Integrated management of water resources and coastal zone: the zone of coastal influence in the basins of Mampituba, Ararangua, Tubarao and Tijucas rivers, SC, Brazil

The land use in the basin directly affects the coastal zone as both are connected and must be managed in an integrated manner. However, in Brazil the management policies of both environments are fragmented and there is no effective consideration that the coastal zone is part of the basin. This study aims to test whether the use of a zone of coastal influence (ZCI) based on physical criteria is useful for integrated coastal management. The physical criterion used is the propagation of tidal wave in the estuary, which is simulated by the non-permanent flow module of HEC-RAS model. The case study is the basins of Mampituba, Ararangua,Tubarao and Tijucas rivers, Santa Catarina state, Brazil. The ZCI was set using the minimum affluent flow, which leads to: up to 29 km upstream in the Mampituba River, 34.4 km in Itoupava River and 28.8 km in Mae Luzia River (both Ararangua River affluents), 20.7 km in Tubarao River and 21,25 km in Tijucas river. The model showed good results for the penetration of the astronomical tide, although the ZCI was small due to low tidal range in the analyzed estuaries. The ZCI based on physical criteria proves to be a useful tool, but the criteria used need adaptations, such as the inclusion of 50 km line from the coast or the propagation of meteorological tide. The ZCI is important to include the cause and effect relationships between land and water use and coastal zone management, especially for the grant of water rights and environmental licensing.