多普勒雷达估测降雨技术在海河流域的应用实践研究

由于雷达的测量范围广、时空分辨率高、能及时取得大面积定量降水资料等优点,将海河流域8部雷达首次进行组网拼图处理,根据实时降雨数据确定雷达的z—I关系,并探讨出适合海河流域的雷达定量降水估测方法,运用2012年“7·21”“7·25”“7·30”3次强降雨进行分析检验,最后得出结论：直接用Z—I关系获得的降水效果最差;基于准同雨团样本概念雷达和雨量计的实时同步结合估测方法次之;变分同化校准法对强降水中心的位置和量级把握得较好,利用该方法可以得到精度更高的降水估测资料。     

基于雷达测雨的降水数据同化研究

提出了基于雷达测雨数据的R-G联合法(即:雷达-雨量计联合法).雨量站的点雨量数据精度高,雷达站测的数据空间分布合理.该方法的思想是:结合两者的优点,得到面上分布合理并且精度高的降水数据.该方法对雨量站分布密度要求不高,受资料等客观条件的限制较小,也无参数选取的限制,更重要的是操作简单方便,结果符合实际降雨情形,在很多方面都优于国内外其他现有的利用雨量计资料订正雷达估测降水的方法.选择站网密度比较理想的湖北东部区域对各方法进行实际应用,通过与传统数据同化方法的对比分析研究,证明R-G联合法明显提高了降水分布形式的合理性和数据同化精度.     

高分辨率面雨量雷达测雨系统在广西左江上游的应用探讨

高分辨率面雨量雷达测雨系统是应用低空雨量雷达进行区域雨量监测,通过雨滴谱仪进行衰减订正后,获取区域内降雨分布和有效的降雨量。通过2台低空雷达组网的左江上游面雨量雷达测雨系统将左江上游平而河和水口河区域概化分为16个区,每小时自动分析、计算、处理16个区域有效面降雨量后,通过开展与相邻的传统雨量监测站数据对比分析,并与广西洪水预报系统衔接开展预警预报的应用,为今后高分辨率面雨量雷达测雨系统在广西的进一步有效应用打下基础。     

雷达联合雨量计估测降水模拟水库入库流量

运用雷达和雨量计联合估测了梅山水库集水区的降水分布。本文根据联合估测结果，应用降水径流模型，对1998、1999年梅山水库入库流量进行了模拟，通过1500h时间序列的模拟试验表明，该模型可以用来模拟梅山水库的入库流量，其结果是合理可用的。与其单独采用雨量计测量面雨量的模拟方法相比，其模拟效果更好。     

康山水库现状防洪能力分析

1洪水分析由于康山水库实测流量资料短缺,水文复核采用《河南省中小流域设计暴雨洪水图集》(1984年出版,以下简称“84图集”)提供数值进行计算。设计暴雨由“84图集”提供雨量进行计算,由于水库流域面积19km~2,小于50km~2,面雨量采用点雨量,水文分区属Ⅱ区,设计面雨量计算按理论频率计算公式Htp= Ht·Kp,偏差系数Cs=3．5Cv,Kp由雨量变差系数查P—Ⅲ曲线Kp值表求得,24小时设计净雨由山丘区次降雨径流关系P Pa～R     

增大适应雨强范围的新型翻斗式雨量计设计

分析了翻斗式雨量计的动作过程误差随雨强增大而增大的关系,设计了一种增大适应雨强范围的分流式翻斗式雨量计,并在理论上对分流式翻斗式雨量计和现有的单翻斗式雨量计的适应雨强范围进行了比较。结果表明:分流式翻斗式雨量计可解决翻斗式雨量计因误差随雨强增大而增大导致的对雨强适应性不强的问题,增大翻斗式雨量计的适应雨强范围,既能保证大雨强时次雨量的计量精度,又能保证小雨强或微雨时的降雨计量次数。     

翻斗式雨量计运作过程误差分析

翻斗式雨量计是一种观测自然界降雨量的设备,它将一定的降雨量转换为开关信息输出,其不同的误差来源对雨量数据采集精度具有不同程度的影响。如何减小雨量数据采集误差,对水资源利用、洪水预报、水文资料整编等工作具有重要意义。通过对翻斗式雨量计进行误差分析,提出通过调节翻斗感量,并根据常年降雨强度统计数据,以及不同雨强下的滴定结果,将翻斗式雨量计应用到更适合的区域,从而减小翻斗式雨量计的降雨量观测误差。     

基于协克里金的雨量雷达融合置信处理方法

针对雨量雷达的“测不准”和雨量计的“测不到”等问题,提出了一种雨量雷达反射率因子的融合置信处理算法,并定量分析了雨量雷达降雨数据的相对置信度。首先对雨量雷达反射率因子数据进行Z-score标准化,再以标准化后的雷达反射率因子数据为辅变量,以雨量计雨量数据为主变量,通过协克里金方法实现数据的融合处理,实现雨量计数据与雨量雷达数据的融合。该算法在数据层实现了雨量计雨量数据与雨量雷达反射率因子数据的融合,并利用相对置信度分析了算法的适用性与稳健性。实测数据与仿真试验验证了融合处理算法的有效性与正确性,为工程应用上雨量雷达探测降雨提供了理论指导。     

流域面雨量的计算方法

降水的空间分布特征是影响径流模拟及一系列其他水文问题的主要控制因素,因此求得区域(流域)平均降水量就显的尤为重要。针对几种常见的区域(流域)面雨量的计算方法进行了总结,并指出雷达测雨跟传统测雨相比可以直接测出面降雨量,因此雷达测雨必然是测雨技术未来的发展方向之一。基于我国目前雨量站的资料密度远不能满足分布流域水文模型的需求,因此需要采用合适的空间插值方法。同时列举了几种插值方法,并对比了其优缺点。     

东江水库入库流量与流域面雨量变化分析

采用2003~2015年东江水库入库流量资料和东江流域内3个气象站点降雨资料,对东江水库入库流量的时间变化特征及其与面雨量的关系进行了分析。结果表明,年平均面雨量与年入库流量呈显著正相关;面雨量与入库流量的转换率年平均为55%,夏季比冬季的降水转换率高,前期的降雨越多转换率越高;大量级、连续降水过程比小量级、分段降水过程的转换率高;洪峰入库时间与流域最大雨强出现时间平均相差4.5 h,不同区域的最大雨强与洪峰流量出现的时间差不一致。利用日面雨量分月建立的日均入库流量预报模型,精度基本满足业务需求,还可以增长水文洪水预报的预见期,在业务上有一定的应用前景。     

雨量站网分布对雨量插值算法及径流响应的影响

为比较雨量站网密度及分布对不同空间插值算法的影响,选取6种雨量站密度的不同分布,采用4种空间插值算法对研究区2006—2014年的日降雨进行插值,并将面均雨量作为新安江模型的输入,分析和比较其降雨径流响应。结果表明:①雨量站网空间分布越均匀,降雨插值误差越小,其径流模拟的精度也越高;②在雨量站网均匀布置的情况下,各空间插值算法的插值结果差异较小;雨量站网布置不均匀时,站点数目越少各空间插值算法插值结果差异越大;③计算点雨量时,考虑空间变量的克里金法能更准确地计算日降雨的结果;计算面雨量时,不同插值算法间差异较小,建议选用计算简便的插值算法,比如泰森多边形、反距离权重法。     

Regional sub-hourly extreme rainfall estimates in Sicily under a scale invariance framework

Design of urban drainage systems or flood risk assessment in small catchments often requires knowledge of very short-duration rainfall events (less than 1 h). Unfortunately, data for these events are often unavailable or too scarce for a reliable statistical inference. However, regularities in the temporal pattern exhibited by storm records, known as scaling properties of rainfall, could help in characterizing extreme storms at partially gauged sites better than the application of traditional statistical techniques. In this work, a scaling approach for estimating the distribution of sub-hourly extreme rainfall in Sicily (Italy) is presented based on data from high-resolution rain gauges with a short functioning period and from low-resolution rain gauges with longer samples. First, simple scaling assumption was tested for annual maxima rainfall (AMR) data from 10 min to 24 h duration, revealing that the simple scaling regime holds from 20 to 60 min for most of the stations. Then, scaling homogeneous regions were classified based on the values of the scaling exponent. In each region, this parameter was regionalized through power-law relationships with the median of 1 h AMR data. After that, regional Depth Duration Frequency (DDF) curves were developed by combining the scale-invariant framework with the generalized extreme value (GEV) probability distribution and used to estimate T-year sub-hourly extreme rainfalls at sites where only rainfall data for longer durations (≥ 1 h) were available. The regional GEV simple scaling model was validated against sub-hourly historical observations at ten rain gauges, generally yielding, in relation to the scaling exponent value, to similar or better sub-hourly estimates than empirical approach.

     

JDZ05-1型雨量数据采集器在降雨观测中的应用

简要介绍JDZ05-1型雨量数据采集器的工作性能,对JDZ05-1型雨量数据采集器与20 cm口径的(普通雨量器和自记雨量计)对比观测的雨量资料进行了回归分析,得出了各雨量站JDZ05-1型雨量数据采集器与普通雨量器、自记雨量计收集的雨量资料之间的相关性,从而揭示相关性的换算变化规律。     

基于雨滴谱仪的降雨雨滴特征分析

利用雨滴谱仪对2019年5—10月和2020年6—7月的雨滴特性进行分析,并与实验场内0.1mm和0.5mm分辨率的雨量计观测数据对比,得到雨滴到达地面时的尾速、直径及其两者之间的关系特征,并探究不同雨强范围雨滴直径的分布情况.结果表明:2019年5—10月出现频率最高的是0.5 mm左右直径雨滴,占比超过20％,0....     

A rationale for using local and regional point rainfall data for design and analysis of urban storm drainage systems

The Danish measuring network for high-resolution rainfall data consists of approximately 70 tipping bucket rain gauges of which 41 have been operated for more than 10 years. The gauges are separated by one to 300 km and cover an area of 43,000 km2. Significant geographical variations of extreme rainfall characteristics have been observed. Part of these variations can be explained by correlation with the mean annual rainfall and the existence of a metropolitan effect in the Greater Copenhagen area. The remaining variation may be attributed to sampling errors and small-scale spatial variations close to the gauges. Engineering methodologies all require rain data of some kind, ranging from design storms based on idf-curves for use in simple calculations to high-resolution time series for use in detailed simulation studies. A comprehensive regional analysis was carried out to account for the geographical variation and to improve estimation for large return periods exceeding the actual length of the measured time series. Ideally, rainfall data used as input to urban drainage calculations should always be based on regional rain information. Regional design storms can be made readily available based on theory developed in this study. However, a satisfactory framework for generating synthetic rain series from regional rain information is not yet available. Thus, there will still be a need for using historical rain series in the near future. To improve the basis for choosing representative historical rain series all the Danish gauges have been classified according to their deviations from the regional distribution.     

Significant climate change of extreme rainfall in Denmark.

During recent years, practitioners of urban drainage have complained that they felt that surcharging occurred more frequently. Therefore, a study was initiated focussing on the variations in extreme rainfall during the last two decades. In Denmark, a total of 41 rain gauges with a high resolution in time and volume have an observation period close to 20 years. The rainfall observed at these gauges was selected for this study. Three variables were analysed for statistically significant trends during the observation period: Maximum average 10 min intensity, maximum average 6h intensity and the total volume of individual rain events. For the 10 min maximum intensity there is a statistically significant trend towards more extreme and more frequently occurring rain storms. The trend is pronounced in the eastern part of the country and below statistically significant levels in the western part of the country. For the 6 h maximum intensity and total volume of events the trends are less pronounced. The findings are confirmed by comparison to physically based climate models and studies based on large regions.     

Roman water law in rural Africa: the unfinished business of colonial dispossession

This study reviews combined rainfall observation using both radar and rain gauges. Sampling error theory is introduced and applied to an evaluation of the rain gauge network of the upstream region of the Imjin River Basin in North Korea. Under the assumption that the Ganghwa Radar is properly calibrated, an additional 13 rain gauges (including the eight that are currently in operation) is deemed sufficient to secure the quality of rainfall observation with 37 rain gauges without radar.     

分布式水文模型结合雷达测雨用于三峡区间的洪水预报

长江三峡区间因暴雨形成的洪水峰高量大, 对三峡水库防洪安全和运行调度的影响不容忽视。依据三峡地区的地形地貌特征,采用基于 GIS的分布式水文模型来模拟区间洪水过程,以尽量减小洪水预报中的不确定性。研究表明 ,降雨信息缺失是洪水预报不确定性的主要来源,尤其是在雨量站稀疏的山区,雨量站观测 的降雨信息难以充分表征降雨空间变化。为此,进一步尝试利用雷达测雨数据作为分布式水 文模型的输入,通过对2个小流域的示例研究,结果表明雷达测雨能捕获降雨的空间分布, 它与分布式水文模型相结合,是提高洪水预报精度的有效途径之一。     

Spatial Distribution and Seasonal Variability of Rainfall in a Mountainous Basin in the Himalayan Region

The average distribution of precipitation provides essential input for understanding the hydrological process. The role of complex topography in mountainous basins makes the spatial distribution of precipitation different than the plain areas. Besides the rugged topography, the Himalayan basins also face the problem of limited physical accessibility and data availability. In this study, seasonal and annual distribution of rainfall with elevation and distance from the lower most station (Akhnoor) has been studied for the Chenab basin (western Himalayas). The study basin covers all the three ranges i.e. outer, middle and greater Himalayas. The rainfall stations are grouped into windward and leeward categories. The trends of spatial distribution of rainfall are discussed in detail. Attempts are also made to investigate the impact of reduced network on the mean annual rainfall of the Chenab basin. A reduction in rain gauges from 42 to 19 has resulted in an increase in the estimate of mean annual rainfall by 14% with respect to the estimate obtained using 42 stations network.     

Influence of systematic errors from tipping bucket rain gauges on recorded rainfall data

Tipping bucket rain gauges (TBR) are widely used in urban hydrology. The present study investigated the uncertainties in recorded rainfall intensity induced by the following properties of the TBR: depth resolution i.e. the bucket volume, calibration parameters, wetting and evaporation losses and the method of data recording (time between tips or tips per minute). The errors were analysed by means of a TBR simulator i.e. a simulation program that models the behaviour of a TBR. Rainfall data disaggregated to 6 seconds from measured 1-min data and randomly varied were taken as input to the simulator. Different TBR data series were produced by changing the properties of the simulated rain gauge. These data series together with the original rainfall events were used as input to a rainfall-runoff model. Computed overflow volume and peak discharge from a combined sewer overflow (CSO) weir were compared. Errors due to depth resolution (i.e. the bucket size) proved to be small. Therefore TBRs with a depth resolution up to 0.254 mm can be used in urban hydrology without inducing significant errors. Wetting and evaporation losses caused small errors. The method of data recording had also little influence. For larger bucket volumes variable time step recording induced smaller errors than tips per minute recording.