Monday, 24 January 2011
Washington State Convention Center
Increased concentrations of green house gases (GHG) cause global climate changes that manifests in the Caribbean basin as increased coastal sea surface temperatures (SST), rainy season variability, changes in atmospheric moisture content and cloud cover, among many others. These changes in turn have profound effects at local scales and to the local human, flora, and fauna population. Such is the case of the Enriquillo and Sumatra Lakes basin, located in a highly sensitive ecological region in the border of the Dominican Republic and Haiti, in the Caribbean island of La Hispaniola. This water basin is unique, surrounded by the highest peaks of the region, where most fresh water is produced from the interaction of low level clouds with densely vegetated mountains, resulting in a bowl-like fresh water capture system. The lakes are the largest inland bodies of water in all of the Caribbean Islands. Verbal accounts from local farmers indicate that these water reservoirs are rapidly expanding to the point of penetrating into their farmlands. Remote sensing images from the Landsat satellite gathered between 1980 and 2010 verify these accounts, showing a shrinking and expanding pattern of the lakes since 1986. Surface area of Lake Enriquillo, in the Dominican Republic, was observed to reach minimum values in 2004 (170 km2) as consequence of an extended drought, and then rapidly expanding to its current levels (330 km2), almost doubling in size in less than five years. Lake Sumatra, in Haiti, was observed to grow at similar rates. These rates are the most extreme observed to date since any type of record was first taken in the late 1800's. A closer analysis of the regional hydro-climatic conditions reflects increasing stream flows, dew point (0.66 deg C/decade), trade wind magnitude, and cloud cover. The combined effects of increase inflow to the lakes and decrease evaporation at the lakes' surface might result in the surface area growth observed recently. Projections of the continuous growth of these water reservoirs to 2040 indicate large social 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. The hypothesis that higher SSTs leads to an increase in regional atmospheric moisture content, increasing mountain cloud induced precipitation and inflow to the lakes, which combined with reduced surface evaporation results in changes in the lakes surface areas, is further investigated with the use of the Regional Atmospheric Modeling System (RAMS) coupled with a surface hydrological model.
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