Abstract
Abstract. The high-resolution accurate topography data should be used for extreme and nuisance flood inundation modeling and mapping in cities, but not available for many cities, including most developed countries. It is necessary to study and identify an alternate open-source topographic model that satisfies high-resolution topography datasets’ conditions. We analyzed the open-source DEMs visually, elevation histogram statistics, streams and watershed identification, contour statistics, Topographic Wetness Index, and vertical accuracy of other medium-resolution DEMs compared with high-resolution LiDAR data over New York City to determine alternative open-source Digital Elevation Model in the context of urban flood modeling. In high urban sprawl areas, in the context of flood mapping, our findings have shown that the medium resolution DEMs predicted similar to high-resolution DEMs with the same linear errors around RMSE 25–35ft and LE90 30–40ft. Overall, the ALOS AW3D performed better than other open-source DEMs. Even though SRTM predicted well, it inducted smoothness in DEM where more buildings were located. It noted that ALOS PALSAR DEM is not suitable for any urban studies. ASTER DEM has also shown good agreement with LiDAR and observed elevations, but it induced by noise while processing. Finally, it can be suggested that the ALOS AW3D can be used as an alternative source for urban flood modeling which represented footprints of buildings even though it performed average in vertical accuracy.
Highlights
To map the flood inundations, for extreme and nuisance floods in urban areas, the topography has become an essential data
At 30m spatial resolution, the building footprints are barely seen in NED and ALOS PALSAR, indicating smooth DEMs (DTM)
ALOS AW3D, ASTER, and SRTM show which is due to the response of land cover classes to radar or optical sensors is comparable (Grohmann, 2018)
Summary
To map the flood inundations, for extreme and nuisance floods in urban areas, the topography has become an essential data. ASTER GDEM (Tachikawa et al, 2011), SRTM (Farr et al, 2007), ALOS AW3D (Tadono et al, 2016) are freely available global datasets, TanDEM-X (Krieger et al, 2007) is both commercial (10m,30m) and freely available (30m) global data. Accepted that high-resolution topographic models are necessary to map accurate flood inundations and forecasting (Sanders, 2007). To achieve this many highend technologies (Optical Photogrammetry, radar-based interferometry and airborne LiDAR etc) developed and adopted towards the direction of producing high-resolution DEM datasets such as IKNOS, SPOT, CARTOSAT (5m-actual acquisition resolution by ISRO), TanDEM-X, ALOS AW3D (5m-actual acquisition resolution by JAXA), LiDAR (sub-centimetre level) cloud points etc. Many researchers are carried out to assess the accuracy of DEMs towards fluvial floods, river modeling etc.,
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