Geomorphometric delineation of floodplains and terraces from objectively defined topographic thresholds
Geomorphometric delineation of floodplains and terraces from objectively defined topographic thresholds
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DOI：
10.5194/esurf-5-369-2017
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发表时间：
2017-07-10
影响因子：
3.4
通讯作者：
Limaye, Ajay B.
中科院分区：
文献类型：
--
作者：
Clubb, Fiona J.;Mudd, Simon M.;Limaye, Ajay B.
洪泛区和阶地特征可提供关于当前和过去河流过程的信息，包括河道对不同流量和沉积物通量的反应、沉积物储存以及集水区的气候或构造历史。以前的方法识别洪泛平原和梯田的数字高程模型（DEM）往往是半自动化的，需要输入独立的数据集或手动编辑的用户。在这项研究中，我们提出了一种新的方法，识别洪泛平原和阶地功能的基础上两个阈值：当地的梯度，海拔相比，最近的渠道。这些阈值是使用分位数-分位数图从DEM中统计计算的，不需要为每个景观手动设置。我们测试我们的方法对现场绘制的洪泛区起始点，公布的洪水灾害地图，并从七个现场从美国和一个现场从英国的数字化梯田表面。对于每个站点，我们使用来自光探测和测距（激光雷达）的高分辨率DEM，以及较粗分辨率的国家数据集来测试我们的方法对网格分辨率的敏感性。我们发现，我们的方法是成功的，在提取洪泛区和阶地的功能相比，实地测绘的数据范围内的景观和网格分辨率测试。该方法在感兴趣的特征和周围景观之间的坡度和海拔对比度最大的区域中最准确，例如封闭的山谷设置。我们的方法提供了一个新的工具，快速，客观地识别洪泛区和梯田功能的景观尺度上，应用包括洪水风险图，重建景观演变，和量化的沉积物存储和路由。
Floodplain and terrace features can provide information about current and past fluvial processes, including channel response to varying discharge and sediment flux, sediment storage, and the climatic or tectonic history of a catchment. Previous methods of identifying floodplain and terraces from digital elevation models (DEMs) tend to be semi-automated, requiring the input of independent datasets or manual editing by the user. In this study we present a new method of identifying floodplain and terrace features based on two thresholds: local gradient, and elevation compared to the nearest channel. These thresholds are calculated statistically from the DEM using quantile-quantile plots and do not need to be set manually for each landscape in question. We test our method against field-mapped floodplain initiation points, published flood hazard maps, and digitised terrace surfaces from seven field sites from the US and one field site from the UK. For each site, we use high-resolution DEMs derived from light detection and ranging (lidar) where available, as well as coarser resolution national datasets to test the sensitivity of our method to grid resolution. We find that our method is successful in extracting floodplain and terrace features compared to the field-mapped data from the range of landscapes and grid resolutions tested. The method is most accurate in areas where there is a contrast in slope and elevation between the feature of interest and the surrounding landscape, such as confined valley settings. Our method provides a new tool for rapidly and objectively identifying floodplain and terrace features on a landscape scale, with applications including flood risk mapping, reconstruction of landscape evolution, and quantification of sediment storage and routing.