STUDY AREA AND DATA

The Uttara Kannada district lies 74°9' to 75°10' E longitude and 13°55' to 15°31' N latitude, extending over an area of 10,291 km² in the mid-western part of Karnataka state (Fig. 2). It accounts for 5.37 % of the total area of the state with a population above 1.2 million [23]. This region has gentle undulating hills, rising steeply from a narrow coastal strip bordering the Arabian sea to a plateau at an altitude of 500 m with occasional hills rising above 600–860m.

Fig. 2. Uttara Kannada district, Karnataka, India

This district, with 11 taluks, can be broadly categorised into three distinct regions –– coastal lands (Karwar, Ankola, Kumta, Honnavar and Bhatkal taluks), mostly forested Sahyadrian interior (Supa, Yellapur, Sirsi and Siddapur taluks) and the eastern margin where the table land begins (Haliyal, Yellapur and Mundgod taluks). Climatic conditions range from arid to humid due to physiographic conditions ranging from plains, mountains to coast.

Survey of India (SOI) toposheets of 1:50000 and 1:250000 scales were used to generate base layers – district and taluk boundaries, water bodies, drainage network, etc. Field data were collected with a handheld GPS. RS data used in the study were Landsat MSS (1973, spatial resolution – 79m), Landsat TM (1989, spatial resolution – 30m), Landsat ETM+ (2000, spatial resolution – 30m) [downloaded from Global Land Cover Facility, http://www.landcover.org] and LISS-III Multi-spectral (2004, spatial resolution – 23.5m) procured from NRSC, Hyderabad, India. Google Earth data (http://earth.google.com) served in pre and post classification process and validation of the results.

Environmental data such as precipitation of wettest month were downloaded from WorldClim – Global Climate Data [http://www.worldclim.org/bioclim]. Other environmental layers (Aspect, DEM, Flow accumulation, Flow direction, Slope, Compound Topographic Index) used for modelling landslide were obtained from USGS Earth Resources Observation and Science (EROS) Center based Hydro1Kdatabase [http://eros.usgs.gov/#/Find_Data/Products_and_Data_Available/gtopo30/hydro/asia]. The global LC change maps were obtained from Global Land Cover Facility, Land Cover Change [http://glcf.umiacs.umd.edu/services/landcoverchange/landcover.shtml; http://www.landcover.org/services/landcover change/landcover.shtml]. The spatial resolution of all the data were 1 km. 125 landslide occurrence points of low, medium and high intensity were recorded using handheld GPS from the field and published reports.