Double Exposures: Future Water Security across Urban Southeast Asia

Abstract

Southeast Asia is one of the most dynamic regions in the world in terms of economic growth and urbanization. At the same time, the region is also prone to multiple hydro-meteorological disasters, which are projected to be intensified by climate change. This paper analyzes the combined effect of economic development and climate change on the future water security of middle-income Southeast Asian countries using the double exposure framework, focusing on the effects in urban areas. A review of the existing literature reveals unequal water security outcomes across the region as a result of combined climate, economic, and urbanization pressures. The water supply and sanitation infrastructure of upper-middle-income Southeast Asian countries are vulnerable to damage from intensified disasters, potentially decreasing both immediate and longer-term water quality. In lower-middle-income countries, the water quality will be the more important water security challenge in the short-term as opposed to water quantity, mainly due to the fast growth of industries. Lower-middle-income countries, though less vulnerable to disasters, will still have lower future water security compared to upper-middle-income countries, as they have less capacity to address water quality and quantity challenges brought about by both industrial growth and urbanization. Across the region, future water quantity and quality challenges may result in slower economic and urban growth if not planned adequately.

Opportunities and limits of wastewater-based epidemiology for tracking global health and attainment of UN sustainable development goals

“…Inadequate maintenance of existing systems in 2017 earned the USA a dismal rating of D + for its wastewater infrastructure ( ASCE, 2017 ). And yet, the condition of wastewater infrastructure in other parts of the world, especially in South Asia, Central Asia, and Africa, is even worse than that of the USA ( Karthe et al, 2017 , Lorenzo and Kinzig, 2019 , Wang et al, 2014 ). Rapid urbanization in these locales demands investments into the construction of more wastewater infrastructure; yet, a lack of economic stature, political stability and forward-looking planning is placing millions of people in jeopardy.…”

Occurrence of Emerging Contaminants in Southeast Asian Environments: Present Status, Challenges, and Future Prospects

“…Southeast Asia is a region extremely vulnerable to the threat of emerging contaminants due to (i) high population density; (ii) agriculture and livestock expansion; (iii) climate change . The total population in Southeast has grown by 37.9% from 1995 to 2019, , and heavily populated countries including Indonesia, Philippines, Malaysia, and Thailand have an urban population making up nearly 50% of their total population.…”

“…The installation of new and advanced sewage treatment infrastructures to replace cesspit and septic tank systems to mitigate EC contamination will be a tremendous task that can only be fulfilled in the long run. Until then, existing inadequate sewage treatment plants will continue to act as sources of emerging contaminants into the aquatic environment in most parts of Southeast Asia. , In most parts of Southeast Asia, except for Singapore and Malaysia, less than 15% of the population have access to a proper sewerage system . On-site sanitation systems are the most common domestic waste disposal facility used in peri-urban and rural areas of Southeast Asia and are also common sources of groundwater or surface water pollution .…”

“…Moreover, as a region facing increasing drought risk, low streamflow in surface water or baseflows in groundwater during the dry season will result in the increase in concentrations of emerging contaminants in these aquatic environments. ,, On the other hand, more intense storms and floods associated with climate change in this region increase the overall risk of wear and tear of the sewage infrastructure, resulting in high risks of EC carrying-sewage contamination into the environment …”

“…Moreover, being situated in a tropical monsoonal climate, Southeast Asia countries are exposed to seasonal wet and dry seasons, which in turn, can affect the concentration of ECs in water resources . Low flows during the dry season reduce the dilution of contaminants discharged into freshwater systems, thereby resulting in contaminants occurring at higher concentrations, especially in urbanized or highly populated areas . During the wet season, concentrations of ECs tend to be lower, diluted by runoff and precipitation …”