Integrated assessment of storm surge barrier systems under present and future climates and comparison to alternatives: a case study of Boston, USA

Large-scale barriers are a management option for present and increasing coastal storm flooding. The barriers have gates that are open most times except during storms. As an example of the assessment process for a barrier, an integrated assessment of two barrier options for the coastal city of Boston, located in the northeastern USA, is presented. The assessment also included a comparison to shore-based adaptation options such as elevated walkways, playing fields, and open space. While harbor-wide barriers in Boston could manage storm coastal flooding with perhaps minimal environmental impacts and moderate impacts on harbor users such as shipping, their cost-effectiveness is low. Their operational lives are limited by a rapidly increasing annual number of gate closures over time as sea level rises—placing considerable mechanical stresses on them. With low potential to adapt or adjust a barrier once it is in place, there are limited opportunities to respond to the uncertainties of climate change over time. The alternative of a wide spectrum of shore-based, district-level solutions using nature-based solutions located on the waterfront, however, has the potential for high cost-effectiveness and several key advantages. These solutions have the potential to incorporate multiple levels of protection, manage storm and tidal coastal flooding, provide flexibility and adaptability, offer co-benefits, endure for long operational lifetimes, and cause minimal impacts to the environment and harbor users.