Would rainfed agriculture be the right option under climate change scenarios? A case study from centro region of Portugal

Abstract

Agriculture has changed significantly during the last 30 years in Portugal.One of the main changes is related to agricultural abandonment, mainly driven by demographic dynamics on areas that are marginal in terms of productivity.Such trend affects mainly rainfed agriculture, and was significant in the inland Norte and Centro regions of Portugal between 1990 and 2010.By contrast, irrigated areas dedicated to agriculture are increasing.Considering a predicted reduction on water availability under future climatic scenarios, determined by the decrease in the amount of annual precipitation, it is necessary to set strategies to adapt agriculture to a new climatic context, considering both production and consumption/dietary trends.To do so, and using as case study the Centro Region of Portugal, this work aims to evaluate how the suitable area for agriculture might change under future climatic scenarios (RCP 4.5 and 8.5 scenarios for the two time-windows of 2041–2070 and 2071–2100), and identify measures that contribute to adapt agriculture to a new context.Such assessment is based on a modelling approach that aims to evaluate suitability to agriculture, which is set from soil properties (soil type and texture), topographic parameters (such as slope and land morphology), and climatic conditions (water deficit).The expected reduction on water availability under future climatic scenarios, combined with recent trends on agriculture, namely the reduction of rainfed agriculture and the increase of irrigated agriculture areas, points to an unsustainable situation.This is of great concern, once there is a match between areas where water deficit is predicted to increase more and areas where irrigated area is expanding today.Thus, specific adaptation strategies/policies are needed to revert/cope with such trends, which must be spatially explicit and locally meaningful.The implementation of such approaches might be oriented by results from assessment of predicted changes in terms of suitable area for agriculture, but also consider economic and dietary aspects, an exercise that we try to validate based on the conditions of the Centro Region of Portugal.