Flood-frequency estimates for streams on Kauai, Oahu, Molokai, Maui, and Hawaii, State of Hawaii

Oki, Delwyn S.; Rosa, Sarah N.; Yeung, Chiu W.

doi:10.3133/sir20105035

Cited by 5 publications

(3 citation statements)

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“…Inconsistent trends in peak flow were also found by Oki et al . (). This lack of upward trends in high and peak streamflows is consistent with downward trends in extreme rainfall during the past half century (Chu et al ., ; Timm et al ., ).…”

Section: Discussionmentioning

confidence: 99%

Trends and shifts in streamflow in Hawai‘i, 1913–2008

Bassiouni

Oki

2012

Hydrological Processes

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This study addresses a need to document changes in streamflow and base flow (groundwater discharge to streams) in Hawai‘i during the past century. Statistically significant long‐term (1913–2008) downward trends were detected (using the nonparametric Mann–Kendall test) in low‐streamflow and base‐flow records. These long‐term downward trends are likely related to a statistically significant downward shift around 1943 detected (using the nonparametric Pettitt test) in index records of streamflow and base flow. The downward shift corresponds to a decrease of 22% in median streamflow and a decrease of 23% in median base flow between the periods 1913–1943 and 1943–2008. The shift coincides with other local and regional factors, including a change from a positive to a negative phase in the Pacific Decadal Oscillation, shifts in the direction of the trade winds over Hawai‘i, and a reforestation programme. The detected shift and long‐term trends reflect region‐wide changes in climatic and land‐cover factors. A weak pattern of downward trends in base flows during the period 1943–2008 may indicate a continued decrease in base flows after the 1943 shift. Downward trends were detected more commonly in base‐flow records than in high‐streamflow, peak‐flow, and rainfall records. The decrease in base flow is likely related to a decrease in groundwater storage and recharge and therefore is a valuable indicator of decreasing water availability and watershed vulnerability to hydrologic changes. Whether the downward trends will continue is largely uncertain given the uncertainty in climate‐change projections and watershed responses to changes. Copyright © 2012 John Wiley & Sons, Ltd.

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Section: Discussionmentioning

confidence: 99%

Trends and shifts in streamflow in Hawai‘i, 1913–2008

Bassiouni

Oki

2012

Hydrological Processes

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“…Grey solid curve shows best fit line from multiple change point Bayesian regression with dashed vertical lines indicating location of change points centred at ~2 and 400 km 2 , respectively. Circles show the maximum observed peak annual discharge for natural stream gages in Hawaiʻi (same gages used in local flood regression from Oki et al, 2010) coloured by mean annual precipitation, peak discharges near or on the flood envelope curve are outlined in red. [Colour figure can be viewed at wileyonlinelibrary.com]…”

Section: Resultsmentioning

confidence: 99%

“…Indeed, two flood events from Kauaʻi and East Molokaʻi have previously (Herschy, 2002) helped set the maximum global flood envelope. We use maximum observed floods on Hawaiʻi (gauges were selected from regional frequency flood analysis used by Oki et al, 2010) to evaluate the suitability of using a global maximum flood envelope curve in our analysis.…”

Section: Methodsmentioning

confidence: 99%

Limits to knickzone retreat and bedrock river incision on the Hawaiian islands

Raming,

Whipple,

Strauch

2024

Earth Surf Processes Landf

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A knickzone is defined as a waterfall or an oversteepened fluvial reach encompassing a series of waterfalls. Knickzones are remarkable landforms in that they may represent diametrically opposed conditions: either rapid upstream propagation of base‐level fall or a condition of stability and stalled response to base‐level fall. Knickzones on the Hawaiian islands exhibit evidence of both behaviours, and in this study, we explore whether this dichotomy can be explained by a threshold stream power for river incision. Topographic analysis shows that the transition between fluvial hanging valleys, where no measurable upstream retreat from the stream junction or coastline has occurred, and knickzones that have retreated or formed upstream of their outlet can be defined by a range of catchment sizes from ~0.5 to 6 km2. This transition is present on all volcanoes in our analysis regardless of significant base‐level fall, and there is no clear trend of drainage area above knickzones with volcano age. To explain these observations, we hypothesize that knickzones form or stabilize where maximum unit stream power () does not exceed the critical unit stream power required to incise bedrock . Using estimates of a maximum possible flood discharge as a function of drainage area to calculate , we show that drainage areas above knickzones are well described by the theoretical prediction that incision stalls when , where falls in a narrow range from 14 to 40 kW/m2. Furthermore, we demonstrate that knickzone positions are largely insensitive to mean climate conditions, likely reflecting the fact that extreme flood events are either insensitive or inversely correlated with mean annual rainfall.

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Synthetic Flows for Engineered Systems with Nonstationary Parameters: Study of Maui’s Wailoa Ditch

Grubert

Webber

2017

J. Hydrol. Eng.

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Flood-frequency estimates for streams on Kauai, Oahu, Molokai, Maui, and Hawaii, State of Hawaii

Cited by 5 publications

References 0 publications

Trends and shifts in streamflow in Hawai‘i, 1913–2008

Trends and shifts in streamflow in Hawai‘i, 1913–2008

Limits to knickzone retreat and bedrock river incision on the Hawaiian islands

Synthetic Flows for Engineered Systems with Nonstationary Parameters: Study of Maui’s Wailoa Ditch

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