Assignment #7 - Infiltration Based BMP Optimization

Review Article

1) Article Reference
Perez-Pedini C, Limbrunner JF, Vogel RM (2005) “Optimal location of infiltration-based best management practices for storm water management,” JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT, 131(6) pp. 441-448

2) Summary
This paper presents an approach to optimize the location of infiltration based best management practices to reduce peak flow during storm events. According to the author many optimization applications were previously developed to find optimal location, design and operation of detention ponds in a watershed to reduce peak flow.
The infiltration based best management practices considered are infiltration basins, rain gardens and pervious pavements. The approach to integrate a wide variety of distributed storage and infiltration storm water controls acting in combination have been called as low impact development (LID).
According to the author the major goal of this study is to introduce a methodology to determine the optimal number and location of infiltration based practices to reduce peak flow. It was used a fully distributed model based on the SCS curve number approach. The model was applied to the Aberjona River watershed. This model was programmed in excel and VBA with a system of 4533 square HRUs that have a side length of 120 m. It was used the D8 algorithm for runoff routing. A detailed description of all mathematical formulas used to model the water movement within the distributed model was presented. This model was then calibrated for a storm event using 15 min storm data from two rain gages and compared with a flow gage at the watershed outlet.
The optimization routines were developed using excel and a commercial available Genetic Algorithm optimizer called Evolver. The overall goal of the optimization was to locate the HRUs which if BMPs were applied, would lead to a maximum reduction of peak flow. Some restrictions were applied in order to reduce the feasible space. The author also provided some details of the constraints used in the Genetic Algorithm programming.
As the main results the authors showed a Trade off curve between the reduction of peak flow and the number of best management practices to be implemented. The optimum locations were also presented in maps showing its location within the watershed. The authors concluded that a GA algorithm with a distributed hydrologic model presented satisfactory results for finding the optimal locations and quantity of BMPs to reduce peak flow.

3) Discussion
These papers are getting better and better to read. This one was especially nice as it is easy to understand and I am more familiar with the concepts used throughout the research. I think the authors had a good idea developing this application as it seems a new approach using consolidated methods. This is quite encouraging as I am feeling that the amount of my understanding of the article is increasing significantly.