Water Balance Estimation Using Integrated GIS-Based WetSpass Model in the Birki Watershed, Eastern Tigray, Northern Ethiopia

Abstract

This study aims to estimate long-term average annual and seasonal water balance components for Birki watershed using WetSpass model with the integrated geospatial modeling approach with ten years’ hydro-meteorological and biophysical data of the watershed. Both primary and secondary data were collected using both field survey and disk-based data collection methods. The WetSpass model was used for data analysis purposes. The finding showed that in the summer season the annual groundwater recharge is 24.1 mm year-1 (96.5%), winter season mean groundwater recharge is 0.8 mm year-1 (3.5%) and yearly mean groundwater recharge is 24.9 mm year-1, Surface runoff yearly mean value is 40.6 mm year-1, Soil evaporation yearly mean value is 10.8 mm year-1, Evapotranspiration yearly mean value is 60.8 mm year-1, Intersection loss yearly mean value is 17 mm year-1, and Transpiration loss yearly value is 6.8 mm year-1 in the entire watershed. The mean annual precipitation, which is 573 mm, is contributed to 7.4%, 7.1% and 85.5% recharge to the groundwater, to surface runoff, and evapotranspiration, respectively. Annually 1.1205 million m3 water recharges into the groundwater table as recharge from the precipitation on the entire watershed. The contribution of this study could be used as baseline information for regional water resource experts, policy makers and researchers for further investigation. It can also be concluded that integrated WetSpass and GIS-based models are good indicators for estimating and understanding of water balance components in a given watershed to implement an integrated watershed management plan for sustainable utilization and sustainable development.

Assessment of Water Balance Components by Using Wetspass Model: The Case of Dengego Sub-basin, Eastern Ethiopia

“…Similar results are reported in different watersheds in Ethiopia; 20.8% of precipitation, Upper Bilate Catchment, Southern Ethiopia [31], 7.1% of precipitation, Birki Watershed, Eastern Tigray, Northern Ethiopia [30], 6% of annual precipitation, Werii watershed of the Tekeze River Basin, Ethiopia [14], 7.2% of annual precipitation, Geba basin, Northern Ethiopia [2] and 7% of precipitation, Illala Catchment, Northern Ethiopia [26]. About 51.5% of the surface runoff from the Dengego sub-basin occurred in the summer season, and the remaining 48.5% occurred in the winter season.…”

“…Similar investigations have been carried out in different research locations to estimate average groundwater recharge using the WetSpass model. As a result, an average recharge of 28 mm 5% of annual precipitation [33], 37 mm 6% [26], 24.9 mm 7.4% [30], 30.06 mm 4.2% [14], 116 mm 9.4% [31], and 66 mm 12% [26]. In comparison with these findings, the simulated recharge is consistent and reliable in this semi-arid sub-basin.…”

Groundwater-recharge estimation in Waja-Golesha Sub-basin, Northern Ethiopia: An approach using WetSpass Model

“…In other research areas, similar studies have been undertaken to estimate average groundwater recharge using the WetSpass model. Accordingly, average recharge was found to be 28 mm (5% of annual precipitation) by Esayas and Gebeyehu (2019), 37 mm (6%) by Gidafie et al (2016), 24.90 mm (7.4%); Meresa et al (2019), 30.06 mm (4.2%) by Gebremeskel and Kebede (2017), 116 mm (9.4%) ; Dereje and Nedaw (2019), 66 mm (12%); Haile (2015) and 55 mm (8%) by Gebreruael et al (2018).…”

“…WetSpass is originally developed for conditions in the temperate regions in general and Europe in particular (Gebrerufael et al, 2018). Later the model was applied all over the world under different conditions by modifying its parameters (Fenta et al, 2015;Meresa et al, 2019;Salem et al, 2019). The modified WetSpass model was applied in semi-arid region of Ethiopia to simulate the hydrological water balance of the Upper Bilate Catchment (Dereje and Nedaw, 2019), Birki watershed (Esayas and Gebeyehu, 2019) and Werii watershed (Gebremeskel and Kebede, 2017).…”

Untitled

“…Results of [2], the Geba basin in Northern Ethiopia receives 90.7 percent of the annual precipitation. In the Birki Watershed, Eastern Tigray, Northern Ethiopia, [30] get 85.5 percent of yearly precipitation. [31] simulated 69.8% of annual precipitation in the Upper Bilate Catchment, Southern Ethiopia, and [26] reported 81 percent in the Illala Catchment, Northern Ethiopia.…”