Bias corrections of CartoDEM using ICESat-GLAS data in hilly regions

There are a number of digital elevation models (DEMs) existing worldwide for studying the topography, estimating elevation differences over time and runoff modeling, soil erosion estimation, and so forth, including vertical changes on glaciers. There are various techniques and instruments/sensors used for surface elevation data collection and for monitoring surface changes. Satellite data-based DEMs have been available at global level during the past two decades. Errors and biases may persist in these elevation data-sets. This may be due to limitations of the techniques, sensor instabilities, bad surveying conditions on the ground, and post-processing artifacts. Elevations derived from Geoscience Laser Altimeter System/Ice, Cloud and land Elevation Satellite (GLAS/ICESat) data are one of the most reliable globally available data. The objective of this study is to present a simple and effective method to compute planimetric offsets in the DEM of hilly terrain using GLAS data and perform necessary corrections for improving the elevation accuracy. A slope-based method has been employed for the co-registration of overlapping elevation surfaces for Chandra and Bhaga basins in the Himalaya. Accuracy assessment has been done by computing standard deviation of offsets, which is an indicator of the variability of error distribution. As a result of bias corrections, the standard deviations have decreased from 10.8 m to 6.0 m and 9.0 m to 7.05 m for Chandra and Bhaga basins, respectively.