Tendencia actual y futura de la precipitación en el sur de la Región Pampeana (Argentina)

• Autores: Federico Ferrelli, Andrea Soledad Brendel, María Cintia Píccolo, Gerardo M. E. Perillo
• Localización: Investigaciones geográficas, ISSN 0188-4611, ISSN-e 2448-7279, Nº. 102, 2020
• Idioma: español
• Títulos paralelos:
  • Current and future trends of precipitation in the south of Pampas (Argentina)
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• Dialnet Métricas: 4 Citas
• Resumen
  • español

    El estudio actual y futuro de la precipitación es fundamental para diseñar políticas orientadas a planificar el espacio y adquiere mayor importancia en las regiones semiáridas. El sur de la Región Pampeana es un área agrícola donde los cultivos de secano ocupan la mayor extensión. Por lo tanto, el conocimiento de sus regímenes pluviométricos anuales y estacionales junto con sus cambios espacio-temporales es de vital importancia para garantizar su sustentabilidad económica y ambiental. En este contexto, el objetivo de este estudio fue analizar la variabilidad pluviométrica en el pasado reciente, el presente, el futuro cercano y el lejano en distintos escenarios de concentración de gases de efecto invernadero. Para ello, se trabajó con datos in situ y el modelo climático CCSM4. Se analizó el período 1960-2010 para evaluar si ambas fuentes de datos son estadísticamente iguales. El patrón anual, estacional y espacial de las series de precipitación correspondientes a los períodos 1977-1997, 1998-2018, 2019-2039 y 2079-2099 fueron comparados. Los resultados demostraron que en el norte del área de estudio se incrementan los montos anuales de precipitación hasta en 200 mm anuales en el futuro lejano, mientras que en el sur se observó una disminución de @ 50 mm, pero con un aumento de la frecuencia de los años lluviosos. El análisis de las isohietas evidenció la misma tendencia, destacándose el otoño como la única estación del año en la que se observó un incremento de las precipitaciones en el sur de la zona estudiada. Los resultados servirán de base para que los actores sociales con poder de decisión tanto públicos como privados dispongan de una herramienta útil para generar un ordenamiento sustentable del territorio.

  • English

    Current and future studies on precipitation are essential for designing space-planning policies, being particularly relevant in semi-arid regions. The south of the Pampas region is an agricultural area where rainfed crops occupy the largest area. This area, located in a transition zone between temperate and semi-arid climates, is characterized by the occurrence of the most severe and lasting extreme events of the whole region. Therefore, knowledge of their current and future seasonal and annual rainfall regimes, along with their spatial-temporal changes, is essential to ensure the economic and environmental sustainability of this area. In this context, this study analyzed rainfall variability in six periods defined as recent past (1977-1997), present (1998-2018), near future (2019-2039), and distant future (2079-2099). The latter two were identified considering two greenhouse gas (GHG) concentration scenarios. We worked with on-site data from six weather stations and those from the Community Climate System Model version 4 (CCSM4) climate model.In a first instance, the period 1960-2010 was analyzed to evaluate whether both data sources were statistically equivalent. To this end, mean values and standard deviations were calculated, followed by Fisher and Kolmogorov-Smirnov tests. After demonstrating that the datasets were statistically homogeneous, the annual, seasonal, and spatial patterns of each weather station were compared for the periods previously defined. We analyzed the mean values, homogeneity, trends, and spatial behavior. The trend was evaluated using the Mann-Kendall test, and the time series were analyzed with an empirical probability study. In addition, the spatial-temporal variation was explored applying the Kriging interpolation method.The study area showed significant changes between the periods considered. These included changes in mean values. For example, the north showed four periods with different precipitation levels, while only three were observed in the south. In all cases, we found a highly significant statistical significance (Fisher's statistic < 0.001), considering an α of 5 %.For its part, the analysis of trends showed an increase of annual precipitation in the distant future in the north. At Coronel Suárez (north), for example, annual precipitation figures were 864 and 1093 mm for the present and the distant future, respectively. However, the south of the study area showed a @ 50 mm decrease, but with an increase in the frequency of rainy years. This was evident, for example, in the Hilario Ascasobi station, showing a decreasing trend with annual precipitation figures ranging from 520 mm in the past to 442 mm in the distant future (GHG concentration of 4.5).The region showed a marked seasonality in future precipitation estimates. The highest amounts occur during summer and spring, being intermediate in autumn and lowest in winter. This same pattern was observed across most of the study area, except for Hilario Ascasobi (located to the south), where summer was the season with the lowest precipitation levels in the past and present. However, the seasonal pattern in the near and distant future was similar to the pattern in the rest of the study area. Autumn was the only season when precipitation increased in the south of the study area (@ 30 mm).The importance of assessing past, present, and future changes in precipitation lies in their direct relationship with productive activities in the study area. The inter-annual and seasonal variability of precipitation given the different growth stages of rainfed crops, while exposing the population to flood and drought risks, thus affecting their access to the resource. Therefore, these results will set the grounds for public and private decision-making social stakeholders to have a useful tool for sustainable land-use management.