Based on published hydrological data, runoff and sediment were calculated for evaluating units by dividing the study area into hydrological polygons, combining hydrological data with the hydrological polygons map, setting up the accumulative relationship between subcatchments and validating the runoff and sediment dat.

Taking 2000 as the level year,five calculation units as Xidahe irrigation district,mountainous water irrigation district of Liuhe middle stream,well and spring irrigation district of Liuhe middle stream,Hongyashan irrigation district and Dajinghe system were divided,combined with the distribution of water systems.

Thatis tree grid molel based on the computing unit of enterprises and institutions,the hinge node of province or city’s computingcenter or information center and the general node of national information center.

The imagine described tree tape grid model according to corporation and career is a computing unit, province and city s computing center or information center is a hinge node, national information center is general node.

In this paper,on the base of research result in the world,taking the example of hydrological computation in the work of some dam safety evaluation,the influence to the downriver reservoir from the upstream is discussed.

Based on the quantitative hydrological computations, this paper analyzes the drainage functions of the shallow dished ditches,space setup of water in lets,drainage functions,silting up of the dark buried ditches and the interact ions between them,and puts forward the general drainage design methods for the shallow dished dark buried ditches for reference.