Accounting for Stream–Aquifer Interactions in the State-Space Discretization of the Kalinin–Milyukov–Nash Cascade for Streamflow Forecasting

Abstract

A sample-data system discretization of the continuous Kalinin–Milyukov–Nash cascade is performed in a state-space analysis framework allowing for stream–aquifer interactions that include bank storage during flood events and groundwater discharge to the stream under low-flow conditions. These interactions generally result in faster attenuation of propagating flood waves and in elevated streamflow levels during drought conditions. An example is given that demonstrates how accounting for these processes ensures more reliable streamflow forecasts. The model is based on a simplified physical description of the processes both in the stream and across the stream–aquifer boundary.