Aguilar J.,U.S. Department of Agriculture |
Koelliker J.,BAE |
American Society of Agricultural and Biological Engineers Annual International Meeting 2010, ASABE 2010 | Year: 2010
Irrigation water demand in the Great Plains region is lowering groundwater levels, reducing base flow and dewatering vulnerable streams. In western Kansas, groundwater has ceased to supply dependable baseflow to previously perennial streams. The change in baseflow has altered both the natural flow regime of streams and the level of in stream connectivity among pools at low flow. Previous studies have shown that changes occurring in streams have adverse impacts on freshwater ecosystem and fish species distribution. The objective of this study was to document stream flow regime changes for unregulated streams in four geographically distinct regions across Kansas using 60 or more years of daily discharge data. The analysis focused on spatial differences and temporal changes in hydrologic indices relevant to the lotic ecosystem for fourteen unregulated streams. Log Pearson III method was used for computing flow probabilities. The Mann-Kendall test in conjunction with Sen's slope estimator was used for trend analysis. Indicators of Hydrologic Alterations software was used to generate hydrologic indices. Results show a substantial difference in streamflow characteristics between western and eastern regions. Temporally variable indices include median, zero and 1 cfs flow, and timing of low flow. Most streams in western Kansas now have longer and more frequent dry periods. Moreover, the timing of these dry periods could adversely impact essential ecological services and functions. Results of this study are intended to guide decision makers, watershed stakeholders, and environmental conservation advocates in addressing problems and concerns related to stream and river management.
Bae | Date: 2007-02-06
Bae | Date: 2013-11-06
Theater glasses; spectacle frames made of metal and of synthetic material; monocle frames; corrective eyeglasses; eyeglasses; protective eyeglasses; protective eye pieces; sunglasses; swim goggles; snow goggles; ski goggles; goggles for sports; spectacles; cases for spectacles and sunglasses; frames for spectacles and sunglasses; childrens eyeglasses; polarizing spectacles; field-glasses.
Heeren D.M.,University of Nebraska - Lincoln |
Fox G.A.,Oklahoma State University |
Fox A.K.,Private Consultant |
Storm D.E.,BAE |
And 2 more authors.
Hydrological Processes | Year: 2014
Assuming homogeneity in alluvial aquifers is convenient, but limits our ability to accurately predict stream-aquifer interactions. Research is needed on (i) identifying the presence of focused, as opposed to diffuse, groundwater discharge/recharge to streams and (ii) the magnitude and role of large-scale bank and transient storage in alluvial floodplains relative to changes in stream stage. The objective of this research was to document and quantify the effect of stage-dependent aquifer heterogeneity and bank storage relative to changes in stream stage using groundwater flow divergence and direction. Monitoring was performed in alluvial floodplains adjacent to the Barren Fork Creek and Honey Creek in northeastern Oklahoma. Based on results from subsurface electrical resistivity mapping, observation wells were installed in high and low electrical resistivity subsoils. Water levels in the wells were recorded real time using pressure transducers (August to October 2009). Divergence was used to quantify heterogeneity (i.e. variation in hydraulic conductivity, porosity, and/or aquifer thickness), and flow direction was used to assess the potential for large-scale (100 m) bank or transient storage. Areas of localized heterogeneity appeared to act as divergence zones allowing stream water to quickly enter the groundwater system, or as flow convergence zones draining a large groundwater area. Maximum divergence or convergence occurred with maximum rates of change in flow rates or stream stage. Flow directions in the groundwater changed considerably between base and high flows, suggesting that the floodplains acted as large-scale bank storage zones, rapidly storing and releasing water during passage of a storm hydrograph. During storm events at both sites, the average groundwater direction changed by at least 90° from the average groundwater direction during baseflow. Aquifer heterogeneity in floodplains yields hyporheic flows that are more responsive and spatially and temporally complex than would be expected compared to more common assumptions of homogeneity. © 2012 John Wiley & Sons, Ltd.
Fox G.A.,Oklahoma State University |
Heeren D.M.,BAE |
Miller R.B.,BAE |
Mittelstet A.R.,BAE |
Journal of Hydrology | Year: 2011
Streambank seeps commonly originate from localized heterogeneity or preferential flow pathways (PFPs) in riparian floodplains. However, limited field data have been reported on ground water seep flows and solute transport to seeps from PFPs. The objective of this research was to build upon previous floodplain-scale investigations of PFPs by analyzing seep discharge and transport characteristics through a single PFP. An important research question was whether this PFP could be conceptualized as a homogeneous, one-dimensional flow path. Streambank seep discharge measurements were obtained by inducing a hydraulic head in a trench injection system. Also, co-injection of Rhodamine WT (RhWT) and a potassium chloride (KCl) tracer over a 60-min period was used to investigate transport dynamics. Seep discharge and breakthrough curves for electrical conductivity (EC) and RhWT were measured at the streambank using a lateral flow collection device. The breakthrough curves were fit to one-dimensional convective-dispersion equations (CDEs) to inversely estimate solute transport parameters. The PFP from which the seep originated was clean, coarse gravel (6% by mass less than 2.0mm) surrounded by gravel with finer particles (20% by mass less than 2.0mm). Located approximately 2m from the trench, the seep (50cm by 10cm area) required at least 40cm of hydraulic head for flow to emerge at the streambank. At a higher hydraulic head of 125cm, seep discharge peaked at 3.5L/min. This research verified that localized PFPs can result in the rapid transport of water (hydraulic conductivity on the order of 400m/d) and solutes once reaching a sufficient near-bank hydraulic head. A one-dimensional equilibrium CDE was capable of simulating the EC (R2=0.94) and RhWT (R2=0.91) breakthrough curves with minimal RhWT sorption (distribution coefficient, Kd, equal to 0.1cm3/g). Therefore, the PFP could be conceptualized as a one-dimensional, homogenous flow and transport pathway. These results are consistent with previous research observing larger-scale phosphorus transport. © 2011 Elsevier B.V.