Effects of climate change on the environmental flows in the Conchos River (Chihuahua, Mexico)

摘要

This study analyzes the water availability in the Conchos River basin (Northern México) through the amount and frequency of the precipitation. Precipitation is associated with the environmental flows in determining how much of the flow in the river has been altered by the effects of climate change or human influence. Changes in water were determined by two precipitation periods: before (1961–1983) and after (1984–2008), using a climatological mesh database created by Center of Scientific Research and Higher Education of Ensenada. Two periods for their differences in the Standardized Precipitation Index (SPI) was calculated. IHA V7 program was used for the analysis of environmental flows. In the after period, there were significant increases in precipitation during the rainy season, with a substantial decrease in minimum precipitations and in the number of storms. On the other hand, during the dry season, it rained less, making the climate extreme and indicating a change in the humidity patterns. There was a total alteration of the environmental flows of the river. This aspect generated a total loss of the frequency, magnitude, duration, and periodicity of the environmental flows during the year due to the management of the dam for electricity generation, irrigation, and flood control, altering the composition, structure and function of the riparian ecosystem. However, the synergic effect of climate on the water availability was observed. Advantage of determining environmental flows is that decision-makers can know how many changes have been introduced into the river flow patterns by human consumption or by climate change.