The Impacts of Climate Change and Variability on Water Resources in a Semi Arid Region in Mexico: The Rio Yaqui-Basin.
Andrea Muñoz-Hernández Alex S. Mayer
Department of Civil and Environmental Engineering
Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, United States
This work consists of determining the impacts of climate change and variability on precipitation and reservoir storage in the Yaqui Basin. The basin is classified as a semi-arid climate with an average rainfall of 527 mm per year. It consists of roughly 72,000 square kilometers of land, primarily in northwest Mexico. The water to meet all demands comes from three reservoirs in series constructed along the river. Agriculture is the main user of water in the basin.
A rainfall-runoff model has been created and calibrated and integrated into a node link network that includes reservoir storage and extractions by users. Precipitation data was interpolated on a monthly basis over a thirty three year time span with data collected from weather stations throughout the basin. Distributions of static runoff coefficients were generated based on published regional maps (INEGI). Using GIS the product of the precipitation and runoff coefficients were determined and a monthly hypothetical runoff was calculated. This monthly runoff data was merged into three seasons. This GIS based seasonal runoff was further adjusted by calibrating it against thirty three years of seasonal inflow data collected at each reservoir. The calibration is done by fitting a linear model relating the GIS based runoff with the reservoir inflows.
Three different approaches for generating future precipitation scenarios based on a 30-year planning period were applied. The first approach involved repeating the 1970-2000 historical precipitation record. The second approach involved time-series analysis of the 1970-2000 record, developing a temporally-correlated precipitation model, and then applying the precipitation model for future predictions. The third approach involves adjusting the 1970-200 historical precipitation using outputs from global climate models. Several climate model-climate scenarios were included in this approach. The sensitivity of available reservoir storage to each of the future precipitation scenarios is assessed. The effects of various sources of uncertainty, such as uncertainty in rainfall-runoff model predictions, also are assessed.