Study On The Influence Of Topography And Geomorphology On Precipitation Over Tianshan Mountains, Central Asia

Precipitation in mountainous area is the most important part of the hydrological cycle, and also themomentous source of water resources in arid regions. The Tianshan Mountains is the unique mountains inthe world, due to its special geographical location and high altitude, it intercepts the water vapor carried bythe zonal westerlies, forming plentiful precipitation in the mountainous area. Futhermore, the spatialdistribution of the precipitation in mountainous areas is of heterogeneity, owing to the complex topographyand geomorphy. Therefore, the investigation of influence of topography on precipitation is of significance.We aim at the influence of topography on precipitation, taking the Tianshan Mountainous as researcharea in this research. Firstly, the TRMM3B43Version7monthly precipitation product is evaluated andvalidated based on42ground stations around the Tianshan Mountains. Secondly, the geomorphy andtopography features are extracted and analyzed according to the Digital Elevation Model. Thirdly, theinfluence of topography on precipitation is researched. Last but not least, two three-dimensional spatialinterpretation methods are conducted, taking the influence of topography on precipitation into account. Andthese methods are carried out and corss validated, taking35%of the TRMM precipitation grid as referencestations and the rest as stations to be estimated. Some conclusions have been researched as follows:(1) TRMM3B43V7product has a good availability and can be a replacement of precipitation inTianshan Mountains, especially for the regions higher than1500m.(2) Geomorphy types are dominated by low-altitude plain, middle-altitude platform, low-relief andmiddle-relief mountain. And among the topography features, elevation changes dramatically, relief variessignificantly, slope diversifies.(3) Geomorphy types influence the precipitation greatly, and the influence decreases as the geomorphytype lists as mountain area, hills, platform and plain. In terms of the mountain area, the precipitation inhigh-relief region is less than low and mid-relief region. Precipitation in Tianshan Mountains is primarilyaffected by longitude, latitude, elevation and relief. However, slope and aspect has less effect on it.(4) The improved inverse distance weighting (IDW) methods which introduce elevation and relief,including inverse distance&elevation weighting method (IDEW) and inverse distance&elevation&reliefweighting method (IDEWR), are better than the IDW method. In addition, the IDEWR method is betterthan IDEW method.