干热河谷冲沟沟床土壤水分时空分异特征

为探究干热河谷冲沟沟床土壤水分时空分异特征，选取了元谋干热河谷1条典型冲沟，对其不同分段(沟头、上游、中游、下游)下10,20,30,40,60,100 cm土层的土壤水分开展定位监测。结果表明：(1)沟床不同分段各土层(除100 cm土层外)含水量整体变化趋势一致，均表现为明显的干湿季特征；湿季(5—10月)土壤水分相对较高(7.64%～28.91%),受降雨影响大；干季(11—次年4月)则长期处于较低水平(6.11%～11.97%)。(2)沟床土壤水分从沟头至下游沿程变化在干湿季有明显差异，湿季表现为先减小后增加，下游(17.36%)显著高于沟头(15.46%)和上游(12.19%);干季则是先减小后增加再减小，沟头(10.64%)显著高于上游(6.74%)和下游(9.10%)。不同土层深度上，浅层(10—20 cm)和深层(60—100 cm)土壤水分含量在干湿季均较高，水分最小值出现在30—60 cm土层，其中干季30 cm土层水分亏缺严重。(3)沟床土壤水分最高日期通常出现在7日内累积降雨达76.1 mm以上的年最大降雨月当月；最低日期通常出现在持续无降雨条件下，如干季末期，...

Spatial and Temporal Variability of Soil Moisture in Gully Bed of Dry-Hot Valley

A typical gully in the dry-hot valley of Yuanmou County was selected to study the spatiotemporal variation of soil moisture in the gully bed, and the soil moisture in soil layers of 10,20,30,40,60 and 100 cm from different plots(gully head, upstream, midstream and downstream)was monitored. The results showed that:(1)the water contents of all soil layers(except 100 cm soil layer)in different plots of the gully bed showed obvious characteristics of dry and wet seasons; the soil water contents during wet season(May to October)were high(7.64%～28.91%)and greatly influenced by rainfall, while those during dry season(November to April of the next year)were low(6.11%～11.97%);(2)the soil moisture from the gully head to the downstream of the gully bed decreased firstly and then increased in wet season, and the water content in the downstream(17.36%)was significantly higher than those in the gully head(15.46%)and the upstream(12.19%); in dry season, the soil moisture in the gully head(10.64%)was significantly higher than that in the upstream(6.74%)and downstream(9.10%); the water contents in the soil layers of 10—20 cm and 60—100 cm were higher both in dry and wet seasons, while those in the soil layers of 30—60 cm was low, and the most severe water deficit was observed in the 30 cm soil layer in dry season;(3)the max value of soil moisture in gully bed usually occurred in the month with the largest rainfall and the accumulated rainfall more than 76.1 mm within 7 days, and the min value usually occurred under continuous no rainfall conditions, such as from the end of dry season to the beginning of the rainy season with the occurrence of first effective rainfall(>2 mm). In conclusion, the soil water characteristics of dry and wet seasons, different positions of the stable gully beds and profile water distribution should be taken into account to select planting vegetation.