Distributed hydrologic modeling in northwest mexico reveals the links between runoff mechanisms and evapotranspiration

Document Type

Article

Publication Date

8-8-2012

Abstract

Adistributed hydrologicmodel is used to evaluate howrunoffmechanisms-including infiltration excess (R I), saturation excess (R S), and groundwater exfiltration (R G)-influence the generation of streamflow and evapotranspiration (ET) in amountainous region under the influence of theNorthAmericanmonsoon (NAM). The study site, the upper SonoraRiver basin (~9350 km 2) inMexico, is characterized by a wide range of terrain, soil, and ecosystem conditions obtained from best available data sources. Three meteorological scenarios are compared to explore the impact of spatial and temporal variations of meteorological characteristics on land surface processes and to identify the value of North American Land Data Assimilation System (NLDAS) forcing products in the NAM region. The following scenarios are considered for a 1-yr period: 1) a sparse network of ground-based stations, 2) raw forcing products from NLDAS, and 3) NLDAS products adjusted using available station data. These scenarios are discussed in light of spatial distributions of precipitation, streamflow, and runoffmechanisms during annual, seasonal, and monthly periods. This study identified that the mode of runoff generation impacts seasonal relations between ET and soilmoisture in the water-limited region. In addition, ET rates at annual and seasonal scales were related to the runoff mechanism proportions, with an increase in ET when R S was dominant and a decrease in ET when R I was more important. The partitioning of runoffmechanisms also helps explain themonthly progression of runoff ratios in these seasonallywet hydrologic systems. Understanding the complex interplay between seasonal responses of runoff mechanisms and evapotranspiration can yield information that is of interest to hydrologists and water managers. © 2012 American Meteorological Society.

Publication Title

Journal of Hydrometeorology

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