Resumo

ARELLANO MONTERROSAS, José Luis L.  e  RUIZ MEZA, Laura Elena. Evaluation and trends of the hydrological ecosystem services of the Zanatenco river basin, Chiapas. Invest. Geog [online]. 2018, n.95. ISSN 2448-7279.  https://doi.org/10.14350/rig.59467.

This study analyzes interannual trends in Hydrological Ecosystem Services (HES) in the Zanatenco river basin, located in the Hydrological Region 023 Coast of Chiapas, for the period 1961-2013. We have evaluated the regulating HES related to water flows, control of hydric erosion, as well as the provisioning HES related to water.

We analyzed the interannual variability in hydrological balance (precipitation-evaporation) and runoff index (runoff/precipitation). For the evaluation of regulating HES related to erosion control, land-use and vegetation dynamics in the basin were analyzed for the years 1985, 1993, 2002, 2007, and 2011, as well as their effect on erosion. Finally, the provisioning HES were assessed through the relationship between water supply and demand, considering both surface water and groundwater, for the various water uses in the basin.

Decreasing trends were observed in the interannual variability of precipitation, runoff and the runoff index. These trends reveal a higher deficit of moisture in soil, which defines the marked seasonal regime of the Zanatenco river. Extreme Potential Hydric Erosion (PHE) occurs in rough terrain, which covers 72% of the basin; on the other hand, extreme Actual Hydric Erosion (AHE) over the five years of study represents on average 30% of the area of the basin. The areas with vegetation cover, particularly within La Sepultura Biosphere Reserve, provide a protective HES for the control of hydric erosion in the basin. The interannual variability of surface runoff is decreasing at an annual rate of 2,365 million m3. In this way, the significant decrease in runoff, the extreme dry season, and its decreasing interannual trend, altogether result in drought periods that are becoming more frequent and intense in the basin. This hydric imbalance is evident in the water supply deficit currently affecting the inhabitants of the city of Tonalá, Chiapas.

Palavras-chave : hydrological ecosystem services; hydrological balance; runoff index; hydric erosion; water supply and demand; coast of Chiapas.