I am using water stable isotopes of oxygen-18 and hydrogen-2 to trace waters in the Pemigewasset River Watershed. This research has great potential to provide some unexpected knowledge of the hydrology in the region. My study area is 622 square miles and includes sampling of the Pemigewasset River, the East Branch of the Pemigewasset River, the Lost River/Moosilauke Brook, Hubbard Brook and its tributary Paradise Brook, the Mad River, and the Baker River and its tributary Clay Brook. I am also sampling groundwater wells and rainfall. From the samples I collect I can determine if water in the streams looks more like groundwater or more like rain. In addition to collecting isotope samples, I am also measuring pH, temperature, and conductivity of the streams and groundwater. With these measurements I can determine if groundwater entering the stream can explain changes in pH in the river and if temperature can be used as effectively as isotopes to determine whether or not groundwater is entering the stream. I am using a combination of statistical, graphical, and GIS techniques to analyze my data.
I am also using isotope data from Hubbard Brook Experimental Forest to determine how long water stays in the stream once it enters as rain. I can compare these times to find out if there is a difference based on the size of the watershed. How long does water stay in Paradise Brook compared to Hubbard Brook compared to the Pemigewasset River?
My isotope research will provide a better understanding of the local hydrology, which will aid in improved decision making for the management of the Pemigewasset River and its tributaries. Being able to determine where groundwater enters the stream allows water resource managers to place emphasis on either the direct management of surface water or groundwater. This is important because it will take longer to see the effects of groundwater management than those of surface water management.