International Journal of Applied Earth Observation and Geoinformation Title Assessing Optical Earth Observation Systems for Mapping and Monitoring Temporary Ponds in Arid Areas Author Names and Affiliations

100-150 words) Remote sensing methods for locating and monitoring temporary ponds over large areas in arid lands were tested on a study site in Northern Senegal. Three main results are presented, validated with field data and intended to highlight different spectral, spatial and temporal characteristics of the methods: 1) Among several water indices tested, two Middle InfraRed-based indices (MNDWI – Modified Difference Water Index and NDWI2 – Normalized Difference Water Index) are found to be most efficient; 2) an objective method is given prescribing the necessary sensor spatial resolution in terms of minimal detected pond area; and 3) the potential of multi-temporal MODIS imagery for tracking the filling phases of small ponds is illustrated. These results should assist in epidemiological studies of vectorborne diseases that develop around these ponds, but also more generally for land and water management and preservation of threatened ecosystems in arid areas.