According to the National Oceanic and Atmospheric Administration’s (NOAA) National Weather Service, in the United States, the annual damage due to floods cost the nation USD 5 billion annually, while losses due to droughts average USD 10 billion per year. In addition, the country’s freshwater supply is critically stressed by a growing population, especially in environmentally sensitive areas along the coasts. The inconsistent availability of water along with the increasing demand is driving many government jurisdictions to regulate and monitor this critical resource.
One way to meet these requirements is to gather and analyze water quality and quantity data as it travels from source to consumer and back. Water monitoring data is not only used for operational decision making and historical recordkeeping, but also to evaluate the effect of measures implemented to improve water resource management. This article looks at six stages of the water process and the opportunities for monitoring to improve delivery, regulation and emergency response.
Water sources can be divided into two broad categories: Surface water and ground water. Surface water includes all water that stays on the surface of the Earth like lakes, reservoirs, rivers and streams, whereas ground water is water contained in aquifers that are below ground. Both source types can be monitored with sensors.
With water source monitoring, government agencies can collect information about the quantity and quality of water available. Monitoring systems that have integrated satellite-based communication capabilities help to cut down the costs associated with gathering and analyzing data while making government agencies more responsive to emergencies or changes in water sources.
Case Study: Observation Wells with Satellite-Based Communication Systems
Government-owned observation wells in the state of Kansas dot the banks of Lower Republican River, which is a major source of water for the state’s farmers and is highly connected with the local water table. The observation wells are used for gathering data about the water level in the alluvial aquifer throughout the water year, and correlating this data with rainfall and streamflow figures for predictive modeling purposes. The state is also interested in the impact of farming and other activities on the water quantity.
In the past, water level data was gathered manually or semi-manually by a hydrological technician who was scheduled to drive to each well and either measure the distance to the water or download data from an electronic data logger installed on the site. To eliminate the need for regular site visits, AMCi, an environmental and water monitoring solution provider, developed a monitoring system that sends data over satellite from the electronic data loggers to the state’s water management offices.
As a result of installing the system, the State of Kansas government was able to reduce man hours, fuel costs, risk and insurance required for this monitoring activity. The monitoring system also helped to minimize data loss and reduce maintenance costs by sending alarms if the installation had broken down or was vandalized, or in case of flooding, where the electronic equipment was at risk of being damaged by water.
“To address growing water resource challenges, the National Weather Service is putting more emphasis on forecasting the full spectrum of flows ranging from droughts to floods.” — Gary Carter, “Working Together to Live With a Limited Water Supply”, National Weather Service, 2005.
Water flow is measured in cubic feet/second or gallons/min and is calculated using depth and velocity data of a stream. The satellite-based communication terminals allow flow monitoring data from devices like stream gages or agricultural water meters, to be collected in a central location in near real-time. They also notify government agencies of water events or monitoring equipment breakdowns and consequently allow them to respond quickly to emergency situations.
Flow forecasts are used for optimizing the operation of water resource systems, such as reservoir operation, flood control, shipping commerce on rivers or potable and industrial water supply. Flow monitoring is also used for habitat protection, including maintaining minimum instream flow requirements in natural rivers.
The United States Geological Survey (USGS) uses a system of stream gages to monitor flow rates in major rivers and streams. Stream gages use float, pressure, optic, or acoustic sensors to determine the height of water in a stream and calculate discharge (flow). Information from these sensors is used to determine water availability and predict likelihood of droughts or floods in specific regions of the country. USGS publishes near real-time data that shows the stages of all the stream gages that they measure.
In addition to monitoring and sending data from sensors, satellite-based communication terminals can be used to remotely control equipment such as pumps, valves, or gates. For example, in canal management, the integrity of a canal can be compromised in heavy rain storms when the canal is overfilled and spills over. Spill gates, which lead water back into natural drainage systems to protect the canal in case of flooding, are impractical to manually operate due to difficult driving conditions in heavy rain storms. These gates can be remotely operated at low cost using two-way satellite communications equipment. If the canal is used for delivery of water to customers, head gates that direct water into each lateral (sub-canal) can also be controlled remotely to decrease costs and improve customer service.
During the water consumption process, there are many opportunities to monitor the water and wastewater flow rate, level, and quality. About half of water consumed in the United States is used for thermoelectric power generation, with irrigation being a close second.
In thermoelectric-power generation, flow rate monitoring and control ensure that correct amount of water enters the plant. Reservoir or tank levels can also be monitored to ensure that enough water is available for the electricity generation process. In farming activities, to avoid water waste and to conform to conservation mandates, water monitoring systems can ensure that neither too much nor too little water is used. Both weather and soil moisture sensors can be monitored and data sent to a central location for analysis. Information can then be fed to irrigation systems which can be controlled remotely according to soil requirements. Consequently, farmers can optimize yield of crops while decreasing water usage and costs at the same time. In all applications, water that is returning to the water table can be monitored for quantity and chemistry.
Water Monitoring In Agriculture
The agricultural industry is a major user of water management technology because both costs and revenue depend highly on water. The following are some examples of remote monitoring applications that help decrease costs and increase productivity of farms.
� Sprinkler control
� Low-flow irrigation system (micro-irrigation) control
� Water meter data collection
� Soil moisture sensors to start/stop irrigation when needed
� Tank and reservoir level sensors and alarms
� Valve and pump monitoring and control of on/off state or rate of flow
When water monitoring installations are in place, there is also an opportunity to tie other assets into the existing system. For example;
� Greenhouse temperature and humidity monitoring and control
� Livestock waste lagoons level to avoid overflow
� Pig and poultry farm temperature monitoring and control
� Chemical and other storage tanks
STAGE 4 — WATER CONSERVATION
Water conservation activities are closely linked with water consumption activities. The more closely water consumption is monitored, the easier it is to implement water conservation initiatives.
Case Study: Agricultural Water Meters and Water Accounting
In Western states of the US, water rights are separate of land and can be bought and sold as an independent resource. When water becomes scarce, senior right holders are the first to receive water, while junior right holders may be cut off from supply. Water flow and other consumption data is used in water accounting to support administration of water rights.
State government-mandated water meters for regulatory purposes are installed on all farms for the purpose of water accounting. While in the past, water meter readings were either self-reported by farmers or collected manually by agency technicians who periodically drove to the various meter locations, today’s conditions ask for more accurate and timely information.
Using satellite-based reporting systems allows state governments to collect near real-time information on the amount of water delivered to each farmer. State governments can make sure each farmer does not exceed the authorized yearly amount of water or authorized rate of use. In addition, soil moisture sensors installed deep in the ground are used to measure the amount of water percolating into the water table. By returning water into the aquifer, the farmer gets credit for unused water and can ask for this water out of priority when the resource is scarce.
Water quality monitoring and wastewater monitoring involve analyzing the physical, chemical and biological character of water and looking for factors that may pose a risk to human and livestock health as well as the environment. Examples of parameters that can be monitored include:
Water quality sensors can be installed in reservoirs or downstream from potential contamination source as part of a larger water monitoring system. If ground water contamination occurs, chemistry sensors in observation wells enable plume detection and tracking. Once a certain threshold of chemical is reached, satellite communication terminals connected to the sensors are used to transmit this information allowing quicker response to changes. The timeliness and accuracy of water quality data leads to many benefits including reduced costs associated with clean-ups and increased public safety.
STAGE 6 —WEATHER MONITORING
Weather events have significant impact on water quality and quantity. Satellite-based monitoring systems can be used to reliably transmit weather station data, monitor for events like floods or overloading of sewer systems and feed data into irrigation and other water management systems. Weather conditions and events that are monitored include:
� Rainfall intensity and duration
� Temperature
� Solar radiation
� Wind direction and speed
� Relative humidity
� Soil moisture
� Leaf wetness
� Snow pack (SNOTEL systems)
Case Study: Flood Water Management
Riverside County, California manages over 20 flood water basins with dams or other mechanisms to capture water and prevent it from moving downstream. Used mainly during the wet season, these reservoirs play an important role in preventing flood damage in the county.
The county recently replaced its outdated and unreliable radio-based observation with a satellite-based remote monitoring system designed by AMCi. The solution includes sensors that monitor the water level in the reservoirs and sends status messages every 24 hours. During a possible flood event, the satellite terminals are re-configured remotely to send level information every hour or even every 10 minutes, depending on the need of the county.
The terminals are also configured to notify country officials of sudden “up” or “down” events in the reservoir levels. Sudden “up” events warn that a reservoir is about to overflow while sudden “down” events may signify dam failure — either of which require immediate action. Rain gages high in the drainage system help predict the amount of water that will need to be managed.
In this application, it was important to use equipment that was not dependent on terrestrial systems because, in the county’s experience, terrestrial-based communication terminals are more likely to fail in a rain event, when they are most needed. A satellite-based application was the ideal solution.
Monitoring Benefits
Gathering and analyzing water quality and quantity data as it travels from source to consumer and back is a vital component of managing this critical resource. Water monitoring systems, which include sensors and satellite-based communication terminals, offer agencies responsible for water resources the ability to receive information in near real-time without the costs associated with having personnel travel great distances to collect historical information. Water monitoring systems with satellite-based communications provide the capability to receive notifications and alarms in near real-time to enable faster emergency response and reduce costs. Finally, information collected with these systems also provides agencies the tools and knowledge to implement everything from water source monitoring systems to water conservation initiatives.
For more information, access http://www.skywave.com or http://www.amc-wireless.com.
Geoffrey Bruce-Payne joined SkyWave Mobile Communications in 2005 in Product Management and Marketing, and has more than 15 years of experience in the telecommunications industry. As Manager of the Field Application Engineering group, Geoff is responsible for global training, consulting and engineering services for SkyWave. Prior to joining SkyWave, Geoff held progressively senior positions leading product management and product marketing teams with Nortel Networks, Innovance Networks and Ciena. He has worked with customers in various industry segments involving remote monitoring and control. Geoff holds a Bachelor of Engineering (Electrical) degree from Carleton University in Ottawa.
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Water management with satellite technology
Emergency notifications through satellite:
� Receive immediate alerts when safety thresholds are reached to control flooding or react to changes in water quality
� Reduce costs by knowing when expensive equipment may be flooded
Data communications through satellite:
� Download complete data from data loggers and remote meters
� Improve data integrity by receiving data often and from a single source
� Reduce costs by eliminating the need to send technicians to remote locations