From ungauged to informed: combining community observations, a citizen science app, and hydrological modeling to estimate mountain streamflow

Knowledge of the flow regime of streams and rivers is fundamental for assessing their ecological resilience and impacts from human activities and climate change. However, for many streams, especially those in remote mountain areas, streamflow data are lacking. For ungauged catchments, citizen science and participatory action research methodologies can be used to generate the needed streamflow data. The CrowdWater (www.crowdwater.ch) app can, for example, be used to record observations for different hydrological variables. Repeated observations of the relative stream water level or the presence of water and flow in intermittent streams can provide data for otherwise ungauged catchments. To demonstrate the usefulness of the CrowdWater app for collecting data on streamflow in a marginalized mountainous community setting, this presentation will highlight a case study in the Queuco catchment in Chile. The catchment is located in the indigenous Mapuche-Pehuenche territory. Due to threats related to water rights, it became urgent for the local communities to obtain reliable hydrological data. Therefore, the communities observed stream water-levels using the CrowdWater app. The community co-designed the research objectives and selected the monitoring sites, while the researchers organized the initial training workshop and provided ongoing support. The data were used in a lumped hydrological model (HBV) to obtain estimates of the streamflow, which were then compared to historic monthly data (1938 – 1970). The model results suggest that even though there are no dams or water abstractions yet, the natural flow regime has already changed, with reduced flow throughout the year, and especially in October and November, likely due to declines in snowmelt. Overall, this case study highlights the usefulness of a citizen science app in participatory action research to collect data on the natural flow regime, which can be used in other (mountain) catchments with pressing issues related to water availability and security as well.