基于非点源溶解态氮负荷估算的率水流域土地利用结构优化研究

利用区域营养盐管理模型(ReNuMa)对率水流域2000~2010年的溶解态氮(DN)负荷进行了定量估算和来源解析.在率定期和验证期,径流和DN负荷模拟的Ens和R2都大于0.9,模型具备可靠的模拟能力.结果表明,率水流域的年均非点源DN负荷为1.11×103t·a-1,负荷强度为(0.75±0.22)t·km-2.在所有土地利用类型中,水田的DN负荷强度最大28.60kg·(hm2·a)-1],林地的DN负荷强度最小2.71 kg·(hm2·a)-1].农业生产用地(水田、谷物、经济作物、果园和茶园)对DN负荷的贡献最大,表明人类影响下的农业生产活动是流域非点源污染的最主要来源.基于污染负荷适量削减和农业经济产值最大化原则,开展了流域2015年土地利用结构优化分析,规划结果表明在土地利用结构最优情况下,经济收益的增长依然伴随着负荷的增加,但经济产值的增幅大于DN负荷的增幅.

Research on Land Use Structure Optimization Based on Nonpoint Source Dissolved Nitrogen Load Estimation in Shuaishui Watershed

Regional Nutrient Management (ReNuMa) was applied to estimate dissolved nitrogen (DN) load and perform source apportionment in Shuaishui watershed during 2000-2010.Satisfactory performance of ReNuMa was revealed by the E_ns and R² of greater than 0.9 in calibrating and validating streamflow and DN. The average nonpoint DN load in this watershed was 1.11×10³ t·a^-1, with the load intensity of (0.75±0.22) t·km^-2. Among all the land uses, paddy field had the largest DN load intensity 28.60 kg·(hm²·a)^-1], while forest had the least 2.71 kg·(hm²·a)^-1]. Agricultural land (including paddy, grain, cash crop, tea plant and orchard) contributed most to DN load in Shuaishui watershed, indicating that the human dominated agricultural activities was the major contributor of nonpoint source pollution. Land use structure optimization for Shuaishui watershed in 2015 was conducted under the rule of reducing pollutants loads and maximizing the agricultural output value. The results demonstrated that agricultural monetary growth was accompanied with the increasing DN load at the optimal level, although output increment was higher than that of DN load.