GIS Based landform classification using digital elevation model: a case study from two river basins of Southern Western Ghats, Kerala, India

Abstract

The main purpose of this study is to classify/characterize the landforms within a river basin using complex spatial information and GIS application to recognize and extort geomorphologic properties of Digital Elevation model with 30 m resolution. The landform classification is based on the Topographic position index (TPI) of the area under study—the Ithikkara and Kallada river basins, Southern Western Ghats, Kerala, India. The TPI generated was used for classifying the landscape to slope position index and landform classes. The slope position classes identified are Ridges/Hilltop/Canyon edge, Upper slope, Mid slope, Flat, Lower slope and Valley. The Landform classes includes (1) Canyons, deeply incised streams, (2) Midslope drainages, shallow valleys, (3) Upland drainages, headwaters, (4) U-shaped valleys, (5) Plains, (6) Open slopes, (7) Upper slopes, mesas, (8) Local ridges/hills in valleys, (9) Midslope ridges, small hills in plains and (10) Mountain tops, high ridges. 50.23% of the study area belongs to the slope position class—Ridges/Hilltop/Canyon edge. 30% of the study area is occupied by the landform class Canyons and deeply incised streams followed by Mountain tops and high ridges which covers 28.16%. The U shaped valleys represent 12.32% of the study area. The validation of landform classes is done by overlaying the stream network of the basin is into the landform classes, which is perfectly overlapping with the U shaped valleys of the landform classes. The classification of landform from the study can be used in applications related to precision agriculture, land use alteration studies where the most dominant factor is landform.