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The demand for fresh water is constantly increasing among all water users. Irrigation in Ethiopia consumes a large amount of water extracted from various sources. Hence, efficient water use and management are currently the major concerns in the country. Thus this paper aims to review the advancements, challenges, and opportunities regarding improving irrigation water use efficiency in Ethiopia. Irrigation in Ethiopia started in the 1950s with traditional irrigation systems. Now modern irrigation, including sprinkler and drip irrigation, is practiced in some parts of the country. The review showed that even though the farmers have practicing irrigation for a long time, still they cannot surpass subsistence farming. Furthermore, improvements in irrigation water use efficiency through proper scheduling and on-farm management are not satisfactory. The paper revealed the challenges that hinder water use efficiency improvement includes crop diseases, socio-economic factors, institution and policy-related issues, limitation in technical and human capacity, lack of agricultural input as well as market and nature-related factors. In the future, increased use of remote sensing techniques, more versatile sensors, simulation, and quantitative models are likely to be seen to improve water use efficiency. In most cases where water is saved as a result of the efficient use of technologies, the spare water ends up being used to expand the irrigation area, which results in an increased income for the household. Hence, to achieve net water savings, water-efficient technologies and practices need to be used in combination with other measures such as incentives for conservation and proper use. Besides, appropriate regulations should be set that limit water allocation and usage. The government and partners should allocate resources for capacity building of farmers regarding irrigation, which in extension will lead to enhancement in WUE.

Optimizing the use of irrigation water is of vital importance in conserving land and water resources as well as maximizing crop yield utilizing available water. Evaluating an irrigation system performance should measure and show the effectiveness of existing irrigation practice, provide remedial measures if necessary, as well as determining the impacts of the factors which affect the performance parameters. This study attempted to evaluate and assess the performance of Quashni irrigation scheme using internal and external performance indicators. Two irrigation seasons in the 2018 (February–May) and 2018/2019 (October–January) were carried out. Primary data, e.g. soil moisture before and after irrigation, discharge measurements, irrigation depth and soil physical properties, were collected. Secondary data, e.g. meteorological data and irrigated area per crops, were also collected. CROPWAT 8.0 computer model was used to calculate the CWR. The conveyance and application efficiency of the scheme was estimated as 71.8% and 51.2% respectively, which led to an overall scheme efficiency of 36.8%. RWS and RIS of the scheme were 1.24 and 1.12, respectively. Irrigation ratio of Quashni irrigation scheme was found to be 0.84, which implies that 16% of the command area could not be provided with irrigation coverage. In general, the evaluation and assessment indicated a low performance of the Quashni irrigation scheme.

Soil water is an important variable in regulating and predicting hydrological process for optimal irrigation. Hydrus-1D was used to simulate soil water dynamics under overhead irrigation in Dengeshita watershed at the plot level. Experiments were carried out from October-February 2017/2018 and from March – June 2018. The treatments were conservation agriculture (CA) and conventional tillage (CT). Irrigation depth, crop phenology, meteorological and soil parameters were determined. Soil parameters were estimated using a K-nearest neighbor approach (KNN) pedotransfer functions for tropical soils and fitted using retention curve optimization program. Sensitivity analysis result showed saturated soil water content (θs), saturated hydraulic conductivity (Ks), and pore size distribution (n) were the most important parameters for the model. The model performance using measured soil water content (SWC) was good with R2 of (0.64–0.77) and errors; RMSE of 0.021–0.063 and ME of 0.0013–0.040. Based on overall evaluation, CA plots had higher average SWC (0.39–0.40 cm3.cm−3) than CT plots (0.36–0.37 cm3.cm−3). The average seasonal actual transpiration was lower for CT (88.76%) than CA (93.46%) plots due to higher evaporation loss (CT = 7.69% and CA = 1.15%); the difference is statistically insignificant. Seasonal deep percolation from CT and CA plots was 0.38% and 3.15% respectively. Therefore, CA was better than CT due to store more water for plants.

Groundwater resource development for various uses is increasing in the Lake Tana basin, as surface water became limited in quantity and quality. Assessment of the groundwater potential (GWP) in the basin is crucial for sustainable use of water resources. This study aims at assessing the GWP in the basin using remote sensing and GIS-based Multi Criteria Decision Analysis (MCDA). Seven factors (lithology, lineaments, drainage density, rainfall, slope, land use/land cover and soils) that affect groundwater distribution were considered. Analytical Hierarchy Process (AHP) approach were used to compute each layer weight. Thematic weighted layers were overlaid in ArcGIS to identify GWP are-as in the basin. The result indicated that, 15% (1765 km2) classified as “very high”, 26.5% (3151 km2) as “high”, 31% (3592 km2) as “medium”, and 27.5% (3224 km2) were classified as “low” GWP zones in the basin. The GWP map was validated using observed borehole and springs data in the basin, and it indicated that 76% of agreement. It was found that GWP was highly sensitive to lithology and rainfall with mean variation index of 2.7% and 2.0%, respectively. High GWP is available at the southern and eastern side of the Lake Tana.