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Georgia Water Resources Conference

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Author: Rasmussen, Todd C. × Start date: 2010 × End date: 2013 ×

Publication Search Results

Now showing 1 - 4 of 4
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    Declaring Drought for Effective Water Management
    (Georgia Institute of Technology, 2013-04) McKay, S. Kyle ; Rasmussen, Todd C.
    Water managers are tasked with resolving conflicts between freshwater resource uses, which range from municipal water supply, to recreation, and to sustaining aquatic ecosystem integrity. Further complicating management, hydrologic processes experience numerous sources of periodic, quasi-periodic, and episodic variation. Water allocation tradeoffs are often most complex and contentious when availability is low. Drought is a “recurring extreme climatic event over land characterized by below-normal precipitation over a period of months to years” (Dai 2011). Water managers often apply indicators of climatologic and hydrologic conditions to identify when drought conditions are reached (e.g., Palmer Drought Severity Index, streamflow, respectively). These indicators inform drought declarations, with associated drought responses such as watering restrictions. Herein, we suggest techniques for predicting and declaring oncoming drought to improve the accuracy of drought declarations. We hypothesize that drought indicators in preceding months are predictive of future drought levels. Specifically, we develop predictive models using the Palmer Hydrologic Drought Index, a common drought indicator. We then demonstrate the utility of our model for drought declarations for the Middle Oconee River near Athens.
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    Coupling Tritium Release Data with Remotely Sensed Precipitation Data to Assess Model Uncertainties
    (Georgia Institute of Technology, 2011-04) Avant, Brian K. ; Ignatius, Amber R. ; Rasmussen, Todd C. ; Grundstein, Andrew ; Mote, Thomas L. ; Shepherd, J. Marshall
    An accidental tritium release (570 L, 210 TBq) from the K-Reactor at the Savannah River Site (South Carolina, USA) occurred between December 22- 25, 1991. Observed tritium concentrations in rivers and streams, as well as in the coastal estuary, are used to calibrate a hydrologic flow and transport model, BASINS 4.0 (Better Assessment Science Integrating Point and Non- Point Sources) environmental analysis system and the HSPF hydrologic model. The model is used to investigate complex hydrometeorological and source attribution problems. Both source and meteorologic input uncertainties are evaluated with respect to model predictions. Meteorological inputs include ground-based rain gauges supple-mented with and several NASA products including TRMM 3B42, TRMM 3B42RT, and MERRA (Modern Era Retrospective-Analysis for Research and Applications) reanalysis data. Model parameter uncertainties are evaluated using PEST (Model-Independent Parameter Estimation and Uncertainty Analysis) and coupled to meteorologic uncertainties to provide bounding estimates of model accuracy.
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    Beyond Correlation: the Search for Causal Relationships Between Flow Percentiles and Watershed Variables
    (Georgia Institute of Technology, 2011-04) Ssegane, Herbert ; Tollner, E. W. ; Mohamoud, Yusuf ; Rasmussen, Todd C. ; Dowd, John F.
    The study explored use of causal feature selection algorithms to select dominant watershed variables that drive high, medium, and low flows. A two step approach was implemented. The first step minimized variable redundancy by examining variable relevance, variable redundancy, and conditional relevance of variable pairs whose correlation was greater than 0.9. The second step used six algorithms that seek to reconstruct a Bayesian network structure around a target variable for each flow percentile. Nineteen (19) flow percentiles were used to characterize high, medium, and low flow conditions of 26 Piedmont watersheds in the Mid-Atlantic. The algorithms included: (1) Grow-Shrink (GS); (2) interleaved-Incremental Association Markov Boundary (interIAMB) (3) Incremental Association Markov Boundary with Peter-Clark (IAMBnPC); (4) Local Causal Discovery (LCD2); (5) HITON-PC; and (6) HITON-MB. A new method was developed to quantify the reliability of each algorithm and its performance was compared to existing reliability methods. The effect of the initial number of variables on the final variable set selected by each algorithm was tested. Fusion of the algorithms was used to determine the overall dominant features for each flow percentile.
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    Hydrologic Impacts of Energy Production
    (Georgia Institute of Technology, 2011-04) Rasmussen, Todd C.
    Global future energy requirements will likely require substantial investments in power production facilities. Both hydro- and thermo-electric power production require water as part of their operations, some of which is water consumptive (i.e., water is lost by evaporation as part of the cooling or storage process), while other water use is nonconsumptive (i.e., water is returned to the source). Both consumptive and non-consumptive water uses may affect water quantity and quality, such as increased thermal load, decreased hydrologic connectivity, and alteration of natural flow regimes. This presentation discusses the main features of the water-energy nexus with the goal of establishing a framework for evaluating the hydrologic impacts of energy production.