Lake Enriquillo Water Level History and Implications for future flooding in the Southwestern Dominican Republic
Abstract
Lake Enriquillo is currently located -41m below sea-level, and is the largest lake (~350 km2) in the Caribbean. Lake levels during the past eight years have risen to anomalous highs (from -51m BSL to -41m BSL), flooding villages and displacing their inhabitants. Both the cause of lake level rise and the anticipated future change in lake level remain unclear. Seismic images revealing erosional and depositional sedimentary boundaries in the lake, however, provide insight into historic lake level trends. Here, we integrate seismic images with sediment core samples, and historical photographs to constrain lake level history with time. We used ASTER global digital elevation models combined with single beam data to determine the lake's bathymetry, drainage and surrounding geomorphology. Additionally, we used NOAA and local weather station data to assess the potential role that weather and climate patterns play in lake levels. Although yearly weather conditions play a major role in lake levels, analysis of regional seismic data indicates that tectonics may also play an important role in longer term (century-scale) lake levels. The lake's areal extent and lake level elevation depend not only on the water supply, but also the lake's bathymetry and regional topography that is defined by the Enriquillo-Plantain Garden Fault--a strike-slip fault system that extends throughout the lake. The shallow bathymetry of much of the lake (~ 20%) implies that relatively small changes in the rain pattern cause significant (10 m) changes to lake depth. Over the past thirty years, variations in the lake's areal extent (between 160 km2 to 350km2) and elevation (between -52m BSL to -41m BSL) can be attributed to changes in weather patterns. Preliminary analysis of both core and seismic data confirm that the lake water levels generally mimic wet and dry periods in the region, consistent with recent observations, however, the longer term maximum and minimum extent of Lake Enriquillo water levels, and how these lake levels correlate with paleoclimatic studies remains poorly constrained. Since the lake is quite shallow (<2 m) over a large regional area (~20 %), only moderate (Mw. 7) earthquakes are necessary to change the lake bathymetry profile. Seismic images indicate that the Enriquillo-Plantain Garden fault (EPGF) system actively extends from east to west across the center of the lake. This fault system activates every few hundred years. Preliminary analysis of shallow lake bathymetry near the fault indicates that only slight changes in lake bathymetry via a moderate (Mw 7.0) earthquake along the EPGF may cause potentially significant changes to lake shape and regional bathymetry. Continuing analysis of seismic and coring data, additional up-coming research cruises on the lake next winter, and anticipated age-dates from sediment cores will provide additional insight into the link between lake level variability, climate, and regional tectonics with time.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMNH51C1625W
- Keywords:
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- 1616 GLOBAL CHANGE Climate variability;
- 4321 NATURAL HAZARDS Climate impact;
- 1845 HYDROLOGY Limnology;
- 4302 NATURAL HAZARDS Geological