Water Delivery System Planning Considering Irrigation Simultaneity

Time should be considered in carrying out the design and management of demand irrigation distribution systems. In this paper, a method to characterize the pumping flow in demand pressurized systems throughout the day and irrigation season is presented. This method considers the temporal evolution of water requirements during the irrigation season and water demand concentration in certain periods of the irrigation day due to different electrical energy charges. The model was established based on data from an actual water distribution network of an irrigation district in southern Spain. The results differed significantly from those obtained using approaches based on establishing a uniform working probability for the outlets of the water distribution network at all hours of the irrigation day, which underestimated the circulating flows or system capacity. The most probable pumping flow with uniform probability was 3.1 m3/s, a smaller value than those obtained in the off-peak and average energy tariff times (4 and 3.4 m3/s, respectively). The total energy head required at the booster pumping in each period of the irrigation season was simulated. 10,000 randomly chosen scenarios were simulated for each irrigation day and each energy tariff time. The heterogeneous vertical stratification between 50 and 103 m of the required piezometric head was obtained as a function of the demanded flow for the water distribution system. This paper includes a pump selection algorithm for recommending least cost or optimum pump combinations in the distribution network and to evaluate the system’s energy cost. The pump recommendations show that the optimal solution could have saved 41% of the pumping cost of the Fuente Palmera irrigation district.     

Estimating Daily Net Radiation over Vegetation Canopy through Remote Sensing and Climatic Data

Net radiation (Rn)=key variable in hydrological studies. Measured net radiation data are rarely available and are often subject to error due to equipment calibration or failure. In addition, point measurements of net radiation do not represent the diversity of the regional net radiation values which are needed for large scale evapotranspiration mapping. A procedure has been developed to estimate daily net radiation using canopy temperature, albedo, short wave radiation and air temperature. This procedure makes it possible to estimate Rn by combining information from satellite and local weather stations. Three different methodologies are presented to estimate net radiation. Comparisons between net radiation using the three methods resulted in average error ranging from 1 to 30% and standard error of estimate ranging from 1.06?to?5.34?MJ/m2/day.     

我省节水灌溉的发展思路

文中针对我省水资源日益紧缺，农业用水浪费严重的现状，探索性地提出我省节水灌溉方面的一些方法和措施，为我省农业节水可持续发展提供了参考。     

Monthly Water Resources and Irrigation Planning: Case Study of Conjunctive Use of Surface and Groundwater Resources

The Tehran metropolitan area is one of the mega cities of the world and has an annual domestic water consumption close to one billion cubic meters. The sewer system mainly consists of traditional absorption wells. Therefore, the return flow from the domestic consumption has been one of the main sources of groundwater recharge. Some part of this sewage is drained into local rivers and drainage channels and partially contaminates the surface runoff and local flows. These polluted surface waters are used in conjunction with groundwater for irrigation purposes in the southern part of the Tehran. In this paper, a systematic approach to surface and groundwater resources modeling in the study area, with its complex system of water supply, groundwater recharge, and discharge, is discussed. A dynamic programming optimization model is developed for conjunctive use planning. The objective function of this model is developed to supply the agricultural water demands, to reduce pumping costs, and to control groundwater table fluctuations. To develop the response function of the aquifers located in the study area, a mathematical model for simulation of the Tehran aquifer water table fluctuations has been developed and calibrated with the available data. Different scenarios are defined to study the long-term impacts of the development projects on conjunctive use policies and water table fluctuations. Comparison of the results showed how significant is the effects of an integrated approach to the surface and groundwater resources allocation in Tehran metropolitan area. The proposed model is a useful tool for irrigation planning in this region.     

桑干河灌区节水改造措施及效益分析

桑干河灌区由于年久失修，水资源浪费严重，为提高灌区灌溉效益，对灌区的节水改造十分必要。本文针对桑干河灌区目前存在的问题，通过渠系节水改造工程后，灌溉水利用系数由0．384提高到0．522，年节水量1021．9万d，完全满足向首都北京供水970万m^3的节水目标，节水效益显著，可促进灌区农业的持续发展。     

山西省潇河灌区渠首枢纽工程水文监测自动化研究

山西省潇河灌区属全国大型灌区,是山西省十大灌区之一.灌区自动化建设是水利信息化建设的重要组成部分,为提高灌区用水与输配水等方面的效率,有力地促进对农业水资源的高效合理利用,在灌区渠首枢纽工程水文监测自动化方面进行了分析研究.     

Automation of a Center Pivot Using the Temperature-Time-Threshold Method of Irrigation Scheduling

A center pivot was completely automated using the temperature-time-threshold method of irrigation scheduling. An array of infrared thermometers was mounted on the center pivot, and these were used to remotely determine the crop leaf temperature as an indicator of crop water stress. We describe methods used to automatically collect and analyze the canopy temperature data and control the moving irrigation system based on the data analysis. Automatic irrigation treatments were compared with manually scheduled irrigation treatments under the same center pivot during the growing seasons of 2004 and 2005. Manual irrigations were scheduled on a weekly basis using the neutron probe to determine the profile water content and the amount of water needed to replenish the profile to field capacity. In both years, there was no significant difference between manual and automatic treatments in soybean water use efficiency or irrigation water use efficiency. The automatic irrigation system has the potential to simplify management, while maintaining the yields of intensely managed irrigation.     

Coupled Surface-Subsurface Flow Model for Improved Basin Irrigation Management

The availability of a process-based coupled surface-subsurface model can lead to improved surface irrigation/fertigation management practices. In this study, a one-dimensional zero-inertia model is coupled with a one-dimensional unsaturated zone water-flow model: HYDRUS-1D. A driver program is used to effect internal iterative coupling of the surface and subsurface flow models. Flow depths calculated using the surface-flow model are used as Dirichlet boundary conditions for the subsurface-flow model, and infiltration amounts calculated by the subsurface model are in turn used in surface-flow mass balance calculations. The model was tested by using field data collected at the University of Arizona, Yuma Mesa, research farm. The maximum mean absolute difference between field-observed and model-predicted advance is 2?min. Applications of the coupled model in improved irrigation management are highlighted. In addition, the significance of the effects of soil moisture redistribution on irrigation water availability to crops and the capability of the coupled model in tracking those changes in soil water status over time are discussed using examples.     

冬小麦储水灌溉节水增产效果分析

储水灌溉是利用土壤水库调蓄作用，把地面水以较大灌水定额通过灌溉储存在土壤中的一种灌水方法。可以做到以丰补欠，秋冬水春夏用，汛期水非汛期用，提高水源利用率，达到节水增产目的。同时可以减少农田灌溉高峰期用水量，缓解工农业和作物间争水矛盾。本文以冬小麦储水灌溉试验为例，分析了储水灌溉节水增产效果及其机理，并给出了当地冬小麦储水灌溉适宜灌水时间、灌水定额及管理要求。     

不同水肥条件下硝态氮在土壤剖面中垂直分布规律研究

试验选择2块不同肥力的地块来研究冬小麦收获后硝态氮在1m土壤剖面中累积状况。研究结果表明:有机无机肥料配合使用能有效地降低硝态氮在土壤中的累积;硝态氮在肥力高的地块比在肥力低的地块累积量小;只有综合考虑施肥,灌溉等影响因子才能降低硝态氮在土壤中的累积。