Crop water requirement and irrigation scheduling in Lower Kulfo Catchment of southern Ethiopia have not assessed under climate change scenarios, and the allocation of crop land also not optimal that signifcantly challenges to crop productivity.Therefore, this study was conducted to evaluate the effects of climate change on future crop water requirements, and irrigation scheduling, and to allocate cropland optimally. Bias of projected precipitation and temperature were corrected by utilizing Climate Model data with the hydrologic modeling tool (CMhyd). Alongside, crop water requirements and irrigation scheduling were assessed using Crop Water Assessment Tool. After estimating crop water requirement, crop land were allocated optimally using General Algebraic Modeling System programming with non-negativity constraints (scenario 1), and non-negativity constraints based on farmers adaptation (scenario 2). Average reference evapotranspiration from 2030 to 2050 and 2060 to 2080 was increased by 11.9 %, and 16.2 %, respectively compared with the reference period (2010–2022). The total seasonal crop water requirements were 4,529 mm, 4866.7 mm, and 5272.2 mm under 2010 to 2022, 2030 to 2050, and 2060 to 2080 climate change scenarios, respectively. The meean irrigation interval in 2010–2022, 2030 to 2050, and 2060 to 2080 climate change scenarios were 8 days, 7 days, and 5 days, respectively. This irrigation interval was decreased by 14 % (2030–2050), and 34 % (2060–2080) compared with the reference period. In 2030 to 2050 and 2026 to 2080 climate change scenarios, the required irrigation water at the inlet of main canal increased by 6.8 %, and 18 %, respectively. The optimal allocated area for tomato (60.4 %), maize (20.8 %), and watermelon (18.8 %) in scenario 1 with net benefit of 1.47*108 Ethiopian Birr. The allocated areas in scenario 2 were (48 %) for maize, (31.6 %) for tomato, and (20.4 %) for watermelon with 1.34*10⁸ Ethiopian Birr net benefit it was reduced by 19.1 % compared with the net benefit in scenario 1. Fruit crops alone may not suffice for local food needs and to address this, small farmers should grow maize, tomato, and watermelon. This research aids policymakers in encouraging climate-resilient agriculture and improving small-scale farmers' awareness through conducting workshops and training.

Watermelon productivity in the Arba Minch irrigation scheme has been hampered by water scarcity, with only the Lady Bells watermelon variety being cultivated in the area. This challenge can be mitigated by adopting water-saving irrigation techniques and selecting water stress-resistant varieties. Hence, this study aimed to investigate the combined impact of soil mulching and deficit irrigation on the productivity of various watermelon varieties and validate the AquaCrop model. The experiment employed a randomized complete block design with two levels of water application (100 % SMD and 50 % SMD), two mulching practices (non-mulching and mulching), and four watermelon varieties: Lady Bells (V1), Green Pearl (V2), Kaolack (V3), and Koloss (V4). Soil physical properties and crop-related data were used to calibrate the AquaCrop model. Straw mulching, on average, conserved 64.50 mm and 262.75 mm of water under 100 % and 50 % water application levels, respectively. The minimum and maximum land productivity averages were 6.2 tonsha⁻¹ (T13) and 17.6 tonsha⁻¹ (T2), while water productivity ranged from 5.2 kgm⁻³ (T1) to 12.4 kgm⁻³ (T10). Lady Bell watermelon varieties displayed high sensitivity to water stress, with a 1.27 yield response factor under non-soil mulching treatment with 50 % water application. The mean benefit-cost ratio varied from 1.52 (T13) to 2.90 (T10). The average values of RMSE, NSE, and R² for the AquaCrop model were 0.70, 0.65, and 0.80, respectively, indicating the model's acceptability in predicting the effects of mulching and deficit irrigation on watermelon productivity. Overall, the use of straw mulching combined with 50 % deficit irrigation, particularly for Green Pearl varieties, emerged as the most productive watermelon cultivation method in the Arba Minch region when facing limited irrigation water. Future research will focus on assessing the impact of deficit irrigation during various watermelon growth stages.

The lack of soil moisture-based irrigation intervals, poor distribution of irrigation water among users, and the time-based and spatial variability of water supply have been challenges for the productivity of irrigation schemes in the Lower Kulfo catchment, Southern Ethiopia. This study was conducted to develop soil moisture-based irrigation intervals and to evaluate irrigation water delivery and field level irrigation efficiencies. Soil water content, and flow along the canal and in the field were measured directly, and irrigation duty was estimated by using CropWat 8 model. To minimize water stress or excess problems, irrigation needs to be applied when soil water content drops to 35.7 % for onion and pepper, 34.4 %% for watermelon, and 32.5 % for wheat and maize from field capacity. However, irrigation was applied at 36.2 % for onion, 35.4 % for watermelon, 36.4 % for pepper, 36.2 % for maize, and 35 % for wheat in the existing irrigation scheme that increased irrigation amount in the field. The average percentage of soil moisture depletion (p) at time of irrigation was 27.4 %, which was below the recommended value. The average adopted irrigation and design irrigation interval were 4 & 6 days for onion and pepper, 5 & 7 days for watermelon and wheat, and 6 & 7 days for maize, respectively. The mean irrigation adequacy and dependability of the irrigation scheme in the lower Kulfo catchment were 1 & 0 for Arba Minch irrigation scheme, 0.5 & 0.2 for Arba Minch University farmland, 0.4 & 0.25 for private farmland and 0.1 & 0.43 for Kollashara farmland, respectively. The value of irrigation equity was 0.7 in January, 0.6 in February, and 0.8 in March which indicates the highly temporary variation of irrigation adequacy. The mean value of canal conveyance was 82.7 % and the average on-farm irrigation efficiency also was 56.6 %. The average value crop yield in the present study were 0.5ton/ha for wheat, 4.9ton/ha for onion, 6.2ton/ha for pepper, 0.6ton/ha for watermelon, 4.2ton/ha for maize that was very low compared with other control irrigation in the study area. Inadequate soil moisture-based intervals, inequitable water distribution, and variable supply hinder irrigation in the Lower Kulfo catchment; adopting optimized practices and robust management can enhance efficiency, equity, and crop productivity.

Meteorological drought poses a frequent challenge in the Nile River basin, yet its comprehensive evaluation across the basin has been hindered by insufficient recorded rainfall data. Common indices like the standard precipitation index, coefficients of variation, and precipitation concentration index serve as pivotal tools in gauging drought severity. This research aimed to assess the meteorological drought status in the Nile River basin by using the Power Data Access Viewer product rainfall data. Bias correction procedures were implemented to refine the monthly rainfall data for Bahirdar, Markos, Nekemt, and Muger stations, resulting in notable improvements in the coefficient of determination () that were increased from 0.74 to 0.93, 0.72 to 0.89, 0.71 to 0.96, and 0.69 to 0.84, respectively. The average spatial distribution of drought in the Nile basin was classified as extremely wet (3.81%), severely wet (9.01%), moderately wet (7.36%), near normal (9.97%), moderately drought (21.20%), severely drought (17.11%), and extremely drought (31.54%). Approximately 10.33% of the Nile River basin was situated in regions characterized by high rainfall variability, while around 21.17% was located in areas with a notably irregular precipitation concentration index. Overall, this study sheds light on the prevailing meteorological drought patterns in the Nile River basin, emphasizing the significance of understanding and managing these phenomena for the sustainable development of the region.

Irrigated agriculture has been practiced in Ethiopia for several centuries and performance of scheme was poor due to inadequate irrigation water management practices. This study was conducted to evaluate irrigation water management indicators and to suggest possible mitigation measure for Arba Minch irrigation scheme. Primary data such as field and canal flow, soil moisture content, and canal slope were measured on field and soil physical properties were evaluated in the laboratory. Utilizing climate and crop data, the CropWat 8 model was employed to estimate seasonal crop water requirements, while furrow and border irrigation dimensions were designed using SURDEV software. The average field application efficiency (30%), storage efficiency (76%), percolation losses (66%), and overall efficiency (25%). The average relative water and irrigation supply in the scheme were 1.7 and 3.3, respectively. The mean water and land productivity of the wheat, onion, pepper, watermelon, and maize of the Arba Minch irrigation scheme were 0.1 kg/m³ and 0.5 ton/ha, 0.9 kg/m³ and 4.9 ton/ha, 1.5 kg/m³ and 6.2 ton/ha, 0.5 kg/m³ and 0.6 ton/ha, and 0.9 kg/m³ and 4.2 ton/ha, respectively. Watermelon had the highest net returns per hectare ($1,693), followed by onion ($1,829), pepper ($1,221), and wheat ($1,057). In terms of net returns per cubic meter of water, onion led with $0.3, followed by watermelon ($0.2), pepper and wheat with the lowest at $0.1 (top of form). The average value conveyance efficiency, water surface elevation ratio and manning coefficient were 82%, 42%, and 0.06%, respectively. The existing, and corrected length were 843 and 135 m (border irrigation) and 20 and 595 m (furrow irrigation), respectively. In conclusion, the Arba Minch irrigation scheme was very poor performance and low efficiency. To address these issues, farmers and irrigation authorities implement improved irrigation water management practices. Policymakers should promote sustainable water management and explore crops with higher water productivity for overall scheme improvement.

The performance of irrigation schemes in Ethiopia is too low due to a lack of proper system management, water control structure, and strong water user association. This study aimed to assess small‐scale irrigation scheme’s performance and proposed alternative mitigation for improved water management. Direct measurement, laboratory analysis, field observation, and stakeholder interviews were used to collect the primary data. The average conveyance efficiency, water surface elevation ratio, canal delivery capacity, adequacy, and equity of the Wezeqa and Gatto irrigation schemes were 86.37% and 75.4%, 55% and 60.3%, 71% and 55.8%, 0.68 and 0.67, and 0.4 and 0.43, respectively. The mean value of application and storage efficiencies of the Wezeqa and Gatto irrigation schemes were 59.8% and 49.4% and 94.3% and 92.2%, respectively. The effectiveness of infrastructure and weir sediment ratio in the Wezeqa irrigation scheme was 24.4% and 78.5%, respectively, and almost all infrastructures in the Gatto irrigation scheme were not functional. To solve the water shortage for both systems, water‐harvesting technology was proposed having a net volume of harvesting water during the night storage of 13,093.7 and 15,897.6 m³ for Wezeka and Gatto, respectively. Therefore, adopting water‐harvesting technology and establishing strong water user associations are recommended to minimize the water scarcity problem to improve water management and sustainability.