Submitted to: Hydrology and Earth System Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/2012
Publication Date: 7/3/2012
Citation: Alkhaier, F., Z. Su, and G.N. Flerchinger. 2012. Reconnoitering the effect of shallow groundwater on land surface temperature and surface energy balance using MODIS and SEBS. Hydrologic and Earth System Sciences. 16:1833-1844. Interpretive Summary: Utilizing satellite measurements of surface temperature in to delineate the areal extent of shallow groundwater can be of great value in supporting groundwater flow models, improving management of irrigation systems, and integrating shallow groundwater influence on surface energy balance in land surface models and climate studies. We investigated the ability of MODIS satellite observations of surface temperature coupled with calculation of surface energy fluxes computed using the Surface Energy Balance System (SEBS) for detecting shallow groundwater in an area within Al-Balikh River basin in northern Syria. The presence and influence of shallow groundwater on surface temperature and surface energy fluxes was clearly delineated under suitable atmospheric conditions. Mapping shallow groundwater effect on surface energy fluxes using remote sensing will be of great help in assessing the interactions of groundwater dynamics, land surface processes, climate and the atmosphere.
Technical Abstract: The possibility of observing shallow groundwater depth and areal extent using satellite measurements can support groundwater models and vast irrigation systems management. Besides, these measurements help to integrate groundwater effects on surface energy balance within land surface models and climate studies. To inspect the MODIS capacity of detecting shallow groundwater effect on land surface temperature and surface energy balance in an area within Al-Balikh River basin in northern Syria, we investigated the interrelationship between in-situ measured water table depths and land surface temperatures of MODIS. Further, we used the Surface Energy Balance System (SEBS) to calculate surface energy fluxes, evaporative fraction and daily evaporation, and inspected their relationships with water table depths. In agreement with the findings of a companion paper (Alkhaier et al., 2011), we found that daytime temperature increased and nighttime temperature decreased with increasing water table depth. Where water table depth increased, net radiation, latent and ground heat fluxes, evaporative fraction and daily evaporation decreased, while sensible heat flux increased. The clear observed relationships resulted from meeting both conditions concluded in the companion paper, i.e. high potential evaporation and big contrast in air temperature. Moreover, the prevailing conditions in this study area helped SEBS producing accurate estimates. We conclude that MODIS is suitable for shallow groundwater effect detection since it has proper imaging times and appropriate sensor accuracy; nevertheless, its coarse spatial resolution is disadvantageous.