基于CNMM-DNDC模型的流域氮负荷对土地利用与施肥管理的响应研究OA

To quantitatively analyze the individual and synergistic effects of land use changes and fertilization management changes on watershed nitrogen load,this study focused on the Fengyu River basin.Based on the CNMM-DNDC model,five scenarios were designed:the 2010 baseline scenario(SO)and four scenarios for 2019,including the actual scenario with simultaneous changes in land use and fertilization management(S1),the fertilization management scenario(S2),the land use change scenario(S3),and the 2019 baseline continuation scenario(S4).These scenarios quantitatively expressed the nitrogen load reduction potential under different pollution control measures.The results showed that:from 2010 to 2019,land use changes in the Fengyu River basin accounted for 1.5％of the total area,primarily involving the conversion of farmland to wetlands,with limited changes in other land use types.The CNMM-DNDC model performed well in simulating runoff and total nitrogen concentrations in the Fengyu River basin,with R2 values above 0.8 and NSE values above 0.65 during both the calibration and validation periods,indicating that the model is suitable for scenario analysis of nitrogen load in plateau agricultural watersheds.The load reduction rates under different scenarios are as follows:S1(11.2％)＞S2(10.5％)＞S3(1.6％).Si's nitrogen load reduction did not show a significant synergistic effect load rate.The interception effect of ecological engineering is restricted by wetland spatial layout and hydrological conditions,limiting the deposition and transformation of nitrogen in the water,so land use changes contribute little to nitrogen load reduction.Therefore,in agricultural watersheds,nitrogen pollution control should focus on optimizing fertilization,while also combining land use structure adjustment and ecological engineering to establish an integrated management model with"source reduction-interception"synergy.