Managing Water Resources in the West Under Conditions of Climate Uncertainty A Proceedings (1991) / Chapter Skim
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14. Some Aspects of Hydrologic Variability
14. Some Aspects of Hydrologic Variability
Pages 275-280
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From page 275... ...
The time series associated with such "Hurst like" measure resemble remarkably the sequences now considered in "alternative scenarios" resulting from "climate change." This means that the tools of stochastic hydrology that were developed over a 20-year period starting in the mid-1960s might be useful for assessing water resource system reliability under variable climates. If the annual scale is considered, both the range of what could be experiences in any year (the marginal probability distribution)
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From page 276... ...
When viewed in a larger time frame, it is clear that there is no trend but the series indicates different types of variability-extreme swings from low to high as well as an apparent increasing trend superposed on extreme swings. Tree-ring series are being used increasingly in regression equations as surrogates of streamflow that occurred before stream gauges were installed with the objective of providing an equivalent long historical record of "streamflow that might have occurred." 200 X 160 3 :t 3 O 120 V o 80 40 o 0 25 50 75 100 TIME, YEARS FIGURE 14.1 Annual tree ring index for Limber pine at Dell, Montana showing the range of variability that can be observed in a geophysical time series.
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From page 277... ...
The measure of long-term persistence, the Hurst coefficient, is approximately 0.8 and the lag-one correlation coefficient, a measure of shorter-term persistence, is 0.4. This is a highly persistent river flow situation with prolonged excursions from the mean level of both high and low flow with associated swings in flow volume from year to year.
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From page 278... ...
The cumulative probability distribution of needed storage size for a particular physical demand was determined by routing 1000 (independent) stochastically generated sequences, each having length 40 years through a mass curve analysis (sequent peak algorithm, Fiering, 1967)
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From page 280... ...
and disaggregation models for annual streamflow generation. Water Resources Res.
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