Natural Resources and Ecosystem Services, Institute for Global Environmental Strategies, Hayama, Kanagawa 240-0115, Japan.
Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810, Japan.
Int J Environ Res Public Health. 2019 Nov 20;16(23):4597. doi: 10.3390/ijerph16234597.
Just a few decades ago, Adyar River in India's city of Chennai was an important source of water for various uses. Due to local and global changes (e.g., population growth and climate change), its ecosystem and overall water quality, including its aesthetic value, has deteriorated, and the water has become unsuitable for commercial uses. Adverse impacts of excessive population and changing climate are expected to continue in the future. Thus, this study focused on predicting the future water quality of the Adyar river under "business as usual" (BAU) and "suitable with measures" scenarios. The water evaluation and planning (WEAP) simulation tool was used for this study. Water quality simulation along a 19 km stretch of the Adyar River, from downstream of the Chembarambakkam to Adyar (Bay of Bengal) was carried out. In this analysis, clear indication of further deterioration of Adyar water quality by 2030 under the BAU scenario was evidenced. This would be rendering the river unsuitable for many aquatic species. Due to both climate change (i.e., increased temperature and precipitation) and population growth, the WEAP model results indicated that by 2030, biochemical oxygen demand (BOD) and concentrations will increase by 26.7% and 8.3%, respectively. On the other hand, under the scenario with measures being taken, which assumes that "all wastewater generated locally will be collected and treated in WWTP with a capacity of 886 million liter per day (MLD)," the river water quality is expected to significantly improve by 2030. Specifically, the model results showed largely reduced concentrations of BOD and , respectively, to the tune of 74.2% and 98.4% compared to the BAU scenario. However, even under the scenario with measures being taken, water quality remains a concern, especially in the downstream area, when compared with class B (fishable surface water quality desirable by the national government). These results indicate that the current management policies and near future water resources management plan (i.e., the scenario including mitigating measures) are not adequate to check pollution levels to within the desirable limits. Thus, there is a need for transdisciplinary research into how the water quality can be further improved (e.g., through ecosystem restoration or river rehabilitation).
就在几十年前，印度钦奈市的阿迪尔河曾是各种用途的重要水源。由于当地和全球变化（例如人口增长和气候变化），其生态系统和整体水质（包括其美学价值）已经恶化，水已不适合商业用途。预计未来人口过多和气候变化的不利影响仍将持续。因此，本研究专注于预测阿迪尔河在“照常营业”（BAU）和“采取措施”情景下的未来水质。本研究使用了水评估和规划（WEAP）模拟工具。对阿迪尔河从 Chembarambakkam 下游到 Adyar（孟加拉湾）的 19 公里河段的水质进行了模拟。在这项分析中，BAU 情景下到 2030 年阿迪尔河水质进一步恶化的明显迹象得到了证实。这将使该河流不适合许多水生物种。由于气候变化（即温度和降水增加）和人口增长，WEAP 模型结果表明，到 2030 年，生化需氧量（BOD）和 浓度将分别增加 26.7%和 8.3%。另一方面，在采取措施的情景下，假设“当地产生的所有废水都将在每天 8.86 亿公升容量的污水处理厂中收集和处理”，到 2030 年，河水水质预计将得到显著改善。具体而言，与 BAU 情景相比，模型结果显示 BOD 和 浓度分别大幅降低了 74.2%和 98.4%。然而，即使在采取措施的情景下，与国家政府期望的 B 类（可钓鱼的地表水水质）相比，水质仍然令人担忧，尤其是在下游地区。这些结果表明，当前的管理政策和近期的水资源管理计划（即包括缓解措施的情景）不足以将污染水平控制在理想范围内。因此，需要开展跨学科研究，探讨如何进一步改善水质（例如，通过生态系统恢复或河流修复）。
