The U.S. Army Corps of Engineers is responsible for operating several hundred reservoirs throughout the United States. Many of the reservoirs are multiple purpose, with flood control as a primary purpose. Day-to-day operational decisions are generally made in water control centers located in the Corps' district offices. Some of these offices utilize a water-control software system developed by the Hydrologic Engineering Center (Pabst and Peters, 1983), which facilitates the decision-making process with capabilities for processing meteorologic and hydrologic data, forecasting runoff and simulating reservoir system performance. A component of the software system is computer program HECIF (Peters and Ely, 1985), which performs runoff forecasting. The focus of this paper is on application of HECIF in making short-term (3 to 5 day) forecasts for the 11,733 square mile (30,440 sq. km.) Allegheny River Basin, which contains nine flood control reservoirs operated by the Pittsburgh District, Corps of Engineers. Following a brief overview of the nature and scope of the water control software system, the intended application of HECIF is provided. The characteristics of the Allegheny Basin, data collection networks, and forecast needs are described, as well as the approach used for model calibration and initial results. Finally, comments are made regarding the present status of model development and usage, and plans for the future. (fr).

The Corps' Hydrologic Engineering Center (HEC) has developed a generalized simulation model capable of analyzing complex river-reservoir systems. The development of the model, 'HEC-5, Simulation of Flood Control and Conservation Systems' (Eichert, 1974, 1975) has been paced by the changing mission of the Corps as well as the evolution of computer systems. HEC-5 development and management, including code development, testing, documentation, training and field application experience, is discussed. (fr).

Published by the American Geophysical Union as part of the Water Science and Application Series, Volume 6. During the past four decades, computer-based mathematical models of watershed hydrology have been widely used for a variety of applications including hydrologic forecasting, hydrologic design, and water resources management. These models are based on general mathematical descriptions of the watershed processes that transform natural forcing (e.g., rainfall over the landscape) into response (e.g., runoff in the rivers). The user of a watershed hydrology model must specify the model parameters before the model is able to properly simulate the watershed behavior.