Hydraulic hazard exposure of humans swept away in a whitewater river
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Despite many deaths annually worldwide due to floods, no strategy exists to mechanistically map hydraulic hazards people face when entrained in a river. Previous work determined water depth–velocity product thresholds for human instability from standing or walking positions. Because whitewater rivers attract diverse recreation that risks entraining people into hazardous flow, this study takes the next step by predicting the hazard pattern facing people swept away. The study site was the 12.2-km bedrock–alluvial upper South Yuba River in the Sierra Nevada Mountains. A novel algorithm was developed and applied to two-dimensional hydrodynamic model outputs to delineate three hydraulic hazard categories associated with conditions for which people may be unable to save themselves: emergent unsavable and steep emergent surfaces, submerged unsavable surfaces, and hydraulic jumps. Model results were used to quantify exposure of both an upright and supine entrained person to collision and body entrapment hazards. Hazard exposure was expressed with two metrics: passage proximity (how closely a body approached a hazard) and reaction time (time available to respond to and avoid a hazard). Hazard exposure maps were produced for multiple discharges, and the areal distributions of exposure were synthesized for the river segment. Analyses revealed that the maximum hazard exposure occurred at an intermediate discharge. Additionally, longitudinal profiles of the results indicated both discharge-dependent and discharge-independent hazards. Relative to the upright body, the supine body was overall exposed to less dangerous channel regions in passage down the river, but experienced more abrupt encounters with the danger that did occur.
KeywordsHydraulic hazards River rapids Floods Hydraulic jumps Whitewater
No external grant was provided directly for this work. Indirect support was received from the USDA National Institute of Food and Agriculture, Hatch Project Number #CA-D-LAW-7034-H. Precursor data were collected for different purposes with an award from the Instream Flow Assessment Program of the Public Interest Energy Research Program of the California Energy Commission. The Instream Flow Assessment Program was administered by the Center of Aquatic Biology and Aquaculture of the University of California, Davis. This project involved a large collaborative effort that was only possible by gracious contributions of effort and resources by many people, including relicensing stakeholders, their consultants, our paid project staff, and UC Davis student volunteers. Helpful reviews and feedback of the final technical report with the 2D model and other precursor study components leading up the work herein were provided by Professor Allen James (University of South Carolina), Dudley Reiser (R2 Resource Consultants, Inc), Michael Barclay (HDR/DTA), Thomas Studley (PG&E), and Dr. Joshua Wyrick (Lafayette College). Lastly, Daniel Brasuell provided assistance in locating the rapids present along the study segment.
- Belknap L (1998) Upgrading the American version of the International Scale of River Difficulty. American Whitewater. https://www.americanwhitewater.org/content/Wiki/safety:introratings?
- Bern C, Sniezek J, Mathbor GM, Siddiqi MS, Ronsmans C, Chowdhury AMR, Choudhury AE, Islam K, Bennish M, Noji E, Glass RI (1993) Risk factors for mortality in the Bangladesh Cyclone of 1991. Bull WHO 71:73–78Google Scholar
- Chanson H, Brown R, McIntosh D (2014) Human body stability in floodwaters: the 2011 flood in Brisbane CBD. In: 5th IAHR international symposium on hydraulic structures, The University of Queensland, pp 1–9Google Scholar
- Cox RJ, Yee M, Ball JE (2004) Safety of people in flooded streets and floodways. In: National conference on hydraulics in water engineering. Engineers AustraliaGoogle Scholar
- Cox RJ, Shand TD, Blacka MJ (2010) Australian Rainfall and Runoff revision project 10: appropriate safety criteria for people, Engineers AustraliaGoogle Scholar
- Dietrich WE, Bellugi D, Real de Asua R (2001) Validation of the shallow landslide model, SHALSTAB, for forest management. In: Wigmosta MS, Burges SJ (eds) Land use and watersheds: human influence on hydrology and geomorphology in urban and forest areas, Water science and application, vol 2. American Geophysical Union, Washington, pp 195–227Google Scholar
- Foster DN, Cox RJ (1973) Stability of children on roads used as floodways. University of New South Wales Water Research Laboratory technical report 73(13)Google Scholar
- Gard M (2003) Flow-habitat relationships for spring-run Chinook salmon spawning in Butte Creek. Energy Planning and Instream Flow Branch Butte Creek 2D Modeling final report, U.S. Fish and Wildlife ServiceGoogle Scholar
- Karvonen RA, Hepojoki A, Huhta HK, Louhio A (2000) The use of physical models in dam-break analysis. RESCDAM final report, Helsinki University of Technology, HelsinkiGoogle Scholar
- Keller RJ, Mitsch B (1993) Safety aspects of the design of roadways as floodways. Urban Water Research Association of Australia, BrisbaneGoogle Scholar
- Lai YG (2008) SRH-2D version 2: theory and user’s manual. U.S. Department of the Interior, Bureau of Reclamation, WashingtonGoogle Scholar
- Leopold LB (1969) The rapids and the pools—Grand Canyon. U.S. Geological Survey Professional Paper 669, pp 131–145Google Scholar
- Pasternack GB, Senter AE (2011) 21st century instream flow assessment framework for mountain streams. California Energy Commission, PIER, CEC‐500-2013-059Google Scholar
- Pasternack GB, Valle BL, Paige D, Shaw M (2006a) Portable apparatus and method for measuring hydraulic features in rivers and streams. United States Patent Office, Patent #7062962Google Scholar
- Renard KG, Foster GR, Yoder DC, McCool DK (1994) RUSLE revisited—status, questions, answers, and the future. J Soil Water Conserv 49:213–220Google Scholar
- Takahashi S, Endoh K, Muro ZI (1992) Experimental study on people’s safety against overtopping waves on breakwaters. Rep Port Harb Inst 34(4):4–31Google Scholar
- Webb RH, Pringle PT, Rink GR (1989) Debris flows from tributaries of the Colorado River, Grand Canyon National Park, Arizona. U.S. Geological Survey Professional Paper 87-118Google Scholar
- Western U.S. Historical Summaries by State, Annual Precipitation Averages and Extremes. Western Regional Climate Center. http://www.wrcc.dri.edu/htmlfiles/ca/ca.ppt.ext.html. Accessed 23 Oct 2010
- Wischmeier WH, Smith DD (1978) Predicting rainfall erosion losses: a guide to conservation planning. Agriculture handbook 537. United States Department of Agriculture, WashingtonGoogle Scholar