Characterizing Storm Hydrograph Rise and Fall Dynamics With Stream Stage Data1

Abstract: Storm‐flow transients (i.e., hydrograph rise and fall dynamics) may represent an important aspect of understanding streamflow dynamics. However, little is known about how temporal resolution of transient data and climate variability may color these potential indicators of hydrologic pattern or condition. Warm‐season stream stage and rainfall were monitored continuously (5 min) during the 2002 water year in eight tributaries of the Little Miami River (Ohio), which drain 17‐58 km² catchments. Rise rates generated using 5‐min data were different than those generated with mean daily data [calculated with the Indicators of Hydrologic Alteration (IHA) software], though fall rates were similar for fine and coarse temporal data. This result suggests that data with low temporal resolution may not be adequate to fully represent the dynamics of storm rise rates. Conversely, fall rates based on daily stage data (via IHA) were similar to those based on the 5‐min data, and so daily mean data may be appropriate for characterizing fall rates. We next analyzed the possible correlations between rainfall variability and storm‐flow stage dynamics. We derived rise and recession rates from storm stage hydrographs by assuming exponential rise and decay of a runoff peak. We found that raw rise rates (R_raw) were correlated with both the maximum rainfall rate and the time to the centroid of a rain event. We subsequently removed the trend based on these rainfall characteristics, which yielded new representations of rise rates abbreviated as R_rate and R_tcent, respectively, and that had lower variability than the uncorrected (raw) data. Fall rates were found to be independent of rainfall characteristics. Due to the predominant influence of stream hydrology upon aquatic biota and nutrient fluxes, our work suggests that these stage data analysis protocols can refine or otherwise reduce variability in these indices by accounting for relevant factors such as rainfall forcing. These protocols for derivation of transient indices should be tested for their potential to improve correlations between stream hydrology and temporally aligned biotic data and dissolved nutrient fluxes in streams.     

人为泥石流起动及产沙放水冲刷实验——以神府-东胜矿区为例

神府东胜矿区位于黄土高原北部干旱半旱过度地带。由于煤田的大量开采,诱发了大量的环境问题,尤以人为泥石流最为严重,本文以神府－东胜矿区人为泥石流为研究对象,采用人工放水冲刷模拟的方法,分析了坡面型和沟谷型泥石流源地松散体起动、产沙、泥石流过程的特性,所得结论为：（１）放水历时长,强度大,有利于泥石流的形成;（２）弃土石渣起动,是该区泥石流固体物质的主体;（３）沟道型泥石流放水冲刷模拟实验,便于观测石     

暴雨泥石流预报程式

论述了暴雨泥石流预报的４个基本原理,即现象可预报性原理、成困分类组合原理、判别因素简化原理和预报决策依据原理。对泥石流时间预报模型作了分类,提出了通过泥石流活动周期与降水量周期叠加,建立泥石流活动性的长期趋势预测模型;通过泥石流活动年数频次与降水量丰欠等级频次组合,建立泥石流活动年份频次的态势预测模型;根据月或旬雨量确定泥石流发生的阈值关系,建立年内月或旬泥石流发生频次的中期预报模型;由短期天气预     

阵性泥石流运动与堆积的欧拉─拉格朗日模型──Ⅰ.理论

自然界中的泥石流具有突发性和非恒定性的特点。为了模拟典型泥石流现象,在流团模型的 基础上,进一步完善了基于欧拉─拉格朗日（Ｅ—Ｌ）观点的ＰＩＣ（Ｐａｒｃｅｌ　Ｉｎ　Ｃｅｌｌ）算法,细化了流元结 构,建立了能够模拟典型阵性泥石流发生、运动和堆积的准结构两相流模型。求解该模型不仅可以 模拟泥石流运动过程,而且可以对泥石流的堆积过程、停积形态、冲刷特征及泥石流中多组分颗粒 的分选特征进行定量描述。     

电子产品野外环境下温循加速载荷谱编制方法

目的 将电子产品在野外环境下日变化波动与季节差异明显的温度载荷编制成温循载荷谱和转换为加速载荷谱。方法 通过四点雨流计数法提取原谱中的载荷循环信息,对提取的循环信息进行分布拟合、相关性检验等统计分析,进而构建循环均值与范围值的联合概率密度函数,再运用概率密度法,编制出8×8二维环境载荷谱。在二维载荷谱基础上,编制出温循载荷谱,使用针对电子部件参数修正的加速方程转化为加速载荷谱。结果 利用野外作业现场1个作业周期内的气温纪录,提供了一套编制温循载荷谱和转换加速载荷谱的合理化流程和解决方案。结论 该制谱方法可以利用原始环境谱中绝大部分有效信息,较好地还原电子部件野外作业阶段经历的温度变化过程,为电子产品的加速寿命试验和使用寿命预测奠定基础。     

基于SPH方法与GPU并行计算的复杂阶梯流数值模拟

为了更有效地模拟和分析地铁站内复杂楼梯上洪水流动的动力学特征,采用光滑粒子流体动力学方法(SPH)并借助GPU并行计算技术对复杂形态(带1、2、3个休息平台的直行、直角转弯L型)阶梯上洪水流动特征和漫延过程进行数值建模和计算分析。基于SPH方法和GPU并行加速的复杂阶梯流模型的数值模拟结果表明:该模型不但可以计算获得更好的阶梯流流态,而且具有较高的计算效率;不同休息平台数、不同形态阶梯上洪水水流呈现差别较大的水流特征;该模型借助GPU并行加速,适合研究大尺度复杂楼梯上洪水漫延问题,可为分析和评估洪水水流对地铁站楼梯上被困人员疏散过程的影响提供有力的工具。     

油气田建设项目施工期环境监理探析

针对油气田建设项目的具体情况,对油气田建设项目施工期主要环境影响,包括钻井作业、输气站及输气管道建设工程中的主要环境影响进行了分析,从施工期的污染防治措施监理、生态保护措施监理、环境保护设施监理几个方面对施工期环境监理的主要内容进行了探讨。     

Impacts of Urbanization on Stream Habitat and Fish Across Multiple Spatial Scales

We analyzed the relation of the amount and spatial pattern of land cover with stream fish communities, in-stream habitat, and baseflow in 47 small southeastern Wisconsin, USA, watersheds encompassing a gradient of predominantly agricultural to predominantly urban land uses. The amount of connected impervious surface in the watershed was the best measure of urbanization for predicting fish density, species richness, diversity, and index of biotic integrity (IBI) score; bank erosion; and base flow. However, connected imperviousness was not significantly correlated with overall habitat quality for fish. Nonlinear models were developed using quantile regression to predict the maximum possible number of fish species, IBI score, and base flow for a given level of imperviousness. At watershed connected imperviousness levels less than about 8%, all three variables could have high values, whereas at connected imperviousness levels greater than 12% their values were inevitably low. Connected imperviousness levels between 8 and 12% represented a threshold region where minor changes in urbanization could result in major changes in stream condition. In a spatial analysis, connected imperviousness within a 50-m buffer along the stream or within a 1.6-km radius upstream of the sampling site had more influence on stream fish and base flow than did comparable amounts of imperviousness further away. Our results suggest that urban development that minimizes amount of connected impervious surface and establishes undeveloped buffer areas along streams should have less impact than conventional types of development.     

都江堰市红色村干沟泥石流活动特征及危险性评估

"5·12"四川汶川大地震导致灾区地质灾害危险性大大增强,严重影响了周边居民的生命财产安全。都江堰市虹口乡红色干沟泥石流灾害隐患点是其中之一。根据泥石流的成因、类型、规模,以及泥石流的活动特征,对泥石流活动进行了危险性评估,指出泥石流防治工程方案应采用以排为主,适当拦挡的原则,建拦挡坝用以消能、调节泥石流流量;建防护堤用以限制泥石流漫流,对居民区进行有效防护。