NEW MEXICO RIO GRANDE WATER OPERATIONS MODELING: CREATING A SYNTHETIC FLOW SEQUENCE REPRESENTATIVE OF REGIONAL PALEO-HYDROLOGY FOR ALTERNATIVES ANALYSIS

A planning model version of the Upper Rio Grande Water Operations Model (URGWOM) is currently in development for use in analysis of water operations alternatives as part of an EIS being conducted under NEPA guidelines. One of the key issues in the model development has been determining how to use available data to drive the model while simulating “representative” average, drought and wet-period events.

S.S. Papadopulos & Associates was asked to create a “typical” 40-year sequence, representative of a broad range of climatic conditions, to represent hydrologic inputs for the URGWOM planning model. The “pool” of available data for construction of this sequence is restricted to the period from 1975 to 1999. Our findings indicate 45% of the years between 1975 and 1999 represent “very wet” conditions for the Middle Rio Grande valley, and the Pacific Decadal Oscillation appears to significantly impact regional hydrology. Tree ring climate reconstructions were used to “normalize” the recent record to the long-term record and to determine the relative proportions and lengths of drought, average and wet conditions.