Urban aquatic environments
Rivers, streams, lakes, wetlands and estuaries in urban environments can be a real asset to a city. They can also be depressing because they are no longer what we might call "natural". The main impact of urban development is a change in hydrology by altering the flow regimes. This has been done by drainage of wetlands, channelisation of rivers and streams, and covering the land with hard surfaces that reduce infiltration and increase runoff. Engineers, ecologists and planners need to work together to revert to more natural designs incorporating ecological principles.