Development Strategy On Systematic Design Of Water Saving Projects In Key Medium-sized Irrigation Areas In China

China is a large agricultural country, as the major grain production base, irrigationdistricts development is very important; especially key medium-sized irrigationdistricts have been playing an important role in regional agricultural economydevelopment because of its large quantity and widespread. Most of the irrigationdistricts were built in1970s, lots of problems are emerging such as low criteria, projectaging and disrepair, low water utilization efficiency, and so on. Those results showthat continuous auxiliary projects construction and water saving reformation isnecessary in key medium irrigation. Further, assessment on demand urgency torehabilitation and water saving reformation of key medium-sized irrigation districtsis an important basis for water saving reconstruction and resources optimization.Assessment on demand urgency of rehabilitation and water saving reformation of keymedium-sized irrigation districts includes two parts: assessment index and assessmentmethod, which is involving water conservancy engineering, systems engineering andmathematic methods. Considered various influence factors and the variable fuzzy setstheory was introduced, which includes non-linear simulation, half-constructionassessment, multi-objects decision making, assessment on urgency demand rehabilitationand water saving reformation was built in this paper. The main research contents andachievements are as follows:(1) Based on analysis of agricultural water use and achievements of continuousauxiliary projects construction and water saving reformation, the main problems issummarized according to key medium-sized irrigation districts distribution in china.Considered sub-area differences, all key medium-sized irrigation districts are dividedinto5partitions. Further more, water and soil resources characteristic and the mainproblems in current projects and management are distinguished and summarized in eachsub-area.(2) Different sub-area has different problems and reformation importance. Throughquestionnaire, expert judgment, influence factors analysis about continuous auxiliaryprojects construction and water saving reformation,25indixes are selected to establishthe assessment system. The assessment system is a two-layer structure, which consistsof5subsystems: water resources development and utilization, project, management,economic benefits and ecology. And then, indices definition, calculation formula,quantitative criteria and assessment model are all presented. Furthermore, each sub-area's assessment standard, threshold value and entervals were given in the paper.(3) Several indexes of assessment index system are difficult to define in practice,for example, irrigation water efficiency. Based on15group investigation data from keymedium-sized irrigation districts, the fuzzy optimization neural network model wasapplied to train and simulate the water efficiency of irrigation. Here, number of hiddennodes of neural network structure is trained from2to7. And when number of hidden layernodes is3, the training precision is highest. The simulation results could provide abasis for the assessment of key medium-sized irrigation district.(4) The variable fuzzy sets theory and binary comparison method were introduced,and assessment mathematic model on demand urgency of rehabilitation and water savingreformation was built based on variable fuzzy sets theory. Especially, QUANMIN irrigationdistrict was assessment in detail in The Yangtze River Plain and Hills area as an example.Five key medium-sized irrigation districts are selected to assessment according to5sub-areas. The assessment results determined demand urgency of rehabilitation and watersaving reformation of every sub-area. Moreover, problems and missions were indicatedin5key medium-sized irrigation districts through index analysis, which could provideexamples for the further evaluation work.(5) The principles and strategies of rehabilitation and water saving reformationwere established. Consided5sub-areas regional feather, existing problem, andrehabilitation objective, the technology on rehabilitation and water saving reformationwere summarized into4categories: project, water resources optimal allocation, farmingpattern adjustment and water management. From the point of the core technology and thecorresponding supporting technology to those key problems,8patterns of rehabilitationand water saving reformation were extracted and summarized from practical, useful andacceptable technologies, Moreover, relevant policy and management was suggested.Finally, a summary is given and some problems to be further research are discussed.