Determination of instantaneous corrosion rates and runoff rates of copper from naturally patinated copper during continuous rain events

Instantaneous corrosion rates of naturally patinated copper of varying age (16 months, 138 and 145 years) have been determined during continuous rain events in the laboratory with electrochemical impedance spectroscopy using a two-electrode cell. The two-electrode cell was found to yield the same information in bulk rainwater as a conventional three-electrode cell.Relatively constant corrosion rates, between 0.2 and 0.6 μm/y, were determined for samples having a two-layer structure with an inner brownish layer of cuprous oxide and an outer greenish layer of basic copper salts (138, 145 years). Samples with cuprous oxide as the dominating phase of the patina (16 months) showed higher and somewhat increasing corrosion rates during a rain event (from 0.6 to 1.2 μm/y). During a continuous rain event, corrosion rates were found to be approximately 10 (brownish patina) and 25 times (greenish patina) lower than corresponding instantaneous runoff rates. The first flush phenomena of the runoff process, with an increased concentration during first flush and a relatively constant concentration during steady state, was indirectly seen as an increase in solution conductivity during the first rain volume followed by relative constant value. The contribution of the concentration in the first flush to the total annual runoff rate was significant for panels having a greenish layer (138, 145 years) whereas it was negligible for panels having a brownish layer (16 months).     

Investigation of Boundary Shear Stress and Pollutant Detachment from Impervious Surface during Simulated Urban Storm Runoff

Pollutant detachment rates have been determined for four chloride salts during simulated urban storm runoff. Under rainfall and/or overland flow conditions, chloride mass flux was measured and related to boundary shear stress of the test surface. Washoff coefficients, presumed to depend only on pollutant characteristics, were computed based on the slopes of dimensionless mass flux versus dimensionless time plots. Washoff coefficients were found to vary among and between the chloride compounds studied. In general, higher overland flow rates produced lower boundary shear and lower washoff coefficients. The combination of simulated rainfall and overland flow resulted in an increased boundary shear and an increased washoff coefficient. An empirical washoff coefficient based on a load characteristic curve derived from an exponential washoff relationship was also computed from the runoff data and compared with the previous washoff coefficient. A linear correlation between these two washoff coefficients was observed. The magnitude of the latter coefficient under simulated rainfall was consistent with reported values obtained from field data.     

A comprehensive approach to evaluating watershed models for predicting river flow regimes critical to downstream ecosystem services

Selection of strategies that help reduce riverine inputs requires numerical models that accurately quantify hydrologic processes. While numerous models exist, information on how to evaluate and select the most robust models is limited. Toward this end, we developed a comprehensive approach that helps evaluate watershed models in their ability to simulate flow regimes critical to downstream ecosystem services. We demonstrated the method using the Soil and Water Assessment Tool (SWAT), the Hydrological Simulation Program–FORTRAN (HSPF) model, and Distributed Large Basin Runoff Model (DLBRM) applied to the Maumee River Basin (USA). The approach helped in identifying that each model simulated flows within acceptable ranges. However, each was limited in its ability to simulate flows triggered by extreme weather events, owing to algorithms not being optimized for such events and mismatched physiographic watershed conditions. Ultimately, we found HSPF to best predict river flow, whereas SWAT offered the most flexibility for evaluating agricultural management practices.     

朱庄水库流域径流量变化特征及影响因素

利用朱庄区域长系列水文资料,对径流量的年内、年际变化特征及变化趋势进行了分析研究,分析了人类活动影响引起下垫面变化导致径流变化的原因,估算了降水和下垫面变化对径流量的影响量。该区域径流量年内、年际变化较大;多年径流量系列呈减少趋势,尤其从20世纪70年代末以来径流量发生了显著变异;下垫面变化是径流量减少的主要原因。     

安太堡露天矿排土场表层岩土的径流特征与复垦种植

采用针孔或小型人工降雨机，分别模拟山西塞北高原９０～６０ｍｉｎ、６０～４５ｍｉｎ、４５～３０ｍｉｎ、３０～１５ｍｉｎ各时段降水量极大值，探讨大型露天矿排土场各种排土工艺下地表岩土的径流特征，以指导排土工艺和复垦种植。     

Runoff Analysis for a Small Watershed of Tono Area Japan by Back Propagation Artificial Neural Network with Seasonal Data

The rainfall runoff (R-R) process was studied for two small sub-basins having different sizes in a mountainous catchment of Tono area Japan. The runoff and other meterological data have been collected in this catchment for the last 14 years. The major objective of this study was to construct numerical models for these sub-basins to predict runoff after 1/2 and 1 h. The effects of season and the size of the catchment on R-R process were also investigated. The hydrogeological conditions of the catchment were studied prior to the analyses. The data obtained for summer (rainy) and winter (dry) seasons were treated separately in order to study the seasonal effects on the model development. The back propagation artificial neural network technique (BPANN) and the multivariate autoregressive and moving average models (ARMA) were adopted for the analysis. It was found that for very small catchments the seasonal effects are dominant and therefore separate models should be developed for each season to obtain better forecasting estimates. It was also found that the predictions by BPANN models were better than multivariate ARMA models for intense rains having complex R-R relationships in summer. On the other hand, both the modelling techniques yielded almost similar results for smaller rains in winter. It was also found clearly that the accuracy of prediction decreased with the increase of the time period for prediction.     

降雨径流系列的一致性分析

降雨径流关系是否发生变化，即不同时期降雨径流关系有无显著差异是一个生产中迫切需要解决的问题。本文以山西省榆社县云簇水库降雨径流系列为例，进行了降雨径流特性的分析，内容包括降雨径流双累积曲线的特性分析、年径流系数的变化过程分析、秩和检验、回归方程的差异分析等。得出云簇水库在１９７９年以前与以后，虽年径流深、年径流系数有差异，但降雨径流关系并无明显差异的结论。     

汾河中下游“96.8”洪水灾害成因分析及防洪对策

１９９６年８月，汾河中下游发生了严重洪涝灾害，鉴于此次洪水范围广、历时长、洪灾严重等特点，为探求其致灾原因和存在的问题，同时也为今后整个流域的规划和治理提供一些依据。在１９９７年初，省水利厅以晋水发［１９９７］２６７号文件下达了研究任务。本文即是针对汾河中下游“９６．８”洪水的产生原因、致灾因素，以汾河干流为主，考虑主要产洪支流文峪河、潇河等，在对汾河水库到汾河入黄口进行全流域性实地调查研究的基础上，对该流域水利工程防洪效益进行分析，通过分析干流及区间洪水，计算出干流区间及主要支流径流系数，同时估算了干流各段河道行洪能力，对现有河道及堤防工程存在的问题提出了治理建议。     

Impact of Storm-Water Runoff on Clogging and Fecal Bacteria Reduction in Sand Columns

Storm-water runoff has been identified as a major cause of coastal water quality degradation. Storm-water outfalls, common in many coastal towns, convey bacteria and other pollutants into the ocean and estuaries. In an effort to minimize this impact, the Town of Kure Beach, North Carolina, installed Dune Infiltration Systems (DIS) at two storm-water outfalls to receive storm-water runoff and allow infiltration beneath the beach dunes. A laboratory column experiment was performed to supplement this installation and determine the potential hydraulic and bacterial removal efficiency of the sand comprising the Kure Beach dunes. Columns constructed using sand collected at different depths of the dune were used to analyze the affect of bacteria application on infiltration and to examine the changes in bacteria removal that occur as infiltration rates are affected by bacteria-laden water application. Sand columns were loaded over a 60-day period with either bacteria-free storm water or storm water spiked with Escherichia coli. The seepage rate for the bacteria-spiked storm-water treatment was significantly lower (p<0.05) than the seepage rate of the bacteria-free treatment, particularly toward the end of the study. Bacteria application likely compounds the impact of sediment clogging at the sand/storm-water interface. This study indicates the need for maintenance when implementing a DIS or similar sand filter to maintain design infiltration rates, especially if reduced infiltration rates are not planned for in the design. However, a decrease in seepage rate was correlated with a decrease in effluent bacteria concentration in the bacteria-spiked storm-water sand columns. Thus, optimization is required to provide maximum infiltration of storm-water while maintaining bacteria removal efficiency.     

Review of Bioretention System Research and Design: Past, Present, and Future

This paper reviews the evolution of bioretention systems, a promising at-source storm-water best management practice. The introduction of bioretention systems in the 1990s by Prince George’s County, Md. is examined along with the motivations behind the development of the systems. A summary of the research findings on the performance of bioretention systems is provided including proposed design modifications to improve the field performance. Also included is an overview of past and current bioretention design guidelines in North America, as well as a discussion of issues surrounding the public adoption and implementation of bioretention systems. Potential alternative uses for the systems are highlighted and a review of bioretention modeling work is provided. Finally, the paper outlines research needs and anticipated future work necessary to bring about the widespread use of bioretention systems.