Satellite technology for dam monitoring17 February 2021
A recent webinar organised by Rezatec and AssetLife Alliance showed dam owners and operators how new proven technologies can help prioritise maintenance and upgrade works; cut non-targeted inspection and maintenance costs; and reduce health, safety and dam failure risk. Here we find out how satellite data analytics are being used for dam monitoring to improve the visibility and understanding of asset condition.
“With careful thought-through monitoring, dam owners should be able to understand exactly how their dams are performing so you know what is normal and, more importantly, what is not,” said Ian Garside, Partner and Principal Engineer at pipe renewal experts ProjectMax. “As you regulate and operate multiple dams, monitoring can go further and allow you to assess risk across the entire reservoir portfolio helping you to drive your business and regulation in an entirely different way.
“Most importantly,” he added, “good monitoring takes you from monitoring your dam reactively to proactively - with all the benefits that will bring.”
Garside went on to outline the importance of effective monitoring. From a safety perspective it obviously:
- Reduces the risk of failure.
- Meets safety and regulatory needs.
- Diminishes health and safety risk.
- Demonstrates a duty of care.
From an engineering point of view, it can identify potential failure and track evolving issues, assess remote areas and prioritise engineer deployment. In addition, non-targeted inspection and maintenance costs can be cut, driving operational efficiencies.
Garside explained how current best practice can also lead to different monitoring challenges, such as:
- Identifying unexpected performance (and bringing the unexpected to the attention of the client), evaluating it and then taking action in a timely manner to prevent dam failure.
- Verifying and consistently delivering accuracy of readings on scale – not being limited by geography, scale or complexity of issues in order to deliver accuracy and assurance around the readings and findings that are required.
- Proactively identifying and evaluating anomalous readings and trends.
Camilla Braithwaite is a Product Manager at geospatial data analytics experts, Rezatec. Founded in 2012, the company has over 50 employees - half of whom are PhD qualified data scientists or earth observation experts. Braithwaite described Rezatec as being “Geospatial AI experts who provide Software as a Service (SaaS)” and can enable business leaders to “dynamically manage ground assets and critical infrastructure remotely, at scale and in the most cost-effective way”.
Rezatec’s water product, Water SAT, is a geospatial Artificial Intelligence (AI) solution that can remotely monitor dams, water pipeline and networks at scale. The company says it enables water leaders to prioritise, plan and optimise investment in critical infrastructure from source to tap.
Braithwaite explained that the dam monitoring component of Water SAT empowers proactive management of the integrity and state of entire dam asset bases. The process traces unusual changes in ground motion and vegetation and combines satellite data feeds with advanced AI to build a retrospective baseline of dams. This does not require input from the client and is extremely efficient in providing accurate insights and alerts to unusual activity, trends and changes - all available via an interactive web platform.
“Over the past eight years we have spent a lot of time to make sure that the data we provide is highly relevant to the needs of the end user so that they are then able to make more efficient, cost effective and profitable business decisions,” Braithwaite commented.
Since 2016 Braithwaite said that there has been a “genuine evolution” in the capability of satellite technology which can now benefit those in the dam sector. “Rezatec fits into this process by being responsible for combining the most advanced AI analytics with leading edge satellite imagery and the highest number of data inputs to provide clients with highly accurate views across their entire asset base. There is no limit to the scale of coverage,” she said, adding that the company always acquire the most appropriate data such as from radar, aerial imagery, lidar or historic information etc.
“Our data science team apply our algorithms and machine learning technology, including statistical analysis, in order to interpret source data into meaningful output. Next, we drive business insight from the analyses, eg risk assessment, and generate frequent and automated updates. Finally,” Braithwaite said, “we present the results via our interactive platform.”
Rezatec said that such sophisticated analysis of satellite derived imagery and geospatial data allows for a risk-based approach to monitoring dams and reservoirs, with sub-centimetre precision. Due to the wealth of archive satellite data available, the company goes on to claim that “this technology is the only way for dam owners and engineers to look retrospectively at changes and trends over time” and “enables a historic duty of care”. Furthermore, the company said that geospatial technology is “critical in addressing asset repairs, maximising operational and infrastructure issues, while optimising capital improvement and sustainability programmes”.
“Retrospective analysis gives a better idea of how each structure behaves through time, such as water level changes or seismic activity, so we can decide what movement is normal,” Braithwaite said. “You can also complement ground monitoring with vegetation monitoring. Vegetation vigour and moisture can be used as proxies for water seepage through the dam and embankment, as well as through any pipeline on the site.”
Rezatec’s list of water clients and partners include:
- Black and Veatch
- Smart Aqua
- Affinity Water
- Utilities Kingston
- South Carolina Department of Health and Environmental Control
- Bristol Water
- St Johns River Management Project
- Central Arkansas Water
- Startex-Jackson-Wellford-Duncan Water District
Rezatec has also been working with Australian water company, Hunter Water, to monitor any potential structural and environmental changes at its Grahamstown Dam near Newcastle in New South Wales. The dam is the company’s largest drinking water storage, holding up to 182,000 million litres and provides around half of the drinking water used by Hunter Water’s customers on an ongoing basis.
Daniel Turnbull, a Dam Safety Engineer at Hunter Water contacted Rezatec about 18 months ago.
“At that point,” Turnbull explained, “I was struggling to come up with effective ways of monitoring movement at one of our key dam sites which is the largest dam we have and supplies water to Newcastle and the Hunter Valley. In addition, some of the issues around aspects of this dam are quite unique.”
At a maximum height of 12m, there is a total length of over 5km of embankment at Grahamstown Dam. The structure is also of extreme consequence due to downstream communities.
“What is unique,” Turnbull said, “is that the dam is located in a coastal sand system and the majority of the dam is constructed of sand. The dam was built linking up the high points of sand dunes but has a really solid clay core in the centre which is our watertight seal. At the top, the clay core is 8m wide and 12m high and is robust and supported with mechanically placed sand shoulders.”
When looking for a survey monitoring network for the dam, Turnbull wanted something to give more coverage than traditional survey techniques, as they already knew that the dam’s sand shoulders move a reasonable amount on a day-to-day basis. Another challenge was an 80km per hour, two-lane road running along the top of part of the southern embankment which posed increased health and safety issues for staff needing to access that part of the dam.
Turnbull also looked at remote sensing applications. Although drone monitoring would give good coverage of the embankment, he was not overly happy about the accuracy and thought it would be quite expensive if required several times a year. In addition, as the dam is located not far from Newcastle airport, there would be logistical problems with air traffic control and flight movement which would become a hindrance if trying to get this done in an efficient manner.
Finally, Hunter Water contacted Rezatec and undertook a trial which was a two-year retrospective analysis and looked at how to display data and the provision of an online portal.
“When we found out about Rezatec’s innovative monitoring service we were very excited about the capability to improve how we monitor our assets,” Turnbull commented. “Their analytics are very accurate and were able to detect movements associated with historical works that had taken place, that Rezatec had no knowledge of. We are also able to see trends of movement at more frequent intervals than would be practical with traditional survey techniques, all achieved with zero risk to on-site personnel.”
Following this successful initial deployment, in July 2020 Hunter Water moved forward with a three-year subscription with Rezatec to monitor Grahamstown Dam.
“Once a month we have a meeting to talk through the results captured during the previous month. A lot of the time we don’t see much movement but if there are excessive amounts, Rezatec will bring it to our attention and I can send guys out to have a more detailed look or start investigations if perceived to be an issue,” Turnbull said.
As well as monitoring surface movement, Rezatec also looks at moisture and vegetation growth on the dam. Excessive vegetation growth may indicate leakage.
“When we have a lot of rain in the area the water table is quite close to the surface on the downstream side of the dam, and so we always have trouble determining what might be a leak from the dam and what is the natural water table downstream. But with Rezatec,” Turnbull added, “monitoring gets a better grasp on where leakage may be coming from.”
Rezatec’s technology has been described as a game-changer for dam owners and operators, with the ability to remotely monitor infrastructure accurately and frequently, without sending teams into remote locations.
“From our first encounter with Rezatec, they have been great to work with,” Turnbull said. “We are very confident in the capability of Rezatec’s technology and this subscription will help enhance our monitoring of Grahamstown Dam.”