为了给农田降雨形成的前期高浓度N、P排水径流拦蓄利用从而减少受纳水体污染提供依据,采用小区实验方法,研究了油菜不同生长期植被覆盖度0、22％、49％、79％和100％时,恒定降雨强度4 mm/h条件下,农田排水的变化特征.结果表明:①随着植被覆盖度增加农田初始排水时间明显延迟,同时排水前期20 min排出的流量也随着植被覆盖度的增加而下降.②随着植被盖度的增加,农田排水中各形态N素浓度逐渐增加.③随着植被覆盖度的增加,农田排水中P的浓度随形态不同呈现不同的变化趋势.可溶性磷DP浓度呈上升趋势;PP和TP的平均浓度随着植被覆盖度的增加呈下降趋势.这说明地面覆盖植被可以有效延长农田排水时间,减少农田排水前期的流量,有效减少农田水肥流失.所以增加植被的覆盖度是减少水肥流失的有效方法之一.地面覆盖植被也可以有效减少农田排水中P素的浓度,但无法减少农田排水中N素的浓度,因此在北亚热带湿润气候区的砂壤土区,通过增加植被覆盖度减少农田排水中氮素浓度是不可行的,只有通过施肥方式的改变来实现.

针对南方地区雨水资源充沛的特性,对低层住宅楼雨水资源化利用的可行性和潜力进行分析,提出通过设置屋顶与地面2个水箱进行雨水收集,利用泵管连接2个水箱实现相互补给以供住宅自压冲厕和小区景观利用的方法,从而达到节约能源、充分利用雨水资源和减少城市排涝压力的目的;并以系统利用效率最大为目标,优化了水箱集蓄容积,可为海绵城市建设提供新思路.实例分析了扬州地区不同降雨水平年条件下,该系统每单元户楼顶水箱可自压集蓄利用雨水量60～100m3 ·a-1,节省提水送到楼顶电能平均20 kWh·a-1;楼上与楼下2个集水箱联合调度可集蓄利用雨水总量250 ～310 m3· a-1,也达到减少利用自来水量和减少城镇的排水压力量.由每单元户拦蓄利用雨水资源数量来看,虽数量有限,但推及整个城镇影响将十分巨大.

According to characteristics of irrigation system of low-pressure pipeline,the optimal control area of low-pressure pipeline for facility agriculture was determined at 450~600hm2,basing on the optimizing of pipe network lay out with the optimization of pipe diameter.It would provide scientific basis for the broadscale application and promotion in irrigation system of low-pressure pipeline.

The technology of low pressure pipeline irrigation,as the important choice of current agriculture development,was introduced in this paper.The matters to be attended to were proposed,and the technology was compared with other irrigation project.Results showed there were several advantages and strong adaptability of this technology.It was indicated that the technology of low pressure pipeline irrigation was the primary direction of current agricultural developement,and its popularization and application could promote the development of water saving agriculture and ecological agriculture.

The basic concept and characteristics of ecological river course were expounded,and the insufficiencies in the ecological river course construction were pointed out.Ecological river course construction involves maintaining river course functions,recovering and rebuilding river course ecosystem of ecologically functional areas of the river course.Based on the concept of ecological river course construction,evaluation index system of ecological river course in south China was set up and indexes vividly quantified.This is intended to lay the foundation for ecological river course evaluation and provide direction for ecological river course construction in the region.

Study on the method of quantitative assessment for regional ecosystem is significant in constructing and protecting re-gional ecosystem. The concepts of eco-affecting distance,eco-source and eco-efficacy are led into regional ecosystem assessment for the first time based on the theory of the radioactive resource. The method of quantitative assessment for regional ecosystem is put forward,and the numerical formulas for impact of human disturbance analysis on regional ecosystem is established based on land-scape spatial pattern. The analysis results from the Xinzhuang region in Ganduo Town and Yandang region in Hengjing Town suggest that the method is a valuable uncomplicated tool with concise of conception and intuitional results. It could be widely used for quan-titatively scientific assessing the impact of human disturbance on regional ecosystem.

The method for wetland construction was proposed,i.e.to construct circular expanding section at certain intervals along the beach of two sides of river course with the chord length S and the arc height B at the elevation of 0.5m below the normal water level.The staggered arrangement of the expanding section forms wetlands of wet-dry alternation.In the study,3D numerical calculation and analysis method of turbulent flow was adopted for optimization of the main parameters S and B for the cross-section of wetlands so that the optimal river flow condition could be obtained,and the optimal values S=2.0D and B=0.7D(D: the width of river mouth) for the constructed wetlands were derived from case study.Then,the effects of wetland construction on river flow were analyzed from three aspects,i.e.the flow field of river the course,the cross-section average flow velocity distribution along river course,and the depth-averaged flow velocity distribution in river cross-section.The result shows that wetland construction leads to alternate flow patterns in the whole river course,that the mean flow velocity in cross-section of the wetland section decreases evidently,and that the difference of flow velocity between wetland section and main river channel is significant.

Risks exist in any waterlogging control project due to the random features of natural disasters.The optimization for the regional design criteria for waterlogging control is put forward in this paper based on risk analysis of waterlog losses,and by minimizing the sum of the engineering cost and the super standard waterlog losses as the objective function.In this optimization model,the functional relationship is established between waterlog risks,engineering cost,super standard waterlog losses and decision variable by taking the drainage design criterion P as the decision variable,on the basis of which the design criterion for waterlogging control is optimized.The practical application of the optimization method indicate that the optimized results may be in closer agreement with the regional features and eliminates the arbitray selection of design criterion.

The key indexes commonly used to express characteristics of water-supply performance of water resources system during drought were described,and their applicability for water-supply risk assessment was analyzed.According to the results from research on the real system operation,some valuable conclusions are obtained.It can be briefed that the suitable time-period scale and critical water-demand should be taken for evaluating the reliability of water-supply system;the number of successive water-deficiency periods may be used for analyzing the resilience;expressing the vulnerability of water supply by the water shortage of single time-period is more rational than the total water-deficiency,average water-deficiency and the ratio of total water-deficiency to total water-demand and so on.

From the view point of farmland ecological system, the malpractices of only paying attention to water conservation function without consideration of ecological influences in the construction of irrigation and drainage projects are pointed out. The authors suggest that the planning and construction of irrigation and drainage projects should be harmonious with ecological environment with the prerequisite of good quality farming system in order to ensure sustainable agricultural development.

设施农业阻断了雨水资源的直接利用.本文针对设施农业自身的特点及现状雨水资源利用存在的问题,提出了设施农业雨水资源利用的新思路.通过对设施农业雨水资源化潜力的分析计算,探讨了设施农业雨水资源高效利用的自压灌溉系统设计方法.该系统集开源、节能与节水于一身,具有较强的实用性和众多的优点.

There are a great number of brooks and small lakes in our country,some of which are withering away,thus harmfulness on ecological environment is caused.This phenomenon has not been paid attention to by the local people.In this paper,several reasons which make the brooks and small lakes wither away and harmfulness are set forth to remind the whole society paying attention to the problem and getting along with the natural world in perfect harmony,and avoid unnecessary calamities.