| The water resource per capita in China is only2100m3, which is only28%of the world average. Water deficit per year is more than5×1010m3, causing a prominent contradiction between the supply and demand of water resources. In the meantime, agricultural water consumption accounts for63%of the total water consumption, and irrigation water consumption takes up more than90%of the agricultural water consumption. By now, the irrigation water use efficiency factor is only0.50, which has a large gap compared with the world advanced level with0.70～0.80. As a result, water conservation and increase of irrigation water utilization efficiency determine the improvement of the water use efficiency of the whole national economic development, and is also the only road to sustainable development of our national economy.At present, the statement and measurement of irrigation water utilization efficiency are different around the world. Tracking assessment and management of water utilization efficiency at different scales are lacking of a systematic procedure and method, which will bring about certain negative effect to the implement of the tough water management measures. As a result, carrying out research on evaluation and management of irrigation water use efficiency for different scales systematically is of great importance.Based on that, the paper analyzed current situation of our country’s water resources and irrigation water. The relevant researches on irrigation utilization efficiency around the world are also analyzed so as to put forward the theoretical framework of evaluation and management of irrigation water utilization efficiency. Based on that, this paper put forward a theoretical method which uses "initial and ending calculation" to measure irrigation water efficiency factor-an important index to represent irrigation water efficiency, as well as theoretical method to evaluate irrigation water efficiency factor at three different scales of irrigation area, province and nation. This paper took Jiangsu province and its Chaitang large irrigation area as an example, and systematically stated the calculation process, result and evaluation of irrigation water use efficiency factor at different scales of irrigation area, province and nation. Temporal and spatial changing laws of irrigation water use efficiency factor were systematically analyzed. Using distributed hydrological model, Shijin large irrigation area was taken as a typical irrigation area and the threshold of its irrigation water use efficiency factor was analyzed. Finally, according to the general requirement of the tough water management measures, irrigation water use efficiency factor at the end of the12th Five-Year Plan was predicted and the factors in differentprovinces were decomposed. The monitoring and assessing thread and method werebrought out. The main achievements were as follows:(1) Relative researches on irrigation water use efficiency around the worldwere summarized systematicallyNow a days, researches and application on irrigation water use efficiency werestill not unified and not comprehensive. This paper pointed out the importance ofrationally define the assessment index of irrigation water use efficiency, normativelyunify the process and standard of analyzing and assessing the measurement,tracking and grasping the current situations of irrigation water use efficiency atdifferent scales, monitoring the changing trend of irrigation water use efficiency,carrying out strategies of water use efficiency macro-management and increasingwater use efficiency.(2) Theoretical method and influencing factors of irrigation water useefficiency factor at different scales of China were carried outThe definition of irrigation water use efficiency was clarified and it was statedthat irrigation water use efficiency factor was used as the index to characterizeirrigation water use efficiency. The method of initial and ending calculation wasintroduced to assess irrigation water use efficiency factor at different scales.Theoretical foundation, selection principle and methods of sample irrigation selectionwere brought out. Measurement and analyze network system of irrigation water useefficiency factor of our country based on sample irrigation area was established.Procedures and methods to assess irrigation water use efficiency factor from threeaspects of irrigation area, province and nation were established.Five aspects-natural conditions, irrigation types and size, irrigation projectstatus, irrigation technology, management level-which could affect the irrigationwater use efficiency factor were analyzed. The results showed that precipitation andirrigation water use efficiency factor usually have negative correlation in the sameplace; irrigation water use efficiency factor usually has negative correlation withirrigation area size; irrigation water use efficiency factor of pumping irrigation area isusually lower than that of well irrigation area; irrigation water use efficiency factor ofgravity irrigation district is usually lower than that of well irrigation area and pumpingirrigation area; main, engineering measures to increase irrigation water use efficiencyfactor are canal anti-seepage, pipe transport of water, etc.; main technical measures toincrease water efficiency in field are ridged field trim, sprinkler irrigation, microperfusion technique, improvement of ground irrigation technology, bubbler irrigation, etc.(3) Irrigation water use efficiency factors at different scales of irrigation area, province and nation were assessed systematicallyThis paper took Jiangsu province and its Chaitang large irrigation area as an example, and systematically stated the calculation process, result and evaluation of irrigation water use efficiency factor at different scales of irrigation area, province and nation. The results showed that among32provinces, there are9provinces (28%) whose irrigation water use efficiency factor is larger than0.55;15provinces (47%) whose irrigation water use efficiency factor varies between0.45～0.55;8provinces (25%) whose irrigation water use efficiency factor varies between0.35～0.45; according to irrigation water use efficiency factor, the6zones can be arranged from the highest to the lowest as North China, the Northeast, the Southeast, the Northwest, the Central and the Southwest. According to the analysis of the influencing factor to irrigation water use efficiency factor, the larger the size of the irrigation area is, the lower the irrigation water use efficiency factor will be and vice versa; the proportion of small and well irrigation area in a province has positive correlation with its irrigation water use efficiency factor; water-saving irrigation area plays a very important role in the increasing of irrigation water use efficiency factor; enhancing water management could increase irrigation water use efficiency factor significantly. As to well irrigation area, micro-irrigation, sprinkling irrigation, pipeline ground irrigation, canal anti-seepage ground irrigation, soil-canal ground irrigation arranges form the highest to the lowest according to their contribution to the irrigation water use efficiency factor.(4) Temporal and spatial changing law of irrigation water use efficiency factor was systematically analyzedTemporal and spatial changing law of irrigation water use efficiency factor from2006to2010was systematically analyzed. From the temporal aspect, irrigation water use efficiency factor of each province showed a slow increasing trend and as time goes by, the increase of irrigation water use efficiency factor will be limited and it will become more difficult to improve on. From the spatial aspect, Huanghuaihai plain has a larger factor, Qinghai-Tibet Plateau and Yunnan-Guizhou Plateau have a smaller factor. In the meantime, for places in the same latitude area, developed area usually has a larger factor compared to the undeveloped area. The irrigation water use efficiency factor of the Southwest, Northwest and the South generally increased much more than that of the East and the Northeast area; for provinces who have rich waterresources and slower economy, their irrigation water use efficiency factors did notincrease much. Under hypothesis that all the other conditions are the same, the changerange of irrigation water use efficiency factors in large irrigation area is about650km,with strong spatial variability.(5) The threshold of irrigation water use efficiency factors of Shijinirrigation area was systematically analyzedWith the help of distributed hydrological model, water cycle process of theearth’s surface, soil, underground of Shijin irrigation area were simulated and theirrigation water use efficiency factors was0.535under current situations. Irrigationwater use efficiency factors for canal irrigation district, well-canal irrigation area andwell irrigation area were0.380,0.476and0.689respectively. The water cycle changein different water-saving situations was simulated and their irrigation water useefficiency factors were also calculated. Main factors which affect the irrigation factorsand their impact were analyzed. Associated effects of multiple-measurements wereevaluated. Finally the threshold of irrigation water use efficiency factors of Shijinirrigation area was calculated as0.64, within which the threshold of irrigation wateruse efficiency factors for canal irrigation area, well-canal irrigation area and wellirrigation area were0.57,0.62and0.76respectively.(6) Integrated management countermeasure controlling our country’sirrigation water use efficiency was first carried out preliminarilyUnder the severe situation of our country’s water resources, the importance toenhance integrated management of irrigation water use efficiency was stated in orderto implement the tough water resources management measures. The results showedthat till2015, it is feasible to increase the irrigation water use efficiency factor to over0.53. Using factor analysis and trend analysis approach, irrigation water use efficiencyfactor from2011to2015were decomposed. The monitoring scheme of irrigationwater use efficiency factor of the whole country was carried out. According to therequirements of water use efficiency, work thinking, method, main content ofexamination and main supporting measures of the objective assessment of irrigationwater use efficiency factor were brought out. In the meantime, targeted strategies ofeach zone to increase irrigation water use efficiency factor were carried out.In the further study, researches on influencing factor and threshold of irrigationwater use efficiency factor should be enhanced. Dynamic assessing and monitoringsystems on relative indexes based on remote sensing should be further discussed. More thorough water use efficiency controlling management should be established so that the tough water resources management measures can be indeed put into practice. |
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