Wednesday, 25 January 2012
On the Hydro-Meteorological and Social Response of a Tropical Lake Basin, Lakes Enriquillo and Sumatra (La Hispaniola) to Changes in Regional Climate and Land Cover
Hall E (New Orleans Convention Center )
Global climate change manifests in the Caribbean basin as increased coastal sea surface temperatures (SSTs), precipitation anomalies, changes in atmospheric moisture content and cloud cover, among many other effects. These regional changes in turn have a profound impact on the local human, flora, and fauna populations. Such is the case of the Enriquillo water basin, a highly sensitive ecosystem located in the southwestern region of Hispaniola. The major bodies of water in the basin are Lake Enriquillo, in the Dominican Republic, and Lake Sumatra, in Haiti. Verbal accounts from local farmers indicate that these bodies of water are rapidly expanding to the point of penetrating into their farmlands. Remote sensing images, from LANDSAT, gathered between 1980 and 2010 verify these accounts, showing a shrinking and expanding pattern of the lakes since the early 1980s. Surface area of Lake Enriquillo was observed to reach minimum values in 2004 (170 km2) as consequence of an extended drought, and then rapidly expanded to its current levels (>350 km2), more than doubling in size in less than a decade. Lake Sumatra was observed to grow at similar rates, which are the most extreme observed to date since any type of record was first taken in the late 1800's. A land cover change analysis for the southwestern region of Hispaniola shows that deforestation and other types of land changes have not been significant during the observation period to affect the hydrological balance of the area. The land cover analysis also shows an expansion of other bodies of water located outside of the Enriquillo catchment area, further evidence of a regional phenomenon. A detailed analysis of the regional climate conditions over a 30-year period (1980-2010) reflects increasing SSTs (~1 ¢ªC), air temperatures (~0.37 ¢ªC decade-1), dew point (~0.66 ¢ªC decade-1), and precipitation (~30%). This regional climate change might result in the surface area growth observed recently. Size change projections of these water reservoirs to 2040 indicate large social, economical, and ecological impacts, making this work one of the first and most important climate impact studies due to global warming in the region of interest. Furthermore, if the recent expansion of the lakes continues as projected, local governments might be forced to issue evacuations, prompting one of the first cases of environmental refugees not forced by an extreme event (e.g., hurricane, tsunami, earthquake). Given the importance of the problem at hand, the hypothesis of lakes expansion in the Enriquillo basin as a regional response to global climate change (i.e., global warming) is further investigated with the use of a regional atmospheric modeling system, complemented by the vegetation maps generated for the land cover change study and coupled with a water balance model over the watershed.
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