Public policies on water resource management and its impacts on the context of climatic changes and alterations in land use and land cover in small and protected rainforest river basins.

Climatic changes and land usage and cover (LULC) can significantly impact the availability of water resources in a region. On the other hand, water resources are intrinsically linked to economic production. Thus, managing water resources and their know-how on how they are affected by the climate and LULC are essential in regional development. The Global Climatic Model evaluated water resource management on its effects of climatic changes (2019–2099) based on four R epresentative Concentration Pathways (RCP 2.6, 4.5, 6.0, and 8.5) and the impact of changes in LULC in the Hydrographic Basin of the Cubatão River (HBCR), in Brazil. The fragilities of water resource management were observed. The scarcity of precipitation data made a direct impact on the estimated monthly average flow, as the estimated reduction was 45.4 % (RCP 2.6), 41.9 % (RCP 4.5), 43.2 % (RCP 6.0), and 41.7 % (RCP 8.5) by the end of the century. The forecast change in LULC reduces the impact on the decreased average monthly flow to 2.9 % by 2099 (RCP 2.6), 2.5 % (RCP 4.5), and 2.7 % (RCP 6.0 and 8.5). The actual evapotranspiration will be less than 2.4 % (RCP 2.6 and 6.0) and 2.3 % (RCP 4.5 and 8.5) with changes in the LULC in future scenarios. The HBCR already uses the entire status of authorized flow that will further aggravate as population growth continues. The results display faulty water resource maintenance of the basin that indeed will interfere in local economic development. • Climate change models estimate higher precipitation, but it is still insufficient. • Without the management of water resources, economic development is threatened. • The lack of instrument prevents the management of water resources. [ABSTRACT FROM AUTHOR]