Irrigation & Drainage Systems Engineering

In Ethiopia small scale irrigation schemes play a vital role in improving the livelihoods of the smallholder farmers’. However, existing small-scale irrigation schemes face various problems related to operation and maintenance, water management and sustainability. This study was conducted to technical performance evaluation of selected Small Scale Irrigation Scheme in Arsi and Western Arsi Zone using irrigation performance indicators. For this two scheme selected were Bubisa from Lemu-Bilbilo district of Arsi zone and Koma Arba from Adaba district of West Arsi Zone. From the study conducted on Bubisa and Koma Arba irrigation scheme using performance indices such as conveyance efficiency (Ec), application efficiency (Ea), on farm water lost (ROR+DPF), storage efficiency (Es), overall efficiency (Eo) and distribution uniformity (DU) and finally identifying problems of the scheme. For these study three farmers’ fields located at head, middle and tail of the two irrigation scheme were selected. From the result, parameters like Ec, Ea, on farm water lost (ROR+DPF), Es, DU and Eo were 67%, 60.27%, 39.73%, 89.59%, 90.50%and 39.77%, respectively for Bubisa irrigation scheme and 78%, 62.25%, 37.25%, 82.33%, 92.78% and 48.70% respectively for Bubisa irrigation scheme. Water Use efficiency (WUE) of Bubisa and Koma Arba scheme were 4.59 and 3.05kg/m3. This means that the yield from one meter cube of irrigation water for Bubisa irrigation scheme was higher than that of Koma Arba irrigation scheme. Sustainability of Irrigation System of the Bubisa and Koma Arba schemes were decreased by 42.7% and 62.5%compared with the planned. Therefore, for the improvement of the irrigation system management and the irrigation practice frequent performance evaluation is very important and solves problems related to operation and maintenance, water management and sustainability.

Beles sugar development project has faced the problems of inadequate and poor uniformity of irrigation water. Thus, the system has failed to meet the crop water demand. Having this, the plantation section irrigators were made the two combined sprinkler heads in one HDPE pipe which is fitted with the main riser like the single sprinkler head. By applying the modified combine sprinkler heads, the cane under water stress has recovered soon relative to the existing sprinkler head. The correlated challenge was the irrigation set hour of the modified combine sprinkler heads was not known and its technical comparative discharge advantage was not determined. Thus, this research work was undertaken to compare the modified two combined sprinkler heads with the normal single sprinkler head and to develop sprinkler set hour under the current operational situation. The parameters evaluated were sprinkler discharge, net depth of water application, gross depth of water application and sprinkler set time. The modified combined sprinkler heads had 43% more discharge than the normal single sprinkler head at the same hydrant pressure of 2.5 bar. The sprinkler set time of the modified combine sprinklers heads at the growth stage of 0-3, 3-6, 6-15 and above 15 months was reduced by 43.5%, 41.2%, 43.5 % and 42.6% respectively compared to the normal single sprinkler head.

within the same design irrigation interval of 15 days and 18 × 18 m sprinkler spacing, the modified combine sprinkler heads at 0-3, 3-6, 6-15 and above 15 growth stage has the sprinkler positions and area coverage of 28, 18, 14 and 9 and 0.907, 0.583, 0.454 and 0.292 ha respectively. The modified combine sprinkler heads is better to cover the area with short time and better amount with relative to the normal single sprinkler head.

The use of agricultural water is the main among all uses of water. Water scarcity is one of the greatest challenges for crop production. In areas with water shortages, water savings in agricultural production is critical and essential. Improved irrigation management strategies and efficient use of irrigation water are the most cost-effective tools to address water conservation issues. Deficit irrigation is a method to increase water use efficiency, decrease water demand, and improve the yield of crops. In deficit irrigation practice, agricultural water productivity (yield per unit of water used) must be improved. Increasing water productivity is a vital element in improved water management for sustainability, health ecosystem functioning, and food security. Maximizing water productivity is better than land productivity for the dry agriculture system.

Improving water productivity is impossible with water stress unless nutrient deficiencies, weeds, and diseases are removed. The general target of this review is to review the effect of deficit irrigation on crop yield and water productivity from the existing literature. The reviewed literature indicated that deficit irrigation approaches improve the yield of maize, onion, tomato and faba bean crops and the efficiency or water productivity of water use.

Furrow irrigation is the dominant surface irrigation method applied worldwide. However, the performance of furrow irrigation is low. Advanced simulation models of surface irrigation have been proved to be effective for the evaluation of system design and management. Batu degaga irrigation scheme is one of the small-scale irrigation schemes in ethiopia. Therefore, this study aimed to evaluate the hydraulic performance of furrow irrigation at batu degaga small scale irrigation scheme using the WinSRFR model. A field experiment was conducted and all measurements used for input parameters were collected from the field. The collected data were processed by Microsoft EXCEL and data analysis was conducted using WinSRFR 4.1.3 software. The statistical indicators of NRMSE, R², RE, d, and λ were used for the comparison between measured and simulated advance time, and recession time. The results of these indicators were 10.5%, 0.98, 0.97, 0.97, and 0.98 for advance time; 2.86%, 0.99, 0.99, 0.9, and 0.995 for recession time which was very good and showed that WinSRFR simulation was acceptable.

Hence, WinSRFR software was employed to evaluate the performance of basic indicators of furrow irrigation such as application efficiency, distribution uniformity, and deep percolation. The study revealed that the average application efficiency, deep percolation, and distribution uniformity were 58.2%, 41.8%, and 89% under 1ls^-1 inflow rate respectively, and 54.3%, 45.7%, and 91% under 1.5 ls^-1 inflow rate respectively for 100 m furrow length with 0.2% bed slope. This indicates the hydraulic performance of the furrow irrigation system of the study area was poor, even though the greater performance was attained under 1ls^-1 inflow rate compared to 1.5 ls^-1 inflow rate, Finally, the optimum combination of furrow hydraulic parameters should be identified and suggested for effective management and use of irrigation water to improve performance of furrow irrigation of the study area.

It is critical to assess land suitability for irrigation to make efficient and effective use of limited resources for agricultural production that is sustainable. Using a geographic information system, the researchers determined the physical irrigation suitability of the Sibilu River watershed. The most suitable land was determined using a weighted overlay of irrigation suitability characteristics such as slope, soil, and land use land cover. A double mass curve was used to check for inconsistencies in the data, and the normal ratio approach was used to fill in the missing metrological data. The final irrigable land was found by weighting the elements of appropriateness, which were categorized based on the food and agricultural organization standard for land evaluation into highly suitable, moderately suitable, marginally acceptable, and not suitable classifications. According to the irrigation suitability analysis parameters, 56.5 percent of the slope, 19.3 percent of soil, and 89.82 percent of land use/cover area were all extremely suitable for surface irrigation. Overall, the weighted overlay analysis of these characteristics revealed that 57.53 percent of the research region was extremely favorable for irrigation development, whereas 0.42 percent was deemed to be unsuitable. In terms of adaptability parameters, the Sibilu River is very ideal for surface irrigation. However, because only 133 hectares could be irrigated, dry flows should be augmented or groundwater should be developed and water conserved to meet irrigation potential.

This article explains how to determine appropriate furrow length and flow rate for furrow irrigation system that is accurate and simple to use in semi-arid climates. The experiment was carried out from April to November 2019 and April to November 2021. Cotton was grown in Middle Awash, Ethiopia, thus field tests were conducted there. The yield and water productivity were significantly affected by the interaction of furrow length and inflow rate. Furrow length of 50 m combined with (1.2 l/s) inflow rate for 35.6 minutes produced the highest water application efficiency (65.0 %), water productivity (1.37 kg/m³), and lint yield (6.86 t/ha). The lowest water application efficiency (38.3 %), with inflow rate (1.6 l/s) for 9.75 minutes, and water productivity (0.85 kg/m³) were achieved from 10 m furrow length.

Water shortage is one of the major challenges faced by the current agricultural systems worldwide, especially in arid and semi-arid regions. The response of potato crops to moisture stress was evaluated in Ziway Dugda district for two consecutive years during the dry season. The objective of the study was to determine the effect of soil moisture stress at different growth stages on the yield and water productivity of potatoes. Fifteen treatments were combined and imposed at four growth stages. The experiment was arranged in a Randomized Complete Block Design (RCBD) with three replications. The combined result of two years indicated that, moisture stress imposed at different growth stages significantly (P<0.05) affected potato tuber yield, and water productivity. The highest tuber yield (19,521 kg/ha) was obtained at control treatments where all the growth stage is irrigated, this result is followed by a treatment receiving moisture stress only during the late season (19,516 kg/ha). On the other hand, the lowest tuber yield (5,663 kg/ha) was obtained when the potato crop was irrigated only during the initial season. The highest water productivity (8.70 kg/m³) and the lowest WP (3.56 kg/m³) were obtained when potato was irrigated only at the initial stage (T₁₅) and irrigated in all states except the mid-season stage (T₄). Treatments that received irrigation only at the initial stage showed better water productivity. Therefore, in areas where irrigation water is not limited potatoes should be irrigated in all growth stages (T₁), otherwise, irrigate potatoes only during the development stages or development and midseason to maximize water productivity.

This study was conducted to determine the response of onion to furrow irrigation method under different deficit irrigation levels on yield and water productivity. The experiment was laid out in RCBD with three replications. The treatments comprised alternate, fixed, and conventional furrow irrigation methods and 50%, 75%, and 100 % of Etc deficit irrigation levels. Onion bulb yield showed that, CFI method of 100% ETc had a significant difference over other treatments except the treatment receiving CFI 50% and 75% ETc. Maximum bulb yield of 18,022 kg/ha recorded from CFI receiving 100% of ETc and the minimum yield of 12,571 kg/ha was obtained from FFI 50% of ETc. The water productivity result showed that the maximum water productivity of 7.40 kg/m³ was recorded from treatment receiving 50% ETc AFI method and the minimum value of 2.38 kg/m³ was recorded from full irrigation (100% ETc CFI). Considering yield response (K_y) is a limiting factor, 50% ETc AFI treatment saves about 75% of irrigation water and has a yield penalty of 22.73% when compared with 100% ETc CFI. In conclusion, the association between 100% ETc and AFI method gave optimum bulb yield and water productivity and tolerable yield limit of 13.26%.

Population growth, high water competition (demand), and the effect of climate change have caused water shortage problems in the Nile basin. Therefore, improving water management and determine the water requirement of field crops is substantial. In this study, the Food and Agricultural Organization (FAO) CROPWAT 8.0 simulation model, local climate, and soil data were used to determine crop water requirement (CWR) and irrigation scheduling of wheat crop at Koga and Rib irrigation scheme. The CROPWAT Penman-Monteith and the United States Department of Agriculture (USDA) soil conservation service method were used to compute the reference evapotranspiration (ETo) and effective rainfall respectively. The result of the study showed that reference evapotranspiration was varied from 4.86 mm day-1 (maximum) to 3.14 mm day-1 (minimum) at Koga while at Rib it ranges from 4.67 mm day-1 (maximum) to 2.36 mm day-1 (minimum) during the study period. The effective rainfall was 156.5 mm at Koga and 160.5 mm at the Rib irrigation scheme. The irrigation requirement of wheat at Koga was 376.9 mm dec-1 while at Rib was 379.9 mm dec-1. The study showed that the CROPWAT model is an important tool to compute the crop water requirement of field crops in irrigated agriculture.