Controls on event runoff coefficients in the eastern Italian Alps   总被引：3，自引：0，他引：3  

Daniele Norbiato  Marco Borga  Ralf Merz  Günther Blschl  Alberto Carton 《Journal of Hydrology》2009,375(3-4):312-325

Analyses of event runoff coefficients provide essential insight on catchment response, particularly if a range of catchments and a range of events are compared by a single indicator. In this study we examine the effect of climate, geology, land use, flood types and initial soil moisture conditions on the distribution functions of the event runoff coefficients for a set of 14 mountainous catchments located in the eastern Italian Alps, ranging in size from 7.3 to 608.4 km². Runoff coefficients were computed from hourly precipitation, runoff data and estimates of snowmelt. A total of 535 events were analysed over the period 1989–2004. We classified each basin using a “permeability index” which was inferred from a geologic map and ranged from “low” to “high permeability”. A continuous soil moisture accounting model was applied to each catchment to classify ‘wet’ and ‘dry’ initial soil moisture conditions. The results indicate that the spatial distribution of runoff coefficients is highly correlated with mean annual precipitation, with the mean runoff coefficient increasing with mean annual precipitation. Geology, through the ‘permeability index’, is another important control on runoff coefficients for catchments with mean annual precipitation less than 1200 mm. Land use, as indexed by the SCS curve number, influences runoff coefficient distribution to a lesser degree. An analysis of the runoff coefficients by flood type indicates that runoff coefficients increase with event snowmelt. Results show that there exists an intermediate region of subsurface water storage capacity, as indexed by a flow–duration curve-based index, which maximises the impact of initial wetness conditions on the runoff coefficient. This means that the difference between runoff coefficients characterised by wet and dry initial conditions is negligible both for basins with very large storage capacity and for basins with small storage capacity. For basins with intermediate storage capacities, the impact of the initial wetness conditions may be relatively large.  相似文献   

我国南方夏季低频雨型的季节内水汽输送特征   总被引：3，自引：2，他引：1       下载免费PDF全文

左金清  任宏利  李维京  张培群  杨明珠 《地球物理学报》2009,52(9):2210-2221

利用1962～2006年NCEP/NCAR再分析资料,采用对历史个例进行合成分析的方法,研究了异常降水中心分别位于长江以南区域的江南型和长江-淮河流域的江淮型低频雨型的季节内水汽输送特征.研究表明,江南型的总水汽输送主要来源于孟加拉湾,并经中南半岛和南海输入江南区域;江淮型的总水汽输送主要直接来源于南海,但水汽源地主要为印度季风区.对于水汽输送异常,江南型和江淮型具有明显不同的特征.江南型的水汽输送异常主要来源于热带西太平洋-南海,中纬度西风带和中高纬度南下的水汽输送异常的贡献次之;而江淮型的水汽输送异常主要来源于热带和副热带西太平洋,中纬度西风带水汽输送异常的贡献次之.另外,水汽输送异常对江南型的区域总水汽收支的贡献约为50%,而对江淮型的区域总水汽收支的贡献高达70%左右.因此,虽然总水汽输送主要取决于气候平均水汽输送,但是,水汽输送异常与气候平均水汽输送对江南型和江淮型的水汽供应具有相同甚至更为重要的贡献.特别是对于江淮型,区域总水汽收支主要取决于水汽输送异常的贡献,而水汽输送异常的变化较平均水汽输送更为复杂,这有可能是江淮流域汛期降水预报较为困难的原因之一.  相似文献   

汾河水库以上流域径流变化与洪水频率分析     

高建峰  任健美  胡彩虹 《中国沙漠》2009,29(3):577-582

根据1970—2004年的实测水文资料,采用水文学及统计方法分析了汾河水库控制流域的径流量变化及其原因,同时还计算了不同重现期的控制站的洪峰设计值。结果表明,入库控制站静乐和上静游站丰、平和枯水水平年不同步,在20世纪70和80年代发生丰水和平水年份比较多,在90年代后枯水年份比较多,多干旱年份。水库控制流域洪水主要集中在7月、8月,同时极端洪涝和干旱事件出现的频次增多。以静乐站为代表分析降水对径流变化的结果表明,高强度降水在量级和次数上存在波动变化的态势,年径流的时序变化主要是受年降水量的变化影响。  相似文献   

近50年气候变化对滦河上游径流的影响     

王亮  朱仲元  刘轩晓  何桥 《高原气象》2012,31(4):1158-1165

为了解近50年滦河上游气温和降水气候的变化特征、趋势及其对该流域径流量的影响,利用1956-2009年滦河上游的实测气温、降水量和径流深资料,分析了该流域气温、降水和径流深的年均和季度变化的时间序列,并建立了该流域气候变化对径流影响的复相关回归模型。结果表明,年径流深随着年降水量的减少而减少,随着年平均气温的升高而减少;春、夏和秋季的径流深随着同期降水量和气温的变化趋势与年际变化趋势基本一致,但冬季径流深则相反,而且其变化幅度非常小。  相似文献   

Comparative policy analysis: Neoliberalising New Zealand     

J. Richard Peet 《New Zealand geographer》2012,68(3):151-167

Comparative policy analysis involves systematically examining the long‐term formation of public policies across a number of societies. It focuses particularly on the sequence of policy regimes: liberalism – Keynesianism/social democracy – neoliberalism. Since 1980, neoliberalism has been widely adopted as the guiding ideological structure for economic policy making. But neoliberalism encounters resistances that vary with national contexts. New Zealand is a particularly interesting case because of its reputation as a social democratic, welfare state that went neoliberal with a vengeance (Rogernomics).  相似文献   

蚌埠闸及上游闸坝对淮河自然水文情势的影响   总被引：3，自引：0，他引：3  

胡巍巍 《地理科学》2012,(8):1013-1019

淮河流域建设了许多闸坝,为揭示如此密集的闸坝对河流自然水文情势的影响,选取比较典型的淮河干流上的蚌埠闸作为控制节点,用成熟的IHA法和RVA法,研究蚌埠闸及其上游闸坝对水文情势的影响程度,同时通过蚌埠水文站水文情势变化的估算来分析闸坝对淮河河流生态水文条件的影响。结果显示,这些闸坝对河流水文情势的影响强烈,特别是在枯水季节。由此得出的淮河蚌埠段生态水文目标可为蚌埠闸开展生态系统管理、生态修复以及进行生态调控提供理论支持。  相似文献   

1961—2009年辽河流域水文气象要素变化特征   总被引：1，自引：0，他引：1  

梁红  孙凤华  隋东 《辽宁气象》2012,(1):59-64

依据1961—2009年辽河流域5个气象观测站点逐日降水和气温观测资料,运用非参数检验方法（Mann-Kendall法）,对辽河流域降水和气温的变化趋势进行了分析。利用2006—2010年夏季共162d降水日的铁岭站日降水量与铁岭水文站径流量资料,探讨了日降水量与径流量之间的相关关系。结果表明：辽河流域年降水量减少趋势明显,降水量偏少年份明显增加,其主要原因为占全年降水量65%的夏季降水以7.4 mm/10 a的气候趋势倾向率递减,呈现出明显的减少趋势;辽河流域的年平均气温是在波动中逐渐上升的,且升温趋势明显,春季呈明显的升温趋势,夏季略有下降,秋季变化不大,冬季是气温上升最明显的季节;日降水量与径流量存在正相关关系,且日降水量与降水第二日的径流量相关显著。  相似文献   

Streamflow regimes of the Yanhe River under climate and land use change,Loess Plateau,China   总被引：1，自引：0，他引：1       下载免费PDF全文

Peng Gao  Guantao Jiang  Yongping Wei  Xingmin Mu  Fei Wang  Guangju Zhao  Wenyi Sun 《水文研究》2015,29(10):2402-2413

Soil and water conservation measures including terracing, afforestation, construction of sediment‐trapping dams, and the ‘Grain for Green Program’ have been extensively implemented in the Yanhe River watershed, of the Loess Plateau, China, over the last six decades, and have resulted in large‐scale land use and land cover changes. This study examined the trends and shifts in streamflow regime over the period of 1953–2010 and relates them to changes in land use and soil and water conservation and to the climatic factors of precipitation and air temperature. The non‐parametric Mann–Kendall test and the Pettitt test were used to identify trends and shifts in streamflow and base flow. A method based on precipitation and potential evaporation was used to evaluate the impacts of climate variability and changes in non‐climate factors changes on annual streamflow. A significant decrease (p = 0.01) in annual streamflow was observed related to a significant change point in 1996, mostly because of significant decreases in streamflow (p = 0.01) in the July to September periods in subsequent years. The annual base flow showed no significant trend from 1953 to 2010 and no change point year, mostly because there were no significant seasonal trends, except for significant decreases (p = 0.05) in the July to September periods. There was no significant trend for precipitation over the studied time period, and no change point was detected. The air temperature showed a significant increasing trend (p < 0.01), and 1986 (p < 0.01) was the change point year. The climate variability, as measured by precipitation and temperature, and non‐climate factors including land use changes and soil and water conservation were estimated to have contributed almost equally to the reduction in annual streamflow. Soil and water conservation practices, including biological measures (e.g. revegetation, planting trees and grass) and engineering measures (such as fish‐scale pits, horizontal trenches, and sediment‐trapping dams) play an important role in reduction of the conversion of rainfall to run‐off. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Quantifying Water Pollution Sources in a Small Tile‐drained Agricultural Watershed          下载免费PDF全文

Petr Fučík  Tomáš Hejduk  Jana Peterková 《洁净——土壤、空气、水》2015,43(5):698-709

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地下河系统水动态监测网络优化对比分析:以桂林海洋-寨底地下河系统为例     

邹胜章  杨苗清  陈宏峰  朱丹尼  周长松  李录娟  谢浩 《地学前缘》2019,26(1):326-335

基于我国南方地区岩溶发育极不均匀、水位水质动态变化快的特点,通过对信息熵法和防污性能法所得结果的对比,分析在缺少系列监测资料条件下,利用岩溶水系统防污性能评价结果快速布设地下河系统水动态监测网的可行性及其布设原则。根据防污性能评价结果,结合水循环特征,桂林海洋-寨底地下河系统水动态监测网需由17个监测站组成;采用信息熵法对现有35个监测站进行优化后,认为只需要12个监测站就可组成最优监测网,但这12个监测站点与采用防污性能评价法得到的点位完全重合,且均位于防污性能差的地区。对比分析认为,以地下水系统防污性能评价结果布设地下水动态监测网是可行性的,因为岩溶发育区既是防污性能差的地区,也是地下水动态变化快的地区,能充分反映地下河系统水质水量变化。采用防污性能评价法布设地下水动态监测网时,需要充分认识和了解地下河系统水文地质条件和地下河管道结构特征,且需要遵循以下原则:(1)在岩溶发育相对较弱的系统中部(基本上不存在防污性能差的地区)不设置监测站点;(2)在距离地下河出口较近的岩溶发育区内(即防污性能差的地区)监测站点可由地下河出口替代;(3)对于多支管道系统,岩溶发育相对较弱且距离较短的小型支管道上可以不布设监测站,由支管道与主管道交汇处的监测站代替。  相似文献