甘肃旱作农业区降水对土壤水分的影响

 利用甘肃旱作区35个气象站1961—2007年日降水量和13个农业气象观测站从建站到2007年逐年4—10月旬土壤重量含水率资料,分析了旱作区土壤湿度与降水量的关系。采用REOF把甘肃旱作区年降水量划分为4个气候子区域:陇东、陇中西部、陇中东部和陇南。结果表明:①在0～100 cm各层土壤中,耕作层0～30 cm土壤湿度与降水量的关系最好。②旱作区降水量和耕作层土壤湿度存在着一致的年际振荡趋势。各地土壤增湿时间与旬降水达到20 mm的时间基本一致。③耕作层土壤湿度与降水量有极显著的正相关关系,土壤湿度对降水量的敏感性随深度逐渐降低,陇中土壤湿度对降水的敏感性大于陇东南。④不同级别的降水对土壤湿度有不同的影响。不同级别降水之间,土壤湿度的差异极其显著。降水级别从“较强-强”,土壤湿度增幅最大。建立了土壤湿度与不同级别降水的关系式。

Impact of Precipitation on Soil Moisture in Gansu Arid Agricultural Regions

This article analyzed relationship between soil moisture and precipitation in arid agricultural regions in Gansu province based on precipitation data from 1961—2007 of 35 weather stations and soil moisture data during April-October of 13 agricultural meteorological observation stations.Using the REOF method we divided the area into 4 sub-areas: east sub-area,mid-west sub-area,mid-east sub-area and south sub-area.Results show that:(1) In 0—100 cm soil layers,relation between 0—30 cm plow layer soil moisture and precipitation is best.(2) Yearly change tendencies of precipitation and soil moisture at plow layer in Gansu arid agricultural regions are consistent.Soil humidification time is basically consistent with the time of ten-day precipitation achieving 20 mm in each sub-area.(3) There is an extremely remarkable correlation between soil moisture at plow layer and precipitation.The sensitivity of soil moisture to precipitation decreases gradually along with the soil depth increase;the sensitivity is bigger in middle sub-area than in southeast sub-area.(4) Different grades of precipitation have different influence on the soil moisture.The soil moisture difference is extremely remarkable for different grades of precipitation.The soil moisture increase range is the biggest when precipitation grade change from slightly strong to strong.Lastly,soil moisture-precipitation regression equations are established.