Stream Characteristics of Arroyo Zarco
Document Type
Oral Presentation
Campus where you would like to present
SURC Ballroom C/D
Start Date
15-5-2014
End Date
15-5-2014
Keywords
Gradient, Debris Flows, Sediment
Abstract
We investigated the influence of external factors on sediment size and stream gradient in an ephemeral stream channel, the Arroyo Zarco at Chamela, Jalisco, Mexico (19˚30′N, 105˚3′W). The external factors that we examined were tributary streams, woody debris, and debris flows. We hypothesized that these factors would cause a reduction in the stream gradient, and an increase in sediment size. We surveyed the longitudinal gradient of a 600-m reach of the Arroyo Zarco, surveyed channel cross-sections at noticeable transitions between sediment sizes, and measured average sediment size at each cross section. We calculated the average surface sediment size at each cross-sectional area using a step-randomization method. To determine change in stream gradient, we measured the change in elevation every 10 meters along the channel using a surveyor’s tape measure and leveling scope. Qualitative observations of sediment size, presence/absence of the listed external factors, and presence of bedrock were noted every 10 meters along the stream channel. The locations of all sites were documented with a Geographic Positional System (GPS) instrument for subsequent mapping of the channel changes. The sediment size was larger downstream of debris flows and tributary streams, as we predicted. In contrast, sediment size was smaller downstream of accumulations of large woody debris. A change in gradient was correlated with tributaries, debris flows, and woody debris, but not all change in gradient was due to these external influences. The results, therefore, partially support our hypothesis.
This presentation received a College of the Sciences Best Poster Presentation Award for 2014.
Recommended Citation
Duffy, Jared; Rush, Philip; and Terrile, Kenny, "Stream Characteristics of Arroyo Zarco" (2014). Symposium Of University Research and Creative Expression (SOURCE). 20.
https://digitalcommons.cwu.edu/source/2014/posters/20
Poster Number
37
Additional Mentoring Department
Biology
Stream Characteristics of Arroyo Zarco
SURC Ballroom C/D
We investigated the influence of external factors on sediment size and stream gradient in an ephemeral stream channel, the Arroyo Zarco at Chamela, Jalisco, Mexico (19˚30′N, 105˚3′W). The external factors that we examined were tributary streams, woody debris, and debris flows. We hypothesized that these factors would cause a reduction in the stream gradient, and an increase in sediment size. We surveyed the longitudinal gradient of a 600-m reach of the Arroyo Zarco, surveyed channel cross-sections at noticeable transitions between sediment sizes, and measured average sediment size at each cross section. We calculated the average surface sediment size at each cross-sectional area using a step-randomization method. To determine change in stream gradient, we measured the change in elevation every 10 meters along the channel using a surveyor’s tape measure and leveling scope. Qualitative observations of sediment size, presence/absence of the listed external factors, and presence of bedrock were noted every 10 meters along the stream channel. The locations of all sites were documented with a Geographic Positional System (GPS) instrument for subsequent mapping of the channel changes. The sediment size was larger downstream of debris flows and tributary streams, as we predicted. In contrast, sediment size was smaller downstream of accumulations of large woody debris. A change in gradient was correlated with tributaries, debris flows, and woody debris, but not all change in gradient was due to these external influences. The results, therefore, partially support our hypothesis.
This presentation received a College of the Sciences Best Poster Presentation Award for 2014.
Faculty Mentor(s)
Ely, Lisa; Beck, Daniel