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基于SWAT的积雪消融对高寒区农田土壤水分影响模拟

Simulation on Effect of Snowmelt on Cropland Soil Moisture within Basin in High Latitude Cold Region Using SWAT

  • 摘要: 为明确我国高寒区积雪消融对春季农田土壤水分的作用,针对气象站点监测数据、遥感及陆面模式同化数据在时空分辨率方面存在的不足,以地处黑龙江省中部的呼兰河流域为例,利用SWAT(Soil and water assessment tool)模拟流域降雪、积雪、融雪等过程,研究流域内降雪、积雪、融雪的时空变化特征及其对春季农田土壤水分的影响。结果表明:呼兰河流域的平均降雪量、最大日积雪量、融雪量空间分布呈现自西向东逐渐增加的相近特征;积雪量、降雪量、融雪量变化率的空间分布特征相近,这些变化率在流域内大部分区域呈现增长趋势;降雪量、积雪量、融雪量的年时间序列关系密切,与土壤水分的年际变化趋势相近,农田土壤水分的年际变化受降水量影响较大;上年11月至当年3月的各月积雪量、上年11月降雪量、当年4月融雪量与当年春季4、5月农田土壤水分含量的相关性较显著;融雪水在3月下旬至4月上旬补给土壤水分,能够促使农田土壤水分短期上升,积雪量决定了融雪水对农田土壤水分的补给作用;农田土壤水分在融雪前下降趋势平缓,但在融雪后急剧下降。

     

    Abstract: The objective was to clarify the effects of the snowmelt on cropland soil moisture in spring of the high latitude cold region in China. The Hulan River Basin, which locates at the middle Heilongjiang Province, was adopted as the study area. In consideration of the deficiencies of spatial and temporal resolution of monitoring station data, remote sensing data and land surface model assimilation data, the hydrological processes such as snowfall, snow cover, and snow melting were simulated using soil and water assessment tool(SWAT). Research on spatial and temporal characteristics of snowfall, snow cover and snowmelt and their effects on the cropland soil moisture in spring of the Hulan River Basin were carried out. The results indicated that the spatial distributions of the average snowfall, the maximum daily snow cover, snowmelt within the Hulan River Basin showed a similar characteristic that gradually increased from west to east; the change rates of snow cover, snowfall and snowmelt exhibited the similar spatial distribution characteristics and these change rates showed increasing trend at most areas within the basin; the close relationships existed among the series of annual snowfall, snow cover and snowmelt, that were similar to the interannual variation trend of soil moisture, and the interannual variation of cropland soil moisture was greatly affected by precipitation. A related significant correlation existed between the snow cover in a period from the last November to the current March, the snowfall in the last November, snowmelt in current April, and the cropland soil moisture in April and May of the current year. The snowmelt water recharged the soil moisture from the late March to the early April, which could promote the short-term increase of soil moisture, and the amount of snow cover determined the replenishment of snowmelt water to cropland soil moisture; the change trends of soil moisture were gently decreased before snowmelt, whereas significantly decreased after snowmelt ended.

     

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