Spatial and Temporal Patterns of Nutrient Loading Along a Mix of Restored and Unrestored Stream Sites in Charlottesville, VA and Baltimore, MD

Abstract:

Nutrient enrichment in water bodies causes algal blooms, oxygen depletion, mortality of aquatic organisms and water pollution. Urban watersheds are significant nutrient sources to streams, with a complex mix of fertilizers, animal waste, sanitary sewage leaks, and erosion derived nitrogen and phosphorus loading varying by season and flow conditions. Understanding the potential sources of nitrogen and phosphorus is a key to designing mitigation approaches. The purpose of this research is to investigate spatial and temporal patterns of nutrient loading, and the effectiveness of stream restoration in urban streams. Restoration aims to reduce nutrients entering streams as well as to enhance microbial processes such as denitrification. Field sites include streams of varied forested and impervious covers as well as restoration history in Charlottesville, Virginia, and Baltimore, Maryland.

We use weekly synoptic surface water discharge and chemistry along a mix of restored and unrestored sites, with dissolved oxygen, conductivity, temperature, and photosynthetically active radiation to estimate metabolism. The diversity of sites in this project, including a constructed wetland and stormwater pond provides both depth and breadth of data to assess spatial and temporal patterns of nutrient sources and stream processing. Simulated results from an i-Tree Hydro model will be used to analyze land cover influences on volume and quality of runoff. Additional simulations of hydrologic processes such as soil infiltration and direct runoff will be obtained through a HEC-HMS model. The hope is that the diverse approach to this research will add to the existing scientific knowledge about stream restoration.