三种JDZ型翻斗式雨量计性能比对实验研究

在我国,JDZ系列翻斗式雨量计已广泛用于降雨量的观测。为了掌握JDZ系列雨量计测量降雨的精度和可靠性,以三种JDZ型翻斗式雨量计(JDZ02、JDZ05和JDZ10)为研究对象,基于一套智能化的雨量计率定系统开展室内性能比对实验。结果表明:(1)以小雨强0.4mm·min^-1作为零误差参考雨强,JDZ02在小于2mm·min^-1时的误差在-4%以内,JDZ05在小于4mm·min^-1时的误差在-4%以内,JDZ10在小于6mm·min^-1时的误差在-4%以内。(2)在雨强-总误差的拟合关系中,二次多项式拟合的效果最好,线性拟合的效果次之,幂函数拟合的效果最差,故建议采用雨强-误差的二次多项式关系订正JDZ系列雨量计监测的降雨数据。(3)左右翻斗水量过程线可以精细刻画翻斗内水量动态变化,判断出翻斗式雨量计的翻斗左右平衡性能,并可计算出翻斗式雨量计动态率定过程中的误差变化。     

Rainfall induced debris flows in pyroclastic deposits, Campania (southern Italy)

A combination of empirical and physically based hydrological models has been used to analyze historical data on rainfall and debris-flow occurrence in western Campania, to examine the correlation between rainfall and debris-flow events.

Rainfall data from major storms recorded in recent decades in western Campania were compiled, including daily series from several rain gauges located inside landslide areas, supplemented by hourly rainfall data from some of the principal storms.

A two-phase approach is proposed. During phase 1, soil moisture levels have been modelled as the hydrological balance between precipitation and evapotranspiration, on a daily scale, using the method of Thornthwaite [Geograph. Rev. 38 (1948) 55].

Phase 2 is related to the accumulation of surplus moisture from intense rainfall, leading to the development of positive pore pressures. These interactions take place on an hourly time scale by the “leaky barrel” (LB) model described by Wilson and Wiezoreck [Env. Eng. Geoscience, 1 (1995) 11]. In combination with hourly rainfall records, the LB model has been used to compare hydrological effects of different storms. The critical level of retained rain water has been fixed by the timing of debris-flow activity, related to recorded storm events.

New rainfall intensity–duration thresholds for debris-flow initiation in western Campania are proposed. These thresholds are related to individual rain gauge and assume a previously satisfied field capacity condition. The new thresholds are somewhat higher than those plotted by previous authors, but are thought to be more accurate and thus need less conservatism.     

Evaluation of rain gauge network in arid regions using geostatistical approach: case study in northern Oman

A geostatistical approach based on ordinary kriging is presented for the evaluation and the augmentation of an existing rain gauge network. The evaluation is based on estimating the percentage of the area that achieves a targeted level of acceptable accuracy. The variances of kriging estimation erros at un-gauged locations were assumed to be normally distributed. Kriging estimation erros with a probability that equals to or exceeds a given threshold value of acceptance probability were assumed to have satisfactory accuracies. The percentage of the area that achieved the targeted probability of acceptance is delineated and used to judge the overall performance of the existing rain gauge network. A study area in northern Oman located in Sohar governorate is selected as the pilot case. The area has 34 rain gauges and it is characterized by a terrain surface that varies from coastal plain to mountains. For a threshold value of 0.85, and 0.90 of acceptance probability, the existing network achieved area of acceptable probability of 88.71 and 77.72 %, respectively. For a success criterion of 80 %, the existing rain gauge network indicated acceptable performance for acceptance probability threshold of 0.85 and inadequate performance is noticed in the case of probability threshold of 0.90, which necessitated further network augmentation. A sequential algorithm for ranking and prioritization of the existing rain gauges is used to classify the existing rain gauges into base and non-base rain gauges. The base rain gauge network for mean annual rainfall comprised about 29 of the existing rain gauges. The identified non-base rain gauges were sequentially relocated to achieve higher levels of percentage of area with acceptable accuracy. The percentage of area with acceptable accuracy increased from 88.71 % for the original rain gauge network to about 94.51 % for the augmented network by adding four rain gages at probability acceptance threshold of 0.85. It also increased from 77.72 % for the existing network to 90.50 % for the augmented rain gauge network at acceptance threshold of 0.9.     

降雨入渗条件下非饱和膨胀土边坡原位监测

为了对降雨诱发的非饱和膨胀土边坡失稳的机理有较深入的了解,在湖北枣阳选取了一个11 m高的典型的非饱和膨胀土挖方边坡进行人工降雨模拟试验和原位综合监测。监测成果表明：降雨入渗造成2 m深度以内土层中孔隙水压力和含水量大幅度增加,致使膨胀土体的抗剪强度由于有效应力的减少及土体吸水膨胀软化而降低;同时,降雨入渗造成土体中水平应力与竖向应力比显著增加,并接近理论的极限状态应力比,以致软化的土体有可能沿着裂隙面发生局部被动破坏,此破裂面在一定条件下（如持续降雨条件下）可能会逐渐扩展,最后发展成为膨胀土中常见的渐进式滑坡。     

Extreme rainfall events: evaluation with different instruments and measurement reliability

With regard to extreme events, it is well documented that an intensity of about 1 mm/min already represents an extreme intensity. Under alpine conditions, a precipitation event with an intensity of 3 mm/min has occurred. Therefore, the rain gauges in this region have to be able to measure in this and even in higher intensity ranges. This study deals with basic automated tipping-bucket rain (TBR) gauge and Bulk precipitation samplers, which are able to hold more than 95 % of the cumulative rainfall, that are verified within the space of the week without losses during the extreme events and with minimal evaporation loss. Bulk samplers collected more rainfall than TBR gauges in 110 of 221 extreme events analysed over the past 10 years. In 17 extreme events, an underestimation greater than 10 % was evaluated. The objective was to single out the counting errors associated with TBR gauge, during extreme events, so as to help the understanding of the measured differences between instruments in the field. We want to determine whether the automated precipitation gauge can provide a reliable and precise measurement of precipitation with particular interest regarding heavy and extreme events.     

Sensitivity analysis of runoff hydrographs due to temporal rainfall patterns in Makkah Al-Mukkramah region,Saudi Arabia

Runoff peak and volume in flood studies are estimated relying on temporal rainfall distribution from various storm patterns. Usually, SCS distributions types (I, II, III, IA) are commonly used. Using these distributions in runoff calculations assume that the in situ temporal rainfall pattern typically behaves as the one described by the SCS-type distribution, which is due to cyclonic frontal storms and actually developed in temperate environment. To what extent such assumption is valid in the arid environment? How much the impacts of rainfall temporal patterns are reflected in runoff volumes and peaks? The aim objectives of the current study are to answer the above two questions and clarify the validity of aforementioned assumption and exemplify such effect. Real rainfall data collected from rain gauges of Makkah Al-Mukkramah region over a period of more than 20 years are utilized. Temporal rainfall patterns and their parameters are deduced. Many hydrological simulations are performed and comparisons, in terms of runoff volume and peak flows, are made to show the effects of the common rainfall storm patterns and the developed rainfall storm patterns in the region based on the current study. Results indicate that major bursts of the design rainfall storm pattern are located in the first time of the storm period in the two quartiles which is mainly due to convective rainfall type in thunderstorms unlike the commonly used by SCS types relying on frontal cyclonic storms. Makkah Al-Mukkramah temporal rainfall pattern does not behave as the “typical pattern” assumed by SCS distributions that are deduced from different environments. The impacts of the temporal pattern reflected as an overestimate in the runoff peak reached to 68 %. The developed hyetographs and tables presented in the current study are recommended to enhance economical and rational design practice in watersheds of Makkah Al-Mukkramah region.     

不同类型降雨过程中GPS可降水量的特征分析

利用成都地基GPS观测网2007年8月21日～2008年11月30日观测数据,结合地面自动气象站网资料反演GPS大气可降水量(P_WV)。选取夏季暴雨,秋季绵雨和冬季雨雪天气过程分析GPSP_WV在不同类型降雨天气过程中的演变特征及日变化规律。结果表明,发生在不同季节的暴雨对应PWV的演变有所不同,盛夏暴雨发生在P_WV由峰值向波谷变化过程中,夏末的暴雨则出现在由波谷向波峰转变阶段,降雨前GPSP_WV的增减速率可很好地预示其后的暴雨强度。在秋季绵雨中P_WV的连续大幅递增或递减可作为降雨开始或结束的预报依据。GPSP_WV在降雨天气分析及预报中具有重要的指示意义。     

The reliability of rainfall data from a volunteer observer network in the Central United States

Summer weekly rainfall data collected by approximately 120 untrained volunteers (mainly farmers) using unofficial gauges in McLean County, Illinois, reveal unambiguous mesoscale patterns. The volunteers collected rainfall data for the County Extension Service as part of an ongoing project spanning many years. All volunteers used the same clear plastic, funnel shaped gauge that could measure up to 140 mm of rain. We found few problems of rainfall distribution, and correlation decay with distance was compatible with decay rates reported elsewhere. Yet local variations in rain day frequencies suggest variable thresholds in the reporting of light rainfalls, and recurrent seasonal patterns of rain day frequency and total rainfall possibly imply data problems or local control. But the large number of sites precludes random observer bias as a factor. Our analysis illustrates that climatologists can safely utilize volunteer observers for research.     

Analysis of rainfall preceding debris flows on the Smědavská hora Mt., Jizerské hory Mts., Czech Republic

In August 2010, extreme rainfall affected the north of the Czech Republic and caused regional floods and landslides. Three torrential debris flows originated in the Jizerské hory Mts., close to Bílý Potok on the north slope of the Smědavská hora Mt. The rainfall situation which triggered the debris flow was analyzed and compared with the rainfall situation in 1958 when a debris flow occurred in the same area. The rainfall data were obtained from rain gauges of the Czech Hydrometeorological Institute. Four rain gauges were chosen close to the Smědavská hora Mt. with data of daily amounts from 1983 to 2013 and 10-min intensity or hourly amounts from the specific period. The data from 1958 were available from three different rain gauges (only daily amounts). The data series were not complete so linear regression was applied to interpolate them. A number of analyses were carried out including daily rainfall, 2-day/3-day moving values, antecedent precipitation index (API) of 5/10/30 days, 10-min intensity, and hourly amounts, and the trigger factor of the debris flow in the study area was also investigated. It was determined that for the triggering of debris flows, both high API values as well as high-intensity short-duration rainfall is needed. It was documented that in cases of solely high API indices or high-intensity short-duration rainfalls, no debris flows were initiated.     

基于多类型雨量计的降雨特性分析

为提高对降雨特性的认识,选择常用的6种测雨设备（翻斗式SL3-1、JDZ05、RG-3,称重式Pluvio2,雨滴谱仪Parsivel2和非计数式JQH-1）,成对布设在南京水利科学研究院滁州水文实验基地的同一个实验场地,同步观测了2019年4月1日至8月31日为期5个月的降雨过程。比测分析得到:在中大雨条件下（日雨量≥ 10 mm）,SL3-1和JDZ05测的降雨总量能够满足4%误差控制要求,RG-3、Pluvio2和Parsivel2测的降雨量比JQH-1测值小4%;在小雨条件下（日雨量 < 10 mm）,翻斗式和称重式雨量计的测量值小于JQH-1测值的4%;SL3-1、RG-3、Pluvio2、Parsivel2测得雨强≤ 0.1 mm/min的频率大于75%,雨强≤ 0.2 mm/min条件下的雨量累积比重大于50%;Pluvio2和Parsivel2监测的降雨开始时间比SL3-1分别早0.5 h和2 h以上,而结束时间分别晚0.5 h和2 h以上。比测结果有助于研究人员选择合适的测量设备获取所关注的降雨特性。     

基于多类型雨量计的降雨特性分析

为提高对降雨特性的认识,选择常用的6种测雨设备（翻斗式SL3-1、JDZ05、RG-3,称重式Pluvio2,雨滴谱仪Parsivel2和非计数式JQH-1）,成对布设在南京水利科学研究院滁州水文实验基地的同一个实验场地,同步观测了2019年4月1日至8月31日为期5个月的降雨过程。比测分析得到：在中大雨条件下（日雨量≥ 10 mm）,SL3-1和JDZ05测的降雨总量能够满足4%误差控制要求,RG-3、Pluvio2和Parsivel2测的降雨量比JQH-1测值小4%;在小雨条件下（日雨量<10 mm）,翻斗式和称重式雨量计的测量值小于JQH-1测值的4%;SL3-1、RG-3、Pluvio2、Parsivel2测得雨强≤ 0.1 mm/min的频率大于75%,雨强≤ 0.2 mm/min条件下的雨量累积比重大于50%;Pluvio2和Parsivel2监测的降雨开始时间比SL3-1分别早0.5 h和2 h以上,而结束时间分别晚0.5 h和2 h以上。比测结果有助于研究人员选择合适的测量设备获取所关注的降雨特性。     

JSP-1型虹吸校正翻斗雨量计研制与特点

翻斗式雨量计因雨强影响会产生很大的误差,虹吸雨量计不能数字化降雨过程,并需要人工测量虹吸水量进行虹吸订正.本研究成果利用翻斗计量降雨过程,用精确的虹吸计量值智能校正翻斗的误差,综合了翻斗计量和虹吸计量的优点,将分辨率为0.1mm的翻斗雨量计的测量误差从±15%减小到±2%.因此,JSP-1型虹吸校正翻斗雨量计具有很高的精度.     

Hydrometeorological thresholds for landslide initiation and forest operation shutdowns on the north coast of British Columbia

Debris flows and debris avalanches are the most widespread and hazardous types of landslides on the British Columbia north coast. Triggered by heavy rain, they pose risks to forestry workers in sparsely developed regions. The scarcity of long-term quality rain gauges and the lack of weather radar information create significant challenge in predicting the timing of landslides, which could be used to warn and, when necessary, evacuate forestry personnel. Traditional methods to relate rainfall antecedents and rainfall intensity to known landslide dates have proven to be unsatisfactory in this study due to extreme spatial variability of rainfall, enhanced by the orographic effect and the scarcity of rain gauges in a very large area. This has led to an integration of meteorological variables in a landslide advisory system that classifies three types of approaching storms by the 850-mbar wind speed and direction, the occurrence of subtropical moisture flow, and the existence of a warm layer characterized by high thickness values of the 500- to 1,000-mbar pressure levels. The storm classification was combined with a 4-week antecedent rainfall and the 24-h rainfall measured near or in the watershed where logging operations are taking place. This system, once implemented, is thought to reduce loss of life, injury, and economic losses associated with forestry works in the study area.     

Spatially distributed rainfall information and its potential for regional landslide early warning systems

Crucial to most landslide early warning system (EWS) is the precise prediction of rainfall in space and time. Researchers are aware of the importance of the spatial variability of rainfall in landslide studies. Commonly, however, it is neglected by implementing simplified approaches (e.g. representative rain gauges for an entire area). With spatially differentiated rainfall information, real-time comparison with rainfall thresholds or the implementation in process-based approaches might form the basis for improved landslide warnings. This study suggests an automated workflow from the hourly, web-based collection of rain gauge data to the generation of spatially differentiated rainfall predictions based on deterministic and geostatistical methods. With kriging usually being a labour-intensive, manual task, a simplified variogram modelling routine was applied for the automated processing of up-to-date point information data. Validation showed quite satisfactory results, yet it also revealed the drawbacks that are associated with univariate geostatistical interpolation techniques which solely rely on rain gauges (e.g. smoothing of data, difficulties in resolving small-scale, highly intermittent rainfall). In the perspective, the potential use of citizen scientific data is highlighted for the improvement of studies on landslide EWS.     

Rainstorm and sediment yield characteristics at Ibadan

Ibadan experiences violent, tropical convectional storms of small areal extent. Hence, it is common observation that whilst very heavy rainfall can occur in one part of the city, another part can be totally dry. The annual average rainfall among stations in Ibadan do not differ significantly.The characteristics of the storms in Ibadan are not well documented. This study was carried out to evaluate and compute some of the characteristics of the Ibadan storm from the normal conventional rainfall autographs.It was found that there are 30 storms in a year accounting for over 70 % of total annual rainfall. It was also found that whilst rain may fall continuously for one or two hours in Ibadan, most of it is concentrated in only 20 minutes of fall which often coincides with the middle portion of the rain period.     

小流域地下裂隙潜流对降雨入渗补给的响应特性

采用翻斗法自动量水技术和时域反射仪,对“岩土二元结构”小流域降雨过程、流域出口地下裂隙潜流以及坡地岩土水分的变化进行了测定与分析。试验结果表明,小流域坡地特有的岩土二元结构体具有较强的储、透水性能,小流域在前期坡地岩土水分平均为14.48%(埋深100cm范围内)的前提下,发生总降雨量170.25mm,降雨历时31h,平均强度5.5mmh的大暴雨,在小流域出口处未产生地表迳流;地下裂隙潜流对降雨具有明显的响应,起涨和回落过程均较为明显,峰值流量达到810Lh,是降雨前的32.4倍。因此,科学合理地利用“岩土二元结构”的水文地质特性对缓解洪峰的形成,降低洪灾具有重要作用,同时对山区的雨水资源化问题也具有重要的实际意义。     

雨量站网布设对水文模型不确定性影响的比较

雨量站网布设会影响径流模拟精度,研究不同雨量站密度和空间分布的径流响应规律对提高径流模拟精度和减小不确定性具有重要意义。应用新安江模型和HBV（Hydrologiska Fyrans Vattenbalans）模型,以湘江流域为研究对象,采用贝叶斯方法比较分析在不同雨量站密度及空间分布下径流模拟的不确定性。结果表明:增加雨量站密度可以降低面雨量的估计误差,使模型在不同的雨量站空间分布下具有较高的模拟精度;通过优化雨量站空间分布,可以减小雨量站网布设导致的模型不确定性,从而提高径流模拟精度;在相同的降雨输入和参数采样方法下,新安江模型和HBV模型对降雨输入导致的不确定性响应规律具有相似性,但是本研究结果显示在湘江流域新安江模型的模拟精度更高,而HBV模型的不确定性更大。     

TRMM3B42降雨数据在渭河流域的应用分析

运用渭河流域24个气象站点日降雨数据对2001~2012年热带测雨卫星(TRMM)3B42数据在不同子流域、不同降雨强度以及不同时间尺度的精度进行了对比验证,并对比分析了基于TRMM和站点数据的渭河流域降雨时空分布特征。结果显示:在不同子流域的日TRMM数据比站点观测数据对低值降雨更为敏感,而在极大值降雨数据观测上两者差距较大,月尺度TRMM站点观测数据确定性系数在0.89到0.96之间;两种数据在流域降雨的时空分布上表现一致性,在年内6月中旬~10月初为湿润多雨期,其余月份降雨较少,空间分布呈东南部大,西北部小的格局。     

Rainfall thresholds for flood triggering. The case of Marathonas in Greece

Basins across Mediterranean coast are often subject to rapid inundation phenomena caused by intense rainfall events. In this flash flooding regime, common practices for risk mitigation involve hydraulic modeling, geomorphic, and hydrologic analysis. However, apart from examining the intrinsic characteristics of a basin, realistic flood hazard assessment requires good understanding of the role of climatic forcing. In this work, peak rainfall intensities, total storm accumulation, average intensity, and antecedent moisture conditions of the 52 most important storms in record, during the period from 1993 to 2008, in northeast Attica, in Greece, are examined to investigate whether there is a correlation between specific rainfall conditions and flood triggering in the area. For this purpose, precipitation data from a network of five rain gauges installed across the study area were collected and analyzed. Storms totals, average intensity, antecedent moisture conditions, and peak intensities variations were calculated and compared with local flooding history. Results showed that among these rainfall measures, only peak storm intensity presents a significant correlation with flood triggering, and a rainfall threshold above which flooding becomes highly probable can be defined.