Thursday 2 july 2015
12:42 - 12:45h at Oceania Foyer (level 0)
Themes: (T) Water resources and hydro informatics (WRHI), (ST) Surface and subsurface flow interactions, Poster pitches
Parallel session: Poster pitches: 11L. WRHI - FlowInteractions
A 19 month investigation has been conducted on the water budget of a meromictic lake in central New York: Fayetteville Green Lake in Green Lakes State Park. The field study has been carried out with a combination of discrete measurements of the stream flow and an innovative subsurface deployment of a pressure logger mooring to record lake level during a complete annual cycle. The hydrological data are interpreted with meteorological information from atmospheric loggers placed next to the lake and from a network of stations provided by the Weather Underground Internet resource. The rich dataset is used as the basis of water budget model to resolve the time series of stream flows, precipitation, groundwater input, and evaporation with the measured lake heights. The density of measurements permits intercomparisons that uncover inconsistencies in the a priori assumptions of time-independent groundwater inflow. The evidence reveals pronounced seasonal changes in groundwater input to the lake that is associated with short-term response to rainfall during the spring, summer and autumn seasons. On the other hand, earlier tracer investigations demonstrated bottom lake water ages exceeding five years, and this points to extended groundwater flow paths. The issues of groundwater flux are significant because the varved bottom sediments of Fayetteville Green Lake are composed mostly of biogenically derived carbonates that are recognized as important archives of regional Holocene climate conditions. The sediment thickness as well as the chemical and isotopic composition reflects a combination of climatic and ecological conditions near the lake surface, which may be associated with groundwater-linked nutrient inputs and is only partially understood.