基于DEM和SCS模型的吉泰盆地红壤丘陵区径流模拟

为研究吉泰盆地红壤丘陵区降雨-径流关系变化,建立吉泰盆地红壤丘陵区坡地径流资源潜力公式,探究坡地径流资源化可行性.采用泰和水保站12个不同覆被下径流小区的观测数据,通过以该流域部分实测次降雨-径流过程进行模型参数率定,用算术平均值法求出研究区CN值,并用部分降雨—径流资料进行模拟验证,得出符合该流域的SCS模型.结果表明:模型对吉泰盆地红壤丘陵区合格率为65％ ～ 85％,且不同覆被下径流小区模拟结果存在明显差异,植被覆盖度高的产流量小,反之产流量相对偏高.通过对结果的分析,发现降雨量越大,模拟效果越好,准确性越高.     

Simulations of storm hydrographs in a mixed-landuse watershed using a modified TR-20 model

Most flood damage in Korea is caused by heavy rainfall events and typhoons during the summer rainy season. A modified Natural Resources Conservation Service (NRCS) TR-20 model, TR-20-RICE, was developed to investigate the storm runoff characteristics of a 385-ha mixed-landuse watershed in Korea. The TR-20-RICE not only used the rainfall excess and hydrologic flood routing components of the original TR-20 model, but also included a paddy runoff process, which captured irrigated paddy runoff characteristics such as inundation, retention storage, and surface runoff. The performances of TR-20 and TR-20-RICE were compared using storm hydrographs and observational data. The results indicated that both models simulated storm runoff accurately over the simulation period. The TR-20-RICE runoff volume, peak discharge, and time-to-peak predictions were slightly closer to observations than those of the TR-20. The TR-20-RICE model may an effective alternative to the TR-20 model for generating storm hydrographs, particularly in the mixed-landuse watershed in Korea.     

Comparative evaluation of SCS-CN-inspired models in applications to classified datasets

One of the popular methods for estimating the depth of surface runoff for a given rainfall event is the Soil Conservation Service Curve Number (SCS-CN) method. Of late, several inconsistencies in its soil moisture accounting procedure have been pointed out by Michel et al. (2005), and a more rational procedure suggested. Recently, a modification incorporating an expression for estimation of initial soil moisture store level, a crucial parameter, was suggested by Sahu et al. (2007). The present study compares this modification with the original SCS-CN model and the other available variants on a large set of data of 76 small agricultural watersheds of the United States and finally suggests an improved model. The comprehensive comparison between these models reveals the proposed improvement to perform better than all other versions in all classified applications based on land use, soil type, combinations of land use and soil type, and precipitation regimes. A simplified version of the model is further suggested for practical applications.     

基于模块神经网络的非线性降雨径流模拟研究

针对流域水文系统的复杂性和非线性,利用人工神经网络(ANN)建立了一种混合非线性模型来精确模拟降雨径流。针对一般人工神经网络存在不能有效地处理先验知识和其他来源数据、处理较大数据集时耗时长、CPU消耗高以及处理较小数据集时精度低等问题,在多层感知器(MLP)的基础上引入模块神经网络(MNN)。模块神经网络具有独立的拓扑结构,可以有效地处理降雨径流中具有复杂空间关系的参数。结果表明,对比人工神经网络,模块神经网络模拟降雨径流耗时更短,精度更高。     

流域降雨径流关系的变化现状及其原因分析

通过分析总结我国流域降雨径流关系的变化现状,结合国内外研究流域降雨径流关系的方法,从宏观上阐述引起这种变化的原因,认为造成流域降雨径流关系变化的主要原因是大量的人类活动。     

Using elevation to aid the geostatistical mapping of rainfall erosivity

This paper addresses the issue of incorporating a digital elevation model into the mapping of annual and monthly erosivity values in the Algarve region (Portugal). Besides linear regression of erosivity against elevation, three geostatistical algorithms are introduced: simple kriging with varying local means (SKlm), kriging with an external drift (KED) and colocated cokriging. Cross validation indicates that the straightforward linear regression, which ignores the information provided by neighboring climatic stations, yields the largest prediction errors in most situations. Smaller prediction errors are produced by SKlm and KED that both use elevation to inform on the local mean of erosivity; kriging with an external drift allows one to assess the relation between the two variables within each kriging search neighborhood instead of globally as for simple kriging with varying local means. The best results are generally obtained using cokriging that incorporates the secondary information directly into the computation of the erosivity estimate. The trade-off cost is the inference and modeling of three direct and cross semivariograms.     

Numerical calculation of secondary discharge peak from a small watershed using a physically based watershed scale infiltration simulation

Numerical infiltration simulations were performed to reproduce secondary discharge peaks in a mountainous forest watershed (watershed area, 1.89 ha; average topsoil depth, 2.61 m; and bedrock geology, Mesozoic–Paleozoic) using a simplified physically based three-dimensional saturated and unsaturated water-flow model based on Richards’ equation. We were able to calculate the quick discharge during rain and a secondary discharge peak at the watershed simultaneously, using observed topographical information, the topsoil depth distribution, and soil hydraulic characteristics, and by dividing the watershed by 2.5 m horizontally and ten cells vertically. Although the calculated hydrograph did not agree entirely with the observed hydrograph, we conclude that the characteristics of the observed hydrograph were explained with better accuracy using the smaller soil porosity patterns than using the observed patterns. We verified that the simulation method based on Richards’ equation was effective to analyze the rainfall-runoff processes toward the intended watershed. Computational comparisons clarified that lower soil porosity quickens the timing of secondary discharge peaks and increases their volume. Additional examinations, such as the distribution of soil hydraulic characteristics and the actual condition of Hortonian overland flow, are necessary to simulate rainfall-runoff processes precisely at the intended watershed.     

联苯菊酯等3种杀虫剂在茶园茶叶、土壤及降雨径流中的残留

为探究杀虫剂联苯菊酯、溴氰菊酯和虫螨腈的常用剂量和减施剂量对绿茶品种‘丰绿’（Camellia sinensis Yutakmitor）的鲜叶和茶园土壤及降雨径流的影响以及可能产生的膳食摄入风险,选择联苯菊酯、溴氰菊酯和虫螨腈的当地常用剂量和减量30%剂量作为处理组,在浙江绍兴富盛镇御茶村茶园进行田间试验,喷药后1 d、3 d、7 d、10 d分别采集试验小区的鲜叶和土壤,喷药后4 d、8 d采集降雨径流,检测样品中的杀虫剂残留并评估3种杀虫剂的膳食暴露风险。试验结果表明：同种杀虫剂常用剂量处理的茶鲜叶中残留虽然高于减施剂量处理,但二者差异不显著,杀虫剂减量30%对减少鲜叶中的残留并无明显效果。经过常用剂量与减施剂量处理的茶鲜叶中联苯菊酯的半衰期分别为5.89 d和4.61 d,溴氰菊酯的半衰期分别为5.75 d和2.55 d,虫螨腈的半衰期分别为3.72 d和2.70 d。3种杀虫剂在土壤中的残留均低于《土壤环境质量标准（GB 15618-1995）》中有机氯杀虫剂六六六的一级标准值（≤ 0.05 mg·kg^-1）。联苯菊酯和虫螨腈在降雨径流中的残留均低于《生活饮用水卫生标准（GB5749-2006）》中有机氯杀虫剂六六六的限值（0.005 mg·L^-1）,溴氰菊酯在降雨径流中的残留低于《生活饮用水卫生标准（GB5749-2006）》中溴氰菊酯的限值（≤ 0.02 mg·L^-1）。3种杀虫剂在茶叶中的膳食暴露风险评估结果表明,联苯菊酯、溴氰菊酯和虫螨腈的最大暴露量分别为0.5×10^-4~1.7×10^-4 mg·kg^-1（bw）·d^-1、1.0×10^-6~7.3×10^-6 mg·kg^-1（bw）·d^-1、1.0×10^-5~8.3×10^-5 mg·kg^-1（bw）·d^-1,风险商分别为0.005~0.017、0.000 2~0.001和0.000 2~0.003,使用联苯菊酯、溴氰菊酯和虫螨腈防治茶树虫害,对消费者的膳食暴露的风险均可以接受。与常用剂量相比,减施剂量处理对减少茶叶和环境中的杀虫剂残留的效果不明显。     

Efficiency of the geomorphologic instantaneous unit hydrograph method in flood hydrograph simulation

Several methods and models to simulate rainfall-runoff processes have been presented, and each of them has its own advantages and disadvantages. In the present study, different methods were applied to simulate the rainfall–runoff process over the Kasilian Watershed located in northern Iran, including Snyder, SCS, Trianglar, Rosso and Geomorphoclimatic unit hydrographs. The study was intended to compare the accuracy and reliability of a geomorphologic model with Snyder, SCS, Trianglar, Rosso and Geomorphoclimatic Unit hydrographs. In addition, this study attempted to determine the shape and dimensions of outlet runoff hydrographs in a 68.8 km² area in the Kasilian Basin, which is located in the Mazandaran Province of Iran. The first twenty-one equivalent rainfall–runoff events were selected, and a hydrograph of outlet runoff was calculated for each. The peak time and peak flow of outlet runoff in the models were then compared, and the model that most efficiently estimated hydrograph of outlet flow for similar regions was determined. The comparison of calculated and observed hydrographs showed that the geomorphologic model had the most direct agreement for the parameters of peak time and peak flow of direct runoff. Statistical analyses of the models demonstrated that the geomorphological model had the smallest main relative and square error. The study's results confirm the high efficiency of the Geomorphoclimatic Unit Hydrograph and its ability to increase simulation accuracy for runoff and hydrographs.     

Application of a unit hydrograph based on subwatershed division and comparison with Nash's instantaneous unit hydrograph

The Unit Hydrograph (UH) technique is widely used for runoff estimation, especially for determining peak discharges. In this paper, a geomorphologically based UH has been applied. Its most remarkable characteristic is that it includes the watershed structure in its formulation. This is defined from the drainage network, each subwatershed being considered as a linear reservoir. In this method, the fact of considering this reservoir sequence according to the drainage network leads to the formulation of the model only depending on a single parameter. The Geomorphological Unit Hydrograph of Reservoirs (GUHR), proposed in this paper, is compared with Nash's Instantaneous Unit Hydrograph (Nash's IUH), by applying the two methods to the Aixola watershed. This 4.7-km² watershed is located in Gipuzkoa (Northern Spain). It is characteristic of the headwaters watersheds of the area. Most of them are forested and have steep slopes. Annual rainfall is over 1500 mm and many intense rainfall events are observed, among which 18 were selected for this study. Both UH techniques were applied to the rainstorms. The resulting hydrographs were plotted against registered data and the best fits were determined. According to these results, the GUHR model behaved similarly to Nash's IUH. However, the GUHR method seemed able to reproduce a wider range of rainstorms than Nash's IUH. While analyzing the UHs calculated, seasonal behavior was observed in runoff generation, and different average UHs were proposed for two different periods. This variability was also observed in values adopted by the GUHR model parameter, providing some information about the watershed time response. The dynamic character of the only uncertain parameter, and the model formulation, in which the watershed morphology is reflected, together with the model's simplicity, leads us to consider GUHR as being a promising UH model.