Introduction Long list

This study focuses on the region surrounding the freshwater Mekong River countries. To identify NbS measures, a literature study was conducted, incorporating an Urban Ecosystem-based Adaptation to Climate Change in Vietnam (SIPA, 2022), NbS catalogue (World Bank, 2021), NbS for Building with Nature Concepts (Ecoshape, 2021), and Building Resilience in Towns and Cities: Case Studies from the Greater Mekong Subregion (ADB, 2016). We specifically focussed on finding suitable NbS for six major issues that have been identified on the Mekong River.

Major issues

  1. Changing Hydrology: The operation of dams upstream, combined with the impact of land use change and climate change, affects the river's natural flow, altering the river's hydrological patterns, leading to increased variability in flow and water levels. This disruption in the river's hydrological regime can have severe consequences for agriculture, fisheries, and the overall ecosystem in the Mekong River Region.

  2. Erosion and Sedimentation: Rivers are vital in carrying sediment downstream and are crucial for building and maintaining dynamic and fertile floodplains. In addition, sediments are crucial to the morphological stability of the channels, levees, and coasts that support many socio-economic activities. However, the construction of large dams with reservoirs upstream has disrupted this natural process. These dams have significantly reduced sediment supply, resulting in increased erosion in certain areas and excessive sediment deposition in others.

  3. Biodiversity Loss: Biodiversity loss in rivers, lakes, and wetlands is occurring at an alarming rate, and it has become a global concern. Dudgeon and his colleagues (2006) identified five primary causes of freshwater biodiversity decline: flow alteration, pollution, habitat degradation and loss, overexploitation of species, and the introduction of invasive non-native species. In the context of the Mekong River, the presence of dams, with their distinct and conservation-focused purposes, leads to the fragmentation of freshwater ecosystems and disrupts the movement of water, species, sediments, and nutrients, all vital for sustaining biodiversity.

  4. Food Security: The Mekong River and its delta are essential for food production in the region, providing a significant portion of the country's rice and fish supply. Climate change-related impacts on agriculture and fisheries can threaten food security for millions of people.

  5. Increased water demand: During the dry season, the runoff of the Mekong River basin needs to increase by about 3000 m3/s if it is to meet the water demand of all the riparian countries (Tang, 1999). Consequently, the water deficit in the dry season is nearly 47.30 km3. The available water during the dry season is 82.26 km3 (State of the Basin Report, 2017, Tang, 1999).