Teagasc Podcast on Remote Sensing

I’m the guest in the latest episode of the Teagasc Podcast series – the Research Field presented by Sean Duke.

In Teagasc we use Earth Observation technology to help us understand the status of Irish agriculture and develop tools to allow farmers to better manage their farms. Earth Observation is a branch of remote sensing, using technology like satellites and drones to measure see what’s going on in Ireland.

The satellites we use are optical (like orbiting digital cameras) and radar (which broadcast microwaves and measure how they bounce back). We can use these satellites to characterise the landscape, telling us what type of land-cover we have. They are particularly good at mapping habitats and nature. Radar and a similar technology, lidar (which uses lasers), allow us to understand the 3D world we live in, measuring the shape of the earth and objects like hedgerows.

The optical satellites work very well in helping understand the current status of field or farm and seeing how it changes or compares to the past. For grassland production, which is so important in Ireland, regular, in some cases daily observations by satellites mean we can see the grass grow. Using these images with artificial intelligence means we very reliably measure, from space the amount of grass growing in a field and the whole farm. Satellites are also very useful in seeing variation across the country at anyone time to understand the carried impacts of droughts or floods.

Across a wider landscape we can use the historical record of satellite images (going back to the 1970’s) to see how current conditions compare to normal or we can see how some land-use, like forestry, have changed over time.

One problem with using Earth Observation in Ireland is that it’s so often cloudy. Radar satellites overcome this because they can “see” through clouds but the information they relay can be difficult to interpret and be a little limited. For Ireland and Irish agriculture drones offer the solution. Modern drone are easy to fly, easy to program and can carry many different types of sensors. Drones are used to map farms to help farm planning and design, monitor crop and grass growth (especially to detect disease within a field) and they can even see underground, using thermal cameras.

Evaluating the Suitability of the Land Parcel Identification System for Assessing Land Use and Land Use Change-Related Greenhouse Gas Emission – EPA Research Report 309

EPA published the LPIS related report authored by our colleague Dr Jesko Zimmermann, Teagasc and Professor Jane Stout, TCD

The project: Identification of grassland management and land-use change using high resolution spatial databases,  is an assessment of the Land Parcel Identification System (LPIS), a high spatial and temporal resolution database developed as part of the European Union Common Agricultural Policy to assist farmers and authorities with agricultural subsidies, for the needs of national greenhouse gas reporting, including its potential strengths and limitations. The study demonstrated that, in general, reporting on arable crops showed both a high spatial and a high thematic resolution. With regard to grasslands, however, thematic accuracy was limited as different grassland categories were exchangeable (e.g. “grass” and “permanent grassland”). In addition, although more detailed categories existed (e.g. “rough grazing”), these were not always reported. Similarly, forestry was reported in the LPIS but reporting was not comprehensive.

COVID 19 from Space

The Video shows how NO2 levels have decreased this year over Italy due to the Corona Lock down.

The data was collected by the European Sentinel 5P satellite which directly measures atmospheric gases. AS well as NO2 it collects information on the concentration of gases such as SO2 and Methane.

This year’s flood

Once again, extensive areas of the River Shannon floodplain are under flood water following heavy, persistent rainfall. Current events brings to mind the recent floods of 2015/2016 when successive winter storms brought unprecedented rainfall and floods to the country. There is talk of an even more challenging situation ahead as more rainfall is forecast, and of mobilizing the army to rural areas.

This is the new normal, as changing climate brings wetter winters, more saturated soils and greater flood risk. This is not an altogether new phenomenon, in a recent interview Conor Murphy of Maynooth University outlined how flood magnitudes here have been increasing by ~5% every decade since the 1960s. In this context, any focus on past flood levels or anecdotes on flooding in areas never flooded before seem moot. Extensive winter floods are here to stay and must be dealt with.

Whatever happens in the coming days, farming communities in affected regions will be dealing with the impact of the current flood for several weeks, with fields inaccessible to livestock & machinery and delayed/ reduced grass growth and less fodder saved for next winter. In a recently published paper, I demonstrated how the 2015-2016 floods in late winter/ early spring impacted grass growth for several weeks, increasing pressure on fodder supplies at a stage when cattle should be turned out.

Sentinel-1_AWS (S1-AWS-IW-VVVH)-timelapse (1)

 

So how does the current flood compare to 2015-2016? Above is a SAR image time series from Sentinel 1 (images every 2-3 days between January 2019 and this week) measuring SAR backscatter from the surface. Water has low backscatter values (black-blue), vegetation (or non-water) having higher backscatter values (yellow hues) . The area of interest is northeast of Shannonbridge, Co. Offaly (bottom left corner), an area that has borne the brunt of winter floods in recent years. Several observations can be made:

  • Since January 2019, flood waters waxed and waned over the year, with winter floods peaking in February/March.
  • After the peak in March 2019, it took approximately 2-3 weeks (mid-April) for flood waters to clear. Soils may have remained saturated for several more weeks however.
  • Finally, winter flooding started in this region last September/ October and has peaked several times since then!

I haven’t done an analysis of current flood extent nationally, but just looking at this one part of the Shannon catchment earlier this week, current flood levels are at the same level as they were during peak flooding in 2015-2016 (red line in the image below). The challenge for farms in this situation is to stay viable/profitable in the face of sustained flooding. It is also important to remember that while flooded farmland in rural parts of a catchment may be constrained in terms of primary production, it nevertheless provides a hugely important function in minimizing flood risk in urban areas further downstream.

ExentVs2016

Images from Sentinel Hub’s EO-Browser.

My open access paper “The agricultural impact of the 2015–2016 floods in Ireland as mapped through Sentinel 1 satellite imagery” is available here .

Remote Sensing Job in Maynooth University

Maynooth University are seeking an enthusiastic Data Scientist to join an exciting new research project, SOil MOisture estimates from SATellite based Earth observations (SoMoSAT), for a period of 28 months. The research, which is funded by the Environmental Protection Agency, is seeking to develop a novel data platform to ingest, analyse and fuse multi-thematic and multi-temporal earth observation data streams, including in situ data, using advanced machine learning techniques to derive high spatial resolution soil moisture estimates for Ireland. The successful candidate will be working as part of a project team, alongside Dr. Tim McCarthy and Dr. Rowan Fealy. Details HERE

Closing Date:

23:30hrs (local Irish time) on Friday, 6th March 2020.

Please note all applications must be made via our Online Recruitment Portal at the following link:

https://www.maynoothuniversity.ie/human-resources/vacancies

Post Ref: 005721

 

More archaEOlogy

Last week, I reported on two new archaeological sites and this week I’m back with more. Apparently, it is something of a Golden Age for reporting archaeological discoveries with ~1500 reports of new monuments to the Archaeological Survey of Ireland in last year alone!

UPDATED:

Starting in Limerick, the image below has extensive earthworks over several hectares surrounding Kilcurly church. The earthworks have been classified as a possible clustered settlement, possibly associated with a substantial dwelling / house depicted on the 1657 Down Survey map of Kenry Barony.  The Civil Survey of 1654-56 mentions the presence of 10 cottages and a good dwelling house associated with this church, and some of these earthworks may be related to these dwellings. I would encourage you all to check out the SMR information online. Teagasc are currently funding PhD research into the remains of a medieval settlement at Newtown Jerpoint (Daniel O’Mahony, UCD).

In the image, north of the road, relict field boundaries, several enclosures and possible building foundations are visible. South of the road  (bottom left corner), you can see a large oval enclosure (190 m x 150 m) containing several subdivisions and possible structures.  A disused road leading to a medieval church (farmhouse, bottom center) curves around this enclosure. The church site at this location is already recorded monument, but the extent of the remains around it was not previously known. A very quick online search identified sixteenth century land records for this church that mentioned several associated buildings and a water mill.

GoogleEarth2009

Another candidate for medieval settlement remains from the Midlands. Here, a relict field system surrounds an early medieval ringfort defining a raised, drained area of land above surrounding marsh. A large square enclosure to the west shows internal subdivisions and potential building foundations.

RelictFieldSystem_roscommon

 

A third potential medieval settlement, again in the Midlands where field boundaries and potential structures surround an Anglo-Norman castle (motte) which is adjacent to a medieval church. The church itself is positioned within a larger ditched enclosure possibly of early medieval date.

DesertedSettlement_offaly

 

Some other new discoveries from around the country this week include:

A riverside enclosure (22m diameter) in Co. Limerick.

enclosure_limerick

 

Large (60 m diameter) and small (16 m diameter, 100 m SW of the large one) enclosures in Co. Mayo.

enclosures_mayo

 

A 30 m diameter enclosure in Co. Roscommon.

Enclosure_roscommon

 

Two adjacent circular enclosures (<10 m diameter) in Co. Offaly.

PossBarrows_offaly

 

Unrecorded sites such as these are vulnerable to unwitting destruction through land improvement or hedge clearance. The final images below show a 30 m diameter bank enclosing a low raised mound. The site was visible in several GE images from 2002 onwards but appears leveled in the most recent GE image. Parts of the monument below ground will still be present and a trace of it may well be visible in future GE images.

barrow_corkbarrow_cork_removed

 

Reports for these sites have been issued, or are being prepared, for the National Monuments Service (NMS). In 2003, Teagasc and the NMS collaborated on an information booklet called “Good Farming practice and Archaeology” which offered advice to farmers on how to best preserve ancient monuments within different farming systems. In light of the widespread availability of online mapping resources and use of drone photography, it is time perhaps to update this guide to remind farmers and Citizen Archaeologists of the available resources to identify sites and monuments, and of their responsibilities to avoid and report archaeological features on their land.