USING LUMPED PARAMETER DRAINAGE-BASIN MODELS TO ASSESS LAKE LEVEL IN A MANAGED LAKE SYSTEM
Several task are underway associated with the preparation of a simple computer model being prepared to assess factors that influence lake-water level. Anticipated use of this interactive modeling system include: 1) education of groups about the impacts of management options, 2) sensitivity analysis of different parameters used in the model, and 3) short-term forecasting of river discharge and associated lake level based on weather forecasts, potentially to assist in management decisions at the Eel Weir Dam. Completed activities include: 1) monitoring stream discharge to Sebago Lake through stream gaging and installation of water level data loggers, 2) creation of a simple lumped-parameter drainage-basin model based on GR4J (Perrin et al. 2003, J.Hydro. 279:275-289), and 3) development of a preliminary interface to this modeling system allowing interactive access to the model through the Internet. Currently, rating curves for the major streams flowing into Sebago Lake are being developed, allowing the use of continuously monitored stream stage to predict stream discharge rates. These data will be used to calibrate a model for each sub-basin, and stream discharge associated with each sub-basin will be used to estimate inflow into Sebago Lake and calculate lake level.