Irrigation & Drainage Systems Engineering

Optimal cropping pattern decisions without consideration to water supply uncertainty would result in yield/benefit that is less than expected and probability of system failure in meeting a given irrigation demand. In this study, a chance constraint linear programming (CCLP) model was used for optimizing cropping pattern for major crops grown at Koga Irrigation scheme, Ethiopia. The model incorporated uncertainty of inflow at exceedance probability of 90%, 80%, 70%, 60% and 50%. The model objectives were yield and benefit maximizations subject to land and water availability constraints. Each objective function has four scenarios. The models were solved using LINGO14. The cropping patterns under yield and benefit maximization models were found to be identical under all scenarios. However, the cropping patterns of each model varied among scenarios. The study showed that the possibility of irrigating 5904.3 to 8051.0 hectares of land at 80% by optimizing cropping patterns at irrigation efficiency of 48%. This could increase the yield by 108 to 153%, benefit by 153 to 208% and physical water productivity by 132% to 186% and economic water productivity by 205% to 241% of the actual values. In conclusion, the irrigated land in 2012/13 was below the optimal value and the irrigation water was mismanaged. Therefore, with optimal crop planning and water management, the design command area of 7000 ha could be irrigated. Finally, a study should be made to determine optimal levels of crop water deficit that maximize water productivity.

A review on agricultural effects of restricted soil drainage conditions is presented, related to soil physical, chemical and biological properties, soil water availability to crops and its effects on crop development and yield, soil salinization hazards, and the differences on drainage design main objectives in soils under tropical and semi-arid water regime conditions. The extent and relative importance of restricted drainage conditions in Agriculture, due to poor irrigation management is discussed, and comprehensive studies for efficient drainage design and operation required are outlined, as related to data gathering, revision and analysis about geology, soil science, topography, wells, underground water dynamics under field conditions, the amount, intensity and frequency of precipitations, superficial flow over the area to be drained, climatic characteristics, irrigation management and the phenology of crop productive development stages. These studies enable determining areas affected by drainage restrictions, as well as defining the optimal drainage net design and performance, in order to sustain soil conditions suitable to crops development.

The government is making all efforts to provide conducive atmosphere, level playing ground and policy support to enable the SSIs sector to achieve higher levels of production, exports and employment. The small-scale industry evokes different meanings for different agencies and the financial institutions. However, the definition of small industry is an important aspect of government policy as it identifies the target groups. The Micro, Small and Medium Enterprises Development Act, 2006 was enacted on 16th June 2006. The Act has empowered the government to establish a National Board for micro, Small and Medium Enterprise. The small-scale sector has been assigned an important role in the industrial economy of the country on account of some of its inherent advantages like low capital intensity, high employment generation capacity, regionally balanced development and even distribution of wealth and income. There are two types of small-scale industries for which registration certificates are issued by the Department of Industries and Commerce as per the guidelines issued by Development Commissioner, Government of Indi, and New Delhi. The Industrial Policy Resolution, Five Year Plans and recommendation of different committees on SSIs focus on the need for adequate and timely delivery of credit to the SSIs sector by commercial banks. The increase in the working capital limits, as suggested by different committees on the financing of SSI units, would ease the flow of bank credit to the small-scale industry.

The increasing dependence on groundwater for growing staple food crops like paddy causes lowering of water table and serious depletion of groundwater storage in many parts of India including Tamil Nadu, a southern Indian state. This study is based on field research conducted during the Kharif seasons in 2011-2013 in Villupuram district, Tamil Nadu, to evaluate the impact of TN-IAMWARM Project’s adoption of SRI on agronomic productivity and irrigation water use efficiency. The adoption of SRI method in paddy cultivation has resulted in increased by 20% in paddy yield and net income 44.50% over the conventional cultivation. This has been achieved with substantial reduction in irrigation water application (42.33%), labor input (17.46%) and seed cost (87.47%). The economic attractiveness of SRI cultivation is very high, giving farmers a strong incentive to accept water-saving techniques as a new norm for irrigated paddy production. Hence, the cultivation of Kharif paddy (which is a high water consuming crop) through SRI practices promises to be a significant alternative for not only increasing paddy productivity, but also for savings on irrigation water and energy costs in the resource-starved regions of India.

Blocking of diversion intakes and canals by sediment deposition is a widespread problem in many spate irrigation (flood water farming) systems. In the Gash Spate Irrigation Scheme (GSIS), particularly the Fota block, sedimentation is a continuous challenge that resulted in 75% reduction of the irrigable land (2012 data). The scheme receives sediment laden flood water from the Gash River which originates from the Eritrea-Ethiopia Plateau. The GSIS is the breadbasket for the Eastern Region of Sudan with over half a million inhabitants. This research focused on sedimentation problem and its remedial measures at Fota diversion intake. The sediment deposition in front of Fota diversion intake reached up to 1.5 m depth. This deposition at the diversion intake plus sedimentation in the canal networks reduces the Fota block irrigable land by 75%. Therefore, providing remedial measures to the sedimentation problem at Fota intake would directly impact the livelihood of 100's of poor farmers. The sedimentation at the vicinity of the diversion intake was analysed using a Delft3D model. The model was calibrated and validated using observed water levels at Fota diversion intake, with a coefficient of determination (R2) of 85% and 72% respectively. The model result under existing condition showed a 1.6 m sediment deposition at the main intake which in fact is the real situation on the ground. Alternative, sediment remedial measures based on local knowledge of farmers and technicians were modelled. Sedimentation at the intake could be reduced to almost zero if additional three Spurs (100 m, 50 m and 120 m long) are constructed on the opposite bank of the diversion at 25 m, 100 m and 200 m upstream the diversion structure respectively, and increasing the intake sill level by 1 m.

Freshwater ecosystems have suffered a long history of anthropogenic disturbances that are responsible for declining fish populations. Fish populations in irrigation channels, in particular, still remain unprotected and relatively unstudied. This study looked to investigate what environmental variables and anthropogenic disturbances had the greatest influence on fish species distribution in irrigation channels. Fish sampling and environmental data collection was conducted throughout six municipalities, spanning 43 sites, in southern Fukuoka, Kyushu, Japan. A total of 37 fish species and 17 environmental variables were statistically analyzed using detrended correspondence analysis (DCA) and receiver operating characteristic (ROC) curve analysis. DCA results showed that channel width, channel substrate and submerged plants had a statistical correlation with fish species distribution. We believe proper management of irrigation channel substrate conditions and macrophyte cover will go a long way in supporting fish species biodiversity and reducing pressure from invasive species. ROC curve analysis revealed a disparity in the environmental preferences of endangered and invasive species. This result suggests that the distribution of endangered species in irrigation channels may be heavily influenced by invasive species. Further research must be done before drafting an effective management solution

Small-scale irrigation practices determine the level of food production and, to a great extent, the state of the food security. Considering its importance to the overall growth of the agriculture sector, the Government of Ethiopia gives special emphasis to enhance agricultural production through the promotion of small-scale irrigation schemes. This paper looks at the role of small-scale irrigation in promoting agricultural production and food security. It pays particular attention to the results of small-scale irrigation practices, issues that enhance or impede small-scale irrigation capacities and explore complementary strategies that enhance the development of small-scale irrigation. We use descriptive and regression analysis to examine the relationship between small-scale irrigation and agricultural production. Relying on a survey result and observations, we conclude that, small-scale irrigation schemes could significantly improve agricultural production and the status of food security.