Lake Stratification - US Army Corps of EngineersProject Overview
The US Army Corps of Engineers - Pittsburgh District maintain and operate reservoirs in Pennsylvania, Ohio, West Virginia, and New York. The dams are constructed for selective withdrawal with output gates at multiple levels in the water column.
Monitoring the yearly evolution of temperature stratification is a critical component in many lake management and research programs due to its pronounced effects on aquatic chemistry and biology. Lake stratification develops seasonally when surface water becomes warmer (and less dense) than deeper water. This results in temperature-dependent density differences that prevent mixing and form isolated layers of water, each with their own distinct chemistry.
Among the more common concerns is the depletion of oxygen in the deeper layers of stratified lakes during the summer months. Below the thermocline, dissolved oxygen is insufficient to support most aquatic life. The US Army Corps of Engineers wanted a way to monitor and control the lake temperature at various stratification levels.
System Description
The release of overly warm surface water, or oxygen-depleted bottom water, at selective withdrawal dams could impact downstream fish populations. At a number of reservoirs across the region, the US Army Corps of Engineers Pittsburgh District obtain real-time, on-line temperature stratification data using NexSens TS110 temperature strings suspended from buoys. Every hour, temperature profile data is transmitted via license-free radio telemetry to a host computer with NexSens iChart software, which automatically posts the data to WQData.com, a password-protected website.
With the easy, on-line access provided by the NexSens system, dam operators and reservoir managers are able to selectively release water from different depths in order to maintain acceptable water quality conditions downstream of the reservoirs. Additionally, tracking stratification conditions throughout the year provides long-term data sets that aid in research efforts and the development of best management practices. | NexSens 1001 | iChart software | NexSens WQData-6 | Annual data hosting package for up to 6 field sites, additional site expansion available | NexSens 4200-iSIC | iSIC data logger with radio-to-phone telemetry | NexSens A55 | Pole/wall mounting kit | NexSens A38 | Ground kit | NexSens A11 | Battery charger, 800 mA | NexSens A41 | Omni antenna, radio frequency, 890-970 MHz | NexSens A31 | RF cable, low-loss, 10' | NexSens A76 | Telephone surge & lightning protection | NexSens MB-300 | Monitoring buoy, 30" dia. polymer-coated foam hull, 300 lb. buoyancy | Carmanah 501-A15 | LED Beacon with solar power, 15 flashes per minute (064), amber | NexSens 4100-iSIC | iSIC data logger with spread spectrum radio telemetry | NexSens A20 | Solar power kit, 5-watt. Includes solar panel, regulator, 8.5 A-Hr battery & watertight enclosure | NexSens A44 | High gain antenna, radio frequency, 3 dB | NexSens A36 | RF cable, micro-loss, 6' | NexSens TS110 | Temperature string, N sensors, S meter apart, L meters of cable (user specified) |
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