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. 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 are integrated with field data regarding snail host dynamics and infection rates in order to create liver fluke risk maps at the landscape scale.
A pre-processing chain for SAT and HELI images was developed (WP1). Next, a processing chain to delineate SWBs on HELI images is created (WP2). An object-based image algorithm to semi-automatically capture SWBs on SAT images is established and a method is developed to classify satellite imagery using UAV data as seeds (WP3). A generic tool for SWB dynamics analysis is produced, while also temporal windows for reliable characterization of SWBs on SAT images is detected (WP4). Next, frequent ground visits characterized 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 led to a framework to assess disease transmission risk of F. hepatica (WP6). The results were shared and discussed in regular meetings, reports, (inter)national presentations and publications, while also a project website was created (www.satheli.be) (WP7). Some additional outcomes of the project are 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) and the integration of the risk mapping of SATHELI images into the modelling component of the VECMAP software.