Rob O'Hara

Dr. Rob O'Hara

orcid

Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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25 March 2022 in Remote Sensing Applications: Society and Environment
Verified
Journal Article
Open access
MSMohamed Saadeldin
Mohamed Saadeldin
RORob O'Hara
Rob O'Hara
JZJesko Zimmermann
Jesko Zimmermann
BNBrian Mac Namee
Brian Mac Namee
SGStuart Green
Stuart Green

7 January 2022 in Geocarto International
Verified
Journal Article
Closed access
RORob O'Hara
Rob O'Hara
JZJesko Zimmermann
Jesko Zimmermann
SGStuart Green
Stuart Green
Rotational grazing in paddocks is a strong indicator of intensive grassland management. Uncertainty in the extent of grassland management intensity is a reported source of uncertainty in greenhouse gas budgeting. This article outlines a method of detecting paddock locations in Sentinel 2 satellite imagery using a statistical multimodality test. The test was compared to three machine learning algorithms (support vector machine, random forest and extreme gradient boosting). Photographic records of the Eurostat 2018 LUCAS survey were used as ground truth data to confirm the presence or absence of paddocks. The multimodality test achieved an overall accuracy of 88.4% versus the best machine learning accuracy of 82.4%. The test was also used to map paddock occurrence at a regional scale in the Republic of Ireland. Overall map accuracy was 85.7% versus validation data. The test can be applied in temperate grasslands with pre-mapped field boundaries where rotational grazing is practiced.

1 July 2020 in Journal of Applied Remote Sensing
Verified
Journal Article
Closed access
PDF file
RORob O'Hara
Rob O'Hara
SGStuart Green
Stuart Green
TMTimothy McCarthy
Timothy McCarthy
CCConor Cahalane
Conor Cahalane
OFOwen Fenton
Owen Fenton
PTPat Tuohy
Pat Tuohy
<!-- *** Custom HTML *** --> In many areas of the globe, the installation of artificial drains on naturally poorly drained soils is a necessary part of farm management. Identifying the location of artificially drained areas is an important step in achieving environmentally sustainable agricultural production. However, in many regions, data on the presence or the distribution of artificial drainage systems are rare. We outline an approach to identify artificially drained soils using Earth observation (EO) satellite imagery and digital elevation data. The method exploits the contrasting phenology of grass during a peak growth stage to identify artificially drained and undrained soils. Two machine-learning techniques, support vector machine and random forest, were tested. Classification accuracy up to 91% was achieved using photointerpreted accuracy points using higher resolution satellite imagery. Additional investigations would be required to establish whether the drained conditions identified were a result of artificial drainage or from naturally well-drained soils occurring within larger soil units. Herein, the Republic of Ireland is used as a test case. Based on our findings, the area of artificially drained grassland within the study area could be revised upward, with 44% (or ∼345 , 000 ha) of pasture currently classed as “poorly drained” identified as “artificially drained.” At one location, a change in the modeled drainage condition at field level was demonstrated following drain installation. The presented method demonstrates the ability of EO satellites to quickly and accurately map field drainage status at farm management scales over a wide area. This has the potential to improve management decisions at local scales, but also has implications in terms of national policy development and regulation in areas such as water quality and climate change mitigation.