基于下游河流健康的黄土高原土壤容许流失量

 在总结分析前人有关黄河下游冲淤平衡时不同含沙量的临界流量和水体污染物质量浓度研究成果的基础上,利用花园口、高村水文站逐日水沙资料,推算不同水文年黄河下游水沙冲淤平衡时的临界输沙量为平水年6.54亿t、丰水年8.83亿t、枯水年3.95亿t,平均6.44亿t。以氨氮和全磷为指标,分析三门峡、花园口和高村断面因水土流失引起的非点源污染状况,参照地表水环境质量标准,得到黄河下游河道达到Ⅲ类和Ⅱ类水质标准的临界输沙量三门峡至高村河段平均为7.93亿和5.20亿t。同时,以黄河下游河道水沙平衡和满足某一水质标准为河流健康的约束条件,结合水利水土保持措施减沙量、头道拐水文站多年平均输沙量和黄土高原泥沙输移比的研究成果,推算黄河下游河道水沙平衡且分别达到Ⅲ类或Ⅱ类水质标准时,黄土高原土壤容许流失量相应为9.41亿和8.41亿t。研究结果可为黄土高原水土流失治理提供科学依据。

Soil loss tolerance in the Loess Plateau based on the healthy function of the lower reaches of the Yellow River

Based on previous researches on critical flow of different sediment concentration under equilibrium between scouring and deposition and pollutants concentration in the lower reaches of the Yellow River,using the daily flow and sediment yield of Huayuankou and Gaocun hydrologic station,we calculated the critical sediment discharge,which is 6.54×108 t in average year,8.83×108 t in high flow year and 3.95×108 t in dry year with an average of 6.44×108 t,when the lower reaches of Yellow River is in equilibrium between scouring and deposition.Taking ammonia nitrogen and total phosphorus as indicators,we analyzed the non-point source pollution caused by water and soil loss in Sanmenxia,Huayuankou and Gaocun section,and got the critical sediment discharge,which is 7.93×108 t and 5.20×108 t in Sanmenxia to Gaocun interval averagely,when the lower reaches of Yellow River up to the standard of Ⅲ and Ⅱ water quality based on environment quality standards of surface water.Considering equilibrium between scouring and deposition and water quality criterion as the constraint conditions of the healthy function of he lower reaches of the Yellow River,and combining the reduced sediment discharge by water conservancy and soil and water conservation,average sediment discharge of Toudaoguai hydrologic station,sediment discharge ratio of the Loess Plateau,we obtained soil loss tolerance of Loess Plateau,which is 9.41×108 t or 8.41×108 t when water quality up to Ⅲ or Ⅱ standard with equilibrium between scouring and deposition as well in the Lower reaches of the Yellow River.It provides scientific basis for the soil erosion control in the Loess Plateau.