Assessment of water delivery performance of Eski-Kelek irrigation system in Kurdistan

Population increase and the improvement of living standards brought about bydevelopment will result in a sharp increase in food demand during next decades. Mostof this increase will be met by the products of irrigated agriculture. At the same time,the water input per unit irrigated area will have to be reduced in response to waterscarcity and environmental concerns. In order to meet these projections, irrigationsystems will have to perform well and at their potentials.In developing countries, many irrigation systems perform below their potential and ingeneral regardless of the huge investments for the development of the infrastructure, theperformance of many irrigation systems is still low. This low performance may dependon the conditions that prevail at each system, but two of the major problems that can berelated to technical aspects, namely design and operation and maintenance, are commonto almost all systems in those countries. Efficient operation and maintenance of anirrigation system plays an important role in achieving good performance for that system.Performance assessment in irrigation and drainage can be defined as the systematicobservation, documentation and interpretation of activities related to agriculture withthe objective of continuous improvement. The ultimate purpose of performanceassessment is to achieve an efficient and effective use of resources and this can be donein a variety of ways, including operational performance assessment by system managersto determine how the operational processes are performing. The processes studied couldrelate to the overall production, or they could be broken down into sub-processes suchas main system water delivery, on-farm water delivery, crop production, etc.There is a need for improvement in the operation and maintenance of many irrigationwater delivery systems in Kurdistan. Although several canal automation algorithmshave recently been developed around the world that are ideal for improving irrigationsystem management; due to the lack of financial resources and infrastructures, theirapplication is presently difficult in most of the irrigation systems in Kurdistan.Therefore, hydraulic modelling of the irrigation canals will be a good tool forunderstanding the operational aspects that can assist in enhancing the overallperformance of these systems.An unsteady state hydraulic model (DUFLOW) has been applied to the Eski-Kelekirrigation system, Kurdistan, to assess, investigate and understand the water deliveryperformance under the exiting main canal operation rules and also to simulate andanalyse alternative operational scenarios to enhance the system operational performance.By inputting the collected climate data and existing cropping pattern for the system,irrigation water requirements have been calculated by using CROPWAT model. Thepresent gate opening rules used to control the offtakes have been simulated by theDUFLOW model and performance parameters (adequacy, efficiency and equity) whichwere used to judge the results of simulation were defined. The results show that thepresent rule is not optimal for the present system and has affected significantly theperformance. Oversupply occurs in nearly all service areas and the amount ofoversupply vary widely across the system, so the system is operated with a low waterdelivery efficiency. The irrigation agency for this system could improve control of the supplies to service areas to achieve the goal of reducing overall consumption. Theseobjectives, however, can only be achieved by changing the existing operational rules, i.e.changing gate setting for the main canal offtake gates together with lateral offtake gatesand cross structure. For this purpose four alternative operation options have beensimulated with the DUFLOW model and the results of the computer simulations arepresented by means of the previously defined performance parameters.In scenario one the flow in the main canal is simulated with DUFLOW and mainchanges in operation rules have carried out by adjusting gate opening for (main canalofftake, main canal check structure, and lateral offtakes) in different combinations,while in scenario two irrigation duration time has decreased from 12 hours to 6 hoursand comparison has been made between simulated flow from the model and calculateddemand. In contrast in scenario three a combination has made between two operationaloptions: changing application irrigation duration and setting the gates of lateral offtakes.Further more in scenario four attempts have been carried out to make some modificationin existing cropping pattern of the scheme by changing date of planting together withthe percent of land occupied by each crop.Scenario One part C and Scenario three represents more potential for providing a betterservice with higher water delivery efficiency. Efforts should focus in improving thedelivery strategies for Scenario four.Based on the results of the diagnostic analysis of the system operation in Eski-Kelek,the advantages and disadvantages of different scenarios will be discussed with Khabatirrigation Branch staff. The impact of a high groundwater table on salinity andproductivity of crops and the use of alternative scenarios to reduce hazards due to overirrigation will also be discussed with the staff and stakeholders (farmers).Executing these alternative scenarios during irrigation season needs discussions to becarried out with farmers' groups about the implications of the various operationaloptions for changing the operational rules of the system in order to achieve theperformance improvement goals