Rain flow from roof to surface water

Hogeschool_rotterdam_2 28

Hello there

We are working on a school project on the rotterdam university of applied siences, where we have to implement our cllimate adaptive measures in a street in the city. One of my measures is directing the rain waterflow from the roof to the nearest surface water. Can someone help me with connecting a specific hydraulic structure like a culvert from the roof to the surfwace water?

Thank you in advance!

Jarren

Dutch:

Hallo,

Voor een project op school van de hogeschool rotterdam moeten wij onze klimaat adaptieve maatregelen voor een straat doorvoeren in het modelleringsprogramma Tygron, een van mijn maatregelen is het afkoppelen van het regenwater van de daken naar het dichtstbijzijnde oppervlakte water. Kunnen jullie mij helpen hoe ik een hydraulic structure zoals een ''culvert'' verbind met een dak naar het oppervlakte water?

Bij voorbaat dank!

Jarren

Rudolf

Hi Jarren,

There are a couple of properties of a water calculation at work here:

• There is an interpretation of the elevation of the environment, based on both the heightmap and the buildings thereon. Together, this is known as a DSM. There is also a factor at work known as the DESIGN-FLOOD-ELEVATION, which dictates the maximum height at which buildings are interpreted.
• Water flows from grid cell to grid cell based on, among other factors, the elevation on that cell. Water will want to flow from a higher cell to a lower cell (or more exactly, from a cell where elevation + water height is higher to a cell where elevation + water height is lower).
• A culvert can be drawn in the form of a line, from a location A to a location B, to effectively treat 2 distant cells as "adjacent". However, a culvert operates on only a single cell per side of the culvert.

To effectively use a culvert to drain water off a roof, the building would need to function as a retainer with raised edges, so that water stays on it. Then, a culvert can provide an "out" for the water to leave the roof in the direction desired. However, this would be rather invasive to set up properly. If not done correctly, water can simply flow off of the roof before it flows towards the culvert.

A better alternative might be to use a pump instead. Although conceptually a different kind of construction, it can be configured to to the same thing, but can also be set up to operate on an entire area at once (i.e. the entire roof), so that no matter where on the roof the water lands, it has immediate access to a construction which transfers the water to a different location. This may better suit your case in terms of the effects you wish to see.

Regards!