Optimization of the rainfall-runoff response in urban areas by using controllable drains

Abstract

In the last times, infiltration facilities to reduce the load on the drainage systems have been introduced in many urban areas. These facilities allow water to infiltrate or to drain depending of the level it reaches in the ground. It results easy to conclude that this infiltrating and draining process is likely to be controlled in real time so extra storage can be created on the urban subsurface when necessary or, on the other way round, store water when a shortage is expected. To study the possibilities of controlling the groundwater levels to create extra storage, an area of study was selected in the municipality of Delft, which was interested as well in being able to create extra storage. This area includes an infiltration system. After insight on the area was acquired, the only element which is likely to be controlled in the whole process turns to be the head levels at the infiltration facility. Therefore, it becomes necessary to find the influence the infiltration facility has on the groundwater system on its surroundings and obtain a model which allows tuning a proper controller afterwards. A mathematical model of the response of the groundwater levels within the area of study was created by using system identification. The inputs to this identification process are net precipitation, the historical precipitation and the water level at the infiltration facility. The output is, of course, the groundwater levels. All the data was obtained after a measurement campaign using both “in situ” measurements and remote sensing. Once a proper model was obtained, a simple feedback controller for the infiltration facility levels was tuned. A visible improvement on the groundwater levels behavior was observed when the controlled system was simulated. It results clear then that groundwater levels, within an area where an infiltration facility is present, can becontrolled in theory. A simple actuator was designed and built to be able to run practical experiments in the area later on. With this, the real relation of the infiltration system with the surrounding grounds can be checked as well as different control methods can be tried in further research