The resilience and sustainability of the Mekong delta to changes in water and sediment fluxes (RAMESES)

The world's 33 largest deltas are being drowned by relative sea level rise and are, as a result, rapidly losing land. This process is also driving an exacerbation of flood risk in these environments, which is placing many large cities, key infrastructure and over 0.5 billion people at risk globally. These issues are most acute for deltas across Southern and Southeast Asia, where an estimated 20% of land will be lost by 2100. These risks are significant. For example, floods during the 2011 Asian monsoon killed an estimated 2000 people and caused ~US$45 billion in economic damage across SE Asia. Moreover, these deltas, and their ecosystem services, underpin regional food security for rapidly growing populations. There is therefore an urgent need to evolve an improved generic understanding of the processes behind the relative sea level rise and flood risk dynamics in these deltaic environments into the future.

Significant recent advances have been made in our understanding of many aspects of delta morphodynamics and evolution. This has included work on distributary channel flow processes, bifurcation stability and bar dynamics, and the profound influence of tidal backwater effects on longer-term channel hydro- and sediment dynamics. However, despite this progress there are significant uncertainties around the influence of: i) upstream migrating backwater effects, forced by sea-level rise, on delta bifurcation stability; ii) declining sediment delivery and increased hydrological variability on distributary channel stability; iii) connectivity between the channels and the delta surface on the routing, dispersal and trapping of sediment. Each of these uncertainties are key knowledge gaps that must be addressed for effective delta management, flood risk mitigation and maintenance of ecosystem services.

Our project will investigate flow and sediment routing through the Mekong delta across the annual monsoon flood and develop a new generic understanding of the impact of relative sea-level rise and sediment routing processes through distributary channels and key bifurcation sites on the delta. This will be achieved through collection of new state-of-the-art field datasets, development and application of morphodynamic numerical modelling and utilization of system dynamics modelling to guide aquaculture and agriculture adaptations to changes.

We will leverage a range of existing links we have to engage with, and communicate the outcomes of the work, to agencies and policy makers in the region and inform water resource planning and mitigation/adaptation strategies in the context of climate change.

The vulnerability of the lower Mekong to hydrological extremes has recently been highlighted in international media (BBC Mekong River Series, November 2014; The Guardian, 1st December 2015; The Economist, February 13th 2016). However, local action agencies within the region currently lack both the tools and technical capacity to evaluate the impacts of sea-level rise and extreme flood events. Our strategy is to deliver results to key stakeholders in the region who are best positioned to effectively influence decision making and policy and involves approaches across two timescales - a near-time engagement to inform in 'real-time' floods (i.e., during the course of the proposed work) and activity which will focus on legacy beyond the project. We will leverage existing links with Vietnamese government ministries and our project partners in delivery of the pathways to impact.

We will engage with key end-users in three main ways:

Policy Formulation Workshops: We will organise a set of policy workshops to enable (a) near-term adaptations to the 2017 and 2018 monsoon flood events, which are likely to be large due to transition to La Nina climate conditions; and (b) longer-term 'legacy' workshops to facilitate discussion and implication of our findings in terms of longer-term regional resilience building. We will exploit collaborations with project partners and existing links to Mekong River Commission (MRC), Viet Nam Ministry of Agriculture and Rural Development (MARD), Ministry of science and technology (MOST), Ministry of Natural Resources and Environment (MONRE) and WWF, see letters of support). In the initial workshop, we will outline the detailed and ongoing data collection and present initial outcomes from our modelling studies. We will also provide the Ministries with an updated analysis of bank erosion rates in the specific areas of interest to them. Through the use of 'sand-pit' sessions, we will use our model findings to propose potential adaptations and risk points to concentrate further modelling efforts. The legacy policy workshops will be held through 2018 and will focus not just on delivering the final results from our refined delta flood and sediment models (see CfS), but developing strategies for longer-term, 'legacy', resilience building developed in tandem with local contacts (see letters of support and track record section). These workshops will focus on the full range of impacts arising from relative sea-level rise and declining sediment loads over the mid to long term; from the impact of monsoon-season low flows on the Mekong delta. We will focus on highlighting the key areas at risk to enable relevant project partners to identify and prioritise preventative interventions. A key part of the legacy workshops will also be devoted to developing a larger funding bid (e.g., to Asia Development Bank) for funding to enable both further training and capital investment required to build lasting adaptations on the ground.

Short Courses: We will conduct at least 3 science workshops and short courses based at the University of Can Tho that will combine targeted training courses and data analysis / modelling with a set of lectures on flood risk, modelling and climate change. These will be open sessions with registration beyond the research team to the wider academic and applied communities in the region.
Project Web Site: We will create a dedicated, multi-layered, website, designed to appeal to the general public, regional stakeholders and academic scientists.
We will monitor: workshop and short course take-up; demand for public appearances/interviews for local and regional press following press releases; instances where our sensor network or modelling work has influenced 'real-time' action by stakeholders and project partners, and hit statistics for the project website and social media, including ratio of science-to-layperson hits, enquiries and follows/likes.