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Ephemeral natural channels in cities are reclaimed to provide land for housings and other functions. This is because of limited knowledge about the crucial role played by natural channels in stormwater management. For long, the cities have been dependent upon grey infrastructure to drain out stormwater away from the city. Therefore, it requires a paradigm shift to see the natural channels as a tool for stormwater management. There is a pressing need for the preservation of natural channels because incidences of pluvial flooding are increasing. The inability of existing grey infrastructure to take up the additional stormwater load has forced the planners to think of sustainable alternatives. In this study, the case of accidental preservation of an ephemeral natural channel in Chandigarh city is discussed and analyzed. The symbiotic relationship between Leisure valley (a green belt) and N-choe (a natural channel) offers many learnings in the preservation of natural channels. From careful observations and brainstorming, contributory factors that paved the way for the preservation of the natural channel, the concept of greenswales is evolved. A framework is developed for the sustainable planning of greenswales. It will guide the city planners and managers to have an alternative approach to preserve the natural channels sustainably and use them as a tool for pluvial flood management. This study's significant finding is that ephemeral natural channels in a city can be safeguarded through the judicious superimposition of green spaces over them.

For long, the cities depended on grey infrastructure for draining stormwater. However, incidences of pluvial flooding are increasing, and existing grey infrastructure is unable to take up the additional stormwater load. Consequently, planners are forced to think of new and sustainable alternatives for stormwater management. Natural channels can supplement the stormwater drainage systems, but these channels in cities are reclaimed to provide land for housing and other functions despite their crucial role. This study presents the case of a natural channel in Chandigarh (India) that is redeveloped as a greenspace without compromising its function of stormwater conveyance. We analytically discussed the non-intentional preservation of this seasonal natural channel and introduced a new term, greenswales, for similar arrangements. A greenswale is defined as the stretch of greenspaces laid over a natural channel, ephemeral or intermittent, having stormwater detention and conveyance as primary functions during precipitation. This study's significant finding is that the seasonal natural channels in a city can be safeguarded through the judicious superimposition of green spaces over them. Crucial lessons from this case can guide new developments in utilising natural seasonal channels as a nature-based solution for stormwater management, reducing the load on grey infrastructure and providing the city with a greenspace.