Abstract

Waimea Canyon is a deep V-shaped canyon on the island of Kauai, Hawaii in which the Waimea River and its tributaries flow. The shape and size of the canyon are noteworthy and unusual compared to its contemporary canyons on the Hawaiian Islands which are usually U-shaped or flat bottomed. This could be because there is significantly more physical erosion in Waimea Canyon compared to others. A water budget was created using ArcGIS Pro and data from the University of Hawaii’s rainfall and evapotranspiration atlases, as well as from the United States Geological Survey’s stream gage data. A mass flux was estimated using ArcGIS pro by creating a paleosurface from the ridge points and then finding the mass difference between todays watershed and the watershed with the paleosurface. Weathering reactions were made to model the processes in the watershed. The reactants were found from using oxide percentages of Kauai basalts and inputting them into MELTs to estimate mineralogy. The products were found by analysis of soil and water samples in the area of the Canyon. In the Waimea River watershed approximately 159 t/km2 /yr is removed, of which 56% is by physical erosion. This was compared to the V-shaped Makaweli river watershed where approximately 12% is removed by physical erosion and in the U-shaped Hanalei watershed ≈ 68% is removed. While these differences could be explained by vegetation cover, precipitation, and slope steepness it shows that there is not more physical erosion in Waimea Canyon compared to the others. Thus, the origin of the V-shape of Waimea Canyon remains unexplained.

Degree

College and Department

Physical and Mathematical Sciences; Geological Sciences

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