Panama – Joint Reservoir Model Development

Riverside Technology, inc. (RTi), under contract to the U.S. National Weather Service (NWS), has completed a project with the Panama Canal Authority (PCA) to develop and implement the National Weather Service River Forecast System (NWSRFS) to provide a continuous, real-time, integrated hydrometeorological forecast system for the Panama Canal System. As part of the NWSRFS implementation, RTi designed and developed an object-oriented multi-reservoir model for simulating the operation of Gatun and Madden lakes as a single system. This new joint reservoir model, RES-J, was designed and built in the C++ programming language as a stand-alone simulation model. It was incorporated seamlessly as an operation into the FORTRAN-based NWSRFS environment.

Res-J Inflows and Release Hydrographs

Panama’s Gatun Lake comprises almost half of the length of the Panama Canal and was formed by the construction of Gatun Dam across the Chagres River. In addition to serving as travel lanes for ships in the canal, water from Gatun Lake also provides power and municipal water supply. Water enters Gatun Lake from four major rivers and the local lake watershed. In addition to power and water supply, releases from the lake include ship lockages at both ends of the lake and spills over Gatun Dam. Madden Lake was built in 1935 to control floods on the Upper Chagres River and to provide a secondary water supply to Gatun Lake. It also is used for power generation and municipal water supply.

In RES-J, the reservoir system is represented as a network of reservoirs, reaches, and nodes. The RES-J model solves the network from upstream to downstream, one time-step at a time. Loss methods are used to estimate changes to reservoir storage from rain and evaporation. Withdrawal methods estimate discharges that do not become return flow such as municipal supply. Release methods estimate reservoir discharge to the downstream component such as spills or power releases. Water released during lockages of ships transiting the canal is also modeled with a release method for Gatun Lake.

RES-J models both reservoirs and the reach of the Chagres River between them. The PCA uses the output from RES-J to forecast lake levels at both dams. These forecasts are used in decision-making for gate operations and draft restrictions for ships transiting the canal. In 2001, RTi worked with the PCA to develop a model and historical data set for scenario modeling. The PCA uses the system to evaluate alternative reservoir operating policies.

2290 East Prospect Road, Suite 1, Fort Collins, Colorado 80525
phone: (970) 484–7573  fax: (970) 484–7593 www.riverside.com