Estimation of soil moisture content using Citizen observatory data -lessons learnt from GROW Observatory project

Soil moisture is a crucial factor for agricultural activity, but also an important factor for weather forecast and climate science. Despite of the technological development in soil moisture sensing, no full coverage global or continental or even national scale soil moisture monitoring system exist.  There is a new European initiative to demonstrate the feasibility of a citizen observatory based soil moisture monitoring system.  The aim of this study is to characterize this new monitoring approach and provide provisional results on the interpretation and system performance.

GROW Observatory is a project funded under the European Union’s Horizon 2020 research and innovation program. Its aim is to establish a large scale (>20,000 participants), resilient and integrated ‘Citizen Observatory’ (CO) and community for environmental monitoring that is self-sustaining beyond the life of the project. This article describes how the initial framework and tools were developed to evolve, bring together and train such a community; raising interest, engaging participants, and educating to support reliable observations, measurements and documentation, and considerations with a special focus on the reliability of the resulting dataset for scientific purposes. The scientific purposes of GROW observatory are to test the data quality and the spatial representativity of a citizen engagement driven spatial distribution as reliably inputs for soil moisture monitoring and   to create timely series of  gridded soil moisture products based on citizens’ observations using low cost soil moisture (SM) sensors, and to provide an extensive dataset of in-situ soil moisture observations which can serve as a reference to validate satellite-based SM products and support the Copernicus in-situ component. This article aims to showcase the design, tools and the digital soil mapping approaches of the final soil moisture product.