Research:

My current research portfolio encompasses themes from remote sensing, carbonate sedimentology, and coral reef ecology:

1- Regional-scale remote sensing of reef architecture: Because metre-scale remote sensing data are computationally intensive to handle, high-resolution mapping projects are traditionally limited to several hundred km2 in extent. Efforts by my lab have produced a workflow capable of manipulating and utilizing high-resolution imagery at regional-scale. In addition, we have developed a rapid-assessment protocol to ground-truth vast and remote reef systems in a very short span of time. Data collected include acoustic current measurements, bathymetry, and sub-bottom profiles, in situ optics, and seafloor video. Using QuickBird satellite data, products of this workflow include >7,000 km2 of seabed habitat maps and spectrally derived bathymetry for the SE Arabian Gulf, and >20,000 km2 for the Red Sea. Using a modified methodology we were able to process >7,000 km2 of airborne hyperspectral CASI flight-lines acquired during a campaign in the Southern Red Sea. These map products facilitate the appraisal of reef architecture at regional-scale but with metre-scale resolution. The upshot is an enhanced understanding of the geological underpinnings to reef morphology and ecological status and function. The major partner for this research is the Khalid bin Sultan Living Oceans Foundation.
 

2- Formative processes in modern reef environments: The structure of today’s reef systems owe much to the underlying form of antecedent topography. This template may arise from tectonic activity, and/or the influence of sub-areal erosion of pre-existing carbonate terraces by chemical weathering. Using landform modelling, my research shows that karstic dissolution delivers surfaces with geometric properties tied to the duration and climate under which the karst developed. Upon inundation by rising sea-level, coral growth accentuates the high points of this terrain and the resulting reef morphology inherits a patterning that can be used to reconstruct the formative processes that shaped the terrain during exposure.
 

3- Geospatial characteristics of modern shoal-water carbonate depositional environments: Modern coral reef environments can serve as analogues to comparable ancient systems, assist facies interpretation and, by examining spatial patterns, help to elucidate depositional dynamics. However, the complexity of reef systems exhibiting spatial heterogeneity on scales of centimetres to kilometres is notoriously difficult to quantify. Recent advances in the capability of Earth observation satellites combined with novel processing algorithms have facilitated the production of accurate three-dimensional reef-scale habitat maps. Satellite imagery is therefore a powerful tool with which to investigate the spatial patterns of coral bioherms, biostromes, and non-frameworks in different environmental and biogeographic settings. Of particular interest is the observation that aspects of the heterogeneity of modern marine carbonate depositional landscapes are predictable through scaling functions that describe the size, shape, and complexity of geobodies. A theme of my research is the analysis of these morphometric properties of the facies mosaic, including rules of facies juxtaposition. Through the investigation of multiple diverse reef sites, I am in the process of examining the influence environmental factors such as exposure, water depth, tidal range, and climate, as well as depositional constraints, such as platform type, have on the geometry of facies patterns. This work is based on the premise that geospatial analysis in modern environments can enhance interpretation of incomplete (i.e. core) records, which will also allow better reconstruction of the entire sedimentary environment in fossil settings, with implications for the identification of potential reservoirs in reefal frameworks or other, spatially similarly operating systems. Funding for this research theme comes from ExxonMobil and Shell Oil.

4- Novel solutions for the detection of subtle and sub-pixel targets in optically complex environments: If it were possible to conduct reef surveys over large areas using fieldwork alone, there would be no need for the use of complex and often unreliable remote sensing technologies. However, fieldwork on coral reefs is inefficient in terms of manpower, time and cost. If the reef is submerged under even a few metres of water, experience has shown that accurate quantification of habitat distribution can only be achieved at a rate of a few hundred metres per person day. Since reef systems cover areas of hundreds if not thousands of square kilometres, it is clear that simple field observation is woefully inadequate to monitor such a valuable resource. To combat this problem, my lab actively researches the use of radiative transfer solutions, edge-detection, and textural analysis, to assist the mapping of submerged targets using multispectral, hyperspectral, and LiDAR datasets. A fusion of these properties greatly increases the accuracy of recognition for features that are either spectrally inseparable from their background (such as corals), else sufficiently submerged to reduce useful radiation to a single long-wavelength (blue) channel.
 

5- LiDAR: Airborne LiDAR (Light Detection And Ranging) for bathymetric and topographic mapping has undergone extensive development in recent decades. The technology is valuable in the coastal realm in that it offers a unique appraisal of seabed terrain from the inter-tidal to depths >60 m. I employ the technology in many aspects of my research and have edited a Special Issue and chaired sessions on the application of LiDAR to coastal mapping. I am involved in the testing and development of airborne LiDAR technologies and am presently collaborating with Dr. John Brock of the USGS for the evaluation of the NASA Experimental Advanced Airborne Research LiDAR (EAARL), and have worked on the evaluation of the Optech airborne LiDAR-CASI fusion instrument.
 

6- Acoustic remote sensing: Although optical sensors deliver unparalleled results in shallow clear water, the limitations of the technology quickly become apparent when depth starts to exceed ~20 metres and/or water clarity is compromised by turbidity. My lab works with numerous vessel-based acoustic systems (QTC, Echoplus & RoxAnn), as well as seafloor penetrating and Doppler profilers.

7- Software development: In collaboration with Kevin Kohler I have developed numerous software solutions to satisfy the requirements of our industrial and Federal partners. The Hybrid Mapping Tool (HMT) is software that addresses the conceptual and methodological problems with automated map generation in both terrestrial and shallow-marine ecosystems. The HMT relies on polygon generation based on the spectral component of an image, in unison with edge-strength and texture. The project was financially supported by the NOS/NOAA Special Projects department. The NERST is a modular software offering image processing functions and shape analysis tuned for application in seabed mapping. The CarbEmu is a proof-of-concept pattern-imitating software capable of emulating morphological rule-sets extracted from carbonate depositional environments.