Water Resources of Karnataka

Karnataka is located in the Deccan Peninsular region of India and covers an area of 191,791 square km. Water resources of Karnataka primarily constitutes surface and groundwater. Rainfall is the basic source of water in the state.

Availability of water resources in Karnataka

Surface water is available in Karnataka in the form of rivers, lakes, waterfalls, reservoirs, etc. Karnataka has surface water potential of around 102 km. Being the seventh largest state in India (area-wise), Karnataka possesses about six percent of the country’s total surface water resources of about 17 lakh million cubic metres (Mcum).

Karnataka is blessed with seven river basins. There are 36,753 tanks in the state and they have a capacity of about 684518 hectares. The rivers, along with their tributaries, account for much of Karnataka’s surface water resources. About 60 percent of the state’s surface water is provided by the west flowing rivers while the east flowing rivers account for the remaining portion. The annual average yield in the seven river basins of the state is estimated to be around 3,475 TMC. The yield in the six basins, excluding the west flowing rivers is estimated to be 1,440 TMC.

The seven river basins in Karnataka are:

1. Krishna
2. Cauvery
3. Godavari
4. West flowing rivers
5. North Pennar
6. South Pennar
7. Palar

Karnataka has groundwater resources estimated to be around 485 TMC. Ground water resources have not been exploited evenly across the state. In areas where adequate surface water is available, exploitation of ground water resources is minimum. Exploitation of ground water in the dry taluks of North and South interior Karnataka is higher as compared to Coastal, Malnad and irrigation command areas of the state.

Rainfall in Karnataka

Karnataka primarily enjoys a tropical climate that is largely dependent on its physio-graphic and geographic location with respect to the Arabian Sea and the monsoons. The state receives the benefit of two monsoons: the North-East monsoon and the South-West monsoon. Karnataka receives mean annual rainfall of around 1,355 millimeters. More than 73 percent of this rainfall is received due to the South-West monsoon.

The state can be earmarked into three meteorological zones, namely, North Interior Karnataka, South Interior Karnataka and Coastal Karnataka. The occurrence and distribution of rainfall in the state is not uniform.  The region that receives the maximum rainfall is Coastal Karnataka. It gets an average annual rainfall of 3,456 mm. South Interior Karnataka receives only 1286 mm average rainfall while North Interior Karnataka receives the least rainfall with 731 mm average figure annually.

Stressful situation of water resources in Karnataka

Though Karnataka enjoys a substantial amount of rainfall and has a significant quantity of water resources, it is not enough to meet the ever-increasing water requirement of the state. Karnataka suffers repetitive droughts. In spite of the availability of water from the river systems and tanks, Karnataka faces the serious issue of 67 percent of its land marked for irrigation falling under dry tracts.

With a rapidly increasing population and improved living standards, the pressure on the water resources is constantly on the rise. The per capita availability of water resources is reducing day by day. The erratic behaviour of rainfall and the Inter-State River Water disputes aggravate the problem. The impact of climate change on the water resources also cannot be ignored. Siltation of water bodies, misuse of resources, poor management of catchment area, all add to the stressful water resource situation in the state.

Groundwater is the major source of drinking water in Karnataka. Over 90 percent of the drinking water supply schemes in the rural areas of the state are based on ground water. This over exploitation is causing the fast decline of ground water resources in the state. The result is the scarcity of safe drinking water across many parts of Karnataka.

In order to cater to the water requirement of the expanding population, the existing water resources must be conserved and prevented from further degradation and depletion. Judicious and economic use of water resources for agricultural, industrial and domestic purposes can help in solving the problem to a large extent.