Earth and Planetary Sciences ETDs

Publication Date



Soil moisture variability across four river systems in Ganges Basin, from the Tista and Kosi Rivers in the east to the Gandak and Ghaghra-Rapti Rivers in the west, was assessed using Landsat TM Band 6 imagery dating from 1999-2003. The Band 6 thermal channel of Landsat is sensitive to soil temperature variability resulting from differences in moisture content and as such is a proxy for soil moisture variability in this environment. In order to take advantage of this relationship we analyzed the imagery focusing on the range of thermal values across the fans. This range calculation separates seasonally dry and perennially wet soils on the basis of variability in their moisture content throughout the year. Soils that have a high range (high variability) show significant drying after the monsoon, while those that exhibit a low range indicate either constant wet or dry conditions and/or vegetation that does not vary seasonally. Ground based assessments of soil characteristics on the Tista and Kosi fans support this image analysis. Our work, supported by literature, indicates that the Tista DFS (Distributive Fluvial System) and the Ghaghra-Rapti interfluve, where river is currently incised and detached from its floodplain, show an increase in soil moisture content downstream. However, the Kosi and Gandak DFSs, which have higher rate of subsidence and are not incised under current climatic conditions, show no trend in soil moisture distribution. This study indicates that degree of incision and water table depth are important controls for soil moisture distribution across the DFSs in this area.

Degree Name

Earth and Planetary Sciences

Level of Degree


Department Name

Department of Earth and Planetary Sciences

First Advisor

Weissmann, Gary

First Committee Member (Chair)

Weissmann, Gary

Second Committee Member

Schuderi, Louis

Third Committee Member

Meyer, Grant




thermal band, soil moisture, ganges basin, distributive fluvial system

Document Type