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Chen H.-R.,Wuhan University | Chen H.-R.,China Institute of Water Resources and Hydropower Research | Chen H.-R.,National Center for Efficient Irrigation Engineering and Technology Research Beijing | Huang J.-S.,Wuhan University | And 2 more authors.
Shuikexue Jinzhan/Advances in Water Science | Year: 2011

A comprehensive review of scale effect(SE) on the irrigation water use efficiency(IWUE) is presented in this study, including the definition and its causes as well as the upscaling techniques. SE is the composite outcome of two main causes that refer to reusing irrigation return flow and the spatial variability of local properties such as soil, crop, climate, irrigation structures, and amount of irrigation water and others. The existing indices of irrigation water use efficiency should be extended to including the connotation of water supply efficiency. Reusing irrigation return flow should be considered together with the economic constraint. The existing studies on scale effects show that the regularity with regard to indices of irrigation water use efficiency is not conclusive due to the complexity of nature conditions. Regarding to upscaling problem, the two main causes have been taken into account separately and need to be synthesized in the future studies. A reliable and practical upscaling formula is still unavailable for use to improve the practice of water management. Many efforts should be devoted to the theory of scaling as well as the scale effect of accompanying courses with the water cycle, based on the improvement of irrigation water use efficiency assessment indices. Source


Chen H.-R.,China Institute of Water Resources and Hydropower Research | Chen H.-R.,National Center for Efficient Irrigation Engineering and Technology Research Beijing | Wang S.-L.,China Institute of Water Resources and Hydropower Research | Wang S.-L.,National Center for Efficient Irrigation Engineering and Technology Research Beijing
Proceedings - 2013 4th International Conference on Digital Manufacturing and Automation, ICDMA 2013 | Year: 2013

Global climate changes and human activities have a profound impact on disaster environment and formation mechanism of waterlogging disaster, exacerbating the uncertainty of waterlogging disaster and highlighting complexity and difficulty coping with the water disasters of farmland. A large number of researches on risk assessment and prediction of flood disaster have been carried out at home and abroad, and this study concluded the research progress of this direction in recent years in terms of six aspects including the connotation of disaster risk, comprehensive assessment of flood risk based on index system, the numerical models of flood disaster risk assessment, the regularity analysis of different carriers, the influence of environment changes on flood disaster risk and uncertainty of flood disaster and finally analyzed problems in the research and the future directions of development. © 2013 IEEE. Source


Cai J.,China Institute of Water Resources and Hydropower Research | Cai J.,National Center for Efficient Irrigation Engineering and Technology Research Beijing | Xu D.,China Institute of Water Resources and Hydropower Research | Xu D.,National Center for Efficient Irrigation Engineering and Technology Research Beijing | And 3 more authors.
Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery | Year: 2015

The messages of crop water deficit, soil moisture and field meteorology are the fundamental data to meet the needs of water saving, good quality and high yield in modern field irrigation management. Above all, it is very important to obtain these data at the same step in real time. A field monitoring system in real-time was presented which could support the data of crop canopy temperature, environment message and soil moisture at 1 h interval. It was powered by solar panel and controlled with a microprocessor to manage the data collection and storage.The configured sensors included infrared temperature, air temperature and humidity, soil water content, soil water potential and temperature. The infrared temperature sensor was installed at the end of the cantilever arm fitted on the upright stainless steel rod. It had a 45° inclination angle of the cantilever arm to scan the temperature of underlying surface. Each time, it collected multiple spot at 36° interval above the crop canopy and went back to the original location. Therefore, the average value of the canopy temperature would be more precise than that of the single detection. The rapid locking device could adjust the cantilever arm and sensors to the suitable position following the stainless steel rod, according to the need in different crop growth seasons. After the analysis of the monitoring data, all of these could describe the refined crop actual circumstance in the field and they can be used in irrigation decision-making and irrigation management. Moreover, how to separate reasonably the surface temperature occurred from infrared data scanned and determine the dependable threshold values of irrigation decision-making indexes, are the key points in the next step. © 2015, Chinese Society of Agricultural Machinery. All right reserved. Source


Wang S.,China Institute of Water Resources and Hydropower Research | Wang S.,National Center for Efficient Irrigation Engineering and Technology Research Beijing | Liu D.,Hunan Hydro & Power Design Institute | Xu D.,China Institute of Water Resources and Hydropower Research | And 3 more authors.
Paiguan Jixie Gongcheng Xuebao/Journal of Drainage and Irrigation Machinery Engineering | Year: 2015

An index system is put forward to evaluate the reuse suitability of farmland drainage water in arid and semi-arid regions threatened by salinization based on fuzzy pattern recognition model. For each index, the range of standard value for every classification is specified by analyzing the relevant literature and existing technical standards comprehensively. The weight of each index is determined by making use of the analytic hierarchy process (AHP). The index system is applied to assess the reuse suitability of drainage water in five typical farmlands in Yinbei Irrigation District, Ningxia. It is shown that except Qianjin farmland the water reuse suitability in the rest farmland is all at the second grade. Particularly, the index values in the middle and late periods of irrigation are less than those in the early period of irrigation, suggesting the water reuse suitability is better than in the middle and late periods. In the middle and late periods, crops need more irrigation but fresh water is in shortage; further the crops are not sensitive to salt. Thus it is feasible to reuse a certain amount of drainage water for irrigation in those periods. ©, 2015, Editorial Department of Journal of Drainage and Irrigation Machinery Engineering. All right reserved. Source


Liu G.,National Center for Efficient Irrigation Engineering and Technology Research Beijing | Liu G.,China Institute of Water Resources and Hydropower Research | Liu Y.,National Center for Efficient Irrigation Engineering and Technology Research Beijing | Liu Y.,China Institute of Water Resources and Hydropower Research | And 2 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2011

Evapotranspiration (ET) temporal upscaling method plays an essential role in ET remote sensing. In order to compare the performance of evaporative fraction method, crop coefficient method and canopy resistance method to upscale daily ET from daytime measurements, the daytime variation of evaporative fraction, crop coefficient and canopy resistance were investigated and the performance of three methods were assessed. The field work was carried out in Daxing district under winter wheat surface from March to June and the ET data was measured by eddy covariance. The results showed that the crop coefficient was more constant during daytime than evaporative fraction and canopy resistance, and the closeness of daily value and hourly value for crop coefficient was better than other two parameters. Meanwhile, the crop coefficient method performed better to upscale daily ET than other two methods. It is recommended to choose crop coefficient method to upscale daily ET data for the areas with similar climate, underlying surface conditions and data with similar spatial scale in Daxing district. Source

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