Safe navigation relies on accurate hydrographic data, and collecting that data requires skilled surveyors, specialist equipment, and local expertise. For a remote island such as St Helena, located in the South Atlantic, having this capability locally is particularly important. Through its longstanding partnership with St Helena Government, the UKHO has provided loaned survey equipment and practical training to local teams. This is helping St Helena to collect vital seabed mapping data and support the safe and secure supply of goods to the island community. GIS staff from St Helena and hydrographic experts that took part in the initiative. From left to right: Ryan Benjamin, Jamie Phillips, Devlin Yon, Matt King (Hydrographic Surveyor), Joelle Henry and Luke Bargo. ## Why is supporting hydrographic capacity building important? Hydrography is the science that measures and describes the physical features of the seabed. Accurate hydrographic data underpins safe navigation, environmental management, and sustainable use of the marine environment. However, collecting and maintaining that data requires specialist equipment, technical expertise, and the ability to undertake surveys on an ongoing basis. For island nations such as St Helena, developing local hydrographic capability ensures the mariners on board vessels approaching the remote island have access to fit-for-purpose information and helps to maintain the safe and secure supply of essential food and goods for its community. Hydrographic data also enables coastal states like St Helena to gain further insights into the marine environment. Seabed mapping data provides marine scientists with information on marine habitats, as well as supporting decision-making for environmental protection and management. As a world leader in hydrography, the UKHO shares its expertise with the global hydrographic community and actively supports the UK Overseas Territories and other partners, to develop their hydrographic capabilities. In St Helena, the UKHO has provided access to specialist expertise, training, and state-of-the-art hydrographic survey equipment to undertake essential surveys within its port. By empowering local teams to collect, process, and manage hydrographic data themselves, the UKHO supports long-term resilience while improving the information used to update official navigational products. ## Building capability through practical training The capacity development has formed part of a longstanding partnership between the UKHO and St Helena Government, which aims to strengthen local hydrographic capability and support the collection of high-quality seabed mapping data around the island. Following an introduction to hydrographic surveying and the systems involved, UKHO hydrographic experts spent two weeks working alongside marine stakeholders in St Helena. They shared practical surveying techniques and provided hands-on training in the use of the UKHO’s loaned survey equipment. Staff from St Helena’s Geographical Information Systems, Marine and Meteorological departments developed the skills needed to collect, process and manage seabed mapping data independently. Seeing the seabed come to life: local teams analyse live survey data from the USV’s multibeam echosounder. ## Using new technology in St Helena Through its Hydrographic survey Equipment Loan Pool (HELP), the UKHO provided access to an uncrewed surface vessel (USV) equipped with an advanced multibeam echosounder. The all-in-one survey platform enabled the team to begin surveying the island's waters immediately. UKHO hydrographic experts then worked alongside local stakeholders, providing hands-on training and building the skills and confidence needed to operate the system safely in shallow and coastal waters around St Helena. A significant milestone for the partnership: the UKHO’s loaned USV arrives in St Helena, ready to support real-world hydrographic surveys and hands-on learning in the island’s waters. As well as supporting hydrographic surveys, USVs can be used in a range of operational situations, including search and rescue activities and environmental monitoring. This makes them a flexible tool for St Helena's marine community, while producing fewer emissions than traditional survey vessels. The initial training focused on using the USV to monitor the port environment and support the safe arrival of supply vessels. In the next phase, local teams will use the multibeam system on a local vessel to survey St Helena's coastal waters. Enabling local teams to use and maintain this technology is an important step towards building a sustainable hydrographic capability in St Helena. Devlin Yon, Head of Geomatic Services, St Helena Government, commented on the importance of this type of international collaboration, noting that: > “By bringing together colleagues from across government and providing hands-on experience with modern survey technology, we are building the foundations for a sustainable, locally managed hydrographic programme.” Kerrie Howard, PCA Programme Manager, UKHO said: > _“I am delighted that St Helena Government is the first recipient of equipment through the UKHO’s Hydrographic Survey Equipment Loan Pool. This provides them with the skills and equipment they need to collect hydrographic data, supporting both St Helena’s SOLAS commitments and wider use across government. This initiative will provide them with invaluable data to understand, manage and protect their marine environment.”_ Putting new skills into practice: the UKHO’s loaned USV operates in Rupert’s Bay as local teams gain hands-on experience collecting hydrographic data in a live survey environment. ## What happens next? This approach demonstrates the UKHO’s ongoing commitment to support its partners globally to strengthen their hydrographic capabilities. It also signals a change in how we support our partners, focusing on enabling and empowering our partners to develop their data collection capabilities. The UKHO will continue to work with St Helena and its partners, to ensure the data collected meets international hydrographic standards (IHO S-44) and UKHO’s data requirements for producing trusted products and services. While St Helena was the first beneficiary of equipment from UKHO’s HELP, the pool is currently being expanded to support more UK Overseas Territories and UKHO partner nations. As a global leader, the UKHO is proud to support nations across the globe to provide access to equipment that may not otherwise be accessible and empower local hydrographers to undertake the surveys of their own waters. Based on feedback from the hydrographic community in developing countries which the UKHO supports by providing charting services, the UKHO anticipates that the HELP will expand further in years to come to meet the demand. By providing our partners the skills and access to the equipment needed, UKHO aims to increase the quantity of modern data supplied by its partners for vital ports and to enable the development of the next generation of S-100 products.

In January 2026, the Blue Belt Programme embarked on its first expedition across the Caribbean, charting the previously unexplored waters of Anguilla, the Turks and Caicos Islands and the Cayman Islands. A team of 46 marine scientists spent six weeks aboard the RSS James Cook. Local marine scientists from each of the Caribbean nations were joined by UK scientists from the British Antarctic Survey, National Oceanography Centre, the Natural History Museum and the UK Hydrographic Office (UKHO). Through the course of the expedition, the team mapped over 25,000km² of seafloor. The seabed mapping data collected will provide the local areas with further understanding of their marine environment, supporting a range of applications such as the safe navigation of vessels, habitat conservation and biodiversity and coastal management. Ahead of World Hydrography Day, we caught up with Rosa Crespo Sanchidrián (RSC) and Matthew Bennett (MB), Senior Hydrographic Specialists, who represented the UKHO on board the vessel, to find out more and hear about the UKHO’s role, their experiences in the field, and some of the expedition’s most exciting discoveries. * * * **Can you provide an overview of the UKHO’s role in the Beyond the Reef expedition?** **RSC:** As a world-leading centre for hydrography, the UKHO was primarily tasked with conducting bathymetric surveys to measure and map the depth and characteristics of the seabed. Throughout the expedition, these insights had a range of applications, from supporting research into biodiversity to ensuring safety of navigation. Seabed mapping was especially vital to this expedition as many existing nautical charts of the region rely on data that was collected over 100 years ago. These historical measurements were made using lead line surveys which are less precise than those made by modern hydrographic surveying equipment. Conducting new surveys gave us the opportunity to greatly improve our understanding of the underwater environment. * * * **Could you provide an insight into how different hydrographic surveying techniques were used during the expedition?** **RSC:** We mainly used sonar to measure water depths. This works by emitting pulses of sound from beneath the ship and measuring the time it takes for the pulses to bounce off the seafloor and return. Sound travels at a known speed through water so we can use that travel time to calculate precise water depths. **** The instruments we used were multibeam echosounders, which send out around 1,500 soundings per second, enabling us to survey wide swathes of the seafloor in a single pass. This meant we were able to build up a detailed picture of vast areas of seafloor in a relatively short time.**** **MB:** We also used our sonar equipment to record backscatter, which helps us to identify the composition and texture of the seafloor. These work by measuring the intensity of sound reflected off the seafloor - different seafloor types reflect sound differently, allowing us to identify their characteristics. Hard bottoms such as coral or rock produce a strong return signal, while softer materials like sand absorb more sound and return a weaker signal. To verify what the sonar data was telling us, we also deployed drop cameras. These are camera systems which are lowered on a cable directly to the seafloor to visually survey the habitats below. This process, known as "ground truthing," allows us to confirm what the acoustic data suggests. In practice, the cameras confirmed that much of the seafloor we surveyed was sand! * * * **Why are hydrography and seabed mapping so important for environmental conservation?** **RSC:** Bathymetry and hydrodynamics play an important role in fish distribution. You tend to find a lot more life when the depth drops off as it is just too hot in shallower waters. Once we reached the submerged boundary of a continent, known as the continental shelf, the sea floor got deeper, and we saw lots more fish and even humpback whales. We used sonar and water column data to identify species, assess biological abundance and characterise habitats. Rocky areas have significant amounts of life compared to sandy seabeds as the variation creates habitats for fish, plants and invertebrates as well as providing shelter from predators. **MB:** The team was especially excited to find sea mounts and ridges. These are ecological hot spots drawing together all the different marine communities. Even as someone less familiar with the biology side of things, the imagery was beautiful to see. We didn’t know what we would discover, so this led to some significant surprises. At one point, we discovered a new mesophotic reef that hadn't been reported before on Malliwana Bank in Anguilla. * * * **From a hydrographic perspective, what were some of the most interesting or surprising discoveries that you made during the expedition?** **MB** : Turks and Caicos was unlike any seabed I’ve surveyed before. There were seamounts, ridges and, immense vertical drop offs going from 40m to 1000m depth in seconds. In the south of Grand Turk, we found an underwater sinkhole, or ‘blue hole,’ which was 300m wide and 100m deep. This is probably the biggest in the entire Caribbean region and has never been charted before. We found this completely by chance as we had initially planned to survey the north of the island but moved to the more sheltered south to avoid bad weather. It was very flat which was strange for this area. The first ship track line just looked like lots of messy data, so we didn’t think anything of it. The second line of the same area gave a perfect circular shape. Bathymetric survey data showing the ‘blue hole’ found during the expedition. **RCS:** We also found a major ridge to the Nort East of Turks and Caicos. Data used for planning showed lots of separate seamounts, but it turned out to be a huge continuous ridge: 70km long and almost four thousand metres high. It was exciting to realise the impact this will have on biodiversity on both sides of the ridge. The steep slopes of the ridge force nutrient-rich deep waters to rise toward the surface. This process, known as upwelling, generates food for a remarkable variety of fish and other marine fauna. Bathymetric survey data showing the sea ridge found during the expedition. The deepest point we surveyed was in Anguilla at 6,200m. To put that in perspective, this is almost 1000m higher than Everest base camp, but underneath us. It was impressive to be over the reef and see the depths yourself. It would be perfect turquoise Caribbean water, a line where the ridge was, and suddenly the water would be dark blue. * * * **Could you provide some examples of how the data collected will be used in the future by governments of various countries?** **R****CS:** Our bathymetric surveys have created a foundational dataset which has been shared with the local governments and other regional maritime stakeholders. The Centre for Environment, Fisheries and Aquaculture Science (Cefas) will use it as the basis to designate marine protected areas which help protect sensitive ecosystems from human activity. Beyond conservation, regional governments and port authorities can draw on the data in all sorts of ways. Anguilla, for example, are planning to build a marina and our seabed maps will be used to help ensure vessels can safely navigate into and around the new facility. That’s really what we mean when we refer to bathymetry as a foundational dataset: something that can be built on in whichever direction is most needed, whether that’s conservation, infrastructure, fisheries management, or safety. It lays the groundwork and others can take it from there. * * * **How was your experience working with other marine research groups? Why is this collaboration between marine science disciplines so important?** **MB:** It was interesting to see other organisations’ activities and how all our work was intertwined. For example, our bathymetry data and backscatter would help identify where tow cameras could be dropped and how deep mid-water trawl nets could be deployed to sample fish populations. **RCS:** This was a great opportunity for all the participating organisations. As scientists, the experience of going offshore and conducting surveys in the field helps us keep our skills up to date. I was initially nervous but was made to feel welcome. All the different teams were happy to share knowledge. We ended up training and supporting each other throughout the expedition. * * * **What would you say was your personal highlight of the expedition?** **MB:** There were so many highlights, I’ve never surveyed such an interesting seabed before. There was an incredible variety of features down there such as seamounts and ridges. The best point was discovering the blue hole. It had been quite an uneventful shift up until that point! **RSC:** For me it was the fish. Of course, I knew there would be fish but none of the varieties we were finding. It was interesting to work with the fisheries: we would get fish from 1000m and then sort and analyse them. It was amazing to see them under the Ultraviolet (UV) light. I found the fisheries acoustics particularly interesting. Acoustics are a core part of our work, it was fascinating to see them applied in other ways: the team used them to pinpoint where fish were located, estimate population sizes, and even identify species. I also really enjoyed working with the people on the expedition. It was quite an intense trip working twelve hours a day, but everyone was so welcoming. It was a very collaborative atmosphere and I learnt so much. Find out more about the Beyond the Reef Expedition on the Blue Belt Programme blog.

**Joseph Pearce, Lead Geospatial Specialist – Geodesy and PNT** , UKHO, shares insights from onboard the first leg of the ‘CSM2026’ survey – a collaborative seabed mapping survey, coordinated by the UK Centre for Seabed Mapping (UK CSM). Taking place off the south-west coast of the UK, this survey saw 11 organisations collaborate to gather data and insights to improve understanding of the seabed. In the early hours of Monday 20 April, the Research Vessel **Cefas Endeavour** reached its survey area off the Cornwall coastline, having departed from Lowestoft. Over the following two weeks, a team of marine scientists and experts collected seabed mapping data that will go on to support a range of activities – from safer navigation to environmental research. The team had a shared goal of collecting high-quality seabed mapping data to support a wide range of needs, with the ethos of “collect once and use many times”. The story so far: * In just two weeks, the team mapped an area of seabed around six times the size of the city of Southampton. * This is the first time this particular Marine Protected Area has been surveyed to modern standards using up-to-date equipment. * The team collected more data than planned, which allowed the survey to cover additional areas. * The survey identified several wrecks for further investigation, supporting safer navigation in the area. _Research Vessel Cefas Endeavour during static validation in Lowestoft_ ## Building the picture of the seabed In the days leading up to departure, teams from the participating organisations mobilised in Lowestoft to install, configure and test the survey equipment. UKHO surveyors carried out detailed cleansing and validation work to ensure systems were set up correctly and data could be captured to the highest possible standard from the outset. _UKHO team cleaning the multibeam echosounder transducer face in Lowestoft_ Once the vessel reached the survey area, the team in the survey suite began calibrating onboard systems. Surveyors carried out repeatability, or ‘patch’, tests to confirm the equipment was measuring data accurately and consistently. One way to do this is by surveying known wrecks, allowing the team to compare new readings with existing data and validate the results. With the equipment calibrated and validated, the team could then begin the main survey work. Using equipment such as multibeam echosounders and sub-bottom profilers, experts spent the first two weeks of the survey building a comprehensive picture of the seabed in this area. In simplified terms, the multibeam echosounder used sends out pulses in a fan shape and measures how long they take to return. Gradually, a three-dimensional image depicting the depth and shape of the seabed then emerges – this is known as bathymetry. During the first few days of the survey, the teams identified several features including: * The wreck of an unknown steamship * A large rocky feature, approximately 700 meters long, similar to formations found on Bodmin Moor and Dartmoor * The wreck of the submarine HMS M1 (which sank in 1925 and was discovered in 1999) The seabed mapping data collected during the survey underpins almost all marine activity. It helps ensure safer navigation, supports environmental protection, and informs smarter decisions about how we use and manage our seas. For some of the wrecks in this area, this was the first time they had been surveyed using modern techniques. Earlier surveys relied on older equipment and divers, providing a much less complete picture of the seabed. The rocky features were of particular interest to scientists from the Maritime and Coastguard Agency (MCA), Centre for Environment, Fisheries and Aquaculture Science (Cefas) and the British Geological Survey (BGS). They offered new opportunities to learn more about seabed habitats and how these features relate to familiar landscapes. _Bathymetry data gathered using multibeam echosounder. Presenting a potential steamship wreck in the foreground, and rocks behind._ ## Collect once, use many times By bringing together organisations from across government, CSM2026 is designed to make the best possible use of shared resources. By collecting data once and analysing it together, teams can meet different needs at the same time. During the first survey leg, scientists and surveyors worked side by side, using shared data to support a range of activities. This included collecting: * **Bathymetry** – used to create navigational charts * **Backscatter** – used to understand seabed for charts, geology and ecology * **Water column data** – used to identify and investigate wrecks This data supports a range of activities, including: * **Safe navigation -** UKHO surveyors analysed seabed mapping data to create the data sets used to update navigational charts, supporting safe passage of vessels in the area and provide a foundational data set for the rest of the survey. * **Environment monitoring -** Cefas scientists identified areas of potential environmental significance around features revealed in the data. * **Marine planning -** Historic England scientists used backscatter data (a by-product of the multibeam survey) to identify potential wrecks and inform planning for marine heritage projects. BGS scientists combined this with sub-bottom profiler data to investigate geological features such as glacial moraines, buried riverbeds and larger rock formations. This shared approach supports nautical charting, environmental research, geological analysis and operational planning – showing how collaborative surveying enables better, more joined‑up decisions about our seas. _Surveyors from the UKHO analysing bathymetry data in the survey suite onboard the RV Cefas Endeavour._ ## Starting the second leg of CSM2026 On Monday 4 May, the vessel docked in Falmouth, marking the end of the first leg of the CSM2026 survey as scientists and surveyors disembarked. The following day, a new team of maritime experts from the participating organisations joined the vessel and began the second leg, transiting back to the survey area off the coast of Cornwall. The data collected during the first leg shaped the work carried out during the second leg of the survey. It helped determine where to take seabed samples and where to deploy equipment to build a deeper understanding of the marine environment and habitats. Over the course of the survey, teams onboard worked together to unlock new insights from the data collected – demonstrating the value of collecting once and using many times. ## What's next? With both survey legs now complete, teams are continuing to analyse the data and build on the foundations established during the survey. In the longer term, it will support a wide range of marine activities – from charting and navigation to environmental management and research. CSM2026 demonstrates how a coordinated, cross-sector approach can deliver lasting value, with data used well beyond the life of the survey. Find out more about the UK CSM.

For several years, the UKHO has been actively investing in modern data technologies, including artificial intelligence (AI) and machine learning (ML), to transform how it processes, structures, and delivers critical maritime information. Recognising that large quantities of hydrographic data often come in varied formats, the UKHO is embracing AI as a means of streamlining workflows, unlocking new insights, and ultimately getting accurate and up-to-date insights to mariners faster. Central to this work has been the UKHO's data science and AI team – a group championing innovation from within the organisation. One standout member of that team is Hannah Brown, Senior Data Scientist, whose contributions have recently earned her external recognition as a finalist in the AI Champion category at the everywoman in Technology Awards. We sat down with Hannah to hear about her journey, her work at the UKHO, and her advice to others interested in a career in data science. * * * **Can you give an overview of your background and your role at the UKHO?** I’ve always been drawn to numbers and data, which led me to study Maths at the University of Exeter. From there, I joined the Met Office on a graduate scheme and spent time across a variety of roles, exploring the application of ML and AI within the context of weather forecasting. This really allowed me to see how powerful AI technologies can be when applied to specialist science sectors and got me thinking about the next step in my career. In August 2024, I joined the UKHO as a Senior Data Scientist, and, since then, my focus has been on harnessing AI across the organisation. Working with teams across the UKHO, I determine where AI and ML can make processes more efficient, and where we can build in smarter, automated approaches to difficult or time-consuming activities. * * * **Could you outline the work you have been doing on AI at the UKHO that has led to you being nominated for this award?** A major focus of mine has been on large language models (LLMs). At the UKHO, we receive data from hydrographic offices around the world, and quite a large amount of that data is text-based. Notices to Mariners, for example, often arrive as PDF documents from different hydrographic offices, each describing changes in the maritime environments they're responsible for. These documents may contain tables, descriptive passages, and references to coordinates in many different formats, and processing and standardising them can be quite time-consuming. My work has been focused on harnessing the power of LLMs to extract the key, meaningful information from those documents in a structured and reliable way. If you can make this data consistently formatted and machine-readable, you unlock a whole new range of possibilities downstream in terms of how you process the data, how you can visualise it, and how quickly you can act on updates. * * * **What kinds of impacts are being seen from this AI work at the UKHO?** The ADMIRALTY Sailing Directions teams are responsible for keeping maritime navigation publications up to date with global coverage. Having Notices to Mariners in a more structured form means it will be much easier to compare documents across regions, spot discrepancies, and keep publications up to date. Another impact is the geospatial comparisons of datasets – if you know the coordinates referenced in a document, you can cross-reference them against other relevant publications covering the same area. That kind of automated cross-checking would have been very time-consuming to do manually, but once structured data has been extracted, it is a quick and easy geospatial analysis to automate. * * * **Do you have any predictions for future directions or applications of AI in hydrography?** Something I find quite exciting is the possibility of using AI to create bespoke navigational directions. At the moment, ADMIRALTY Sailing Directions are produced for commercial shipping routes. While they are comprehensive, they are generic. What if you could take an Electronic Navigational Chart (ENC), plot a specific route, and then have an AI system generate tailored sailing directions for that exact passage? This would mean that LLMs, grounded in authoritative hydrographic data, could produce something genuinely personalised to the mariner's needs. We have begun to explore this already, and its feasibility has been demonstrated in an initial proof of concept in collaboration with data scientists from the French Hydrographic and Oceanographic Service (Shom). * * * **As the award is specifically for women in technology, how important is diversity, particularly the representation of women, in fields like technology and hydrography?** I really feel that it’s super important. In AI and ML specifically, it’s well known that developers can unintentionally encode bias into models and their outputs. The more diverse a team is in terms of gender, background, and perspective, the more representative the solutions are likely to be. I'm proud to say that the data science team at the UKHO has really positive gender representation, which I think contributes to the quality of our work. But in terms of the sector as a whole, girls are still disproportionately falling out of STEM subjects at an early age. If we don’t address that, we're narrowing our future talent pool significantly. Initiatives like the everywoman in Technology Awards are valuable not just for celebrating individual achievement, but for showing younger generations what’s possible. I also really appreciate that the awards include a category for people still at school or in study. That kind of recognition at an early stage really matters. * * * **What advice would you give to people looking to build a career in data science?** My main advice is not to be put off by the specificity of a field. Data science can be applied to a huge range of domains, and that's now led me to hydrography. I followed my interest in data, and it led me here. I would advise young people not to be afraid to dip their toes into something unfamiliar because the people who will surround you will be an incredible resource, and collaboration is where the real value gets unlocked. * * * Our technology teams make up one-third of the staff at the UKHO, spanning software and test engineering, enterprise and solutions architecture, data science and engineering, and analysis and support. Find out more about the UKHO's technology roles.

### **Calling UK government, Crown Dependency, Overseas Territory and private sector colleague participation** A clear understanding of our Subsea National Infrastructure (SNI) is crucial to the UK, Crown Dependencies and Overseas Territories. Location-based data depicting SNI is important to a range of stakeholders responsible for managing, optimising and protecting this infrastructure. A new data discovery project is underway to understand more about SNI data, its management—and which organisations are involved—and to identify areas for potential optimisation. Commissioned by the COAST (Coast and Oceans Applied Systems Thinking) group of Chief Scientific Advisors, this study aims to inform government policy making and support the planning, protection and management of subsea infrastructure in the UK, Crown Dependencies and Overseas Territories. To inform this study, we are inviting stakeholders who use or manage subsea data to share their insights by completing a short questionnaire. ## **About the project** There are many types of SNI, and COAST has recognised the value of having a 'single best view'. Therefore, COAST seeks to understand how SNI data is collected, collated, stored and shared across government organisations across the UK, Crown Dependencies and Overseas Territories. Recognising the private sector's central role as SNI data owners, users and experts, we are also keen to understand and map out government-to-private sector relationships and benefit from their expert insights. This project will create a high-level understanding of the current approach to data management and signpost areas for further investigation. Representatives from The Crown Estate (TCE), the Department for Science, Innovation and Technology (DSIT) and the UK Hydrographic Office (UKHO) are co-managing this project. A cross-government project steering group has been established to ensure they address all relevant issues. ## **Key areas to explore  ** One of the fundamental questions the project seeks to explore is what is meant by 'SNI' and which types of data this could describe. To address this, we want to gather the views of public and private sector stakeholders to consider a wide range of SNI features covering critical and non-critical assets. This could include data types that immediately come to mind, such as cables, pipelines and offshore energy, but also features that may not have been previously considered, such as components of maritime navigation, scientific monitoring and natural assets, along with new and emerging uses such as subsea data centres and carbon storage. If you use or manage SNI data, your input will be vital in shaping the future management of the UK's subsea infrastructure data. ## **Contribute to the research** We invite all UK Public Sector, Crown Dependency, Overseas Territory and Private Sector stakeholders involved in subsea infrastructure to share their insights by completing our questionnaire. We also encourage you to share this with your colleagues and peers using and managing SNI data. Please note that at no point will this discovery project ask for datasets or specific locations of assets. The survey is open until 15 September 2025. Complete the survey