Irrigation & Drainage Systems Engineering

A review of the past studies has demonstrated that rehabilitation of an irrigation scheme through infrastructural development and agricultural production value chains alone will not sustain the targeted agricultural production unless scientific principles, aimed at enhanced water use efficiency are incorporated in the development agenda to avoid future water losses and shortages. In Nguruman, the available water supply has the capacity to meet irrigation water requirement of 5,332,809 m3 to irrigate the targeted 800 ha per year. However, with increasing number of farmers engaging in irrigated agriculture, more area is expected to be brought under irrigation to meet the increasing food demands, thus requiring significant amount of water savings through enhanced water use efficiency. For this reason, analysis and review of the irrigation design challenges, operational realities and technological options for improved water use efficiency was carried out in terms of the quantities of water saved and additional area that can be irrigated by each of the technological options considered in relation to the farmers’ irrigation methods. The technological options reviewed were: drip plus digital instruments; drip plus analog instruments; sprinkler plus digital instruments; sprinkler plus analog instruments and farmers’ irrigation method. It was deduced from literature review that drip plus digital instruments, drip plus analog instruments, sprinkler plus digital instruments and sprinkler plus analog instruments could save 465,600, 433,132, 365,520 and 323,637 m3 of irrigation water respectively relative to the farmers’ method. The additional area to be irrigated using water saved from drip plus digital instrument, drip plus analog instrument, sprinkler plus digital instrument and sprinkler plus analog instrument was 146.3, 136.7, 115.4 and 104.1 ha respectively. Since drip irrigation plus digital instrument had the highest water saving potential, it was identified as the most appropriate technology to be used tested, validated and applied to irrigate more land with less water in Nguruman Irrigation Scheme.

Application of water to crops during the dry season in areas of scare water supply is very important to meet the food demand of the ever-increasing population globally. Thus, modified irrigation technique that poor resource farmers can afford and use easily was evaluated in this paper. A field experiment was conducted at the University of Ibadan Teaching and Research Farm to evaluate the performance of okra under modified bucket drip kit (BDK) and wateringcan (WC) methods of irrigation for three growing seasons between 2011 and 2013. The BDK irrigation treatment had a higher mean percentage plant survival (92.9%) than those under the WC method (90.7%). The number of okra leaves, plant height and stem diameter were consistently higher under BDK irrigation than under WC irrigation for the three growing seasons. Harvested number of fresh fruits was only significantly higher under BDK method than WC method by 40.8% and 11.1%, respectively, for the second and third seasons. The plots under BDK irrigation system produced higher fresh fruit weight than the WC method by 0.1, 1.1, 7.4 t ha-1 respectively for the first, second and third seasons. The BDK performed better than WC in terms of okra growth and yields.

The objective of this paper is to find a simple and efficient drip irrigation schedule for cotton under film mulching using a homemade evaporation pan with a diameter of 60 cm. A field experiment was conducted to study the responses of cotton growth, seed cotton yield, water consumption and water use efficiency to drip irrigation amounts of 0.5 Ep (pan evaporation), 0.7 Ep and 1.0 Ep at the Irrigation Experiment Station of the Water-conservancy Bureau in Xinjiang Production and Construction Corps in Urumqi, Xinjiang province during the cotton growing seasons of 2007 and 2009. The feasibility of the drip irrigation scheme based on surface water evaporation by using a homemade evaporation pan was analyzed. The results showed that continuous water deficit at the bud and boll stages (irrigation quota equal to 0.5 Ep) produced negative effects on cotton growth, seed cotton yield and the water consumption process during the entire cotton growth period with drip irrigation under mulching compared to the sufficient irrigation treatment (irrigation quota equal to 1.0 Ep); the effect of timely and appropriate water deficit during the bud and boll stages (irrigation quota equal to 0.7 Ep and 0.5 Ep, respectively) on seed cotton yield was not significant; 22.78%~24.88% of the irrigation water was saved, while irrigation water use efficiency was improved by 27.94%~34.85%. It is suggested that the irrigation model with light water deficit during bud emergence (irrigation quota equal to 0.7 Ep), severe water deficit at the late flowering and boll stage (irrigation quota equal to 0.5 Ep), and sufficient water supply at the early flowering and boll stage (irrigation quota equal to1.0 Ep) is a convenient, high-quality, efficient drip irrigation pattern that can be used as a suitable irrigation approach to cotton production with drip irrigation under film mulching in Xinjiang.

Exploitation of irrigation water under arid ecosystem conditions becomes the pedagogical problem; therefore, rationalizing irrigation and maximizing water use efficiency based on appropriate developed technologies are the most important aspects in the water and agricultural policies. Therefore, the objectives of this study were to: 1) develop out a criterion to identify irrigation system effectiveness by using a dimensionless analysis; and 2) validate the suggested criterion. Dimensional analysis outputs revealed that the irrigation efficiency, may be better if it replaced by new developed terminology noted as irrigation effectiveness for calculating the seasonal crop water requirements (SCWR) that represent a ratio of irrigation system performance and irrigated soil characteristics. The developed criterion may be expressed as follows: Moreover, results analysis of the validation process of the application of the developed criterion indicated that SCWR had been improved by applying the developed criterion with about 10.55 – 21.56% comparing with the conventional method that had been recommended by FAO.

Evapotranspiration has a vital importance in water resources planning and management. In this study, the applicability of six different multi-layer perceptron (MLP) algorithms, Quasi-Newton, Conjugate Gradient, Levenberg- Marquardt, One Step Secant, Resilient Back propagation and Scaled Conjugate Gradient algorithms, in modeling reference evapotranspiration (ET0) is investigated. Daily climatic data of solar radiation, air temperature, relative humidity and wind speed from Antalya City are used as inputs to the MLP models to estimate daily ET0 values obtained using FAO 56 Penman Monteith empirical method. The results of the MLP algorithms are compared with those of the multiple linear regression models with respect to root mean square error (RMSE), mean absolute error (MAE), Willmott index of agreement (d) and determination coefficient (R2). The comparison results indicate that the Levenberg-Marquardt is faster and has a better accuracy than the other five training algorithms in modeling ET0. The Levenberg-Marquardt with RMSE = 0.083 mm, MAE = 0.006 mm, d = 0.999 and R2 = 0.999 in test period was found to be superior in modeling daily ET0 than the other algorithms, respectively.

The aims of this study were to develop out crop and water-stress coefficients of onion crop under deficit conditions of arid regions. Therefore, field experiments of fully irrigated and deficit conditions with standard agronomic practices of onion crop had been conducted in two successive growing seasons in 2011-2012 and 2012-2013 in order to develop out the crop coefficients of onion plants at different growing stages. Results revealed that crop coefficient values at different growing stages under different management parameter considerations indicated that the observed values of kc are ranged above and dawn of the estimated values of FAO. Meanwhile, data analysis revealed that a general trend of increasing CWU and attributed SCWR from the beginning of cultivation up to the end of bulb formation stage (72 days after sowing seeds), then it decreasing within bulb enlargement and maturity stage.

The rational use of irrigation water and the production of energy from renewable sources are among the major concerns of the international scientific community in recent years. Against this background, the Agricultural Hydraulics Laboratory of the University of Thessaly conducted research related to the effect of two different irrigation methods in the production of biodiesel from sunflower crop. Two treatments were organized, in four replications for the growing seasons of the years 2011 and 2012. The treatments were: a) the surface drip irrigation in which the irrigation was scheduled by the Penman-Monteith method and b) the surface drip irrigation in which the irrigation was scheduled by an automatic evaporation pan.

Field experiment was conducted at Melkassa Agricultural Research Center with the objectives to determine the optimal irrigation levels for maximum tomato production and to assess the effect of limited water supply on field grown tomato yield and to estimate ‘yield response of tomato to soil water (Ky)’ and to validate CropWat irrigation model using the data for tomato cultivation during hot-dry season conditions. Three irrigation scheduling levels such as 1) 100% of crop water requirement (ETc) (Full irrigation) 2) 80% ETc (Full) (= 0.80 ETc) and finally 3) 60% ETc (= 0.60 ETc) were used using drip irrigation replicated three times; the tomato was subjected to various levels of water stresses over whole growth period. Yield data such as marketable, unmarketable and total fruit yield were collected at each harvesting and summed at the end of harvesting. The results of data analysis showed that use of various irrigation depth brought a significant effect (P<0.01) effect on the marketable yield of tomato whereas application of various irrigation depths did not bring significant difference (P<0.05) on unmarketable fruit yield of tomato. Use of various irrigation depths had a significant effect (P<0.05) on the total fruit yield of tomato. The mean separation indicated that the highest fresh fruit yield was obtained from full irrigation and the lowest was obtained from 60% irrigation. Thus, the total fresh fruit yield obtained from fully irrigated tomato plot exceeded the fresh fruit yield obtained from tomato plot irrigated with only 60% of full irrigation water by 62.8%. The results showed that with decrease in the depth of irrigation, there was a decrease in total fruit yield in tomato due to reduced uptake of water. The yield response (Ky) of tomato throughout the crop cycle was calculated and found to be 0.999, indicating that the yield reduction is directly proportional to reduced water use. Then the CropWat irrigation model was validated using field data for tomato cultivation. Accordingly, the efficiency of the model was found to be 94%, indicating that the model is a useful decision support system to help tomato growers