Sayhadri Conservation Series 45  
ENVIS Technical Report: 82,  November 2014

Water Scarcity in Varada Catchment: Need to arrest Deforestation on Priority

Ramachandra T.V.                Subash Chandran M.D..                Vinay S                Bharath H. Aithal              

Energy and Wetlands Research Group, Centre for Ecological Sciences, Indian Institute of Science, Bangalore – 560012, India.
*Corresponding author:

Water is an essential source of energy for all life forms on the planet and many a times managing this resources to meet the human needs has failed due to anthropogenic activities. Hence it is necessary to understand the relationships between the elements contributing to the water yield. Yield of water resource in any catchment is dependent upon various characteristics such as topographic, geologic, land use, meteorological criteria’s, and so on.

Topographic conditions include the elevation, slope and drainages; the slope towards the plains is flat, where as they are high and variable towards the Ghats, these terrain features gives rise to the various drainage conditions such as dendritic drainage pattern, parallels and so on. The relation between the elevation, slope and the drainage can be established, example: higher variation in the altitude of the terrain would lead to higher slope variations in turn leading to higher density drainage network, higher drainage density locations indicate the Ghats whereas low density drainages indicate the plains. Along the plains due to depression in the terrain (natural/artificial), lakes are formed/created which are inter connected to each other through the surface and subsurface water network and thus storing water.

The geological criteria’s includes the texture, structure, and other factors of rocks and soils. Rocks or soils based on their parent material have the capacity to absorb, store and release water with seasons, example: sandy soils have the ability to allow water to completely percolate but lack storing capabilities, granitic rocks since they have low pore spaces does not readily absorb water but allows slower rate of percolation, clay soils have ability to trap water for a longer duration but doesn’t allow complete percolation of water. The available water as the soil water helps in agricultural activities; water in the vadose and ground water up to the hypomorphic zone allows flow in streams. 

Land use of a catchment with various other parameters and factors defines the water availability and the water needs. Land use Land cover (LULC) dynamics is a major concern, as the abrupt changes has a negative impact on ecology, climate, hydrological regime, and also people’s livelihood in the region. LULC dynamics are specific to a region and vary from region to region. Land Cover refers to the observed physical cover on the earth’s surface. Land cover essentially distinguishes the region under vegetation with that of non-vegetation. Land use refers to use of the land surface through modifications by humans and natural phenomena. Land use in a region are classified into various classes such as water bodies, built up, forests, agriculture, open lands, sand, soil, etc. Land use modifications alter the structure of the landscape and hence the functional ability of the landscape. The modification includes conversion of forest lands, scrublands to agricultural fields, and cultivation lands to built-up, construction of storage structures for water bodies leading to submergence of land features that may vary from small scale to large scale. Landscape is heterogeneous land area of interacting systems which forms an interconnected system called ecosystem. The functional aspects (interaction of spatial elements, cycling of water and nutrients, bio-geo-chemical cycles) of an ecosystem depends on its structure (size, shape, and configuration) and constituent’s spatial patterns (linear, regular, aggregated). The status of a land cover can be visualized using the LULC information which provides a base for accounting the natural resources availability, vulnerability and its utilization, example: decline in natural forest would lead more water draining off during monsoons, impacting on the hydrological regime of the catchment, forest land use has higher capability to infiltrate the precipitated water and store it in the sub strata’s thus providing resource during post monsoon. This information pertaining to LULC provides a framework for decision making towards sustainable natural resources management.

Meteorological conditions play a major role along with other factors as discussed above in order to cater the water. Precipitation plays a major role in describing the water availability during a year; lower precipitation would lead to drought like conditions, whereas high and intense rainfall would lead to flash floods (w.r.t land use, topography, geology). Temperature, humidity, wind helps the water to evaporate/transpire from various land uses at different rates across seasons which helps the water bearing clouds to recharge during post monsoons. The rate of agriculture, cropping pattern and sowing time depends on the monsoon conditions. Other factors include domestic water demand, livestock water demand, etc.

The above criteria’s that play a major role in define the water yield can be identified/estimated using Remote Sensing and GIS. Satellite remote sensing technology provide consistent measurements of landscape, meteorological condition, allowing detection of both abrupt changes and slow trends over time for managing natural resources. Remote Sensing (RS) data with Geographic Information System (GIS) and Global Positioning System (GPS) helps in effective measure of landscape dynamics in cost effective manner.
Varada is a north flowing river that originates at Varadamoola (Annexure 1) of the Western Ghats. The stream course had given birth to civilizations, such as kingdoms like Keladi. The river due to its sanctity owns its place in the literatures (vedas, puranas, etc.). Similar to any other neglected river coarse, river Varada and its catchment is also being mismanaged and ignored. Once a perennial river has now degraded to a seasonal river, depriving of the water resource to the dependent functional aspects such as agriculture, forest, domestic, animals and many more. The catchment encompasses several protected forest (sacred groves / kans) which are in many cases degraded for various purposes such as household, fuel wood, fodder etc. The kans attribute to adding of water resource into catchment post monsoon. The degradation of kans has led to depreciation in the water yield in catchment, and leading to serious water related issues in terms of domestic, agricultural, and other needs.

The objective of the study is to understand (i) land use variations with time (ii) water yield in the Varada catchment in Sagara taluk of Shimoga district in relation with the land scape dynamics, metrological variations and other depending factors, in order to identify the demands based on various needs. This work helps in identifying the ability of the sub catchments of Varada to cater the water demands within them, the study also helps to identify the locations which have deficiency of water which would also help planners to identify the reason, and plan for the management of this resource without damaging the natural ecosystem.

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