PUBLICATIONS

Highlighted Publications

Is streamflow in the Upper Colorado River Basin predictable? A look at 1,000 years of change

Streamflow in the Upper Colorado River Basin doesn’t just change year to year, it follows long-term cycles of variability and predictability. We looked at over a thousand years of streamflow data to understand when and why annual river flow becomes more or less predictable. Periods of high predictability tend to have lower streamflow variability, while low predictability periods show greater fluctuations and inconsistencies. We show that streamflow predictability fluctuates over time and large changes often align with major droughts.

View article

A new reservoir module for the ParFlow physical hydrology model

Reservoirs are commonplace around the world, with over 80,000 in the US alone. Despite this, reservoir operations are often missing from physical hydrology models. We added a reservoir module to the hydrologic model ParFlow. The new module allows users to directly simulate reservoir storage and releases within hydrologic simulations. This implementation will increase the accuracy of existing simulations in managed systems, and allow users answer new questions about how reservoirs and the environment interact.

View article

Groundwater recovery in Arizona may be driven more by recharge from surface water than groundwater regulation

Arizona relies heavily on groundwater, but long-term water sustainability is a growing concern. Our study examines how groundwater levels have changed across the state considering groundwater regulation and access to surface water. Across the state deeper wells are becoming more common, especially in regulated and groundwater-dependent areas. Groundwater levels and storage are declining statewide, but declines are less severe where groundwater regulations exist and imported Colorado River water is used for recharge. A closer look suggests that groundwater recovery is highly localized and mainly driven by surface water imports rather than reduced pumping.

View article

< archived highlights

Complete Publication List Peer Reviewed Publications

West, BD, RM Maxwell, LE Condon (2025). A scalable and modular reservoir implementation for large-scale integrated hydrologic simulations. Hydrology and Earth System Sciences, Volume 29, No. 1.
Yang, C, LE Condon, RM Maxwell (2025). Unravelling groundwater–stream connections over the continental United States. Nature Water, 06 January 2025. Press Release Summary Video
Patricia, P, B Rajagopalan, LE Condon (2025). Understanding the temporal variability and predictability of streamflow signatures in the Colorado River Basin. Journal of Hydrology, Volume 648, 2025, 132386, ISSN 0022-1694. (Access GitHub Repository)
Tadych, DE, M Ford, B Colby, LE Condon (2024). Historical patterns of well drilling and groundwater depth in Arizona considering groundwater regulation and surface water access. Journal of the American Water Resources Association (JAWR), 04 October 2024, JAWR-23-0073-P.
Hull, R, E Leonarduzzi, L De La Fuente, HV Tran, A Bennett, P Melchior, RM Maxwell and LE Condon (2024). Simulation-based inference for parameter estimation of complex watershed simulators. Hydrology and Earth Systems Sciences, 28(20). (Access Codes)
Triplett, AK, G Artavanis, WM Hasling, RM Maxwell, A Defnet, AM Johnson, W Lytle, A Bennett, E Leonarduzzi, LK Gallagher and LE Condon (2024). SubsetTools: A Python package to subset data to build and run ParFlow hydrologic models. Journal of Open Source Software, 9(99), 6752. (Access Subsettools)
Defnet , A, W Hasling, LE Condon, A Johnson, G Artavanis, A Triplett, W Lytle and R Maxwell (2024). hf_hydrodata: A Python package for accessing hydrologic simulations and observations across the United States. Journal of Open Source Software, 9(99), 6623. (Access Software Repository)
Mekha P, Z Reed-Spitzer, LE Condon, B Colby (2024). Investigating Economic and Climate Signals in Groundwater Data. Water Economics and Policy, Vol. 10, No. 3, 2024 2450006.
Bennett, A, H Tran, L De la Fuente, A Triplett, Y Ma, P Melchior, RM Maxwell, LE Condon (2024). Spatio-Temporal Machine Learning for Regional to Continental Scale Terrestrial Hydrology. Journal of Advances in Modeling Earth Systems, Volume 16, Issue 6, 12 June 2024. (Acccss Data Sets and Code)
Steyaert, JC, LE Condon (2024). Synthesis of historical reservoir operations from 1980 to 2020 for the evaluation of reservoir representation in large-scale hydrologic models. Hydrology and Earth System Sciences, Volume 28, issue 4 HESS, 28, 1071–1088, 2024. (Access Data Sets)
Brookfield, AE, H Ajami, RWH Carroll, C Tague, PL Sullivan, LE Condon (2023). Recent advances in integrated hydrologic models: Integration of new domains. Journal of Hydrology, Volume 620, Part B, 2023, 129515.
De la Fuente, LA, MR Ehasnai, HJ Gupta, LE Condon (2024). Toward interpretable LSTM-based modeling of hydrological systems. Hydrology and Earth System Sciences, Vol 28 Issue 4, 945–971. (Acccss Data Sets and Code) (See the research Highlights)
Ma, Y, E Leonarduzzi, A Defnet, P Melchior, LE Condon, and RM Maxwell (2023). Water Table Depth Estimates over the Contiguous United States Using a Random Forest Model. Groundwater, 05 October 2023.
Yang, C, DT Tijerina-Kreuzer, HV Tran, LE Condon, and RM Maxwell (2023). A High-Resolution, 3D Groundwater-Surface Water Simulation of the Contiguous US: Advances in the Integrated ParFlow CONUS 2.0 Modeling Platform. Journal of Hydrology, 626: 130294.
Tran, H, C Yang, LE Condon, and RM Maxwell (2023). The Budyko Shape Parameter as a Descriptive Index for Streamflow Loss. Frontiers in Water, 5, 29 September.
Tijerina-Kreuzer, D, JS Swilley, HV Tran, J Zhang, B West, C Yang, LE Condon, and RM Maxwell (2023). Continental Scale Hydrostratigraphy: Basin-Scale Testing of Alternative Data-Driven Approaches. Groundwater, 28 September 2023.
Swilley, JS, D Tijerina-Kreuzer, HV Tran, J Zhang, C Yang, LE Condon and RM Maxwell (2023). Continental Scale Hydrostratigraphy: Comparing Geologically Informed Data Products to Analytical Solutions. Groundwater, 15 September 2023.
Triplett, A, LE Condon (2023). Climate-Warming-Driven Changes in the Cryosphere and Their Impact on Groundwater–Surface-Water Interactions in the Heihe River Basin. Hydrology and Earth Systems Sciences, 27 (14) 22763-2785. (Access the Codes)
Spinti, RA, LE Condon, J Zhang (2023). The Evolution of Dam Induced River Fragmentation in the United States. Nature Communications, 14, 3820. (Access the Datasets Access the Codes)
Farley, A, LE Condon (2023). Exploring the Signal Filtering Properties of Idealized Watersheds Using Spectral Analysis. Advances in Water Resources, 178(104441).
Condon, LE, A Farley, S Jourdain, P O’leary, P Avery, L Gallagher, C Chennault, RM Maxwell (2023). ParFlow Sand Tank: A tool for groundwater exploration. Journal of Open Source Education, 6(61), 179. (Access the Codes)
De la Fuente, L, HV Gupta, LE Condon (2023). Toward a Multi-Representational Approach to Prediction and Understanding, in Support of Discovery in Hydrology. Water Resources Research, 59 (1). (Access the Codes)
Leonarduzzi E, H Tran, V Bansal V, RB Hull, L De la Fuente, LA Bearup, P Melchior, LE Condon and RM Maxwell (2022) Training machine learning with physics-based simulations to predict 2D soil moisture fields in a changing climate. Frontiers in Water, 4:927113.
Gallagher, LK, AJ Farley, C Chennault, S Cerasoli, S Jourdain, P O’Leary, LE Condon & RM Maxwell (2022). The ParFlow Sandtank: An Interactive education tool making invisible groundwater visible. Frontiers in Water, 4.
Baru C, M Pozmantier , I Altintas, LE Condon et al (2022). Enabling AI innovation via data and model sharing: An overview of the NSF Convergence Accelerator Track D. AI Magazine, 43(1):93-104.
Steyaert, JC, LE Condon, S Turner, N Voisin (2022). ResOpsUS, A dataset of historical reservoir operations in the contiguous United States. Scientific Data, 9(34). (Access the Datasets. (See the research Highlights)
Tran, H, J Zhang, MM O’Neill, A Ryken, LE Condon and RM Maxwell (2022). A hydrological simulation dataset of the Upper Colorado River Basin from 1983 to 2019. Scientific Data, 9(16).
Tran, H, E Leonarduzzi, L De la Fuente, RB Hull, V Bansal, C Chennault, P Gentine, P Melchior, LE Condon, and RM Maxwell (2021). Development of a Deep Learning Emulator for a Distributed Groundwater–Surface Water Model: ParFlow-ML. Water, 13, no. 23. (Access the Codes)
Maxwell, RM, LE Condon, and P Melchior (2021). A Physics-Informed, Machine Learning Emulator of a 2D Surface Water Model: What Temporal Networks and Simulation-Based Inference Can Help Us Learn about Hydrologic Processes. Water, 13, no. 24. (Access the Codes)
Condon, LE, S Kollet, MFP Bierkens, GE Fogg, RM Maxwell, MC Hill, HH Fransen, et al (2021). Global Groundwater Modeling and Monitoring: Opportunities and Challenges. Water Resources Research, 57, no. 12: e2020WR029500.
Gallagher, LK, JM Williams, D Lazzeri, C Chennault, S Jourdain, P O’Leary, LE Condon, and RM Maxwell (2021). Sandtank-ML: An Educational Tool at the Interface of Hydrology and Machine Learning. Water, 13, no. 23.
O’Neill, MMF, DT Tijerina, LE Condon, and RM Maxwell (2021). Assessment of the ParFlow–CLM CONUS 1.0 Integrated Hydrologic Model: Evaluation of Hyper-Resolution Water Balance Components across the Contiguous United States. Geoscientific Model Development, 14, no. 12: 7223–54.
Turner, SWD, JC Steyaert, LE Condon, and N Voisin (2021). Water Storage and Release Policies for All Large Reservoirs of Conterminous United States. Journal of Hydrology, 603: 126843. (Access the Datasets Access the Codes)
Gleeson T, T Wagener, P Döll, SC Zipper, C West, Y Wada, R Taylor, B Scanlon, R Rosolem, S Rahman, N Oshinlaja, R Maxwell, MH Lo, H Kim, M Hill, A Hartmann, G Fogg, JS Famiglietti, A Ducharne, I de Graaf, M Cuthbert, LE Condon, E Bresciani, MFP Bierkens,(2021) GMD Perspective: The Quest to Improve the Evaluation of Groundwater Representation in Continental to Global Scale Models. Geoscientific Model Development: Discussion, 1–59.
Zhang, J, LE Condon, H Tran and RM Maxwell (2021). A National topographic dataset for hydrological modeling over the contiguous United States, Earth System Science Data. Earth System Science Data, 13, 3263–3279. (Access the Codes)
Tijerina, D, LE Condon, K FitzGerald, A Dugger, MM O’Neil, K Sampson, D Gochis and RM Maxwell (2021), Continental Hydrologic Intercomparison Project, Phase 1: A Large-Scale Hydrologic Model Comparison Over the Continental United States. Water Resources Research, 57, e2020WR028931
Markovich, KH, LE Condon, KC Carroll R Purtschert, and JC McIntosh (2021). A mountain-front recharge component characterization approach combining groundwater age distributions, noble gas thermometry, and fluid and energy transport modeling. Water Resources Research, 57. (Access the Codes)
Rapp, G, LE Condon, KH Markovich (2020). Sensitivity of Simulated Mountain-Block Hydrology to Subsurface Conceptualization, Water Resources Research, 56, e2020WR027714. (Access the Codes)
DeGraaf, I, LE Condon and RM Maxwell (2020). Hyper-resolution continental-scale 3D-aquifer parameterization for groundwater modelling. Water Resources Research, 56, e2019WR026004. (Access the Datasets)
Tran, H, J Zhang, JM Cohard, LE Condon and RM Maxwell (2020). Simulating groundwater-streamflow connections in the Upper Colorado River Basin. Groundwater, 58:392-405.
Fayaz, N, LE Condon and DG Chandler (2020). Evaluating the sensitivity of projected reservoir reliability to the choice of climate projection: A case study of Bull Run Watershed, Portland, Oregon. Water resources Management, 34:1991–2009.
Kuffour, BNO, NB Engdahl, CS Woodward, LE Condon, S Kollet, and RM Maxwell (2020). Simulating coupled surface–subsurface flows with ParFlow v3.5.0: capabilities, applications, and ongoing development of an open-source, massively parallel, integrated hydrologic model. Geoscientific Model Development, 13(3), 1373-1397. (Access the Codes)
Condon, LE, KH Markovich, CA Kelleher, JJ McDonnell, G Ferguson and JC McIntosh (2020). Where is the bottom of a watershed? Water Resources Research, 56, e2019WR026010. (See the research Highlights)
Van Dusen, P, B Rajagopalan, DJ Lawrence, LE Condon, G Smilie, S Gangopadhyay and T Pruitt (2020). 21st Century Flood Risk Projections and Selected Sites for the U.S. National Parks Service. Climate Risk Management, 28,100211.
Condon, LE, AL Atchley and RM Maxwell (2020). Evapotranspiration depletes groundwater under warming over the contiguous United States. Nature Communications, 11(873). (See the research Highlights)
Markovich, KH, AH Manning, LE Condon, JC McIntosh (2019). Mountain-block Recharge: A Review of Current Understanding. Water Resources Research, 55.
Condon, LE and RM Maxwell (2019). Simulating the sensitivity of evapotranspiration and streamflow to large-scale groundwater depletion. Science Advances, 5(6): eaav4574. (Access the Codes.)
Hein, A, LE Condon and RM Maxwell (2019). Evaluating the relative importance of precipitation, temperature and land-cover change in the hydrologic response to extreme meteorological drought conditions over the North American High Plains. Hydrology and Earth System Sciences, 23.
Condon, LE and RM Maxwell (2019). Modified priority flood and global slope enforcement algorithm for topographic processing in physically based hydrologic modeling applications. Computers & Geosciences. 126:73-83. (Access the Codes)
Ehmann, C Kelleher, LE Condon (2018). Monitoring turbidity from above: Deploying small unoccupied aerial vehicles to image in-stream turbidity. Hydrological Processes, 33(6):1013-1021.
Maxwell, RM, LE Condon, M Danesh-Yazdi, and LA Bearup (2018).Exploring source water mixing and transient residence time distributions of outflow and evapotranspiration with an integrated hydrologic model and Lagrangian particle tracking approach. Ecohydrology, 12(1).
Kelleher, C, CA Scholz, LE Condon, and M Reardon (2018), Drones in geoscience research: The sky is the only limit. Eos. 99.
Danesh-Yazdi, M., J Klaus, LE Condon and RM Maxwell (2018). Bridging the gap between numerical solutions of travel time distributions and analytical storage selection functions. Hydrological Processes, 32(8):1063-1076, doi:10.1002/hyp.11481
Condon, LE and RM Maxwell (2017). Systematic shifts in Budyko relationships caused by groundwater storage changes. Hydrology and Earth System Sciences, 21(2): p. 1117-1135, doi:10.5194/hess-21-1117-2017
Maxwell, RM and LE Condon (2016). Connections between groundwater flow and transpiration partitioning. Science, 353(6297):377-380 doi:10.1126/science.aaf7891.
Maxwell, RM, LE Condon, SJ Kollet, K Maher, R Haggerty, and MM Forrester (2016). The imprint of climate and geology on the residence times of groundwater. Geophysical Research Letters, 43:2, 701-708, doi:10.1002/2015GL066916.
Condon, LE and RM Maxwell (2015). Evaluating the relationship between topography and groundwater using outputs from a continental-scale integrated hydrology model. Water Resources Research, 51,(8):6602-6621 doi:10.1002/2014WR016774.
Condon, LE, AS Hering, and RM Maxwell (2015). Quantitative assessment of groundwater controls across major US river basins using a multi-model regression algorithm. Advances in Water Resources, 82:106-123. doi:10.1016/j.advwatres.2015.04.008.
Maxwell, RM, LE Condon, and SJ Kollet (2015). A high resolution simulation of groundwater and surface water over most of the continental US with the integrated hydrologic model ParFlow v3. Geoscientific Model Development, 8:923-937. doi:10.5194/gmd-8-1-2015.
Bierkens, MFP, V Bell, P Burek, N Chaney, LE Condon, C David, A de Roo, P Doell, N Drost, J Famiglietti, M Florke, D Gochis, P Houser, R Hut, J Keune, S Kollet, RM Maxwell, J Reager, L Samaniego, E Sutandudjaja, N van de Giesen, H Winsemius, E Wood (2015). Hyper-resolution global hydrological modelling: what’s next? Hydrologic Processes, 29(2), 310-320. doi:10.1002/hyp.10391.
Condon, LE, S Gangopadhyay, and T Pruitt (2015). Climate change and non-stationary flood risk for the Upper Truckee River Basin. Hydrology and Earth System Sciences, 19(1):159-175. doi: 10.5194/hess-19-159-2015
Condon, LE and RM Maxwell (2014). Feedbacks between managed irrigation and water availability: Diagnosing temporal and spatial patterns using an integrated hydrologic model. Water Resources Research, 50(3):2600-2616. doi:10.1002/2013WR014868.
Condon, LE and RM Maxwell (2014). Groundwater-fed irrigation impacts spatially distributed temporal scaling behavior of the natural system: A spatio-temporal framework for understanding water management impacts. Environmental Research Letters, 9(3), 034009. doi:10.1088/1748-9326/9/3/034009.
Condon, LE and RM Maxwell (2013). Implementation of a linear optimization water allocation algorithm into a fully integrated physical hydrology model. Advances in Water Resources, 60:135-147. doi:10.1016/j.advwatres.2013.07.012.
Condon, LE, RM Maxwell, and S Gangopadhyay (2013). The impact of subsurface conceptualization on land energy fluxes. Advances in Water Resources, 60:188-203. doi:10.1016/j.advwatres.2013.08.001.
Gong, G, L Wang, LE Condon, A Shearman, and U Lall (2010). A Simple Framework for Incorporating Seasonal Streamflow Forecasts into Existing Water Resources Management Practices. The JAWRA Journal of the American Water Resources Association (JAWRA), 46(3):574-585. doi:10.1111/j.1752-1688.2010.00435.x.

Technical Reports

Payton, EA, AO Pinson, T Asefa, LE Condon, L-AL Dupigny-Giroux, BL Harding, J Kiang, DH Lee, SA McAfee, JM Pflug, I Rangwala, HJ Tanana, DB Wright (2023). Ch. 4. Water. Fifth National Climate Assessment. Crimmins, AR, CW Avery, DR Easterling, KE Kunkel, BC Stewart, TK Maycock, Eds. U.S. Global Change Research Program, Washington, DC, USA.
Condon, LE, J Ruiz, P Antin, LA Ikner, J Buizer, SB Megdal, S Collinge, KJ Ptten, NL Esquerra (2023). The Future of Agriculture & Food Production in a Drying Climate. Presidential Advisory Commission Report, August 2023.
Maxwell, RM, SJ Kollet, SG Smith, CS Woodward, RD Falgout, IM Ferguson, N Engdahl, LE Condon, S Lopez, J Gilbert, L Bearup, J Jefferson, C Prubilick, C Baldwin, WJ Bosl, R Hornung, and S Ashby (2014). ParFlow User’s Manual, International Ground Water Modeling Center, GMWI 2014-01 v.693.
Condon, LE, K Blickenstaff, and S Gangopadhyay (2013). Mojave River Watershed Climate Change Assessment. US Department of the interior, Bureau of Reclamation, Technical Memorandum No. 86-68210-2013-04.
Blickenstaff, K, SG Gangopadhyay, I Ferguson, LE Condon, and T Pruitt (2013). Climate Change Analysis for the Santa Ana River Watershed. US Department of the Interior, Bureau of Reclamation, Technical Memorandum No. 86-68210-2013-02.