Ecohydrological Resistance and Resilience Analysis in a Tropical Landscape Using the Budyko Framework

Abstract:

Water resources management in tropical landscapes is challenged by the multiple and complex interactions between vegetation, soil and atmosphere and requires a systematic quantification of the changes occurring within the hydrological cycle in relation to ecological processes. In this study, we investigated hydro-climatic conditions in Costa Rica, a country located within the climate change ‘hot-spot’ of Central America. Using the Budyko’s curve and its physically-based framework, 31 stations across the Caribbean and Pacific slopes were classified according to their annual partitioning of precipitation (P) into actual evapotranspiration (AET) and potential evapotranspiration (PET) between 1989 and 2005. Based on the ecohydrological concept developed by Tomer and Schilling (2009), stations located on the Caribbean slope are characterized by low resistance and high resilience to changes in the hydro-climatic conditions, with small relative changes in the water excess (-8.5 % – 1.4 %), whereas stations located on the northern Pacific slope have high resistance and low resilience and showed marked changes in the water excess (-11 % – -82%) which are linked to climate change. Some stations located close to protected areas on both slopes showed an improvement in the hydrological conditions explained by an increment in conservation cover. A correlation analysis based on interannual AET/P anomalies vs. sea surface temperature anomalies in the Pacific and Tropical North Atlantic shows that the changes in AET/P observed in the northern Pacific region were influenced by sea surface temperature anomalies in the Pacific region El Niño 3.4 and the Tropical North Atlantic Ocean (r = 0.565, p = 0.017 and r = -0.576, p = 0.015, respectively). Our findings demonstrate that regions like the northern Pacific of Costa Rica can be considered highly susceptible to on-going climate change and manifest the need for national and regional strategies to manage effectively the available water resources across the country. They also emphasize the need to include a climate variability component in future water management plans.

Reference

Tomer, M. and Schilling, K. 2009. A simple approach to distinguish landuse and climate-change effects on watershed hydrology, J. Hydrol., 376, 24–33. doi:10.1016/j.jhydrol.2009.07.029.