Landscape Impact on Suburban Runoff: Determining Phosphorus Loading Rates Based on Land Use.
Easton, Zachary

Phosphorus found in surface waters can cause problems for humans relying on clean drinking water and organisms needing unimpaired habitat. Little is know about the impact of developed areas on water quality. Suburban areas continue to grow in the Northeast United States, making their role in water quality protection of the utmost importance. A watershed in Ithaca, NY was selected, which is 47% developed and 332 ha in area. Runoff collected from 77 precipitation events from three landscapes was analyzed for dissolved reactive P (DRP) and mass losses calculated. Monitored landscapes included high (fertilized) and low (unfertilized) maintenance home lawns, and forested areas. Stream gauges were installed to monitor the impact of the landscapes on surface water quality. Analysis has shown that the most important factor to consider when assessing water quality is location, as areas closer to the watershed outlet had an order of magnitude more runoff than areas higher in the watershed. This affect can be attributed to higher soil moisture levels as a result of upslope contributing area in and greater area of impervious surface lower in the watershed. Controlling for location, unfertilized lawns had the highest runoff losses, followed by forested areas, and fertilized lawns the lowest. Fertilized landscapes had the highest DRP concentrations in runoff, but DRP mass losses were not significantly different between landscapes over the study period. However, there were seasonal differences, more DRP was lost from the fertilized areas in the spring and fall, whereas the forest and unfertilized areas had higher DRP losses in the summer.

Keywords: Phosphorus runoff, Landuse, Soil Moisture, Impervious surfaces,

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