Introduction
Soil moisture sensors were developed by citizen science collective Meet je Stad (Measure your City). Measure your City was started in 2015 by inhabitants of the City of Amersfoort, with the goal of measuring climate related indicators. To be able to do so, collaboration was sought with the City of Amersfoort (COA), the local Water Authority and the University of Applied Sciences of Amsterdam. For the first three years the initiative focused on measuring temperature and humidity. Importantly, citizens develop their own research questions, analyze the data together with professionals and discuss potential implications. By doing so, the collective uses citizen science to spread knowledge on both technology and climate change in the most grass-roots manner possible.
Soil moisture measurement
Within Meet je Stad (Measure your City) soil moisture was measured in order to see how long periods of rain or drought affect the moisture status of the soil. Due to climate change, extended periods of drought and heavy rainfall are increasingly expected in the (near) future. The better the soil is capable of buffering these extremes, the less the negative effects will be on for example plant growth, or damage to buildings and infrastructure in the city.
By investigating how moisture in different soils changes due to rainfall, drought and the type of plants growing on it, we hope to take more targeted measures for climate adaptation, such as enhancing the soil composition or choosing plants that are more drought-tolerant.
The Meet je Stad soil moisture sensor can also be used to measure moisture on green roofs. Whereas the sensor installed in actual soil measures moisture levels at two depths, when installed on a green roof the sensor only measures moisture at one depth.
Data collection
The data collected in the Amersfoort case is transmitted from the sensors to the online environment using two LoRaWAN gateways. Data is sent to this SCOREwater platform once every three hours. Once the data is available on the platform, the data will be harmonized using the FIWARE GreenSpaceRecord FIWARE model. This model contains a harmonized description of the conditions recorded on a particular area or point inside a greenspace (flower bed, garden, etc.), like soil temperature or soil moisture. The Measure your city soil moisture sensors measure soil moisture using conductivity.
