群井开采条件下承压含水层渗流动态模拟

根据有限差分方法 ,编制了承压含水层渗流模拟软件。对某水源地在群井开采情况下地下水渗流动态进行数值模拟。模拟结果显示 ,位于高渗区的井 ,压降漏斗较其它井大 ,压力下降快。当地层中存在裂隙时 ,平行裂隙方向压力下降比垂直裂隙方向要快得多。抽水初期 ,地层压力下降很快 ,以后 ,压力下降逐渐变缓 ,位于低渗透区的井逐渐不能满足流量要求。因此做好地下水资源规划十分重要     

非均质承压含水层分层井流量及水

针对MODFLOW处理承压含水层中混合开采井流量在各层分配上存在的问题,提出了流量权重迭代计算方法。该方法不仅考虑各含水层渗透性差异,而且考虑了抽水井周围水头差对含水层流量的贡献。本文以三维非稳定流理想模型为例,通过对各单元网格的水头和抽水井所处各层流量权重的双重迭代求解,得出非均质承压含水层中各层井流量的分配量。在此基础上,进一步分析不同网格剖分对混合机井各层流量计算的影响及其井水位的校正。     

基于数值模拟的天津市地下水资源均衡分析及压采方案制定

【目的】在深层地下水超采严重地区,分层组进行深层地下水资源均衡分析,合理开发利用地下水资源。【方法】以天津市平原区为研究区,将含水层结构概化成Ⅰ～Ⅴ共5个含水层组,分层组概化边界条件、进行水文地质参数分区,整理源汇项、蒸发量、各含水层组分乡镇开采量和观测孔水位数据,在Visual Modflow平台建立了地下水流数值模型。通过对开采量进行调参、反演,完成模型识别与验证。据此进行深层各层组地下水均衡分析,计算地下水蓄变量,制定了分层组压采方案。【结果】末刻第Ⅱ～Ⅴ含水层组的模拟流场和观测流场分布一致,观测孔模拟水头和实测水头相关系数分别为0.961、0.968、0.951、0.960,典型观测孔动态水位变化过程拟合较好。2013—2015年,深层各层组地下水蓄变量分别为-12 499.3×10~4、-12 055.7×10~4、-9 257.81×10~4m~3,处于超采状态。压采方案下,各含水层组压采量分别为15 862.98×10~4、4 961.24×10~4、1 414.97×10~4、2 469.38×10~4m~3,2020年、2030年深层地下水的蓄变量分别为1.09×108m~3和1.05×108m~3。【结论】模拟结果与天津市深层地下水实际情况相符。     

济宁市黄泛平原区的地下水灌溉

1　黄泛平原区地下水特征山东省济宁市黄泛平原区位于京航运河的西部 ,包括梁山、嘉祥、金乡及鱼台的大部分 ,面积 3 15 1.1ｋｍ2 。由于黄河的多次迁移泛滥 ,沉积了巨厚第四系现代堆积物 ,形成了目前西高微向东倾斜的黄泛平原 ,地面坡降为 1/5 0 0 0～ 1/10 0 0 0。黄泛平原区含水层垂直分布一般分为三层结构 ,即淡咸淡型。目前地下水开发以浅层淡水为主。浅层淡水含水层厚度约为 2 0～ 40ｍ ,以粉砂为主 ,个别有细砂 ,西部较粗 ,近湖较细 ,含水层一般 2～ 3层。在微咸水区的嘉祥仲山、金乡胡集、卜集南洪庙西一带 ,含水层累计厚度不大于 5…     

非均质承压含水层分层并流星及水位估算研究

针对MODFLOW处理承压含水层中混合开采井流量在各层分配上存在的问题,提出了流量权重迭代计算方法.该方法不仅考虑各含水层渗透性差异,而且考虑了抽水井周围水头差对含水层流量的贡献.以三维非稳定流理想模型为例,通过对各单元网格的水头和抽水井所处各层流量权重的双重迭代求解,得出非均质承压含水层中各层井流量的分配量.在此基础上,进一步分析不同网格剖分对混合机井各层流量计算的影响及其井水位的校正.     

应用GMS软件构建三维含水层结构模型

简单介绍了GMS软件的相关功能及构建三维含水层结构模型的方法。以新疆淖毛湖盆地为例,根据地层分布资料、钻孔数据和地面高程数据,通过GMS软件中的2DScatter Point、TINS和Solid模块对地层赋值,建立含水层结构模型。最后提出3个建模中需要注意的问题。     

新疆冲洪积扇区多层结构含水层地下水系统预报模型的比较

冲洪积扇在新疆分布广泛,研究此类结构的地下水预报模型对合理开发利用区域水资源、预防地下水过量开采造成的地质灾害有着重要的理论与实践意义。通过对玛纳斯河流域和阿图什哈拉峻地区水文地质概念模型及数理模型的建立、模型数值求解方法及模型预报精度的对比分析,为建立具有一定预报精度的冲洪积扇区多层结构含水层地下水资源预报模型提供了解决思路及参考依据。     

根据水文地质条件探索电法找水

电法找水的基本原理是依据各种不同地质岩性的电性差异，研究不同的地质结构，找出含水层。具体对地层为石灰岩和白云岩的电法找水进行了详细分析，验证了地质结构和电性解释的吻合性。     

基于数值模拟的地下水开采引起的地面沉降机理和对策研究——以定襄县贾家庄为例

以山西省定襄县贾家庄村抽水引起的地面沉降为例,采用多物理场耦合分析软件Comsol Multiphysics中的多孔弹性接口,基于Boit固结理论,建立抽水区-地面沉降流固耦合模型。通过计算,分析了地面沉降产生的原因,即当水位下降到一定深度后,土中的孔隙水压力降低,由于总压力基本不变,则有效应力相应增大,从而引起土体固结压缩产生地面沉降,并得出了地表变形位移以及含水层水头、土体孔隙水压力分布情况。最后,通过设定不同的开采条件计算工况,给出合理的开采管理建议。     

湿地植物生长对水流特性影响的实验研究

针对云南滇池高原湖泊湿地植物生长种类,采用水槽实验,进行了三种流量、三种不同生长期植物的植物带前、中、后断面沿程流速和垂线流速分布的实验,通过水槽实验研究,分析了植物生长对水流结构影响机理。实验研究表明:①种植物时,植物带前各断面流速比无植物时都有一定的减小,植物对水流有明显的阻滞作用。植物带段过流流速沿程逐渐增加,在一定距离后达到最大值;同一流量条件下,随植物的生长,对水流的阻滞作用越明显,流速变化越大。植物大小一定时,流量越大,植物中流速达到最大值的距离越长。②植物段水流垂线流速分布与明渠恒定流垂线流速分布规律有所不同,植物底部流速比明渠恒定流要小,水面流速比明渠恒定流要大;植物带后水流流态恢复到明渠恒定流流态需要一定的距离。     

Optimal on-farm irrigation scheduling with a seasonal water limit using simulated annealing

As water resources are limited and the demand for agricultural products increases, it becomes increasingly important to use irrigation water optimally. At a farm scale, farmer's have a particularly strong incentive to optimize their irrigation water use when the volume of water available over a season is production limiting. In this situation, a farmer's goal is to maximize farm profit, by adjusting when and where irrigation water is used. However, making the very best decisions about when and where to irrigate is not easy, since these daily decisions require consideration of the entire remaining irrigation season. Future rainfall uncertainty further complicates decisions on when and which crops should be subjected to water stress. This paper presents an innovative on-farm irrigation scheduling decision support method called the Canterbury irrigation scheduler (CIS) that is suitable when seasonal water availability is limited. Previous optimal scheduling methods generally use stochastic dynamic programming, which requires over-simplistic plant models, limiting their practical usefulness. The CIS method improves on previous methods because it accommodates realistic plant models. Future farm profit (the objective function) is calculated using a time-series simulation model of the farm. Different irrigation management strategies are tested using the farm simulation model. The irrigation strategies are defined by a set of decision variables, and the decision variables are optimized using simulated annealing. The result of this optimization is an irrigation strategy that maximizes the expected future farm profit. This process is repeated several times during the irrigation season using the CIS method, and the optimal irrigation strategy is modified and improved using updated climate and soil moisture information. The ability of the CIS method to produce near optimal decisions was demonstrated by a comparison to previous stochastic dynamic programming schedulers. A second case study shows the CIS method can incorporate more realistic farm models than is possible when using stochastic dynamic programming. This case study used the FarmWi$e/APSIM model developed by CSIRO, Australia. Results show that when seasonal water limit is the primary constraint on water availability, the CIS could increase pasture yield revenue in Canterbury (New Zealand) in the order of 10%, compared with scheduling irrigation using current state of the art scheduling practice.     

Characterising rice-based farming systems to identify opportunities for adopting water efficient cultivation methods in Tamil Nadu, India

Efficient water use in rice cultivation is a prerequisite for sustaining food security for the rice consuming population of India. Novel rice production practices, including water-saving techniques, modifications in transplanting, spacing, weeding and nutrient management, have been developed and shown to be effective on farm, but adoption of these techniques by farmers has remained restricted. Potential constraints include technical difficulties with new practices, and labour and gender issues which differ between farms. On the basis of a rapid survey of 100 rice-based farms, four farm types were identified based on their socio-economic and biophysical characteristics. Detailed farm surveys were conducted on three representative farms of each farm type to evaluate land use patterns, use of inputs such as water, labour, nutrient, capital and machinery, income from crop and animal production and off-farm activities. Opportunities exist for one or more new rice cultivation techniques to be adopted in all the four farm types. For all farm types, however, the opportunities for use of water-saving irrigation were the least promising. In general, adoption of water-saving irrigation will not improve farmers’ livelihoods despite its importance in reducing water scarcity problems at regional scale. At farm scale, the potential for adoption of water-saving irrigation depends on the season, location of fields and the irrigation source. Changes in government policies such as rules and regulations, pricing, institution building and infrastructure development, as well as training and education of farmers are needed to improve the adoption of modified methods for rice cultivation.     

Safe and high quality food production using low quality waters and improved irrigation systems and management: SAFIR

The present paper presents the SAFIR project (www.safir4eu.org), which addresses two fundamental problems that over the past decade increasingly have become concerns of the general public: the one problem being the jeopardizing of safety and quality of our food products, while the other being the increasing competition for clean freshwater. The SAFIR project has a multi-disciplinary approach, which integrates the European as well as the global dimension of the EU-policy on food quality and safety. The main driving force behind the project idea is new research results that demonstrated that scheduled uneven irrigation patterns can increase the water use efficiency as well as the quality of vegetable crops. Furthermore, recent innovations in the water treatment and irrigation industry have shown potential for the use of low quality water resources, such as reclaimed water or surface water in peri-urban agriculture, for irrigation of vegetable crops without threaten food safety and quality. The results of SAFIR were achieved from field experiments in Europe and China and modeling activities both at field and farm scale. The present article describes the structure of the project and highlights the main findings and recommendations of the project described in detail in already published papers and in accompanying papers in this special issue.     

对平原地区农业综合开发工作的回顾与思考

滑县地处豫北平原,位于河南省东北部,属黄河冲击平原地区一个典型的农业大县,也是国家级重点贫困县。滑县县委、县政府针对滑县的特殊地理位置以及当地的实际情况,重点从节水灌溉、实施水电等配套措施,彻底改善本地区旱涝不能保收、农机和水电等基础设施落后局面。农业综合开发极大地提高了粮食生产能力．同时．也提升了项目区周边群众对农业开发工作的信心和热情,在全县推进农业现代化进程中很好地发挥了示范、引领作用。     

干旱区农业水资源供需水预测分析及对策研究

针对西北干旱区农业水资源短缺的问题,以新疆洛浦县为例,从作物种植结构调整和灌溉面积变化、灌溉水利用系数提高及灌溉方式改变等方面进行节水分析,并对预测水平年农业供需水平衡进行了预测计算,预测结果表明：现有的灌排工程不能满足农业可持续发展要求;提高灌溉水利用系数势在必行;采用滴灌技术极大地减少了农业用水量,是解决农业供需水矛盾的有效措施。最后,根据预测结果,提出了解决农业水资源短缺、可持续发展的对策,为其他区域水资源的合理开发利用提供有益的参考。     

甘肃景泰提水灌区田间灌水技术评价与改进

通过田间灌溉试验和计算机模拟，对景泰提水灌区现行地面灌水技术进行了评价，研究对比了地面灌溉田间灌水效率的2种计算方法，用模拟地面灌水流运动的计算机模型模拟灌溉试验，得到平均灌水均匀度和田间灌水效率，并针对灌区田间灌水技术存在的问题，提出了改进建议。     

地下水灌溉水质评价的对数型幂函数指数方法

为了科学合理、简便有效地评价灌溉水质,提出了一个灌溉水质评价的指数公式,并采用粒子群算法优化公式中的参数,得出优化后适用于多指标的灌溉水质评价公式.以新疆阿拉尔垦区、尉犁县和宁夏平罗县的水质资料为例进行验证.结果表明,该公式与综合危害系数法、模糊综合评价、突变理论的评价结果基本一致.新疆阿拉尔垦区和宁夏平罗的地下水适合农业灌溉,而尉犁县平原灌区浅层地下水不宜长期直接灌溉.灌溉水质评价公式具有简单便捷的优点,可以快速地得出灌溉水质评价结果,为灌溉水质评价提供了新的有效途径.     

节水灌溉技术中离心水泵的选配

节水灌溉机械化技术是通过合理配套灌溉机械设备,根据作物合理水量要求和土壤渗析速度,维持最佳水分输送速度,减少各种水分损失的机械化灌溉技术.因此,它对节约用水、改变农业生产的条件、抵御自然灾害、确保农作物的高产稳产具有十分重要的作用.在节水灌溉机械化技术中,离心水泵是灌溉机械的重要组成部分.为此,介绍了离心水泵的结构、工作原理、选择依据和选择原则,为促进新疆全面实现农业节水灌溉机械化提供了理论依据.     

Valuing irrigation water using survey-based methods in the Tungabhadra River Basin, India

The paper discusses the challenges in using survey-based methods of economic valuation of water: choice experiments, residual value of water and water trading prices. The three different approaches to economic valuation of irrigation water are compared, all based on data from a farmer survey conducted in two irrigation command areas in the Tungabhadra sub-basin (Karnataka State, India). Prices reported by farmers for sale and purchase of an additional irrigation are of the same order as willingness to pay estimates derived from a choice experiment. Because of small number of water trades there is large variation in market-price based estimates. Financial returns to a given crop as a function of irrigation frequency show values that are both lower (for rice) and higher (for areca nut) than choice experiment estimates. Low convergent validity of different economic valuation methods of irrigation water, is in part due to the large variation in water availability and farm conditions across the watershed, but also because of methodological weaknesses. While recognizing these weaknesses, the paper shows that representative farm surveys using a combination of valuation methods can identify heterogeneity in farm conditions and preferences that may otherwise be overlooked when carrying out irrigation pricing reform.