Comparing the Export Coefficient Approach with the Soil and Water Assessment Tool to Predict Phosphorous Pollution: The Kan Watershed Case Study
Comparing the Export Coefficient Approach with the Soil and Water Assessment Tool to Predict Phosphorous Pollution: The Kan Watershed Case Study
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DOI：
10.1007/s11270-014-2122-7
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发表时间：
2014-09
期刊：
影响因子：
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通讯作者：
Madjid Delkash;F. Al-Faraj;M. Scholz
中科院分区：
文献类型：
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作者：
Madjid Delkash;F. Al-Faraj;M. Scholz
水质保护已成为水资源开发和管理中的一个重要问题。不加控制的营养输入可能会对一些水体的质量构成挑战。本研究以德黑兰(伊朗)西北部相对陡峭的坎流域为例进行案例研究，该流域目前正在建设一个人工湖，用于娱乐目的。评估了两种预测年总磷负荷的方法：土壤和水评估工具(SWAT)和输出系数法。在对SWAT中的总磷(TP)负荷进行建模之前，对河流流量和泥沙输送进行了模拟，以使模型更加准确。此外，还采用了一种从上游到下游的校准方法。结果表明，SWAT模拟的磷负荷具有合理的纳什-萨克利夫效率(ENS)值(校准时ENS值为75%，验证时ENS值为52%)。估算年总磷负荷的相对误差为7%。出口系数法是为每种土地利用分配出口系数的方法，是一种可用于估算TP负荷的替代方法。从文献中选取了四组输出系数来检验它们在TP负荷预测中的适用性。结果表明，TP负荷预测存在显著误差，这表明输出系数可能是特定于流域的。同样，出口系数被发现在四个潮湿的月份中变化不同，误差从9%到33%不等。本文论证了输出系数法可以用比改进的SWAT模型更少的数据来估算坎河流域的污染负荷。然而，它与更高级别的错误相关。
Water quality protection has become a key concern in water resources development and management. Uncontrolled nutrient input may challenge the quality of some water bodies. This study uses the relatively steep Kan watershed located in the north-west of Tehran (Iran) as an example case study, where an artificial lake is currently under construction for recreational purposes. Two approaches to predict the total annual phosphorous load were assessed: the soil and water assessment tool (SWAT) and the export coefficient approach. River discharge and sediment transport were simulated prior to modeling of the total phosphorous (TP) load in SWAT to make the model more accurate. In addition, an upstream to downstream calibration method was utilized. Findings reveal that the SWAT-simulated phosphorous load had sound Nash–Sutcliffe efficiency (ENS) values (ENSof 75 % for calibration andENSof 52 % for validation). The relative error in estimating annual TP load was 7 %. The export coefficient approach assigning coefficients of export for each land use is known as an alternative method that can be used for estimating the TP load. Four sets of export coefficients were selected from the literature to examine their suitability in TP load prediction. The results showed significant errors in TP load prediction, which indicates that export coefficients are likely to be watershed-specific. Likewise, the export coefficients were found to vary through four wet months with errors ranging from 9 % to 33 %. This paper demonstrates that the export coefficient method may estimate the pollution load in the Kan watershed with less data than the advance SWAT model. However, it is associated with a higher level of error.