for example the stormwater zoning plan aims to i limit the amount of stormwater discharge into the river seine ii minimise the stormwater that overflows wastewater control plans and hi prevent flooding in the city the purpose of the zoning plan is to provide urban planners and construction operators with recommendations and guidelines on new alternative techniques these will include green roofs gardens lagoons and other green spaces to encourage reuse and filtration of stormwater and to coordinate decision making in urban stormwater management processes the aim is to collect the first inch of rainfall on of the impermeable areas over the next years when it rains in new york city the most densely developed city in the united states a vast amount of runoff from rooftops streets and other impervious surfaces is produced if the key cause of runoff impervious surfaces is not kept in check the dep will have to spend more on tanks and tunnels to store stormwater flows which will further swell with climate change