Evaluation the performance of irrigation and drainage networks using analytical hierarchy process (AHP) (Case study; Zohreh-Jarahi and Gotvand utilization companies in Khuzestan province)

Study, design, construction and operation of irrigation and drainage networks are small part of the purpose of the network construction. The main purposes are operation, maintenance, optimal efficiency achievement due to performance which are only obtained by monitoring and evaluation of networks. Evaluating performance of irrigation and drainage, if it based on a personal idea, will limit by the comparison of simple indicators such as yield per unit area. But many groups are involved in irrigation and drainage networks. So the methods which consist of wide range of information and ideas should be applied. Khuzestan province, with an area equal to 64, 057 square kilometers in the southwest of Iran has third of total surface water resources of Iran. Existence five Main River (Karoon, Dez, Karkheh, Maroon and Zohreh-Jarahi) and fertile lands are the most important natural features in Khuzestan province. In contrast to, high levels of land salinity and water table are the limiting factors for agricultural activities. In addition, in this area agricultural products can be planted in the four seasons of the year. Development of agriculture in this region with saline soils, ground water and climatic conditions requires design, implementation, operation and maintenance of the irrigation and drainage networks. In recent years, significant measures have been done in this regard. Unfortunately after construction, due to lack of evaluation and monitoring systems despite the huge costs of the network, the desired result have not obtained. There are various methods for evaluating systems. One of these tools is analytical hierarchy process. In this method are used complex of criteria, sub-criteria, options and the idea of different kind of person who related to the subject.
To evaluate the irrigation and drainage networks of Khuzestan Province was used analytical hierarchy process. For this purpose, the irrigation and drainage networks of Zohreh-Jarahi and Gotvand companies were selected. The networks consisted of Shahid Rajae, Hendijan, Ramshir, Shahid Hemat of Shadeghan, Aghili, Gotvand, Daymcheh, Molasani, Salamat and Mianab. In order to evaluate the networks, criteria, sub-criteria and options were defined. Seven factors including; structure, irrigation, drainage, climate, economy, territorial and socio-cultural were chosen as criteria. Finally, 29 factors were selected as sub-criteria for evaluation of ten options. In order to select the criteria, sub-criteria and options the experiences and references were used. For collecting the information, a total of 100 questionnaires based on the criteria and sub-criteria were completed. According to the results of the questionnaire, geometric matrix of the main criteria, sub-criteria and options were formed. Then the information was transferred to Export Choice software and weight of the criteria, sub-criteria and options were determined.
The results showed that the main criteria for both structural factors and irrigation have the highest weight equal to 37.5% and 30.7% respectively. Among the sub-criteria, the canals sedimentation (40.1%), crop water requirement (30.5%), the drainage condition (73.2%), evapotranspiration (70.6%), the price of the product (35.7%), the equipment and the modernization of farms (31.1%) and water user organizations (69.8%) have the highest weight. The sub-criteria is dependent on structural, irrigation, drainage, climate, economy, territorial and socio-cultural factors. In general, regardless of sub-criteria which was evaluated, the condition of drainage had the greatest weight. Current research indicated the importance of attention to sub-criteria for increasing the performance of irrigation and drainage network's efficiency. Sediment of channels, type and condition of gates, type and grade of channels, type and condition of water management structures and channels cover were considered as sub-criteria of structural factor. According to the results, sedimentation in the irrigation and drainage networks had the greatest effect on performance. Unfortunately, the channel dredging was not done according to a regular program and which was depended on the allocation of financial resources, regardless of which sedimentation of channels effect on the valve, water management and other structures. The irrigation criteria consist of water supply, irrigation supply relative allocation of water, crop water requirements, water allocation, water quality and quantity and the method of water distribution in networks. Crop water requirements, water quality and quantity as sub-criteria of mention criteria had the most weight in this group. The consequence showed the undisputed effect of the amount and quality of water in the network and its impact on the network performance, especially from the perspective of consumers. The results of the main criteria of climatic, economic, territorial and socio-cultural showed that evapotranspiration, the unit price of the product, area and water user organizations had the most significant influence on the performance of irrigation and drainage networks in the study region. The results showed that Aghili irrigation and drainage network accordance with the criteria and sub-criteria had the better situations. Also, the assessments of mention networks determined that Gotvand utilization company conditions were favorable as Zohreh-Jarahi Company. Finally, after performing AHP, in addition to the weights, Consistency Ratio (CR) were evaluated. The acceptable result was obtained when the amount of CR was less than 1.0. In the current research, the amount of mention parameter was 0.07 which was indicated acceptable results.