National 7 (Spotlight Weekly)

Alternatives Suggested

A section of experts believe that rainwater and ground water in Kathmandu valley could be sufficient to cater to the demand of the users

By A CORRESPONDENT

At a time when the residents of Kathmandu valley have already started to face scarcity of drinking water with the advent of dry season, some water experts have said that the underground water is sufficient to the population and feasible for use.

According to Ishwar Raj Onta, an engineer who has spent several years in the study of feasibility of the use of ground water in Kathmandu, up to 175 million liters of clean water can be extracted from deep tube wells without causing any adverse effects to the environment. This is ample amount to meet the demand of water of residents of Kathmandu valley, who at present get only about 90 Million Liters per Day (MLD) of water in the dry seasons and 120 MLD in wet seasons. The total demand for water for the present population of Kathmandu of almost two million is estimated to be about 150 MLD.

Revealing his findings, Onta also suggested that extraction of ground water is much more cost effective than alternate options that we have sought at present. "The cost for one deep tube well is about Rs. 10 million. We need to construct about 70 deep tube wells to meet the demand of the users," said Onta. "And this amount (700 millions) is almost 50 times cheaper than the amount proposed to be spent for Melamchi Drinking Water Project (MDWP) that has been taken as a mid-term solution to the water problems of Kathmandu Valley." MDWP plans to supply 170 MLD of water in Kathmandu, which is less than the amount that can be extracted from underground safely.

"Even with the successful operation of MDWP, the extraction of ground water is imperative as the demand of water will become much more than the present demand. The per capita use of water as well as the population of Kathmandu is increasing at a high rate," said another advocate of ground water.

At present there are 363 existing deep tube wells in the valley, of which only 31 are operational. These tube wells, most of them under the ownership of Nepal Water Supply Corporation (NWSC) covers fifty per cent of the water supply to Kathmandu. In addition, the number of dug (shallow) tube wells have increased largely in the recent years after Kathmanduites started facing acute scarcity of water in dry season. Individual households and companies, who have dug the shallow tube wells, however, are not satisfied with the poor quality of water that the wells pump out. Unlike water from deep tube wells, shallow tube wells do not supply bacteria free water. That is one of the reasons that such tube wells are used only at times of water crisis.

Onta agrees that ground water (drawn from deep tube wells) contains manganese and iron, which leaves some stains on clothes and tiles, but claims that it is safe for drinking and other domestic purposes if properly designed and maintained. "Deep tube well water is bacteria free, but due to improper construction and maintenance of the tube well water extracted in some places of Kathmandu valley is found to be contaminated," explained Onta. "The water from shallow tube well is contaminated and because of the leakage of this water from the upper surface the deep tube well water is also contaminated."

Geologists argue that over extraction of underground water is causing depletion in the water table causing adverse effect to the environment. However, there has been no study done about it. "If there is no problem in extracting millions of barrels of oil from under the ground in some places, why would there be problem in extracting water," argues researcher Onta.

Kathmandu gets ample rainfall every year and this rainwater seeps to the ground and the water table is recharged in due course of time. According to Onta's study, the water level in shallow tube wells have declined considerably, but has also recovered in two to three years. Likewise, there has been no heavy decline in the water levels in tube wells deeper than 200 m.

Of the total 620 square kilometers area of Kathmandu valley, it has a drainage area of 530 square kilometers. The study shows, from this wide surface a total of 81,000 million liters of water is recharged, i.e. seeps into the ground. If 150 MLD of water is extracted from the ground as per the demand, it amounts to only about 55,000 million liters in a year, which is well below the amount of water recharged.

Although, construction and use of deep tube wells at individual level is not feasible as it costs too high for an individual, its use can be promoted through local governing bodies like ward offices and VDCs and also by forming co-operatives at citizen level, opines researcher Onta.