The idea behind this project is to build a dense network of hydro-meteorological monitoring stations in sub-Saharan Africa; one every 30 km. This asks for 20,000 of such stations. By applying innovative sensors and ICT, each station should cost not more than $2,500. The stations are placed at schools and integrated in the educational program. The data is combined with models and satellite observations to obtain a very complete insight in the distribution of water and energy stocks and fluxes. Within this process we are continuously working with students and researchers on designing and testing new and innovative ways to improve measuring climate variables in a low cost way.
The sensors to be used in this type of weather stations need to be robust against dust and insects. The use of moving parts should be avoided, as this requires more maintenance and increases the risk of failure. Currently, we are working on rainfall measurement using an acoustic disdrometer. Also referred to as “measuring rainfall by the beat of the drum”.
After testing several potential candidates, we settled on a very simple piezo ceramic element, which measures the impact of single drops. Such an element costs around $1. The impact of each drop causes an acoustic signal that is transformed into a voltage. Further testing consisted of comparisons during rainstorms between the acoustic disdrometer and standard tipping bucket raingauges. During intensive storms, the acoustic disdrometer gave results that were very close to those of a nearby totaling raingauge. The signal of the tipping bucket raingauges was clearly saturated as these were not capable of keeping up with the rain. During low intensity events, tipping bucket raingauges performed better as drops too small to detect by the acoustic disdrometer became a significant part of the total rainfall.