Developing a Typical Rainfall Period for Long Term CSO Analysis in San Francisco, California

Authors: Tsay, Sharon; Brocard, Dominique; Lee, Wallis; Braswell, Greg

Source: Water Practice, Volume 1, Number 6, December 2007 , pp. 1-11(11)

Publisher: Water Environment Federation

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Abstract:

This paper describes the selection and development of a 5-year rainfall period that is currently being used by the City of San Francisco to evaluate sewer flows in a collection system model. The analysis addresses issues such as global climate change and spatial variation during storm events. The long-term rainfall was developed by selecting a 5-year period that closely matched average rainfall records for the past 30 years. The 5-year period was modified by adding and removing storm events to further improve the match to average conditions. The typical period was used to simulate overflows using a calibrated InfoWorks CS model of the San Francisco collection system. The resulting overflows were compared to the numbers that have been reported by the City for the past 20 years. The results of the model simulation indicate that the typical 5-year period closely reflects average overflow performance.

Keywords: RAINFALL ANALYSIS; TYPICAL PERIOD; CLIMATE CHANGE; COMBINED SEWER OVERFLOW; MASTER PLANNING; SAN FRANCISCO

Document Type: Research article

DOI: 10.2175/193317707X269654

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