Event Runoff Coefficient Variability in Hydrological Systems

The event runoff coefficient, defined as the ratio of direct runoff to precipitation for individual rainfall‐runoff events, exhibits pronounced variability across spatial and temporal scales. This variability reflects the interplay of climatic drivers, catchment attributes and anthropogenic influences. Climatic factors—including rainfall intensity, duration and seasonality—directly modulate the fraction of precipitation converted to runoff, while geological and soil characteristics govern the partitioning of water between surface and subsurface pathways. Land use and land cover changes further alter infiltration capacities and antecedent moisture conditions, amplifying or attenuating runoff responses. Analysis of hydrographs on an event basis has revealed distinct regional signatures, with some catchments displaying highly attenuated responses and others exhibiting flashy behaviour. Understanding this variability is critical for flood risk assessment, water resource management and prediction of catchment responses under changing climate and land‐use scenarios. Recent advances in statistical learning and large‐sample analyses have begun to unravel the complex controls on event runoff coefficients, offering pathways to more reliable hydrological modelling and improved adaptation strategies.

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Event Runoff Coefficient Variability in Hydrological Systems publication trend

The graph below shows the total number of articles in event runoff coefficient variability in hydrological systems across all publications each year (not limited to Nature Index journals).

Technical terms

Event runoff coefficient (Rc): The ratio of direct surface runoff to rainfall depth for a single rainfall‐runoff event, indicating the efficiency of rainfall conversion to runoff.

Hydrograph: A time series representation of streamflow or runoff rate following a precipitation event, used to characterise event response.

Antecedent soil moisture: The moisture content of the catchment soil before the onset of rainfall, which influences infiltration and runoff partitioning.

Catchment initial state: The set of hydrological conditions (e.g. storage, baseflow) prevailing in a drainage basin at the start of an event, affecting runoff dynamics.

References

1. Unraveling hydroclimatic forces controlling the runoff coefficient trends in central Italy’s Upper Tiber Basin. Journal of Hydrology Regional Studies (2023).
2. Controls on the Spatial and Temporal Patterns of Rainfall‐Runoff Event Characteristics—A Large Sample of Catchments Across Great Britain. Water Resources Research (2023).
3. Annual runoff coefficient variation in a changing environment: a global perspective. Environmental Research Letters (2022).