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| 流域尺度磷素两级输出系数模型构建及应用 |
| Construction and application of a two-stage phosphorus export coefficient model at the watershed scale |
| 投稿时间：2025-02-05 |
| DOI：10.13254/j.jare.2025.0068 |
| 中文关键词: 磷输出负荷 两级输出系数模型 丰乐河流域 农业面源 关键源区 |
| 英文关键词: phosphorus export load two-stage export coefficient model Fengle River watershed agricultural non-point source critical source area |
| 基金项目:国家重点研发计划项目（2023YFD1702101） |
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| 中文摘要: |
| 为了快速准确评估流域尺度不同来源磷素的输出负荷，本研究将磷输出过程概化为子流域输出和河道迁移两个过程，提出磷两级输出系数，即子流域磷输出系数和河道磷输出系数，并建立相关计算式；在此基础上，构建磷两级输出系数与其影响因子的关系模型。将该模型应用于巢湖丰乐河流域，借助经过率定和验证的SWAT模型获得各子流域出口及流域总出口磷输出负荷，计算不同子流域、不同年份磷两级输出系数，构建了子流域磷输出系数与子流域降雨因子、坡度因子和河网密度因子的回归模型，以及河道磷输出系数与河道降雨因子、坡度因子和距离因子的回归模型，决定系数分别为0.85和0.97，拟合结果较好。利用丰乐河流域磷两级输出系数模型模拟该流域2012—2021年的磷输出负荷，结果总体较好，年均输出负荷与实测值相对误差为5.50%；基于丰乐河流域农业污染源输入的磷负荷，利用该模型模拟的农业面源磷年均输出负荷范围在0.01~0.41 kg·hm-2·a-1之间，平均值为0.12 kg·hm-2·a-1，农业面源磷关键源区主要为污染源输入磷负荷高、降雨量和坡度大、河网密度低和河道距离近的子流域。研究表明，磷两级输出系数模型能准确、动态、快速地估算不同年份、不同来源各子流域磷输出负荷，并且可识别关键源区。 |
| 英文摘要: |
| To accurately and quickly assess the total export load of phosphorus from different sources at the watershed scale, the phosphorus export processes were generalized into sub-watershed export and channel routing, and the corresponding two-stage phosphorus export coefficients, i.e. the sub-watershed phosphorus export coefficient and the river channel phosphorus export coefficient, were proposed and the related calculation formulas were established. The two-stage coefficient model was then developed that included two equations describing the relationships between the coefficients and their influencing factors. The model was applied to the Fengle River watershed of Chaohu basin, where the export coefficients of phosphorus from sub-watersheds and the channel routing coefficients of river reaches of different years were calculated based on the export load results at the outlets of the sub-watersheds and the outlet of the whole watershed obtained from the calibrated and validated SWAT（Soil and Water Assessment Tool）model. The regression equation between the subwatershed phosphorus export coefficient and sub-watershed rainfall factor, slope factor, and river network density factor, and that between the channel routing coefficient and channel rainfall factor, slope factor, and distance factor, were established, with the determination coefficients being 0.85 and 0.97, respectively, indicating high reliability of the fitting results. The two-stage phosphorus export coefficient model was applied to simulate the phosphorus export load from Fengle River watershed from 2012 to 2021, showing generally good agreement, with the relative error between the calculated annual export load and the measured value being 5.50%. Based on the phosphorus input load of agricultural pollution sources in the Fengle River watershed, the simulated yearly average export phosphorus load from agricultural activities ranged from 0.01 to 0.41 kg · hm-2 · a-1, with an average value of 0.12 kg · hm-2 · a-1. The critical source areas of agricultural non-point source phosphorus were identified mainly as sub-watersheds with high phosphorus load inputs from pollution sources, large rainfall and slope, and small river network density and river distance. The two-stage phosphorus export coefficient model is proved to be a practical tool, that could accurately, dynamically, and efficiently estimate phosphorus export loads from various sources across sub-watersheds and different years at the watershed scale, as well as identify critical source areas. |
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