Figure 3. HydroGeoSphere simulated surface water depth (m) and groundwater mean age (log(hour)) for the eight flume scenarios where the logjam permeability, number of logjams, and/or discharge change. The surface water level and connectivity between groundwater and surface water are increased when surface water encounters a logjam. Rising surface water level causes more water to infiltrate into the water-sediment interface in front of the logjam and exfiltrate out behind the logjam. Comparing the scenarios of single logjams (left) and multiple logjams (right), a single jam drives a deep zone of fast exchange, while multiple jams drive shallower but connected and repeated zones of fast exchange.