Rain Barrel-solution for flooding
Introduction
This was a group project aimed at analysing the flooding in Enschede (Netherlands) using spatial information systems and developing an intervention for the stakeholders.
In Enschede, multiple initiatives have been undertaken by the municipality, however, some of the areas remain vulnerable to flooding.
The municipality has mainly focused the flood mitigation measures on public property.
However, due to limited space on the public property to store water, the municipality is looking into initiatives that can be implemented on private properties
Flood simulation from OpenLISEM of Enschede in 2021
Elevation
Digital Elevation Model (DEM)
The difference in elevation contributes to water overflow because during flooding events water flows from a higher elevation to a lower one.
Therefore, we used LiDAR data to create a digital elevation model (DEM) to determine the terrain of the area of interest compared to other parts of the city.
Watershed
Besides the visualization of the terrain, the water drainage of Enschede was studied by creating a watershed map in combination with the 3D terrain to identify where the watersheds in Enschede are located and if the target area lies within one of these watersheds.
Stakeholders Analysis
Climate adaptation projects can be best planned and implemented effectively with the involvement of the public.
The integration of stakeholders within the problem definition and intervention formulation contributes to a more feasible result that has been evaluated by the parties involved.
The stakeholders' influence and importance were determined based on the occurrence of certain stakeholders within the neighborhood and their influence on the implementation of interventions on private property.
Rain barrel intervention
Rain barrels were chosen as the most effective intervention after weighing the advantages and disadvantages of possible interventions.
The alternative interventions considered were green car parks, rainwater storage below buildings, and green roofs.
We designed a multi-functional rain barrel which is disguised as a bench. This simple bench design contains rainwater storage of just over 1200L underneath the seating area, as well as additional room for air to prevent suction.
The intervention is made of plastic to stay durable in the Dutch climate and can be directly connected by a pipe to the gutter system of buildings. At the top, a filter can be placed to avoid clogging of the pipe caused by leaves. A tap is added at the bottom side of the bench, which can be used to release excess water.
Calculations showed that 22% of rainwater can be collected due to the designed intervention. By storing a certain amount of water, it is taken out of the routine for a certain amount of time. By storing 254,531 liters of rainwater the risk of flooding is reduced.
Flood Modelling
A flood modeling in OpenLISEM was created to study the effect of historic urbanization on the flooding problem in the area for different rainfall intensities.
The model was run to determine the rainfall level at which flooding occurred.
Based on the input datasets, the model showed that flooding occurs in the target area for a rainfall intensity of 70 mm/hour.
The hydrograph and flood simulation before the intervention
The model was also used to assess and evaluate the functionality of a possible intervention.
This was done by implementing the intervention(s) within the OpenLISEM model and running the same rainfall model to observe if the flooding in the neighborhood has decreased.
The hydrograph below shows that after one hour of rainfall, the discharge is decreasing very fast. The water levels are not staying high, so therefore it will be a lot less likely for a flood to occur.
The hydrograph and flood simulation after the intervention