Abstract:
Soil erosion by water is the most prevalent environmental problem in the central highlands of Sri Lanka.
On the above context, the soil conservation is critically required in these areas. Uma Oya watershed in
central highland is one of the most important sensitive areas with regard to soil erosion. Digital terrain
modeling in Geo-informatics is a useful tool for identifying and prioritizing areas for soil and water
conservation which are critical to restoring and protecting for crop production. This paper is focused on
the use of Geo-informatics techniques to identifying and prioritizing vulnerable places for soil
conservation in Uma Oya watershed and visualizing, to better planning and identifying erodible hotspots
for soil and water conservation. An integrated soil erosion hazard map of Uma Oya watershed was
generated by using Geographic Information Systems (GIS) and existing land use pattern and landslide
incident layers in the GIS environment Data analysis was performed using 3D analysis tool in the spatial
analysis. The soil erosion hazard map clearly shows that nearly 63% of total area of the watershed is
highly vulnerable for soil erosion. Eleven micro-watersheds were delineated based on drainage systems.
5 Out of 11 micro-water sheds fell under severer soil erosion categories of the soil loss severity classes, of
which two of them are in the extremely high erosion categories. These identified erodible hotspots can be
assessed for further evaluation to install on farm and off farm conservation structures in a sustainable
manner.
