Innovate UK: Improved probabilistic mapping and modelling of groundwater flooding in urban areas

有必要更好地了解地下水在城市洪水中的作用——在最近一次大洪水（2013/14年冬季）之后，四分之一的索赔主要与“地下水”机制引起的洪水有关。此外，现有的地下水制图解决方案没有量化在给定的重现期预计洪水的预期影响程度，而是进行高/中/低分类。我们将创建一个新颖的软件工具，允许在一个广泛的区域内对地表和地下水流动进行动态模拟。目前，这种代表整个水系统的工具并不以动态形式存在（即两层随着时间的推移相互反应和变化）。地下水驱油主要有两种类型：由地表水驱油驱动的渗透性浅层沉积（PSD）和地下水位切断地下水位的清水驱油。前者，即PSD，发生在浅层沉积物传播洪水波并导致地下水在传统洪水风险方法确定的范围之外泛滥的时候。后者既可以以地表积水的形式出现，也可以以流水的形式出现。这两种不同类型的地下水洪水需要两种不同的方法：河流、溪流和排水沟的地表水水位将驱动地下水的水头。因此，需要开发一种将地表水水头与地下水水头连接起来的方法。Clearwater -基于Upton和Jackson （2011; http://nora.nerc.ac.uk/13501/）开发的方法，通过地下水点模型（AquiMod）生成动态地下水表面。一旦产生了适当的地下水水头，这些可以与DTM相结合，产生修订的地下水洪水图。将开发白垩岩上透水性浅层沉积（PSD）和清水驱的集总参数地下水模型。两个建议的地区是牛津的psd和肯利/克罗伊登的克利尔沃特洪水。前者（PSD）将需要与环境地表水模型建立联系，以驱动地下水响应，后者可以用于洪水范围模型。一旦制订了综合系统，就将进行下列工作：对容易发生洪水的地区进行评估——这将采取使用OpenData（英国地质勘探局地质图、环境局地下水位数据、操作系统数据）的形式来开发地下水洪水风险图。3.区域评估PSD及清水区水浸-将模型方法扩展至第(1)项所述易受水浸影响的地区。气候变化对洪水风险概率的影响和变化。

There is a need to better understand the role of groundwater in urban flooding - a quarter of claims following the most recent major flooding (winter 2013/14) were associated with flooding predominantly from a 'groundwater' mechanism. Additionally, existing groundwater mapping solutions, do not quantify the expected degree of impact of flooding expected for a given return period - rather a high/med/low classification. We will create a novel software tool that allows for the dynamic simulation of surface and groundwater flow, over a wide area. Currently such a tool which represents the entire water-system does not exist in a dynamic form (i.e. where the two layers react and change with one-another over time).There are two main types of groundwater flooding: Permeable Superficial Deposits (PSD) driven by surface water flooding and Clearwater flooding where the groundwater table cuts the groundwater surface. The former, PSD, occurs when superficial deposits transmit the flood wave and results in groundwater flooding outside that identified by traditional flood risk approaches. The latter can take the form of surface ponding as well as flowing features. These two distinct types of groundwater flooding require two different approaches:1. PSD - surface water levels in rivers, streams and drains will drive the groundwater head. Therefore a method needs to be developed that links the surface water heads to groundwater heads.2. Clearwater - Based on the method developed by Upton and Jackson (2011; http://nora.nerc.ac.uk/13501/) to produce a dynamic groundwater surface produced from groundwater point models (AquiMod). Once the appropriate groundwater heads are produced these can be combined with a DTM to produce a revised groundwater flood map. lumped parameter groundwater models for Permeable Superficial Deposits (PSD) and Clearwater flooding on the Chalk will be developed. The two suggested areas are Oxford for PSDs and Kenley/Croydon for Clearwater flooding. The former (PSD) will need to develop a linkage with Ambiental surface water models to drive the groundwater response and the latter can feed into flood extent models. Once the integrated system has been developed then the following will be undertaken: 1. Assessment of areas prone to flooding - this will take the form of using OpenData (BGS geological maps, Environment Agency groundwater level data, OS data) to develop risk maps for groundwater flooding.2. Regional assessment of PSD and Clearwater flooding - by extending the modelling approach applying this to the flood prone areas identified in (1). 3. Climate change impacts and changes to flood risk probability.