Coastal Development and Human Impacts Along the Rio Grande do Sul Beaches, Brazil

Rio Grande do Sul (RS), the southernmost state in Brazil, has a 630-km long shoreline dominated by undeveloped sandy beaches. Unlike other states in Brazil, its colonization was more intense inland resulting in less than 5% of the state's population living in coastal cities. Many of the urbanized shores consist in small villages occupied only in the summer months. However, in the last decade there has been a change in this trend as coastal population is growing faster than the state's average. Many studies show that most of RS beaches are retreating, so it is urgent the implementation of a management plan to regulate occupation along the undeveloped shores to avoid new settlements in a hazardous coast. This work characterizes the RS coast based on the state of alteration of its beaches, which might be useful to support a statewide coastal management plan. The state shores were classified into four classes according to the dominant coastal environment (rocky headlands or open sandy beaches), type and distribution of developed shores (i. e. degree of urban development, type of beachfront constructions, urbanization in dune areas), and the impact of human activities. Developed and impacted shores comprise Classes 1,2, and 3 that are prograding beaches influenced by headlands, accreted open sandy beaches, and mainly retreating open sandy beaches, respectively. Class 4 consists in undeveloped sandy beaches that represents 76% of the state shoreline length. Despite the long undeveloped shore segments, human activities are already impacting 31% of the RS shoreline. The length of impacted shores might increase in the near future (due to the implementation of new road access to undeveloped areas) as unplanned new development occurs along retreating shores.