Water Systems and Global Change Group, Wageningen University & Research, Droevendaalsesteeg 4, 6708 PB Wageningen, the Netherlands.
International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1 - A-2361, Laxenburg, Austria.
Sci Total Environ. 2019 Dec 1;694:133629. doi: 10.1016/j.scitotenv.2019.133629. Epub 2019 Jul 26.
The Indus River Basin faces severe water quality degradation because of nutrient enrichment from human activities. Excessive nutrients in tributaries are transported to the river mouth, causing coastal eutrophication. This situation may worsen in the future because of population growth, economic development, and climate change. This study aims at a better understanding of the magnitude and sources of current (2010) and future (2050) river export of total dissolved nitrogen (TDN) by the Indus River at the sub-basin scale. To do this, we implemented the MARINA 1.0 model (Model to Assess River Inputs of Nutrients to seAs). The model inputs for human activities (e.g., agriculture, land use) were mainly from the GLOBIOM (Global Biosphere Management Model) and EPIC (Environmental Policy Integrated Model) models. Model inputs for hydrology were from the Community WATer Model (CWATM). For 2050, three scenarios combining Shared Socio-economic Pathways (SSPs 1, 2 and 3) and Representative Concentration Pathways (RCPs 2.6 and 6.0) were selected. A novelty of this study is the sub-basin analysis of future N export by the Indus River for SSPs and RCPs. Result shows that river export of TDN by the Indus River will increase by a factor of 1.6-2 between 2010 and 2050 under the three scenarios. >90% of the dissolved N exported by the Indus River is from midstream sub-basins. Human waste is expected to be the major source, and contributes by 66-70% to river export of TDN in 2050 depending on the scenarios. Another important source is agriculture, which contributes by 21-29% to dissolved inorganic N export in 2050. Thus a combined reduction in both diffuse and point sources in the midstream sub-basins can be effective to reduce coastal water pollution by nutrients at the river mouth of Indus.
由于人类活动导致营养物质富集，印度河流域面临严重的水质恶化问题。支流中过多的营养物质被输送到河口，导致沿海富营养化。由于人口增长、经济发展和气候变化，这种情况未来可能会恶化。本研究旨在更好地了解印度河流域当前（2010 年）和未来（2050 年）在次流域尺度上总溶解氮（TDN）的河流输出量的规模和来源。为此，我们实施了 MARINA 1.0 模型（评估河流向海洋输入营养物质的模型）。人类活动（如农业、土地利用）的模型输入主要来自 GLOBIOM（全球生物圈管理模型）和 EPIC（综合环境政策模型）模型。水文模型输入来自社区水模型（CWATM）。对于 2050 年，选择了三种结合共享社会经济途径（SSP1、2 和 3）和代表性浓度途径（RCP2.6 和 6.0）的情景。本研究的一个新颖之处在于对印度河未来 N 出口的次流域分析。结果表明，在三种情景下，2010 年至 2050 年期间，印度河的 TDN 河流出口将增加 1.6-2 倍。印度河流出的溶解氮中，>90%来自中游次流域。人类废物预计将成为主要来源，根据情景的不同，2050 年人类废物对 TDN 河流出口的贡献将达到 66-70%。另一个重要的来源是农业，它在 2050 年对溶解无机氮的出口贡献了 21-29%。因此，在中游次流域减少点源和非点源污染可以有效地减少印度河口沿海地区的营养物质水污染。
