Modeling rainfall canopy interception of Picea crassifolia forest in Northern Slope of Qilian Mountains:a case of Pailugou catchment

Canopy interception plays an important role in water circulation and water balance of ecosystems in the arid and semi-arid regions.At present,most research concentrates on the characteristics of interception in the scope of a stand or plot.Models of canopy interception in river basin or landscape scale based on RS and GIS are lacking because the factors influencing canopy interception such as precipitation,vegetation are difficult to be spatialized.Statistical model of canopy interception was improved based on investigation in the study area.Considering the important influence of canopy structure,LAI was added to the model.After parameters in the model were spatialized,the estimation of canopy interception was scaled up from the plot to the catchment using remote sensing data and GIS.The results show that the amount of canopy interception in the Pailugou catchment is between 97.9 and 236.6 mm,the mean interception amount 161.8 mm.The minimum interception appears at the lower altitude area and the maximum interception presents at the higher one.The interception percentage of Picea crassifolia forest in the Pailugou catchment is between 27.92% and 58.00% and increased at the beginning and then decreased along with the raise of altitude.The total interception was 1.6×105 m3 in 2008,only accounting for 13.25% of that year's precipitation.