Streamflow Forecasting

Dr. Casey Brown

University of Massachusetts

Short–Term Forecasting◦ Predict flows throughout basin on a weekly time step◦ Source of Information: Antecedent basin conditions

and weather forecast

Long-Term Forecasting◦ Predict seasonal flow regimes 3-6 months ahead of

time◦ Source of Information: Climate teleconnections◦ Used to determine which years are strong candidates

to meet inter-annual eco-targets

Short-Term and Long-Term Forecasting

Change in timing of peak flows in NE Rivers

1. Characterize the influence of basin characteristics (e.g., snow) and climate influences (e.g., NAO) on CT River streamflow

2. Develop probabilistic forecasts of streamflow at long lead times (3 – 6 months)

3. Use the “tilt of the odds” to assess conditions for achieving multiple basin objectives

Long-Term Forecasting Methodology

Previous studies have found influence of North

Atlantic Oscillation

Teleconnections to Westfield River

Example: Long-Term Forecasting Application

0.85

0.87

0.89

0.91

0.93

0.95

0.97

0.99

200 300 400 500

Aver

age

% o

f Wat

er S

uppl

y Ta

rget

Minimum Instream Flow (CFS)

Wet

Dry

Normal

Climate in Previous Season Predict Shape of Tradeoff

Better opportunities for meeting eco-targets

Less opportunity for meeting eco-targets

Short-Term Forecasting Use

Weekly Streamflow Forecasts

Optimization ModelSimulation Model

Short-Term System Performance Under

Standard Operations

Short-Term System Performance Under Optimal Operations

Operator Judgment

Plan for weekly operations

Existing River Forecasts

Short-Term Forecasting Methodology

HYDROLOGY MODELS OF

SYE INDEX SITES

METEOROLOGICAL FORECASTS

STREAMFLOW FORECASTS AT SYE

INDEX SITES

SYE ESTIMATION METHOD

STREAMFLOW FORECASTS AT ANY LOCATION IN THE

BASIN!