Is rainfall intensity significant in the rainfall–runoff process within tropical rainforests of northeast Queensland? The Hewlett regression analyses revisited     

Andrew J. Howard  Mike Bonell  Don Gilmour  David Cassells 《水文研究》2010,24(18):2520-2537

Following the statistical analyses of long‐term rainfall‐runoff records from research basins in humid temperate latitudes, Hewlett and co‐workers extended the global challenge to disprove their findings that rainfall intensity was non‐significant. This paper responds to Hewlett's challenge as no preceding analyses have involved forested basins in a tropical cyclone‐prone area. Based on a 7 year rainfall‐runoff record, quickflow (QF), peak flow (QP) and quickflow response ratios (QRR) were regressed as dependent variables against rainfall parameters (intensity, P_i, amount, P), storm duration, D and antecedent flow, I. These data sets were categorised into total streamflow (Q) classes and stratified into three seasons, (monsoon, post‐monsoon and dry) for forested and cleared catchments. Where rainfall variable collinearity met acceptable levels, the addition of P_i to regression models including P, D, I contributed up to 9% and 66% of the respective variations in quickflow and peak flow. For the highest Q storm classes (monsoon), P_i alone accounted for up to 67% and 91% of the variation in Q_F and Q_P respectively and was the dominant influence on Q_P for all seasons. The very high rainfall intensities experienced in the monsoon season is a causal factor why these results differ from those of other research drainage basins. Surprisingly, P_i continued to have a significant influence on Q_F for dry season classes when less‐intense rainfall occurs. Further the results were similar for both catchments across all seasons. P was the dominant independent variable affecting Q_F above a threshold Q of 50 mm (monsoon), as rainfall contributes directly to saturation overland flow and return flow under saturated conditions. Further although QRR increased with increasing Q for each season, the regression results for that parameter were poor possibly due to the non‐linearity of the rainfall‐runoff relationship. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Assessing the impact of climate variability and human activities on streamflow from the Wuding River basin in China     

Li-Juan Li  Lu Zhang  Hao Wang  Juan Wang  Jun-Wei Yang  De-Juan Jiang  Jiu-Yi Li  Da-Yong Qin 《水文研究》2007,21(25):3485-3491

Located in the Loess Plateau of China, the Wuding River basin (30 261 km²) contributes significantly to the total sediment yield in the Yellow River. To reduce sediment yield from the catchment, large-scale soil conservation measures have been implemented in the last four decades. These included building terraces and sediment-trapping dams and changing land cover by planting trees and improving pastures. It is important to assess the impact of these measures on the hydrology of the catchment and to provide a scientific basis for future soil conservation planning. The non-parametric Mann–Kendall–Sneyers rank test was employed to detect trends and changes in annual streamflow for the period of 1961 to 1997. Two methods were used to assess the impact of climate variability on mean annual streamflow. The first is based on a framework describing the sensitivity of annual streamflow to precipitation and potential evaporation, and the second relies on relationships between annual streamflow and precipitation. The two methods produced consistent results. A significant downward trend was found for annual streamflow, and an abrupt change occurred in 1972. The reduction in annual streamflow between 1972 and 1997 was 42% compared with the baseline period (1961–1971). Flood-season streamflow showed an even greater reduction of 49%. The streamflow regime of the catchment showed a relative reduction of 31% for most percentile flows, except for low flows, which showed a 57% reduction. The soil conservation measures reduced streamflow variability, leading to more uniform streamflow. It was estimated that the soil conservation measures account for 87% of the total reduction in mean annual streamflow in the period of 1972 to 1997, and the reduction due to changes in precipitation and potential evaporation was 13%. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

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

Kawi Bidin  Nick A. Chappell 《水文研究》2006,20(18):3835-3850

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.  相似文献   

Efficient stochastic analysis of unsaturated slopes subjected to various rainfall intensities and patterns     

《地学前缘(英文版)》2023,14(1):101490

Rainfall infiltration poses a disastrous threat to the slope stability in many regions around the world. This paper proposes an extreme gradient boosting (XGBoost)-based stochastic analysis framework to estimate the rainfall-induced slope failure probability. An unsaturated slope under rainfall infiltration in spatially varying soils is selected in this study to investigate the influences of the spatial variability of soil properties (including effective cohesion c′, effective friction angle φ′ and saturated hydraulic conductivity k_s), as well as rainfall intensity and rainfall pattern on the slope failure probability. Results show that the proposed framework in this study is capable of computing the failure probability with accuracy and high efficiency. The spatial variability of k_s cannot be overlooked in the reliability analysis. Otherwise, the rainfall-induced slope failure probability will be underestimated. It is found that the rainfall intensity and rainfall pattern have significant effect on the probability of failure. Moreover, the failure probabilities under various rainfall intensities and patterns can be easily obtained with the aid of the proposed framework, which can provide timely guidance for the landslide emergency management departments.  相似文献   

Temporal variations of reference evapotranspiration and controlling factors: Implications for climatic drought in karst areas          下载免费PDF全文

Guo Xiao-jiao  Wang Wen-zhong  Li Cheng-xi  Wang Wei  Shi Jian-sheng  Miao Ying  Hao Xing-bo  Yuan Dao-xian 《地下水科学与工程》2022,10(3):267-284

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.  相似文献   

重庆多历时极值降水的概率型优选及应用     

王颖  刘晓冉  程炳岩  孙佳 《气象科学》2020,40(4):560-568

基于重庆34个国家气象站1981—2016年5 min,24 h至3 d的过程最大雨量共18个年极值降水序列,利用线性矩法计算6种常用概率分布函数的模型参数,通过备选最优模型筛选法客观选取各站各历时极值降水的最优概率模型,并将优选结果应用于重庆不同历时百年重现期降水的计算。结果表明:模型优选方法得到的重庆各站不同历时极值降水的最优线型略有差异,广义极值分布占比最大,三参数Weibull分布次之,三参数对数正态分布第三,皮尔逊Ⅲ型和Gumbel分布相当,指数分布最差。最优线型计算的重庆不同历时百年重现期降水的空间分布大值区由短历时的点状分布向长历时的片状分布转变,渝东北的大值中心受地形影响不断向北移动。基于线性矩法的概率模型参数估计及客观的线型优选过程具有较强的可操作性和适应性,可应用于其他工程气象参数的推算中。  相似文献   

樟树市气象干旱特征及重现期分析          下载免费PDF全文

刘喆玥  韩会明  赖亮  杨立苑  徐全倩 《气象与减灾研究》2020,43(2):117-122

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。  相似文献   

准噶尔盆地西北缘一次大到暴雨天气过程分析     

孙东霞 《沙漠与绿洲气象(新疆气象)》2013,7(3)

摘要：通过分析2010年6月２8～２9日发生在准噶尔盆地西北缘的一次大到暴雨天气,揭示了形成这次强降水天气的环流背景特点、物理量和雷达回波特征。结果显示：冷暖气团在克拉玛依地区附近相遇产生的中尺度锋生现象触发了本次暴雨天气过程。表现最明显的特征是：高空槽移动缓慢,中层切变线不断南压、低层中尺度系统维持,冷暖气团在区域强烈交汇。暴雨区雷达速度场有明显的风场幅合。对流降水云团强度、移向变化的预测,是此类天气临近预报的关键和难点。  相似文献   

劳动争议案件时效制度的法律思考     

赵万忠 《广东海洋大学学报》2005,25(2):24-26

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。  相似文献   

A bivariate gamma distribution for use in multivariate flood frequency analysis     

Sheng Yue 《水文研究》2001,15(6):1033-1045

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.  相似文献