Adapting to urban flooding: a case of two cities in South Asia

Abstract

Cities in South Asia are experiencing storm water drainage problems due to a combination of urban sprawl, structural, hydrological, socioeconomic and climatic factors. The frequency of short duration, high-intensity rainfall is expected to increase in the future due to climate change. Given the limited capacity of drainage systems in South Asian cities, urban flooding and waterlogging is expected to intensify. The problem gets worse when low-lying areas are filled up for infrastructure development due to unplanned urban growth, reducing permeable areas. Additionally, solid waste, when dumped in canals and open spaces, blocks urban drainage systems and worsens urban flooding and waterlogging. Using hydraulic models for two South Asian cities, Sylhet (in Bangladesh) and Bharatpur (in Nepal), we find that 22.3% of the land area in Sylhet and 12.7% in Bharatpur is under flooding risk, under the current scenario. The flood risk area can be reduced to 3.6% in Sylhet and 5.5% in Bharatpur with structural interventions in the drainage system. However, the area under flood risk could increase to 18.5% in Sylhet and 7.6% in Bharatpur in five years if the cities' solid waste is not managed properly, suggesting that the structural solution alone, without proper solid waste management, is almost ineffective in reducing the long-term flooding risk in these cities.

What makes a ban on plastic bags effective? The case of Nepal

“…They are however a major source of non-degradable solid waste, estimated at 12 per cent in Nepal in 2012 (Manandhar, 2012; Asian Development Bank, 2013). Without effective management, they could become a major source of soil and water pollution (Baker, 2010) while also marring the beauty of the landscape and clogging the drainage systems, contributing thereby to floods (Spivy, 2003; Pervin et al ., 2019; Rai et al ., 2019). When burnt, these bags emit dangerous air pollutants and when dumped in landfill sites, their long decomposition process comprising toxic chemicals leaches into the ground, polluting ground water reservoirs.…”

Toward a research agenda on climate‐related migration

“…Growing cities located in regions experiencing more intense rainfall encounter interrelated infrastructure development and operational challenges, such as the need to clear uncollected municipal solid waste from newly built storm drains (Pervin et al., 2019).…”

Sustainable financing for municipal solid waste management in Nepal

“…Dumping of plastic waste in rivers and canals, in addition to drainage systems, results in flooding and water logging in low-lying areas. In such situations, structural interventions can provide only a short-term solution in the absence of MSW management [6]. Similarly, imposing a ban on plastic use without strict enforcement may not work properly [18].…”

“…The increase in urban population, coupled with economic growth and improved living standards, has resulted in the generation of enormous amounts of waste already in cities in developing countries [ 2 ]. But municipal solid waste (MSW), if not managed properly, produces negative externalities and contributes to flooding and waterlogging during extreme climatic events such as excessive rainfall [ 3 – 6 ].…”