Elevation challenges

The flow of the original course of Leo Kong Canal was based on gravity, but since we decided to focus on only one part of the old canal, we had to find an alternative course for part of the project area. Since we cannot trust that there is any reliable flow through the existing underground canal, we thought we could take water from the river a bit further downstream compared to the original canal.

The trip to Taipei revealed some technical challenges and one of them was that the chosen course of the canal was blocked by a military area and that, what used to be an open space, now is a construction site. This meant that we had to expand the area in order to be able to treat the water taken from the river appropriately. 

The new addition to the area, marked orange in the map below, was chosen for its park that could be converted to contain a wetland. However, there is an issue with the elevation differences of the area. 

 

This map points out the highest point along the flow, in the red circle. A solution has to be found for getting the water from the river to the highest point (in the red circle), but still be surfaced, as this area (marked with orange) is the most suitable for wetlands due to restrictive space available in the area that tilts the right way (market green).

The sketch below is a suggestion for the first part of the canal that will take the shape of a wetland area on the river bank. We do not yet know how often floods reach the height of the flood wall, but we do know that there are plenty of recreational areas on the flood bank, such as a small golf course and other sports facilities. This gives us the motivation to put a wetland here despite the risk of floods. Still, the structure should be designed either to withstand a flood or two in its lifetime, or to be rebuilt easily after a flood.

So far, the solution consists of a submersed pump of some kind that takes water from the river and pumps it into an underground aeration tank. Another pump will transport the aerated water to a gravel filter, which will reduce the amount of bacteria and other microorganisms in the water before letting it into the wetlands.

 

Once on the other side of the flood wall, we still need to elevate the water further, as the park where we would like to continue the wetland area to continue is tilting the wrong way. A first thought of how to solve the problem is shown in the sketch below.

The water would be pumped into the first pond, which is above ground level. As the water flows along at a small decline, the ground level approaches the water level. Somewhere in the middle the water and the ground level will be the same and at the end, the wetland will be in a bit of a valley, where the ground level is higher than water level.