Water quality modelling of the Mekong River basin: Climate change and socioeconomics drive flow and nutrient flux changes to the Mekong Delta.
Water quality modelling of the Mekong River basin: Climate change and socioeconomics drive flow and nutrient flux changes to the Mekong Delta.
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DOI：
10.1016/j.scitotenv.2019.03.315
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发表时间：
2019-04
期刊：
影响因子：
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通讯作者：
P. Whitehead;P. Whitehead;Li Jin;G. Bussi;H. Voepel;S. Darby;G. Vasilopoulos;R. Manley;H. Rodda;C. Hutton;C. Hackney;V. Tri;N. Hung
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文献类型：
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作者：
P. Whitehead;P. Whitehead;Li Jin;G. Bussi;H. Voepel;S. Darby;G. Vasilopoulos;R. Manley;H. Rodda;C. Hutton;C. Hackney;V. Tri;N. Hung
湄公河三角洲被认为是世界上最脆弱的巨型三角洲之一，受到一系列环境压力的影响，包括海平面上升，人口增加，以及来自高地流域的水流和营养物质的变化。随着气候和社会经济的变化，有必要评估湄公河流域在向三角洲系统输送水和养分方面将受到何种影响。在这里，我们应用集成流域模型（印加），整个湄公河流域的流量和水质，包括硝酸盐，氨，总磷和可溶性活性磷模拟。气候变化对所有这些变量的影响已经在从喜马拉雅山到越南三角洲的24个河流流域进行了评估。我们使用英国气象局PRECIS区域耦合气候模型，以降尺度降水和温度的湄公河流域。这是使用全球环流模式GFDL-CM提供的边界条件下的两个碳控制策略，即代表性浓度途径（RCP）4.5和RCP 8.5情景。RCP 4.5情景代表了满足《巴黎雅阁》所需的碳战略，该协定旨在将全球峰值气温上升限制在2 °C以下，同时寻求将气温上升限制在1.5 °C以内的方案。RCP 8.5情景与更大的3-4 °C上升有关。此外，我们还构建了一系列社会经济情景，以调查人口变化、大气污染、经济增长和土地利用变化到2050年代的潜在影响。印加的模拟结果表明，平均流量增加了24%，季风期间的洪水流量增加了27%，但干旱期增加到2050年。还模拟了季风时间的转变，平均季风流的爆发提前了4周。氮和磷浓度的下降主要是由于水流稀释，但这些营养盐的通量也增加了5%，这反映了流量的变化，土地利用的变化和人口的变化。
The Mekong delta is recognised as one of the world's most vulnerable mega-deltas, being subject to a range of environmental pressures including sea level rise, increasing population, and changes in flows and nutrients from its upland catchment. With changing climate and socioeconomics there is a need to assess how the Mekong catchment will be affected in terms of the delivery of water and nutrients into the delta system. Here we apply the Integrated Catchment model (INCA) to the whole Mekong River Basin to simulate flow and water quality, including nitrate, ammonia, total phosphorus and soluble reactive phosphorus. The impacts of climate change on all these variables have been assessed across 24 river reaches ranging from the Himalayas down to the delta in Vietnam. We used the UK Met Office PRECIS regionally coupled climate model to downscale precipitation and temperature to the Mekong catchment. This was accomplished using the Global Circulation Model GFDL-CM to provide the boundary conditions under two carbon control strategies, namely representative concentration pathways (RCP) 4.5 and a RCP 8.5 scenario. The RCP 4.5 scenario represents the carbon strategy required to meet the Paris Accord, which aims to limit peak global temperatures to below a 2 °C rise whilst seeking to pursue options that limit temperature rise to 1.5 °C. The RCP 8.5 scenario is associated with a larger 3–4 °C rise. In addition, we also constructed a range of socio-economic scenarios to investigate the potential impacts of changing population, atmospheric pollution, economic growth and land use change up to the 2050s. Results of INCA simulations indicate increases in mean flows of up to 24%, with flood flows in the monsoon period increasing by up to 27%, but with increasing periods of drought up to 2050. A shift in the timing of the monsoon is also simulated, with a 4 week advance in the onset of monsoon flows on average. Decreases in nitrogen and phosphorus concentrations occur primarily due to flow dilution, but fluxes of these nutrients also increase by 5%, which reflects the changing flow, land use change and population changes.