Contributions of human activities to suspended sediment yield during storm events from a small, steep, tropical watershed

Messina, A. M.; Biggs, Trent W.

doi:10.1016/j.jhydrol.2016.03.053

Cited by 32 publications

(15 citation statements)

References 57 publications

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“…Alluvial valleys have been carved over time from erosion and are spaced along the island coastline (Stearns, 1944;Izuka et al, 2007). The 2 km 2 Faga'alu watershed contains the Faga'alu Stream (3 km), with headwaters on the slopes of Matafao Mountain running down an alluvial valley, and emptying into the Faga'alu Bay of the outer Pago Harbor (Messina and Biggs, 2016). The undisturbed upper watershed is steeply sloped and forested, while the Faga'alu village lies on the lower alluvial plain.…”

Section: Figure 1 | (A)mentioning

confidence: 99%

“…The undisturbed upper watershed is steeply sloped and forested, while the Faga'alu village lies on the lower alluvial plain. The valley slopes are comprised of dense basaltic rocks, which also underlie the alluvial deposits of silty and sandy clay loams of >50 m thickness on the lower plain where human development is highest (Messina and Biggs, 2016). One groundwater well, managed by the American Samoa Power Authority (ASPA) is used as a municipal water source, and is located halfway up the developed area, near the boundary where the alluvium intersects the basalt (Figure 1B).…”

Section: Figure 1 | (A)mentioning

confidence: 99%

“…Groundwater discharge to streams and the coastal ocean is often hard to quantify and is the subject of this study, which focuses on the Faga'alu watershed on the island of Tutuila, American Samoa (Figure 1A). The benthic ecosystem in Faga'alu Bay is classified as one of the most impacted on the island (Houk et al, 2005;Tuitele et al, 2014) and it has been labeled a priority remediation watershed by the U.S. Coral Reef Task Force (Messina and Biggs, 2016).…”

Section: Introductionmentioning

confidence: 99%

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Submarine Groundwater Discharge and Stream Baseflow Sustain Pesticide and Nutrient Fluxes in Faga'alu Bay, American Samoa

Welch

Dulai

El‐Kadi

et al. 2019

Front. Environ. Sci.

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It is increasingly recognized that groundwater discharge in the form of stream baseflow and submarine groundwater discharge (SGD) plays an important role in contaminant transport. This study seeks to demonstrate the importance of groundwater flow for the distribution and transport of selected pesticides and nutrients in the Faga'alu aquifer on the island of Tutuila in American Samoa. Field measurements, including seepage runs and analysis of stream and groundwater for pesticides and nutrients, were combined with hydrological modeling. Selected analytes were glyphosate (GLY), dichlorodiphenyl-trichloroethane (DDT), imidacloprid, and azoxystrobin for pesticides and chemical species of nitrogen, phosphate, and silicate for nutrients. Hydrological flow and transport models of the aquifer were built to simulate groundwater flow and to provide estimates of GLY and dissolved inorganic nitrogen (DIN) fluxes. Stream baseflow was responsible for 59% and SGD for 41% of groundwater flow to the bay, which totaled 6,550 ± 980 m 3 /d in the dry season when surface runoff was negligible. DDT was found in 85% and GLY in 100% of tested samples. SGD and baseflow thus delivered 9 ± 2 g/d of DDT, 0.9 ± 0.2 g/d of GLY, 570 ± 100 g/d of DIN and 840 ± 110 g/d of dissolved inorganic phosphorus (DIP) into Faga'alu Bay. While all pesticide levels are below environmental limits, their presence in baseflow and SGD, which discharge continuously year-round, result in sustained fluxes of GLY and DDT to the reef. The presence of DDT in groundwater decades after its last application confirms its long-term environmental persistence.

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Section: Figure 1 | (A)mentioning

confidence: 99%

Section: Figure 1 | (A)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Submarine Groundwater Discharge and Stream Baseflow Sustain Pesticide and Nutrient Fluxes in Faga'alu Bay, American Samoa

Welch

Dulai

El‐Kadi

et al. 2019

Front. Environ. Sci.

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“…There are few studies (Walling & Fang, 2003;Messina & Biggs, 2016) where mining impact on SSC has been measured. Some of them were undertaken by establishing annual sediment loads for a whole catchment.…”

Section: The Baci Approachmentioning

confidence: 99%

“…In mined areas, baseline definition has been studied widely in association with hydro-chemical properties (Yanguo et al, 2002;Oyarzun et al, 2011). Only few publications exist as far as a sediment transport baseline is concerned (Pentz & Kostaschuk, 1999;Chalov, 2014;Messina & Biggs, 2016). One of these is that on the Ngarradj catchment (Australia), for which a baseline of several parameters including suspended sediment concentration (SSC) (Evans et al, 2004) and for bed-material grain size (Saynor et al, 2006) were defined.…”

Section: Introductionmentioning

confidence: 99%

Baseline to Evaluate Off‐Site Suspended Sediment‐Related Mining Effects in the Alto Tajo Natural Park, Spain

et al. 2016

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Mining is a human activity with considerable environmental impact. To evaluate such impacts, international laws require undertaking local studies based on direct sampling to establish baseline conditions of parameters modified by human activities. Mining takes place near the Alto Tajo Natural Park, where a suspended sediment concentration (SSC) baseline is required to determine whether mining affects water quality. To this end, we have monitored the Tajo River and its tributary the Tajuelo following Before–After Control‐Impact (BACI) techniques, recommended by Australian and New Zealand laws, requiring a specific method based on continuous monitoring and sampling to enable evaluation of SSCs. An SSC baseline has been defined at stations situated upstream of the mining area and compared with those downstream. The highest detected SSC upstream of the Tajuelo mines was 24 g l−1 whereas the highest simultaneous downstream value was 391 g l−1, more than one order of magnitude higher than the supposed baseline (24 g l−1). Additionally, this value is 1000 times more than the average concentration of 25 mg l−1, used by the European Union until 2015, to guarantee the quality of salmonid waters. Following a BACI approach, a statistically significant SSC impact has been identified. The mined areas are the only source that can explain this increase. This is the first instance that such an increase and baseline have been found using this method. BACI is a simple and reliable method recommended for studying degraded areas rather than an irrelevant, fixed standard as included in most international laws. Copyright © 2016 John Wiley & Sons, Ltd.

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Seasonal fluxes and sediment routing in tropical catchments affected by nickel mining

Domingo

Attal

Mudd

et al. 2021

Earth Surf Processes Landf

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Contributions of human activities to suspended sediment yield during storm events from a small, steep, tropical watershed

Cited by 32 publications

References 57 publications

Submarine Groundwater Discharge and Stream Baseflow Sustain Pesticide and Nutrient Fluxes in Faga'alu Bay, American Samoa

Submarine Groundwater Discharge and Stream Baseflow Sustain Pesticide and Nutrient Fluxes in Faga'alu Bay, American Samoa

Baseline to Evaluate Off‐Site Suspended Sediment‐Related Mining Effects in the Alto Tajo Natural Park, Spain

Seasonal fluxes and sediment routing in tropical catchments affected by nickel mining

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