To save the river from drying up, local water authorities in Guilin, a famous tourist destination in the Guangxi Zhuang Autonomous Region, plan to build three reservoirs.

    They will be situated on the upper reaches of the river to store surplus water in the flood season and replenish the river in dry periods.

    However, the plan, which is expected to take three years and cost 1.8 billion yuan (US$217.6 million), encountered harsh opposition from several environmental experts when it was put on the table late last year, the People's Daily reported.

    Critics said the construction of the reservoirs could not supply enough water, and may devastate the local ecology.

    According to local tour guides, the river has been suffering from very serious water shortages in recent years. Leisure boats' keels could often be heard grating against the riverbed in shallow water late last year.

    They said the boat ride down the river from Guilin to Yangshuo has had to be shortened by 20 kilometres from the original 83 kilometres. Some of the navigable stretches were even reduced to as little as six kilometres.

    But why such a water shortage?

    Environmental experts hold different opinions.

    Some say human encroachment is the main cause; they say mankind is chopping down too many trees at Mao'er Mountain, where the river originates.

    Statistics from the local forestry department show the forests on Mao'er Mountain, which covered 40,000 hectares in 1958, had shrunk to 17,700 hectares by 1980.

    Reforestation projects in the following decade helped raise the figure to 30,800 hectares, but the new trees cannot undo all the damage.

    The land was badly eroded, and its capability of conserving water seriously weakened. As a result, the dry season is longer and longer, said experts.

    However, others think natural factors such as scant rainfall in the dry season is the main reason for the recent water shortage.

    The flood season in Guilin runs from March until August, during which 76 per cent of the year-round precipitation occurs.

    These experts say droughts have happened many times in history, but at those times, the forests of the Mao'er Mountain were kept intact.

    "Forests cannot solve the problem of redistributing water. The only way to solve the water problem is to build reservoirs," said Liao Shijie, a former engineer with the region's Water Resources Department.

    Mo Tingjin, director of the Guilin Water Resources Bureau, said the three planned reservoirs, with a total storage capacity of 487.5 million cubic metres, could not only control flooding but also refill the river in the dry season.

    However, critics said large-scale construction on the upper reaches of the river will damage the natural environment and inundate the famed karst topography along the banks of the river.