By Emilie Cremin (School of Interdisciplinary Studies) and Fabrice Renaud (School of Interdisciplinary Studies)

Nowadays, river deltas are spaces of high vulnerability due to the conjunction of hydro-meteorological and geophysical hazards, fragile ecosystems, social and economic demands, and the effects of human actions on the environment. Between land, large river systems and the sea, river delta waterscapes are generally densely populated places, where communities have developed their livelihoods based on the cultivation of rice, orchards, aquaculture, and capture fishery.

Delta communities also interact with habitats including mangroves and wetlands that provide ecosystem services such as honey, firewood, and aquatic organisms. However, upstream dam construction, channelisation and underground extraction of natural resources, in particular freshwater, in the deltas themselves affect water and sediment flows and lead to land subsidence.  Communities, and their livelihoods, are also impacted by coincident hazards including river and coastal floods, droughts, cyclonic activities and salinity intrusion.  

Our research team at Glasgow’s School of Interdisciplinary Studies focuses on environmental risk reduction strategies in three Asian deltas: the Ganges-Brahmaputra-Meghna delta in India and Bangladesh, as well as the Mekong and the Red River deltas in Vietnam. This research is a part of the UKRI GCRF Living Deltas Hub.  

The tools and the risk assessment we are developing are based on the existing Global Delta Risk Index (Sebesvari et al. 2016; Hagenlocher et al. 2018), which is designed to consider the links between social and ecological systems as a key to understanding the causes of the ecological threats in deltas. With our new approach, we are analysing different components of environmental risk (anthropogenic drivers, exposure, hazard, vulnerability, and coping and adaptation capacities) to support decision making, and ultimately, the selection of optimal solutions for sustainable development of the deltas’ most vulnerable landscapes. 

Defining Environmental Risks with Communities  

To assess environmental risks, we work with delta communities and stakeholders through focus group discussions and participatory mapping activities in the field. Together, we identify natural hazards, ecological vulnerability, social vulnerability and the relative exposure of coastal socio-ecological systems linked to mangroves, to wetlands more broadly, or to agricultural activities such as rice cultivation or aquaculture. 

Boats are waiting to be repaired to transport goods and people across a large channel of the Bengal delta. A woman is collecting some dry wood and leaves from the mangrove to make fire for cooking. @Emilie Cremin, March 2020 

In order to understand the complexity of the overall system, in parallel, we are organising online workshops with multidisciplinary scientists, delta experts and delta stakeholders to design  ‘cause-effect chains’ (Fig. 1), an analytical tool that helps to understand, systemise and prioritise the factors that drive risk (GIZ, EURAC & UNU-EHS, 2018). Secondary data, and primary data collected through surveys will be processed and visualised in GIS mapping, to prioritise risk factors.

Fig 1. Draft Ganges-Brahmaputrawatershed diagram and related summary of an impact chain Source: Adapted from Emilie Cremin, 2014.

Our surveys have already informed us about the impact of human actions on delta socio-ecological systems: the construction of dams in the river basins captures sediments and stores freshwater upstream decreasing sediment load; the embankments along the riverbed reduce sediment deposits within the flood plain creating river dysconnectivity, which leads to erosion and contributes to the subsidence of the deltas. Moreover, delta experts have also observed that soil salinisation has reduced rice crop productivity. This process is related to freshwater retention by dams during the dry season but could be also exacerbated by sea level rise, as reported by the IPCC (2012). Global warming is the main driver of sea level rise, which leads to increased coastal inundation and salinity intrusion (IPCC, 2012). These processes have important impacts on communities’ livelihoods where they are dependent on agriculture. Therefore, some communities are, for example, changing their livelihoods from agriculture to aquaculture. This change in land use might be irreversible as soils are becoming saline. The transformation usually also negatively affects habitats such as mangroves.  

Erosion along a channel leading to a polder in Satkhira district (Bangladesh). The communities are trying to rebuild the embankment during the low tide and the dry season. @Iain Garett, March 2020 

Co-produced solutions for the sustainable development of river deltas 

The GDRI is designed as a tool for policy makers to inform actions. It aims to understand complex social-ecological systems and how they transform with time. There are many approaches available to reduce environmental risks such as improved early warning systems, engineered structures, and nature-based solutions, which draw on ecosystems’ abilities to provide regulating and provisioning ecosystem services (Cohen-Shacham et al. 2016). Many nature-based solutions have already been proposed to mitigate the effects of catastrophic events, such as restoring mangroves along the coast to retain sediments, mitigate coastal erosion, and dampen wave action. We are also looking at co-produced knowledge and solutions resulting from communities’ local ecological knowledge, engineers’ technical perspectives and ecosystems monitoring, for the sustainable development of delta socio-ecological systems.  

Our research project is a part of the UKRI GCRF Living Deltas Hub, funded by UKRI via their Global Challenges Research Fund. The Interdisciplinary Research Hub, one of only 12 awarded, is working across four delta social-ecological systems in Vietnam (Red River and Mekong River deltas) West Bengal and Bangladesh (Ganges Brahmaputra Meghna delta) to achieve UK-ODA objectives of sustainable development for the direct socio-economic benefit of these Low and Medium Income Countries (LMIC). The Living Deltas Hub is an international project that aims to safeguard delta futures in South and SE Asia through more sustainable development and support delta community resilience, coping and adaptation strategies to the existential threats they face. The Hub aims to define risk, vulnerability and tipping points and feed baseline information into sustainable policy. The aspect which makes the Hub unique from previous large delta research consortia is its strong emphasis on delta natural-cultural heritage and how co-created knowledge around this can feed the voices of delta dwellers into the policy-making arena.

References:

  • Cohen-Shacham, E., Walters, G., Janzen, C. & Maginnis, S. (eds.) (2016). Nature-based Solutions to address global societal challenges. Gland, Switzerland: IUCN. xiii + 97pp. https://portals.iucn.org/library/node/46191 
  • Cremin, Emilie. 2014.  Entre mobilité et sédentarité : les Mising, "peuple du fleuve", face à l'endiguement du Brahmapoutre (Assam, Inde du Nord-Est). PhD thesis, University Paris 8 Saint-Denis, Center for Himalayan studies. https://www.theses.fr/2014PA080018 
  • Hagenlocher, M., Renaud, F.G., Haas, S. and Sebesvari, Z., 2018. Vulnerability and risk of deltaic social-ecological systems exposed to multiple hazards. Science of the total environment, 631, pp.71-80. http://eprints.gla.ac.uk/159007/ 
  • GIZ, EURAC & UNU-EHS (2018): Climate Risk Assessment for Ecosystem-based Adaptation – A guidebook for planners and practitioners. Bonn: GIZ. https://www.adaptationcommunity.net/wp-content/uploads/2018/06/giz-eurac-unu-2018-en-guidebook-climate-risk-asessment-eba.pdf  
  • Sebesvari Z., F.G. Renaud, S. Haas, Z. Tessler, M. Hagenlocher, J. Kloos, S. Szabo, A. Tejedor, C. Kuenzer, A review of vulnerability indicators for deltaic social–e- cological systems, Sustain. Sci. 11 (4) (2016) 575–590 https://link.springer.com/article/10.1007/s11625-016-0366-4   
  • Seneviratne, S.I., N. Nicholls, D. Easterling, C.M. Goodess, S. Kanae, J. Kossin, Y. Luo, J. Marengo, K. McInnes, M. Rahimi, M. Reichstein, A. Sorteberg, C. Vera, and X. Zhang, 2012: Changes in climate extremes and their impacts on the natural physical environment. In: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation [Field, C.B., V. Barros, T.F. Stocker, D. Qin, D.J. Dokken, K.L. Ebi, M.D. Mastrandrea, K.J. Mach, G.-K. Plattner, S.K. Allen, M. Tignor, and P.M. Midgley (eds.)]. A Special Report of Working Groups I and II of the Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press, Cambridge, UK, and New York, NY, USA, pp. 109-230. https://www.ipcc.ch/report/managing-the-risks-of-extreme-events-and-disasters-to-advance-climate-change-adaptation/ 

First published: 10 February 2022

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