Inland impacts of atmospheric river and tropical cyclone extremes on nitrate transport and stable isotope measurements

Husic, Admin; Fox, J. F.; Adams, E.; Backus, Jason; Pollock, Erik D.; Ford, William I.; Agouridis, Carmen T.

doi:10.1007/s12665-018-8018-x

Cited by 23 publications

(25 citation statements)

References 70 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The high surface‐subsurface flow path connectivity has been suggested as the primary cause for the deterioration of water quality at the spring (UKCAFE, ). The watershed has been a karst research site led by the Kentucky Geological Survey and the University of Kentucky the past 40 years (Husic, Fox, Agouridis, et al, ; Husic, Fox, Ford, et al, ; Husic et al, ; Paylor & Currens, ; Spangler, ; Taylor, ; Thrailkill et al, ; Zhu et al, ).…”

Section: Methodsmentioning

confidence: 99%

“…Off‐the‐shelf watershed water quality models (e.g., SWAT, HSPF) have been applied to karst nutrient studies with some success (Nikolaidis et al, ; Palanisamy & Workman, ); however, the models tend to be extrapolated beyond their hydrologic structure given the turbulent flow of the karst subsurface requiring empirical augmentation to allow adequate model calibration (Palanisamy & Workman, ). Graphical methods to apportion N loads to fast, intermediate, and slow flow pathways are robust (Fenton et al, ; Husic et al, ; Mellander et al, ), but limited in that they do not explicitly quantify internal N fate nor do they provide forecasting ability. Other karst‐specific nutrient models assume that N is conservative (Mahler & Garner, ; Mudarra et al, ); however, we know that N transformation occurs in karst (Cohen et al, ; Henson et al, ; Katz et al, ; Panno et al, ).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Nitrate Pathways, Processes, and Timing in an Agricultural Karst System: Development and Application of a Numerical Model

Husic

Fox

Adams

et al. 2019

Water Resources Research

Self Cite

View full text Add to dashboard Cite

Nitrogen (N) contamination within agricultural‐karst landscapes and aquifers is widely reported; however, the complex hydrological pathways of karst make N fate difficult to ascertain. We developed a hydrologic and N numerical model for agricultural‐karst, including simulation of soil, epikarst, phreatic, and quick flow pathways as well as biochemical processes such as nitrification, mineralization, and denitrification. We tested the model on four years of nitrate (NO3−) data collected from a phreatic conduit and an overlying surface channel in the Cane Run watershed, Kentucky, USA. Model results indicate that slow to moderate flow pathways (phreatic and epikarst) dominate the N load and account for nearly 90% of downstream NO3− delivery. Further, quick flow pathways dilute NO3− concentrations relative to background aquifer levels. Net denitrification distributed across soil, epikarst, and phreatic water removes approximately 36% of the N inputs to the system at rates comparable to nonkarst systems. Evidence is provided by numerical modeling that NO3− accumulation via evapotranspiration in the soil followed by leaching through the epikarst acts as a control on spring NO3− concentration and loading. Compared to a fluvial‐dominated immature karst system, mature‐karst systems behave as natural detention basins for NO3−, temporarily delaying NO3− delivery to downstream waters and maintaining elevated NO3− concentrations for days to weeks after hydrologic activity ends. This study shows the efficacy of numerical modeling to elucidate complex pathways, processes, and timing of N in karst systems.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nitrate Pathways, Processes, and Timing in an Agricultural Karst System: Development and Application of a Numerical Model

Husic

Fox

Adams

et al. 2019

Water Resources Research

Self Cite

View full text Add to dashboard Cite

show abstract

“…Karst landscapes drain approximately 12% of the earth's surface and serve as a drinking water source for nearly 25% of the Earth's population (Ford & Williams, ; Hartmann, Goldscheider, Wagener, Lange, & Weiler, ). Agricultural karst terrain is highly vulnerable to nutrient leaching, making karst landscapes hotspots for downstream eutrophication (Husic, Fox, Adams, et al, ; Jarvie et al, ; Mellander et al, ). There is increasing recognition that spring and surface water interfaces in karst landscapes are an ecosystem control point for biogeochemical transformations, yet these interfaces remain understudied (Briggs & Hare, ).…”

Section: Introductionmentioning

confidence: 99%

“…Regarding upland dynamics, recent advancements in techniques to quantify karst hydrologic pathways has led to a conceptualization of karst drainage as a series of reservoirs characterized by quick, intermediate, and slow flow pathways (Husic, Fox, Adams, et al, ; Husic, Fox, Ford, et al, ; Rimmer & Hartmann, ). Quickflow in karst watersheds reflects short residence time water originating from sinkholes, swallets, estavelles, and conduits (Pronk, Goldscheider, Zopfi, & Zwahlen, ; White, ).…”

Section: Introductionmentioning

confidence: 99%

“…Slow flow pathways reflect longer residence times and convey water via diffuse Darcian recharge and percolation through small, low‐permeability fissures in the epikarst (Ghasemizadeh et al, ; Mellander et al, ). Quantification of these pathway dynamics is now commonly performed using hydrograph separation techniques on flow time series (e.g., Husic, Fox, Adams, et al, ; Mellander et al, ).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Long‐term assessment of nutrient flow pathway dynamics and in‐stream fate in a temperate karst agroecosystem watershed

Ford

Husic

Fogle

et al. 2019

Hydrological Processes

View full text Add to dashboard Cite

Nutrient dynamics in karst agroecosystems remain poorly understood, in part due to limited long-term nested datasets that can discriminate upland and in-stream processes. We present a 10-year dataset from a karst watershed in the Inner-Bluegrass Region of central Kentucky, consisting of nitrate (nitrate-N [NO 3 − ]), dissolved reactive phosphorus (DRP), total organic carbon (TOC), and total ammoniacal-N (TAN) measurements at nested spring and stream sites as well as flowrate at the watershed outlet. Hydrograph separation techniques were coupled with multiple linear regression and Empirical Mode Decomposition time-series analysis to determine significance of seasonal processes and to generate continuous estimates of nutrient pathway loadings. Further, we used model results of benthic algae growth and decomposition dynamics from a nearby watershed to assess if transient storage in algal biomass could explain differences in spring and downstream watershed nutrient loading. Results highlight statistically significant seasonality for all nutrients at stream sites, but only for NO 3 − at springs with longitudinal variability showing significant decreases occurring from spring to stream sites for NO 3 − and DRP, and significant increases for TOC and TAN. Pathway loading analysis highlighted the importance of slow flow pathways to source approximately 70% of DRP and 80% of NO 3 − . Results for in-stream dynamics suggest that benthic autotroph dynamics can explain summer deviations for TOC, TAN, and DRP but not NO 3 − . Regarding upland dynamics, our findings agree well with existing perceptions in karst for N pathways and upland source seasonality but deviate from perceptions that karst conduits are retentive of P, reflecting the limited buffering capacity of the soil profile and conduit sediments in the Inner-Bluegrass. Regarding in-stream fate, our findings highlighted the significance of seasonally driven nutrient processing in the bedrock-controlled streambed to influence nutrient fluxes at the watershed outlet. Contrary to existing perceptions, we found high N attenuation and an unexplained NO 3 − sink in the bedrock stream, leading us to postulate that floating macrophytes facilitate high rates of denitrification. KEYWORDS bedrock stream, hydrologic pathways, in-stream fate, karst agroecosystem watershed, nutrient loadings, time-series analysis

show abstract

Influence of precipitation event magnitude on baseflow and coastal nitrate export for Prince Edward Island, Canada

Pavlovskii

Jiang

Danielescu

et al. 2023

Hydrological Processes

View full text Add to dashboard Cite

The export of anthropogenic nitrate to coastal waters, which depends on the interplay between many factors such as land use and meteorological forcing, is a rising concern in many regions of the world. The present study investigates the effect of precipitation event magnitude on baseflow and associated groundwaterdriven nitrate export in Prince Edward Island, Canada. Twenty-year time-series of precipitation, stream flow, and groundwater levels across the island were analysed to establish a three-way relationship between precipitation, groundwater level rise, and baseflow increase along a hydrological response pathway in this island setting. The analysis was performed by extracting hydrological responses for groundwater level and baseflow for a selected subset of relatively isolated precipitation events. The results reveal a non-linear relationship between precipitation event magnitude and baseflow change that is also observed for precipitation events associated with hurricanes and post tropical storms. A time-series of streamflow nitrate concentrations during Hurricane Dorian's passage (September 2019) was used to evaluate the relevance of these findings for nitrate export. The data show that baseflow increases after a heavy precipitation event have limited impact on streamflow concentrations, but result in substantial and sustained increase of nitrate export (calculated by multiplying concentration by flow). These observations are consistent with a recharge-induced water table rise leading to increased hydraulic gradients that drive discharge of shallow nitrate-containing groundwater. Due to the similarity of the processes governing groundwater flow to the sea and to streams, the results can be used to gain insights into the impacts of precipitation event magnitude on direct groundwater discharge to coastal waters. On Prince Edward Island, this applies to at least the 13% of the island's surface area that is closer to the ocean than to any stream and likely feeds submarine groundwater discharge pathways.

show abstract

Inland impacts of atmospheric river and tropical cyclone extremes on nitrate transport and stable isotope measurements

Cited by 23 publications

References 70 publications

Nitrate Pathways, Processes, and Timing in an Agricultural Karst System: Development and Application of a Numerical Model

Nitrate Pathways, Processes, and Timing in an Agricultural Karst System: Development and Application of a Numerical Model

Long‐term assessment of nutrient flow pathway dynamics and in‐stream fate in a temperate karst agroecosystem watershed

Influence of precipitation event magnitude on baseflow and coastal nitrate export for Prince Edward Island, Canada

Contact Info

Product

Resources

About