Anatomy of extraordinary rainfall and flash flood in a Dutch lowland catchment
Anatomy of extraordinary rainfall and flash flood in a Dutch lowland catchment
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DOI：
10.5194/hess-15-1991-2011
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发表时间：
2011-06
影响因子：
6.3
通讯作者：
C. Brauer;A. Teuling;A. Overeem;Y. Velde;P. Hazenberg;P. Warmerdam;R. Uijlenhoet
中科院分区：
文献类型：
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作者：
C. Brauer;A. Teuling;A. Overeem;Y. Velde;P. Hazenberg;P. Warmerdam;R. Uijlenhoet
抽象的。2010年8月26日，荷兰东部和与德国接壤的地区发生了一系列持续一天多的降雨事件。在740平方公里的面积上，24小时内观测到超过120毫米的降雨量。这一极端事件造成了城市中心、高速公路和农田的局部洪水，并造成了相当大的经济损失。本文报道了由这次特大降雨事件在6.5平方公里的Hupsel Brook流域引发的史无前例的山洪暴发，该流域自20世纪60年代以来一直是瓦赫宁根大学的实验分水岭。这项研究旨在加深我们对这类低地山洪的动态的了解。我们对这次极端事件的水文气象特征进行了详细的分析，重点分析了它的天气气象特征，用雨量计、天气雷达和微波链路观测的它的时空降雨动态，以及测量的土壤水分、地下水和流域的流量响应。在Hupsel Brook集水区，24小时内观测到160毫米的降雨量，相当于估计超过1000年的重现期。7h内流量从5×10−2增加到4.5m3 S−1。集水响应可分为4个阶段：(1)土壤水分蓄水，(2)地下水响应，(3)地表凹陷充填和地表径流，(4)回水反馈。前35毫米的降雨量储存在土壤中，流量没有明显增加。相对干燥的初始条件(与过去的极端流量相比)阻止了更快、更极端的水文反应。
Abstract. On 26 August 2010 the eastern part of The Netherlands and the bordering part of Germany were struck by a series of rainfall events lasting for more than a day. Over an area of 740 km2 more than 120 mm of rainfall were observed in 24 h. This extreme event resulted in local flooding of city centres, highways and agricultural fields, and considerable financial loss. In this paper we report on the unprecedented flash flood triggered by this exceptionally heavy rainfall event in the 6.5 km2 Hupsel Brook catchment, which has been the experimental watershed employed by Wageningen University since the 1960s. This study aims to improve our understanding of the dynamics of such lowland flash floods. We present a detailed hydrometeorological analysis of this extreme event, focusing on its synoptic meteorological characteristics, its space-time rainfall dynamics as observed with rain gauges, weather radar and a microwave link, as well as the measured soil moisture, groundwater and discharge response of the catchment. At the Hupsel Brook catchment 160 mm of rainfall was observed in 24 h, corresponding to an estimated return period of well over 1000 years. As a result, discharge at the catchment outlet increased from 4.4 × 10−3 to nearly 5 m3 s−1. Within 7 h discharge rose from 5 × 10−2 to 4.5 m3 s−1. The catchment response can be divided into four phases: (1) soil moisture reservoir filling, (2) groundwater response, (3) surface depression filling and surface runoff and (4) backwater feedback. The first 35 mm of rainfall were stored in the soil without a significant increase in discharge. Relatively dry initial conditions (in comparison to those for past discharge extremes) prevented an even faster and more extreme hydrological response.