12.07.2015 Views

american samoa - University of Hawaii at Manoa Botany Department

american samoa - University of Hawaii at Manoa Botany Department

american samoa - University of Hawaii at Manoa Botany Department

SHOW MORE
SHOW LESS
  • No tags were found...

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Stream FlowsHistorical Stream FlowsIn 1996, the U.S. Geological Survey (USGS) published an estim<strong>at</strong>ed median stream flow <strong>of</strong>0.25 cubic feet per second (cfs) for Sauino Stream (Table 8-1). The median stream flowestim<strong>at</strong>e was based upon historical stream flow measurements obtained from 17 intermittentstream flow measurements taken from a low-flow, partial-record st<strong>at</strong>ion (No. 16942000)between 1959 and 1975. This st<strong>at</strong>ion was situ<strong>at</strong>ed approxim<strong>at</strong>ely 0.6 mile upstream from theSauino Stream mouth (Wong, 1996).TABLE 8-1MEDIAN STREAM FLOW ESTIMATESAUINO STREAMStream USGSGageSt<strong>at</strong>ionGage Loc<strong>at</strong>ionSauino Stream 16942000 0.6 mile upstream <strong>of</strong>Sauino Stream mouthSource: Wong, 1996Stream FlowMeasurements(number)Continuous intermittentlybetween 1959-1975Estim<strong>at</strong>edMedian Flow(cfs)0.25Stormw<strong>at</strong>er Discharges and Rel<strong>at</strong>ed Flood PotentialIn 1999, Pedersen Planning Consultants made a hydrologic analysis <strong>of</strong> potential stormw<strong>at</strong>erdischarges into Pala Lagoon th<strong>at</strong> could be gener<strong>at</strong>ed from a range <strong>of</strong> storm events (PedersenPlanning Consultants, 2000). Through hydrologic modeling, PPC determined th<strong>at</strong> potentialstormw<strong>at</strong>er discharges into the Pala Lagoon can range from 278 cubic feet per second (cfs) fora 2-year storm and about 777 cfs for a 100-year storm (Table 8-2).TABLE 8-2STORMWATER DISCHARGES FROM SAUINO STREAM INTO PALA LAGOON2,10,50, AND 100-YEAR STORM EVENTSIN CUBIC FEET PER SECOND (CFS)Loc<strong>at</strong>ion 2-Year Storm 10-Year Storm 50-Year Storm 100-Year StormSauino Stream 278 427 693 777Source: Pedersen Planning Consultants, 2000In November 1999, PPC also g<strong>at</strong>hered cross-sectional d<strong>at</strong>a along the 600-foot Sauino Streamsegment to assess the capability <strong>of</strong> this stream segment to accommod<strong>at</strong>e these stormw<strong>at</strong>erevents. Cross sections were recorded <strong>at</strong> 100-foot intervals along this stream segment.With the applic<strong>at</strong>ion <strong>of</strong> hydrologic modeling, PPC determined th<strong>at</strong> the maximum flow capacity<strong>of</strong> Sauino Stream is 279 cubic feet per second (cfs). When compared with potential stormw<strong>at</strong>erdischarges for a 2, 10, 50, and 100-year storm events, it is clear th<strong>at</strong> stormw<strong>at</strong>er flows gre<strong>at</strong>erthan a 2-year storm would exceed the capacity <strong>of</strong> Sauino Stream.The potential flood plain, associ<strong>at</strong>ed with a 100-year storm event in Nuuuli, was mapped by theFederal Emergency Management Agency (FEMA) in May 1991. Available flood insurancer<strong>at</strong>e maps prepared by FEMA suggest th<strong>at</strong> residential properties along the north and southbanks <strong>of</strong> the 600-foot Sauino Stream segment could be flooded from a 100-year storm event.American Samoa Wetlands/Streams Restor<strong>at</strong>ion and Enhancement PlanFebruary 2001, Sauino Stream, Page 8-4

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!