How well can citizens observe water levels using a smartphone app, and when do they choose to do so?

Abstract:

One possibility to overcome the lack of data in hydrology is to engage the public in hydrological observations. Citizen science projects are potentially useful to complement existing observation networks and to obtain spatially distributed stream-data. Hydrological citizen science projects have, so far, been based on the use of different kinds of instruments or installations. For stream level observations, this is usually a staff gauge. While it may be relatively easy to install a staff gauge at a few river sites, the need for a physical installation makes it difficult to scale this type of citizen science approach to a large number of sites because these gauges cannot be installed everywhere or by everyone. Here, we present the CrowdWater smartphone app that allows the collection of hydrological data without any physical installation or specialized instruments. The approach is similar to geocaching, with the difference that instead of finding treasures, hydrological measurement sites can be set up. These sites can be found by the initiator or other citizen scientists to take additional measurements at a later time. Instead of a physical staff gauge, a virtual staff gauge approach is used: a picture of a staff gauge is digitally inserted into a photo of a stream bank or a bridge pillar. During a subsequent field visit the current stream level is compared to the staff gauge on the first picture. In this presentation, we discuss how well the water level class observations agreed with measured stream levels and in which months and during which flow conditions, citizens submitted their stream level observations. We furthermore highlight methods to ensure data quality, and illustrate how these data can be used in hydrological model calibration.