Evolving pathways towards water security in the Vietnamese Mekong Delta: An adaptive management perspective.

The interplay of climate change, upstream hydropower development, and local water engineering interventions for agricultural production contributes substantially to the transformation of waterscapes and water scarcity in the Vietnamese Mekong Delta. This paper aims to examine how these dynamics are linked to the paradigm shift in water management in An Giang and Ben Tre, the two ecologically distinct provinces that face serious water scarcity in the delta. We used the adaptive management concept to examine how state-led policy directions from food security towards water security enable change in water management that gives priority to water retention. While policy learning is evident, questions remain about how this ad-hoc solution could help address the presently acute water scarcity and water security over the long term. The paper advocates achieving water security should focus not only on diplomatic interventions into upstream climate-development complexities but also local water-livelihood politics.

Identifying the impact of land use land cover change on streamflow and nitrate load following modeling approach: a case study in the upstream Dong Nai River basin, Vietnam.

Tri An Reservoir is a vital source of water for agriculture, industry, hydropower, and public usage in Southern Vietnam. Due to human activities, water eutrophication has become a serious problem in recent decades. This study investigated for the first time the impact of land use and land cover (LULC) change on streamflow and nitrate load from the upstream Dong Nai River basin, which is the largest watershed of the reservoir. The study utilized several LULC scenarios, including LULC 2000, 2010, and 2020. The SWAT model was applied to model the watershed during the period 1997-2009. Results showed that the hydrological model performed satisfactorily based on the Nash-Sutcliffe efficiency (NSE) coefficient, the root mean square error observations standard deviation ratio (RSR), and the percent bias (PBIAS). The average simulated values of monthly streamflow and nitrate load were 453.7, 450.0, 446.7 m3/s and 17,699.43, 17,869.13, 17,590.81 tonnes for the LULC 2000, 2010, and 2020 scenarios, respectively. There were no significant differences in streamflow and nitrate load at the basin level under the different LULC scenarios. However, when looking at the subbasin level, there were differences in nitrate load among the scenarios. This suggests that the impacts of LULC on nitrate load may be more pronounced at smaller scales. Overall, our finding underscores the importance of modeling techniques in predicting the impacts of LULC change on streamflow and water quality, which can ultimately aid in the sustainable management of water resources.

Moving towards sustainable coastal adaptation: Analysis of hydrological drivers of saltwater intrusion in the Vietnamese Mekong Delta.

Coastal lowlands are of particular importance in providing food, shelter, and livelihoods for large populations; yet aggravating effects caused by human activities and climate change have exposed these areas to multiple challenges. Located in the southernmost part of the Lower Mekong Basin, the Vietnamese Mekong Delta (VMD) is adversely affected by upstream hydropower development, localised water-engineering systems (dykes), climatic factors, and sea level rise. This paper examines how these drivers shape the adaptation strategies of rural communities in the coastal areas. Using mixed sources of historical measured data, numerical modelling and qualitative data gathered in three coastal provinces (Ben Tre, Tra Vinh, and Soc Trang), we find that hydrological alterations are manipulated by various drivers with more immediate effects of the tidal systems and sea level rise in the Vietnamese East Sea. The study results suggest that while these impacts are not adequately addressed by delta-scale measures, a mixed policy approach including control and adaptation measures has been adopted to tackle saltwater intrusion on the local scale. The paper provides a holistic insight into the complex temporal-spatial dimensions of hydrological change which have distressed coastal agroecosystems and resource-dependent communities. The paper argues that while voicing concerns over transboundary hydropower impacts is essential, in situ collaborative efforts among salinity-affected jurisdictions are equally important in addressing high uncertainty and complexity of saltwater intrusion in the future.