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Storm water management in Guadalajara

Poppema, Daan (2014) Storm water management in Guadalajara.

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Abstract:Guadalajara is the second city of Mexico, with more than 4.5 million people. Every year, floods cause over 30 million euro of damage, pollution, health problems, structural damages and sometimes even loss of human lives. To solve all these problem, additional knowledge on the bottlenecks in the hydrologic system and possible solutions is needed. To generate this knowledge, IITAAC has built a hydrologic model of a part of the San Juan de Dios subbasin, a river basin in the centre of the city. This model consist of two situations: the actual, current situation and a scenario with proposed measures to decrease the problems. The objective of the research was to improve the existing hydrological model of Guadalajara, migrate it from EPA SWMM to PCSWMM and use it to propose new solutions for storm water management in Guadalajara. The validation process used to improve the model started with a sensitivity analysis. After this, Sargent’s framework of the modelling process was used for validating and improving the model. This means that the modelling process was divided into the internal quality, data quality and output quality. The first step of the validation was a sensitivity analysis. This showed that the results are especially sensitive to junction depth, conduit depth and outfall elevation. These are aspects where checking the data is important. However, it is difficult to obtain more data, which makes conclusions less reliable. Checking the internal validity resulted in several changes to the model. Storage units have been lowered to enable them to fill up and the initial volume of El Dean has been lowered. The size of conduits has been changed at some points, most importantly between El Dean and its outfall. Junctions have received a pondable area to make sure that when they flood, no water is lost from the system. And corrections to their elevation have resulted in the elimination of bottlenecks. Validation of the output is difficult due to a lack of data for the real situation. However, some remarks can be made. The model seems to underestimate flooding around El Dean and the Canal del Sur. Without modelling the current situation correctly, it is unlikely that the exact effects of measures can be calculated correctly. The consequence is that the model should mainly be used for comparing the effectiveness of measures. Designing measures and assessing their results on an absolute scale would require a more exact model. For the actual situation, improving the model did not significantly change the maximum volume of flooding, it decreased flooding after 24 hours from 70 percent to 35 percent of the total rain volume, it made storage units function better and increased outflow. For the situation with proposed measures, mistakes with the surface storage and an unrealistic low outfall dominated the results. The measures seemed to result in a 25 percent decrease of runoff and a total absence of floods. Correcting this lead to a more natural situation with outflow, floods, storage and infiltration. Concerning the impact of the measures, the proposals decrease the total occurring flood volume from 75 percent to 45 percent of the rain. Even more impressively, flooding after 24 hours decreases from 30 percent to less than 5 percent of the total rain volume. However, as upstream flooding is decreased, more water flows to the downstream part of the subbasin. This causes El Dean to flood more. Furthermore, the decrease and flooding and increase in outflow is good for this subbasin, but it can cause problems in downstream areas.
Item Type:Essay (Bachelor)
IITAAC (Instituto de Investigaciones Tecnológicas del Agua), Guadalajara, Mexico
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering BSc (56952)
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