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Chen, M. and Herman, J. Detection time for nonstationary reservoir system performance driven by climate and land use change. ASCE Journal of Water Resources Planning and Management, 150 (4). 2024.

Detect changes in water supply and flood performance outside the envelope of natural variability, and attribute the timing of these detections to uncertain drivers. Train a logistic regression classifier to predict future detections given recent observations. [Github].

Herman, J. Seasonal Forecast of the California Water Price Index. ASCE Journal of Water Resources Planning and Management, 150 (1). 2024.

Principal component regression to predict the forward six-month average of the NQH2O index based on reservoir storage anomalies and ensemble inflow forecasts. A threshold-based hedging strategy uses the forecast model to reduce the risk of price increases following allocation announcements from SWP/CVP.


Bryant, B., Maurer, T., Saksa, P., Herman, J., Wilson, K., and Smith, E. Exploring Interacting Effects of Forest Restoration on Wildfire Risk, Hydropower, and Environmental Flows. Sustainability 15 (11549). 2023.

Models the impact of forest restoration on wildfire behavior, hydropower generation, and environmental flows in the Middle Fork American River Basin, California. [Github]

Steinschneider, S., Herman, J., Kucharski, J., Abellera, M., and Ruggiero, P. Uncertainty decomposition to understand the influence of water systems model error in climate vulnerability assessments. Water Resources Research, 59 (1). 2023.

Method to investigate whether the total uncertainty in output metrics is primarily attributable to the climate ensemble or to the systems model itself, combining time series error models with time-varying Sobol sensitivity analysis. [Github]


Molla, N., DeIonno, J., Gross, T., and Herman, J. Governing Change: A Dynamical Systems Approach to Understanding the Stability of Environmental Governance. Earth System Dynamics, 13 (4). 2022.

Generalized modeling framework to understand the structural features impacting the stability of resource governance systems, including the heterogeneity and connectivity of actors. [Github]

Torres-Rojas, L., Vergopolan, N., Herman, J., and Chaney, N. Toward an optimal representation of sub-grid heterogeneity in land surface models. Water Resources Research, 58 (12). 2022.

Determines optimal tile configuration for a target level of spatially distributed model complexity as a multi-objective problem.

Zhang, C., Brodeur, Z., Steinschneider, S., and Herman, J. Leveraging spatial patterns in precipitation forecasts using deep learning to support regional water management. Water Resources Research, 58 (9). 2022.

Deep learning models trained on images of GEFS precipitation forecasts to classify the occurrence of heavy precipitation for a target region. Analyzes network activation across lead times. [Github]

Wrzesien, M., Pavelsky, T., Sobolowski, S., Huning, L., Cohen, J., and Herman, J. Tracking the impacts of precipitation phase changes through the hydrologic cycle in snowy regions: From precipitation to reservoir storage. Frontiers in Earth Science, 10. 2022.

Investigates projected patterns in changing precipitation phase for mountain areas of the western United States over the 21st century and how shifts from snow to rain may impact runoff and reservoir storage.

Srikrishnan, V., Lafferty, D., Wong, T., Lamontagne, J., Quinn, J., Sharma, S., Molla, N., Herman, J., Sriver, R., Morris, J., and Lee, B. Uncertainty analysis in multi-sector systems: Considerations for risk analysis, projection, and planning for complex systems. Earth’s Future, 10 (8). 2022.

Reviews challenges to the goal of characterizing, attributing, and quantifying uncertainty in multi-sector systems, including inference and model calibration, simulation, and sensitivity analysis.

Mautner, M., Foglia, L., and Herman, J. Coupled effects of observation and parameter uncertainty on urban groundwater infrastructure decisions. Hydrology and Earth System Sciences, 26 (5), 1319-1340. 2022.

Determines the importance of observation choice and parameter values on aquifer management objectives when controlling for model error, and compares how the relative performance of management alternatives varies when exposed to endogenous uncertainties. [Github]

Iwanaga, T., Usher, W. and Herman, J. Toward SALib 2.0: Advancing the accessibility and interpretability of global sensitivity analyses Socio-Environmental Systems Modelling, 4, 18155. 2022.

Describes recent and planned updates to the SALib package for global sensitivity analysis, focused on simplifying applications, interpreting results, and fostering a community of practice.

Malek, K., Reed, P., Zeff, H., Hamilton, A., Wrzesien, M., Holtzman, N., Steinschneider, S., Herman, J., and Pavelsky, T. Bias Correction of Hydrologic Projections Strongly Impacts Inferred Climate Vulnerabilities in Institutionally Complex Water Systems. ASCE Journal of Water Resources Planning and Management 148 (1). 2022.

Investigates how model projection errors influence assessments of water availability and financial stability for irrigation districts in California.


Cohen, J. and Herman, J. Dynamic adaptation of water resources systems under uncertainty by learning policy structure and indicators. Water Resources Research 57 (11). 2021. EOS Editor’s Highlight.

Framework for dynamic adaptation of water resources systems under climate and land use uncertainty by designing and testing policies that combine relevant indicators, actions, and thresholds in a flexible structure. [Github].

Cohen, J., Zeff, H., and Herman, J. How do the properties of training scenarios influence the robustness of reservoir operating policies to climate uncertainty?. Environmental Modelling and Software 141 (105047). 2021.

Investigates the relationship between scenario properties (annual runoff, snowpack, and baseline regret) and the ability of policies to generalize out of sample. [Github].

Zeff, H., Hamilton, A., Malek, K., Herman, J., Cohen, J., Medellin-Azuara, J., Reed, P., and Characklis, G. California’s Food-Energy-Water System: An Open Source Simulation Model of Adaptive Surface and Groundwater Management in the Central Valley. Environmental Modelling and Software 141 (105052). 2021.

CALFEWS simulation model connecting statewide inter-basin transfers with conjunctive water management strategies at the scale of irrigation and water storage districts. [Github].

Molla, N., DeIonno, J., and Herman, J. Dynamics of resilience-equity interactions in resource-based communities. Nature Communications: Earth & Environment 2 (27). 2021.

Dynamical systems model of asymmetric resource access in resource-based communities linking industrial resource degradation, community well-being, and migration in response to economic and resource conditions. [Github].

Ekblad, L. and Herman, J. Toward data-driven generation and evaluation of model structure for integrated representations of human behavior in water resources systems. Water Resources Research 57 (2). 2021.

Automated generation of model structure to describe human behavior in water systems using symbolic regression. Evaluation along performance-complexity tradeoff, and sensitivity analysis of resulting model structures. [Github].

Liu, Z., Herman, J., Huang, G., Kadir, T., and Dahlke, H. Identifying climate change impacts on surface water supply in the southern Central Valley, California. Science of the Total Environment 759 (143429). 2021.

Multivariate calibration of SWAT models for the Tulare Basin, California to evaluate changes in runoff timing due to current and future snowpack decline.


Cohen, J., Zeff, H., and Herman, J. Adaptation of multi-objective reservoir operations to snowpack decline in the Western United States, Journal of Water Resources Planning and Management 146 (12). 2020. (*Editor’s Choice Collection)

Adaptations by parameterizing the structure of existing policies using a dynamic flood control rule curve and revised snowpack-to-streamflow forecasting methods. [Github].

Brodeur, Z., Herman, J., and Steinschneider, S. Bootstrap aggregation and cross-validation methods to reduce overfitting in reservoir control policy search. Water Resources Research 56 (8). 2020.

Extensions of bagging and cross-validation techniques for policy search problems using streamflow resamples from the paleo record.

Robinson, B., Cohen, J., and Herman, J. Detecting early warning signals of long-term water supply vulnerability using machine learning, Environmental Modelling and Software 131 (104781). 2020.

Dynamic classification of the occurrence of water supply vulnerability to climate change, represented by the long-term moving average of reliability falling below a threshold. [Github].

Mautner, M., Foglia, L., Herrera, G., Galán, R., and Herman, J. Urban growth and groundwater sustainability: evaluating spatially distributed recharge alternatives in the Mexico City Metropolitan Area, Journal of Hydrology 586 (124909). 2020.

Comparing managed recharge alternatives to reduce the effect of historical overdraft using a physically-based groundwater model.

Herman, J., Quinn, J., Steinschneider, S., Giuliani, M., and Fletcher, S. Climate adaptation as a control problem: Review and perspectives on dynamic water resources planning under uncertainty , Water Resources Research 56 (2). 2020.

Review article framing dynamic adaptation to climate change as an optimal control problem. Discussion of challenges that arise due to multiple sources of uncertainty.

Holtzman, N., Pavelsky, T., Cohen, J., Wrzesien, M., and Herman, J. Tailoring WRF and Noah-MP to improve process representation of Sierra Nevada runoff: Diagnostic evaluation and applications, Journal of Advances in Modeling Earth Systems 12 (3). 2020.

Modifying process representation in the coupled WRF/Noah-MP model to improve hydrologic simulation upstream of California reservoirs.

Singh, L., Whittecar, W., DiPrinzio, M., Herman, J., Ferringer, M., and Reed, P. Low cost satellite constellations for nearly continuous global coverage, Nature Communications 11 (200). 2020.

Optimization-based design of satellite constellations for near-continuous global coverage.


Rankings of most sensitive parameters
Reinecke, R., Foglia, L., Mehl, S., Herman, J., Wachholz, A., Trautmann, T., and Döll, P. Spatially distributed sensitivity of simulated global groundwater heads and flows to hydraulic conductivity, groundwater recharge and surface water body parameterization, Hydrology and Earth System Sciences, (23) 4561–4582. 2019.

Sensitivity analysis of a global groundwater model using Method of Morris.

Perennial crop distribution in the Central Valley, 2016
Mall, N. and Herman., J. Water shortage risks from perennial crop expansion in California’s Central Valley, Environmental Research Letters (14) 104014. 2019.

Analysis of perennial crop data and implications for water supply derived from pesticide permits over the period 1974-2016. [Github].

CDF distance metric between prior-posterior soil parameters
Chaney, N., Minasny, B., Herman, J., Nauman, T., Brungard, C., Morgan, C., McBratney, A., Wood, E. and Yimam, Y.T. POLARIS soil properties: 30-meter probabilistic maps of soil properties over the contiguous United States, Water Resources Research, 55 (4), 2916-2938. 2019.

High-resolution soil dataset with reduced uncertainty compared to standard prior distributions used in land surface model calibration.

Robinson, B. and Herman, J. A framework for testing dynamic classification of vulnerable scenarios in ensemble water supply projections, Climatic Change, 152 (3-4), 431-448. 2019.

A statistical testing approach for threshold-based classifiers of vulnerable scenarios in long-term streamflow projections. [Github].


Giuliani, M. and Herman, J. “Modeling the behavior of water reservoir operators via eigenbehavior analysis”, Advances in Water Resources, 122, 228-237. 2018.

Clustering California reservoirs based on typical behavioral profiles.

Nayak, M., Herman, J., and Steinschneider, S. “Balancing flood risk and water supply in California: Policy search integrating short‐term forecast ensembles with conjunctive use”, Water Resources Research, 54 (10), 7557-7576. 2018.

Extension of policy tree optimization method using synthetic ensembles of streamflow forecasts for reservoir control, including groundwater banking.

Dogan, M., Fefer, M., Herman, J., Hart, Q., Merz, J., Medellin-Azuara, J., and Lund, J. “An open-source Python implementation of California’s hydroeconomic optimization model”, Environmental Modelling & Software, 108, 8-13. 2018.

Short communication describing open-source version of the CALVIN model with LP solver performance benchmarks. [Github].

Hui, R., Herman, J., Lund, J., and Madani, K. “Adaptive water infrastructure planning for nonstationary hydrology”, Advances in Water Resources, 118, 83-94. 2018.

Adaptive levee planning with nonstationary flood risk, using stochastic dynamic programming.

Clarkin, T., Raseman, W., Kasprzyk, J., and Herman, J. “Diagnostic assessment of preference constraints for simulation-optimization in water resources”, Journal of Water Resources Planning and Management, 144 (8), 2018.

Impact of preference constraints (i.e., optional constraints on objective values) on the performance of multi-objective evolutionary algorithms.

Giuliani, M., Quinn, J., Herman, J., Castelletti, A., and Reed, P., “Scalable multi-objective control for large scale water resources systems under uncertainty”, IEEE Transactions on Control Systems Technology, 26(4), 1492-1499, 2018.

Policy search for multi-reservoir systems using a hierarchical parallelization scheme, using both deterministic and stochastic hydrology.

Herman, J. and Giuliani, M. “Policy tree optimization for threshold-based water resources management over multiple timescales”, Environmental Modelling and Software, 99, 39-51, 2018.

Binary tree policy search for control of dynamic systems. Uses a heuristic simulation-optimization approach. [Github].


Adams, L., Lund, J., Moyle, P., Quiñones, R., Herman, J., and O’Rear, T. “Environmental hedging: Theory and method for reconciled reservoir operations for downstream ecology and water supply”, Water Resources Research, 53, doi:10.1002/2016WR020128, 2017.

An approach for reservoir operation to incorporate downstream biological objectives without sacrificing water supply reliability. The method is applied for fall-run Chinook salmon in the Lower American River.

Rosenberg, D., Babbar-Sebens, M., Root, E., Herman, J., Mirchi, A., Giacomoni, M., Kasprzyk, J., Madani, K., Ford, D., Basdekas, L. “Toward more integrated formal education and practice in water resources systems analysis”, Journal of Water Resources Planning and Management, 143 (12), 2017.

An editorial based on the results of practitioner interviews and analyzing course syllabi from the systems analysis field.

Trindade, B., Reed, P., Herman, J., Zeff, H., and Characklis, G., “Reducing regional drought vulnerabilities and multi-city robustness conflicts using many-objective optimization under deep uncertainty”, Advances in Water Resources, 104, 195-209, 2017.

Optimization of decision alternatives across an ensemble of deeply uncertain scenarios, rather than optimizing to historical observations and then simulating the ensemble.

Herman, J. and Usher, W. “SALib: An open-source Python library for sensitivity analysis”, Journal of Open Source Software, 2(9), 2017.

Implementations of the Sobol, Morris, FAST, and Delta methods, among others. [Github]


Chaney, N., Herman, J., Ek, M., and Wood, E., “Deriving global parameter estimates for the Noah land surface model using FLUXNET and machine learning”, Journal of Geophysical Research: Atmospheres, 121(22), 13218-13235, 2016.

Estimating the mean and variance of global parameter values using extra-trees regression, after first reducing the dimension of the parameter space using sensitivity analysis.

Zeff, H., Herman, J., Reed, P., and Characklis, G., “Cooperative drought adaptation: Integrating infrastructure development, conservation, and water transfers into adaptive policy pathways”, Water Resources Research, 52(9), 7327-7346, 2016. (*INFORMS ENRE Best Publication in Natural Resources, 2019)

Multi-objective optimization for urban water utilities combining long-term infrastructure development with short-term conservation options, where decisions are triggered by thresholds of a risk metric.

Herman, J., Zeff, H., Lamontagne, J., Reed, P., and Characklis, G., “Synthetic drought scenario generation to support bottom-up water supply vulnerability assessments”, Journal of Water Resources Planning and Management, 142(11), 04016050, 2016.

Modifies a synthetic streamflow generation technique to allow user-defined frequency and severity of droughts while preserving autocorrelation and spatial correlation. [Github].

Zatarain-Salazar, J., Reed, P., Herman, J., Giuliani, M., and Castelletti, A. “A diagnostic assessment of evolutionary algorithms for multi-objective reservoir control”, Advances in Water Resources, 92, 172-185, 2016.

A comparison of multi-objective optimization methods for a single-reservoir direct policy search problem. Uses MOEAFramework and Borg MOEA.


Hadka, D., Herman, J., Reed, P., and Keller, K. “An Open Source Framework for Many-Objective Robust Decision Making”, Environmental Modelling & Software, 74, 114-129, 2015.

The OpenMORDM library for decision making under deep uncertainty. [Github]

Chaney, N.W., Herman, J.D., Reed, P.M., and Wood, E.F., “Flood and Drought Hydrologic Monitoring: The Role of Model Parameter Uncertainty”, Hydrology and Earth System Sciences, v19, 3239-3251, 2015.

Large-scale ensemble evaluation of VIC model parameters on a global grid. Constraining ensemble members with observed data and calculating parameter sensitivity using the CDF distance metric.

Reed, P. M., Chaney, N.W., Herman, J.D., Ferringer, M.P., and Wood, E. F., “Internationally Coordinated Multi-Mission Planning Is Now Critical to Sustain the Space-based Rainfall Observations Needed for Managing Floods Globally”, Environmental Research Letters, 10, (024010), 2015.

Analyzing and optimizing coverage of satellite constellations for rainfall observation.

Herman, J.D., Reed, P.M., Zeff, H.B., and Characklis, G., “How should robustness be defined for water systems planning under change?”, Journal of Water Resources Planning and Management, 141(10), 04015012, 2015. (*Quentin Martin Best Practice-Oriented Paper, 2016)

A review of frameworks for decision making under deep uncertainty, where the probabilities of future scenarios are difficult to quantify.


Herman, J.D., Zeff, H.B., Reed, P.M., and Characklis, G., “Beyond Optimality: Multi-stakeholder robustness tradeoffs for regional water portfolio planning under deep uncertainty”, Water Resources Research, 50, 7692–7713, 2014.

Given a set of multi-objective solutions optimized under historical conditions, this study subjects them to a range of hydrologic and economic uncertainties to identify the most robust solutions.

Zeff, H.B., Kasprzyk, J.R., Herman, J.D., Reed, P.M., and Characklis, G., “Navigating Financial and Supply Reliability Tradeoffs in Regional Drought Portfolios”, Water Resources Research, 50, 4906-4903, 2014.

Multi-objective portfolios of water conservation and transfer options for urban water utilities to maintain supply reliability and reduce financial impacts of drought.

Giuliani, M., Herman, J.D., Castelletti, A., and Reed, P.M., “Many-objective reservoir policy identification and refinement to reduce policy inertia and myopia in water management.”, Water Resources Research, 50, 3355–3377, 2014.

Identifying an existing reservoir operating policy from historical data using a network of radial basis functions, and re-optimizing the policies for multiple objectives across an ensemble of synthetic streamflows.

Herman, J.D., Reed, P.M., Kollat, J., and Wagener, T., “From maps to movies: High resolution time-varying sensitivity analysis for spatially distributed watershed models.”, Hydrology and Earth Systems Sciences, v17, 5109-5125, 2013.

Parameter sensitivity computed at a three-hour timestep and compared to aggregate event-scale sensitivity to improve process understanding of a spatially distributed hydrologic model.

Herman, J.D., Reed, P.M., Kollat, J., and Wagener, T., “Technical Note: Method of Morris effectively reduces the computational demands of global sensitivity analysis for distributed watershed models.”, Hydrology and Earth Systems Sciences, v17, 2893-2903, 2013.

For a spatially distributed watershed model, we show that the Morris method can produce parameter sensitivity values and rankings similar to the Sobol method, with significantly reduced computation time.

Herman, J.D., Reed, P.M., and Wagener, T., “Time-varying sensitivity analysis clarifies the effects of watershed model formulation on model behavior.” Water Resources Research, v49, n3, 1400-1414, 2013.

Sobol sensitivity analysis of three hydrologic models (Hymod, HBV, SAC-SMA) at monthly and annual timesteps, performed across a hydroclimatic gradient of 12 watersheds in the US.

Reed, P.M., Hadka, D., Herman, J., Kasprzyk, J., and Kollat, J., “Evolutionary Multiobjective Optimization in Water Resources: The Past, Present, and Future.” (Invited Submission to 35th Anniversary Special Issue), Advances in Water Resources, v51, 438-456, 2013.

A comprehensive diagnostic comparison of state-of-the-art optimization methods for multi-objective problems, using three real-world case studies: hydrologic model calibration, water supply planning, and groundwater monitoring. Uses MOEAFramework and Borg MOEA.