Study on different forest management measures on the water yield

The water balance of the vast beech woods in the Kasilian catchment in the northern region of the Alborz Mountains in Mazanderan in Iran south of the Caspian Sea is estimated from long-term precipitation and runoff measurements. This balance together with some field experiments were the base for the calibration and verification of the simulation Model “SIMWASER_WALD” by which the effects of different forest management measures upon the water yield in the Kasilian catchment are estimated by variation of either the tree population and density or of soil conditions due to trampling by sheep and cattle. Results show, that replacing the autochthonous beech woods by spruce and/or pine forests will decrease the water yield by 70% from 190 mm/a to only 60 mm/a. Forest grazing will reduce infiltration by soil trampling and therefore increase runoff peaks as well as reduce water supply of the trees. The simulation study shows, that the beech forests at the mountainous ranges of the northern Alborz are best guarantee for long term and sustainable water supply of the intensive cultivated lowland areas at the Caspian seashore and therefore should be managed according to the respective plans of the Iranian Forest Department.

Keywords:

evapotranspiration , water yield , Interception , water balance , Forest hydrology