To model future extreme water levels due to Sea Level Rise (SLR), subsidence and the worsening of storm surges, we require coastal elevation data having a high accuracy (within 1 m) and for all the coastal areas of the world. To do so, local airborne lidar data is sometimes used, but because this is expensive, it is not available everywhere.
From an article by Deltares.
In areas where this data is missing, for instance in South-East Asia, we fall back on global elevation models to assess – among others – coastal flood risk. However, these models measure the upper part of canopy and buildings also, and thus do not represent the bare earth and height everywhere. The differences between the model and terrain can be tens of meters for vegetated areas.
The newly developed DeltaDTM is the first global coastal elevation model that has an accuracy within 1 m, marking an important step in the usability of global elevation models to assess sea level rise for instance. Maarten Pronk, a PhD candidate at the Delft University of Technology and an elevation modelling expert at Deltares, was responsible for creating the model.
Maarten: “Ever since the global satellite lidar data became available, we have made plans to improve global terrain models. Former colleagues Ronald Vernimmen and Aljosja Hooijer (now both at Data for Sustainability) and I started out with a 5 km model (GLL_DTM). We have now improved upon this work, by including even more lidar data and fusing with existing elevation models, to reach a 30 m resolution. It required a thousand times more compute power, which we solved by extensively parallelizing our workflow in the Julia programming language.”
Global lidar data
The high accuracy of DeltaDTM is achieved by combining the most recent radar-based global CopernicusDEM elevation model with satellite lidar data, freely distributed by the NASA ICESat-2 and GEDI missions. “These missions are ongoing, so we can expect further updates and improvements to DeltaDTM in the near future” says Maarten Pronk.
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