On July 12, the Balkhu and Kuleshwor areas witnessed the highest flood level ever recorded. Urban floods in the Kathmandu Valley were once anomalies. But now almost every resident of Kathmandu has experienced the effects of these disasters that occur every monsoon. What's more, these floods are often triggered by just a single night of routine rainfall. There are numerous examples from recent years, like the inundation of the Radhe Radhe area of Bhaktapur in 2018 where it took four days to pump the floodwater from the Bhatbhateni basement.

Urban flooding is an under-recognised problem, especially in Nepal. The floods are often too localised for a large-scale governmental or NGO response, but the effects in an economic and political centre like Kathmandu can have widespread consequences. However, residents of Kathmandu Valley have long been aware of the threats posed by flooding and settlement in flood-prone areas. The knowledge systems behind the culturally and religiously significant ponds that dot the city centre, like the importance of groundwater recharge, monsoon rainwater storage, and drainage infrastructure, can and should be adapted to a modern context to help make Kathmandu a more livable city.

Causes of urban floods

The reasons for the increased frequency of these floods are complex. As residents of Kathmandu are increasingly moving out of the over-crowded city centre, their search for new land has resulted in haphazard peri-urban development. In many places, this has occurred in the rivers’ right-of-way and floodplains.

Additionally, 'the rains are like someone is pouring from a bucket, really fast and all at once, and then the water just runs away to the river,' KP, a trekking guide based in Patan, said describing the monsoon. But he said this type of precipitation pattern is a recent phenomenon, a change that he and many Kathmandu residents have been able to observe directly. Although rainfall data collected by the Department of Hydrology and Meteorology shows that the quantity of average daily rainfall has not changed over the past thirty years, the period of rain within a single day has shortened. Due to the vast amount of concrete that covers the city and the lack of stormwater management systems, the infrastructure cannot accommodate the frequent short bursts of high-intensity rainfall, which results in much of the urban flooding in Kathmandu.

Problems with current interventions

Urban flooding is a legislative problem as well as a technical and environmental one. Shiv Kumar Basnet, the Executive Director of the Water Resource, Research, and Development Center at the Ministry of Energy, Water Resources and Irrigation, says that encroachment on the rivers and settlement in the rivers’ right-of-way has made it so that even normal flooding events, now, cause property damage and seem even more devastating. ‘Even the Land Revenue Office is on encroached land!’ he exclaimed. ‘The department that is supposed to regulate where people settle is itself on the land it should be preventing people from building on.’

Although policies exist to regulate the development of the riverscapes, interference with the natural flow of the rivers continues, in part, due to the complicated and fragmented bureaucratic structure of the many government bodies responsible for different aspects of urban planning like road development and water system management. Theoretically, Kathmandu could get rid of all development in the hazard areas, Basnet says, but wiping out this infrastructure is not feasible.

Currently, the construction of walled river corridors, managed by the Kathmandu Valley Development Authority (KVDA), is used as the primary intervention to address flooding in the urban core. According to Bhaikaji Tiwari, the development commissioner of KVDA, the river widths have been set as per the 20-year flood provisions, and the additional road area before the private land that begins on either side of the rivers is intended to prevent property damage for up to a 50-year flood. However, a study by the Department of Water Induced Disaster Management (DWIDM) has shown that none of the corridors in the Kathmandu Valley meet requirements to prevent the increased frequency of major floods. Additionally, because the legislature does not address the effects of climate change on rainfall patterns, the flood frequency is not likely to decrease even with corridor construction.

Sustainable urban development

'Constraining the rivers is like putting a bird in a cage,' Basnet says. He thinks that the rivers, which he describes as the 'life of the city,' ought to flow freely. While many agree with him, these corridor projects continue, and so do the floods. Therefore, the processes of sustainable urban development must be rethought. This is especially important now. Experts agree that changes in the global climate will cause more extreme weather events and Nepal, ranked the fourth most affected country by the Climate Risk Index of 2017, is especially vulnerable. At the same time, Kathmandu has one of the highest urban growth rates of all cities in Asia, and much of the urban expansion is occurring in flood-prone areas.

Although in many ways, the situation seems dire, residents of Kathmandu have long been knowledgeable about yearly flood patterns and sustainable urban development. Some of the new valley development plans illustrate that there is potential to adapt traditional water storage systems to solve the modern problem of urban flooding. For example, KVDA’s New Town plans include designs for a series of riverside ponds that can be filled during high water periods to prevent excess water from flowing downstream and causing damage while also facilitating groundwater recharge. This stored water will be released during the dry season to maintain continuous river flow.

For life in Kathmandu to remain viable, as urban flooding is one of many threats to the sustainability of the city, the current processes of haphazard and uncoordinated development must be replaced by environmentally friendly practices that also maintain local customs and culture.

(Purnima Acharya helped research for this  opinion article)

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