Principal Investigator: 
Robert Cook
Keystone College

Natural diel variations in groundwater levels and stream discharge have been described from many settings. In most cases, they are attributable to solar radiation-driven changes in soil moisture and consequently changes in groundwater recharge or runoff. Evapotranspiration occurs primarily in the spring and summer months and produces a daytime drawdown in stored water. Its onset marks the beginning of spring from a hydrologic perspective. Melting of snow and ice, which occurs sporadically throughout fall, winter, and spring in the temperate climate of the study area, introduces water to storage or produces runoff.  Evapotranspiration is of particular interest because it represents a linkage between the biosphere and hydrosphere. The shape of the diel signal produced by evapotranspiration typically exhibits a steep drawdown and a more gradual recovery. The initial perturbation of the groundwater level is modulated by soil moisture content but is generally the inverse of the daily evapotranspiration which takes the form of a sharp-peaked sine curve. Recovery of groundwater levels after drawdown is controlled by the lateral inflow rate of groundwater and the short-term specific yield. Understanding how the evapotranspiration signal is modified as it is transmitted through the groundwater and surface water system has the potential to elucidate watershed characteristics such as the depths, lengths, and velocities of flow paths. A diel signal in a stream is synoptic of watershed characteristics (geology, plant community, soils, topography, stream morphology, soil moisture, etc.). While geology, soils, topography, and stream morphology are generally temporally stable, plant communities and soil moisture on the other hand are dynamic and vulnerable to climate change (as well as invasive species introduction and land use change). The goal of this project is to understand how diel signal characteristics in the headwaters of Buck Hill Creek relate to watershed characteristics and predict how the diel signal characteristics might be affected by changing climate.

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Current or Past research?: 
Current Research

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