Nedbørrunoffmodeller

Nedbørrunoffmodeller, or rainfall–runoff models, are hydrological tools that simulate how precipitation becomes runoff in a drainage basin. They help predict river flows, assess flood risk, and support water resources planning by representing the key processes that govern rainfall responses.

Models fall into several categories, including lumped versus distributed approaches, and physically based versus empirical or semi-empirical formulations. Lumped models use aggregated parameters for the entire catchment, while distributed models assign parameters to spatial units and can capture rainfall variability and flow routing.

Physically based models simulate processes such as infiltration, runoff generation, soil moisture storage, and baseflow using parameters with physical meaning; empirical models rely on statistical relationships between rainfall and runoff. Common inputs include rainfall time series, catchment geometry, land cover and soil properties, and observed streamflow for calibration.

Calibration and validation involve adjusting parameters to match observed hydrographs, often using objective functions like the Nash–Sutcliffe efficiency, and may include uncertainty analysis. Well-known examples include HEC-HMS, SWAT, and MIKE SHE, as well as smaller, purpose-built rainfall–runoff models.

Limitations arise from data quality, parameter non-identifiability, scale effects, and model structural assumptions that may not hold under changing climate or land use. Nedbørrunoffmodeller remain foundational in hydrology for predicting runoff responses and supporting flood risk management and water resources planning.