东北黑土区北部典型小流域融雪径流及发生条件分析

Analysis of snowmelt runoff and its formation condition in typical small watersheds in the northern black soil region of Northeast China

为了研究黑土区小流域尺度融雪径流及发生条件,利用2005—2015年黑龙江省鹤山农场鹤北小流域把口站春季融雪径流资料和气象站日气温、降雪资料,建立融雪初日的有效积温公式,采用回归方法分析春季融雪径流深与降雪量和秋季降雨量的关系,有效积温与降雪量的关系,并探讨本研究区融雪径流发生的条件。结果表明:1)研究区内小流域春季融雪径流初日多发生于3月下旬至4月上旬,近10年平均融雪径流深为11.9 mm,发生融雪径流的年份,冬半年累积降雪量增加1 mm使春季融雪径流深增加0.9 mm;2)小流域春季融雪径流深(D)可以用冬半年降雪量(P s)和8—10月降雨量(P r)拟合,其关系为D=0.91P s+0.034P r-21.02,冬半年累积降雪量和8—10月降雨量满足D>0时,才发生融雪径流;3)在累积降雪量达到融雪径流发生的前提条件下,融雪径流发生初日前期稳定通过界限温度-2.8℃的积温T A(℃·d)与冬半年累积降雪量(P s)的回归关系为:T A=18.29 ln(P s)-10.78。研究结果可为该区小流域融雪径流快速预报及农业生产提供科学依据。

[Background]The forecast and formation condition of snowmelt runoff is very significative to understand the process of snowmelt erosion in the northern black soil region of Northeast China.Many studies have focused on the characteristics of snowmelt runoff,however,and the study on the formation condition of snowmelt runoff is deficient.[Methods]Based on the observed data of two small watersheds located in Hesan Farm,Heilongjiang province,the formula of effective accumulated temperature on the initial day of snowmelt is established,regression method was used to establish the functional relationship between snowmelt runoff depth and accumulated snowfall in the winter half year and accumulated rainfall in the autumn,and the functional relationship between effective accumulated temperature and snowfall.The occurrence conditions of snowmelt runoff were established by the above equations and indexes.The data include the daily temperature and snowfall of weather station located in the Hebei watershed from 2005 to 2015,and the spring snowmelt runoff of 2 weirs of small watersheds from 2005 to 2015.[Results]1)The initial days of spring snowmelt runoff in the small watershed in the study area were mostly from late March to early April.The average snowmelt runoff depth of the study area was 11.9 mm from 2005 to 2015.In the year of snowmelt runoff,an increase of 1 mm in accumulated snowfall in the winter half year resulted in an increase of 0.9 mm in snowmelt runoff depth.2)The regression equation between the snowmelt runoff depth D(mm)in spring and the accumulated snowfall in winter half year(P s)and August-October rainfall(P r)was D=0.91 P s+0.034P r-21.02.Snowmelt runoff occured when both must meet D>0.3)Under the precondition that the accumulated snowfall reached the snowmelt runoff occurrence,the relationship between accumulated temperature(T A)above the thereshold temperature(-2.8℃)before snowmelt runoff occurred,and the accumulated snowfall in the winter half year(P s)was regressed by a logarithmic function:T A=18.29ln(P s)-10.78.[Conclusions]Whether snowmelt runoff occurs depends on accumulated snowfall in winter half year and accumulated rainfall in August to October.The snowmelt runoff depth can be expressed by a linear equation of the accumulated snowfall and rainfall.The initial day of snowmelt runoff occurrence can be calculated by threshold accumulated temperature.This study will help to forecast snowmelt runoff and guide agricultural production.