Triple Sensor Collocation can be used to validate 3 independent observations at a location, when the error-free true value is not known. With this you can judge, which water or climate observation, i.e. your citizen observation, conventional station data or a remotely sensed satellite look-up is most reliable.
McColl, K. & Vogelzang, J., Konings, A., Entekhabi, D., Piles, M. & Stoffelen, A. (2014). Extended Triple Collocation: estimating errors and correlation coefficients with respect to an unknown target. Geophysical Research Letters. 10.1002/2014GL061322. [link]
Mannaerts, C.M., Maathuis, B., Wehn, U., Gerrets, T., Riedstra, H., Becht, R. and Lemmens, R. (2017) - Afrialliance Project Report Deliverable 4.4: Constraints and Opportunities for Water Resources Monitoring & Forecasting using the Triple Sensor approach. Available here [link]
About: Demo-app developed for Afrialliance by consortium partner ITC (Faculty of Geo-information Sciences & Earth Observation, Department of Water Resources, UTwente). For more information, pls. contact C. Mannaerts firstname.lastname@example.org, V. Retsios email@example.com and R. Lemmens firstname.lastname@example.org .
The Afrialliance project has received funding from the EU H2020 program under grant agreement No. 689162. For more project info, pls. contact Uta Wehn email@example.com .