A scoping review of coastal vulnerability, subsidence and sea level rise in Ghana: Assessments, knowledge gaps and management implications

Coastal areas are home to a myriad of essential services. However, population growth and climate change along with their cascading impacts have had profound impacts on their topography and evolution. Consequently, many coastal regions, of which Ghana's coast is no exception, are incessantly plagued with hazards that are increasing in magnitude and frequency. Predominantly through the recurrence of floods and erosion, Ghana's coast is becoming increasingly susceptible to huge socio-economic implications considering its environment-dependent economy. Therefore, attempts have been made to assess Ghana's coastal vulnerability to comprehend the complexities underpinning the occurrence of these hazards. However, most studies attribute the recurrence of floods and erosion to global sea-level rise, but coastal land subsidence could also have significant impacts. Indeed, land subsidence is a major component of relative sea-level rise (rSLR) in many coastal cities worldwide. Drawing on extant literature, this scoping study provides an overview and evaluation of three thematic areas—SLR, subsidence and coastal vulnerability—within the Ghanaian context along with their existing relationships. Additionally, it seeks to also assess available knowledge and data and to identify crucial knowledge gaps which impede comprehensive risk assessment of Ghana's coast. The survey findings, however, indicate a significant understudy of the selected thematic areas albeit posing potential threats to Ghana's coast. It brought to light the absence of a ground-validated subsidence study; a non-identification of potential local subsidence drivers; a non-availability of a subsidence-infused coastal vulnerability assessment; non-existing studies on the combined effects of climate change and subsidence; and huge deficits in available data for numerical modelling of coastal subsidence. Guided by the identified knowledge and data gaps and the need to mitigate impacts, the study recommends a thorough assessment of rSLR and vulnerability; a continuous and long-term monitoring framework for rSLR and its drivers; a hybrid approach and review of coastal management strategies; and the reinforcement of conservational laws and conventions to avert the increasing vulnerability of Ghana's coast.