• Energy Research

AbstractUrban wetlands are one of the important natural resources in cities and have an essential role in the sustainability of the urban environment. They offer various ecosystem services in cities, for example, by mitigating the risk of floods, providing water purification, groundwater regulation, and biodiversity promotion. Urban wetlands also provide recreational opportunities such as swimming and boating, that improve citizens’ well-being. Unfortunately, human activities and environmental factors have been the primary reasons that have destroyed urban wetlands. To identify the main factors which threaten wetlands, as a case study, we investigated the environmental history of six urban wetlands in Helsinki starting from 19th century to the present. We collected historical information from available documents such as research articles, technical reports, maps, and photos, and then we compared the past situation of these urban wetlands with the current conditions throughout history. We also support our statements by referring to urban wetlands with similar conditions from different continents to explain the reasons for wetlands’ disappearance, degradation, or survival. We show that population growth, land-use change, and climate change have been the main threats that have caused the degradation and even the loss of urban wetlands. We discuss the influencing factors which threaten urban wetlands and we highlight the role of policy and decision-makers in the rehabilitation and maintenance of urban wetlands.

Wetlands are a critical part of natural environments that offer a wide range of ecosystem services. In urban areas, wetlands contribute to the livability of cities through improving the water quality, carbon sequestration, providing habitats for wildlife species, reducing the effects of urban heat islands, and creating recreation opportunities. However, maintaining wetlands in urban areas faces many challenges, such as the reduction of hydrological functions, changed water regimes due to barriers, contamination by wastewater, habitat loss due to land-use change, and loss of biodiversity due to the entry of alien species. In this article, we review the theoretical background of wetlands in urban areas through the existing studies in the literature. We provide knowledge on urban wetlands and highlight the benefits of these wetlands in urban areas. These benefits include sustainability, biodiversity, urban heat islands, social perception, and recreation values. We also summarize the objectives, methodologies, and findings of the reviewed articles in five tables. In addition, we summarize the critical research gaps addressed in the reviewed articles. Our review study addresses the research gaps by performing a rigorous analysis to identify significant open research challenges, showing the path toward future research in the field. We further discuss and highlight the role of policymakers and stakeholders in preserving wetlands and finally present our conclusions.