Characteristics of rain events at an inland locality in northeastern Borneo,Malaysia

Understanding the intensity and duration of tropical rain events is critical to modelling the rate and timing of wet‐canopy evaporation, the suppression of transpiration, the generation of infiltration‐excess overland flow and hence to erosion, and to river responsiveness. Despite this central role, few studies have addressed the characteristics of equatorial rainstorms. This study analyses rainfall data for a 5 km² region largely comprising of the 4 km² Sapat Kalisun Experimental Catchment in the interior of northeastern Borneo at sampling frequencies from 1 min^?1 to 1 day^?1. The work clearly shows that most rainfall within this inland, forested area is received during regular short‐duration events (<15 min) that have a relatively low intensity (i.e. less than two 0·2 mm rain‐gauge tips in almost all 5 min periods). The rainfall appears localized, with significant losses in intergauge correlations being observable in minutes in the case of the typical mid‐afternoon, convective events. This suggests that a dense rain‐gauge network, sampled at a high temporal frequency, is required for accurate distributed rainfall‐runoff modelling of such small catchments. Observed rain‐event intensity is much less than the measured infiltration capacities, and thus supports the tenet of the dominance of quick subsurface responses in controlling river behaviour in this small equatorial catchment. Copyright © 2006 John Wiley & Sons, Ltd.     

Temporal variations of reference evapotranspiration and controlling factors: Implications for climatic drought in karst areas

Variations in reference evapotranspiration (ET₀) and drought characteristics play a key role in the effect of climate change on water cycle and associated ecohydrological patterns. The accurate estimation of ET₀ is still a challenge due to the lack of meteorological data and the heterogeneity of hydrological system. Although there is an increasing trend in extreme drought events with global climate change, the relationship between ET₀ and aridity index in karst areas has been poorly studied. In this study, we used the Penman–Monteith method based on a long time series of meteorological data from 1951 to 2015 to calculate ET₀ in a typical karst area, Guilin, Southwest China. The temporal variations in climate variables, ET₀ and aridity index (AI) were analyzed with the Mann–Kendall trend test and linear regression to determine the climatic characteristics, associated controlling factors of ET₀ variations, and further to estimate the relationship between ET₀ and AI. We found that the mean, maximum and minimum temperatures had increased significantly during the 65-year study period, while sunshine duration, wind speed and relative humidity exhibited significant decreasing trends. The annual ET₀ showed a significant decreasing trend at the rate of ?8.02 mm/10a. However, significant increase in air temperature should have contributed to the enhancement of ET₀, indicating an “evaporation paradox”. In comparison, AI showed a slightly declining trend of ?0.0005/a during 1951–2015. The change in sunshine duration was the major factor causing the decrease in ET₀, followed by wind speed. AI had a higher correlation with precipitation amount, indicating that the variations of AI was more dependent on precipitation, but not substantially dependent on the ET₀. Although AI was not directly related to ET₀, ET₀ had a major contribution to seasonal AI changes. The seasonal variations of ET₀ played a critical role in dryness/wetness changes to regulate water and energy supply, which can lead to seasonal droughts or water shortages in karst areas. Overall, these findings provide an important reference for the management of agricultural production and water resources, and have an important implication for drought in karst regions of China.     

半干旱沙地-草甸区水面蒸发模拟及其影响因子辨识

在分析半干旱沙地—草甸区的水面蒸发过程及其影响因子的基础上,采用多元逐步回归分析方法,对水面蒸发的众多影响因子进行逐步筛选,找出显著影响因子,建立水面蒸发与其显著影响因子间的多元非线性回归模型,并模拟计算了彭曼蒸发公式、道尔顿水汽运输理论蒸发公式中的风函数,比较分析了彭曼模型、变异道尔顿模型、多元非线性回归模型计算的水面蒸发量。结果表明:彭曼模型、变异道尔顿模型和最终建立的多元非线性逐步回归模型所得结果十分接近,与实测水面蒸发量的趋势也很一致;除变异道尔顿模型稳定性稍差外,其余两者都具有较好的稳定性;多元非线性逐步回归方法可以找到水面蒸发的显著影响因子,剔除掉不显著影响因子,避免因子相关造成的影响,使所建回归模型具有良好的拟合效果,其决定系数达到了0.773,预测结果令人满意。     

樟树市气象干旱特征及重现期分析

利用樟树市1960—2018年逐月降水和气温资料,计算标准化降水蒸散指数（SPEI）,并结合游程理论和Copula函数分析了该地区干旱特征。结果表明：樟树市干旱形势总体上趋于缓和,干旱历时和干旱烈度均呈减弱趋势,且呈现出良好的相关性;Frank-Copula函数可作为描述该地区干旱历时和干旱烈度的二维联合分布最优函数;在相同干旱历时和烈度下,“且”的重现期大于“或”的重现期,樟树市历史干旱事件的干旱历时多小于5个月,“且”的重现期小于10 a。     

劳动争议案件时效制度的法律思考

针对我国劳动争议案件处理的时效制度和仲裁前置程序的规定直接影响劳动争议的解决,提出取消仲裁前置程序,由当事人自愿选择仲裁或诉讼;或者,可以保留劳动争议仲裁的前置程序,但应将仲裁时效与诉讼时效严格区分。     

A bivariate gamma distribution for use in multivariate flood frequency analysis

A gamma distribution is one of the most frequently selected distribution types for hydrological frequency analysis. The bivariate gamma distribution with gamma marginals may be useful for analysing multivariate hydrological events. This study investigates the applicability of a bivariate gamma model with five parameters for describing the joint probability behavior of multivariate flood events. The parameters are proposed to be estimated from the marginal distributions by the method of moments. The joint distribution, the conditional distribution, and the associated return periods are derived from marginals. The usefulness of the model is demonstrated by representing the joint probabilistic behaviour between correlated flood peak and flood volume and between correlated flood volume and flood duration in the Madawask River basin in the province of Quebec, Canada. Copyright © 2001 John Wiley & Sons, Ltd.     

Jordan日照记录阈值分析

本文是通过10个月的日射、日照资料对比观测、统计的乔唐、康氏和光电式日照计记录阈值的平均值和标准偏差,分析了乔唐日照计进光孔径、涂药方式对感光迹线的影响,测定了感光药的吸收光谱,并根据日出日没时直接日射辐照度的平均变化率,估算了由阈值的不确定度引起的日照时数的误差,从而为我国几十年的乔唐日照资料的评价提供依据。     

Complex Site Effects in Thessaloniki (Greece): I. Soil Structure and Comparison of Observations with 1D Analysis

This paper presents a 2D model of the geological structure of Thessaloniki city and results of empirical and theoretical approaches for the evaluation of site response due to complex site effects. The construction of the 2D model is based on the available geophysical and geotechnical data in terms of the most important parameters needed to model site response. The well-known subsoil structure, despite the existence of some local uncertainties, gave the possibility to correlate the geometry and the dynamic properties of the 2D model with the results of site response determined from the analysis of one event in frequency and time domains and 1D numerical modelling. The study of site response shows the effect of the lateral variations on ground motion and suggests that the contribution of locally generated surface waves to the resonant peak may be important. In this case history, the limitations of the 1D approximation to simulate ground motion under complex soil conditions in both frequency and time domains are also shown. This paper lays the ground for a companion article dealing with 2D site effects.     

Comparison of the return period for landslide-triggering rainfall events in Japan based on standardization of the rainfall period

The intensity of rainfall events with potential to cause landslides has varying temporal characteristics. In this study, the time at which the 72-h accumulated rainfall reached its maximum was used to standardize the period of rainfall measurement. The proposed standardization of the rainfall period was used in conjunction with the return level of rainfall intensity, obtained from intensity–duration–frequency curves, to investigate rainfall intensity anomalies associated with 10 hazardous rainfall events that triggered numerous landslides at the regional scale in Japan. These landslides included shallow landslides in volcanic and non-volcanic areas, as well as deep-seated landslides. The rainfall events that triggered the shallow landslides were divided into two types: downpours that repeatedly reached close to the 100-year return level within approximately 3–4 h, and accumulated rainfall that reached close to 200–400 mm over longer time intervals but within 72 h. Lithological differences seemed unrelated to the differences between the two types of shallow-landslide-triggering rainfall; however, precipitation >1000 mm was necessary to trigger deep-seated landslides. Although the characteristics of the hyetographs differed markedly among the landslide-triggering rainfall events, all the landslides could have been triggered when the mean rainfall intensity reached the 100-year rainfall level during the standardized period. Thus, the landslide trigger can be evaluated indirectly based on the increase in the return level of the mean rainfall intensity, which could provide a means for estimating the time of landslide occurrence.     

甘肃时段暴雨主要统计参数的水平分布规律研究

甘肃是一个干旱同时又是暴雨多发的省份。通过介绍与暴雨关系密切的甘肃自然地理概况,选用甘肃境内及其周边700个雨量站的观测资料,在统计计算10min、60min、6h、24h、3d这5个时段在每个时段的多年平均时段最大暴雨量和变差系数的基础上,研究了5个时段的两个主要统计参数在甘肃省境内的水平分布规律。对甘肃及其周边干旱地区的公路铁路建设、暴雨洪水集蓄利用、水土保持和防洪减灾等具有重要意义。