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71.
Demand Forecasting for Irrigation Water Distribution Systems 总被引:1,自引:0,他引:1
I. Pulido-Calvo J. Roldán R. López-Luque J. C. Gutiérrez-Estrada 《Canadian Metallurgical Quarterly》2003,129(6):422-431
One of the main problems in the management of large water supply and distribution systems is the forecasting of daily demand in order to schedule pumping effort and minimize costs. This paper examines methodologies for consumer demand modeling and prediction in a real-time environment for an on-demand irrigation water distribution system. Approaches based on linear multiple regression, univariate time series models (exponential smoothing and ARIMA models), and computational neural networks (CNNs) are developed to predict the total daily volume demand. A set of templates is then applied to the daily demand to produce the diurnal demand profile. The models are established using actual data from an irrigation water distribution system in southern Spain. The input variables used in various CNN and multiple regression models are (1) water demands from previous days; (2) climatic data from previous days (maximum temperature, minimum temperature, average temperature, precipitation, relative humidity, wind speed, and sunshine duration); (3) crop data (surfaces and crop coefficients); and (4) water demands and climatic and crop data. In CNN models, the training method used is a standard back-propagation variation known as extended-delta-bar-delta. Different neural architectures are compared whose learning is carried out by controlling several threshold determination coefficients. The nonlinear CNN model approach is shown to provide a better prediction of daily water demand than linear multiple regression and univariate time series analysis. The best results were obtained when water demand and maximum temperature variables from the two previous days were used as input data. 相似文献
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灌区稻田控制排水对排水量及盐分影响的试验研究 总被引:23,自引:7,他引:16
宁夏银南灌区每年从黄河引水约16亿m3,其中超过一半的水量以排水形式退回黄河或湖泊湿地。监测数据显示目前排水的含盐量较低,排水过量现象严重,不仅导致了水资源的浪费,而且加剧了黄河及湖泊湿地的污染。造成这种现象的主要原因之一是现有灌区排水系统能力过剩。本文介绍了在该灌区水稻田进行的一项控制排水试验,研究了在生长期内抬高排水沟出口对田间排水和盐分变化的影响。试验结果表明,将深度为1m的排水农沟控制到60cm时,生长期内农沟地下排水量减少了50%左右。排水量减少后,田间地下水含盐量增长幅度仅为3.7%,远远低于影响作物生长的临界含盐量。因此,控制排水措施具有节约灌溉用水和减少农业非点源污染的重要意义。 相似文献
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Potential solutions to high soil salinity levels and waterlogging problems are investigated on a regional scale using calibrated finite-difference flow and mass transport modeling for a portion of the Lower Arkansas River Valley in Colorado. A total of 38 alternatives incorporating varying degrees of recharge reduction, canal seepage reduction, subsurface drainage installation, and pumping volume increases are modeled over three irrigation seasons (1999–2001). Six performance indicators are used to evaluate the effectiveness of these alternatives in improving agroecological conditions, compared to existing conditions. Predicted average regional decrease in water table elevation (as great as 1.93 m over the irrigation season) is presented for selected alternatives, as well as the spatial mapping of results. Decrease in soil salinity concentration (with regional and seasonal average reduction as high as 950 mg/L) is also predicted and mapped. Estimated groundwater salinity changes, reduction in total salt loading to the river, increase in average regional crop yield, and changes in net water consumption indicate the potential for marked regional-scale enhancements to the irrigation-stream-aquifer system. 相似文献
78.
Irrigation Hydrology: Crossing Scales 总被引:1,自引:0,他引:1
Hydrology is the science concerned with distribution, circulation, and properties of water of the earth and its atmosphere, across the full range of time and space scales. Subject matter ranges widely from chemical and physical properties to the relation of water to living things. Irrigation hydrology is constrained to analysis of irrigated ecosystems in which water storage, applications, or drainage volumes are artificially controlled in the landscape and the spatial domain of processes varies from micrometers to tens of kilometers while the temporal domain spans from seconds to centuries. The continuum science of irrigation hydrology includes the surface, subsurface (unsaturated and groundwater systems), atmospheric, and plant subsystems. How do we scale up highly nonlinear physical, chemical, and biological processes understood at natural scales to macro- and mega-scales at which we measure and manage irrigated agroecosystems? How do we measure, characterize, and include natural heterogeneity in scaling nonlinear processes? In this paper, we discuss scaling issues and related research opportunities in irrigation hydrology with the hope of helping the irrigation-drainage engineering/science profession better address scaling problems in formulating designs affecting irrigated ecosystems. 相似文献
79.
我省节水农业的技术体系与发展思路 总被引:4,自引:0,他引:4
本文论述了我省节水农业的重大战略意义,并提出出了节水灌溉技术体系和发展思路。 相似文献
80.
过临猗县闫家庄镇陈庄果园试点,对用涌泉灌、滴灌及微喷灌三种微灌技术进行比较,结果表明涌泉灌具有抗堵塞能力强、投资少、管理方便、使用寿命长等优点,应予优先推广 相似文献