In recent years , such problems as the extension and application of on - film irrigation , reclamation of salinized soils , and prevention of secondary salinization have made it important to study coupled movement of soil water , salt and heat transfer under plastic mulch in arid and semi - arid areas 近年来覆膜灌溉的推广应用、盐碱地开发和改良以及土壤次生盐碱化防治等问题使得研究西北干旱-半干旱地区覆膜条件下土壤水、盐、热耦合迁移规律成为重要课题。
After the 1990 ' s , dryness index increase especially in east of shandong peninsula and north of yellow river ; east of shandong peninsula , most of south - east shandong and south shandong are from humid to semi - humid , the areas to the north of yellow river is from semi - humid to semi - arid than that of the year from 1961 to 1976 进人90年代以后，与1961 - 1976年相比，干燥度指数普遍增大，半岛东部及黄河以北地区干燥程度增大得最为明显，半岛东部、鲁东南及鲁南的大部分地区由湿润区演变成了半湿润区，而黄河以北绝大部分地区及鲁中北部、半岛西北部的局部地区则由半湿润区演变成了半干旱地区。
The dual missions of the laboratory are to develop irrigation and drainage water management practices and methods that use water efficiently , improve agricultural productivity and sustainability , and reduce negative environmental impacts of irrigated agriculture in semi - arid and arid areas ; and to develop chemical and non - chemical alternatives to soil fumigation with methyl bromide 其宗旨的是发展灌溉排水管理的实践和方法模型，有效用水，促进农业的多产和高效，降低灌溉农业中干旱地区和半干旱地区的灌溉农业对环境的不良影响，发展无化学的甲基溴化物替换技术。
Therefore , metals moving upwards from mineralizations may be absorbed and form weak geochemical anomalies ( weak signals ) in surface loess . the metals can be effectively extracted by neutral salt . loess - covered area in china is primarily distributed at the semiarid region , the secondary carbonates , which were formed after precipitation of ions through evaporation and capillary processes , are widespread in the surface soil 黄土覆盖区主要分布在干旱半干旱地区，次生碳酸盐在地表土壤中普遍存在，蒸发所产生的毛细作用、地气流的上升作用等所带入的各种形式金属元素，在地表土壤(黄土)与碳酸盐发生共沉淀或被吸持。
The space - time distribution of chinese semi - ari d region surface water is n ' t even , the differences in a year are obvious ; the differences of underground water between years are not so obvious as surface water , but it still has a decreasing tendency , especially in shanxi and sha ' anxi provinces . there is a significant linear correlation between the precipitation and water resources in semi - arid region , the dynamic regularity of water resources is basically same as the dynamic regularity of precipitation 半干旱地区地表水资源时空分布不均匀，年内分配差别大，地下水资源年际间变化率不大，但总体有减少的趋势，尤以陕西和山西突出。半干旱地区降水量与水资源量线性相关显著，降水量的变化规律基本上与水资源量的变化规律吻合。
To overcome the restriction of water and heat on agricultural production in northwestern arid and semiarid region , the farming practice of clear plastic film mulch was spread due to its capacity of retaining water and temperature in the winter wheat field in many areas , howeve r soil properties had also were affected significantly in the meantime 在西北干旱半干旱地区，为了克服水热资源对农业生产的限制，地膜覆盖的农作措施以其显著的增温保墒作用在冬小麦农田得到了大面积的推广和应用；与此同时，该农作措施下的土壤性质也发生了深刻的变化。
They have great potentialities to ecological restoration and high value to being used as forage . however researches on their physiological characteristics related to drought adaptabilities were not sufficient , yet . therefore , it is necessary to reveal more properties in order to increase efficiency in the ecological practice and to promote using in pasturage 驼绒藜属( ceratoides )植物为干旱、半干旱地区具有重要生态价值和饲用价值的旱生半灌木资源，对该属植物适应干旱生理特性的研究尚不充分，加深研究有助于提高对它们的利用效率和应用价值。
The industrialized manufacturing of this product plays an important role in grain crops drought - fight and abundant harvest ensuring in arid and semiarid region , drought - fight and yield increasing of fruits and vegetables , fresh keeping of flowers , municipal gardening , forest drought - fight , drought degeneration reduction of pasture ecology , and desert vegetation protection , etc 该产品的产业化生产，对干旱、半干旱地区粮食作物抗旱保丰收、果树蔬菜抗旱增产、鲜花花卉保鲜、城市园艺绿化、林树抗旱、减少牧草生态因旱退化、沙漠植被保护等方面有着重要应用。
To this area precipitation materials for many years , evaporate materials , surface flow materials , hydrometeorological materials , hydrogeological materials carry on exhaustive analysis , have analysed the state of water resource of the sand district , proceed from the heat of the earth ' s surface is balanced , water yield balanced basic theories , combine the amount of regional water resource set up of the materials , such as scene , hydrology , soil of the sand district , etc . and estimate models , have calculated the surface water , groundwater of this area , has carried on models to examine according to the real data , and has predicted to the state of water resource under different climate change scenes of future that analyse . have put forward the scheme that the water resource in this area utilized rationally , use the non - linear motive force model to predict the precipitation , utilize the materials of actual observation , the natural supply amount of calculating out groundwater of sand ground of balanced principle of the amount of water used at the same time , and can exploiting amount predict to groundwater , district of sand , 本文以宁夏半干旱地区盐池县沙地水资源为研究对象，对该地区多年降水资料、蒸发资料、径流资料、水文气象资料、水文地质资料进行了详尽的分析，分析了沙区的水资源状况，从地表热量平衡、水量平衡的基本理论出发，结合沙区的气象、水文、土壤等资料建立了区域水资源量估算模型，计算了该地区的地表水、地下水，根据实际资料进行了模型检验，并对未来不同气候变化情景下的水资源状况进行了预测分析，提出了该地区水资源合理利用的方案，运用非线性动力模型对降水量进行预测，同时利用实际观测资料，运用水量平衡原理计算出沙地地下水的天然补给量，并对沙区地下水可开采量进行预测。
