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2025

 

64. Hirmas, D.R., H. Ajami, M.G. Sena, X. Zhang, X. Cao, B. Li, K.M. Jarecke, S.A. Billings, J.C. Pachon, L. Li, J. B. Nippert, L.F. Souza, A.N. Flores, P.L. Sullivan. 2025. Predicting Soil Interpedal Macroporosity and Hydraulic Conductivity Dynamics: A Model for Integrating Laser-scanned Profile Imagery with Soil Moisture Sensor Data. Water Resources Research, Accepted

 

63. Rahman, ATM S.*, J. Šimůnek, S.A. Bradford, H. Ajami, M.B. Meles, L. Chen*, A. Szymkiewicz, M. Pawlowicz, J.S. Acero Triana*, J. A. Casillas Trasvina, S. Beegum. 2025. A New Externally Coupled, Physically-based Multi-model Framework for Simulating Subsurface and Overland Flow Hydrological Processes on Hillslopes. Journal of Hydrology, https://doi.org/10.1016/j.jhydrol.2025.133842

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62. Stewart, R. D., M. Flury, H. Ajami, R.G. Anderson, T.R. Green, Y. Jin, A. Patrignani, R. Shillito, W. Zhang, M.R.A. Najm, E. Babaeian, M. Berli, E.N.J. Brookshire, A.L.M. Daigh, S. Franklin, J. Giovando, R. Heinse, J. Heitman, J. Huang,  T. Kelleners,  M. Naseri,  T.E. Ochsner,  J. Radolinski,  M. Sadeghi,  S. Sasidharan,  M.K. Shukla,  M. Tuller,  O. Wendroth,  J. Wu,  B. M. Wyatt,  Y. Yang,  Y. Yu,  Z.F.  Zhang. 2025. Emerging Issues and Research Opportunities in Vadose Zone Processes. Vadose Zone Journal, 24, e70030. https://doi.org/10.1002/vzj2.70030

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61.Tomar, S.*, D.R. Hirmas, R.C. Graham, M. Cole, H. Ajami, A. Frisbie, A.B. Gray, E. Blake. 2025. Soil Development Along An Elevational Transect in the Arid White Mountains, California. Soil Science Society of America Journal, 89, e70083. https://doi.org/10.1002/saj2.70083

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60. Singh, N.K., S.M. Saia, R. Bhattacharya, H. Ajami, D.M. Borrok. 2025. Unraveling the Causal Influences of Drought and Crop Production on Groundwater Levels Across the Contiguous United States. PNAS Nexus, https://doi.org/10.1093/pnasnexus/pgaf129

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​59. Nimmo, J. R., I. Wiekenkamp, R. Araki, J. Groh, N.K. Singh, O. Crompton, B.M. Wyatt, H. Ajami, D. Giménez, D.R. Hirmas, P.L. Sullivan, M. Sprenger. 2025. Identifying Preferential Flow From Soil Moisture Time Series: Review of Methodologies. Vadose Zone Journal, 24, e70017. https://doi.org/10.1002/vzj2.70017

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58. Acero Triana, J.S.*, H. Ajami. S. Razavi. The Dilemma of Objective Function Selection for Sensitivity and Uncertainty Analyses of Semi-Distributed Hydrologic Models Across Spatial and Temporal Scales. Journal of Hydrology, https://doi.org/10.1016/j.jhydrol.2024.132482

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2024

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57. Jarecke, K.M., X. Zhang, R.M. Keen, M. Dumont, B. Li, K. Sadayappan, V. Moreno, H. Ajami, S.A. Billings, A.N. Flores, D.R. Hirmas, M.F. Kirk, L. Li, J. B. Nippert, K. Singha, P.L. Sullivan. Woody Encroachment Modifies Subsurface Structure and Hydrological Function. Ecohydrology, https://doi.org/10.1002/eco.2731

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56. Dhungel, R., R.G. Anderson, A.N. French,  T.H. Skaggs, H. Ajami, D. Wang. 2024. Intercomparison of Citrus Evapotranspiration Among Eddy Covariance, OpenET Ensemble Models, and the Water and Energy Balance Model (BAITSSS). Agricultural Water Management, 304, 109066. https://doi.org/10.1016/j.agwat.2024.109066

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55. Armengol, S.*, H. Ajami, J.S. Acero Triana, J. O. Sickman, L. Ortega. 2024. Isogeochemical Characterization of Mountain System Recharge Processes in the Sierra Nevada, California. Water Resources Research, 60, e2023WR035719. https://doi.org/10.1029/2023WR035719

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54. Meles, M.B., S. Bradford, A. Casillas-Trasvina, L. Chen*, G. Osterman, T. Hatch, H. Ajami, O. Crompton, L. Levers, I. Kisekka. 2024. Uncovering the Gaps in Managed Aquifer Recharge for Sustainable Groundwater Management: A Focus on Hillslopes and Mountains. Journal of Hydrology. https://doi.org/10.1016/j.jhydrol.2024.131615

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53. Meles, M.B., L. Chen*, C. Unkrich, H. Ajami, S. Bradford, J. Šimůnek, D.C. Goodrich. 2024. Computationally Efficient Watershed-Scale Hydrological Modeling: Integrating HYDRUS-1D and KINEROS2 for Coupled Surface-Subsurface Analysis. Journal of Hydrology. https://doi.org/10.1016/j.jhydrol.2024.131621

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​52. Zipper, S., A. Brookfield, H. Ajami, J.R. Ayers, C. Beightel, M.N. Fienen, T. Gleeson,  J. Hammond,  M. Hill,  A.D. Kendall,  B. Kerr,  D. Lapides,  M. Porter,  S. Parimalarenganayaki,  M.M. Rohde,  C. Wardropper. 2024. Streamflow Depletion Caused by Groundwater Pumping: Fundamental Research Priorities for Management-relevant Science. Water Resources Research, 60, e2023WR035727. https://doi.org/10.1029/2023WR035727

 

51. Yuan, Y.*, L. Wang, Z. Wei, H. Ajami, H. Wang, T. Du. 2024. Using Median Point in Keeling Plot to Reduce the Uncertainty of the Isotopic Composition of Evapotranspiration. Journal of Hydrometeorology. https://doi.org/10.1175/JHM-D-23-0133.1

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50. Duro, A. M.*, D.R. Hirmas, H. Ajami, S.A. Billings, X. Zhang, L. Li, A. Flores, V. Moreno, X. Cao, J. Guilinger, E. Oleghe, D. Giménez, A. Gray, P.L. Sullivan. 2024. Topographic Correction of Visible Near-Infrared Reflectance Spectra for Horizon-Scale Soil Organic Carbon Mapping. Soil Science Society of America Journal, 00, 00–00. https://doi.org/10.1002/saj2.20612

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49. Chen, L.*, J. Šimůnek, S.A. Bradford, H. Ajami, M.B. Meles. 2023. Coupling Water, Solute, and Sediment Transport into a New Computationally Efficient Hydrologic Model. Journal of Hydrology. https://doi.org/10.1016/j.jhydrol.2023.130495

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2023

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48. Lee, S.*, H. Ajami.2023. Comprehensive Assessment of Baseflow Responses to Long-term Meteorological Droughts across the United States. Journal of Hydrology. https://doi.org/10.1016/j.jhydrol.2023.130256

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  • Rivers may not recover from drought for years (UCR press release) 

  • River recovery from drought can take years (AGU Eos)

  • River recoveries can take years due to prolonged drought, lack of rain, study shows (Nature World News)

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47. Koop, A.N., D.R. Hirmas, S.A. Billings, L. Li, A. Cueva, X. Zhang, H. Wen, A. Nemes, L.F.T. Souza, H. Ajami, A.N. Flores, A.K. Rudick, A. Guthrie, L.M. Klamm, M. Unruh, P.L. Sullivan.2023. Is Macroporosity Controlled by Complexed Clay and Soil Organic Carbon? Geoderma 437, 116565. https://doi.org/10.1016/j.geoderma.2023.116565

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46. Brookfield, A.E., S. Zipper, A.D. Kendall, H. Ajami, J.M. Deines. 2023. Estimating Groundwater Pumping for Irrigation - A Method Comparison. Groundwater. https://doi.org/10.1111/gwat.13336

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45. Souza, L.F.T., D.R. Hirmas, P.L. Sullivan, D.C. Reuman, M.F. Kirk, L. Li, H. Ajami, H. Wen, M.V.M. Sarto, T.D. Loecke, A.K. Rudick, C.W. Rice, S.A. Billings. 2023. Root Distributions, Precipitation, and Soil Structure Converge to Govern Soil Organic Carbon Depth Distributions. Geoderma. 437, 116569.https://doi.org/10.1016/j.geoderma.2023.116569

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44. Brookfield, A.E., H. Ajami, R.W.H. Carroll, C. Tague, P.L. Sullivan, L.E. Condon.2023. Recent advances in integrated hydrologic models: Integration of new domains. Journal of Hydrology. 620, 129515. https://doi.org/10.1016/j.jhydrol.2023.129515

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43. Aiken, M.L., C.E. Pace, M. Ramachandran, K.A. Schwabe, H. Ajami, B.G. Link, S.C. Ying. 2023. Disparities in Drinking Water Manganese Concentrations in Domestic Wells and Community Water Systems in the Central Valley, CA, USA. Environmental Science and Technology. 57, 1987–1996. https://doi.org/10.1021/acs.est.2c08548

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2022

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42. Chen, L.*, J. Šimůnek, S.A. Bradford, H. Ajami, M.B. Meles. 2022. A Computationally Efficient Hydrologic Modeling Framework to Simulate Surface-Subsurface Hydrological Processes at the Hillslope Scale. Journal of Hydrology. https://doi.org/10.1016/j.jhydrol.2022.128539

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41. Stephens, C. M., L.A. Marshall, F.M. Johnson, H. Ajami, L. Lin, L.E.  Band. 2022. Spatial Variation in Catchment Response to Climate Change Depends on Lateral Moisture Transport and Nutrient Dynamics. Water Resources Research, 58, e2021WR030577. https://doi.org/10.1029/2021WR030577

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40. Acero Triana, J. S.*, H. Ajami. 2022. Identifying Major Hydrologic Change Drivers in a Highly Managed Transboundary Endorheic Basin: Integrating Hydro-ecological Models and Time-Series Data Mining Techniques. Water Resources Research, 58, e2022WR032281. https://doi.org/10.1029/2022WR032281

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39. Wen, H., P.L. Sullivan, S.A. Billings, H. Ajami, A. Cueva, A. Flores, D.R. Hirmas, A.N. Koop, K. Murenbeeld, X. Zhang, L. Li.2022. From Soils to Streams: Connecting Terrestrial Carbon Transformation, Chemical Weathering, and Solute Export Across Hydrological Regimes. Water Resources Research, 58, e2022WR032314. https://doi.org/10.1029/2022WR032314

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38. Schreiner-McGraw, A. P.*, H. Ajami, R.G. Anderson, D. Wang. 2022. Integrating Partitioned Evapotranspiration Data into Hydrologic Models: Vegetation Parameterization and Uncertainty Quantification of Simulated Plant Water Use. Hydrological Processes, 36(6), e14580. https://doi.org/10.1002/hyp.14580

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37. Bradly, T., H. Ajami, W. Porter. 2022. Ecological Transitions at the Salton Sea: Past, Present and Future, California Agriculture, https://calag.ucanr.edu/archive/?article=ca.2022a0004

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36. Zipper, S.C., W.H. Farmer, A. Brookfield, H. Ajami, H.W. Reeves, C. Wardropper, J.C. Hammond, T. Gleeson, J.M. Deines. 2022. Quantifying Streamflow Depletion from Groundwater Pumping: A Practical Review of Past and Emerging Approaches for Water Management, Journal of the American Water Resources Association, https://onlinelibrary.wiley.com/doi/full/10.1111/1752-1688.12998

 

35. Schreiner-McGraw, A*, H. Ajami.2022. Combined Impacts of Uncertainty in Precipitation and Air Temperature on Simulated Mountain System Recharge from an Integrated Hydrologic Model, Hydrology & Earth System Sciences, https://hess.copernicus.org/preprints/hess-2020-558/

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34. Sullivan, P.L., S. Billings, D. Hirmas, L. Li, X. Zhang, S. Ziegler, K. Murenbeeld, H. Ajami, A. Guthrie, K. Singha, D. Giménez, A. Duro, V. Moreno, A. Flores, A. Cueva,  Koop, E.L. Aronson, H.R. Barnard, S.A. Banwart, R.M. Keen, A. Nemes, N.P. Nikolaidis, J.B. Nippert, D. Richter, D.A. Robinson, K. Sadayappan, L.F.T. de Souza, M. Unruh, H. Wen. 2022. Embracing the Dynamic Nature of Soil Structure: A Paradigm Illuminating the Role of Life in Critical Zones of the Anthropocene, Earth-Science Reviews, https://doi.org/10.1016/j.earscirev.2021.103873.

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33. Cowger, W.C., A. Gray, H. Hapich, J. Osei-Enin, B. Huynh, H. Nogi, S. Singh, S. Brownlee, J. Fong, T. Lok, G. Singer, H. Ajami.2022. Litter Origins, Accumulation Rates, and Hierarchical Composition on Urban Roadsides of the Inland Empire, California, Environmental Research Letters, https://iopscience.iop.org/article/10.1088/1748-9326/ac3c6a/meta 

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2021

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32. Schreiner-McGraw, A.*, H. Ajami.2021. Delayed Response of Groundwater to Multi-year Meteorological Droughts in the Absence of Anthropogenic Management, Journal of Hydrology, https://www.sciencedirect.com/science/article/pii/S0022169421009677?dgcid=coauthor

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2020

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31. Schreiner-McGraw, A.*, H. Ajami.2020. Impact of Uncertainty in Precipitation Forcing Datasets on the Hydrologic Budget of an Integrated Hydrologic Model in Mountainous Terrain, Water Resources Research, https://doi.org/10.1029/2020WR027639

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30. Kim, S., H. Ajami, A. Sharma. 2020. Using Remotely Sensed Information to Improve Vegetation Parameterization in a Semi-distributed Hydrological Model (SMART) for Upland Catchments in Australia, Remote Sensing, http://dx.doi.org/10.3390/rs12183051

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29. Stephens, C. M., L.A. Marshall, F.M. Johnson, L. Lin, L.E. Band, and H. Ajami. 2020. Is Past Variability a Suitable Proxy for Future Change? A Virtual Catchment Experiment, Water Resources Research, 56, https://doi.org/10.1029/2019WR026275

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28. Schreiner-McGraw*, A., E.R. Vivoni, H. Ajami, O.E. Sala, H.L. Throop, D.P.C. Peters.2020. Woody Plant Encroachment has a Larger Impact than Climate Change on Dryland Water Budgets, Scientific Reports, https://doi.org/10.1038/s41598-020-65094-x

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2019

 

27. Schreiner-McGraw*, A., H. Ajami, E. Vivoni.2019. Extreme Weather Events and Transmission Losses in Arid Streams, Environmental Research Letters, doi: 10.1088/1748-9326/ab2949

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26. Tang, Y., L. Marshall, A. Sharma, H. Ajami, D.J. Nott. 2019. Ecohydrologic Error Models for Improved Bayesian Inference in Remotely Sensed Catchments, Water Resources Research, https://doi.org/10.1029/2019WR025055

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25. Fan, Y., M. Clark, D. M. Lawrence, S. Swenson, L. E. Band, S. L. Brantley, P. D. Brooks, W. E. Dietrich, A. Flores, G. Grant, J. W. Kirchner, D. S. Mackay, J. J. McDonnell, P. C. D. Milly, P. L. Sullivan, C. Tague, H. Ajami, N. Chaney, A. Hartmann, P. Hazenberg, J. McNamara, J. Pelletier, J. Perket, E. Rouholahnejad-Freund, T. Wagener, X. Zeng, E. Beighley, J. Buzan, M Huang, B. Livneh, B. P. Mohanty, B. Nijssen, M. Safeeq, C. Shen, W. van Verseveld, J. Volk, D Yamazaki. 2019. Hillslope Hydrology in Global Change Research and Earth System Modeling, Water Resources Research, https://doi.org/10.1029/2018WR023903

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2018

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24. Tang, Y., L. Marshall, A. Sharma, H. Ajami. 2018. Modelling Precipitation Uncertainties in a Multi-objective Bayesian Ecohydrological Setting, Advances in Water Resources, https://doi.org/10.1016/j.advwatres.2018.10.015

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23. Ajami, H., A. Sharma. 2018. Disaggregating Soil Moisture to Finer Spatial Resolutions - A Comparison of Alternatives, Water Resources Research, https://doi.org/10.1029/2018WR022575

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22. Sandoval, E., G. Baldo, N., Núñez, J., Oyarzún, J.P. Fairley, H. Ajami, J.L. Arumí, E. Aguirre, H. Maturana, R. Oyarzún. 2018. Groundwater Recharge Assessment in a Rural, Arid, Mid-mountain Basin in North-Central Chile, Hydrological Sciences Journal, 63(13-14),1873-1889, https://doi.org/10.1080/02626667.2018.1545095

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21. Khan, U., H. Ajami, N.K. Tuteja, A. Sharma, S. Kim. 2018. Catchment Scale Simulations of Soil Moisture Dynamics Using an Equivalent Cross-Section based Hydrological Modelling Approach, Journal of Hydrology. https://doi.org/10.1016/j.jhydrol.2018.07.066

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20. Tang, Y., L. Marshall, A. Sharma, H. Ajami. 2018. A Bayesian Alternative for Multi-objective Ecohydrological Model Specification, Journal of Hydrology, https://doi.org/10.1016/j.jhydrol.2017.07.040

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2017

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19. Niraula, R., T. Meixner, F. Dominguez, N. Bhattarai, M. Rodell, H. Ajami, D. Gochis, C. Castro. 2017. How Might Recharge Change Under Projected Climate Change in the Western US?, Geophysical Research Letters, doi:10.1002/2017GL075421

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18. Niraula, R., T, Meixner, H. Ajami, M. Rodell, D. Gochis, C.L. Castro. 2017. Comparing Potential Recharge Estimates from Three Land Surface Models across the Western US​, Journal of Hydrology, http://dx.doi.org/10.1016/j.jhydrol.2016.12.028

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17. Gemitzi, A., H. Ajami, H. Richnow. 2017. Developing Empirical Monthly Groundwater Recharge Equations based on Modeling and Remote Sensing Data - Modeling Future Groundwater Recharge to Predict Potential Climate Change Impacts​, Journal of Hydrology, http://dx.doi.org/10.1016/j.jhydrol.2017.01.005

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16. Ajami, H., A. Sharma, L.E. Band, J.P. Evans, N. K. Tuteja, G.E. Amirthanathan, M.A. Bari. 2017. On the Non-stationarity of Hydrological Response in Anthropogenically Unaffected Catchments: An Australian Perspective, Hydrology and Earth System Sciences, doi:10.5194/hess-21-281-2017

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2016

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15. Ajami, H., U. Khan, N.K. Tuteja, A. Sharma. 2016. Development of a Computationally Efficient Semi-distributed Hydrologic Modeling Application for Soil Moisture, Lateral Flow and Runoff Simulation, Environmental Modelling & Software. doi: 10.1016/j.envsoft.2016.09.002

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14. Meixner, T., A. Manning, D. Stonestrom, D.M. Allen, H. Ajami, K. Blasch, A. Brookfield, C.L. Castro,  J.F. Clark, D. Gochis, A. Flint, K. Neff, R. Niraula, M. Rodell, B. Scanlon, K. Singha, M. Walvoord. 2016. Implications of Prospective Climate Change for Groundwater Recharge in the Western United States, Journal of Hydrology, doi:10.1016/j.jhydrol.2015.12.027

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13. Naseem, B., H. Ajami, Y. Liu, I. Cordery, A. Sharma. 2016. Multi-objective Assessment of Three Remote Sensing Vegetation Products for Streamflow Prediction in a Conceptual Ecohydrological Model, Journal of Hydrology, doi:10.1016/j.jhydrol.2016.10.038

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2015

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12. Ajami, H., M.F. McCabe, J.P. Evans. 2015. Impacts of Model Initialization on an Integrated Surface Water–Groundwater Model, Hydrological Processes, 29(17):3790-3801, doi: 10.1002/hyp.10478

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11. Naseem, B., H. Ajami, I. Cordery, A. Sharma. 2015. A Multi-objective Assessment of Alternate Conceptual Ecohydrological Models, Journal of Hydrology, 529(3):1221-1234, doi:10.1016/j.jhydrol.2015.08.060

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10. Graham, P., M. Andersen, M.F. McCabe, H. Ajami, A. Baker, I. Acworth. 2015. To What Extent Do Long-Duration High-Volume Dam Releases Influence River-Aquifer Interactions? A Case Study in New South Wales, Australia, Hydrogeology Journal, 23: 319-334, doi: 10.1007/s10040-014-1212-3

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2014

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9. Ajami, H., J.P. Evans, M.F. McCabe, S. Stisen. 2014. Technical Note: Reducing the Spin-up Time of Integrated Surface Water–Groundwater Models, Hydrology and Earth System Sciences, 18, 5169-5179, doi: 10.5194/hess-18-5169-2014

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8. Ajami, H., M.F. McCabe, J.P. Evans, S. Stisen. 2014. Assessing the Impact of Model Spin-up on Surface Water-Groundwater Interactions Using an Integrated Hydrologic Model, Water Resources Research, 50: doi:10.1002/2013WR014258

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7. Khan, U., N. Tuteja, H. Ajami, A. Sharma. 2014. An Equivalent Cross-Sectional Basis for Semi-Distributed Hydrological Modeling, Water Resources Research, 50, doi:10.1002/2013WR014741

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2012

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6. Ajami, H., T. Maddock III, T. Meixner, J.F. Hogan, D.P. Guertin.2012. RIPGIS-NET: A GIS Tool for Riparian Groundwater Evapotranspiration in MODFLOW, Ground Water, 50(1): 154-158, doi:10.1111/j.1745-6584.2011.00809.x

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5. Abramowitz, G., L. Pouyanne, H. Ajami. 2012. On the Information Content of Surface Meteorology for Downward Atmospheric Long-wave Radiation Synthesis, Geophysical Research Letters, 39: doi:10.1029/2011GL050726

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4. Ajami, H., T. Meixner, F. Dominguez, J.F. Hogan, T. Maddock III. 2012. Seasonalizing Mountain System Recharge in Semi-Arid Basins-Climate Change Impacts, Ground Water, 50(4): 585-597, doi:10.1111/j.1745-6584.2011.00881.x

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Prior to 2011

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3. Ajami, H., P.A. Troch, T. Maddock III, T. Meixner, C. Eastoe. 2011. Quantifying Mountain Block Recharge by Means of Catchment-Scale Storage-Discharge Relationship, Water Resources Research, 47, W04504, doi:10.1029/2010WR009598

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2. Ajami, H., T. Meixner, T. Maddock III, J.F. Hogan, D.P. Guertin.2011. Impact of Land-Surface Elevation and Riparian Evapotranspiration Seasonality on Groundwater Budget in MODFLOW Models, Hydrogeology Journal, 19:1181-1188, doi:10.1007/s10040-011-0743-0

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1. Stromberg, J.C., M.G.F. Tluczek, A.F. Hazelton, H. Ajami.2010. A Century of Riparian Forest Expansion Following Extreme Disturbance: Spatio-Temporal Change in Populus/Salix/Tamarix Forests Along the Upper San Pedro River, Arizona, USA, Forest Ecology and Management, 259 (6):1181-1189, doi:10.1016/j.foreco.2010.01.005

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Book Chapters

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1. Ajami, H. 2021. Geohydrology: Global Hydrological Cycle, In: Alderton, David; Elias, Scott A. (eds.) Encyclopedia of Geology, 2nd edition, vol.[6], pp. 393-398. United Kingdom: Academic Press, https://doi.org/10.1016/B978-0-12-409548-9.12387-5

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2. Ajami, H.2021. Geohydrology: Groundwater, In: Alderton, David; Elias, Scott A. (eds.) Encyclopedia of Geology, 2nd edition, vol.[6], pp. 408-415. United Kingdom: Academic Press, https://doi.org/10.1016/B978-0-12-409548-9.12388-7

        

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