Testing of an Optimization-Simulation Model for Real-Time Flood Operation of River-Reservoir Systems

Hasan Albo-Salih,Larry Mays

doi:10.3390/w13091207

Abstract

A new methodology was developed for the real-time determination gate control operations of a river-reservoir system to minimize flooding conditions. The methodology is based upon an optimization-simulation model approach interfacing the genetic algorithm within MATLAB with simulation software for short-term rainfall forecasting, rainfall–runoff modeling (HEC-HMS), and a one-dimensional (1D), two-dimensional (2D), and combined 1D and 2D combined unsteady flow models (HEC-RAS). Both real-time rainfall data from next-generation radar (NEXRAD) and gaging stations, and forecasted rainfall are needed to make gate control decisions (reservoir releases) in real-time so that at time t, rainfall is known and rainfall over the future time-period (Δt) to time t + Δt can be forecasted. This new model can be used to manage reservoir release schedules (optimal gate operations) before, during, and after a rainfall event. Through real-time observations and optimal gate controls, downstream water surface elevations are controlled to avoid exceedance of threshold flood levels at target locations throughout a river-reservoir system to minimize the damage. In an example application, an actual river reach with a hypothetical upstream flood control reservoir is modeled in real-time to test the optimization-simulation portion of the overall model.

Highlights

Flooding is a critical issue around the world, and the lack of comprehensive knowledge of watershed hydrology and tools for the real-time operation of river-reservoir systems can result in a lack of lead-time for flood warning and expensive harm to property as well as life
An optimization/simulation model wasdeveloped to determine the optimal operation of gates before, during, and after flooding events
The proposed optimization-simulation model approach consists of four individual models: a rainfall forecasting model, a rainfall–runoff model, a combined (1D/2D) unsteady flow model, and an optimization model solved using genetic algorithm

Summary

Introduction

Flooding is a critical issue around the world, and the lack of comprehensive knowledge of watershed hydrology and tools for the real-time operation of river-reservoir systems can result in a lack of lead-time for flood warning and expensive harm to property as well as life. Che and Mays [2,3] developed a modeling approach consisting of five major components: (1) the U.S Army Corps of Engineers (USACE) Hydrologic Engineering CenterHydrologic Modeling System (HEC-HMS), which simulates rainfall–runoff processes of watershed systems; (2) the U.S Army Corps of Engineers Hydrologic Engineering CenterRiver Analysis System (HEC-RAS) for 1D unsteady flow routing; (3) a reservoir release operation model; (4) a short-term rainfall forecasting model to project rainfall over the few hours during a rainfall event; and (5) the genetic algorithm (GA) optimizer in. Neither of these two models interfaces optimization and simulation to solve an optimal control problem for determining real-time gate control operations of river-reservoir systems None of these more recent forecasting risk-based models have the capabilities of the model described as illustrated in the model formulation described below

Model Formulation

Optimization Model

Unsteady Flow Simulation Model

Short-Term Rainfall Forecasting Model

Example Application

Conclusions