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Las Vegas, NV, United States

Adhikari A.R.,55 E. Flamingo Rd. | Gautam M.R.,55 E. Flamingo Rd. | Acharya K.,55 E. Flamingo Rd.
Urban Water Journal | Year: 2013

The distribution of bacterial contaminants (Escherichia coli and total coliforms) and nutrients (nitrogen and phosphorus) in a rapidly growing metropolitan area, the Las Vegas Valley, were studied to assess the contributions of point and nonpoint pollution sources under dry weather flow (pre rainfall) and wet weather flow (post rainfall) events. Nonpoint sources emanating from urban centers and septic seepage were found to be a primary source of bacterial contamination in the Las Vegas Wash, a mainstream wash channel where the Las Vegas Valley watershed drains. Contribution of point sources (wastewater treatment plants) to E. coli and total coliforms were found to be negligible. However, data in the Tropicana/Flamingo Wash, a tributary of the Las Vegas Wash, showed high bacterial activities in the wet antecedent rainfall condition as compared to the pre-rain dry antecedent condition suggesting that the rainfall increased bacterial activities. © 2013 Copyright Taylor and Francis Group, LLC. Source

Adhikari A.R.,55 E. Flamingo Rd. | Adhikari A.R.,University of Nevada, Las Vegas | Gautam M.R.,55 E. Flamingo Rd. | Yu Z.,University of Nevada, Las Vegas | And 2 more authors.
Ecological Engineering | Year: 2013

Quantifying mechanical properties of native vegetation for streambank stability is a critical need of the Lower Colorado riparian revegetation effort. In the present study we estimated root cohesion for four representative native desert shrub species: Artiplex lentiformis (Torr.) S. Watson, Lycium andersonii A. Gray, Larrea tridentata (DC.) Coville, and Allenrolfea occidentalis (S. Watson) Kuntze to understand their suitability in streambank stabilization in the framework of a revegetation campaign. Field experiments were conducted to measure root length, root length density, root area ratio, and root tensile strength. Finally, the root cohesion values were assessed using a simple perpendicular model. Root area ratio estimates showed that on average plant roots occupy 0.46% of the area under the crown of the selected species. The root tensile strength (Tr) was greatest for L. tridentata (62.23MPa) followed by L. andersonii (53.53MPa), A. lentiformis (49.17MPa), and A. occidentalis (35.03MPa). The root cohesion values could be used to rank the species according to their potential for shallow bank slope stabilization in riparian ecosystems of a desert environment. The maximum root cohesion in the present study was estimated for A. lentiformis (97.6kPa) followed by L. andersonii (89.3kPa), L. tridentata (35.6kPa), and A. occidentalis (34.8kPa). Root cohesion values were also estimated using Fiber bundle model (FBM) and compared to the perpendicular root model of Wu et al. (1979). The comparative root cohesion values for root diameter (>0.5mm) suggest that Wu's model estimates are greater than those of the FBM by a reduction factor ranges between 0.35 and 0.56 for our studied species. © 2012 Elsevier B.V. Source

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