Event Detail

Event Type: 
Applied Mathematics and Computation Seminar
Date/Time: 
Friday, February 10, 2012 - 04:00
Location: 
GLK 113

Speaker Info

Institution: 
School of Civil and Construction Engineering
Abstract: 

River flooding is a recurrent threat and its control and management continues to be a challenge. It has been recognized that effective flooding control requires a real-time strategy that combines optimization with a simulation model. Current real-time frameworks that combine simulation and optimization have two main drawbacks. The first drawback is that they attain the best operation strategy based on short-time forecasting only (few hours – few days). This may lead to a wrong operation strategy that may result in flooding or to an unnecessary water release from the reservoirs which would be in conflict with non-real time objectives of the system, such as those of maximizing water storage for irrigation and hydropower production. The second drawback is that they do not account for system flow dynamics (current frameworks simply perform mass balance analyses in the reservoirs and neglect the gradients of the water surface). This is a strong limitation given that a flooding event is highly dynamic and may start from anywhere in the river system. It may start from upstream (e.g., large inflows), from downstream (i.e., high water levels at downstream) or laterally from the connecting reaches (e.g., water levels at river junctions are near the reach banks). Accounting for system flow dynamics is also important because the flow conveyance from one reservoir to another is not instantaneous but depends on the capacity of the connecting reaches, the capacity of the associated gates and outlet structures and the dynamic hydraulic gradients. We present a novel simulation-optimization real-time framework that (1) accounts for system flow dynamics and therefore takes into consideration the variability of the antecedent initial and boundary conditions, (2) maximizes the benefits of non-real time objectives of the regulated river system at all times, except during a pre-determined period, during which the objective of the system will switch exclusively to avoiding/minimizing flooding and (3) allows for controlled flooding only after the capacity of the entire river system has been exceeded. Controlled flooding is based on a hierarchy of risk areas based in turn on losses associated with flooding. This means that river reaches (or their areas of influence) that are less prone to losses are assigned higher preferences for locations of flooding. Once the proposed framework determines that there is no further danger of flooding, it automatically switches back to maximizing the benefits of the long-term objectives of the system. An additional advantage of the proposed framework is that it will lead to accurate warning systems that will be activated when the framework finds (ahead of time) that the system will not be able to convey the expected inflows. A successful application of the framework to a hypothetical river system and an actual system will be described in the presentation.