Sensor List
Thermistors are resistors that change their resistance in response to temperature in a consistent manner. Thermistors are integrated into an electronic circuit that measures small temperature changes with high accuracy. Thermistors are used in the heat pulse flowmeter as well as in self-contained probes used to measure temperature at various locations at the BAM monitoring stations. Because temperature varies with placement of the probe in the aquifer, the vertical position of the probe is always specified.
Water Pressure (level) and Temperature
Water exerts a pressure based on mass, temperature, and density. This pressure can be measured in water with a pressure-sensing diaphragm, or transducer. When a transducer is placed at a fixed location, the level of water over top of the sensor will exert a changing pressure in the transducer that varies with the head, or water depth. Pressure transducers require compensation for changes in temperature, so they are always paired with a temperature sensor.
Groundwater Velocity and Direction
The groundwater flowmeters used in the BAM project quantify the velocity and direction of groundwater flow using heat-pulse methodology. These flowmeters modify the inherent temperature of groundwater to indicate flow. This method is further discussed in the How a Heat Pulse Flowmeter Works section.
Electrical conductance (or conductivity) is a measure of the ability of water to carry an electrical current. The electrical current, is then, an indicator of the amount of salts in the water. The amount and type of salt content in water is considered to be an indication of the quality of the water. Changes in electrical conductivity can be used to trace water movement. For example, rain water is relatively pure, and has a low conductivity. Following large rain storms, flow of water from the surface can be observed moving downward in the aquifer through measurements of conductivity. Because conductivity is temperature dependent, conductivity data are expressed at a standard temperature (25° C) to simplify comparison.
Precipitation is the source of all terrestrial waters. The relationship of precipitation rates to surface and groundwater flows is somewhat intuitive; the more precipitation, the more flowing water. Rainfall in Florida varies greatly from location to location, so it advantageous to measure the rates of precipitation to gain some insight into water levels and movement in the vicinity of the monitoring stations.
Doppler Flowmeter
This is the same type of instrument as a Doppler Radar used for weather patterns. These surface water flowmeters send out sound signals that bounce off the bottom of a water body and return to a separate transducer, or sensor, that detects the course of the sound waves. The time it takes a sound wave to travel to the substrate and return to the sensor will show that speed and direction off the water flow. Doppler flowmeters are used to measure flow in the canals because flow patterns can be complex, including reversal of flow direction when the canal backs up due to changes in downgradient flow control structures,
Sensors at L30, L31NN and nearby
Station ID DBHYDRO Station Name Float & Shaft Encoder Water Pressure & Temperature Sensor Groundwater Temperature Flow Velocity & Direction Specific Conductance Rainfall Surface Water Acoustic Doppler Velocity & Level
L30 Stations (North of Tamiani Trail in WCA3B)
MW-1 x x
MW-3 x x
MW-4 x x
MW-5 x x
MW-6 x x x
MW-7 x x
MW-8 x x x
MW-9 x x x
SW-7 x x x
L31NN (South of Tamiami Trail on L31N at Midpoint of L31N Seepage Barrier)
L31NNGW1 G-3778 x x
L31NNGW2 G-3779 x x
L31NNGW3 G-3780 x x
L31NNGW4 G-3781 x x
L31NN L31NN x
L31NS (South of Tamiami Trail on L31N 2 miles South of L31N Seepage Barrier)
L31NSGW1 G-3784 x x
L31NSGW2 G-3785 x x
L31NSGW3 G-3786 x x
L31NSGW4 G-3787 x x
L31NS L31NS x
Surface Gages on L31N Canal
(Near L31NN)
N/A x
(Near L31NS)
N/A x
USGS Wells in ENP
G-3576 G-3576 x
G-3578 G-3578 x
G-3273 G-3273 x
Tree Island Stations (Tree Island 3BS1)
3BS1W1 3BS1W1_G x
3BS1W2 3BS1W2_G x
3BS1W3 3BS1W3_G x
3BS1W4 3BS1W4_G x
3BS1W1_H x
SFWMD Control Structures
S335_H (L30) S335_H x
S335_T S335_T x
(0.5 mi West of L30 on Tamiami Trail)
S356 x