Damming Weakens the Groundwater and Surface Water Exchange and Its Nitrate Removal in Semi-arid Prairie Rivers

Abstract Surface water (SW)-Groundwater (GW) exchange plays a vital role in a prairie aquatic system and the biogeochemical cycling in such a system. Considering the inadequate understanding of damming on SW-GW exchange, a damming prairie river in Southeast Eurasian steppe was chosen to investigate variations of the SW-GW exchange and its influences on the fate of nitrate (NO3-). Both hydraulic and hydrochemical methods were applied to precisely depict the daily and seasonal exchange processes. The upstream and downstream reaches of the dam were observed to be upwelling and downwelling conditions respectively within a hydrologic year. Results obtained from multiple tracer methods and hydraulic method indicate that damming contributed to transfer the stream from the upwelling to the downwelling condition and weaken the SW-GW exchange in the downstream. The patterns of SW-GW exchange modulated the NO3- uptake or production between the SW and the GW. NO3- was mainly removed in the SW-GW exchange zone (SW-GW EZ) of the upwelling segment, while produced in the downwelling segment. Both the removal and production of NO3- were enhanced during snowmelt period, which might be an active period for the SW-GW exchange and NO3- fate. This study underscores the negative effect of damming on the SW-GW exchange and accompanied NO3- removal in prairie river systems.

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Impact of Didymosphenia geminata on hyporheic conditions in trout redds: reason for concern?

Marine and Freshwater Research ◽

10.1071/mf08011 ◽

2008 ◽

Vol 59 (11) ◽

pp. 1028 ◽

Cited By ~ 7

Author(s):

Tobias O. Bickel ◽

Gerard P. Closs

Keyword(s):

New Zealand ◽

Surface Water ◽

Water Exchange ◽

Potential Surface ◽

Didymosphenia Geminata ◽

Exchange Processes ◽

Significant Difference ◽

Hydraulic Conditions ◽

Groundwater Exchange ◽

The Impact

Didymosphenia geminata (Lyngbye) Schmidt (commonly called didymo) is an invasive diatom and of concern to fisheries managers in North America and more recently New Zealand. Didymo grows in thick mats in several river systems on the South Island of New Zealand, often smothering entire river beds. Salmonid eggs, deposited in gravel nests (redds), depend on constant water exchange across the riverbed to provide oxygen-rich water for development. Thick didymo mats might restrict the flow of oxygen-rich water into spawning gravels, resulting in increased egg mortality and reduced trout recruitment. The present study measured hyporheic hydraulic conditions in trout redds with varying didymo cover in the Clutha River catchment, South Island, New Zealand. Didymo cover had no significant effects on several hydraulic variables (flow into the substrate, hydraulic conductivity and hyporheic oxygen concentration). However, there was a significant difference in the potential surface water–groundwater exchange between sites, suggesting some effect of didymo on hydraulic conditions. Considering the limited number of replicates, the impact of didymo on trout redds in the Clutha River cannot be excluded. The present study highlights the need for further research on the possible effects of didymo on important surface water–groundwater exchange processes.

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Water-exchange Processes as Factor of the Energy Fluxes Formation in Ecosystems of the Dnieper Reservoirs

Hydrobiological Journal ◽

10.1615/hydrobj.v46.i5.100 ◽

2010 ◽

Vol 46 (5) ◽

pp. 91-105 ◽

Cited By ~ 2

Author(s):

V. M. Timchenko

Keyword(s):

Water Exchange ◽

Energy Fluxes ◽

Exchange Processes

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Optimal operations for groundwater denitrification of drinking water using heterotrophic biological denitrification process

Water Science & Technology Water Supply ◽

10.2166/ws.2006.060 ◽

2006 ◽

Vol 6 (2) ◽

pp. 125-130

Author(s):

C.-H. Hung ◽

K.-H. Tsai ◽

Y.-K. Su ◽

C.-M. Liang ◽

M.-H. Su ◽

...

Keyword(s):

Drinking Water ◽

Removal Efficiency ◽

Nitrate Removal ◽

Drinking Water Treatment ◽

Nitrate Content ◽

Source Water ◽

Nitrogen Gas ◽

Negative Effect ◽

Denitrification Process ◽

Heterotrophic Denitrification

Due to the extensive application of artificial nitrogen-based fertilizers on land, groundwater from the central part of Taiwan faces problems of increasing concentrations of nitrate, which were measured to be well above 30 mg/L all year round. For meeting the 10 mg/L nitrate standard, optimal operations for a heterotrophic denitrification pilot plant designed for drinking water treatment was investigated. Ethanol and phosphate were added for bacteria growing on anthracite to convert nitrate to nitrogen gas. Results showed that presence of high dissolved oxygen (around 4 mg/L) in the source water did not have a significantly negative effect on nitrogen removal. When operated under a C/N ratio of 1.88, which was recommended in the literature, nitrate removal efficiency was measured to be around 70%, sometimes up to 90%. However, the reactor often underwent severe clogging problems. When operated under C/N ratio of 1.0, denitrification efficiency decreased significantly to 30%. Finally, when operated under C/N ratio of 1.5, the nitrate content of the influent was almost completely reduced at the first one-third part of the bioreactor with an overall removal efficiency of 89–91%. Another advantage for operating with a C/N ratio of 1.5 is that only one-third of the biosolids was produced compared to a C/N value of 1.88.

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The effect of streambed heterogeneity on groundwater-surface water exchange fluxes inferred from temperature time series

Water Resources Research ◽

10.1002/2014wr015769 ◽

2015 ◽

Vol 51 (1) ◽

pp. 198-212 ◽

Cited By ~ 38

Author(s):

Dylan J. Irvine ◽

Roger H. Cranswick ◽

Craig T. Simmons ◽

Margaret A. Shanafield ◽

Laura K. Lautz

Keyword(s):

Time Series ◽

Surface Water ◽

Water Exchange ◽

Temperature Time Series ◽

Temperature Time ◽

Streambed Heterogeneity

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Time Delay Effects on Compactability of Soil-Cement Materials during Proctor Testing

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198121998700 ◽

2021 ◽

pp. 036119812199870

Author(s):

W. Griffin Sullivan ◽

Isaac L. Howard

Keyword(s):

Time Delay ◽

Vital Role ◽

Test Method ◽

Dry Density ◽

Soil Cement ◽

Delay Effects ◽

Proctor Test ◽

Negative Effect ◽

Departments Of Transportation ◽

Cement Mixtures

The Proctor test method, as specified in AASHTO T134 and ASTM D558, continues to play a vital role in design and construction quality control for soil-cement materials. However, neither test method establishes a methodology or standardized protocols to characterize the effects of time delay between cement addition and compaction, also known as compaction delay. Compaction delay has been well documented to have a notably negative effect on compactability, compressive strength, and overall performance of soil-cement materials, but specification tools to address this behavior are not prevalent. This paper aims to demonstrate the extent of compaction delay effects on several soil-cement mixtures used in Mississippi and to present recommended new test method protocols for AASHTO T134 to characterize compaction delay effects. Data presented showed that not all soil-cement mixtures are sensitive to compaction delay, but some mixtures can be very sensitive and lead to a meaningful decrease in specimen dry density. Recommended test method protocols were presented for AASHTO T134 and commentary was presented to provide state Departments of Transportation and other specifying agencies a few examples of how the new compaction delay protocols could be implemented.

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