三峡库区不同退耕还林模式林地水文效应

Woodland Hydrological Effects of Converting Cropland to Forest in the Three Gorges Reservoir Region

在三峡库区兰陵溪小流域内选定3种典型退耕还林模式,基于2007—2009年连续3a的观测,对退耕还林林地水文效应进行了定量研究。结果表明:(1)与坡耕地比较,退耕还林地土壤总孔隙度增加4.2%～11.5%,非毛管孔隙度增加了69.1%～162.6%,平均可增加饱和蓄水量42.5%,非毛管蓄水量221.4%;(2)各退耕还林模式A层土壤的初渗速率和稳渗速率分别在2.73～4.74mm/min和1.30～2.96mm/min,与对照相比A层土壤渗透性能差异不大,B层土壤初渗及稳渗速率分别较对照提高0.85～5.21倍和3.33～6.83倍,在0.14～0.87mm/min和0.06～0.47mm/min间变动;(3)各退耕还林模式年均径流深为13.21～22.38mm,较农耕地减少74.7%～57.3%,各退耕模式土壤侵蚀模数在137.1～331.1t/(km2.a),较对照减少92.4%～81.6%。

Based on 3 year（2007—2009） continuous observations,characteristics of woodland hydrological effects from the three typical models of converting cropland to forest were studied in Lanningxi small watershed of the Three Gorges Reservoir region.Results are as follows：（1） Compared with sloping farmland,the total soil porosity and non-capillary porosity increased from 4.2% to 11.5% and 69.1% to 162.6%,respectively.The maximum soil water capacity and non-capillary water capacity increased by 42.5% and 221.4%,respectively,after converting cropland to forest.（2） Initial infiltration rate and stable infiltration rate in A layer for each of the three models were between 2.73 and 4.74 mm/min and 1.30 and 2.96 mm/min,respectively,which had no great differences from those on sloping farmland;and in B layer,between 0.14~0.87 mm/min and 0.06~0.47 mm/min,respectively,which were 0.85~5.21 and 3.33~6.83 times of those on sloping farmland.（3） The surface runoff depths for the three models were between 13.21 and 22.38 mm,which were reduced by 74.7%~57.3% as compared with those on cropland.The average annual soil erosion modulus for the three models were between 137.1 and 331.1 t/km2,which were reduced by 92.4%~81.6% in contrast to CK.