TY - JOUR
T1 - Modeling surface and ground water mixing in the hyporheic zone using MODFLOW and MT3D
AU - Lautz, Laura K.
AU - Siegel, Donald I.
N1 - Funding Information:
The National Science Foundation funded this work. We would like to thank The Wyoming Nature Conservancy for allowing us experimental use of this research site. We would also like to thank the University of Missouri’s Branson Geology Field Camp for help with site instrumentation.
PY - 2006/11
Y1 - 2006/11
N2 - We used a three-dimensional MODFLOW model, paired with MT3D, to simulate hyporheic zones around debris dams and meanders along a semi-arid stream. MT3D simulates both advective transport and sink/source mixing of solutes, in contrast to particle tracking (e.g. MODPATH), which only considers advection. We delineated the hydrochemically active hyporheic zone based on a new definition, specifically as near-stream subsurface zones receiving a minimum of 10% surface water within a 10-day travel time. Modeling results indicate that movement of surface water into the hyporheic zone is predominantly an advective process. We show that debris dams are a key driver of surface water into the subsurface along the experimental reach, causing the largest flux rates of water across the streambed and creating hyporheic zones with up to twice the cross-sectional area of other hyporheic zones. Hyporheic exchange was also found in highly sinuous segments of the experimental reach, but flux rates are lower and the cross-sectional areas of these zones are generally smaller. Our modeling approach simulated surface and ground water mixing in the hyporheic zone, and thus provides numerical approximations that are more comparable to field-based observations of surface-groundwater exchange than standard particle-tracking simulations.
AB - We used a three-dimensional MODFLOW model, paired with MT3D, to simulate hyporheic zones around debris dams and meanders along a semi-arid stream. MT3D simulates both advective transport and sink/source mixing of solutes, in contrast to particle tracking (e.g. MODPATH), which only considers advection. We delineated the hydrochemically active hyporheic zone based on a new definition, specifically as near-stream subsurface zones receiving a minimum of 10% surface water within a 10-day travel time. Modeling results indicate that movement of surface water into the hyporheic zone is predominantly an advective process. We show that debris dams are a key driver of surface water into the subsurface along the experimental reach, causing the largest flux rates of water across the streambed and creating hyporheic zones with up to twice the cross-sectional area of other hyporheic zones. Hyporheic exchange was also found in highly sinuous segments of the experimental reach, but flux rates are lower and the cross-sectional areas of these zones are generally smaller. Our modeling approach simulated surface and ground water mixing in the hyporheic zone, and thus provides numerical approximations that are more comparable to field-based observations of surface-groundwater exchange than standard particle-tracking simulations.
KW - Debris dam
KW - Groundwater flow model
KW - Hyporheic zone
KW - MODFLOW
KW - MT3D
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U2 - 10.1016/j.advwatres.2005.12.003
DO - 10.1016/j.advwatres.2005.12.003
M3 - Article
AN - SCOPUS:33748412624
SN - 0309-1708
VL - 29
SP - 1618
EP - 1633
JO - Advances in Water Resources
JF - Advances in Water Resources
IS - 11
ER -