Data_Sheet_1_Monitoring of Suspended Sediments in a Tropical Forested Landscape With Citizen Science.xlsx

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 (R2 > 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. 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.

流域（catchment）是一类复杂的水文系统，需对其水化学参数开展时空常规监测，以获取全面数据集。此类数据可用于表征流域的局地行为特征、基于模型开展未来情景预测、落实生态减缓措施并达成相关政策目标。然而，诸多发展中国家缺乏完善的水文监测基础设施——因其建设成本高昂，且所需资源往往难以获取。为解决肯尼亚等数据匮乏地区面临的此类难题，参与式公民科学（participatory citizen science）方法可成为水资源监测的可行策略。

本研究评估了采用贡献式公民科学方法，探究肯尼亚西部松杜-米里乌流域（Sondu-Miriu river basin）时空浊度与悬浮泥沙动态的潜力。研究团队培训了19名公民科学家，使其可借助浊度管（turbidity tubes）与水位计（water level gauges），在松杜-米里乌流域的6个嵌套子流域（nested subcatchments）内开展浊度与水位监测。在项目实施周期内，共有37名公民科学家参与其中，共同贡献了整套浊度数据集。各年度的采样工作量与数据贡献量存在差异，不同参与者间亦有区别：72%的数据仅来自占总人数22%的8名公民科学家。

将公民科学家采集的悬浮泥沙数据与自动监测站（automated stations）的实测数据进行对比后发现，二者具有极高相关性（决定系数R²>0.9），这表明公民科学家采集的数据可与昂贵专业监测设备获取的数据相媲美。不过，在低浓度与高浓度区间内，悬浮泥沙浓度的测量精度有所下降，这主要源于浊度管的检测局限性，以及公民科学家未能捕捉到主要的泥沙输运事件。

相较于森林植被覆盖度较高的子流域（50±24.7 mg L⁻¹），以农业与牧场为主、森林植被覆盖度较低的下游子流域的悬浮泥沙浓度显著更高（109±94 mg L⁻¹）。该结果表明，森林覆盖是管控该区域悬浮泥沙浓度的关键景观特征。

未来的公民科学项目应聚焦于激励与参与策略，并采用具备更高检测限与分辨率的稳健方法，以推动水文监测工作的进一步发展。