涟江流域不同类型河岸带模拟径流过程及氮流失研究 Study on Simulation of Runoff and Nitrogen Loss in Different Types of Riparian Zone in Lian River Basin

本研究以涟江流域作为研究对象，采用路线调查法对流域河岸带类型进行调查，根据土地利用方式、植被类型、地形地貌、土壤质地、人类活动强度、植被覆盖度等指标对涟江流域河岸带分类，选取不同类型河岸带运用径流槽模拟地表径流冲刷，测定土壤水分入渗和地表径流中氮流失量，以期能为流域面源污染防治以及良好河岸带结构的构建提供参考。研究表明：草地 + 壤土 + 山地、V型河谷 + 重度干扰类型河岸带地表径流产生量最大，单次冲刷最大地表径流量为757 mL；农业用地 + 水稻田撂荒地 +丘陵、U型沟谷 + 壤土 + 重度人类干扰类型与农业用地 + 坡耕地裸地 + 丘陵、U型沟谷 + 壤土 + 重度人类干扰类型产生量最低，6次冲刷均未产生地表径流。水分入渗量则相反，这三种类型单次冲刷入渗量分别为43 mL、800 mL、800 mL。不同类型河岸带模拟冲刷径流中总氮、铵态氮、硝态氮流失量均随冲刷次数增多而降低，其中硝态氮流失量大于铵态氮流失量。总氮、铵态氮、硝态氮流失量最大为建设用地 + 裸地 + 壤土 + 山地、V型河谷+重度干扰类型河岸带，流失量分别为4.60 mg/L、1.74 mg/L、2.11 mg/L；流失量最小为草地 + 壤土 + 山地、V型河谷 + 重度干扰类型河岸带，流失量分别为1.56 mg/L、0.45 mg/L、0.47 mg/L。本研究从局域尺度揭示了不同河岸带氮流失特征。 A riparian zone is an ecotone between fresh-water ecosystems and terrestrial ecosystems. Understanding of the ecological processes occurring in the riparian zone will provide knowledge for a control of non-point source pollution in a watershed and restoration of riparian zones. Riparian zones along Lianjiang River in central Guizhou province of China were investigated through a route survey method to define the types of the riparian zones in Karst Rivers. According to the utilization of soil, vegetation types, topography, soil texture, the intensity of human activities and vegetation coverage, the types of the riparian zone along Lianjiang River were classified into eight types. Furthermore, Surface runoff, soil water infiltration and loss of nitrogen with the surface runoff were determined at the different sites representing these eight types of the riparian zones using a runoff trough under a condition of the simulation of the surface runoff. The results indicated that the surface runoff from the riparian type “Grass + loam + mountain and V-shaped valley + severe disturbance” is largest in a single or total event of the surface runoff. The surface runoff from both the riparian types “Agricultural land + rice paddies abandoned land + hills, U-shaped valleys + loam + intense human disturbance” and “Agricultural land + slope to bare land + hills, U-shaped valleys + loam + intense disturbance” is lowest, in which six times scouring soils could not generate the surface runoff. However, the water infiltration amount had an opposite result with three infiltration events, 43mL, 800mL and 800mL. The losses of total nitrogen, ammonium nitrogen, nitrate nitrogen from different river riparian zones increased along with a frequency of scouring, in which the losses of the nitrate nitrogen are higher than that of the ammonium nitrogen. The losses of the total nitrogen, ammonium nitrogen and nitrate nitrogen were largest in the riparian type “Construction land + bare land + loam + mountain and V-shaped valley + intense disturbance”, which were respectively 4.60mg/L, 1.74 mg/L and 2.11 mg/L. The losses of the total nitrogen, ammonium nitrogen and nitrate nitrogen were lowest in the riparian type “Grass + loam + mountain, V-shaped valley + intense disturbance”, which were respectively 1.56 mg/L, 0.45 mg/L and 0.47 mg/L. This study revealed the characteristics of nitrogen leaching loss from the different riparian zones.