红壤坡地土壤水分时间序列分析

基于时间序列法，分析了2002—2004年3—9月茶园和农作区两种土地利用方式下土壤水分与降雨的相关关系.结果表明，降雨为不相关序列，而不同深度(10、30、50、70和90 cm)土壤含水量有高度自相关性，为自相关序列，相关时间域为30～45 d.降雨和土地利用方式是影响土壤水分与降雨相关关系的主要因素.降雨对土壤水分的影响强度由表层到深层不断减弱，其在土壤表层(10和30 cm)的有效性时间为7～8 d；在深层有效时间长短不一，但雨后2～3 d，降雨对土壤水分(0～100 cm)的影响最显著.旱季土壤含水量与降雨的相关时间比雨季短1～3 d，若持续5 d降雨量小于5 mm，土壤表层水分含量就会明显降低，可能引发季节性干旱.与农作区相比，降雨对茶园表层水分的影响较弱，但对深层水分的影响较强且持续时间长.

Time series analysis of soil water on sloping land in red soil hilly region

Based on time series analysis, the correlation between soil water and precipitation on the sloping land in red soil hilly region under two land use modes was studied from March to September, 2002-2004. The results showed that precipitation was not an autocorrelation series, while soil water at the depths of 10, 30, 50, 70 and 90 cm was an autocorrelation series with 30-45 days of time correlation range. Precipitation and land use mode were the main factors affecting the correlation of soil water and precipitation. The effect of precipitation weakened gradually with increasing soil depth. This effect lasted 7-8 days in upper soil layers (0-10 and 0-30 cm) , but no marked regularity was observed in deeper soil layers. 2-3 days after raining, precipitation had the most prominent effect on soil water in 0-100 cm soil layer. The correlation time range was 1-3 days shorter in dry season than in wet season. When it didn' t rain more than 5 days, the water content in topsoil would decrease, and even, lead to seasonal drought. Compared with farmland, tea plantation had a weaker correlation between soil water and precipitation in surface soil, but a stronger and more persistent correlation in soil layers below 50 cm.