Services / Water Resources Engineering
Record Extension and Stochastic Hydrology
The levels of the Nile River have been measured for more than 5,000 years and have been written down for over 13 centuries. But, in most of the world water resources planners must rely on an instrumental record of streamflows that may be only a few decades in length. With our increasing understanding of large-scale climatic cycles we now know that these short records may not be representative of long-term hydrologic conditions, and in particular may not include examples of important flood or drought events. Whether human-caused or not, the burden of evidence now indicates that our climate is changing, so the future may not exhibit the characteristics of hydrologic conditions of the recent past.
Record extension techniques allow water supply managers to evaluate the reliability of their systems in broader hydrological contexts. Stochastic hydrologic techniques allow for the construction of synthetic records of arbitrary length that are consistent with observed conditions, as well as synthetic records that are consistent with different climate change hypotheses, and which incorporate the uncertainty in those hypotheses.
Hydrosphere has developed record-extension techniques that are surprisingly cost-effective and that rely on a water supply manager's own models and data sets. These resampling techniques have been used to extend records over historical periods where incomplete data exist and over prehistoric periods using tree-ring records. We have also applied these non-parametric resampling techniques to synthesis of hydrologic records and we have used "traditional" parametric techniques for the same purpose.
- Our record extension services include:
- Data collection and analysis
- Parametric and non-parametric statistical analysis
- Spatial and temporal downscaling techniques
- Downscaling of global circulation model (GCM) output
- Resampling techniques
- Monte Carlo simulation techniques
- Statistical analysis and presentation of model results
- Risk and reliability assessment