Ecosystem Service Modelling to Support Nature-Based Flood Water Management in the Vietnamese Mekong River Delta

Abstract

Deltas are among the most productive and diverse global ecosystems. However, these regions are highly vulnerable to natural disasters and climate change. Nature-based solutions (Nbs) have been increasingly adopted in many deltas to improve their resilience. Among decision support tools, assessment of ecosystem services (ES) through spatially explicit modelling plays an important role in advocating for Nbs. This study explores the use of the Land Utilisation and Capability Indicator (LUCI) model, a high-resolution model originally developed in temperate hill country regions, to map changes in multiple ecosystem services (ES), along with their synergies and trade-offs, between 2010 and 2018 in the Vietnamese Mekong Delta (VMD). In so doing, this study contributes to the current knowledge in at least two aspects: high-resolution ES modelling in the VMD, and the combination of ES biophysical and economic values within the VMD to support Nbs implementation. To date, this is the highest resolution (5 by 5 m) ES modelling study ever conducted in the VMD, with ~1500 million elements generated per ES. In the process of trialling implementations of LUCI within the VMD’s unique environmental conditions and data contexts, we identify and suggest potential model enhancements to make the LUCI model more applicable to the VMD as well as other tropical deltaic regions. LUCI generated informative results in much of the VMD for the selected ES (flood mitigation, agriculture/aquaculture productivity, and climate regulation), but challenges arose around its application to a new agro-hydrological regime. To address these challenges, parameterising LUCI and reconceptualising some of the model’s mechanisms to specifically account for the productivity and flood mitigation capability of water-tolerant crops as well as flooding processes of deltaic regions will improve future ES modelling in tropical deltaic areas. The ES maps showed the spatial heterogeneity of ES across the VMD. Next, to at least somewhat account for the economic drivers which need to be considered alongside biophysical valuations for practical implementations of ES maps for nature-based solutions (Nbs) in the upstream VMD, economic values were assigned to different parcels using a benefit transfer approach. The spatially explicit ES economic value maps can inform the design of financing incentives for Nbs. The results and related work can be used to support the establishment of Nbs that ultimately contribute to the security of local farmers’ livelihoods and the sustainability of the VMD.

An ecological economic comparison between integrated rice-fish farming and rice monocultures with low and high dikes in the Mekong Delta, Vietnam

“…The Mekong Delta has been of critical importance for rice production for decades and will most likely continue to be so (Dang et al 2021 ; Lan and Nguyen. 2021 ).…”

“…The majority of the farmers also felt that high dikes had decreased the amounts of aquatic organisms, especially fish and that this had decreased the biodiversity because a loss of connectivity and habitats (cf. Dang et al 2021 ). Nguyen et al ( 2018 ) found significant decreases in the numbers of native fish and vegetables in areas enclosed by high dykes in An Giang.…”

“…Increased number of high dikes have decreased the aquatic connectivity within the Delta, followed by a decreased inflow of nutrient-rich water and sediments to agriculture areas and disrupted migration routes for fish (Tran et al 2018 , 2019 ; Nguyen et al 2019 ; Dang et al 2021 ). Increased reliance on agrochemicals and reduced exchange of water have also reduced the water quality in large parts of the Delta (Sebesvari et al 2012 ).…”

Parameterising and Adapting Ecosystem Service Models in Data Sparse Regions: Gaps, Guidelines, and an Application in the Vietnamese Mekong Delta

“…Limited detail in soil physical, chemicals and hydraulic data is common in tropical countries . Some results from the case study, e.g., drainable water, plant available water, saturated hydraulic conductivity, were used for the application of the LUCI to map multiple ecosystem services in the VMD (Dang et al, 2021b).…”

“…As articulated in the first paragraph of section 4.3 and also in Dang et al (2021b) "This is not recommended for final application of LUCI but can be a useful way of exploring model capacities and preliminary results for your region. Careful consideration should be given to whether the supported datasets span similar land use or soil types to those present in your region.…”