Transcript of Blue-green networks explained video
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[Animated video: View of houses on a hill and over the sea in the background we can see the Sky Tower. It is raining.]
Voice: When it rains, water travels from the top of a stormwater catchment down to the sea.
[Video: Images that show water on the surface of the ground, under bridges and running between houses.]
Voice: On its journey water travels over the ground as overland flow, through pipes and road culverts, and along channels and streams.
[Video: View of the houses on the hill with rain creating flooding reaching some houses.]
Voice: In very heavy rain or intense downpours, the amount of stormwater can exceed our pipes and streams’ capacity and flood our communities.
[Video scene 1: View of flooded farmland and buildings surrounded by water, with animals in the foreground and in the distance on a hill above the water. It is still raining heavily.]
[Video scene 2: View of a street with houses. Water moves down the street toward a stormwater drain and beginning to flood the street and the nearby houses. The rain eventually stops and the sun comes out.]
Voice: Due to climate change increasing the frequency and size of storm events, many houses in low-lying areas and flood plains are now at increased risk of flooding. While more or larger pipes may resolve some issues, it's not always possible or cost effective to do so. We need to make more space for water to flow safely through our neighbourhoods without causing risk to people and property.
[Video: View of parkland with houses nearby and a large stream flowing past the houses but not reaching them. The rain stops and as the sun comes out the stream gets smaller.]
Voice: Creating blue-green networks is one way we can do this. A blue-green network is the creation of open parkland within the floodplain of a stream to better carry rainwater during a storm, diverting it away from neighbouring buildings. During dry weather, the park functions as normal for the community to enjoy.
[Video: View of a desk with blueprints of houses on them with a stream flowing between them. A person circles some of the houses using a white pen.]
Voice: To create a blue-green network, some buildings may need to be removed to create the park and widen the stream. Usually, these are houses with a high flood risk, but not all houses that flood need to be removed, and some houses that don’t currently flood may need to be removed for the blue-green network to function properly. Deciding which properties to remove involves looking at the area as a whole.
[Video scene 1: View of houses with a stream running through during a rainstorm. As the rain falls flooding occurs between the houses and the houses touched by the flooding turn red.]
[Video scene 2: The view pans to houses further up the hill beyond a culvert. There are larger floods here touching many houses which turn red. An arrow points toward the culvert which is only letting a small amount of water out.]
[Video scene 3: The view pans once again to the houses with the stream which are now flooded even more. More houses turn red as the flood water reaches them and rises.]
[Video scene 4: All the red houses disappear momentarily. then some of the houses reappear and the path of the stream is changed taking up some of the room made by removing some of the houses. Trees and people appear next to the stream, the culvert is enlarged and the houses beyond the culvert now no longer have any flooding. The rain has stopped.]
[Video scene 5: We see the entire view of the houses with all the changes made. The rain has stopped and people are enjoying the newly created parkland.]
Voice: In this example, all of the properties will flood in an extreme storm that has a one per cent chance of occurring every year – known as a 100-year event. These properties are in a low-lying flood plain close to the stream, which floods when the stream overtops. These properties flood because the culvert downstream is too small and creates a blockage in heavy rain. While increasing the size of the culvert would reduce the flood risk to the properties upstream, it also increases the risk to the downstream properties, so by itself won’t solve the problem. Removing all the properties from a flood plain and surrounding area is costly and disruptive. Instead, by removing a small number of properties and deepening and widening the stream, we could create a blue-green network. This reduces risk for the whole community, particularly the remaining neighbouring homes. The increased water capacity downstream allows the culvert to be expanded safely, helping the upstream houses as well. The planted stream will improve water quality and add ecological value, while the park will be a place for people to use and enjoy.
[Video: The Auckland Council logo appears with the website address 'www.aucklandcouncil.govt.nz/bluegreen'.]
Voice: Visit the Auckland Council website to find out more.
[Video ends.]
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