Dynamic hydrologic simulation of the Bear Brook Watershed in Maine (BBWM)

Bear Brook Watershed in Maine (BBWM) consists of a pair of research watersh eds, East Bear Brook (EBB) and West Bear Brook (WBB), Years of research and observations have shown both watersheds have high similarity in geographic and hydrologic characteristics; a simple comparison of hydrographs from th ese two watersheds further substantiates this similarity. The Object Watershed Link Simulation (OWLS) model was developed and used to simulate the hydrological processes within the BBWM. The OWLS model is a 3 -dimensional, vector-based, visualized, physically-based distributed waters hed hydrologic model. Simulation results not only provide a close examinati on of hydrologic processes within a watershed, but also dynamically visuali ze the processes of flow separations and Variable Source Areas (VSA), Results from flow separations suggest that surface flow from riparian area is the predominate component for the flood rising limb and that macropore f low from riparian area dominates during the falling limb. Soil matrix flow has little effect during flood period but is a persistent contributor to ba se flow. Results from VSA visualization demonstrate 3-D dynamic changes in surface flow distribution and suggest that downstream riparian areas are th e major contributing area for peak flow. As water chemistry is highly relevant to the flow paths within a watershed, simulations have provided valuable information about source of stream flow and the water migration dynamics to support the study of watershed chemist ry in the BBWM. More specific linkages between the chemistry behavior and t he dynamic hydrologic processes should become the next simulation effort in the watershed study. There are many questions that art critical to watershed chemistry studies l ike: which flow component (surface flow, macropore flow, soil matrix flow) predominates during peak flows? How do the flow components distribute durin g a flood event? How do flow contributions differ between these two watersh eds? Which portion of the watershed contributes the most to the peak flows? These questions remain unknown from previous observations and only can be addressed with a physically-based distributed model.