As mudanças climáticas e os desafios da gestão de águas subterrâneas no Estado do Ceará

Abstract

Climate change has been causing significant alterations in precipitation patterns, temperature, and evapotranspiration, directly affecting the hydrological cycle and, consequently, the availability of groundwater. In the State of Ceará, located in the Brazilian semi-arid region, these impacts become even more relevant given the strong dependence on aquifers for human supply, agriculture, and other economic activities. The intensification of extreme events, such as prolonged droughts, combined with the unregulated use of water resources, poses complex challenges for the sustainable management of groundwater in the region. This study analyzes the main conflicts and challenges related to groundwater management in Ceará, based on the application of the DPSIR Matrix (Driving Force – Pressure – State – Impact – Response) across the twelve hydrographic regions of the state. The analysis highlights significant conflicts, such as the unregulated drilling of wells, limitations in the control and management of groundwater permits, pollution and contamination by waste (nitrates, inorganic fertilizers, and pesticides), as well as the fragility of institutional governance.As a result, a general DPSIR matrix was developed, encompassing the characteristics and issues of the entire territory of Ceará. In addition, seven specific matrices were created, focused on the main hydrogeological domains of the different hydrographic regions, allowing for a more detailed and contextualized analysis of local dynamics.In this context, the research also seeks to estimate the effects of climate change on water availability in the Dunas/Paleodunas aquifer system in the Metropolitan Region of Fortaleza, with a particular focus on the municipalities of Paracuru and São Gonçalo do Amarante. Based on historical climatological data on precipitation and temperature, and through the application of the Climatic Water Balance method, effective infiltration was estimated for the period from 1977 to 2024. For the municipality of Paracuru, a value of 344.60 mm/year was obtained, while for São Gonçalo do Amarante the estimated value was 183.50 mm/year.Additionally, using the Water Table Fluctuation method (Δh), a renewable reserve of approximately 39 million m³ was estimated for an area of 78.55 km², corresponding to the outcropping zone of the aquifer.Based on projections from CMIP6 climate models applied to the study area, considering the SSP2-4.5 and SSP5-8.5 scenarios, future climatological data were obtained and effective infiltration values were estimated from 19 models, covering three time intervals (2025–2050, 2051–2075, and 2076–2100). For the period from 2025 to 2050, under the most critical scenario, the results indicate a 6% increase in average temperature and a 55% reduction in average effective infiltration. In the following interval (2051–2075), under the same scenario, there is an 11% increase in average temperature and an 86% reduction in effective infiltration. For the period from 2076 to 2100, the models indicate an average reduction of 98% in the worst-case scenario (SSP5-8.5) in the effective recharge of the aquifer system, highlighting potentially severe impacts on its renewal capacity.