The Hindu : Karnataka / Bangalore News : Krishna basin being bled dry

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Wednesday, Mar 19, 2008
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Karnataka

Karnataka - Bangalore

Krishna basin being bled dry

Nagesh Prabhu

Empty river: This May 2003 photo shows the dry bed of the Krishna in Belgaum district. There was almost zero discharge from the river into the ocean during 2001-04.

BANGALORE: The depletion of water in the Krishna river is changing the ecosystem in its basin, according to a recent research report.

A significant increase in the utilisation of water from the river for irrigation, with little regard to availability, has caused ‘closure of the basin’, meaning that there was zero or minimal discharge to the ocean during 2001-04.

Surface water resources were entirely used for human consumption. Increased groundwater abstraction contributed to the decrease in surface water base-flows, resulting in almost zero discharge into the ocean, revealed the report “Shifting Waterscapes: Explaining Basin Closure in the Lower Krishna Basin, South India.”

‘Unsustainable’

The report, authored by Jean Philippe Venot, Hugh Turral, Madar Samad and François Molle of the International Water Management Institute, Sri Lanka, stated that despite evidence of basin closure, the three States that share the Krishna waters continued to strongly promote their agriculture and irrigation sectors. “This development path can no longer be sustained without impinging on existing water use and affecting the security of supply for existing users,” it said.

In 2007, the basin population was evaluated at 79 million inhabitants with 51 million in rural areas. The total created water storage capacity reached about 51.5 billion cubic metres (bcm) in 2002. The basin has major irrigation and hydro-power projects such as Nagarjuna Sagar (built in 1967) and Sri Sailam (1983) in Andhra Pradesh; Bhadra (1953), Malaprabha (1973), Ghataprabha (1977) and Alamatti (2003) in Karnataka; and Koyna (1964) and Ujjani (1981) in Maharashtra.

First indication

The increase in the irrigated area (3.4 million hectares during 1996-2002) and groundwater abstraction for cultivation (1.5 million hectares during the same period) caused a decline in the discharge of water from the Krishna into the ocean, providing the first indication of river basin closure.

The Krishna basin (2,58,948 sq. km) is the fourth largest Indian river basin in terms of annual discharge and is ranked fifth in terms of basin area. The basin covers parts of Andhra Pradesh, Karnataka and Maharashtra. The Krishna originates in the Western Ghats in Maharashtra and Karnataka, drains the dry areas of the Deccan Plateau, and forms a delta before flowing into the Bay of Bengal.

Steady decrease

Before 1960, the river discharge into the ocean averaged 57 bcm a year. Since 1965, it steadily decreased at an average of 0.8 bcm a year to reach 10.8 bcm in 2000 and fell close to nil in 2004 (0.4 bcm). Only monsoon flows (July-October) reached the ocean, and peak outflows were delayed by about two months because of increased upstream regulation.

During 2005-07, the basin had high rainfall and the ocean discharge averaged 29 bcm a year. The area irrigated by groundwater almost doubled in 30 years, reaching about one million hectares during 1996-2002. This expansion occurred mainly in Maharashtra where the area under sugarcane increased substantially.

The lower Krishna basin is one of the first regions to be adversely affected by any hydrological changes that take place elsewhere in the basin, resulting in severe water shortages and spatial redistribution of water during times of drought, the report said. The main change that has affected the waterscape of the lower Krishna basin during the past 50 years is the decrease by more than half of surface water inflows into the lower basin (25.8 bcm a year during 1996-2000) due to water utilisation in the upper basin.

Need for options

The report said there was a need for options that preserved a balance between equity, sustainability and efficient use of scarce water resources for both human benefit and preservation of the environment. “This could be done through the definition and implementation of formal effective and adaptive water allocation mechanisms, within the framework of the present Krishna Water Disputes Tribunal in charge of apportioning the waters to the three States,” the report said.

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