Observed interannual variability and projected scenarios of drought in the Chorotega region, Costa Rica
Fecha
2024
Tipo
artículo original
Autores
Ríos Solano, Melissa
Durán Quesada, Ana M.
Birkel Dostal, Christian
Hidalgo León, Hugo G.
Cabos Narvaez, William David
Sein, D. V.
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Resumen
Los análisis del desarrollo de la sequía en la región Chorotega basados en observaciones, muestran que, a pesar de que el área es relativamente pequeña, se presenta una variabilidad espacial en la sequía agrícola. Sin embargo, la ausencia de información de radiación neta dificulta la capacidad de proporcionar estima-ciones fiables de evapotranspiración (ET), afectando la evaluación de la ocurrencia de la sequía, ya que su propagación a través del sistema hidrológico es muy sensible al método de estimación de ET. La precisión de los productos satelitales del Índice de Vegetación Normalizada (NDVI, por su sigla en inglés) y la falta de información sobre riego en las áreas agrícolas limita la capacidad de establecer adecuadamente una relación entre la sequía y la respuesta de la vegetación. Con base en las observaciones, el déficit de precipitación más pronunciado ocurre entre septiembre y octubre (–100 mm en promedio), demostrando que los cambios en la circulación de gran escala son responsables de la sequía extrema en la región. Según estudios previos, El Niño-Oscilación del Sur (ENOS) modula la variabilidad de la sequía. En su fase cálida, ENSO se favorece el desarrollo de la sequía, especialmente entre agosto y octubre con correlaciones superiores a –0.6. Las proyecciones de cambio climático en los escenarios RCP4.5 y RCP8.5 sugieren una intensificación de los eventos secos en la región Chorotega a mediados de siglo, siendo la cuenca Tempisque-Bebedero la zona más afectada en términos de disminución de las precipitaciones y el calentamiento. Se proyecta un aumento de 1 ºC en la temperatura media y de hasta 2 ºC para la temperatura máxima y mínima para 2050, y una disminución de 400 a 800 mm en la precipitación anual en ambos escenarios.
The observation-based analysis of drought development in the Chorotega region showed that, despite the area being relatively small, agricultural drought exhibits high spatial variability across the region. However, the lack of net radiation data hinders the capacity to provide reliable estimates of evapotranspiration (ET), affecting the assessment of drought occurrence, since its propagation across the hydrological system is very sensitive to the ET estimation method. The coarse resolution of satellite-derived Normalized Difference Vegetation Index (NDVI) products and the lack of information on irrigation in agricultural areas limits the ability to properly establish a relationship between drought and vegetation response. Based on the observations,the most prominent precipitation deficits occur between September and October (–100 mm on average), showing that changes in the large-scale circulation are responsible for the impact of severe drought in the region. In agreement with previous studies, El Niño-Southern Oscillation (ENSO) is the main modulator of the drought severity, with the warm ENSO phase favoring an enhanced drought development and its influence being more significant between August and October, displaying correlations greater than –0.6. The climate change projections under RCP4.5 and RCP8.5 scenarios suggest the intensification of drought events in the Chorotega region at mid-century, with the Tempisque-Bebedero basin being the most affected area in terms of precipitation decrease and warming. The projected scenarios correspond to an increase of 1 oC for mean temperature and more of 2 oC for minimum and maximum temperature in the 2050 horizon, as well as a decrease of 400 to 800 mm for annual precipitation under both RCPs
The observation-based analysis of drought development in the Chorotega region showed that, despite the area being relatively small, agricultural drought exhibits high spatial variability across the region. However, the lack of net radiation data hinders the capacity to provide reliable estimates of evapotranspiration (ET), affecting the assessment of drought occurrence, since its propagation across the hydrological system is very sensitive to the ET estimation method. The coarse resolution of satellite-derived Normalized Difference Vegetation Index (NDVI) products and the lack of information on irrigation in agricultural areas limits the ability to properly establish a relationship between drought and vegetation response. Based on the observations,the most prominent precipitation deficits occur between September and October (–100 mm on average), showing that changes in the large-scale circulation are responsible for the impact of severe drought in the region. In agreement with previous studies, El Niño-Southern Oscillation (ENSO) is the main modulator of the drought severity, with the warm ENSO phase favoring an enhanced drought development and its influence being more significant between August and October, displaying correlations greater than –0.6. The climate change projections under RCP4.5 and RCP8.5 scenarios suggest the intensification of drought events in the Chorotega region at mid-century, with the Tempisque-Bebedero basin being the most affected area in terms of precipitation decrease and warming. The projected scenarios correspond to an increase of 1 oC for mean temperature and more of 2 oC for minimum and maximum temperature in the 2050 horizon, as well as a decrease of 400 to 800 mm for annual precipitation under both RCPs
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Palabras clave
drought, evapotranspiration, vegetation, projections