High-Accuracy Elevation Data at Large Scales from Airborne Single-Pass SAR Interferometry

Abstract

Digital elevation models (DEMs) are essential data sets for disaster risk management and humanitarian relief services as well as many environmental process models. At present, on the one hand, globally available DEMs only meet the basic requirements and for many services and modeling studies are not of high enough spatial resolution and lack accuracy in the vertical. On the other hand, LiDAR-DEMs are of very high spatial resolution and great vertical accuracy but acquisition operations can be very costly for spatial scales larger than a couple of hundred km 2 and also have severe limitations in wetland areas and under cloudy and rainy conditions. The ideal situation would thus be to have a DEM technology that allows larger spatial coverage than LiDAR but without compromising resolution and vertical accuracy and still performing under some adverse weather conditions and at a reasonable cost. In this paper, we present a novel single pass In-SAR technology for airborne vehicles that is cost-effective and can generate DEMs with a vertical error of around 0.3 m for an average spatial resolution of 3 m. To demonstrate this capability, we compare a sample single-pass In-SAR Ka-band DEM of the California Central Valley from the NASA/JPL airborne GLISTIN-A to a high-resolution LiDAR DEM. We also perform a simple sensitivity analysis to floodplain inundation. Based on the findings of our analysis, we argue that this type of technology can and should be used to replace large regions of globally available lower resolution DEMs, particularly in coastal, delta and floodplain areas where a high number of assets, habitats and lives are at risk from natural disasters. We conclude with a discussion on requirements, advantages and caveats in terms of instrument and data processing.

Rapid Mapping of Small-Scale River-Floodplain Environments Using UAV SfM Supports Classical Theory

“…However, here, we only tested for basic characterization of in-channel hydraulics and floodplain inundation mapping and therefore recommend more complete investigations of the suitability of drone-acquired DTMs for flood modeling and mapping. In fact, in line with the conclusion drawn by Schumann et al [24] for a novel airborne InSAR DEM technology, what is also needed here is a proper hydraulic modeling benchmark study, preferably using a floodplain and a flood event for which LiDAR data have been used.…”

“…For flood-fill modeling we followed the procedure adopted by Schumann et al [24]. This method is based on calculating a floodplain elevation profile from the digital terrain model (DTM) data (often referred to as bare earth DEM), which describes floodplain water depth as a function of flooded area [25].…”

The Need for a High-Accuracy, Open-Access Global DEM

“…The operation costs would therefore be substantially cheaper than most satellite missions. Schumann et al (2016) further stated that such a DEM could be achieved from a consortium of industry, governments and humanitarian agencies and would undoubtedly be the environmental equivalent of the Human Genome Project (HGP; NIH, 2010) but at a fraction of the cost (see Sampson et al, 2016).…”

A Method to Assess Localized Impact of Better Floodplain Topography on Flood Risk Prediction

“…An important point of this study is that although the targeted observation analysis (as proposed by Andreadis and Schumann [8]) can be used to assess the impact new measurements of important variables have on the prediction of flood hazard and although we showed how inclusion of socioeconomic data can augment that analysis, there is the substantial caveat that the verification model in our case was only based on higher resolution (90 m) SRTM topography and not on high accuracy elevation data, for example, from LiDAR or new InSAR technology [1]. Nevertheless, we believe this analysis to be worthwhile and suggest this type of study to be repeated for other large river areas in particular in countries deprived of high resolution floodplain DEMs so that the case for a better global DEM [2] can be supported.…”

“…Remote sensing is commonly used to measure topography and instruments typically include altimeters (radar or LiDAR), synthetic aperture radar (SAR) interferometry, and photogrammetry from optical imagery; even unmanned aerial vehicles (UAV) are being used more recently to acquire DEMs. Vertical errors can range from several meters, typical for satellite DEM technology, for example, from the Shuttle Radar Topography Mission (SRTM, http://www2.jpl.nasa.gov/srtm/) or ASTER, down to the decimeter in the case of airborne LiDAR, airborne photogrammetry, and also novel airborne single-pass SAR interferometry as recently demonstrated by Schumann et al [1].…”