Simulating the Stream Temperature Response to Hydrologic and Land Use Alterations

Abstract:

Aquatic ecosystems can be significantly altered by the construction of dams and modification of riparian buffers. The effects of these changes are often reflected in spatial and temporal changes in water temperature. To investigate the water temperature implications of spatially and temporally varying riparian buffers and dam-induced hydrologic alterations, we have developed a modeling system that couples a spatially distributed land surface hydrologic model (DHSVM) with a distributed stream temperature model (RBM). We have tested the modeling system using stream temperature observations from two river basins in the Connecticut River basin, the Ottauquechee and White rivers. The former is characterized by a flow regime that is affected by storage and releases from a man-made reservoir, while the latter is an unregulated watershed with a natural flow regime. In the Ottauquechee River, we compared model simulations with observed temperatures for six scenarios associated with the removal of riparian vegetation and existing impoundments. For the unregulated White River, we compared model simulations with observed stream temperatures for three scenarios characterizing a range of riparian vegetation conditions. Results from the Ottauquechee River indicated significant impacts to water temperatures due to alterations in flow and modifications of riparian buffers. In the case of the White River, we reached similar conclusions regarding the modification of riparian buffers.