陕北多沙粗沙区乡村聚落土壤侵蚀及防治对策

通过定位观测和实地调查,对陕北多沙粗沙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。(1)观测期间(200406—200410),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 a新建窑(房)平均每年弃土7.96×107m3,弃土年流失量约为5.17×106m3(7.76×106t/a);(3)在调查的102孔(间)塌窑所形成的松散堆积体中,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1.25×107m3(1.87×107t/a)。研究表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。

Soil Erosion and Its Prevention and Control Countermeasures of Rural Settlements in Abundant and Coarse Sediment Area of North Shaanxi

On the basis of field fixed-spot survey and investigation,soil erosion by water in rural settlements,soil erosion by earth discarding during new cave(or house) construction and soil erosion caused by cave collapse were studied in the loess hill area of North Shaanxi Province.From June of 2004 to October of 2004,the annual average soil erosion by water in rural settlements was 5 434.3 t/km².The annual average soil erosion by water on roads(between houses),open spaces(between houses) and yards was 7 348.0,6 873.2 and 2 081.7 t/km²,respectively.The average amount of discarded earth for a new-built cave or house was 34.9 m³,being 23.6% of the dug earth.The annual amount of discarded earth for all new caves(or houses) averaged over recent 20 years in the abundant and coarse sediment area of Yulin and Yan'an was as much as 7.96×10-7 m³,with annual soil loss by earth discarding up to 5.17×10⁶ m³(7.76×10⁶ t).According to the accumulated volume formed by 102 caves(houses) investigated,the annual earth loss per cave(or house) collapse was 46.3 m³.The annual amount of earth loss caused by cave collapse in Yulin was as much as 1.25×10-7 m³ (1.87×10-7 t).The above data show that the development of rural settlements brings out the more serious soil erosion.More attentions must be paid to the study,prevention and control of soil erosion in the region.