Eliseo Carrizosa

Safe operation of aging dam infrastructure requires regular updates to design flood estimates and spillway operating rules. This paper presents a semi-automated methodology for updating design floods for return periods of 10 to 10,000 years, utilizing a suite of open-source software tools. The framework was applied to the El Caracol, Infiernillo, and Villita dams within the Balsas River hydroelectric system in Mexico. The methodology is based on the Engineering Institute of National Autonomous University of Mexico (IIUNAM) procedure, incorporating frequency analysis of daily mean flows and the generation of design hydrographs using the AX and IIHIDRODIS programs. Flood routing was subsequently performed under various operational policies using the Trate, HEC-HMS, and Traven programs to develop safe and effective strategies. Key recommendations include: for El Caracol dam, a staggered discharge policy for floods exceeding a 50-year return period (Tr); for Infiernillo dam, limiting discharges to 6000 m³/s during frequent floods (Tr < 100 years) and up to 12,000 m³/s for extreme events; and for La Villita dam, operating at 6000 m³/s, potentially increasing to 10,000 m³/s under extreme conditions while respecting downstream channel capacity. The proposed sequential automation markedly reduces processing times, in particular during the sequence involved in constructing a design flood. Previously, this task required approximately one or two days; it can now be completed in just a few minutes, demonstrating a significant advancement in the state of knowledge for studies on dam safety reassessment.

Se analizaron las variaciones espaciales y temporales del índice de calidad del agua en las tres capas de estratificación térmica en un cuerpo de agua endorreico de Michoacán, México. Se utilizaron dos métodos, el primero es el desarrollado por la Fundación Nacional de Saneamiento de los Estados Unidos de América, que usa nueve variables, físicas, químicas y bacteriológicas, para la estimación del índice. El segundo usa tres parámetros que son recomendados por la Comisión Nacional del Agua en México. El conjunto de datos analizado es una base de datos pública con información de los años 2012 a 2019 en cuatro sitios de muestreo. Los resultados mostraron que la calidad del agua del lago es buena y que en los meses en los que se rompe la estratificación térmica la calidad del agua en el lago es ligeramente mejor que la registrada en los meses de estratificación térmica.

Stochastic dynamic programming (SDP) is an optimization technique used in the operation of reservoirs for many years. However, being an iterative method requiring considerable computational time, it is important to establish adequate convergence criterion for its most effective use. Based on two previous studies for the optimization of operations in one of the most important multi-reservoir systems in Mexico, this work uses SDP, centred on the interest in the convergence criterion used in the optimization process. In the first trial, following the recommendations in the literature consulted, the difference in the absolute value of two consecutive iterations was taken and compared against a set tolerance value and a discount factor. In the second trial, it was decided to take the squared difference of the two consecutive iterations. In each of the trials, the computational time taken to obtain the optimal operating policy was quantified, along with whether the optimal operating policy was obtained by meeting the convergence criterion or by reaching the maximum number of iterations. With each optimization policy, the operation of the system under study was simulated and four variables were taken as evaluators of the system behaviour. The results showed few differences in the two operation policies but notable differences in the computation time used in the optimization process, as well as in the fulfilment of the convergence criterion.