降雨-蒸发与地下水耦合作用下的大型尾矿库重金属Cu2+迁移数值模拟分析

为考虑降雨-蒸发与地下水耦合作用对尾矿坝重金属迁移的影响,以本钢集团歪头山铁矿尾矿库作为工程背景,应用Geostudio软件,选择SEEP/W、VADOSE/W和CTRAN/W模块,模拟降雨和蒸发作用下的尾矿库地下水的渗流特性及重金属污染物的迁移规律.结果表明,降雨-蒸发作用对尾矿库表层土壤的孔隙水压力有影响,深层土壤...     

基于无线传感网的水雨情监测节点设计关键技术研究

及时准确采集和传输信息是水雨情监测系统的基本要求.文章分析了当前水文站点对水雨情的监测技术现状,随着无线传感器网络(WSN)的应用和普及,提出了在复杂环境下建立水雨情无线传感器网络的必要性,并对组建的网络节点硬件设计和节点定位问题做了分析和研究.     

代表单元尺度概念及其在洋河流域控制雨量站布设中的应用

本文首次提出代表单元尺度概念及其协同学意义，在划分子单元规模时，大于代表单元尺度的子区域之间相互独立，而小于该尺度的子区域之间彼此空间结构相关，在小于ＲＥＬ的尺度上研究问题时，必须考虑区域内各量的空间结构，不能用简单的平均方法以点代面，对大于ＲＥＬ的尺度上研究时，由于子区域间相互独立，可以考虑用算术或权重平均以点及观，可应用半方差理论确定代表单元尺度，最后应用代表单元尺度概念分析了河北省洋河流域遥     

Monitoring of Cryptosporidium and Giardia river contamination in Paris area

This study evaluates the protozoan contamination of river waters, which are used for drinking water in Paris and its surrounding area (about 615,000 m(3) per day in total, including 300,000 m(3) for Paris area). Twenty litre samples of Seine and Marne Rivers were collected over 30 months and analyzed for Cryptosporidium oocysts and Giardia cysts detection according to standard national or international methods. Cryptosporidium oocysts and Giardia cysts were found, respectively, in 45.7% and 93.8% of a total of 162 river samples, with occasional high concentration peaks. A significant seasonal pattern was observed, with positive samples for Cryptosporidium more frequent in autumn than spring, summer and winter, and positive samples for Giardia less frequent in summer. Counts of enterococci and rainfalls were significantly associated with Giardia concentration but not Cryptosporidium. Other faecal bacteria were not correlated with monitored protozoan. Marne seems to contribute mainly to the parasitic contamination observed in Seine. Based on seasonal pattern and rainfall correlation, we hypothesize that the origin of contamination is agricultural practices and possible dysfunction of sewage treatment plants during periods of heavy rainfalls. High concentrations of protozoa found at the entry of drinking water plants justify the use of efficient water treatment methods. Treatment performances must be regularly monitored to ensure efficient disinfection according to the French regulations.     

Selection of Superior Tillage and Fertilizer Practices Based on Rainfall and Soil Moisture Effects on Pearl Millet Yield under Semiarid Inceptisols

Based on seven field experiments of pearl millet with nine treatment combinations of tillage and fertilizer nutrients conducted during 2000–2006 in a semiarid inceptisol at Agra, an assessment is made in this paper about sustainability of treatments using rainfall received during the crop growing period and available soil moisture at sowing, 20, 40, and 60?days after sowing (DAS) and harvest. Three practices, each of tillage: conventional tillage+mechanical weed control, low tillage+mechanical weed control, and low tillage+mechanical weed control+herbicide; and fertilizer application of 60?kg?N [farm?yard?manure?(FYM)]+40?kg?P/ha, 30?kg?N (FYM)+30?kg?N (urea)+40?kg?P/ha and 60?kg?N (urea)+40?kg?P/ha were tested in the same site over seven years. The F-test indicated significant soil moisture differences on different DAS and also between different tillage treatments. Significant yield differences were found among treatments of tillage and fertilizer and their interaction in all seasons, except 2001 and 2002. Treatment-wise correlation of yield with monthly rainfall received in June–September and available soil moisture on different DAS indicated that September rainfall had a negative and significant correlation with yield attained by tillage and fertilizer treatments. The soil moisture at 20 DAS had a negative and significant correlation with yield under all treatments except conventional tillage+mechanical weed control. The soil moisture at 60 DAS and harvest had a positive and significant correlation with yield attained under different tillage and fertilizer treatments. Regression models of yield were calibrated for tillage and fertilizer treatments through monthly rainfall during July–September and soil moisture on different DAS. The predictability of yield improved significantly by inclusion of both rainfall and soil moisture variables in the models compared to either of the two groups of variables. Ranks were assigned to tillage and fertilizer treatments for yield attained in individual years and mean yield, prediction error, and sustainable yield index over years. The study indicated that conventional tillage+mechanical weed control among tillage together with 30?kg?N (FYM)+30?kg?N (urea)+40?kg?P/ha was superior with a minimum rank sum compared to other treatments. The treatment gave a maximum sustainable yield of 1,683?kg/ha with a net return of Rs 5,670?ha, benefit–cost ratio of 1.16, and sustainable yield index of 47.2% under semiarid inceptisols of Agra.     

Impact of New Rainfall Patterns on Detention Pond Design

A new set of dimensionless rainfall hyetographs has been developed for the state of South Carolina. The new hyetographs show trends similar to those developed recently in other states and in general have milder intensities and lower peak rainfall than the Soil Conservation Service (SCS) rainfall hyetographs. This paper evaluates the impact the new hyetographs have on rainfall runoff and detention pond design and compares the results with those using the SCS hyetographs. Peak discharges for basin runoff were reduced up to approximately 20% of the predicted peak runoff rate using the current SCS hyetographs. Detention pond peak stage was also reduced by 25–50% of the predicted SCS stage. This analysis suggests that design hyetographs should be regularly updated to incorporate recent rainfall data.     

温室效应对淡水生态系统的影响

近一个世纪以来,温室效应一直是困扰人类的一大环境问题.温室效应引起全球变暖,淡水生态系统也受到影响.温室效应加剧引起水温升高、水中含氧量下降、水体富营养化加速和水生生物多样性减少,造成全球降水量重新分配,旱涝灾害发生频繁,江河湖泊的水量发生改变.控制温室效应最根本的途径是减少温室气体的排放.     

Optimal Instantaneous Unit Hydrograph from Multistorm Data

An optimization method for estimating an optimal smooth instantaneous unit hydrograph (IUH) from multistorm data taken simultaneously is proposed. A gamma IUH is used for representing the analytical IUH. The parameters of the analytical IUH are optimized. The method avoids oscillations in the tail end of IUH. It automatically takes care of the volume and nonnegativity constraints. The application of the method is illustrated through examples. The new method reliably estimates the optimal IUH.     

Integrated Two-Dimensional Surface and Three-Dimensional Subsurface Contaminant Transport Model Considering Soil Erosion and Sorption

To investigate the complex hydrological, morphodynamic, and environmental processes in watersheds, a physically-based integrated two-dimensional (2D) surface and three-dimensional (3D) subsurface model for flow, soil erosion and transport, and contaminant transport in the surface-subsurface system is presented in this paper. The model simulates the rainfall-induced surface flow by solving the depth-averaged 2D diffusion wave equation and the variably-saturated subsurface flow by solving the 3D mixed-form Richards equation. The surface and subsurface flow equations are coupled using the continuity conditions of pressure and exchange flux at the ground surface. The model uses the concept of nonequilibrium in the depth-averaged 2D simulation of nonuniform total-load sediment transport in upland fields, considering detachments by rainsplash and hydraulic erosion driven by surface flow. The integrated 2D surface and 3D subsurface contaminant transport model takes into account the contaminant changes due to sediment sorption and desorption, as well as exchanges between surface and subsurface domains due to infiltration, diffusion, and bed change. The model applies the same set of surface equations of flow, sediment, and contaminant transport for describing both upland areas and streams, so that no special treatments are required at their interface. The established model has been evaluated by comparisons with published experimental, numerical, and analytical data and then applied in an agricultural watershed. The model is suitable for wetland areas and agricultural watersheds in which streams are not very narrow and deep, and meanwhile a relatively fine mesh that can distinguish the streams is preferred.     

Effects of urban grass coverage on rainfall-induced runoff in Xi'an loess region in China

In this study, laboratory rainfall simulation experiments were conducted to investigate the regulatory effects of grass coverage on rainfall-runoff processes. A total of 80 grass blocks planted with well-grown manilagrass, together with their root systems, were sampled from an eastern suburban area of Xi'an City in the northwest arid area of China and sent to a laboratory for rainfall simulation experiments. The runoff and infiltration processes of a slope with different grass coverage ratios and vegetation patterns were analyzed. The results show that the runoff coefficient decreases with the increase of the grass coverage ratio, and the influence of grass coverage on the reduction of runoff shows a high degree of spatial variation. At a constant grass coverage ratio, as the area of grass coverage moves downward, the runoff coefficient, total runoff, and flood peak discharge gradually decrease, and the flood peak occurs later. With the increase of the grass coverage ratio, the flood peak discharge gradually decreases, and the flood peak occurs later as well. In conclusion, a high grass coverage ratio with the area of grass coverage located at the lower part of the slope will lead to satisfactory regulatory effects on rainfall-induced runoff.