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Synergy of very high resolution satellite and helicopter data for the spatio‐temporal characterisation of small water body dynamics (SATHELI)

Research project SR/00/155 (Research action SR)

Persons :

Description :

Context and objectives

Parasitic diseases are among the most important constraints on animal productivity and welfare. The life cycle of the liver fluke Fasciola hepatica depends on an intermediate snail host (Galba truncatula), which inhabits highly spatial and temporal dynamic small water bodies (SWBs) on pasture land. So far, current liver fluke risk maps only comprise large regions at a low spatial resolution. Mapping SWBs by a multi-scale remote sensing system could substantially improve the temporal and spatial resolution of risk maps, resulting in improved disease management.
The SATHELI project aims at an optimized identification and quantification of SWB dynamics using VHR satellite (SAT) and helicopter (HELI) imagery. Flexible tools and concepts characterizing subtle SWB dynamics in space and time are currently lacking and are the intended purpose of this project. The research focus is the development of a methodology to delineate SWBs and their dynamics on HELI imagery and the creation of an object based image approach steered by HELI-derived SWBs to reliably capture dynamics with SAT images. These SWB dynamics will be integrated with field data regarding snail host dynamics and infection rates in order to create liver fluke risk maps at the landscape scale.

Methodology

In order to reach the project objectives a stepwise methodology will be followed. In a first work package (WP1) we will deal with image acquisition and pre-processing. This includes the development of a sampling protocol for the HELI images, geometric and radiometric correction of both HELI and SAT images and co-registration of both image types. WP2 will focus on the delineation of SWBs on HELI images. In WP3, a segmentation/classification object based algorithm will be developed that will integrate the information derived in WP2. WP4 deals with the quantification of SWB dynamics, including the construction of time series and the quantitative description of SWB changes. Next to all the remote sensing work, SWB typology and disease risk will be identified in WP5. Farms will be monitored for snail abundance and both snail and cattle infection rate. Finally, all the acquired information will lead to the development of a risk map for F. hepatica (WP6). WP 7 will deal with the project management.

Results expected

The anticipated results for WP1 are the development of a pre-processing chain for SAT and HELI images. In WP2, a processing chain to delineate SWBs on HELI images will be created. WP3 will produce an object based image algorithm to capture SWBs on SAT images, using information from the HELI derived SWBs. A generic tool for SWB dynamics analysis will be developed (WP4), while also temporal windows for reliable characterization of SWB dynamics on SAT images will be detected. Next, frequent ground visits will characterize the abundance of snails, the infection status of collected snails and livestock and the dynamics of SWB habitats (WP5). The gathered remote sensing and ground survey information will lead to a framework to assess disease transmission risk of F. hepatica (WP6). The results will be shared and discussed in regular meetings, reports, (inter)national presentations and publications (WP7). Some additional outcomes of the project can be anticipated, such as the incorporation of the spatial sampling of HELI images into the sampling component of the VECMAP software (http://iap.esa.int/vecmap); the integration of the risk mapping of SATHELI images into the modelling component of the VECMAP software; and the creation of a project website (www.satheli.be).

Products and services (if applicable)

As an additional outcome of the SATHELI project, its results could be integrated in the VECMAP software. The spatial sampling of HELI images could be integrated into the sampling component of the VECMAP software, while the risk mapping of SATHELI images could be included into the VECMAP modelling component. VECMAP assists stakeholders in predicting vector-related health risks and in enhancing disease management.

Documentation :