Programa de Pós-Graduação em Engenharia Agrícola - PPGEA/DENA/CCA/UFC CLIMATE CHANGE IMPACTS ON WATER RESOURCES AVAILABILITY IN A SEMIARID WATERSHED IN BRAZIL AUTHORS: José Ribeiro de Araújo Neto1, Maria João Simas Guerreiro2, Pedro Henrique Augusto Medeiros3 AFFILIATIONS: 1Federal University of Ceará – UFC, 2Fernando Pessoa University – UFP, 3Federal Institute of Ceará - IFCE, Campus Maracanaú. juniorifcelabas@gmail.com Motivation Results The semi-arid region of the Brazilian Northeast is water scarce with irregular rainfall patterns. Predicted climate change scenarios may have a huge impact on the region, accentuating water scarcity and its relationship with the social and economic dynamics of the region. Climate change affects surface runoff and resulting river flow, which in turn affects water storage in the artificial reservoirs, the main water source of the region. These changes may compromise water supply for the population and crop production. Specific Goals The objective of this work was to evaluate the possible impacts of climate change on surface runoff and the availability of water resources in a watershed located in the Brazilian semi-arid region. Figure 2 – Estimated (SWAT) accumulated surface runoff between 2046 and 2064 for the proposed climate change scenarios. Methodology (a) (b) (c) Hydrosedimentological model: SWAT (Soil and Water Assessment Tool) Climate change scenarios based on the A1B report proposed by the Intergovernmental Panel on Climate Change (IPCC) NO CHANGE – Climate variables generated by WXGEN (in SWAT) based on the actual weather normals of a meteorological station located in the watershed. CCCMA/CGCM3.1 - Canadian Centre for Climate Modelling and Analysis (CCCMA), Canada. IPSL/CM4 – Institut Pierre Simon Laplace (IPSL), France. MRI/CGCM2.3.2 - Meteorological Research Institute (MRI), Japan Meteorological Agency, Japan. Figure 3 – Estimated annual surface runoff, maximum and minimum temperature between the years 2046 and 2064 for the proposed climate change scenarios. Based on the proposed climate change scenarios, it is expected a significant reduction in runoff between 2046 and 2064 when compared to the actual values (Figure 2): 4 times less water production in the CCCMA / CGCM3.1 scenario; 14 Times less water production in the IPSL / CM4 scenario; 22 times less water production in the Model MRI / CGCM2.3.2 scenario; These results may be explained by the combination of rainfall reduction (Figure 3a) and increase in maximum (Figure 3b) and minimum (Figure 3c) temperatures and consequent increase in evaporation rates in those climate change scenarios. Case Study The experimental watershed is located in the semi-arid - EIB (Figure 1), Ceará, Brazil. It has an area of ​​14.72 km2, an average elevation of 217.8 m, average rainfall 868.4 mm.year-1 and average potential evaporation 1,988.0 mm. year-1. Conclusions 1. Future scenarios of climate change show a worrying result regarding the availability of water resources in the Brazilian semi-arid region. 2. The region may be more vulnerable to serious socio-economic and environmental impacts as a result of climate change. 3. Predicted reduction in surface runoff and resulting lower availability of water resources may lead the region to a catastrophic crisis, affecting mostly the smallholder farmers. Reference: IPCC - Intergovernmental Panel on Climate Change. Available in: http://www.ipcc.ch. Accessed in: June 16, 2017. Figure 1 - Location of the Iguatu Experimental Basin - EIB, Ceará, Brazil.