Development of Synthetic Hydrologic Records for Modeling Shasta Temperature Management

Lynker was tasked with developing synthetic streamflow records to be used for input to the National Oceanic and Atmospheric Administration (NOAA) National Marine Fisheries Service (NMFS) Winter-run Life Cycle Model (WRLCM). A synthetic record of annual flow for the Sacramento River Index is needed for this application in order to construct a hydrology dataset that has a long period of record (i.e., 100 years) while also using a limited subset of the historical data period (1970-2014 – model calibration period).

Lynker implemented a well-documented Markov chain stochastic modeling approach to develop an ensemble of resequenced hydrology records. This stochastic hydrology method uses the empirical distribution of the historical data as a basis for simulating ‘new’ sets of flows using specific random or ‘probabilistic’ analyses. This results in sequences of data that are different from but consistent with the historical record.

Lynker performed a detailed analysis of the drought characteristics for each of the traces, and this report provides a summary of the methods and recommendations as to which simulated traces meet the criteria of ‘multi-year drought events consistent with historical conditions’ and which simulated traces meet the criteria of ‘more frequent multi-year drought events’.