Comparative assessment of different digital elevation models for morphometric analysis of Godavari river sub basin

Abstract

The present study was undertaken to carry out morphometric analysis of the Godavari river sub basin using three types of digital elevation models (DEMs) viz., CARTOSAT, shuttle radar topographic mission (SRTM, 30 m resolution and advanced space-borne thermal emission and reflection radiometer (ASTER 30 m resolution). The delineated area of sub-basin was obtained as 3654.79, 3621 and 3529.3 km2 using CARTOSAT, SRTM and ASTER DEM, respectively. The delineated area of the sub basin using CARTOSAT, and SRTM DEM were nearly the same, whereas ASTER DEM showed small deviation. Total number of streams of all orders delineated from CARTOSAT, SRTM and ASTER DEM were 23593, 21682 and 22969, respectively, indicating a small deviation. The total stream length of the sub basin using CARTOSAT, SRTM and ASTER DEM were 9755.49 km, 6645.11km, and 9752.63 km, respectively. The CARTOSAT, SRTM and ASTER DEMs showed similar results for the elongation ratio and length of overland flow. The CARTOSAT and SRTM DEM exhibited the same relief as 501 m, whereas ASTER DEM resulted in 512 m relief. The logarithmic plotting position of a number of streams against stream orders indicated a decrease in the number of streams in geometric progression with an increase in stream order in all DEMs. The form factor (R ) ranges from 0.05, 0.03 and 0.02 in CARTOSAT, SRTM f and ASTER DEM, respectively of the sub-basin indicating an elongated shape. The circularity ratio (R ) of the whole basin was computed as 0.32, 0.28 and 0.26 in c CARTOSAT, SRTM and ASTER DEM, respectively indicating the dendritic stage of the basin. The value of the constant of channel maintenance (C) was computed as 0.37, 0.37 and 0.36 using CARTOSAT, SRTM and ASTER DEM, respectively, indicating high structural disturbance, low permeability, steep to very steep slopes and high surface runoff in the sub-basin. The drainage density (D ) of the whole basin was d computed to be 2.67, 2.69 and 2.76 km km-2 using CARTOSAT, SRTM and ASTER DEM, respectively. The closeness of results through all the DEMs indicates the acceptability of all the DEMs for morphometric analysis.