Assignment #6

Behera, P, Papa, F., Adams, B (1999) “Optimization of Regional Storm-Water Management Systems” Journal of Water Resources Planning and Management, 125(2) pp. 107-114.

Summary:
In this article, the authors discuss their use of optimization techniques to calculate the required geometry for the detention ponds in a watershed on a system-wide scale in order to ensure the discharge at the outlet met quality and flow requirements while minimizing the overall cost of building all the detention basins. For each basin, the authors used decision variables representing the storage volume, depth, and release rate for each pond. Constraints included the pollution reduction and the runoff control performance. The authors used isoquant curves (developed by Papa and Adams in 1997), which show the pollution control of a detention pond as a function of the ponds storage capacity and release rate.

In order to optimize the entire system, individual detention basins were allowed to discharge water that didn't meet flood attenuation or pollution requirements, as long as the requirements were met at the outlets. This allowed them to minimize the cost of all of the detention basins since the various detention basins each had different construction and real estate costs. Using their methods, the authors were able to reduce the cost of constructing detention basins for a system containing three basins by $100K.

Discussion:
I thought this was a very well written article explaining the authors' use of optimization for a practical problem which water resource engineers are having to solve all the time. I found the isoquants to be an interesting solution to the problem of modeling the water quality.

The methods used in the paper could be a valuable tool for city governments and developers developing huge tracts of land. I wonder whether having some basins releasing higher quality water and some releasing lower quality water would be permitted by the ordinances and standards regulating discharges.