Improved understanding of spatio-temporal controls on regional scale groundwater flooding using hydrograph analysis and impulse response functions
Improved understanding of spatio-temporal controls on regional scale groundwater flooding using hydrograph analysis and impulse response functions
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DOI：
10.1002/hyp.11380
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发表时间：
2017-12-15
影响因子：
3.2
通讯作者：
Bloomfield, John Paul
中科院分区：
文献类型：
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作者：
Ascott, Matthew J.;Marchant, Ben P.;Bloomfield, John Paul
尽管地下水洪水事件持续时间长，社会和经济影响明显，但对地下水洪水时空范围的控制知之甚少。我们开发了一种新的方法，使用地下水位过程线和脉冲响应函数（IRF）的统计分析，并将其应用于2013/2014年在英国低地白垩地下水洪水。我们提出了一个标准化的地下水泛滥指数，我们计算了26个钻孔的白垩每月地下水位。我们使用k-means聚类分析对这些标准化系列进行分组，并将聚类中心与1至60个月的时间间隔内累积的标准化降水指数进行交叉相关。该分析揭示了2个空间相干组的标准化过程线，响应于不同的时间尺度的降水。我们估计了IRF模型的地下水位响应有效降水的3个钻孔，每组。IRF模型证实了标准化降水指数分析，表明各组之间的响应函数不同。我们将相同的有效降水量输入到每个IRF模型中，并观察到每组水文过程之间的差异。据认为，这是由于白垩的水文地质性质和覆盖相对低渗透性的表层沉积物（最近未固结的沉积物覆盖基岩，如粘土和冰碛），这是广泛的一个组。地下水洪水响应的总体控制的结论是一个复杂的组合的先决条件，降雨量和流域水文地质特性。在预测和管理未来的地下水洪水事件时，应考虑这些控制措施。所提出的方法是通用的和简约的，可以很容易地应用在有足够的地下水位和降雨量数据。
Controls on the spatio-temporal extent of groundwater flooding are poorly understood, despite the long duration of groundwater flood events and distinct social and economic impacts. We developed a novel approach using statistical analysis of groundwater level hydrographs and impulse response functions (IRFs) and applied it to the 2013/2014 Chalk groundwater flooding in the English Lowlands. We proposed a standardized index of groundwater flooding which we calculated for monthly groundwater levels for 26 boreholes in the Chalk. We grouped these standardized series using k-means cluster analysis and cross-correlated the cluster centroids with the Standardized Precipitation Index accumulated over time intervals between 1 and 60months. This analysis reveals 2 spatially coherent groups of standardized hydrographs that responded to precipitation over different timescales. We estimated IRF models of the groundwater level response to effective precipitation for 3 boreholes in each group. The IRF models corroborate the Standardized Precipitation Index analysis showing different response functions between the groups. We applied identical effective precipitation inputs to each of the IRF models and observed differences between the hydrographs from each group. It is suggested this is due to the hydrogeological properties of the Chalk and of overlying relatively low permeability superficial deposits (recent unconsolidated sediments overlying the bedrock, such as clays and tills), which are extensive over 1 of the groups. The overarching controls on groundwater flood response are concluded to be a complex combination of antecedent conditions, rainfall, and catchment hydrogeological properties. These controls should be taken into consideration when anticipating and managing future groundwater flood events. The approach presented is generic and parsimonious and can be easily applied where sufficient groundwater level and rainfall data are available.