On the simultaneous utilization of four kinds of water in Linshan Commune

Joint group for study of ecology of farmland in rolling area in M.Sichuan

The 4 kinds of water are:surface runoff, groundwater, moisture held by the soil and cutting down of water demand by way of utilizing the thermal and hydrological effect of forest belts. It has been estimated that a reduction of 3% of water consumption in moderately dry year through forest belts in Linshan Commune in Yanting county in Sichuan province was manifest, and 379.500m" of water detained in reservoirs and other water conservancy works are available for use together with another 264,000m' from beneath the ground surface.Detention of water in paddy fields and ponds and runoff available in the growth period make up for another 280,000m3. The total demand of water for the commune is 2.629 million m8/ year,from which 79,100m3 are to be deducted due to effect of forest belts, the remaining being 1.78 million m3 for dry crops and 0.76 million m8 for paddy field. Besides moisture held in soil, detention in paddy fields and ponds in winter and runoff made use of during the growth period,234,400m8 are to be provided for dry crops and 483,300m8 for paddy fields.Simultaneous utilization of surface and underground reservoirs will be able to ensure the demand of water for paddy field and for dry crops in spring until the month of June, when water will again be deficient for use of the dry crops.