The pollution in the river Arno downstream of the city of Florence is a sev
ere environmental problem during low-flow periods when the river flow rate
is insufficient to support the natural waste assimilation mechanisms which
include degradation, transport, and mixing. Forecasting the river flow rate
during these low-flow periods is crucial for water quality management. In
this paper a neural network model is presented for forecasting river flow f
or up to 6 days. The model uses basin-averaged rainfall measurements, water
level, and hydropower production data. It is necessary to use hydropower p
roduction data since during low-flow periods the water discharged into the
river from reservoirs can be a major fraction of total flow rate. Model pre
dictions were found to be accurate with root-mean-square error on the predi
cted river flow rate less then 8% over the entire time horizon of predictio
n. This model will be useful for managing the water quality in the river wh
en employed with river quality models.