Characteristic Of Rainfall Interception By Shrub In Tianlaochi Catchment In The Upper Reaches Of Heihe River

The water is the source of life and economic activities, especially in the arid region of Northwest China, there will be an oasis if it has water, there will be an desert without water.It is an important factor of economic and social stability in Northwest China. Heihe River is a typical inland river basins in Northwest. It plays an important role on regional development, the upper reaches of the heihe River basin has rich atmospheric precipitation, it is not only enough the ecological consumption water of vegetations in study areas, but also formation of basin water district, however, rainfall interception reduces the precipitation by vegetation. It is the focus of attention of scientists. It is focused on rainfall interception of forest ecosystems, however, the rainfall interception of shrub ecosystems is relatively rare. As the main vegetation types of Shrub in the upper reaches, has made important contributions to water conservation in the upper reaches.The study selected in the upper reaches of Heihe River basin as the study area and the typical shrubs(Dasiphora fruticosa, Caragana jubata) of research object, We developed an automatic measurement system to measure precipitation and interception. At the same time we collected data of leaf ecological parameters such as leaf area, leaf area index and specific leaf area during growing period.During growing period, a total of 65 effective rainfall events were observed with the gross precipitation of 311.6mm, The canopy interception of Dasiphora fruticosa was 95.23mm, accounting for 30.56% of total precipitation. The canopy interception of Caragana jubata was 69.25mm, accounting for 22.22% of total precipitation. Between precipitation, interception and interception percentage were exponential function relation.The leaf area, leaf area index and specific leaf area of Dasiphora fruticosa and Caragana jubata were changed during the growth. As follows of observation results, leaf area of Dasiphora fruticosa from 0.13cm2/piece to 0.70cm2/piece; leaf area of Caragana jubata from 0.23cm2/piece to 0.59cm2/piece; leaf area index of Dasiphora fruticosa from 1.23 to 4.3; leaf area index of Caragana jubata from 0.56 to 2.86, specific leaf area of Dasiphora fruticosa from 104.8cm2/g Caragana jubata from0.56 to 2.86; specific leaf area of Dasiphora fruticosa from104.8 cm2/g to 118.8 cm2/g, specific leaf area of Caragana jubata from 119.9cm2/g to 132.0cm2/g. These results indicated a significant change canopy parameters of shrub during growing period.We analyzed the variation of precipitation and interception in three special rainfall events which were happened on June 7th, July 6th and August 5th, which represented the initial stage, the middle stage and mature stage of shrub growth, respectively. We found saturated interception of Dasiphora fruticosa were 2.57mm, 4.65mm and 6.97mm and saturated interception of Caragana jubata were 2.82 mm,4.54 mm and 4.65 mm, respectively, corresponding to the three stages.we collected remote sensing, such as airborne LiDAR (Light Detection And Ranging) and high-resolution remote sensing image (Geoeye-1) to draw the spatial distribution of shrub rainfall interception.. The LiDAR data was used to obtain the spatial distribution of shrub height. Geoeye-1 data was used to retrieve the spatial distribution of shrub coverage. First, we got the spatial distribution of shrub aboveground biomass, In the study area the maximum aboveground biomass unit area is 691.8, the minimum value is 0.5; Second, according to establish the relationship between the aboveground biomass t and leaf area index, we could estimate the spatial distribution leaf area index in the study area, the maximum value of 5.7, the minimum value is 0.5; Finally we would obtain the spatial distribution of rainfall interception. the maximum rainfall interception is 133 mm, the minimum is 98 mm;The spatial distribution of rainfall interception rate between 30% and 36%.