黄土高原典型半干旱区水热变化及其土壤水分响应

Climate Evolvement and Response of Soil Moisture in Typical Semi-arid Region on Loess Plateau

利用黄土高原典型半干旱代表区68a(1937-2004年)降水、气温资料和34a(1971-2004年)土壤湿度资料,研究黄土高原半干旱区水热变化及土壤水分响应。结果表明:黄土高原半干旱区在近70a中气温以下降为主,3-6月降水存在显著增多趋势,气温、降水倾向具有明显时段差异。干旱年份或少雨时段长周期振荡加强、短周期衰减;相对冷的时期气温振荡周期明显,反之不明显。干旱是该地区土壤的基本气候特征,生长期土壤水分波动式下降,蓄水期土壤水分波动式上升,总体上以下降为主,20世纪70年代中后期土壤水分较好,80年代土壤水分较差,90年代末到21世纪初转好。土壤水分对短期降水变化、降水气温气候变化及短周期振荡都存在明显响应。

Based on the rainfall and temperature data from 1937-2004 and soil moisture data from 1971-2004 in - cal semi-arid area on Loess Plateau, we studied the rainfall and temperature changes and the response of soil moisture by applying the wavelet analysis method. Results showed that the annual rainfall and the annual temperature had decreasing trend in the nearly 70 years, but; the rainfall from March to June had increasing trend. In details, the change trend of rainfall and temperature existed difference among time stages. Precipitation before 1958 mainly showed negative anomaly, 1959-1979 was rainy period, since 1979 rainfall gradually decreased and after 1998 it again had increasing trend. The temperature before 1977 was decreasing on the whole, and gradually increased after 1977. The change of rainfall existed a shorter period of 4-6 years and a longer period of 14-16 years; the change of temperature had no remarkable period in warmer years, but had a period of 5-9 years in colder years. Soil moisture easily responded to the short-term rainfall change, the short-period oscillation of rainfall and temperature. The principal character of soil water in this region was arid. On the whole, soil moisture had a decreasing trend from 1971-2004, with a fluctuating decreasing trend in growth season and a fluctuating increasing trend in saturation season; for details, soil moisture was better in middle and late 1970s, worse in 1980s, became good since end of 1990s.