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941.
淮北平原涝渍兼治的组合排水工程形式   总被引:2,自引:0,他引:2  
由于淮北平原砂姜黑土区的气候、地形、地貌、水文地质、土壤等多方面原因,致使旱、涝、渍频繁,且涝渍灾害往往是紧密相连,先涝后渍,涝渍相随.造成大面积减产.甚至绝收,旱、涝、渍灾害一直困扰着本区的农业发展。通过试验及调查,从治理涝渍效果、提高农业产量、投入产出等方面进行综合分析,提出了几种适宜于本区的组合排水形式。  相似文献   
942.
重点研究了果园施用保水剂后剖面土壤水分动态、果树耗水规律 ,探讨了保水剂作用下土壤水分对果树生长、果实生长发育、产量与品质的影响规律 ,同时对保水剂在山区果园的应用进行了经济可行性分析  相似文献   
943.
Farmers in the Broadview Water District in central Californiahave been improving irrigation practices in response to risingirrigation water prices and reductions in water supply since1989, when incentive policies were first implemented to reducethe volume of subsurface drain water generated in theDistrict. The average salinity of water deliveries hasincreased, over time, as the District has recycled largeamounts of drainage water to achieve regional restrictions ondrainage water discharge. We review irrigation and drainageactivities in Broadview since 1986 with an emphasis on thesustainability of crop production when drainage discharge islimited. Average cotton yields in Broadview have declined inrecent years, both nominally and in comparison with averageyields reported for the large county in which Broadview islocated. Average tomato yields in Broadview have increased inrecent years, but county-wide yields have exceeded Broadviewyields with greater frequency than in the late 1980s. Theseobservations suggest that average crop yields in Broadview maybe starting to reflect the increasing salinity of soil andwater resources, which may be due in part to persistentrestrictions on drainage water discharge.  相似文献   
944.
基于田间实测的地表水流推进过程 ,利用水量平衡法推求波涌灌溉间歇供水条件下的土壤入渗参数。在此基础上 ,利用地面灌溉模型模拟田间水流推进过程并与实测值作对比后发现 ,与单点入渗测试方法相比较 ,该法不仅具有较高的参数估值精度 ,还具备田间试验工作量相对较小、应用简便等特点 ,具有较好的实用价值。  相似文献   
945.
根据广东省台山市都斛镇水稻田控制排灌田间工程试验区的实测资料 ,探讨了在已定工作水头和输水管管径的条件下 ,不同出水口开启状况下各给水栓出流量的数学分析方法 ,同时模拟计算了不同管径 (或改变水头 )条件下给水栓系统运行状态的变化 ,并与实际观测情况进行了比较和分析  相似文献   
946.
高港泵站水利枢纽自动化系统   总被引:1,自引:0,他引:1  
钱福军  杨鹏  蒋步军  陈虹  陆泽群  叶健 《排灌机械》2001,19(5):32-44,38
详细介绍了江苏省泰州引江河高港泵站水利枢纽自动化系统的功能,介绍了系统采用的分布式体系结构、设备分布及其功能分配。  相似文献   
947.
在分析节水灌溉定义内涵的基础上,提出了评价干旱缺水灌区农田节水灌溉的目标标准和技术标准,并对这些评价标准的运用进行了讨论。  相似文献   
948.
The design and management of drainage systems should consider impacts on drainage water quality and receiving streams, as well as on agricultural productivity. Two simulation models that are being developed to predict these impacts are briefly described. DRAINMOD-N uses hydrologic predictions by DRAINMOD, including daily soil water fluxes, in numerical solutions to the advective-dispersive-reactive (ADR) equation to describe movement and fate of NO3-N in shallow water table soils. DRAINMOD- CREAMS links DRAINMOD hydrology with submodels in CREAMS to predict effects of drainage treatment and controlled drainage losses of sediment and agricultural chemicals via surface runoff. The models were applied to analyze effects of drainage intensity on a Portsmouth sandy loam in eastern North Carolina. Depending on surface depressional storage, agricultural production objectives could be satisfied with drain spacings of 40 m or less. Predicted effects of drainage design and management on NO3-N losses were substantial. Increasing drain spacing from 20 m to 40 m reduced predicted NO3-N losses by over 45% for both good and poor surface drainage. Controlled drainage further decreases NO3-N losses. For example, predicted average annual NO3-N losses for a 30 m spacing were reduced 50% by controlled drainage. Splitting the application of nitrogen fertilizer, so that 100 kg/ha is applied at planting and 50 kg/ha is applied 37 days later, reduced average predicted NO3-N losses but by only 5 to 6%. This practice was more effective in years when heavy rainfall occurred directly after planting. In contrast to effects on NO3-N losses, reducing drainage intensity by increasing drain spacing or use of controlled drainage increased predicted losses of sediment and phosphorus (P). These losses were small for relatively flat conditions (0.2% slope), but may be large for even moderate slopes. For example, predicted sediment losses for a 2% slope exceeded 8000 kg/ha for a poorly drained condition (drain spacing of 100 m), but were reduced to 2100 kg/ha for a 20 m spacing. Agricultural production and water quality goals are sometimes in conflict. Our results indicate that simulation modeling can be used to examine the benefits of alternative designs and management strategies, from both production and environmental points-of-view. The utility of this methodology places additional emphasis on the need for field experiments to test the validity of the models over a range of soil, site and climatological conditions.  相似文献   
949.
The use of drainage systems for supplementary irrigation is widespread in The Netherlands. One of the operating policies is to raise the surface water level during the growing season in order to reduce drainage (water conservation) or to create subsurface irrigation. This type of operation is based on practical experience, which can be far from optimal.To obtain better founded operational water management rules a total soil water/surface water model was built. In a case study the effects of using the drainage system in a dual-purpose manner on the arable crop production were simulated with the model. Also, the operational rules for managing this type of dual-purpose drainage systems were derived.The average annual simulated increase in crop transpiration due to water conservation and water supply for subsurface irrigation are 6.0 and 5.4 mm.y–1, respectively. This is equivalent with 520 × 103 and 460 × 103 Dfl.y–1 for the pilot region (2 Dfl 1 US $). The corresponding investments and operational costs are 600 × 103 Dfl and 9 × 103 Dfl.y–1 for water conservation and 3200 × 103 Dfl and 128 × 103 Dfl.y–1 for subsurface irrigation. Hence, water conservation is economically very profitable, whereas subsurface irrigation is less attractive.Comparing the management according to the model with current practice in a water-board during 1983 and 1986 learned that benefits can increase with some 50 and 500 Dfl per ha per year, respectively.  相似文献   
950.
冬小麦叶片水势、气孔阻力、蒸腾速率与环境因素的关系   总被引:1,自引:0,他引:1  
本文依据田间试验资料,分析了冬小麦叶片水势、气孔阻力和蒸腾速率在不同土壤基质势条件下的日变化规律,探讨了其与土壤基质势和天气条件(光照强度、净辐射、饱和差、气温)之间的关系,建立了叶片水势、气孔阻力、蒸腾速率与环境因素间的定量关系式。  相似文献   
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