THE INFLUENCE OF THE GROUNDWATER TABLE ELEVATION ON BEACH SUBSURFACE TEMPERATURES AT BALD HEAD ISLAND NC

We determined the potential effect of beach water table elevation on ground temperatures at sea turtle nesting depths (0-0.5 m) on a narrow beach at Bald Head Island, NC. Subsurface thermal variations in the 2 wells used in the study reflected progressively decreasing and lagged versions of surface temperatures. Long-term averages (weekly) of subsurface temperatures versus water table elevation showed an inverse relationship where temperatures are generally higher with a low water table and vice versa. Temperature variance was reduced at depth following the relationship T_variance = 28.132e ^{-1.095(depth)} in the summer months. Our initial field results suggest that the position of the water table relative to the ground surface can influence subsurface temperatures. Data analysis at different time scales in conjunction with heat transport modeling will be conducted to better quantify subsurface temperature effects.