Underground water supply
The valley's precious groundwater is threatened by indiscriminateand wasteful exploitation and contamination
FROM ISSUE #29 (09 FEB 2001 - 15 FEB 2001) | TABLE OF CONTENTS
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After the long dry winter and another three months before the monsoon sets in, water has once again become a major concern for the Valley's growing population. "Now that the dry season is approaching, the situation is going to get worse," says Thamel resident Smriti Bhattarai. Even though Bhattarai is connected to the Nepal Water Supply Corporation (NWSC) distribution network, there are times when she doesn't get water for days at a stretch. "When we do, it is so regulated that supply is not adequate at all." A shallow tube-well and an open well fulfil Bhattarai's drinking and household needs.
A couple of blocks away, Tashi Gurung has given up on the NWSC altogether. "We use groundwater pumped from a tube well dug a couple of hundred feet deep. All the houses in this area do." He attributes a slight depression in the ground floor of his four-storey home to excessive pumping of groundwater.
Experts say the same could happen to Kathmandu itself-the aquifer system will be exhausted, causing ecological disaster and potential land subsidence. Already the rate of extraction in excess of recharge has caused the water table to drop at an average rate of 2.5 metres a year. The first groundwater extraction was carried out by the Nepal Water Supply Corporation in 1970, and increased extraction in the Valley began in 1984 at 9 million litres per day (mld). By 1987, it quadrupled from 9 mld to 34 mld, and by 1998 the extraction of the Valley's groundwater, withdrawn through deep tube-wells, shallow tube-wells, stone taps, open wells and spring sources reached 42 mld-five times the 1984 level. While a World Bank Study in 1994 indicated that total sustainable withdrawal of groundwater from the Valley's aquifers is approximately 26.3 mld, a 1999 ADB study says total groundwater currently extracted is about 58.6mld-overexploitation by 60 percent.
Nepal Water Supply Corporation NWSC is one of the largest users of the Valley's groundwater. To meet the needs of a parched Valley, the NWSC pumps nearly 42.3 mld (78.3 percent). Hotels in the capital extract a little over 8.4 percent of this (10 mld), industry, 7.9 percent and the government 5.3 percent. A study conducted by the ADB also discovered over 300 tube wells, both deep and shallow, owned by the Nepal Water Supply Corporation and the private sector. Added to this is a rapid increase in private tube-wells, installed to augment water supply to Valley households.
Declining forest area and increasing urban built-up area are responsible for diminishing recharge capacity in the Valley. A 1990 JICA report, on the basis of a simulation model, calculated the recharge rate to be 27,000 mld, slightly less than the earlier estimate of 30,000-40,000 mld. Despite recharge occurring mainly in the northern groundwater districts, the percentage remains low owing to the geological nature of the area. As upper deposits of the central and southern aquifers are thick layers of impermeable clay, recharge capability is much lower in these areas. The rate of depletion of the water table is more pronounced-and alarming-in the northern well fields of Bansbari and Manohara where the NWSC carries out extensive pumping to meet the city's needs.
Another indicator is the drying up of stone spouts. Two dozen of the city's historical spouts are dry, and the water level at Rani Pokhari, Sundhara and Panchdhara are seriously affected-some directly by NWSC wells.
It is common knowledge that groundwater should be used judiciously, to ensure a balance between long-term demand and natural replenishment. Groundwater experts are therefore keenly awaiting the enactment of a legislation governing the extraction of groundwater currently being drawn at the initiative of the Water Resources Ministry. "It may not be in time for this session of Parliament. But it will definitely be ready for the next session," says Dinesh C Pyakural, Executive Director of the Melamchi Water Supply Project. The legislation being drafted addresses the need to control private extraction of groundwater through licensing, tariffs and regulation.
The $464 million Melamchi project, which plans to bring in piped water from the Melamchi Khola by 2006, is especially keen that the legislation regulates private extraction of the Valley's depleting groundwater supply. Once the licensing of groundwater extraction is made mandatory, it would become a sound source of water supply for a privatised NSWC (one of the preconditions set by donors of the Melamchi project). Adequate supply will then ensure that the Corporation will win the confidence of consumers before Melamchi water is piped in.
"During the pre-Melamchi phase, a nominal fee would ensure that consumers make judicious use of the Valley's groundwater, which could then be used to augment supply in the dry season," says Pyakural. Post-Melamchi tariffs, he says, will reduce the rate of extraction. It would discourage use of groundwater-a precious reserve-when a privatised NWSC has an adequate supply. "It makes economic and financial sense that the project should recover half of $464 million that donors have invested," says Pyakural.
At present consumers pay Rs 8 for every 1000 litres of water supplied by NWSC. But when you add the debt service, the depreciation, the costs of boiling and filtering water, and medical costs, it reaches Rs 16 per 1000 litres. In addition, the NWSC hasn't been able to fulfil consumer needs in specific areas.
Melamchi's water, at Rs 24 per 1000 litres, would ensure safe, reliable, and regular supply of drinking water, says Pyakural. The project plans to launch a public awareness campaign as part of its comprehensive policy for sustainable use of water resources. The project is carrying out a pilot feasibility and appropriate technology study for enhancing groundwater storage by artificial recharge in Manohara. The absence, however, of defined aquifers makes it a complicated process, say experts. Limestone and non-developed alluvial areas around the Valley are being checked as potential additional groundwater resources, but there's been no positive finding so far.
Also at risk is the quality of groundwater. At the behest of the MWSP, a team from the Irrigation Department has been monitoring the quality of groundwater in 50 wells around the Valley for the last year. "About 60 percent of the water from shallow wells is contaminated," says Mohan Singh Khadka, senior divisional chemist at the Groundwater Division, Department of Irrigation. "Most water samples from stone taps and open wells were found to contain faecal matter and high numbers of coliform bacteria."
While deep aquifers are relatively unpolluted, they contain high levels of iron and manganese, which means the water has to be treated before use. "We should refrain from using water from deep aquifers. It's a precious resource that should be stored protected from contamination. Once groundwater is polluted, it will take years, probably hundreds of years, to restore its original quality," says Jeevan Lal Shrestha, Project Chief, Groundwater Resources Development Project. More simple and cost effective, say experts, would be to reuse treated wastewater, harvest rainwater and not waste water.