Particle Size Analysis of Two Adjacent Watersheds  By Jessica Kashian  Mentor: Tobias Finke

Background Information  Increase in Urbanization in the Southwest  Stress on Watersheds by decrease infiltration rates causing increased surface runoff which can lead to flooding and costly water infrastructure for prevention  Studying this phenomenon allows us to quantify effects of urbanization on infiltration rates  This would enable city planners to make more informed decisions on flood prevention strategies in new housing developments

Study Area: Ft Huachuca and Sierra Vista, AZ

Objectives  Analyze Soil Samples for Particle Size Distribution  Statistical Analysis to determine whether there are differences between two watersheds  Investigate the relation between Particle Size Distribution and Infiltration  Research Questions:  Are the particle size distributions different between the watersheds?  Can differences in infiltration capacities be explained by particle size distribution of the soil?

Methods  20 Soil Samples Collected from each Watershed  Eliminate Carbonates by pretreatment of the Soil Samples

Methods 50 grams of each treated Sample is used in Hydrometer Readings Hydrometer: measures density of soil solution Measurements were converted to sand, silt and clay fractions

Results and Discussion Are the particle size distributions different between watersheds? Sand SiltClay Statistical Comparison of Particle Fractions for Both Watersheds t-Test DFProb > (t) <.0001 t-Test DFProb > (t) t-Test DFProb > (t) <.0001 FH LT

Results and Discussion Can differences in infiltration capacities be explained by particle size distribution of the soil? Y= 0 +1X R 2 = 0.35

Conclusions  Higher percentages of clay in developed area  Lower percentages of sand in the developed area  35% of the Infiltration values could be explained by particle sizes

Acknowledgements and Special Thanks  Susan Moran  Rae-Landa Gomez-Pond  Chandra Holifield Collins  Jeff Kennedy  Kevin Loeffelmann  William Emmerich