ABSTRACT

Landscape structure plays an important role in the functional aspects of an ecosystem, which include hydrological and bio-geo chemical cycling. Alterations in landscape structure with the irreversible land use changes have influenced the surface water and groundwater hydrology. Anthropogenic activities due to unplanned developmental activities to meet the growing demand of burgeoning population in developing world have accentuated deforestation, etc. Current communication focuses on quantifying land use dynamics and hydrological parameters in Sagra taluk, Shimoga district, Karnataka. Sagara taluk topographically consists of Ghats in the west and the plain-lands towards the east with rainfall varying from 1500 mm near the plains to over 4500 mm towards the Ghats. Land use analysis between 1973 and 2012 shows that horticulture (plantation) has increased from 10.7% to 37.2% whereas forests have decreased from 57.3% to 42.5% in 4 decades. Ghat portion i.e., western portion of Sagara was dominated by forests and horticulture (Areacanut, Banana, Ginger, etc.), whereas the plains in the east were dominated by agriculture (Paddy, Jowar). Hydrological investigations were carried out for 16 months covering all seasons during 2014 and 2015 in the select catchments of Sharavathi and Varada river basins. The study results reveal that (i) ground water fluctuations vary from <0.6m (along the downstream of lakes with good forest cover) and 1.2m (with good forests in the upstream) to 1.5 m (in the catchment dominated by degraded forests), (ii) perennial streams occur in pristine forests as forested catchment aid as sponge and retains the water during monsoon and steadily releases in the lean seasons. The analysis of regional hydrology with landscape dynamics provided insights to the role of forests with native vegetation in sustaining the water in streams and lakes. This also helped in understanding watershed management strategies to sustain and maintain desired environmental flow, while catering to domestic and agricultural demands.

Keywords: Landscape dynamics, Land use, Hydrology, Remote Sensing data, Spatial analysis.