Volumetric change analysis of the Cauvery delta topography using radar remote sensing

Abstract

Geomorphology refers to the study of the Earth’s physical land surface features. Digital Elevation Model (DEM) is a digital imagery where each pixel represents elevation value above or below mean sea level. The availability of DEM allows analysis of landscape morphology and related processes in terms of geomorphometry. DEM of Difference (DoD) techniques are used to estimate the elevation variations and volumetric changes over time. The volumetric change of terrain in the Cauvery delta (CD) for the past two decades is estimated using DoD algorithm by utilizing freely available moderate spatial resolution SRTM, PALSAR and Sentinel 1A DEMs which are derived by radar remote sensing technique. A detailed assessment of individual DEM’s errors and propagating errors into the DoD are estimated using the field elevation points measured by Real-Time Kinematic (RTK) Global Positioning System (GPS). The default errors in the SRTM, PALSAR and Sentinel 1A DEMs are observed with Root Mean Square Error (RMSE) of 3.33, 3.11 and 3.04 m respectively. The erosion and accretion rates determined are 25 and 30 million m3 / decade correspondingly. The total volume of sediment load due to erosion and accretion is 50 and 60 million m3 respectively during 2000–2020. Further the net area affected due to deposition (69 %) is higher than the total area affected due to erosion (30%). This study presents decadal sediment budget and rate of annual change due to erosion/accretion in the CD.

Keywords

• SRTM
• PALSAR
• Sentinel DEM
• Cauvery delta
• Geomorphic change detection