COMPARING SOME METHODS OF ESTIMATING MEAN AREAL RAINFALL1

ABSTRACT: A comparison of 13 different methods of estimating mean areal rainfall was made on two areas in New Mexico, U.S.A., and one area in Great Britain. Daily, monthly and yearly rainfall data were utilized. All methods, in general, yielded comparable estimates, especially for yearly values. This suggested that a simpler method would be preferable for estimating mean areal rainfall in these areas.     

SPATIAL ANALYSIS FOR MONTHLY RAINFALL IN SOUTH FLORIDA1

ABSTRACT: Several methods have been developed to interpolate point rainfall data and integrate areal rainfall data from any network of stations. From previous studies, it can be concluded that models for spatial analysis of rainfall are dependent on topography, area of analysis, type of rainfall, and density of gauging network. The purpose of this study is to evaluate a set of six appropriate models for point and areal rainfall estimations over a 4000 square mile area in South Florida. In this study, a case of developing spatial continuity model for monthly rainfall from a database that had various lengths of records and missing data is documented. The spatial correlation and variogram models for monthly rainfall were developed. Six methods of spatial interpolation were applied and the results validated with historical observations. The results of the study indicate that the multiquadric, kriging, and optimal interpolation schemes are the best three methods for interpolation of monthly rainfall within the study area. The optimal and kriging methods have the advantage of providing estimates of the error of interpolation. The optimal interpolation method uses the spatial correlation function and the kriging method uses the variogram function. The two spatial functions are related. Either of the two methods provide good estimates of monthly point and areal rainfall in the study area.     

对城市雨水地下回灌的分析

城市扩张带来雨水径量增大,排出时间缩短并由此产生一系列后果,对城区雨水回灌地区的效益进行了讨论,分析城区雨水径流水质污污状况及其影响因素,初期雨水径流污染严重,主要受到地面条件,屋面材料,气温,降雨量及降雨强度等影响,根据对雨水水质的研究结果,分析了雨水回灌地下的条件及必要的雨水处理措施,对雨水回灌技术作了简略的论述。     

深圳市2015~2021年雨源型河流水质时空变化及其对降雨的响应

雨源型城市河流水容量偏小,缺乏动态补充水源,易受污染.基于深圳市2015~2021年全市（不含深汕）9大流域的21个水质指标数据和逐日降雨数据,利用单因子指数评价、综合污染指数、层次聚类分析和Pearson相关分析等方法,研究深圳市河流水质时空分布特征及特征污染物对降雨的响应关系.结果表明：①2015年全区大部分断面水质都是劣Ⅴ类水,2018年10月后河流水质总体得到大幅度改善,与2018年深圳市开展治水专项活动背景一致,到2021年约62%的断面水质达Ⅰ~Ⅲ类水标准;②深圳市（不含深汕）西部人口稠密地区的水质污染较东部更严重,河口和支流下游水质污染较上游更严重;③深圳市坪山河、龙岗河、茅洲河和深圳河的水质受降雨的影响显著;④深圳市河流的主要特征污染指标是DO、COD、BOD₅、NH₄⁺-N、TP、高锰酸盐指数、石油类和阴离子表面活性剂;对于坪山河和龙岗河,降雨使TP和NH₄⁺-N指标浓度升高;对于茅洲河,降雨使TP和COD指标浓度升高;对于深圳河,降雨使COD、TP和NH₄⁺-N指标浓度升高.以上结果能够揭示深圳市雨源型河流水质时空变化情况及其对降雨事件引发的非点源污染的响应关系,为深圳市打造更高品质水环境提供科学参考.     

Differential responses of short-term soil respiration dynamics to the experimental addition of nitrogen and water in the temperate semi-arid steppe of Inner Mongolia, China

We examined the effects of simulated rainfall and increasing N supply of different levels on CO2 pulse emission from typical Inner Mongolian steppe soil using the static opaque chamber technique, respectively in a dry June and a rainy August. The treatments included NH4NO3 additions at rates of 0, 5, 10, and 20 g N/（m2.year） with or without water. Immediately after the experimental simulated rainfall events, the CO2 effluxes in the watering plots without N addition （WCK） increased greatly and reached the maximum value at 2 hr. However, the efflux level reverted to the background level within 48 hr. The cumulative CO2 effluxes in the soil ranged from 5.60 to 6.49 g C/m2 over 48 hr after a single water application, thus showing an increase of approximately 148.64% and 48.36% in the efftuxes during both observation periods. By contrast, the addition of different N levels without water addition did not result in a significant change in soil respiration in the short term. Two-way ANOVA showed that the effects of the interaction between water and N addition were insignificant in short-term soil COz efftuxes in the soil. The cumulative soil CO2 fluxes of different treatments over 48 hr accounted for approximately 5.34% to 6.91% and 2.36% to 2.93% of annual C emission in both experimental periods. These results stress the need for improving the sampling frequency after rainfall in future studies to ensure more accurate evaluation of the grassland C emission contribution.     

SIZING OF SURFACE WATER RUNOFF DETENTION PONDS FOR WATER QUALITY IMPROVEMENT1

ABSTRACT: Historically, storm water management programs and criteria have focused on quantity issues related to flooding and drainage system design. Traditional designs were based on large rainfall‐runoff events such as those having two‐year to 100‐year return periods. While these are key criteria for management and control of peak flows, detention basin designs based on these criteria may not provide optimal quality treatment of storm runoff. As evidenced by studies performed by numerous public and private organizations, the water quality impacts of storm water runoff are primarily a function of more frequent rainfall‐runoff events rather than the less frequent events that cause peak flooding. Prior to this study there had been no detailed investigations to characterize the variability of the more frequent rainfall events on Guam. Also, there was a need to develop some criteria that could be applied by designers, developers, and agency officials in order to reduce the impact of storm water runoff on the receiving bodies. The objectives of this paper were three‐fold: (1) characterize the hourly rainfall events with respect to volume, frequency, duration, and the time between storm events; (2) evaluate the rainfall‐runoff characteristics with respect to capture volume for water quality treatment; and (3) prepare criteria for sizing and designing of storm water quality management facilities. The rainfall characterization studies have provided insight into the characteristics of rainstorms that are likely to produce non‐point source pollution in storm water runoff. By far the most significant fmdings are the development of a series of design curves that can be used in the actual sizing of storm water detention and treatment facilities. If applied correctly, these design curves could lead to a reduction of non‐point source pollution to Guam's streams, estuaries, and coastal environments.     

几种典型红壤模拟降雨条件下的泥沙特征研究

泥沙是土壤侵蚀过程的产物,直接反映了土壤的侵蚀特征。本文利用人工模拟降雨,研究了南方几种典型母质发育红壤侵蚀泥沙的颗粒分布特征、不同粒级中胶结物质的种类和含量。研究结果表明,径流优先选择携带0.002~0.02 mm颗粒,该级别颗粒占泥沙总量的26.68%~60.33%。粘粒含量高的第四纪粘土红壤,泥沙中粗颗粒含量较高,且多为较稳定的团聚体;沙粒和粉粒含量较高的页岩红壤和花岗岩红壤侵蚀泥沙中单粒含量较高,且泥沙分散后粉粒和粘粒的含量高于原土壤。花岗岩红壤侵蚀泥沙中Fe_d,Al_d,Al_o和Si_o含量随泥沙粒径的增大而降低,而泥质页岩红壤和第四纪粘土红壤中,Fe_d,Al_d,Al_o含量随粒径增大而增加,因此其粗粒径泥沙具有较强的稳定性。侵蚀泥沙对有机质有富集作用,泥质页岩红壤和第四纪粘土红壤的粗颗粒对有机质的富集作用强于细颗粒。     

汉江流域1960~2014年降雨极值时空变化特征

深入研究降雨极值的时空变化规律和特点,有助于提高应对极端灾害的能力。通过构建PDS/GP模型,并引入降雨极值变化指标,结合统计检验分析汉江流域15个气象站点1960~2014年春、夏、秋季以及全年月降雨超定量系列的年际变化特征;利用复杂网络理论的聚类系数和节点度,结合各站点在典型年份春、夏和秋季的降雨极值变化指标,分析月降雨极值的空间分布特征。分析结果表明：从时间上看,汉江流域月降雨极值年际变化的季节性差异较大,近55 a没有明显的一致性变化趋势。受季风气候影响,夏季的月降雨极值年际变化与春、秋季相反,而秋季的变异指标年际波动最大。从空间上看,受季风气候、下垫面条件和人类活动等多种因素的综合作用,中下游月降雨极值变化的差异性要高于上游。随着相关阈值的增大,流域站网总体关联度有所降低。相同阈值下的结果表明空间上相邻的站点其关联性差异较大,部分相距较远的站点具有更大的关联性,分析结果可为降雨极值的空间插值提供参考。     

1998年长江大洪水与大气环流和海温异常分析

概述了引起１９９８年长江大洪水的雨情,从天气气候角度分析了１９９８年长江流域降水异常偏多的原因。指出了最直接的原因是副高移动的反常,特别７月１５日以后副高突然南撤南海季风爆发晚,南亚和东亚季风强度偏弱、夏季赤道辐合带偏弱热带地区台风生成少、生成时间晚,