5 Data Collection and Transfer Platforms
Discrete water quality measurement programs only provide a snapshot in time
much like a photograph. Continuous and unattended water quality monitoring
programs provide a stream of data on conditions, similar to a movie, which results
in a better understanding of environmental processes and the ability to capture data
during episodic events, especially at times when it is impractical and dangerous to
be in the field. Temporally intensive monitoring programs yield a wealth of data to
water resource managers and provide valuable insight into the impacts of intense
storms, low dissolved oxygen events, fish kills, and harmful algal blooms, among
others.
Temporally intensive, continuous water monitoring programs are valuable for
understanding and assessing water quality conditions and living resource habitats
and guiding watershed restoration activities. A common observance among monitoring programs, after the implementation of continuous water quality monitoring,
is the true magnitude of daily dissolved oxygen fluctuations. Many conventional
shallow water monitoring programs sample dissolved oxygen during the day when
it is practical to sample, often measuring at the peak of photosynthesis and find
dissolved oxygen levels that are considered sufficient for supporting living
resources. However, these programs miss measuring nighttime dissolved oxygen
levels. With continuous monitoring, water resource managers have found that many
of these shallow water systems have large daily swings in dissolved oxygen
concentration and, actually, go hypoxic or anoxic at night when photosynthesis
ceases and respiration significantly increases. These large fluctuations can lead to
fish kills in waters affected by algal blooms due to excess nutrients. Figure 17 shows
an example of daily dissolved oxygen fluctuations.
While some multiparameter water quality data sondes operate off of internal
batteries and have their own internal data logger, many other sensors do not.
Therefore, many monitoring stations utilize a DCP. The DCPs integrate multiple
sensors together and provide power, data logging and control capability, and in
many cases data telemetry. At their most basic level, DCPs consist of a data logger,
one or more 12 VDC batteries, a solar regulator, and a telemetry module housed
inside of a weatherproof enclosure, with one or more external solar panels, a
telemetry antenna, and some form of lightning protection. The data logger is the
heart of the system and initiates sensor measurements and controls functions based
on time or events; controls external devices such as autosamplers, pumps, or valves;
logs data; provides onboard data processing and computations; and interfaces with
telemetry devices such as telephone modems (including cellular and voice synthesized), line-of-site radio transceivers, satellite transmitters, and Ethernet and Wi-Fi
interfaces.
The data loggers, attached sensors, and telemetry devices are powered by
12 VDC batteries that are continuously charged by the external solar panels
whose voltage is regulated by the solar regulator down to safe levels. The telemetry
devices are connected to external antennas appropriate for the telemetry method.
Advances in Water Sensor Technologies and Real-Time Water Monitoring
197
Discrete water quality measurement programs only provide a snapshot in time
much like a photograph. Continuous and unattended water quality monitoring
programs provide a stream of data on conditions, similar to a movie, which results
in a better understanding of environmental processes and the ability to capture data
during episodic events, especially at times when it is impractical and dangerous to
be in the field. Temporally intensive monitoring programs yield a wealth of data to
water resource managers and provide valuable insight into the impacts of intense
storms, low dissolved oxygen events, fish kills, and harmful algal blooms, among
others.
Temporally intensive, continuous water monitoring programs are valuable for
understanding and assessing water quality conditions and living resource habitats
and guiding watershed restoration activities. A common observance among monitoring programs, after the implementation of continuous water quality monitoring,
is the true magnitude of daily dissolved oxygen fluctuations. Many conventional
shallow water monitoring programs sample dissolved oxygen during the day when
it is practical to sample, often measuring at the peak of photosynthesis and find
dissolved oxygen levels that are considered sufficient for supporting living
resources. However, these programs miss measuring nighttime dissolved oxygen
levels. With continuous monitoring, water resource managers have found that many
of these shallow water systems have large daily swings in dissolved oxygen
concentration and, actually, go hypoxic or anoxic at night when photosynthesis
ceases and respiration significantly increases. These large fluctuations can lead to
fish kills in waters affected by algal blooms due to excess nutrients. Figure 17 shows
an example of daily dissolved oxygen fluctuations.
While some multiparameter water quality data sondes operate off of internal
batteries and have their own internal data logger, many other sensors do not.
Therefore, many monitoring stations utilize a DCP. The DCPs integrate multiple
sensors together and provide power, data logging and control capability, and in
many cases data telemetry. At their most basic level, DCPs consist of a data logger,
one or more 12 VDC batteries, a solar regulator, and a telemetry module housed
inside of a weatherproof enclosure, with one or more external solar panels, a
telemetry antenna, and some form of lightning protection. The data logger is the
heart of the system and initiates sensor measurements and controls functions based
on time or events; controls external devices such as autosamplers, pumps, or valves;
logs data; provides onboard data processing and computations; and interfaces with
telemetry devices such as telephone modems (including cellular and voice synthesized), line-of-site radio transceivers, satellite transmitters, and Ethernet and Wi-Fi
interfaces.
The data loggers, attached sensors, and telemetry devices are powered by
12 VDC batteries that are continuously charged by the external solar panels
whose voltage is regulated by the solar regulator down to safe levels. The telemetry
devices are connected to external antennas appropriate for the telemetry method.
Advances in Water Sensor Technologies and Real-Time Water Monitoring
197