@article{england_james_chutko_pyrce_yao_2019, title={Hydrologic and water isotope characterization of a regulated Canadian Shield river basin}, volume={33}, ISSN={0885-6087}, url={http://dx.doi.org/10.1002/hyp.13371}, DOI={10.1002/hyp.13371}, abstractNote={Abstract}, number={6}, journal={Hydrological Processes}, publisher={Wiley}, author={England, Nancy and James, April L. and Chutko, Krystopher J. and Pyrce, Richard S. and Yao, Huaxia}, year={2019}, month={Jan}, pages={905–919} }
 @article{wachowiak_walters_kovacs_wachowiak-smolíková_james_2017, title={Visual analytics and remote sensing imagery to support community-based research for precision agriculture in emerging areas}, volume={143}, ISSN={0168-1699}, url={http://dx.doi.org/10.1016/j.compag.2017.09.035}, DOI={10.1016/j.compag.2017.09.035}, abstractNote={Agriculture in northern Ontario, Canada, has not yet reached the level of development of the southern regions of the province. In spite of the increasing desirability of the former region for agricultural expansion, northern agricultural producers – as well as other producers in “emerging” areas – have less access to information and decision support services relative to more established agricultural regions. At the same time, geographic information systems (GIS) are now being integrated into precision agriculture to assess field variability, to ensure optimal use of information, to maximize output, and to increase efficiency. To address this trend, a community-based research initiative based on an interactive web-based information visualization and GIS decision support system has been deployed with the aim of providing northern Ontario producers with access to the data they need to make the best possible decisions concerning their crops. This system employs citizen science and community-based participatory research to build a mutually beneficial partnership between agricultural producers, researchers, and other community stakeholders.}, journal={Computers and Electronics in Agriculture}, publisher={Elsevier BV}, author={Wachowiak, Mark P. and Walters, Daniel F. and Kovacs, John M. and Wachowiak-Smolíková, Renata and James, April L.}, year={2017}, month={Dec}, pages={149–164} }
 @article{wachowiak_james_wachowiak-smolíková_walters_chutko_rusak_2017, title={Visual analytics of high-frequency lake monitoring data}, volume={5}, ISSN={2364-415X 2364-4168}, url={http://dx.doi.org/10.1007/s41060-017-0072-z}, DOI={10.1007/s41060-017-0072-z}, number={2-3}, journal={International Journal of Data Science and Analytics}, publisher={Springer Science and Business Media LLC}, author={Wachowiak, Mark P. and James, April L. and Wachowiak-Smolíková, Renata and Walters, Dan F. and Chutko, Krystopher J. and Rusak, James A.}, year={2017}, month={Sep}, pages={99–110} }
 @article{birch_emanuel_james_nichols_2016, title={Hydrologic Impacts of Municipal Wastewater Irrigation to a Temperate Forest Watershed}, volume={45}, ISSN={0047-2425}, url={http://dx.doi.org/10.2134/jeq2015.11.0577}, DOI={10.2134/jeq2015.11.0577}, abstractNote={Land application of municipal wastewater to managed forests is an important treatment and water reuse technology used globally, but the hydrological processes of these systems are not well characterized for temperate areas with annual rainfall of 1200 mm or greater. This study evaluated the impact of municipal wastewater irrigation to the local water balance at a 3000‐ha land application facility where secondary‐treated wastewater is land applied to a mixed hardwood–pine forest over 900 ha. Stable isotopes of hydrogen (2H) and oxygen (18O), chloride concentrations, and specific conductance were used in combination with hydrometric measurements to estimate the wastewater composition in groundwater, surface water, and at the watershed outlet during dry and wet seasonal periods and during one large rainfall event. Wastewater and water bodies receiving irrigation were found to have significantly higher δ2H, δ18O, specific conductance, and chloride concentrations. Using these tracers, a two‐component, three‐end member geochemical mixing model estimated mean wastewater compositions in the surficial aquifer receiving irrigation from 47 to 73%. Surface water onsite was found to reflect the high wastewater composition in groundwater. Land‐applied wastewater contributed an estimated 24% of total streamflow, with the highest wastewater compositions in surface water observed during major storm events and at low‐flow conditions. Groundwater and surface water within the watershed were found to have proportionally higher wastewater compositions than expected based on the proportion of irrigation to rainfall received by these areas.}, number={4}, journal={Journal of Environmental Quality}, publisher={Wiley}, author={Birch, Andrew L. and Emanuel, Ryan E. and James, April L. and Nichols, Elizabeth Guthrie}, year={2016}, month={Jul}, pages={1303–1312} }
 @article{zhang_chen_yao_james_2016, title={Moving SWAT model calibration and uncertainty analysis to an enterprise Hadoop-based cloud}, volume={84}, ISSN={1364-8152}, url={http://dx.doi.org/10.1016/j.envsoft.2016.06.024}, DOI={10.1016/j.envsoft.2016.06.024}, abstractNote={With enhanced availability of high spatial resolution data, hydrologic models such as the Soil and Water Assessment Tool (SWAT) are increasingly used to investigate effects of management activities and climate change on water availability and quality. The advantages come at a price of greater computational demand and run time. This becomes challenging to model calibration and uncertainty analysis as these routines involve a large number of model runs. For efficient modelling, a cloud-based Calibration and Uncertainty analysis Tool for SWAT (CUT-SWAT) was implemented using Hadoop, an open source cloud platform, and the Generalized Likelihood Uncertainty Estimation method. Test results on an enterprise cloud showed that CUT-SWAT can significantly speedup the calibration and uncertainty analysis processes with a speedup of 21.7–26.6 depending on model complexity and provides a flexible and fault-tolerant model execution environment (it can gracefully and automatically handle partial failure), thus would be an ideal method to solve computational demand problems in hydrological modelling.}, journal={Environmental Modelling & Software}, publisher={Elsevier BV}, author={Zhang, Dejian and Chen, Xingwei and Yao, Huaxia and James, April}, year={2016}, month={Oct}, pages={140–148} }
 @article{lin_chen_yao_chen_liu_gao_james_2015, title={Analyses of landuse change impacts on catchment runoff using different time indicators based on SWAT model}, volume={58}, ISSN={1470-160X}, url={http://dx.doi.org/10.1016/j.ecolind.2015.05.031}, DOI={10.1016/j.ecolind.2015.05.031}, abstractNote={Previous researches mainly focused on the runoff responses to landuse change based on annual, seasonal or monthly time scales, there are few studies based on daily scale. We conducted a comprehensive investigation into runoff responses on the daily scale as well as annual and monthly time scales using SWAT, and compared the impacts of time scales with different time indicators quantitatively. Jinjiang, a coastal catchment of southeast China with a humid sub-tropical climate, was used for simulations. A calibrated SWAT model produced satisfactory reproduction of annual, monthly and daily runoff processes over a nine-year (2002–2010) period at three gauging stations. Runoff was then simulated and compared using the same meteorological input but two different landuse scenarios (1985 and 2006, with reduced forest and increased cropland and urbanized area). The results showed varying change in runoff among three time scales and three catchments. The annual runoff had the smallest increase between two scenarios, monthly runoffs had medium rates (increasing in all months except October–November), and daily runoff had the largest rates with the increase in flood peaks but decrease in drought flows, because of the variable influence on interception/evapotranspiration loss, percolation and antecedent soil water storage. Indicators of different time scales (annual runoff, monthly runoff, maximum 1-day and 5-day flood runoff, minimum 1-day and 7-day runoff) proved appropriate for analysing landuse change impacts.}, journal={Ecological Indicators}, publisher={Elsevier BV}, author={Lin, Bingqing and Chen, Xingwei and Yao, Huaxia and Chen, Ying and Liu, Meibing and Gao, Lu and James, April}, year={2015}, month={Nov}, pages={55–63} }
 @article{mountain_james_chutko_2015, title={Groundwater and surface water influences on streamflow in a mesoscale Precambrian Shield catchment}, volume={29}, ISSN={0885-6087}, url={http://dx.doi.org/10.1002/hyp.10590}, DOI={10.1002/hyp.10590}, abstractNote={Abstract}, number={18}, journal={Hydrological Processes}, publisher={Wiley}, author={Mountain, Nathan and James, April Lynda and Chutko, Krystopher}, year={2015}, month={Jul}, pages={3941–3953} }
 @article{fu_james_yao_2015, title={Investigations of uncertainty in SWAT hydrologic simulations: a case study of a Canadian Shield catchment}, volume={29}, ISSN={0885-6087}, url={http://dx.doi.org/10.1002/hyp.10477}, DOI={10.1002/hyp.10477}, abstractNote={Abstract}, number={18}, journal={Hydrological Processes}, publisher={Wiley}, author={Fu, Congsheng and James, April L. and Yao, Huaxia}, year={2015}, month={Apr}, pages={4000–4017} }
 @article{steelman_nichols_james_bradford_ebersöhn_scherman_omidire_bunn_twine_mchale_2015, title={Practicing the science of sustainability: the challenges of transdisciplinarity in a developing world context}, volume={10}, ISSN={1862-4065 1862-4057}, url={http://dx.doi.org/10.1007/s11625-015-0334-4}, DOI={10.1007/s11625-015-0334-4}, number={4}, journal={Sustainability Science}, publisher={Springer Science and Business Media LLC}, author={Steelman, Toddi and Nichols, Elizabeth Guthrie and James, April and Bradford, Lori and Ebersöhn, Liesel and Scherman, Vanessa and Omidire, Funke and Bunn, David N. and Twine, Wayne and McHale, Melissa R.}, year={2015}, month={Sep}, pages={581–599} }
 @article{yao_james_mcconnell_turnbull_field_somers_2015, title={Relative contributions of stream concentration, stream discharge and shoreline load to base cation trends in Red Chalk and Harp lakes, south-central Ontario, Canada}, volume={30}, ISSN={0885-6087}, url={http://dx.doi.org/10.1002/hyp.10627}, DOI={10.1002/hyp.10627}, abstractNote={We evaluated the importance and contributions of changes in stream base cation concentration, stream discharge and lake shoreline load to changes in base cation concentrations in two small inland lakes in south‐central Ontario. The shoreline load from ungauged drainage areas was calculated with a mass balance equation. An evaluation method based on the partial Mann–Kendall test quantified the relative contributions of these three explanatory drivers to the observed trends in lake concentration of Ca, K, Mg and Na. Over a 29‐year period (1978–2006) at Red Chalk and Harp lakes, declines in stream concentration and discharge were correlated with the declines in lake concentrations of all base cations (except for Na in Harp Lake), with contributions of 21–81% from stream concentration and 12–58% from discharge, whereas the shoreline load had little contribution to observed trends. The observed unusual increase in Na concentration at Harp Lake was correlated with the increase in stream Na concentration and additional load from road salts, with the shoreline load contributing a substantial 37%. These results may be applicable to numerous inland lakes with similar site conditions, including lakes found on the Canadian Shield. Copyright © 2015 John Wiley & Sons, Ltd.}, number={6}, journal={Hydrological Processes}, publisher={Wiley}, author={Yao, Huaxia and James, April and McConnell, Christopher and Turnbull, Brian and Field, Timothy and Somers, Keith M.}, year={2015}, month={Sep}, pages={858–872} }
 @article{dech_mayhew-hammond_james_pokharel_2014, title={Modeling Canada yew (Taxus canadensis Marsh.) distribution and abundance in the boreal forest of northeastern Ontario, Canada}, volume={36}, ISSN={1470-160X}, url={http://dx.doi.org/10.1016/j.ecolind.2013.06.017}, DOI={10.1016/j.ecolind.2013.06.017}, abstractNote={a b s t r a c t Canada yew (Taxus canadensis Marsh.) is a gymnosperm shrub that occurs in the understorey of conifer- ous and deciduous forests throughout the northeastern United States and southeastern Canada. Canada yew foliage contains high concentrations of paclitaxel and other taxanes, which have proven effective in treating many forms of cancer. A major challenge to the sustainable management of wild Canada yew harvest is the lack of a spatial inventory of the resource. The objective of this study was to develop a spatial model to predict the distribution and abundance of Canada yew populations in a forest landscape representative of the boreal forest region of Ontario, Canada. The study was conducted in the Romeo Mallete Forest (RMF) located on the southern edge of the boreal forest west of Timmins, Ontario. Abun- dance of Canada yew populations was assessed in 140 circular sample plots (5541 m 2 ), established at locations throughout the RMF. Canada yew abundance in each sample plot was estimated as the mean percent cover of three randomly located 100 m2 subplots. Predictor variables were extracted from the Forest Resources Inventory (FRI) of the RMF, and from layers derived from remote sensing data covering the study area. A combination of classification and regression trees with Random Forests analysis was used to develop a classification model for FRI polygons based on patterns of Canada yew abundance, and assess the performance of the model. The classification error rate on the presence/absence model was approximately 21%, and the root mean squared error on the best continuous cover model was 9.1%. In all analyses, the most important classification node was based on percent basal area of the shade-tolerant late successional species Balsam Fir (Abies balsamea (L.) Mill), which suggests that patterns of Canada yew abundance are driven largely by time since disturbance.}, journal={Ecological Indicators}, publisher={Elsevier BV}, author={Dech, Jeffery P. and Mayhew-Hammond, Shawn and James, April L. and Pokharel, Bharat}, year={2014}, month={Jan}, pages={48–58} }
 @article{fu_james_yao_2014, title={SWAT-CS: Revision and testing of SWAT for Canadian Shield catchments}, volume={511}, ISSN={0022-1694}, url={http://dx.doi.org/10.1016/j.jhydrol.2014.02.023}, DOI={10.1016/j.jhydrol.2014.02.023}, abstractNote={Canadian Shield catchments are under increasing pressure from various types of development (e.g., mining and increased cottagers) and changing climate. Within the southern part of the Canadian Shield, catchments are generally characterized by shallow forested soils with high infiltration rates and low bedrock infiltration, generating little overland flow, and macropore and subsurface flow are important streamflow generation processes. Large numbers of wetlands and lakes are also key physiographic features, and snow-processes are critical to catchment modeling in this climate. We have revised the existing, publicly available SWAT (version 2009.10.1 Beta 3) to create SWAT-CS, a version representing hydrological processes dominating Canadian Shield catchments, where forest extends over Precambrian Shield bedrock. Prior to this study, very few studies applying SWAT to Canadian Shield catchments exist (we have found three). We tested SWAT-CS using the Harp Lake catchment dataset, an Ontario Ministry of Environment research station located in south-central Ontario. Simulations were evaluated against 30 years of observational data, including streamflow from six headwater sub-catchments (0.1–1.9 km2), outflow from Harp Lake (5.4 km2) and five years of weekly snow water equivalent (SWE). The best Nash–Sutcliffe efficiency (NSE) results for daily streamflow calibration, daily streamflow validation, and SWE were 0.60, 0.65, and 0.87, respectively, for sub-catchment HP4 (with detailed land use and soil data). For this range of catchment scales, land cover and soil properties were found to be transferable across sub-catchments with similar physiographic features, namely streamflow from the remaining five sub-catchments could be modeled well using sub-catchment HP4 parameterization. The Harp Lake outflow was well modeled using the existing reservoir-based target release method, generating NSEs of 0.72 and 0.67 for calibration and verification periods respectively. With significant changes to the infiltration module (introducing macropore flow and reduced bedrock percolation), more than 90% of interflow was generated close to the soil–bedrock interface and the contribution of groundwater flow to total runoff was reduced to small amounts, consistent with hydrological process understanding in this terrain. These two changes also allowed for a positive linear relationship between NSE of SWE and Q, whereas prior to these changes there was a negative relationship. With these key revisions to the infiltration and bedrock percolations modules, it is concluded that SWAT-CS can reasonably capture key hydrological processes within Canadian Shield catchments. Further testing will examine water quality modeling and larger-scale applications.}, journal={Journal of Hydrology}, publisher={Elsevier BV}, author={Fu, Congsheng and James, April L. and Yao, Huaxia}, year={2014}, month={Apr}, pages={719–735} }
 @article{dreps_james_sun_boggs_2014, title={Water Balances of Two Piedmont Headwater Catchments: Implications for Regional Hydrologic Landscape Classification}, volume={50}, ISSN={1093-474X}, url={http://dx.doi.org/10.1111/jawr.12173}, DOI={10.1111/jawr.12173}, abstractNote={Abstract}, number={4}, journal={JAWRA Journal of the American Water Resources Association}, publisher={Wiley}, author={Dreps, C. and James, A.L. and Sun, G. and Boggs, J.}, year={2014}, month={Apr}, pages={1063–1079} }
 @article{edwards_amatya_williams_hitchcock_james_2013, title={Flow Characterization in the Santee Cave System in the Chapel Branch Creek Watershed, Upper Coastal Plain of South Carolina, USA}, volume={75}, ISSN={1090-6924}, url={http://dx.doi.org/10.4311/2011es0262}, DOI={10.4311/2011es0262}, abstractNote={Karst watersheds possess both diffuse and conduit flow and varying degrees of connectivity between surface and groundwater over spatial scales that result in complex hydrology and contaminant transport processes. The flow regime and surface- groundwater connection must be properly identified and characterized to improve management in karst watersheds with impaired water bodies, such as the Chapel Branch Creek (CBC), South Carolina watershed, which has a long-term sampling station presently listed on an EPA 303(d) list for phosphorous, pH, and nitrogen. Water from the carbonate limestone aquifer of the Santee Cave system and spring seeps in the CBC watershed were monitored to characterize dominant flow type and surface-groundwater connection by measuring dissolved calcium and magnesium, total suspended solids, volatile suspended solids, alkalinity, pH, specific conductance, and stable isotopes (d 18 O, d 2 H). These measurements indicated that the conduit flow to Santee Cave spring was recharged predominantly from diffuse flow, with a slow response of surface water infiltration to the conduit. Qualitative dye traces and stage elevation at Santee Cave spring and the adjacent Lake Marion (equal to the elevation of the flooded portion of CBC) also indicated a relation between fluctuating base level of the CBC reservoir-like embayment and elevation of the Santee Limestone karst aquifer at the spring. Methods described herein to characterize the flow type and surface-groundwater connection in the Santee Cave system can be applied not only to watershed management in the Chapel Branch Creek watershed, but also to the greater region where this carbonate limestone aquifer exists.}, number={2}, journal={Journal of Cave and Karst Studies}, publisher={National Speleological Society}, author={Edwards, Amy and Amatya, Devendra and Williams, Thomas and Hitchcock, Daniel and James, April}, year={2013}, month={Aug}, pages={136–145} }
 @article{johnson_shear_james_2013, title={Novel ways to assess forested wetland restoration in North Carolina using ecohydrological patterns from reference sites}, volume={7}, ISSN={1936-0584}, url={http://dx.doi.org/10.1002/eco.1390}, DOI={10.1002/eco.1390}, abstractNote={ABSTRACT}, number={2}, journal={Ecohydrology}, publisher={Wiley}, author={Johnson, Yari Ben and Shear, Theodore Henry and James, April Lynda}, year={2013}, month={May}, pages={692–702} }
 @article{inkiläinen_mchale_blank_james_nikinmaa_2013, title={The role of the residential urban forest in regulating throughfall: A case study in Raleigh, North Carolina, USA}, volume={119}, ISSN={0169-2046}, url={http://dx.doi.org/10.1016/j.landurbplan.2013.07.002}, DOI={10.1016/j.landurbplan.2013.07.002}, abstractNote={Overwhelming stormwater volumes, associated with deteriorating water quality and severe flooding in urbanizing cities, have become a great environmental and financial concern globally. Urban forests are capable of reducing the amount of stormwater runoff, in part, by regulating throughfall via canopy rainfall interception; however, the lack of stand-scale studies of urban throughfall hinders realistic estimates of the benefits of urban vegetation for stormwater regulation. Furthermore, urban forest characteristics that may be influencing rainfall interception are difficult to establish as these environments are extremely heterogeneous and managed, to a large extent, by private residents with varying landscape preferences. To quantify the amount of rainfall interception by vegetation in a residential urban forest we measured throughfall in Raleigh, NC, USA between July and November 2010. We analyzed 16 residential yards with varying vegetation structure to evaluate the relative importance of different descriptive measures of vegetation in influencing throughfall in an urban watershed. Throughfall comprised 78.1–88.9% of gross precipitation, indicating 9.1–21.4% rainfall interception. Canopy cover (p < 0.0001) and coniferous trees (p = 0.017) were the most influential vegetation variables explaining throughfall whereas variables such as leaf area index were not found significant in our models. Throughfall and vegetation characteristics varied significantly among yards (p < 0.0001), between front and back yards (p < 0.0001), and between rented and privately-owned yards (p = 0.001), suggesting a potentially significant role in stormwater regulation for urban residents.}, journal={Landscape and Urban Planning}, publisher={Elsevier BV}, author={Inkiläinen, Elina N.M. and McHale, Melissa R. and Blank, Gary B. and James, April L. and Nikinmaa, Eero}, year={2013}, month={Nov}, pages={91–103} }
 @article{fu_james_wachowiak_2012, title={Analyzing the combined influence of solar activity and El Niño on streamflow across southern Canada}, volume={48}, ISSN={0043-1397}, url={http://dx.doi.org/10.1029/2011wr011507}, DOI={10.1029/2011wr011507}, abstractNote={It is well known that the spatial and temporal patterns in streamflow can be correlated with many teleconnections, e.g., solar activity and climatic phenomena such as El Niño. However, fewer studies have attempted to analyze both the influence of solar activity and large scale climatic phenomena on natural processes, particularly hydrological processes. In this study we examine long term records of solar activity and El Niño for their combined influence on streamflow across southern Canada. Data used in the analysis include sunspot number, sea surface temperature anomaly in Niño region 3.4, and annual mean streamflow from 50 Canadian Reference Hydrometric Basin Network (RHBN) stations with record lengths ≥50 years (14 of them ≥90 years). Analysis is performed using Fourier spectrum analysis (FSA), continuous wavelet transform (CWT), and cross wavelet transform coherence analysis (WTC). Results of FSA show that for almost all the 14 RHBN stations with record lengths of ≥90 years, streamflow exhibits periodicities of approximately 11 and 22 years (which is in accordance with solar activity), as well as shorter term periodicities consistent with El Niño (2–7 years). WTC analysis confirms the correlation between these periodicities (2–7 years, 11 years, 22 years) in streamflow with solar activity and El Niño records. Both solar activity and El Niño's influences on annual mean streamflow in 18–32 year bands are common, while the influence of El Nino is more extensive in the 2–7 and ∼11 year bands. Through examination of correlations between solar activity and streamflow, El Niño and streamflow, and finally El Niño and solar activity, WTC analysis has identified that solar activity affects El Niño first, and this influence is then transferred by El Niño to streamflow. This study expands on earlier efforts examining linkages between El Niño and streamflow across southern Canada to an examination of linkages between solar activity, El Niño, and streamflow.}, number={5}, journal={Water Resources Research}, publisher={American Geophysical Union (AGU)}, author={Fu, Congsheng and James, April L. and Wachowiak, Mark P.}, year={2012}, month={May} }
 @article{yao_mcconnell_james_fu_2012, title={Comparing and Modifying Eight Empirical Models of Snowmelt Using Data from Harp Experimental Station in Central Ontario}, volume={2}, ISSN={2231-4784}, url={http://dx.doi.org/10.9734/bjecc/2012/2249}, DOI={10.9734/bjecc/2012/2249}, number={3}, journal={British Journal of Environment and Climate Change}, publisher={Sciencedomain International}, author={Yao, Huaxia and McConnell, Christopher and James, April and Fu, Congsheng}, year={2012}, month={Jul}, pages={259–277} }
 @article{segura_james_lazzati_roulet_2012, title={Scaling relationships for event water contributions and transit times in small-forested catchments in Eastern Quebec}, volume={48}, DOI={10.1029/2012WR011890}, abstractNote={Recent studies of catchment hydrologic response are incorporating increasingly complex datasets to investigate model representation of spatial and temporal variability. In this paper, catchment rainfall‐runoff and stable isotope tracer response were modeled using a lumped conceptual model that integrates the unit hydrograph and isotope hydrograph separation methodologies. The model was applied across eight nested catchments (7 to 147 ha) for four rainstorms collected between summer and fall in 2001–2002, generating a usable 23 rainstorm datasets ranging from 1.2 to 10.3 h in length and spanning variability in environmental conditions related to storm characteristics (size and intensity) and antecedent moisture. Monte Carlo simulations were run for four model structures of varying complexity and evaluated using a Generalized Likelihood Uncertainty Estimation (GLUE) approach. We found that a model of intermediate complexity was adequate to model all catchment‐storm pairs. Relationships between the parameters of the best model and catchment and storm characteristics were sought. We found that the fraction of effective rainfall routed as event water was correlated to rainstorm size but insensitive to catchment size, indicating that it is controlled by environmental conditions such as storm intensity and size. The mean transit time of event water decreased with increasing rainstorm size, indicating increased connectivity during larger rainstorms. Finally, a linear relation was found between the mean transit time of event water and catchment size suggesting that the time it takes for event water to be transferred to the stream is directly related to catchment size, particularly for catchments greater than 30 ha.}, number={7W07502}, journal={Water Resources Research}, author={Segura, C. and James, A.L. and Lazzati, D. and Roulet, N.T.}, year={2012} }
 @article{johnson_shear_james_2011, title={Identifying ecohydrological patterns in natural forested wetlands useful to restoration design}, volume={5}, ISSN={1936-0584}, url={http://dx.doi.org/10.1002/eco.227}, DOI={10.1002/eco.227}, abstractNote={ABSTRACT}, number={3}, journal={Ecohydrology}, publisher={Wiley}, author={Johnson, Yari Ben and Shear, Theodore Henry and James, April Lynda}, year={2011}, month={May}, pages={368–379} }
 @article{james_mcdonnell_tromp-van meerveld_peters_2010, title={Gypsies in the palace: experimentalist's view on the use of 3-D physics-based simulation of hillslope hydrological response}, volume={24}, ISSN={0885-6087}, url={http://dx.doi.org/10.1002/hyp.7819}, DOI={10.1002/hyp.7819}, abstractNote={Abstract}, number={26}, journal={Hydrological Processes}, publisher={Wiley}, author={James, April L. and McDonnell, Jeffrey J. and Tromp-van Meerveld, Ilja and Peters, Norman E.}, year={2010}, month={Dec}, pages={3878–3893} }
 @article{mcdonnell_mcguire_aggarwal_beven_biondi_destouni_dunn_james_kirchner_kraft_et al._2010, title={How old is streamwater? Open questions in catchment transit time conceptualization, modelling and analysis}, volume={24}, ISSN={0885-6087 1099-1085}, url={http://dx.doi.org/10.1002/hyp.7796}, DOI={10.1002/hyp.7796}, abstractNote={The time water spends travelling subsurface through a catchment to the stream network (i.e. the catchment water transit time) fundamentally describes the storage, flow pathway heterogeneity and sou ...}, number={12}, journal={Hydrological Processes}, publisher={Wiley}, author={McDonnell, J. J. and McGuire, K. and Aggarwal, P. and Beven, K. J. and Biondi, D. and Destouni, G. and Dunn, S. and James, A. and Kirchner, J. and Kraft, P. and et al.}, year={2010}, month={May}, pages={1745–1754} }
 @article{james_roulet_2009, title={Antecedent moisture conditions and catchment morphology as controls on spatial patterns of runoff generation in small forest catchments}, volume={377}, ISSN={0022-1694}, url={http://dx.doi.org/10.1016/j.jhydrol.2009.08.039}, DOI={10.1016/j.jhydrol.2009.08.039}, abstractNote={Although existing empirical studies of runoff generation in headwater catchments have provided evidence of runoff mechanisms, contributing sources and active flowpaths from forest catchments around the world, our understanding of how hydrologic and biological processes vary and aggregate in space within headwater systems remains poor. In this study, we examine the spatial patterns of storm runoff generation from eight small nested forest catchments ranging in size from 7 to 147 ha, as a function of antecedent moisture conditions and catchment morphology. The catchments, located in the formerly glaciated terrain of Mont Saint-Hilaire, Quebec, Canada, are complex in both their topographic and subsurface characterization. Hydrologic response from the eight catchments shows a strong nonlinear change with antecedent moisture conditions consistent with the hypothesis of different ‘states-of-wetness’. With the transition from wet to dry conditions, local groundwater stores become depleted in some ephemeral catchments, variable source areas shrink and new-water delivered by shallow-subsurface stormflow and the transient development of perched water in valley-bottoms can account for much larger percentages of total runoff (up to 76% of total runoff). For the five storm events, no consistent pattern in percent new-water delivery was observed. However, for the storms observed under dry conditions, larger magnitudes of new water were generated from the three largest catchments attributable to basin morphology, while storms observed under wet conditions exhibited no consistent pattern, with larger variability among the smaller catchments. The results presented here illustrate the complexity of influences of antecedent moisture conditions and catchment morphology on spatial patterns of runoff generation in headwater systems.}, number={3-4}, journal={Journal of Hydrology}, publisher={Elsevier BV}, author={James, A.L. and Roulet, N.T.}, year={2009}, month={Oct}, pages={351–366} }
 @article{tromp-van meerveld_james_mcdonnell_peters_2008, title={A reference data set of hillslope rainfall-runoff response, Panola Mountain Research Watershed, United States}, volume={44}, ISSN={0043-1397}, url={http://dx.doi.org/10.1029/2007wr006299}, DOI={10.1029/2007wr006299}, abstractNote={Although many hillslope hydrologic investigations have been conducted in different climate, topographic, and geologic settings, subsurface stormflow remains a poorly characterized runoff process. Few, if any, of the existing data sets from these hillslope investigations are available for use by the scientific community for model development and validation or conceptualization of subsurface stormflow. We present a high‐resolution spatial and temporal rainfall‐runoff data set generated from the Panola Mountain Research Watershed trenched experimental hillslope. The data set includes surface and subsurface (bedrock surface) topographic information and time series of lateral subsurface flow at the trench, rainfall, and subsurface moisture content (distributed soil moisture content and groundwater levels) from January to June 2002.}, number={6}, journal={Water Resources Research}, publisher={American Geophysical Union (AGU)}, author={Tromp-van Meerveld, H. J. and James, A. L. and McDonnell, J. J. and Peters, N. E.}, year={2008}, month={Jun} }
 @article{james_roulet_2007, title={Investigating hydrologic connectivity and its association with threshold change in runoff response in a temperate forested watershed}, volume={21}, ISSN={0885-6087 1099-1085}, url={http://dx.doi.org/10.1002/hyp.6554}, DOI={10.1002/hyp.6554}, abstractNote={Abstract}, number={25}, journal={Hydrological Processes}, publisher={Wiley}, author={James, April L. and Roulet, Nigel T.}, year={2007}, pages={3391–3408} }
 @article{james_roulet_2006, title={Investigating the applicability of end-member mixing analysis (EMMA) across scale: A study of eight small, nested catchments in a temperate forested watershed}, volume={42}, ISSN={0043-1397}, url={http://dx.doi.org/10.1029/2005WR004419}, DOI={10.1029/2005WR004419}, abstractNote={Current interest in multicatchment hydrologic studies challenges the use of geochemical mixing models across scale, where changes in stream water chemistry from catchment to catchment may indicate (1) changes in the proportional contributions of end‐members, (2) changes in the geochemical signatures of end‐members in space, or (3) changes in the geochemical signatures of end‐members in time. In this study we examine stream water chemistry from a series of eight nested catchments in a 1.47 km2 temperate forest watershed in southern Quebec for evidence of contributing end‐members. We use eigenvector and residual analysis (Hooper, 2003) of the multivariate stream water chemistry records to estimate the dimensionality of the mixing space for each individual catchment, indicating the number of contributing end‐members. Using the mixing space of the largest, highest‐order catchment (1.47 km2), we evaluate its ability to predict stream water chemistry in the seven upstream catchments, representing progressively smaller areas. We observe significant spatial variation in ionic mixing ratios within the 147 ha watershed. Only spatial testing across catchments allowed us to identify appropriate conservative tracers most compatible with the application of a single mixing model across scale. On the seasonal timescale, groundwater geochemistry changes significantly due to the recharge from spring snowmelt, indicating a mixture of two groundwater end‐members of varying age. On the timescale of storm events, shallow perched water and throughfall provide geochemical signatures consistent with physical mixing while unsaturated zone soil water sampled from local pockets of glacial till does not. Our results suggest cautious application of end‐member mixing analysis (EMMA) for multicatchment studies.}, number={8}, journal={Water Resources Research}, publisher={American Geophysical Union (AGU)}, author={James, April L. and Roulet, Nigel T.}, year={2006}, month={Aug} }
 @article{wang_trautz_cook_finsterle_james_birkholzer_1999, title={Field tests and model analyses of seepage into drift}, volume={38}, ISSN={0169-7722}, url={http://dx.doi.org/10.1016/s0169-7722(99)00019-4}, DOI={10.1016/s0169-7722(99)00019-4}, abstractNote={This paper focuses on field test results and model analyses of the first set of five niche seepage tests conducted in the Exploratory Studies Facility at Yucca Mountain. The test results suggest that (1) a niche opening (short drift excavated for this study) acts as a capillary barrier; (2) a seepage threshold exists; and (3) the seepage is a fraction of the liquid released above the ceiling. Before seepage quantification, air injection and liquid release tests at two niche locations were conducted to characterize the fracture flow paths. Nearly two-order-of-magnitude changes in air permeability values were measured before and after niche excavation. The dyed liquid flow paths, together with a localized wet feature potentially associated with an ambient flow path, were mapped during dry excavation operations. After niche excavation, the seepage is quantified by the ratio of the water mass dripped into a niche to the mass released above the opening at selected borehole intervals. For the first set of five tests conducted at Niche 3650 site, the ratios range from 0% (no dripping for two tests) to 27.2%. Changes in flow path distributions and water accumulation near seepage threshold were observed on the niche ceiling. The seepage test results compare reasonably well with model results without parameter adjustments, using capillary barrier boundary condition in the niche and two-dimensional and three-dimensional conceptualizations to represent discrete fracture and fracture network for the flow paths. Model analyses of the niche tests indicate that the seepage is very sensitive to the niche boundary condition and is moderately sensitive to the heterogeneity of the fracture flow paths and to the strengths of matrix imbibition. Strong capillary strength and large storage capacity of the fracture flow paths limit the seepage. High permeability value also enhances diversion and reduces seepage for low liquid release rate.}, number={1-3}, journal={Journal of Contaminant Hydrology}, publisher={Elsevier BV}, author={Wang, J.S.Y and Trautz, R.C and Cook, P.J and Finsterle, S and James, A.L and Birkholzer, J}, year={1999}, month={May}, pages={323–347} }
 @article{bennett_james_mckone_oldenburg_1998, title={On uncertainty in remediation analysis: variance propagation from subsurface transport to exposure modeling}, volume={62}, ISSN={0951-8320}, url={http://dx.doi.org/10.1016/s0951-8320(97)00160-9}, DOI={10.1016/s0951-8320(97)00160-9}, abstractNote={Addressing long-term potential human exposures to, and health risks from contaminants in the subsurface environment requires the use of models. Because these models must project contaminant behavior into the future, and make use of highly variable landscape properties, there is uncertainty associated with predictions of long-term exposure. Many parameters used in both subsurface contaminant transport simulation and health risk assessment have variance owing to uncertainty and/or variability. These parameters are best represented by ranges or probability distributions rather than single values. Based on a case study with information from an actual site contaminated with trichloroethylene (TCE), we demonstrate the propagation of variance in the simulation of risk using a complex subsurface contaminant transport simulation model integrated with a multi-pathway human health risk model. Ranges of subsurface contaminant concentrations are calculated with the subsurface transport simulator T2VOC (using the associated code ITOUGH2 for uncertainty analysis) for a three-dimensional system in which TCE migrates in both the vadose and saturated zones over extended distances and time scales. The subsurface TCE concentration distributions are passed to CalTOX, a multimedia, multi-pathway exposure model, which is used to calculate risk through multiple exposure pathways based on inhalation, ingestion and dermal contact. Monte Carlo and linear methods are used for the propagation of uncertainty owing to parameter variance. We demonstrate how rank correlation can be used to evaluate contributions to overall uncertainty from each model system. In this sample TCE case study, we find that although exposure model uncertainties are significant, subsurface transport uncertainties are dominant.}, number={1-2}, journal={Reliability Engineering & System Safety}, publisher={Elsevier BV}, author={Bennett, D.H. and James, A.L. and McKone, T.E. and Oldenburg, C.M.}, year={1998}, month={Oct}, pages={117–129} }
 @article{james_oldenburg_1997, title={Linear and Monte Carlo uncertainty analysis for subsurface contaminant transport simulation}, volume={33}, ISSN={0043-1397}, url={http://dx.doi.org/10.1029/97wr01925}, DOI={10.1029/97wr01925}, abstractNote={Transport simulation can be used to predict subsurface contaminant distributions and the effectiveness of site remediation technologies. Because of the uncertainty inherent in subsurface transport prediction, an integral part of predictive modeling is uncertainty analysis. We have investigated the uncertainty of simulated trichloroethylene (TCE) concentrations due to parameter uncertainty and variation in conceptual model. The transport simulation is performed with T2VOC, a three‐dimensional integral finite difference code for three‐phase (gas, aqueous, non‐aqueous phase liquid), three‐component (air, water, volatile organic compound), nonisothermal subsurface flow. Our modeling is based on an actual site and considers a three‐dimensional system with a thick vadose zone (25 m) into which 35,000 kg of TCE was disposed of in surface trenches over 10 years. Subsurface transport involves TCE moving in the vadose and saturated zones from the source trench toward a nearby residence and includes the processes of advection, diffusion, and adsorption over extended distances and timescales. Uncertainties in the calculated concentrations due to variance in the major transport parameters are quantified using the inverse modeling code ITOUGH2. ITOUGH2 calculates uncertainty in the T2VOC simulation by both first‐order, second‐moment (FOSM) and Monte Carlo analyses. Significant uncertainty in simulated TCE concentrations at a site of potential human exposure is observed owing to uncertainty in permeability, porosity, diffusivity, chemical solubility, and adsorption within a single conceptual model. For the case study considered the linear FOSM analysis generally captures the uncertainty range calculated by the more accurate Monte Carlo method. Calculations also show that significant output uncertainty is introduced by conceptual model variation. Because human exposure and health risk depend strongly on contaminant concentrations, risk assessment and remediation selection based on transport simulation is meaningful only if the analysis includes quantitative estimates of transport simulation uncertainty.}, number={11}, journal={Water Resources Research}, publisher={American Geophysical Union (AGU)}, author={James, April L. and Oldenburg, Curtis M.}, year={1997}, month={Nov}, pages={2495–2508} }