A Sort-of Summary

Since my research this summer is part of my senior thesis, this blog post is not a summary of my entire project, just my progress to date.  Over the course of my time on campus over the summer, I have spent time both out in the field and back in the lab to gain a greater understanding of how retention ponds mitigate the negative effects of urbanization.  The overall goal of my research is to evaluate the effectiveness of the retention pond located off Route 199 (near the College Woods) at mitigating the effects of urbanization with respect to sediment transport. Although my research is still ongoing, I think I have made progress towards this goal.

With help from my advisor, this summer I was able to install a gauging station at the retention pond and place monitoring instruments in the stream downstream of the pond and in a reference stream (which drains a non-urbanized watershed).  From these instruments, I have been able to collect, compile, and (begin to) analyze data concerning the pond’s and the streams’ conductivity and temperature (and the area’s rainfall) over time. The retention pond typically has a conductivity of approximately 170 microsiemens per centimeter.  Water temperature in the pond displays diurnal fluctuations on the order of 4-5℃. Over the course of the study period, the water temperature exhibited a longer-term warming trend from April to July; the average temperature increased by 10℃ over this three month period. Water depth in the pond ranged from 0 meters to 0,65 meters.  In Strawberry Creek, conductivity values ranged from 150-300 microsiemens per centimeter and the water temperature ranged from 20-36℃. In Pogonia Creek, I had some issues with my conductivity probe, so I have not yet collected representative data. I predict that the conductivity in this stream will be much lower and much more stable over time compared Strawberry Creek; I think this will be the case since Pogonia Creek is predominately fed by groundwater.  Water temperatures in Pogonia Creek were between 17-20℃, much lower and much less variable than those of Strawberry Creek.

I have been able to determine a few relationships between the variables I have measured.  The most prominent of these is the inverse relationship between conductivity and water depth in the retention pond.  There are periods of time when depth increases and conductivity decreases, as well as times when depth decreases and conductivity increases.  As depth increases, conductivity could be reduced by runoff bringing in water with a lower conductivity than the conductivity of the water already in the pond.  Runoff could still bring contaminants into the pond, but overall dilution could occur. On the other hand, evaporation of water, leaving behind contaminants, explains how conductivity could increase as water depth decreases.  This relationship is clearly evident in some portions of the data, however some periods of time do not display this trend. I plan to continue this research during the school year and hope to find more relationships between variables in the data I will continue to collect.

Though I have made progress toward understanding and evaluating how effective this retention pond is at achieving its design goals, I still have a lot more research to do.  I am looking forward to continuing this project during the school year!

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