compared to many other sites in Ethiopia with potential to increase in the near future, and thus, the area is designated as a growth corridor by the government [16], which is the reason for its selection as the study site. Agriculture in the area is predominantly rainfed and it has been proposed that utilisation of shallow groundwater for small-scale irrigation could provide a second growing season delivering the aforementioned benefits to the local community [21].Within the Lake Tana Basin, the deep Eocene-Miocene flood basalts and the overlying Quaternary basalts are well-described in the literature, in terms of recharge and flow mechanisms, isotope and hydrochemistry, and (less common) aquifer properties; this deeper geology provides the water source for the few public supply boreholes in the area (e.g., [22][23][24]). However, the superficial weathered layer is rarely considered, and this layer is the shallow unconfined aquifer that is utilised by rural communities via manually excavated wells.…”

“…Within the Lake Tana Basin, the deep Eocene-Miocene flood basalts and the overlying Quaternary basalts are well-described in the literature, in terms of recharge and flow mechanisms, isotope and hydrochemistry, and (less common) aquifer properties; this deeper geology provides the water source for the few public supply boreholes in the area (e.g., [22][23][24]). However, the superficial weathered layer is rarely considered, and this layer is the shallow unconfined aquifer that is utilised by rural communities via manually excavated wells.…”

Recharge–Discharge Relations of Groundwater in Volcanic Terrain of Semi-Humid Tropical Highlands of Ethiopia: The Case of Infranz Springs, in the Upper Blue Nile

“…Other high-discharge springs are emerging at springs at the foot of the Choke shield volcanic mountain (outside the study area), such as the Bure Baguna, Andasa, and Jiga springs. Choke Mountain is a regional shield volcano, which is characterized by large networks of deep-running tectonic discontinuities [14]. The springs are recharged through these discontinuities, from outside their local catchment [14].…”

“…Choke Mountain is a regional shield volcano, which is characterized by large networks of deep-running tectonic discontinuities [14]. The springs are recharged through these discontinuities, from outside their local catchment [14]. The Areke, Lomi, Tikur Wuha, and Infranz twin springs are situated to the north of Choke Mountain, and these springs were inferred to receive recharge in a comparable way also [14].…”

Groundwater as a Viable Resource Under Climate Change in the Nile Basin: A Rapid Hydrogeological Assessment

“…High summer rainfall in the Ethiopian part of the Nile Basin generates large stream discharge due to rugged and steep topography that facilitates runoff formation and hence, limited recharge into the volcanic and fractured basement transboundary aquifer system between Sudan and Ethiopia (Abiye, 2010). The main aquifers in the Blue Nile Basin are mainly compart mentalized as a result of Plio-Quaternary faults and dikes that intersect different lithologies in the basin, with the optimum yield of boreholes that varies between 3.5 and 20 L/s where high discharge occurs in the low lying aquifers (Abiye and Kebede, 2011). Even if rainfall and recharge are high on the plateau, the high groundwater storage areas are located in the lowland areas due to rapid circulation of groundwater from recharge zones.…”