One of the most important challenges, when designing monitoring facilities in remote locations, is resilience. Remote tide gauge systems operate in extremely harsh environments and require robust communications systems that almost never fail and are capable of storing large amounts of data locally as an extra protection for data. Scientists from the National Oceanography Centre (NOC) are therefore upgrading the South Atlantic Tide Gauge Network (SATGN) to include the latest low power dataloggers with built-in satellite telemetry capability – the SatLink 3 from OTT Hydromet.

The SATGN is maintained and operated by the National Oceanography Centre, which is the UK centre of excellence for sea level monitoring, coastal flood forecasting and the analysis of sea levels. It is the focus for marine water level research in the UK and for the provision of advice for policy makers, planners and coastal engineers.

The SATGN measures sea levels in some of the most remote places on Earth. Monitoring sites include Antarctic locations such as Rothera and Vernadsky; located around 1,400 km below the southern tip of Argentina. Prior to the installation of this network there was a lack of information on sea level variations in the Southern Atlantic and a bias in tide gauge records towards the more densely populated Northern hemisphere. Over the last 30 years data from the SATGN have improved estimates of global sea level change, such as those reported by the Intergovernmental Panel on Climate Change.

The NOC at Liverpool operates and maintains the SATGN providing near real-time sea level data for operational purposes and scientific research. This has helped to provide a long-term sea level record that is used by UK scientists and the wider scientific community to monitor the Antarctic Circumpolar Current (ACC) variability. The data is also being used to help in the ‘ground truthing’ of satellite altimetry as well as the evaluation of climate variability on various timescales including longer term changes. In addition, the data is being used by local communities to provide essential information for both government and port authorities.

Monitoring/telemetry system upgrade

In recent years, the SATGN has undergone a refurbishment programme to reduce running costs and to safeguard local populations and infrastructure by providing tsunami monitoring capability and improving resilience. These new gauges couple Global Navigation Satellite System (GNSS) land level monitoring technology with tsunami capable radar and pressure sensors, transmitting data in near real-time by satellite based communications systems to operational monitoring centres.

As part of this NOC ongoing program, the tide gauges’ main datalogger and transmitter have been upgraded to incorporate OTT’s new Sutron SatLink3. The first site to receive this upgrade was the Vernadsky station located in Antarctica, which is now operated by Ukrainian scientists and is soon to be followed by the tide gauge at King Edward point, on the South Georgia islands.

A further advantage of the upgrade is the SatLink3’s ability to communicate via Wi-Fi with wireless devices, including smart phones, tablets and computers. This means that local staff can connect wirelessly to the logger from a few metres away, which is a major advantage during inclement weather conditions.

Sensors

The SatLink3 datalogger is capable of accepting readings from a wide variety of sensors, with 2 independent SDI-12 channels, 5 analogue channels, one 4-20 mA channel and 2 digital inputs. The Vernadsky station includes a barometric pressure sensor, a radar level sensor installed over a heated/insulated stilling well (keeps the inner core free of ice) and two OTT PLS pressure level sensors which provide accurate measurements of water depth.

The network is using the Geostationary Operational Environmental Satellite (GOES) to transmit data. GOES is operated by the United States' National Oceanic and Atmospheric Administration (NOAA)'s National Environmental Satellite, Data, and Information Service. One minute averaged data is transmitted every 15 minutes. The data is then made freely available on the IOC Sea Level Station Monitoring Facility web site www.ioc-sealevelmonitoring.org/list.php.

Summary

By upgrading to the SatLink3 logger/transmitter, the NOC is enhancing the resilience of the South Atlantic Tide Gauge Network. Jeff Pugh from the Marine Physics and Ocean Climate Group at the NOC, says: “The data from this network informs models that assist with projections relating to climate change, and others which provide advance warnings that can help protect life and property. Given the remote locations of the monitoring sites, it is vitally important, therefore, that the instruments are extremely reliable, operating on low power, with very little requirement for service or spares. By transmitting almost live data via satellite, these monitoring systems enable the models to deliver timely warnings; advance notice of tsunami, for example, can be of critical importance.”

Satellite telemetry is becoming increasingly popular in many other parts of the world. “Some government and non-commercial organisations are able to utilise a variety of satellites free of charge,” explains OTT’s Nigel Grimsley. “However, the cost of transmitting data via satellite has reduced considerably recently, and now rivals the cost of cellular communications.”

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Following a competitive tendering process, the Environment Agency has awarded OTT Hydrometry (UK) with a national contract to supply submersible pressure sensors to be used in water level measurement applications associated with surface water, groundwater and tidal water monitoring.

The contract is part of a joint procurement exercise with SEPA (Scottish Environment Protection Agency) and NRW (Natural Resources Wales).

The contract applies to Lot 6 of a telemetry and control equipment tender, which covers digital output ceramic diaphragm sensors with SDI:12 and Modbus output, for use where sensors require regular cleaning or where surrounding water is susceptible to freezing during the winter.

Under the contract, OTT will supply the OTT PLS sensors until November 2022, with options to extend for a further two periods of 12 months thereafter. The PLS is a robust ceramic pressure cell, providing long-term measurement stability. Resistant to physical force (5 x burst pressure) and with an enclosure made of high-quality saltwater resistant steel, the PLS is suited to a wide variety of freshwater and marine applications.

As a vented probe, the PLS maintains measurement accuracy by automatically compensating for changes in barometric pressure, and a built-in microcontroller compensates for temperature effects. The sensor also applies correction values for gravitational acceleration and water density. The sensor’s robust cable has a Kevlar core, and with flexible output formats, it can be connected to a wide variety of dataloggers and outstations.

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Brad Guay is no ordinary new recruit. With a degree in Meteorology from Penn State University, he has worked for the Colorado-based Center for Severe Weather Research on a tornado research project investigating ground level conditions inside tornados. Brad worked as part of a team which deployed meteorological instruments into the paths of tornadoes at close range.

More recently, Brad worked in the sales team at Risk Management Solutions in New York City. Financial institutions use RMS models to better understand catastrophic events such as earthquakes, hurricanes and floods.

Commenting on Brad’s appointment, OTT Hydromet Managing Director, Nigel Grimsley said: “We are delighted to welcome Brad to our team; with in-depth knowledge of risk management, he understands the importance of reliable monitoring data, so he is well placed to help our customers find solutions to their monitoring needs.”

Responding to global demand for improved monitoring of nitrate in freshwater, OTT HydroMet has launched a new optical nitrate sensor, the OTT ecoN. “This is fantastic news for scientists, catchment managers, water companies, regulators and environmental consultants,” says Ronan O'Maitiu, Global Product Manager for the OTT ecoN. “In the past, customers have been caught between low-cost/limited-performance sensors and high-end technologies, for which purchase costs prevent large scale deployment. The OTT ecoN neatly fills that gap; as a continuous nitrate monitor, with minimal maintenance requirements, it can be left to monitor in remote locations, and an optional wiper makes it suitable for extended deployments.”

In addition to a low purchase cost, the ecoN also lowers the cost of ownership because it is factory calibrated for life. As an optical sensor, the ecoN provides high accuracy and low resolution without the drift and interferences of ion-selective electrodes, or the ongoing reagent and maintenance costs of wet-chemistry analyzers.

Summarising, Ronan says: “Nitrate is an extremely important contaminant of freshwater, and the ecoN has proven extremely accurate and reliable in the field, so it has been priced for extensive deployment, and we are very excited with the prospects for this technology.”

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2020 was an unusual year in many respects, but for OTT Hydromet, one of the more remarkable features of the year was an unprecedented level of orders for water level and flow monitoring equipment. Amid increasing pressure from climate change and urbanisation, OTT’s UK Managing Director Nigel Grimsley explains the growing demand for monitoring technology that enables more effective water management.

Looking back

In 1978 OTT launched the Allgomatic – a large desktop device for ‘data measurement, storage and transmission,’ – it wasn’t even called a datalogger. Prior to the Internet and mobile phones, OTT’s customers were monitoring water level in boreholes and stilling wells with dip tapes or sensors such as shaft encoders and compressed air bubblers connected to displays, dataloggers or chart recorders. Discharge calculations were based on stage measurements, possibly with a point and hook gauge, combined with manual measurements of velocity with a rotating element current meter. Raingauges were mostly operating with a collection vessel or with a tipping bucket mechanism; recording tips with a connected datalogger. Inevitably, this provided a retrospective view of water resources that was mainly useful for detecting trends and informing models.

Flood protection measures at this time were often designed to increase channel capacity and/or divert water away from sensitive areas. This may have involved engineered flood defence infrastructure with higher flood defences and straighter channels. Flood plains were increasingly used for agricultural, commercial or residential development, and the creation of ever-growing areas of impervious concrete and asphalt increased flood risk at a time when climate change was starting to increase the frequency and severity of severe weather.

Looking forward

Jump forward to today and flood management has changed dramatically - Natural Flood Management (NFM) is now regarded as a more effective and sustainable strategy. Flood risk is now addressed on a wider catchment scale so that upstream initiatives do not have negative effects further downstream. This catchment based approach has meant that water managers are increasingly looking for solutions that employ techniques which work with natural hydrological and morphological processes and features to manage flood waters. These NFM techniques include the restoration, enhancement and alteration of natural features such as flood plains. However, there are many other ways in which NFM can help to lower peak flow and decrease flood risk. Tree planting for example, intercepts rainfall and overland flow, increases water infiltration into soil, and provides important connective habitat for wildlife, as well as providing increased carbon storage.

Tomorrow’s technology

In addition to the provision of baseline data, monitoring systems are also necessary for measuring the effectiveness of mitigation measures and providing timely warnings when alarm conditions arise. In order to better understand catchments, groundwater and surface water levels should be correlated with upper catchment monitoring which includes the measurement of meteorological parameters.

The demand for high intensity monitoring is growing rapidly, as water managers demand lower levels of uncertainty in their monitoring data, and seek to exploit the advantages of networks of continuous monitors. The high volumes of orders that OTT received in 2020 featured many networkable sensors such as the OTT ecoLog 1000; a self-contained surface and groundwater level logger with two-way communication for smart phones and tablets. Remote sensors were also highly popular, including the OTT SVR 100 surface water velocity radar and the OTT RLS non-contact radar level sensor. The volume of dataloggers with satellite communications capability is also increasing as network managers seeks to exploit the benefits of reduced data transmission costs.

The demand for better monitoring is driving the development of OTT’s latest hydrometeorological technologies, which can be summarised in four categories:

1. Accurate, reliable, low-power, smart sensors
2. Flexible, intelligent, easy-to-use dataloggers
3. Reliable, appropriate, cost-effective telemetry with multiple transmission options and redundancy capability
4. Customisable, easy-to-use, insightful, web-enabled, data management software

With the benefit of insights from comprehensive real-time monitoring networks, collecting high intensity data from multiple points, water managers will be able to make better informed, defensible decisions.

The latest durable, reliable, flexible and cost-effective data logger/transmitter to deliver data you can trust.

OTT HydroMet, a global leader in hydrologic and meteorologic instrumentation and solutions, introduces the Sutron XLink family, the Xlink 100 and 500, for the gathering and transmitting of environmental data. XLink 100/500 combines easy to use, intuitive software offering versatility and programmability. This combination assists the user to gather, store, and access large amounts of data using either cellular or Iridium transmission. The XLink 100/500 seamlessly integrates most environmental sensors, including smart, digital, and analog, while supporting common measurement protocols and interfaces, including SDI-12.

“We are very excited about this product launch, it builds upon the success of its predecessor, the xLink-1 family, and on the horsepower, ease of use, modularity and flexibility of the Satlink3 family combined with over 100 years of building quality and durable products to offer best in class site controller at a very competitive price”, says OTT HydroMet Global Product Manager Sherif Ahmed.

Accurate Data Collection and Remote Access

The new XLink family is ideal for any hydrologist, meteorologist, researcher or scientist who needs to collect accurate time series measurements from ur-ban environmental or remote monitoring stations. The remote capability via cellular or Iridium satellites allows users to access data from anywhere at any time. Remote two-way communication further saves valuable time with the capability to modify the logger’s configuration or turn on or off instruments. Similarly, the XLink 100/500 ‘s Wi-Fi capability allows quick setup and access to data stored on the logger from a smartphone or tablet. Its quick adaptability from one communication method to the next is due to its plug and go mo-dem, which requires only a quick switch of modules. This ensures that the logger can easily adapt to new developments in telecom technologies.

Simple, Easy to Use and Customizable

The operating software for the XLink, LinkComm, offers a wide variety of sen-sor templates, with wiring assistance and no additional programming required to use, but can also be adapted beyond the standard configuration to meet more complicated requirements. Python scripts can be easily used to make measurements and transmissions beyond standard configuration or to com-municate with external modems, displays and much more.

Increased Security and Data Collection Capacity

The XLink 100/500 is capable of measuring 32 environmental parameters simultaneously, enabling more complex configurations on site using just one logger. In addition, the new logger has the capability of storing up to 1 million readings. In the event of communication interruption, data loss risk is reduced as the data can be logged and stored on the device until it can be retrieved by a technician. Data security is at the heart of the design, with three access control levels to protect setup, maintenance and data from unwanted access. In addition, data can be encrypted using IP protocols, such HTTPS or FTPS, or password protected during transmission to the server.

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The science behind nutrient pollution in rivers is still poorly understood despite the fact that nitrate and phosphate concentrations in the UK’s rivers are mostly unacceptable, although an element of uncertainty exists about what an acceptable level actually is. Key to improving our understanding of the sources and impacts of nutrient pollution is high-resolution monitoring across a broad spectrum of river types. In the following article, Nigel Grimsley from OTT Hydrometry will describe relatively new technologies that have overcome traditional barriers to the continuous monitoring of phosphate and nitrate.

Background
Phosphates and nitrates occur naturally in the environment, and are essential nutrients that support the growth of aquatic organisms. However, water resources are under constant pressure from both point and diffuse sources of nutrients. Under certain conditions, such as warm, sunny weather and slow moving water, elevated nutrient concentrations can promote the growth of nuisance phytoplankton causing algal blooms (eutrophication). These blooms can dramatically affect aquatic ecology in a number of ways. High densities of algal biomass within the water column, or, in extreme cases, blankets of algae on the water surface, prevent light from reaching submerged plants. Also, some algae, and the bacteria that feed on decaying algae, produce toxins. In combination, these two effects can lower dissolved oxygen levels and potentially kill fish and other organisms. In consequence, aquatic ecology is damaged and the water becomes unsuitable for human recreation and more expensive to treat for drinking purposes.

In its State of the Environment report, February 2018, the Environment Agency said: “Unacceptable levels of phosphorus in over half of English rivers, usually due to sewage effluent and pollution from farm land, chokes wildlife as algal blooms use up their oxygen. Groundwater quality is currently deteriorating. This vital source of drinking water is often heavily polluted with nitrates, mainly from agriculture.”

Good ecological status
The EU Water Framework Directive (WFD) requires the UK to achieve ‘good status’ of all water bodies (including rivers, streams, lakes, estuaries, coastal waters and groundwater) by 2015. However, only 36% of water bodies were classified as ‘good’ or better in 2012. In the UK, nutrient water quality standards are set by DEFRA, so for example, phosphorus water quality standards have been set, and vary according to the alkalinity and height above mean sea level of the river. Interestingly, the standards were initially set in 2009, but in 75% of rivers with clear ecological impacts of nutrient enrichment, the existing standards produced phosphorus classifications of good or even high status, so the phosphorus standards were lowered.

Highlighting the need for better understanding of the relationships between nutrients and ecological status, Dr Mike Bowes from the Centre for Ecology & Hydrology has published research, with others, in which the effects of varying soluble reactive phosphate (SRP) concentrations on periphyton growth rate (mixture of algae and microbes that typically cover submerged surfaces) were determined in 9 different rivers from around the UK. In all of these experiments, significantly increasing SRP concentrations in the river water for sustained periods (usually c. 9 days) did not increase periphyton growth rate or biomass. This indicates that in most UK rivers, phosphorus concentrations are in excess, and therefore the process of eutrophication (typified by excessive algal blooms and loss of macrophytes – aquatic plants) is not necessarily caused by intermittent increases in SRP.

Clearly, more research is necessary to more fully understand the effects of nutrient enrichment, and the causes of algal blooms.

Upstream challenge
Headwater streams represent more than 70% of the streams and rivers in Britain, however, because of their number, location and the lack of regulatory requirement for continuous monitoring, headwater streams are rarely monitored for nutrient status. Traditional monitoring of upland streams has relied on either manual sampling or the collection of samples from automatic samplers. Nevertheless, research has shown that upland streams are less impaired by nutrient pollution than lowland rivers, but because of their size and limited dilution capacity they are more susceptible to nutrient impairment.

Monitoring technology
Sampling for laboratory analysis can be a costly and time-consuming activity, particularly at upland streams in remote locations with difficult access. In addition, spot sampling reveals nutrient levels at a specific moment in time, and therefore risks missing concentration spikes. Continuous monitoring is therefore generally preferred, but in the past this has been difficult to achieve with the technology available because of its requirement for frequent re-calibration and mains power.

High resolution SRP monitoring has been made possible in almost any location with the launch by OTT Hydromet of the the ‘HydroCycle PO4’ which is a battery-powered wet chemistry analyser for the continuous analysis of SRP. Typically, the HydroCycle PO4 is deployed into the river for monitoring purposes, but recent work by the Environment Agency has deployed it in a flow-through chamber for measuring extracted water.

The HydroCycle PO4 methodology is based on US EPA standard methods, employing pre-mixed, colour coded cartridges for simple reagent replacement in the field. Weighing less than 8kg fully loaded with reagents, it is quick and easy to deploy, even in remote locations. The instrument has an internal data logger with 1 GB capacity, and in combination with telemetry, it provides operators with near real-time access to monitoring data for SRP.

The quality of the instrument’s data is underpinned by QA/QC processing in conjunction with an on-board NIST standard, delivering scientifically defensible results. Engineered to take measurements at high oxygen saturation, and with a large surface area filter for enhanced performance during sediment events, the instrument employs advanced fluidics, that are resistant to the bubbles that can plague wet chemistry sensors.

Environment Agency application
The National Laboratory Service Instrumentation team (NLSI) provides support to all high resolution water quality monitoring activities undertaken across the Agency, underpinning the EA’s statutory responsibilities such as the WFD, the Urban Waste Water Directive and Statutory Surface Water Monitoring Programmes. It also makes a significant contribution to partnership projects such as Demonstration Test Catchments and Catchments Sensitive Farming. Technical Lead Matt Loewenthal says: “We provide the Agency and commercial clients with monitoring systems and associated equipment to meet their precise needs. This includes, of course, nutrient monitoring, which is a major interest for everyone involved with water resources.”

Matt’s team has developed water quality monitoring systems that deliver high resolution remote monitoring with equipment that is quick and easy to deploy. There are two main options. The ‘green box’ is a fully instrumented cabinet that can be installed adjacent to a water resource, drawing water and passing it to a flow-through container with sensors for parameters such as Temperature Dissolved Oxygen, Ammonium, Turbidity, Conductivity pH and Chlorophyll a. Each system is fitted with telemetry so that real-time data is made instantly available to users on the cloud.

Conscious of the need to better understand the role of P in rivers, Matt’s team has integrated a HydroCycle PO4 into its monitoring systems as a development project.
Matt says: “It’s currently the only system that can be integrated with all of our remote monitoring systems.  Because it’s portable, and runs on 12 volts, it has been relatively easy to integrate into our modular monitoring and telemetry systems.

“The HydroCycle PO4 measures SRP so if we need to monitor other forms of P, we will use an auto sampler or deploy a mains-powered monitor. However, monitoring SRP is important because this is the form of P that is most readily available to algae and plants.”

Explaining the advantages of high resolution P monitoring, Matt refers to a deployment on the River Dore. “The data shows background levels of 300 µg P/l, rising to 600 µg P/l following heavy rain, indicating high levels of P in run-off.

Nitrate
Similar to phosphates, excessive nitrate levels can have a significant impact on water quality. In addition, nitrates are highly mobile and can contaminate groundwater, with serious consequences for wells and drinking water treatment. Nitrate concentrations are therefore of major interest to the EA, but traditional monitoring technology has proved inadequate for long-term monitoring because of a frequent recalibration requirement. To address this need, which exists globally, OTT Hydromet developed the SUNA V2, which  is an optical nitrate sensor, providing high levels of accuracy and precision in both freshwater and seawater.

The NLSI has evaluated the SUNA V2 in well water and Matt says: “It performed well – we took grab samples for laboratory analysis and the SUNA data matched the lab data perfectly. We are therefore excited about the opportunity this presents to measure nitrate continuously, because this will inform our understanding of nitrate pollution and its sources, as well as the relationship between groundwater and surface water.”

Summary
The new capability for high-resolution monitoring of nutrients such as phosphorus will enable improved understanding of its effects on ecological status, and in turn will inform decisions on what acceptable P concentrations will be for individual rivers. This is vitally important because the cost of removing P from wastewater can be high, so the requirements and discharge limits that are placed on industrial and wastewater companies need to be science based and supported by reliable data. Similarly, nitrate pollution from fertilizer runoff, industrial activities and wastewater discharge, has been difficult to monitor effectively in the past because of the technology limitations. So, as improved monitoring equipment is developed, it will be possible to better understand the sources and effects, and thereby implement effective prevention and mitigation strategies.

Nigel Grimsley, Managing Director of OTT Hydrometry (UK) is urging those responsible for flood prevention and management to take action this summer to ensure they are protected before the arrival of severe weather. “Saturated soil and blocked channels contribute to the severity of flooding, but in many cases it is the location and intensity of rainfall that contributes to the speed with which flooding occurs. Early warning of intense rainfall events or blocked channels is therefore essential. Recent advances in technology mean that it is now relatively simple and low cost to set up advanced warning systems so that appropriate measures can be taken quickly and effectively,” he says.

“The early implementation of prevention and mitigation measures provides essential protection for valuable assets. For example, on a small scale, we have installed water level monitors in village streams that are prone to flooding during intense rain or when channels become blocked. On a larger scale, we have supplied 153 monitoring stations for the Harris County Flood Warning System in Texas, where flooding represents a major threat to life and property, so early warning of intense rainfall and rising water levels provide opportunities for mitigation and where necessary, evacuation.”

OTT’s latest flood warning systems provide easy access to monitoring data from PCs and smartphones. However, crucially, they are also able to automatically issue text or email alarms when rainfall or water levels approach dangerous levels, so that timely action can be taken.

For more information, visit www.ott.com/stormwater

 

The OTT Hydromet Group has launched a new web-based data management service for remote monitoring stations. “Hydromet Cloud represents a step-change in data management,” comments UK Managing Director Nigel Grimsley. “Subscribers to this new service are provided with fast, simple access to both live and historical data, which opens new opportunities for exploiting the value of ‘Big Data’.”

Packed with new features and highly cost-effective, Hydromet Cloud provides users with easy access to secure data from field monitoring sites at any time and from almost anywhere via hydrometcloud.eu or the Hydromet Cloud mobile App. Typical applications include hydrology, meteorology and water quality.

Data are transmitted from field stations through a variety of methods including satellite, cellular (GPRS/3G/4G) or wired internet connection, and stored/backed-up in the cloud.

Designed for flexibility, Hydromet Cloud enables users to create their own dashboard to quickly collate frequently viewed data, which can be displayed as plots, tables or values, and exported in a variety of formats, which enables easy analysis of trends. This facility to create a bespoke display is enhanced by a map view with colour-coded map pins (for alarm status), current data values and colour-coded parameter values highlighting alarm status. Alarms are user-defined for values, rate of change etc. and alarm messages are issued automatically by email, text or push notification on a mobile phone. Separate limits can be set for both warning and critical levels, and users can also create alarm distribution groups for notifications.

The Hydromet Cloud mobile App provides a quick and easy opportunity to view the status of an entire network or an individual monitoring station, with options to send/share data directly from a smartphone or tablet (iOS or Android). It is also possible to create and save ‘My Plots’ to quickly recall common plots of one or more parameters graphically illustrating recent data.

Hydromet Cloud provides secure infrastructure to receive, decode, process, display, and store measurement data from nearly any remote monitoring station via a cloud-based data hosting platform. Alternatively, for those wishing to conduct their own data processing, Hydromet Cloud delivers raw data (as it is transmitted by the station) using a dedicated download page, which is updated as soon as the data arrives. The system is fully compatible with the latest OTT and Sutron data logger/communication devices, in addition to a wide variety of OTT, Sutron, and Hydrolab sensors for water quantity and quality measurements, as well as Lufft meteorological sensors, third-party sensors and IP cameras.

Summarising, Nigel says: “We are very excited about the opportunities that Hydromet Cloud will create for our customers. This is the first major new product development since the acquisition of Sutron Corporation and is a great example of the synergy that has been created by merging the companies’ development teams.

“Our customers know that data serves two purposes: one, to enable the analysis of background trends, and two to quickly and easily facilitate management by exception when alarm conditions arise. Hydromet Cloud achieves both.”

In late 2014, Southern Water completed a major project to reduce the risk of sewer flooding in parts of Portsmouth and Southsea. Substantial works were undertaken to divert runoff and tidal ingress, and a ‘smart’ hydrometeorological monitoring system was installed to enable prompt diversion of excess water during periods of high rainfall. Sewer level monitoring is undertaken in real-time and intelligent raingauges (smart sensors) combine with radio telemetry to inform a computer based catchment-wide water model. This decision support system provides advance notice for staff at the Eastney pumping station that diverts large quantities of water to storage tanks during periods of heavy rain. Through the development of a smart sewer network, Southern Water has dramatically reduced the risk of flooding in Portsmouth whilst also delivering substantial environmental benefits.

Background
Portsmouth was one of the first cities in the UK to benefit from a dedicated sewerage system in 1865. At that time, the system combined foul and surface water systems, and was adequate because with less paved areas the flows were lower, and because flows were discharged into the sea untreated. Since that time, the City of Portsmouth’s drainage network has continued to develop but has remained dependent on the use of combined sewers and the Eastney Pumping Station. The city is now served by two interceptor sewers that run north to south on the western and eastern sides of the island. These interceptor sewers carry the combined sewage flows to Eastney. In dry weather, flows arriving at Eastney are screened and pumped to Budds Farm WwTW for treatment. These flows, together with treated flows from the Havant catchment, then gravitate back to Eastney and are pumped down the long sea outfall.

Historically, during periods of high rainfall, the incoming flows exceeded the capacity of the system and excess flow was pumped from the Eastney pump station to storm tanks at Fort Cumberland. These tanks have a capacity of 40,000m3 and are filled before any flows are discharged to the sea via the short sea outfall, and then emptied back to Eastney after the storm has passed. However, due to the quantity of storm water arriving at Eastney prior to the flood alleviation project, and allowing for filling and emptying the tanks, in a typical year 650,000m3 of screened wastewater was discharged via the outfall at Fort Cumberland, in the South East of Portsmouth at the mouth of the Langstone Harbour.

Approximately 60% of the catchment consists of built up areas, 80% of which drain to the Eastney pump station. This means that nearly half of the entire surface area of Portsmouth drains to Eastney, which causes extremely large flows during storm conditions. In dry weather, flows are less than 1,000 l/s. However, in storm conditions flows increase to more than 20,000 l/s.

On 15 September 2000 an exceptionally severe storm overwhelmed the Eastney pump station, causing the pump room to be flooded, which stopped the pumps and over 750 properties were flooded. Considerable investment has subsequently taken place at Eastney with the provision of a new standby pump station. However, with half of all rain that falls on the island ending up at Eastney there is still a major risk that the capacity of the pump station will be exceeded.

Portsmouth Flood Alleviations
SchemeThe majority of the flow in wet weather is surface water, so the Portsmouth Flood Alleviations Scheme was created to divert surface water to the sea instead of entering the combined sewer. This would free up capacity in the existing infrastructure, allowing it to be used to provide protection against larger storms. In total, surface flow from 34 Hectares of paved area was diverted by the project.

The flow reduction initiatives have reduced the flow arriving at Eastney to the extent that the required flood risk protection level has been achieved. In order to reduce tidal infiltration and tidal restriction of CSO operation, new surface water pipes, culverts and swales were created, and several sections of the public sewer were remediated.

Pump management
The large diesel pumps at Eastney have an enormous capacity, with a combined ability to remove 6,500 litres per second. However, they take 15 to 30 minutes to build up to full speed so advance notice is necessary. The pump station is manned 24 hours/day and a The pump station is manned 24 hours/day and a network of 10 sewer water level sensors, 4 pump monitoring systems and 4 rainfall monitors delivers data via OTT Adcon radio telemetry to a catchment software model developed by Innovyze.

Employing the latest technology, OTT Pluvio² raingauges are able to measure both rainfall amount and rainfall intensity. This is important because traditional raingauges simply supply historical data on the amount of precipitation, whereas near real-time access to precipitation intensity dramatically increases the speed with which the monitoring system is able to deliver storm warnings. Another key feature of these smart raingauges is their ability to operate reliably without the level of maintenance that is required by traditional raingauges. For example, they are able to issue alerts when maintenance is necessary.

Summarising, Rob McTaggart, technical lead at MWH says: “Collaboration with the community, and other stakeholders in Portsmouth, made it possible for the project consortium to design and implement a solution that separated surface water to provide resilience, significantly boost flood protection and benefit the environment with the minimum of new infrastructure.

“Clearly, the flood alleviation scheme has been a success and as a result, the pumps at Eastney are called into action less often.

“The early warning system appears to be working very well. Some of the rainfall prediction data, provided by external sources, can sometimes provide erroneous projections because of the localised nature of precipitation events, so it is important to have a sufficient number of raingauges to ‘calibrate’ projections and deliver the level of precision required.”

The OTT stand (No. 126) at WWEM 2016 provided the first opportunity for visitors to see the HydroCycle PO4, the latest version of the Cycle-P remote, battery powered, dissolved phosphate monitor. Designed for long-term high frequency monitoring of remote locations, the HydroCycle PO4 can be left unattended for long periods, testing up to 1,500 samples between service/reagent change. Onboard calibration with QA/QC processing and an internal datalogger ensure the reliable collection of accurate data, and telemetry options provide data access without frequent site visits.

 The latest version of the advanced Pluvio2 weighing raingauge was also on show, offering access to precipitation intensity data as well as total rainfall measurements. The real-time nature of the Pluvio2 measurements are making this a popular choice with regulatory authorities and those responsible for flood management.

 Following recent company acquisitions by the OTT Hydromet Group, new products from Sutron and Lufft attracted significant visitors attention.

 OTT also ran two Workshops on ‘Phosphate monitoring’ and ‘Low-maintenance real-time precipitation monitoring.’ Both of these addressed highly topical issues and were popular with visitors and the media.

The OTT Hydromet Group has announced a new distribution strategy for the Sea-Bird Coastal product range of water quality sensors and monitors. “These instruments fit very well with our range of water monitoring technologies,” says OTT’s European Sales Manager Marcus Meckelmann. “We also share similar customer bases, so the key Sea-Bird Coastal products will be available exclusively through OTT’s European subsidiaries and official distributors.”

The Sea-Bird products covered by this arrangement include the HydroCycle PO4 (formerly Cycle-P) phosphate analyser, the SUNA V2 nitrate sensor, the LOBO turn-key water quality monitoring system, the WQM and WQM-X water quality meters, the HydroCAT long-term deployment water quality sondes and the Hydro-pH deep water (350m) pH sensor.

In addition to the Sea-Bird products, the OTT Hydromet Group also includes leading global brands such as Adcon Telemetry, Hydrolab, Lufft, OTT and Sutron. “Our main focus is the provision of leading-edge, accurate, reliable instrumentation and telemetry systems that deliver vital data for those responsible for monitoring and managing water resources and the impacts of weather,” adds Marcus Meckelmann. “Nutrients represent a major threat to global water resources, so we are particularly excited by the opportunities presented by Sea-Bird’s low power nitrate and phosphate monitoring technologies.”

Sea-Bird’s ocean research products are also available through the OTT Hydromet distribution channels, but on a non-exclusive basis.
 

OTT Hydrometry has launched an advanced version of its ‘Cycle-P’ remote Phosphate monitor for measuring dissolved Phosphate in rivers, lakes and reservoirs. The new ‘HydroCycle PO4’ uses less reagents per test than its predecessor and the reagents have a longer shelf-life. “This means that the HydroCycle PO4 can be left in the field, for even longer periods,” says OTT’s UK Managing Director Nigel Grimsley. “With a standard sampling rate of two tests per hour (4x per hour is possible), this new instrument is able to run over 1,500 samples before a service/reagent change is necessary, so that means the monitor can be left unattended for around a month, which reduces the cost of monitoring even further.”

Battery powered and weighing less than 8Kg fully loaded with reagents, the HydroCycle PO4 is quick and easy to deploy, even in remote locations. The instrument has an internal datalogger with 1 GB capacity, and in combination with telemetry, it provides operators with near real-time access to monitoring data for Phosphate; a critically important nutrient in surface waters.

The quality of the instrument’s data is underpinned by QA/QC processing in conjunction with an on-board NIST standard, delivering scientifically defensible results, and enabling users to spend less time checking data quality and more time analysing what the data means. The HydroCycle PO4 methodology is based on US EPA standard methods, employing pre-mixed, colour coded cartridges for simple reagent replacement in the field.