Isn't retaining and storing water by definition at odds with one another?
This is the commonly accepted view. Following the principle of 'full is full,' the water in an area used to store water from periods of peak rainfall will have to be drained as quickly as possible in order to store water for the subsequent flood peak. As part of this project, we wanted to investigate whether it is possible to retain stored water for as long as possible in the storage area after a peak discharge, so that the water can be purified on-site from nitrogen and phosphate and the clean water can be reused. RichWaterWorld is demonstrating that it is possible to predict a subsequent flooding problem in a timely manner by using a smart combination of prediction models and sensor-fed information about groundwater, water levels, and soil moisture content. With this approach, the water authority can retain the water under its management for as long as possible in the water storage area. This water can be used as a supplementary supply during water shortages. The water authority can also make a timely decision to release the water into the river if the water storage area must be used to absorb water from a flood peak.
Why is it necessary or desirable to retain water in Park Lingezegen?
Currently, there is no pressing reason to retain water. However, in the key problem analysis which was carried out for 'Deltaprogramma Zoetwater,' the Dutch national freshwater management scheme, it was calculated that there will be water shortages in the period until 2050 in the event of a WL / WH KNMI climate scenario (with 'WL' representing a 2 °C rise in temperatures in West Europe with no changes in air circulation patterns and WH ' representing a 2 °C rise in temperatures with changes in air circulation patterns). This is because the intake of river water from the 'Pannerdens Kanaal' (Pannerden Canal) into the river Linge will have to be regularly discontinued for some weeks in order to allow shipping traffic to sail on the 'Rijntakken' (IJssel river forelands, Neder-Rijn river forelands, Gelderse Poort and Waal). For drought-sensitive crops such as fruit crops in the Betuwe region, and in order to tackle desiccation, the water under the management of water authorities must be retained for longer - in particular in the upstream area 'de Kop van de Betuwe' in which Park Lingezegen is located.
Sensors and Weather Models
How are the measurement data made accessible?
The data provided by the meteorological mast and the sensors in the soil and water are sent to the data platform 'WaterRijkWeb' via telemetric transmission. Once processed, they are visualised in the hydrological model on this website.
Which parameters are monitored?
Two sets of parameters are monitored. The first are meteorological parameters: precipitation, wind speed, wind direction, air pressure, air temperature and relative humidity. The second are hydrological parameters: surface water level, soil moisture content, pF, groundwater levels (phreatic and in the aquifers).
Precipitation forecasts are never right: how can you formulate and apply scenarios for these?
One single forecast, which is based on one single source, such as a weather model or a radar image, will never be fully correct. Rainfall is unpredictable; showers can arrive later or follow a different course. The amount of precipitation from showers can vary within short distances. However, by combining several models and integrating radar images with the calculations from weather models, it is possible to produce a probability forecast for rainfall that is subdivided into three categories: it will stay dry, there may be some rainfall or peak rainfall is expected. Each category is analysed by the hydrological model. The water authority can then decide whether additional management measures are necessary on the basis of the probability calculations and the results from the hydrological model.
Are there ever drought conditions in a reed bed?
Reed beds require a certain groundwater level/water level on which the reeds can grow. This means that these areas never become really dry. However, good-quality water will have to be fed in during drier periods. To achieve this, it is important that the water stored in the area is purified so that 'local' water can be used during a dry period. Analysing and forecasting dry periods determines how much water must be stored during a wet period.