Impact of Historical Temperature Increase on California State Water Project and Central Valley Project Planning Studies: The Question on the Non-stationarity of the Historical Hydrologic Record Due to Climate Change
Abstract
The observed historical climate and stream flow records for the past 90 plus years play a key role in the facilities and operational planning of the State Water Project (SWP) and Central Valley Project (CVP)—key state and federal water infrastructure located in the Central Valley of California. The temperature record in the past 100 years or so, however, show an increasing trend, especially after 1970s', thereby raising the doubt on the validity of any statistical assessment of non-stationary hydrologic and meteorological data. Does this (mostly) increasing trend in historical temperature have any significant impact on our existing water resources facilities and operations in general or specifically in the case of SWP/CVP planning in the Central Valley? Is it necessary to find means to first convert the non-stationary historical data to stationary, then conduct traditional planning studies? In this study, an approach is presented to do exactly that—convert the historical data into stationary form by detrending the historical temperature, then apply traditional planning techniques to assess probabilistic response of the system. Results of this analysis is then compared with those from without the conversion. In this research, a rainfall-runoff model called Soil & Water Assessment Tool (SWAT) was run twice for rim watersheds, one with the historical temperature and another with the detrended historical temperature to the current (2015) level of warming. The flow differences between the two runs represent the flow change due to the historical temperature increase. These flow changes are added to the historical flow to represent detrended flow. The Central Valley floor water demands were also re-generated with the detrended historical temperature. The water resources planning model widely used in California (CalSim 3.0) was utilized to simulate the SWP/CVP operations with detrended rim inflows and water demands. The result indicates that the historical temperature increases for the last century does not seem to have a significant impact on the existing SWP/CVP planning studies based on the historical climate record.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H11Q1777Y
- Keywords:
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- 1807 Climate impacts;
- HYDROLOGY;
- 1880 Water management;
- HYDROLOGY;
- 1918 Decision analysis;
- INFORMATICS;
- 6309 Decision making under uncertainty;
- POLICY SCIENCES & PUBLIC ISSUES