Legacy Land-Use Impacts on Contemporary Stream Network Dynamics

Non-perennial rivers and streams constitute a large portion of the global river network and are expected to increase with climactic variability. They offer important ecological, biogeochemical, and hydrologic functions; these functions are vulnerable to both human development and climate change, thus warranting greater understanding. This research will explore the dynamics of headwater stream intermittency at the Leading Ridge Experimental Watershed (LREW)—a long-term, forested experimental watershed located in the ridge and valley province of central Pennsylvania. LREW is a steep, upland watershed with 98% of its perennial and non-perennial tributaries flowing above the National Hydrography Dataset Plus High-Resolution flowlines. The watershed is highly intermittent and the flowing stream network expands and contracts by an order of magnitude between wet and dry conditions. LREW was logged for charcoal production throughout the 19th century in association with the local iron industry, and recent QL1 LIDAR data reveals that a network of abandoned roads and haul paths remains throughout the watershed. Repeat GPS field surveys conducted under multiple hydrologic conditions have shown that these legacy road features convey and redirect surface flow, further contributing to the intermittent nature of the watershed. A network of stream temperature, intermittency, and conductivity (STIC) sensors have been collecting 15-minute resolution data on stream connectivity and extents at LREW since 2019. A recently expanded STIC network captures the influence of active and legacy road structures. Preliminary results will help advance our understanding of when and how road networks interact with a non-perennial stream network.