The State of the Severn River June, 2015 Andrew C. Muller, PhD. Associate Professor Oceanography Department United States Naval Academy

Introduction In order to understand the current state of the Severn River and where it may be headed in the near future, we must understand the physical processes that govern the river and past conditions

Tides in the Chesapeake Bay Chesapeake Bay is a partially mixed estuary. Density stratification will vary with Spring-Neap cycle and river discharge. The tide in the Bay is mixed, mainly semidiurnal, and it loses energy through turbulent mixing in the bottom boundary layer as it propagates northward Range of tide is approx. 3 feet at mouth of Bay, 1 foot at Annapolis Avg Depth: 21 ft Max Depth: 174 ft

Salinity and Tidal Currents

Chesapeake Bay Hypoxia

Spatial Variability vs. Temporal Variability In any monitoring program or research endeavor to understand the bio-physical processes that dominate ecological systems we face the spatio-temporal dilemma, we can be Spatial intensive – lower temporal resolution – or Temporal intensive – lower spatial resolution May loose vertical dimension But, water quality parameters exist in the spatiotemporal domain

Resolving the Spatio-Temporal dilemma HydroLab DS 5 REMUS 100 NOAA Annapolis Buoy

Monitoring Locations

Severn River D.O. 2010

Severn River 2011

REMUS 100 Remote Autonomous Environmental Unit s Physical Specs: Manufacturer: Hydroid Body Type: Torpedo Size (LxWxH): 1.60m x 0.19m x 0.19m Body Size (LxWxH): 1.60m x 0.19m x 0.19m Hull Material: Aluminum Weight: 37.00kg Maximum Depth: m Self-Righting: Yes Obstacle Avoidance: No Endurance (nominal load): 22 hours -

Mission: Round Bay, Severn River hypoxia

Mission: Round Bay, Severn River hypoxia (Aug 13, 2010)

Mission: Round Bay, Severn River hypoxia (Aug. 13, 2010)

Mission: Severn River June, Round Bay to College Creek RBN USNA WT 7.1 REMUS (6-8 AM)SRK weekly monitoring (8 AM – 2 PM)

Hypoxic Squeezing

Hypoxic Squeeze Index Rsqrd=.72

Severn River Hypoxic Squeezing CS SRO ASQSR7 CHS SR5 WMS SLT BRW

Route 50 bridge Bottom Do, mg/l

Increasing the importance and relevance of buoy data and AUVs, building the network Hindcasting water quality parameters What if you could extract buoy information and cat it throughout the rest of a small tributary. Theoretical Approach: Slice up the tributary into 1 meter sections. Consider well mixed within a section; stratification occurs between sections. As a result conservative properties may be modeled as Gaussian distribution.

2012 Severn River Forecasts

The Future Naval Estuarine and Coastal Ocean Observation System

Conclusion It is important to understand the complete system when attempting to make important policy decisions regarding restoration. Physics dominates and controls the system, no coriolis and no sloshing of water in and out by tides, Hypoxia and anoxia are locally controlled (it’s the creeks!!!) Susquehanna River is NOT the main polluter to Severn and South Rivers. Severn is not getting worse, but its not getting better either. Need more studies on restoration effectiveness, including BAAs, long-term studies and downstream measurements Use of technology like REMUS, CONMONS, and a more complete observing system will allow for better modeling, and therefore better policy decisions. Initial hindcasting results promising