american samoa - University of Hawaii at Manoa Botany Department

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Immediately downstream of these two parallel stream channels, a single main stem wasestablished. However, the stream alteration in this area significantly eroded lands along the eastbank of the stream. Informal discussions with the adjoining landowner, George Galeai, as wellas uprooted ifi, coconut, and other trees provided ample evidence of the consequencesassociated with the upstream modification.Stream FlowsHistorical Stream FlowsIn 1996, the U.S. Geological Survey (USGS) published an estimated median stream flow forPapa Stream (Table 7-1). The median stream flow estimate was based upon historical streamflow measurements obtained from a continuous-record gage (No. 16944200) that was situated500 feet downstream of Papa/Tauese Stream confluence between 1966 and 1976. The samegage was occasionally operated as a partial-record site between 1968 and 1983. The highestflow recorded at this stream gage was 1,640 cubic feet per second (cfs) on April 29, 1975.However, USGS reported that stream flows were absent from this stream location for manydays of the year.A low-flow, partial record station (No. 16944000), which was located 0.3 mile upstream of thePapa/Tauese Stream confluence, provided 30 stream measurements between 1959 and 1990.The U.S. Geological Survey estimated a median stream flow of 1.48 cfs at this station location(Wong, 1996).TABLE 7-1MEDIAN STREAM FLOW ESTIMATEPAPA STREAMStream USGSGageStationGage LocationPapa Stream 169442000 500 feet downstream fromPapa/Tauese StreamconfluencePapa Stream 16944000 0.3 mile upstream of Papa/Tauese Stream confluenceSource: Wong, 1996Stream FlowMeasurements(number)Continuousintermittentlybetween 1966-1976Estimated MedianFlow (cfs)1.3030 1.48American Samoa Wetland/Stream Restoration and Enhancement PlanFebruary 2001, Papa Stream, Page 7-5
Stormwater Discharges and Related Flood PotentialIn 1999, Pedersen Planning Consultants recently made a hydrologic analysis of potentialstormwater discharges into Pala Lagoon that could be generated from a range of storm events(Pedersen Planning Consultants, 2000). Through hydrologic modeling, PPC determined thatpotential stormwater discharges into the Pala Lagoon can range from 739 cubic feet per second(cfs) for a 2-year storm and about 2,072 cfs for a 100-year storm. Consequently, significantstream flows can be carried by Papa Stream for more common 2-year events, as well as lessfrequent 100-year storms.TABLE 7-2STORMWATER DISCHARGES FROM PAPA STREAM INTO PALA LAGOON2,10,50, AND 100-YEAR STORM EVENTSIN CUBIC FEET PER SECOND (CFS)Location 2-Year Storm 10-Year Storm 50-Year Storm 100-Year StormPapa Stream 739 1,134 1,847 2,072Source: Pedersen Planning Consultants, 2000In November 1999, PPC also gathered cross-sectional data along the 1,200-foot Papa Streamsegment to assess the capability of this stream segment to accommodate these stormwaterevents. Cross sections were recorded at 100-foot intervals along this stream segment.With the application of hydrologic modeling, PPC determined that potential stormwater flowsare much larger than the capacity of the stream at each cross-section (Table 7-3). Oneimportant exception is the bridge culverts underneath Route 1 (station 1+00), which canaccommodate stormwater flows of about 2,162 cfs. Consequently, the culverts underneathRoute 1 can support potential flows from a 100-year storm event.TABLE 7-3CROSS-SECTIONAL ANALYSISALONG PAPA STREAM SEGEMENTMaximum Stream FlowStationSlope of Stream(percent)Through Cross Section(cfs)1+00 1.0 2,1622+00 1.0 3803+00 1.4 4204+00 1.5 6075+00 2.0 3446+00 1.2 1537+00 1.1 2228+00 1.2 3219+00 1.9 62910+00 1.6 51311+00 1.5 33211+80 1.3 292Source: Pedersen Planning Consultants, 2000American Samoa Wetland/Stream Restoration and Enhancement PlanFebruary 2001, Papa Stream, Page 7-6
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Asili StreamAMERICAN SAMOAWETLAND/S
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American SamoaWetland/Stream Restor
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American Samoa Wetland/Stream Resto
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Figure 1-1Location of Potential Wet
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Onsite InvestigationsNovember 1999G
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Where appropriate, stream cross sec
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Chapter TwoTULA WETLANDLOCATIONTula
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Figure 2-2Tula WetlandExisting Cond
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Improved channelization of stormwat
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LAND USES IN THE VICINITY OF TULA W
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Figure 2-3Option 2: Detention of St
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Figure 2-4Option 3: Expansion of Ta
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Comparative Benefits and ImpactsPPC
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TABLE 2-4PRELIMINARY COST ESTIMATEP
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TABLE 2-5LONG-TERM RESOURCE MONITOR
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TABLE 2-6 (CONTINUED)FIELD MONITORI
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Chapter ThreeALAO WETLANDLOCATIONAl
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Figure 3-2Taufusi MarchExisting Con
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Figure 3-3FEMA 100-Year Flood Plain
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East Portion of the MarshThe impact
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WETLAND RESTORATION AND ENHANCEMENT
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The availability of new, blight-res
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Long-Term Monitoring and Site Maint
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TABLE 3-7FIELD MONITORING WORKSHEET
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Recommended monitoring stations or
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Figure 4-1Location MapAoa Village W
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No stream flow estimates are availa
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Fresh-Water SwampThe fresh-water sw
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ecome dominant if there is a nearby
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Relative Abundance and Diversity of
Page 65 and 66: Option 4: Restore Mangrove Forest U
Page 67 and 68: TABLE 4-5COMPARATIVE EVALUATIONWETL
Page 69 and 70: Long-term resource management activ
Page 71 and 72: TABLE 4-9FIELD MONITORING WORKSHEET
Page 73 and 74: • begin at the Tapua Stream mouth
Page 75 and 76: Figure 5-1Location MapSoutheast Wet
Page 77 and 78: Tufu Stream and two stream branches
Page 79 and 80: Mr. Whistler was part of a three-pe
Page 81 and 82: InvertebratesCrustacean densities w
Page 83 and 84: FIGURE 5-3OPTION 1: RESTORE RIPARIA
Page 85 and 86: TABLE 5-4COMPARATIVE EVALUATIONWETL
Page 87 and 88: Long term monitoring of the Vatia w
Page 91 and 92: More specific monitoring of stream
Page 93 and 94: Figure 6-1Location MapVaipito Strea
Page 95 and 96: Stream FlowsHistorical Stream Flows
Page 97 and 98: California grass (Brachiaria mutica
Page 99 and 100: FIGURE 6-3FISH AND INVERTEBRATE SUR
Page 101 and 102: Most of lower Vaipito Stream segmen
Page 103 and 104: Red mangrove should be planted with
Page 105 and 106: TABLE 6-7PRELIMINARY COST ESTIMATEC
Page 107 and 108: TABLE 6-9LONG-TERM RESOURCE MONITOR
Page 109 and 110: TABLE 6-10 (Continued)FIELD MONITOR
Page 111 and 112: Vehicular and pedestrian access to
Page 113 and 114: Figure 7-1Location MapLeele-Papa-Ta
Page 115: Stream flow, in some cases, is cons
Page 119 and 120: AQUATIC FISH AND INVERTEBRATESGener
Page 121 and 122: Opportunities and StrategiesOption
Page 123 and 124: Figure 7-3Option 2: Reduction of Er
Page 125 and 126: TABLE 7-8PRELIMINARY COST ESTIMATEP
Page 129 and 130: TABLE 7-10 (Continued)FIELD MONITOR
Page 131 and 132: More specific monitoring of stream
Page 133 and 134: Figure 8-1Location MapSauino Stream
Page 135 and 136: Stream FlowsHistorical Stream Flows
Page 137 and 138: AQUATIC FISH AND INVERTEBRATESGener
Page 139 and 140: Figure 8-3Option 1: Construction of
Page 141 and 142: FIGURE 8-5OPTION 2: PLANT NATIVE RI
Page 143 and 144: Long-Term Monitoring and Site Maint
Page 147 and 148: TABLE 8-8 (Continued)FIELD MONITORI
Page 149 and 150: LOCATIONChapter NineLEAFU STREAMLea
Page 151 and 152: Figure 9-2Leone Pala and 300-Foot L
Page 153 and 154: However, during and following heavi
Page 155 and 156: Vegetation TrendsThe lower Leafu St
Page 157 and 158: LAND USES ADJACENT TOLOWER LEAFU ST
Page 159 and 160: Option 2: Construct Basaltic Wall,
Page 161 and 162: Figure 9-5:Stabilize East Stream Ba
Page 163 and 164: TABLE 9-7PRELIMINARY COST ESTIMATEP
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TABLE 9-9 (Continued)FIELD MONITORI
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Chapter TenASILI STREAMLOCATIONAsil
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Figure 10-2Asili Stream SegmentExis
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Stormwater Discharges and Related F
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Further downstream, the stream chan
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TABLE 10-4SUMMARY OF MACROFAUNAL OR
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American Samoa Wetlands/Streams Res
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CLEAN-UP OF LOWER ASILI STREAMLABOR
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TABLE 10-9LONG-TERM RESOURCE MONITO
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TABLE 10-10 (Continued)FIELD MONITO
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Vehicular and pedestrian access to
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Figure 11-1Location MapFusi Wetland
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WETLAND VEGETATIONNovember 1999 Sur
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The lack of stream flow entering th
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Figure 11-3Option 1: Remove Solid W
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Recommended Option and Estimated Pr
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TABLE 11-6FIELD MONITORING WORKSHEE
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Any future monitoring stations or s
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Project ManagerRepresentatives of a
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REFERENCESBiosystems Analysis, Inc.
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APPENDIX ASUMMARY OFPLANTSOBSERVED
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Species Family EnglishNameSamoanNam
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APPENDIX CSUMMARY OFAQUATIC MACROFA
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