Snowcover Distribution Study and Snowmelt Runoff Prediction System of the Songhuajiang River Basin

1.基于分布式径流模型对1998年松花江洪水进行了径流分析，建立了全流域经纬度网格间距均为30 min的分布式径流模型。利用分布式水文模型对1998年历史洪水进行了模拟，成功地再现了该次历史洪水的洪水过程。2.1对松花江流域进行了积雪调查，结合已发表的报告，得到了积雪的分布情况。2.2利用分布式水文模型进行融雪径流分析。收集了拉林河和岗河的实测降水和径流资料，松花江的两条支流。通过对实测资料的统计分析，发现降水量随海拔高度的变化规律，建立了拉林河流域经、纬向网格间距均为90 min的分布式融雪径流模型。该模型运行的洪水流量和smwmelt径流。洪水流量计算结果表明，与实测值相比，计算的河流流量偏小。对于融雪计算，构造了一个新的模型来考虑日温度变化，以产生融化季节早期阶段的融雪径流。

1.River runoff analysis of 1998 Songhuajiang river flood based on the distributed runoff model.The distributed river runoff model with grid spacing of 30 minutes in both latitude and longitude directions is constructed for the whole basin of the Songhuajiang River, China. The model is run for the historic 1998 flood reproducing successfully the flood hydrograph of that event.2.1 The snow survey is conducted for the Songhuajiang River basin and, combined with the published reports, the distribution of snowcover is obtained.2.2 Snowmelt runoff analysis with the distributed hydrologic model.The measured data of precipitation and river discharge is collected for the Lalinhe River and Gang He River, both tributaries of the Songhuajiang River. The statistical analysis of the collected data shows the dependency of the precipitation on the altitude.The distributed snowmelt runoff model with the grid spacing of 90 min both latitudinal and longitudinal direction is constructed for the Lalinhe River. The model is run for both flood flow and smwmelt runoff. The result for flood flow shows that the calculated river flow tends to be small compared to the observed values. For the snowmelt calculation a new model is constructed to account for the diurnal temperature change to produce the snowmelt runoff for the early stage of the melting season.