Gestão de Água Subterrânea através do Planejamento em Escala de Paisagem: incorporação das mudanças de uso do solo e provimento de informações

Abstract

Groundwater has a fundamental role in the health of ecosystems and is the primary supply source of approximately two billion people. The pressuring demand for groundwater led to the depletion of the water levels throughout the world. Moreover, groundwater management has proven to be a challenging endeavour. Most of the traditional approaches have failed to sustain a long-term balance. Hence, integrated approaches that include the social, economic, cultural, and institutional settings of each system have been advocated; besides, information for groundwater management has always been a challenge to analyse outside the hydrogeological sphere. Groundwater and land use are intrinsically connected. Land use can influence the recharge and the water demands of the aquifer, and changes in the aquifer can impact the land use. Furthermore, land-use changes act as a mirror of socio-economic development and ecosystem change. Therefore, groundwater management needs to be linked to land use. Landscape Scale Planning is an approach for land use planning defined as an integrative framework based on evidence and centred on landscapes. This approach offers the opportunity for integration of cross-sectoral planning and management. Part of this lies in the adoption of integrative units defined as landscape units. These units are the basis for data gathering, analysis and interpretation. The objective of this thesis is to analyse the incorporation of the land-use changes into groundwater management by the application of the Landscape Scale Planning framework in a cultural landscape at the coast of Northeast of Brazil. To this end, it was investigated: how the Landscape Scale Planning and its connection with land-use changes have the potential to provide information to groundwater management; to what extent landscape units can be integrated to provide a whole-of-landscape analysis using a numerical groundwater model; and the incorporation of temporal dynamics into the analysis of groundwater management. This research has found an intrinsic connection between Landscape Scale Planning and groundwater management. Hence, the challenge lies in the frame of analysis of groundwater management from the Landscape Scale Planning perspective. Underpinned by these findings, guidelines for groundwater management based on this framework were suggested. Also, landscape units were defined and delimited using the following criteria: topographical/hydrological, hydrogeological, water demand, land use and census sector. The landscape units were applied to analyse the groundwater budget. As results, it was possible to determine the groundwater recharge distribution in the system and among the landscape units, as well as to identify the influence of the land use in the recharge of two adjacent landscape units. The application of landscape units also provided a whole-of-landscape integrated analysis of the spatial dynamics of the system that led to the identification of inter-basin groundwater flow (IGF) between two river basins in the study area. A possible reason for this IGF is the different land uses and consequent characteristic water demand. Finally, a framework for the determination of the importance of the transience to groundwater management using the basin time constant was applied. Three landscape units presented a time constant of less than 30 years, indicating the changes, such as in land use, can have more than 60% of its disturbances adjusted within a management timeframe; a possible consequence would be alteration in the groundwater availability for allocation.