Abstract:
Catchments are complex systems, which require regular monitoring of hydro-chemical
parameters in space and time to provide comprehensive datasets. These are needed
to characterize catchment behavior on a local level, make future projections based
on models, implement mitigation measures and meet policy targets. However, many
developing countries lack a good infrastructure for hydrological monitoring since
its establishment is costly and the required resources are often not available. To
overcome such challenges in data scarce regions like Kenya, a participatory citizen
science approach can be a promising strategy for monitoring water resources. This
study evaluates the potential of using a contributory citizen science approach to
explore spatiotemporal turbidity and suspended sediment dynamics in the Sondu-Miriu
river basin, western Kenya. A group of 19 citizen scientists was trained to monitor
turbidity using turbidity tubes and water levels with water level gauges in six nested
subcatchments of the Sondu-Miriu river basin. Over the course of the project, a total of
37 citizen scientists participated and contributed to the overall dataset of turbidity. The
sampling effort and data contribution varied from year to year and among participants
with the majority of the data (72%) originating from 8 (22%) citizen scientists. Comparison
between citizen-scientist collected suspended sediment data and measurements from
automated stations showed high correlation (R
2 > 0.9) which demonstrates that data
collected by citizen scientists can be comparable to data collected using expensive
monitoring equipment. However, there was reduced precision of the measurements
of suspended sediment concentrations at low and high levels attributed largely to
the detection limitations of the turbidity tubes and citizen scientists not capturing
major sediment export events. Suspended sediment concentrations were significantly
higher downstream (109 ± 94 mg L−1
), a subcatchment dominated by agriculture
and rangeland with low forest vegetation cover, as compared to a subcatchment with
high forest cover (50 ± 24.7 mg L−1
). This finding indicates that forest cover is a
key landscape feature to control suspended sediment concentrations in the region.
Njue et al. Citizen Scientists Monitor Suspended Sediment
Future citizen science projects should focus on motivation and engagement strategies
and the application of robust methods with improved detection limits and resolution to
advance hydrological monitoring.
