Graduation of Pablo Sanchez Gomez

14 December 2018 13:00 - Location: Room 0.96, Faculty of Civil Engineering and Geosciences - By: Webmaster Hydraulic Engineering

"Risk-based Optimization of Reservoir Emergency Operations" | Professor of graduation: Prof. Dr. ir. S.N. (Bas) Jonkman (TU Delft), supervisors: Prof. Dr. ir. P.H.A.J.M. van Gelder (TU Delft), Dr. J.D. Bricker (TU Delft), Dr. A. G. Sebastian (Rice University), Ir. K.T. Lendering (Horvat & Partners), Ir. E.C. van Berchum (TU Delft).

As population levels protected by large dams have risen in the last decades, accurately
assessing flood hazard and risk will become increasingly important for developing and sustaining flood mitigation policies. Recent research has shown that the degree of control and protection offered by retaining structures largely depend on their operation strategies. As such, now, more than ever,  it  is  crucial  to  be  prepared  to  operate  a  reservoir  under  extreme hydrological circumstances, when the consequences of an operational error could be very serious. However, the  operation  schedules  currently  use  in  the  engineering  practice  lack  on  mechanisms  for evaluating and balancing the potential risks associated with storage and release decisions. This results in reservoir flood control strategies that, from the perspective of flood risk mitigation, are distant from the optimal. This graduation project aims to improve existing methods for developing  emergency  operation  schedules  by  including  the  concept  of  risk  into  the optimization of flood control operations.

To address this topic, the research is divided into: (1) development of a methodology for including reservoir operation effects in the risk analysis of dam-reservoir systems; (2) combination of the risk analysis procedure with an optimization algorithm to devise optimal risk-based emergency operation schedules.The thesis culminates with a case study in which the emergency operations are optimized for the Barker Reservoir system in Houston, Texas. Susceptible to Hurricanes like Hurricane Harvey (2017) and intense precipitation events such as Tax Day (2016), the Barker system presents an operational dilemma requiring trade-offs between released flows and stored volumes. Using the methods developed in this thesis, the flood risk analysis shows that a change in the operational strategy  would  contribute  greatly  to  reducing  the  total  risk  of  the  system.  Under  extreme hydrological events, an operation strategy with releases starting at the first stages of the flood event display a reduction of almost a 32% on the total risk of the system as compared with the current operation strategy, including a 40% decrease on the risk associated with the structural failure of the dam. The new operating policy, however, increases the frequency of downstream damages during non-structural low frequency failure scenarios. Therefore, an increase of the downstream channel capacity along Buffalo Bayou and adequate measures to strengthen the dam are further recommended to reduce downstream damaging flooding and diminish the failure probabilities of the structure.