Traditional Shuttle Radar Topography Mission (SRTM) topographic datasets hold limited value in the geomorphic analysis of low-relief terrains. To address this shortcoming, this paper presents a series of techniques designed to enhance digital elevation models (DEMs) of environments dominated by low-amplitude landforms, such as a fluvial megafan system. These techniques were validated through the study of a wide depositional tract composed of several megafans located within the Brazilian Pantanal. The Taquari megafan is the most remarkable of these features, covering an area of approximately 49,000km 2. To enhance the SRTM-DEM, the megafan global topography was calculated and found to be accurately represented by a second order polynomial. Simple subtraction of the global topography from altitude produced a new DEM product, which greatly enhanced low amplitude landforms within the Taquari megafan. A field campaign and optical satellite images were used to ground-truth features on the enhanced DEM, which consisted of both depositional (constructional) and erosional features. The results demonstrate that depositional lobes are the dominant landforms on the megafan. A model linking baselevel change, avulsion, clastic sedimentation, and erosion is proposed to explain the microtopographic features on the Taquari megafan surface. The study confirms the potential promise of enhanced DEMs for geomorphological research in alluvial settings.
|Number of pages||11|
|State||Published - Aug 1 2012|
Bibliographical noteFunding Information:
We acknowledge the financial support of the São Paulo Research Foundation—FAPESP (grants 2006/02381-8 and 2007/55987-3 ) and the National Council for Scientific and Technological Development—CNPq (grant 305108/2009-3 ). We are grateful to Dr. Márcio de Morisson Valeriano for suggestions and discussions regarding the manuscript structure and figure layout. Dr. Martin Thorp and an anonymous reviewer are thanked for their suggestions and comments that helped to improve an early draft of this paper.
- Digital elevation model (DEM)
ASJC Scopus subject areas
- Earth-Surface Processes