陕北黄土丘陵区乡村聚落发展的土壤侵蚀效应

Soil Erosion Effect of Rural Settlements Development in Loess Hilly Area of North Shaanxi

通过定位观测和实地调查,对陕北黄土丘陵区已建乡村聚落的水力侵蚀、新建窑洞(房)过程中的弃土侵蚀及窑洞坍塌形成的侵蚀进行了研究,结果表明:①观测期间(2004.6～2004.10),乡村聚落的平均水力侵蚀强度为5 434.3 t/km2,已达到强度级侵蚀,其中户间道路为7 348.0 t/km2,户间空地为6 873.2 t/km2,院落为2 081.7 t/km2;②新建1孔(间)窑洞或平房,平均弃土34.9 m3,相当于动土量的23.6%;延安以北丘陵区近20年新建窑(房)平均每年弃土7 957.2万m3,弃土年流失量约为517.22万m3(775.83万t/a);③在调查的102孔(间)塌窑所形成的松散堆积体,平均每孔(间)窑(房)年流失泥沙46.3 m3,延安以北丘陵区因塌窑每年流失泥沙1 249.17万m3(1 873.76万t/a).以上说明乡村聚落发展带来了较严重的土壤侵蚀,应加强研究与防治.

On the basis of field-fixing-spot survey and field investigation, water erosion of rural settlements built, deserting soil erosion during constructing new caves （or houses） and the soil erosion caused by cave collapsing are studied in the loess hilly area of north Shaanxi. It concludes that： （a） From June of 2004 to October of 2004, the average water erosion intensity of rural settlements is annually 5 434.3 t/km^2. The average water erosion intensity per year of roads （between houses）, open space （between houses） and yards is 7 348.0 t/km^2, 6 873.2/km^2 and 2 081.7 t/km^2 individually; （b） The average deserting soil amount of a new-built cave or house is 34.9 m^3, occupying 23.6% of the digging soil. The average deserting soil amount per year of new caves （or houses） is 7. 957 2× 10^7 m^3 during recent 20 years in the much and coarse sediment area of Yulin and Yan＇an, with annual deserting soil loss 5. 172 2 × 10^6 m^3（7. 758 3 × 10^6 t）; （c） According to the accumulation volume formed by 102 caves （houses） investigated, the annual sediment loss per collapsing cave （or house） is 46.3 m^3. The annual sediment loss amount caused by collapsing caves in Yulin city is 12. 491 7 × 10^6 m^3（1. 873 76 × 10^7 t）. The above conclusions make out that the development of rural settlements brings out more serious soil erosion. It must be paid more attentions to study, prevention and cure.