How does a forest area affect the process of river discharge?
The greater the area of forest the less water in the river. Forests increase annual water yield? The general assumption is that total water supply, or river flow, to areas downstream from forested areas is higher than from alternative land use areas. Total river flow is dependent on the balance of a large number of hydrological factors. In theory, forests may be associated with a greater capture of atmospheric moisture, especially where cloud forests are involved. Natural forests usually maintain high infiltration rates and water storage capacity of the soil which reduces river flow in the early part of the rainy season before the whole landscape becomes saturated with water. Various studies in Vietnam showed a lower annual water yield when forest areas were compared with areas under agricultural crops with the same rainfall regime (Nguyen Ngoc Lung & Vo Dai Hai 1996; Thai Phien & Nguyen Tu Siem 1994). One study, for example, indicated that run-off under forests was 2.5 – 27 times smal
