Douglas P. Boyle

Toward improved calibration of hydrologic models: Combining the strengths of manual and automatic methods

Automatic methods for model calibration seek to take advantage of the speed and power of digital computers, while being objective and relatively easy to implement. However, they do not provide parameter estimates and hydrograph simulations that are considered acceptable by the hydrologists responsible for operational forecasting and have therefore not entered into widespread use. In contrast, the manual approach which has been developed and refined over the years to result in excellent model calibrations is complicated and highly labor-intensive, and the expertise acquired by one individual with a specific model is not easily transferred to another person (or model). In this paper, we propose a hybrid approach that combines the strengths of each. A multicriteria formulation is used to “model” the evaluation techniques and strategies used in manual calibration, and the resulting optimization problem is solved by means of a computerized algorithm. The new approach provides a stronger test of model performance than methods that use a single overall statistic to aggregate model errors over a large range of hydrologie behaviors. The power of the new approach is illustrated by means of a case study using the Sacramento Soil Moisture Accounting model.

Toward improved streamflow forecasts: value of semidistributed modeling

The focus of this study is to assess the performance improvements of semidistributed applications of the U.S. National Weather Service Sacramento Soil Moisture Accounting model on a watershed using radar-based remotely sensed precipitation data. Specifically, performance comparisons are made within an automated multicriteria calibration framework to evaluate the benefit of “spatial distribution” of the model input (precipitation), structural components (soil moisture and streamflow routing computations), and surface characteristics (parameters). A comparison of these results is made with those obtained through manual calibration. Results indicate that for the study watershed, there are performance improvements associated with semidistributed model applications when the watershed is partitioned into three subwatersheds; however, no additional benefit is gained from increasing the number of subwatersheds from three to eight. Improvements in model performance are demonstrably related to the spatial distribution of the model input and streamflow routing. Surprisingly, there is no improvement associated with the distribution of the surface characteristics (model parameters).

Placing the 2012–2015 California-Nevada drought into a paleoclimatic context: Insights from Walker Lake, California-Nevada, USA

Assessing regional hydrologic responses to past climate changes can offer a guide for how water resources might respond to ongoing and future climate change. Here we employed a coupled water balance and lake evaporation model to examine Walker Lake behaviors during the Medieval Climate Anomaly (MCA), a time of documented hydroclimatic extremes. Together, a 14C-based shoreline elevation chronology, submerged subfossil tree stumps in the West Walker River, and regional paleoproxy evidence indicate a ~50 year pluvial episode that bridged two 140+ year droughts. We developed estimates of MCA climates to examine the transient lake behavior and evaluate watershed responses to climate change. Our findings suggest the importance of decadal climate persistence to elicit large lake-level fluctuations. We also simulated the current 2012–2015 California-Nevada drought and found that the current drought exceeds MCA droughts in mean severity but not duration.

Modeling: A basis for linking policy to adaptive water management

Foreword John Dantonio 1. Introduction Part 1: Setting the Context for Water Management in New Mexico 2. Modeling: A Basis for Linking Policy to Adaptive Water Management 3. Water Resources in New Mexico 4. Climate and Drought in New Mexico Part 2: The Historical, Legal, and Institutional Setting of Water Policy in New Mexico 5. The Tangled History of New Mexico Water Law 6. The Historical Role of Acequias and Agriculture in New Mexico 7. Water Rights in New Mexico 8. Its Not Just Our Water: Shared Governance for New Mexicos Water Part 3: The Economics of Water Management in New Mexico 9. Water Markets in New Mexico 10. The Pricing and Conservation of Water in Urban Areas Part 4: Contemporary Challenges in Water Management 11. Domestic Wells in New Mexico 12. Impacts of Endangered Species Protection on Water Management, Allocation, and Use in New Mexico: Lessons Learned and Uncertainties about the Future 13. Science and Management Needs Related to the Sustainability of Riparian Ecosystems Part 5: Conclusion 14. Issues for the Future

Determining atmospheric dust concentrations during strong flow perturbations using a digital-optical technique

Dust emissions due to low-level flight of a helicopter are studied as part of the Integrated Desert Terrain Forecasting for Military Operations project. Atmospheric concentrations of PM10 were measured at different heights downwind of the helicopter flight path. Digital video images captured the entrainment and dispersion of the dust plume formed by the wake of the helicopter during each pass down the flight course. The video data are analyzed to relate the dust plume strength to degradation of local visibility. A strong relationship between color changes/standard deviations and plume strength is found. This relationship is used to develop an algorithm that can determine local visibility degradation due to local PM10 concentrations around a helicopter. This algorithm can be combined with concentration output data from an atmospheric dispersion model to simulate visibility in a helicopter simulator.