Study On The Effect Of Rainfall Interception By A Canopy

Studies on rainfall interception of forest canopy not only have the hydrology significance, but also have the important ecological significance. When we study on the problem of forest canopy intercepting rainfall, the canopy interception and interception percentage used to be the index of the canopy interception capacity is proposed recently.This paper focuses on introducing the concept and the method to measure of canopy interception capacity and evaluating the effect of rainfall interception of a deodar cedar tree on the campus of the Shandong Agricultural University and natural forest of Changbai Mountain and plantation of east Liaoning, and comparing the characteristics and the effects of evaluating the interception of the three indexes. In addition, empirical model and the semi theoretical and semi empirical model of the canopy interception capacity are established and whose rationality and applicability are verified. In this paper, the following conclusions can be concluded:(1)The canopy interception capacity is the canopy interception under the ideal state, The relationship between the rainfall interception capacity and rainfall are examined by taking the maximum under the same rainfall and presented by the envelope of the measured a series of data. the interception capacity not only can fully reveal the ability of rainfall interception by forest canopy but also can be used to compare the abilities of different forest-stands.(2)The rainfall interception capacity is in line with the general law of rainfall interception. When the precipitation is lower, the effect of rainfall interception increases with precipitation increasing; when the precipitation increases to a certain value, the canopy has been to saturation and the effect of rainfall interception reaches the maximum value and tends to becomes stable.(3) By the analysis and comparison we can conclude that the rainfall interception capacity of the plantation forest is higher under low rainfall less than 28 mm, and it increases much more rapidly; the rainfall interception capacity of the natural forest is lower under low rainfall less than 30 mm while it is higher under heavy rainfall more than 28 mm, and that the saturation interception capacity of the natural forest is larger. In addition that if the spatial distribution of the canopy is more uniform, the speed of reaching the saturated interception capacity is faster; the saturation interception capacity(the maximum interception capacity of the canopy) related to the total amount of the foliage and the larger amount of the foliage has the larger saturation interception capacity.(4) The relationship between interception capacity and rainfall can be expressed with function formula and whose parameters reflect the characteristics of the canopy. Established experience model and semi theoretical and semi empirical model are in according to rainfall interception capacity. The parameter K in experience model can reflect the relationship between the curvature of the curve, which is determined by the uniform degree of the distribution of the canopy; and the parameters of I0 presents the saturation interception, which depended on the amount of the foliage in the canopy. The parameter of W in the semi theoretical and semi empirical model reflects the saturation interception capacity, which depended on the amount of the foliage in the canopy; the parameter of H reflects the perception with the canopy reaching saturation; the parameter of β determined by the value of W and H.