Moscow megacity is experiencing the largest net population growth in Russia and across Europe, resulting in significant climatic and hydrological changes of the small rivers. High-frequency (30-min) automatic streamflow and sediment monitoring with turbidity sensors was performed in 2019-2024 across the Setun River-the major tributary of the Moskva River, with a 190 km2 catchment area. It was also enhanced with 8 detailed records by the in-situ LISST-200x laser diffractometer, spanning 49 h from February to April 2024.

The geospatial analyses of the catchment revealed up to 40 % distribution of impervious surface types, which determines a novel streamflow regime. Its main features are frequent short-term peak flow events, up to 29 per year, and a short flood wave catchment response to rainstorms. Downstream increase in residential area density and impervious surface area from upstream to downstream areas does not affect the relative contribution of various water sources, whereas a 3-4-fold increase in suspended sediment transport conditions along the river is registered.

Short-lived increases in suspended particulate matter (SPM) concentration and grain sizes are characterized by hysteresis effects due to hydraulic sorting of suspended sediments along the river channel downstream of the local pollution sources. Finally, we developed a robust and novel methodological approach for forecasting suspended sediment concentrations from water level and flow, precipitation, and air temperature in a fluvial urban system by adopting 5 machine learning models with a resolution of 30 min to 1 day. The best results were demonstrated by the recurrent neural network LSTM for daily water turbidity values with a root-mean-square error of 10.8 NTU.

Chalov, S., Denisova, I., Moreido, V., Solonikov, I., Loshkov, O., Botavin, D., Samokhin, M., Chalova, A. and Kasimov, N. (2026). Streamflow and sediment dynamics affected by precipitation events and land use changes in the heavily urbanized small catchment of Moscow megacity. Urban Climate, [online] 65, p.102745. doi: https://doi.org/10.1016/j.uclim.2025.102745