A Review of Urban Runoff Processes in the Bay Area
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San Francisco Estuary Regional Monitoring Program for Trace Substances A Review of Urban Runoff Processes in the Bay Area: Existing Knowledge, Conceptual Models, and Monitoring Recommendations Lester McKee Jon Leatherbarrow Sarah Pearce Jay Davis SFEI Contribution 66 September 2003 San Francisco Estuary Institute A Review of Urban Runoff Processes in the San Francisco Bay Area: Existing knowledge, conceptual models, and monitoring recommendations 1 Lester McKee, 2 Jon Leatherbarrow, 3 Sarah Pearce, and 4 Jay Davis 1 Watershed Program Manager, 2 Environmental Analyst (Chemistry), 3 Environmental Analyst (Geomorphology), 4 RMP Manager San Francisco Estuary Institute Oakland, CA A report prepared for the Sources Pathways and Loadings Workgroup (SPLWG) San Francisco Estuary Regional Monitoring Program for Trace Substances (RMP) September 2003 This report should be referenced as: McKee, L., Leatherbarrow, J., Newland, S., and Davis, J., 2003. A review of urban runoff processes in the Bay Area: Existing knowledge, conceptual models, and monitoring recommendations. A report prepared for the RMP Sources, Pathways and Loading Workgroup. San Francisco Estuary Regional Monitoring Program for Trace Substances. SFEI Contribution Number 66. San Francisco Estuary Institute, Oakland, Ca. ii ACKNOWLEDGMENTS The authors would like to thank the RMP Sources Pathways and Loadings Workgroup for developing the concepts the lead to the review of literature and available data pertaining to runoff of water, sediment and contaminants in the Bay Area urban and rural landscape. Active workgroup members have included: Andy Gunther, Andy Jahn, Dave Tucker, Don Yee, Dyan Whyte, Fred Hetzel, Jon Konnan, Jim Kuwabara, Jim McGrath, Khalil Abu-Saba, Neil Ganju, Richard Looker, Russ Flegal, Terry Cooke, Tom Hall, Tomas Mumley, and Trish Mulvey. We would specifically like to thank the following reviewers: Jan Null of Golden Gate Weather Services, Ray Wilson, Scott Wright, Joe Domagalski, and Jeff Steuer of the United States Geological Survey, Andy Jahn of the Port of Oakland, Andy Gunther of Applied Marine Sciences, Trish Mulvey of Clean South Bay, and Fred Hetzel and Mike Napolitano of the San Francisco Bay Regional Water Quality Control Board. The comments, both broad and general improved the quality of data and interpretations and readability of each chapter and helped to make the overall product more useful to a wide audience. We would like to thank Eric Wittner of SFEI for assistance with development of GIS maps and figures displaying spatial data within the document. We greatly acknowledge the assistance of Patricia Chambers and her colleagues at SFEI for final layout, production and web publishing iii TABLE OF CONTENTS Part 1: Introduction.............................................................................................................. 1 History............................................................................................................................. 2 Rationale.......................................................................................................................... 3 Objectives of this literature review ................................................................................. 5 Report structure............................................................................................................... 5 References ....................................................................................................................... 5 Part 2: Climate and hydrology ............................................................................................ 7 Introduction ..................................................................................................................... 8 Problem statement....................................................................................................... 8 Importance of runoff from local watersheds ............................................................... 8 Watershed characteristics................................................................................................ 9 Area ............................................................................................................................. 9 Land use and population ............................................................................................. 9 Temperature and climate........................................................................................... 12 Gauging history, seasonal and spatial distribution.................................................... 12 Dry versus wet periods.............................................................................................. 13 Rainfall as a driver for sediment transport................................................................ 17 Runoff............................................................................................................................ 18 Gauging history and variability................................................................................. 18 Response time ........................................................................................................... 23 Impacts of urbanization............................................................................................. 24 Storm runoff characteristics in the Bay Area ............................................................ 27 Water budget ................................................................................................................. 28 Rainfall input............................................................................................................. 29 Runoff........................................................................................................................ 29 Evapotranspiration, groundwater flow and soil moisture ......................................... 30 Summary ....................................................................................................................... 31 References ..................................................................................................................... 31 Part 3: Sediment processes................................................................................................ 34 Introduction ................................................................................................................... 35 Problem statement..................................................................................................... 35 Importance of runoff from local watersheds ............................................................. 35 General watershed sediment processes ..................................................................... 35 Sources of sediment ...................................................................................................... 36 Landslides.................................................................................................................. 36 Channel bed and bank erosion .................................................................................. 40 Sediment erosion from urban and agricultural areas................................................. 41 Pathways of sediment.................................................................................................... 43 Storage....................................................................................................................... 43 Delivery of sediment – averaging on decadal time scales ........................................ 45 Sediment loads .............................................................................................................. 47 Suspended sediment Concentrations......................................................................... 47 iv TABLE OF CONTENTS Suspended sediment grain size.................................................................................. 51 Suspended sediment transport................................................................................... 51 Summary ....................................................................................................................... 61 References ..................................................................................................................... 62 Part 4: Polychlorinated biphenyls (PCBs)......................................................................... 67 Introduction ................................................................................................................... 68 Problem statement..................................................................................................... 68 Importance of runoff from local watersheds ............................................................. 68 PCB properties and analytical limitations..................................................................... 69 Properties................................................................................................................... 69 Analytical limitations ................................................................................................ 70 Historic and current sources.......................................................................................... 71 PCB transport in tributaries........................................................................................... 73 PCB partitioning and concentrations in tributaries ................................................... 74 PCB loading in tributaries........................................................................................