Estimation of Groundwater Recharge under various land ... - RMZ

Estimation of Groundwater Recharge under various land covers in parts of ...183ward is that, what happens to wateryield when the headwater catchmentsare planted with monoculture species.There are only limited studies carriedout to evaluate the hydrological impactsof plantation. In India, during thelast few years, considerable effort hasbeen made to understand the impact offorest degradation on the soil hydrologicalregime. However, studies arequite limited as far as the impact of forestdegradation on groundwater regimein western ghat region.The Western Ghat region is the originand primary catchment of many rivers(west and east flowing) in peninsularIndia. The lives of the majority of therural population in the four southernstates (Kerala, Tamil Nadu, AndhraPradesh and Karnataka) plus parts ofMaharashtra are thus critically dependentupon the watershed services providedby the Western Ghats forests.The portion of the Western Ghats thatlies in Karnataka state, contains themajor portion of the forests. It is reportedthat, there has been an increasedanthropogenic activities in the westernghat mountain region, a rapid change invariety of land-use and land cover aretaking place, which could have verysignificant impact on the water regimeof the region, which includes the baseflowand groundwater recharge.In the present study is an attempt tounderstand the impact of the land-us-es on the groundwater recharge underdifferent rainfall regimes with changein land-use conditions. In order to facilitatethe analysis, SWIM (Soil Waterand Infiltration Movement) model ischosen. It is selected in view of its simplicityand use of input parameters (soilmoisture characteristics) that can be directlymeasured in the field/laboratory.Materials and methdsStudy AreaUttara Kannada is a district with an areaof 10,291 km 2 , with its administrativeheadquarters at Karwar (Figure 1). Themain geographic feature of the districtis the Western Ghats (WG), which runsfrom north to south through the district.Between the WG and the sea is narrowcoastal strip, which varies from 8 kmto 24 km in width. Behind the coastalplain are flat topped hills from 60 m to100 m in height, and behind these hillsare the ridges and peaks of the WG.East of the WG is the upland, part ofthe vast Deccan plateau.In the WG region, majority of the rainfalls during June- September., i.e.,south-west monsoon. More than 90 %of the annual rainfall occurs during thefour monsoon months, with an averagenumber 120–140 rainy days per year.During the monsoon, a major portionof the rainfall is contributed by fourto five spells each lasting 8–10 days.RMZ-M&G 2010, 57