Richard G Niswonger (Former Employee)
Science and Products
Filter Total Items: 17
No Result Found
Filter Total Items: 63
Mixing effects on nitrogen and oxygen concentrations and the relationship to mean residence time in a hyporheic zone of a riffle-pool sequence Mixing effects on nitrogen and oxygen concentrations and the relationship to mean residence time in a hyporheic zone of a riffle-pool sequence
Flow paths and residence times in the hyporheic zone are known to influence biogeochemical processes such as nitrification and denitrification. The exchange across the sediment-water interface may involve mixing of surface water and groundwater through complex hyporheic flow paths that contribute to highly variable biogeochemically active zones. Despite the recognition of these patterns...
Authors
Ramon C. Naranjo, Richard G. Niswonger, Clinton Davis
Simulation of the Lower Walker River Basin hydrologic system, west-central Nevada, using PRMS and MODFLOW models Simulation of the Lower Walker River Basin hydrologic system, west-central Nevada, using PRMS and MODFLOW models
Walker Lake is a terminal lake in west-central Nevada with almost all outflow occurring through evaporation. Diversions from Walker River since the early 1900s have contributed to a substantial reduction in flow entering Walker Lake. As a result, the lake is receding, and salt concentrations have increased to a level in which Oncorhynchus clarkii henshawi (Lahontan Cutthroat trout) are...
Authors
Kip K. Allander, Richard G. Niswonger, Anne E. Jeton
One-Water Hydrologic Flow Model (MODFLOW-OWHM) One-Water Hydrologic Flow Model (MODFLOW-OWHM)
The One-Water Hydrologic Flow Model (MF-OWHM) is a MODFLOW-based integrated hydrologic flow model (IHM) that is the most complete version, to date, of the MODFLOW family of hydrologic simulators needed for the analysis of a broad range of conjunctive-use issues. Conjunctive use is the combined use of groundwater and surface water. MF-OWHM allows the simulation, analysis, and management...
Authors
Randall T. Hanson, Scott E. Boyce, Wolfgang Schmid, Joseph D. Hughes, Steffen W. Mehl, Stanley A. Leake, Thomas Maddock, Richard G. Niswonger
Surface-groundwater interactions in hard rocks in Sardon Catchment of western Spain: an integrated modeling approach Surface-groundwater interactions in hard rocks in Sardon Catchment of western Spain: an integrated modeling approach
The structural and hydrological complexity of hard rock systems (HRSs) affects dynamics of surface–groundwater interactions. These complexities are not well described or understood by hydrogeologists because simplified analyses typically are used to study HRSs. A transient, integrated hydrologic model (IHM) GSFLOW (Groundwater and Surface water FLOW) was calibrated and post-audited using...
Authors
S.M. Tanvir Hassan, Maciek W. Lubczynski, Richard G. Niswonger, Su Zhongbo
A method for estimating spatially variable seepage and hydrualic conductivity in channels with very mild slopes A method for estimating spatially variable seepage and hydrualic conductivity in channels with very mild slopes
Infiltration along ephemeral channels plays an important role in groundwater recharge in arid regions. A model is presented for estimating spatial variability of seepage due to streambed heterogeneity along channels based on measurements of streamflow-front velocities in initially dry channels. The diffusion-wave approximation to the Saint-Venant equations, coupled with Philip's equation...
Authors
Margaret Shanafield, Richard G. Niswonger, David E. Prudic, Greg Pohll, Richard Susfalk, Sorab Panday
Collaborative modelling and integrated decision support system analysis of a developed terminal lake basin Collaborative modelling and integrated decision support system analysis of a developed terminal lake basin
A terminal lake basin in west-central Nevada, Walker Lake, has undergone drastic change over the past 90 yrs due to upstream water use for agriculture. Decreased inflows to the lake have resulted in 100 km2 decrease in lake surface area and a total loss of fisheries due to salinization. The ecologic health of Walker Lake is of great concern as the lake is a stopover point on the Pacific...
Authors
Richard G. Niswonger, Kip K. Allander, Anne E. Jeton
Science and Products
Filter Total Items: 17
No Result Found
Filter Total Items: 63
Mixing effects on nitrogen and oxygen concentrations and the relationship to mean residence time in a hyporheic zone of a riffle-pool sequence Mixing effects on nitrogen and oxygen concentrations and the relationship to mean residence time in a hyporheic zone of a riffle-pool sequence
Flow paths and residence times in the hyporheic zone are known to influence biogeochemical processes such as nitrification and denitrification. The exchange across the sediment-water interface may involve mixing of surface water and groundwater through complex hyporheic flow paths that contribute to highly variable biogeochemically active zones. Despite the recognition of these patterns...
Authors
Ramon C. Naranjo, Richard G. Niswonger, Clinton Davis
Simulation of the Lower Walker River Basin hydrologic system, west-central Nevada, using PRMS and MODFLOW models Simulation of the Lower Walker River Basin hydrologic system, west-central Nevada, using PRMS and MODFLOW models
Walker Lake is a terminal lake in west-central Nevada with almost all outflow occurring through evaporation. Diversions from Walker River since the early 1900s have contributed to a substantial reduction in flow entering Walker Lake. As a result, the lake is receding, and salt concentrations have increased to a level in which Oncorhynchus clarkii henshawi (Lahontan Cutthroat trout) are...
Authors
Kip K. Allander, Richard G. Niswonger, Anne E. Jeton
One-Water Hydrologic Flow Model (MODFLOW-OWHM) One-Water Hydrologic Flow Model (MODFLOW-OWHM)
The One-Water Hydrologic Flow Model (MF-OWHM) is a MODFLOW-based integrated hydrologic flow model (IHM) that is the most complete version, to date, of the MODFLOW family of hydrologic simulators needed for the analysis of a broad range of conjunctive-use issues. Conjunctive use is the combined use of groundwater and surface water. MF-OWHM allows the simulation, analysis, and management...
Authors
Randall T. Hanson, Scott E. Boyce, Wolfgang Schmid, Joseph D. Hughes, Steffen W. Mehl, Stanley A. Leake, Thomas Maddock, Richard G. Niswonger
Surface-groundwater interactions in hard rocks in Sardon Catchment of western Spain: an integrated modeling approach Surface-groundwater interactions in hard rocks in Sardon Catchment of western Spain: an integrated modeling approach
The structural and hydrological complexity of hard rock systems (HRSs) affects dynamics of surface–groundwater interactions. These complexities are not well described or understood by hydrogeologists because simplified analyses typically are used to study HRSs. A transient, integrated hydrologic model (IHM) GSFLOW (Groundwater and Surface water FLOW) was calibrated and post-audited using...
Authors
S.M. Tanvir Hassan, Maciek W. Lubczynski, Richard G. Niswonger, Su Zhongbo
A method for estimating spatially variable seepage and hydrualic conductivity in channels with very mild slopes A method for estimating spatially variable seepage and hydrualic conductivity in channels with very mild slopes
Infiltration along ephemeral channels plays an important role in groundwater recharge in arid regions. A model is presented for estimating spatial variability of seepage due to streambed heterogeneity along channels based on measurements of streamflow-front velocities in initially dry channels. The diffusion-wave approximation to the Saint-Venant equations, coupled with Philip's equation...
Authors
Margaret Shanafield, Richard G. Niswonger, David E. Prudic, Greg Pohll, Richard Susfalk, Sorab Panday
Collaborative modelling and integrated decision support system analysis of a developed terminal lake basin Collaborative modelling and integrated decision support system analysis of a developed terminal lake basin
A terminal lake basin in west-central Nevada, Walker Lake, has undergone drastic change over the past 90 yrs due to upstream water use for agriculture. Decreased inflows to the lake have resulted in 100 km2 decrease in lake surface area and a total loss of fisheries due to salinization. The ecologic health of Walker Lake is of great concern as the lake is a stopover point on the Pacific...
Authors
Richard G. Niswonger, Kip K. Allander, Anne E. Jeton