TITLE:
Assessment of Land Erosion and Sediment Accumulation Caused by Runoff after a Flash-Flooding Storm Using Topographic Profiles and Spectral Indices
AUTHORS:
A. Bannari, G. Kadhem, A. El-Battay, N. A. Hameid, M. Rouai
KEYWORDS:
Soil Erosion, Sediments Transport and Accumulation, Flood-Storm, Runoff, Climate Change, Remote Sensing, GIS, Topographic Profiles, Landsat-8, ASTER-DEM
JOURNAL NAME:
Advances in Remote Sensing,
Vol.5 No.4,
December
15,
2016
ABSTRACT: This research deals with the characterization of areas associated with flash floods and
erosion caused by severe rainfall storm and sediment transport and accumulation
using topographic attributes and profiles, spectral indices (SI), and principal component
analysis (PCA). To achieve our objectives, topographic attributes and profiles
were retrieved from ASTER-V2 DEM. PCA and nine SI were derived from two Landsat-OLI images acquired before and after the flood-storm. The images data were atmospherically
corrected, sensor radiometric drift calibrated, and geometric and topographic
distortions rectified. For validation purposes, the acquired photos during
the flood-storm, lithological and geological maps were used. The analysis of approximately
100 colour composite combinations in the RGB system permitted the selection
of two combinations due to their potential for characterizing soil erosion classes
and sediment accumulation. The first considers the “Intensity, NDWI and NMDI”,
while the second associates form index (FI), brightness index (BI) and NDWI. These
two combinations provide very good separating power between different levels of soil
erosion and degradation. Moreover, the derived erosion risk and sediment accumulation
map based on the selected spectral indices segmentation and topographic
attributes and profiles illustrated the tendency of water accumulation in the landscape,
and highlighted areas prone to both fast moving and pooling water. In addition,
it demonstrated that the rainfall, the topographic morphology and the lithology
are the major contributing factors for flash flooding, catastrophic inundation, and
erosion risk in the study area. The runoff-water power delivers vulnerable topsoil
and contributes strongly to the erosion process, and then transports soil material and
sediment to the plain areas through waterpower and gravity. The originality of this research resides in its simplicity and rapidity to provide a solid basis strategy for regional
policies to address the real causes of problems and risks in developing countries.
Certainly, it can help in the improvement of the management of water regulation
structures to develop a methodology to maximize the water storage capacity and
to reduce the risks caused by floods in the Moroccan Atlas Mountain (Guelmim region).