Fig 4 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Monthly average discharges of the model runs under emission scenarios (2032– 2042) compared to the baseline (1982–1992). (A) Chiang Saen under A1b emission scenario; (B) Chiang Saen under B1 emission scenario; (C) Kratie under A1b emission scenario; and Kratie under B1 emission scenario.
Source publication
The transboundary Mekong River is facing two on-going changes that are estimated to significantly impact its hydrology and the characteristics of its exceptional flood pulse. The rapid economic development of the riparian countries has led to massive plans for hydropower construction, and the projected climate change is expected to alter the monsoo...
Contexts in source publication
Context 1
... the model runs using the A1b emission scenario, the wet season discharges at Kratie have more variation between the different runs than the dry season discharges (except for December) ( Fig. 4; Table 6). For the wet season, computed monthly dis- charges show a consistent increase for two runs (ccA, ncA), a varying decrease or 15 increase for two runs (giA, mpA), and a consistent decrease for one run (cnA). The increase of discharges is most pronounced at the end of the wet season/beginning of the dry season in September, ...
Context 2
... Saen, there is somewhat more variation between the different runs compared to Kratie (Fig. 4; Table ...
Context 3
... the runs using the B1 emission scenario, the increase at Kratie in September- October compared to baseline is smaller than in the runs using the A1b scenario ( Fig. 4; Table 6). There is also a decrease in monthly average discharge during June and July, 25 which is not present in the runs using the A1b scenario. The range of annual discharge change for the runs using the B1 scenario is from −6.9 % to +8.1 % ( most of the runs using the B1 scenario, staying at the baseline level only during May and ...
Context 4
... 4; Table 6). There is also a decrease in monthly average discharge during June and July, 25 which is not present in the runs using the A1b scenario. The range of annual discharge change for the runs using the B1 scenario is from −6.9 % to +8.1 % ( most of the runs using the B1 scenario, staying at the baseline level only during May and June ( Fig. 4; Table 6). The largest decrease takes place in ...
Context 5
... results indicate similar changes in Upper Mekong basin (UMB) hydrology com- pared to other existing studies (Adamson, 2001;Hoanh et al., 2010; R ¨ asänenas¨asänen et al., 2012). However, the magnitudes of the changes do vary rather significantly between the studies (Fig. S4a in the Supplement). On a seasonal scale, our findings agree well with three other studies (Fig. S4b in the Supplement). The differences in the ...
Context 6
... similar changes in Upper Mekong basin (UMB) hydrology com- pared to other existing studies (Adamson, 2001;Hoanh et al., 2010; R ¨ asänenas¨asänen et al., 2012). However, the magnitudes of the changes do vary rather significantly between the studies (Fig. S4a in the Supplement). On a seasonal scale, our findings agree well with three other studies (Fig. S4b in the Supplement). The differences in the ...
Context 7
... Kratie, our findings for the directions of flow changes are also in line with those of other basin-wide studies (ADB, 2004;Hoanh et al., 2010). The magnitude of change between the studies differs, however, more than in the UMB case (see Figs. S4 and S5 in the Supplement). Our results are well in line with the results of ADB (2004) Printer-friendly ...
Similar publications
This study assessed the regional climate models (RCMs) employed in the Coordinated Regional climate Downscaling Experiment (CORDEX) South Asia framework to investigate the qualitative aspects of future change in seasonal mean near surface air temperature and precipitation over the Hindu Kush Himalayan (HKH) region. These RCMs downscaled a subset of...
Meso- and fine-scale sea surface temperature (SST) is an essential parameter in oceanographic research. Remote sensing is an efficient way to acquire global SST. However, single infrared-based and microwave-based satellite-derived SST cannot obtain complete coverage and high-resolution SST simultaneously. Deep learning super-resolution (SR) techniq...
We introduce a continuous (downscaling) data assimilation algorithm for the 2D B\'enard convection problem using vorticity or local circulation measurements only. In this algorithm, a nudging term is added to the vorticity equation to constrain the model. Our numerical results indicate that the approximate solution of the algorithm is converging to...
This paper systematically reviews the potential of the Sentinel-2 (A and B) in assessing drought. Research findings, including the IPCC reports, highlighted the increasing trend in drought over the decades and the need for a better understanding and assessment of this phenomenon. Continuous monitoring of the Earth’s surface is an efficient method f...
This report summarized the research findings on three selected
downscaled GCMs comparison with observed data. The hydrological indexes were
calculated and correlated with past water disaster (flood/drought/landslide) records.
Future water disaster event can be projected from the GCM data and the change and
prone area are evaluated and mapped. Based...
Citations
... Previous studies have suggested that these declines may variously be attributed to: (i) reductions in ood magnitudes on the Mekong River due to climate change [16][17][18][19] ; (ii) reductions in ood season water levels on the Mekong River due to ow regulation by upstream dams 15,[20][21][22] , and urban development (projects for irrigation, ood control, domestic water supply, and navigation) in the Mekong basin 11,16,20 and; (iii) infrastructure development on the Tonle Sap oodplain (road improvements, embankments), σ σ σ σ σ σ which has obstructed water ow from the Mekong River to the Tonle Sap oodplain and prevented it from reaching the lake 9 . However, rainfall and ow measurements do not wholly support the rst two points. ...
The Tonle Sap Lake (TSL), a vital component of the Mekong River, is renowned as one of the world’s most productive lake-wetland systems. The lake’s high productivity is intimately related to an annual flood pulse that is driven by Mekong River flood waters forcing a unique flow reversal along the Tonle Sap River into the lake. During the dry season the floodwaters are returned to the Mekong River, sustaining vital freshwater fluxes to the downstream delta, inhabited by 23 million people. Recent observations have revealed notable changes in the timing and duration of the reverse flow into the TSL, resulting in associated reductions in lake inundation extents. Previous work has identified changes in flow regimes as a possible cause of the observed decline of the reverse flow. In contrast, here we show how riverbed lowering along the mainstem of the Mekong River – driven by accelerating channel bed sand mining and trapping of sediments through upstream hydropower damming – of 3.06 m (σ= 2.03 m), has resulted in a reduction of the water flux into the TSL by up to 47% from 1998 to 2018. We additionally show that projected future (to the year 2038) riverbed lowering, resulting from ongoing sandmining, of up to 5.92 m (σ) = 2.84 m), would result in a further decline of water flux into the TSL of ~ 69% relative to the bathymetry condition in 1998. These ongoing reductions are reducing the maximum extent of seasonally flooded areas by ~ 40% around the lake, presenting a critical threat to its biological productivity and the entire functioning of the TSL flood pulse system. Additionally, these changes in the reverse flow would increase, by around 26 billion m³, the flow that would be transmitted downstream into the Mekong delta during the monsoon season, potentially contributing to increased flood risk downstream as well as reducing dry season ‘return’ water fluxes to the delta by 59%, presenting risks of accelerated saltwater intrusion and reduced agricultural productivity within the delta. Taken together our modelling results show the importance of sediment and river bed levels to the sustainability of the TSL flood pulse and that its future function will be significantly diminished if current levels of sediment extraction from the Mekong system continue.
... The construction and operation of reservoirs in river basins have a significant impact on river flow, sediment transport, channel morphology, and riverine ecosystems 2-7 . Some scholars, after evaluating the impact of dam construction on downstream water conditions, have pointed out that the duration and magnitude of river flow and peak flow change after the construction of dams [8][9][10][11][12][13][14] . After the construction of the Garrison Dam on the upper Missouri River in the United States, the peak flow decreased from an extreme value of 10,279 m 3 /s upstream of the dam to 4390 m 3 /s 12 . ...
... After the construction of the Garrison Dam on the upper Missouri River in the United States, the peak flow decreased from an extreme value of 10,279 m 3 /s upstream of the dam to 4390 m 3 /s 12 . In the Mekong River, reservoirs cause an increase in average monthly flow by 25-160% during the non-flood season (December-May) and a decrease by 3-53% during the flood season (June-October) 13 . Some studies 14-18 evaluating the impact of dam construction on hydrological conditions and sediment transport have found that the construction of dams has led to significant changes in sediment flux in many of the world's major rivers, such as the Mississippi River 19 in the United States, the Nile River 20 in Egypt, the Yangtze River 21,22 , and the Yellow River 23-25 in China. ...
The construction of large reservoirs has modified the process of water and sediment transport downstream, resulting in changes in the morphology of the river cross-section. Changes in water and sand transport and cross-sectional morphology are reflected in the rating curve at the cross-section. This study analyzed the variations in the rating curve at the Huayuankou (HYK) section and their influencing factors, and conducted water level predictions based on this relationship. The findings revealed that while the annual mean water level has shown a declining tendency over the past 20 years, the annual mean discharge has shown a constant pattern. The rating curve at this stretch narrowed from a rope-loop type curve in its natural condition to a more stable single curve as a result of the construction of the dam upstream of the HYK section. The effect of pre-flood section morphology and the water–sediment process on the scattering degree of the rating curve is inverse; increasing roughness and hydraulic radius decreases scattering degree, while increasing sand content and sand transport rate increases scattering degree. Using the measured data from 2020 as an example, the feasibility of predicting cross-sectional water levels using the rating curve was verified. The prediction results were accurate when the flow was between 1000 and 2800 m³/s; However, when the flow was between 2800 and 4000 m³/s, the forecast results were typically slightly lower than the measured values. Overall, the method demonstrates good predictive accuracy. Insight from the method can be used to predict water levels to better inform decision making about water resources management, and flood emergency response in the lower Yellow River.
... NASA, (2021) suggest that under scenario SSP5-8.5, the VMD could experience a mean sea level rise (SLR) of 1 m by the end of the century. This level of sea level rise could contributing to the threat of 75 greater flood magnitudes for the region (Västilä et al., 2010;Lauri et al., 2012;Hoang et al., 2016;MONRE, 2016;Minderhoud et al., 2019). According to Minderhoud et al., (2019), approximately 51% of the VMD plain would be submerged if the mean sea level rose by 0.8 m. ...
The Ca Mau Peninsula plays a critical role in the agricultural and aquacultural productivity of the Vietnam Mekong Delta (VMD), central to regional food security and the population’s economic and social welfare. Unfortunately, this region has also historically been a hotspot for natural disasters, particularly from flooding, which is initiated by seasonal river flux upstream and heightened sea levels downstream, but also exacerbated by global climate change (e.g., increased rainfall and sea-level rise, tropical storm surges) and human activities (e.g. river bed lowering, land subsidence). The potential risks associated with rising inundation levels is important information for the future sustainability of the region and its ability to adapt to both current and forthcoming changes. The research around the influence of such drivers on future flood risk, in the Ca Mau Peninsula, is incomplete, primarily due to the absence of a quantitative coastal inundation map corresponding to future compounded scenarios. In this study, we therefore evaluate flooding dynamics in the Ca Mau peninsula using a fully calibrated 1D model, to represent a range of anthropogenic and climate change compound scenarios. Our findings indicate that factors such as increased high-flows upstream, alterations in the riverbed of the main Mekong channel, and occurrences of storm surges effecting the mainstream Mekong River, are unlikely to significantly affect inundation dynamics in this region. However, land subsidence, rising sea levels, and their combined effects emerge as the primary drivers behind the escalation of inundation events in the Ca Mau peninsula, both in terms of their extent and intensity, in the foreseeable future. These results serve as vital groundwork for strategic development and investment as well as for emergency decision-making and flood management planning, providing essential insights for shaping development policies and devising investment strategies related to infrastructure systems in an area which is rapidly developing.
... Runoff is a basic element of the hydrological cycle, which causes the change of river water regimes. Rainfall contributes to 80-90% of runoff in the LMRB, which is the major factor influencing flood occurrence (Delgado et al., 2012;Lauri et al., 2012;Wang et al., 2022). ...
... °C and by 1.2-8.6%, respectively, for the years 2032-2042 compared to the baseline of 1982-1992 (Lauri et al., 2012). Compared to the baseline of 1971-2000, the daily average temperature during 2036-2065 was predicted to increase by 2.4 °C and 1.9 °C from Representative Concentration Pathway (RCP) 8.5 and RCP4.5 ensembles under CMIP5 climate projections, respectively; while annual precipitation from the two ensembles increased by −3 to 5% (RCP8.5) ...
... The temperature increase tends to be greater in the southern and northern parts of the basin, whereas the patterns for annual precipitation varied with GCMs and emission scenarios but increases were more likely in the Lancang River basin (Hoang et al., 2016;Lauri et al., 2012). Patterns for precipitation changes were different even under the same emission scenario: e.g., the largest increase was in the middle basin for three GCMs, while in the northernmost and southern parts for the remaining GCMs (Lauri et al., 2012). ...
Droughts and floods are the main threats to the Lancang-Mekong River Basin (LMRB) . Drought mainly occurs during the dry season, especially in March and April, in the LMRB. The “dry gets drier” paradigm performs well in the LMRB, specifically in the Mekong Delta. Further, flood frequency and magnitude, which are determined by heavy rain, are also increasing in the LMRB. Droughts and floods show obvious seasonal and regional characteristics in the LMRB . The LMRB is a well-known rainstorm-flood basin. Floods in the LMRB are mainly caused by heavy rain. The LMRB is dominated by regional floods, and basin-wide floods rarely occur. From upstream to downstream, the flood peak and flood volume have shown increasing trends. Meanwhile, moving further downstream, the flood season ends later. In the upstream areas, floods are mainly concentrated in the period from July to October, with the highest probability of floods occurring in August. For the downstream areas, the flood season is from August to October. Climate change is one of the major factors affecting the LMRB’s droughts and floods . Global warming is an indisputable fact. Under global warming, extreme hydrological events show a tendency to increase. Climate models have suggested a future potential for increased flood frequency, magnitude, and inundation in the LMRB by 10–140%, 5–44% and 19–43%, respectively. Although the severity and duration of droughts are also increasing, the differences in drought indicators projected by different climate models are significant. Hydropower development was another major factor affecting droughts and floods in the LMRB . Large-scale hydropower development has drastically changed streamflow characteristics since 2009, causing increased dry season flow (+150%) and decreased wet season flow (−25%), as well as reduced flood magnitude (−2.3 to −29.7%) and frequency (−8.2 to −74.1%). Large-scale reservoirs will have a profound impact on hydrological characteristics, droughts and floods, agriculture, fisheries, energy supply, and environmental protection in the LMRB. Coupling climate models and hydrological models is the main way to study the impact of climate change and reservoir operation in the LMRB . Climate change indirectly affects hydrological characteristics by affecting meteorological parameters, while reservoirs can directly change the propagation from meteorological extreme events to hydrological extreme events by releasing/storing water in different situations. Hydrological models are the link connecting and quantifying the coupled effects of climate change and reservoirs. More studies are needed to develop a comprehensive understanding of the future impacts of climate change and reservoir operation on extreme events in the LMRB, as well as adaptation and mitigation measures.
... Dam infrastructures have been recognized to alter the flow regime of the Mekong (Binh et al., 2020b;Lauri et al., 2012;Lu et al., 2014;Li et al., 2017a;Räsänen et al., 2017). Binh et al. (2020b) analyzed the long-term discharge along the entire Mekong from Chiang Saen to the VMD. ...
In the Mekong Basin, rice plants have low yields because of degraded soils, fresh water is becoming scarce, and rice cultivation consumes a lot of water. Beijing-directed rules to govern the river and its plan to build cascade dams upstream have weakened the Mekong River. The Mekong River Commission was established in 1957, but for over 50 years, the Commission still has only Laos, Cambodia, Thailand, and Vietnam as members. To confront all these troubling trends and challenges and the sustainability of the region, riparian countries in the lower Mekong areas have sought partnerships with support from the USA, Japan, Australia, and Korea. Many water development projects in the Mekong Basin have been researched and implemented by bilateral, transboundary, regional, and international collaborations. Although the collaboration is still not holistic as expected, increasing regional and international collaboration projects conducted recently have provided the bright potential for integrated sustainable water resources development and management in the Mekong Basin. A synthetic review of previous water development projects within the Mekong Basin in this chapter introduces an overview of opportunities and challenges and implies lessons for further water development projects in the future among riparian countries in the Mekong Basin and other transboundary river basins in the world.
... Many studies have highlighted that rice yields increased during the first 20 years of this new infrastructure and intensified regulation of the hydrological regime of delta (Sakamoto et al 2009;Lauri et al., 2012;Tri, 2012;Chen et al., 2012;Tran et al., 2018). The amount of land cultivating triple-rice farming increased, while the land area cultivated for double-rice crops decreased (Sakamotung et al., 2009). ...
Sinking and shrinking, the Vietnamese Mekong Delta is a materialization of dynamic river flows, sediment flows, and coastline processes. Past policy aspirations and extensive water infrastructures have shaped the delta into one the most significant food producing landscapes in Southeast Asia. Yet, these changes have also created new environmental risks by transforming the hydrological system. Research has produced a growing and increasingly diverse empirical literature on the delta's environmental context, without necessarily providing water resource managers, policymakers and practitioners with the information needed to galvanize more resilient development. This focus review presents a detailed overview of the recent scientific findings, exploring how the management of water resources is changing, as well as their inter‐relationship with land use, policy, socio‐economic transitions, and global environmental crises. Compound and systemic risks to the delta include climate change, hydrometeorological hazards, upstream developments and an unsustainable development trajectory. We outline scientific knowledge gaps, as well as the pressing need for sharable analysis‐ready data and innovations. Finally, we provide recommended future research avenues for multiscale actions toward a sustainable and resilient delta future.
This article is categorized under: Human Water > Water Governance
Science of Water > Water Extremes
Science of Water > Water and Environmental Change
... Construction and operation of reservoirs in the LMR basin has a significant impact on river discharge (Hecht et al., 2019). In addition, several drought events have occurred in recent years across the LMR basin (Keovilignavong et al., 2021;Kondolf et al., 2014;Lauri et al., 2012). It is important to monitor changes in reservoir water storage and, hence, quantify the impact of reservoir operation on the redistribution of surface water resources and the mitigation of droughts. ...
The Lancang-Mekong River (LMR) is an important transboundary river in Southeast Asia shared by China, Myanmar, Laos,Thailand, Cambodia, and Vietnam from upstream to downstream. Construction and operation of dams in the LMR basin has profoundly affected its natural streamflow regime. It is therefore important to monitor changes in reservoir water storage and to quantify the impact of reservoir operation on the redistribution of
surface water resources over this basin. Given the difficulty in obtaining in-situ measurements of reservoirs on the LMR, we integrated multisource remote sensing, including satellite altimetry and optical and synthetic aperture radar (SAR) images, to generate weekly water levels and water storages of nine largest reservoirs on the main stem of the LMR from 2017 to 2021. Specifically, partial surface water extent (SWE) of reservoirs was extracted from Sentinel-1 SAR images and digital elevation models (DEMs), using Random Forest algorithms trained by partial SWE derived from Sentinel-2 optical images, showing an overall accuracy higher than 95%. Based on the partial SWE and water level estimates from ICESat-2 and Global Ecosystem Dynamics Investigation (GEDI, International Space Station-based) data, the relationships between water levels and partial SWE were derived to convert partial SWE into water level time series. Furthermore, water storage time series of the nine reservoirs were obtained from water level time series and hypsometric functions derived from SRTM DEMs that were corrected by ICESat-2 data to remove systematic errors. For the Xiaowan Reservoir on the Lancang River, there is close agreement between remote sensing-derived water levels and in-situ water levels in terms of a normalized RMSE lower than 5%. Results indicate that multisource remote sensing has large potential for high-temporal-resolution monitoring of reservoir water levels and water storage. This could more precisely evaluate impacts of cascade reservoirs on the streamflow of the LMR and facilitate drought and flood mitigation for riverine countries.
... Other studies have examined the changes in groundwater, especially over the Mekong Delta or other small regions within the MRB, including those 46,54-56 that have focused on groundwater analysis in the different parts of the basin. Numerous other studies have examined various aspects of hydrology and climatology over some parts of the basin 13,39,41,42,47,57,58 which provide a small-scale or sub-basin level understanding of spatial and temporal variability. Associated nutrient dynamics have also been explored in a number of studies. ...
The Mekong River basin (MRB) is a transboundary basin that supports livelihoods of over 70 million inhabitants and diverse terrestrial-aquatic ecosystems. This critical lifeline for people and ecosystems is under transformation due to climatic stressors and human activities (e.g., land use change and dam construction). Thus, there is an urgent need to better understand the changing hydrological and ecological systems in the MRB and develop improved adaptation strategies. This, however, is hampered partly by lack of sufficient, reliable, and accessible observational data across the basin. Here, we fill this long-standing gap for MRB by synthesizing climate, hydrological, ecological, and socioeconomic data from various disparate sources. The data— including groundwater records digitized from the literature—provide crucial insights into surface water systems, groundwater dynamics, land use patterns, and socioeconomic changes. The analyses presented also shed light on uncertainties associated with various datasets and the most appropriate choices. These datasets are expected to advance socio-hydrological research and inform science-based management decisions and policymaking for sustainable food-energy-water, livelihood, and ecological systems in the MRB.
... The flow regime of the Mekong River, which is one of the largest river systems worldwide and most important food-producing regions in Southeast Asia (Boretti, 2020), has been significantly altered (Lauri et al., 2012;Lu et al., 2014;Binh et al., 2018;Hecht et al., 2019;Binh et al., 2020aBinh et al., , 2020c, with the suspended sediment load (SSL) being substantially reduced (Kummu and Varis, 2007;Kondolf et al., 2014b;Binh et al., 2020b). Six mainstream dams in the Lancang cascade (upper Mekong basin) have reduced the SSL by 50-94 % along the lower Mekong River (Kummu et al., 2010;Kondolf et al., 2014b;Manh et al., 2015), and sixty-four completed dams in the Mekong basin were responsible for a 74 % SSL reduction in the VMD (Binh et al., 2020b). ...
Flow, suspended sediment transport and associated morphological changes in the Vietnamese Mekong Delta (VMD) are studied using field survey data and a two-dimensional (2D) depth-averaged hydromorphodynamic numerical model. The results show that approximately 61–81 % of the suspended sediment load in the Hau River during the flood seasons is diverted from the Tien River by a water and suspended sediment diversion channel. Tidal effects on flow and suspended sediment load are more pronounced in the Hau River than in the Tien River. The results show the formation of nine scour holes in the Tien River and seven scour holes in the Hau River from 2014 to 2017. Additional six scour holes are likely to form by the end of 2026 if the suspended sediment supply is reduced by 85 % due to damming. Notably, the scour holes are likely to form at locations of severe riverbank erosion. In the entire study area, the simulated total net incision volume in 2014–2017 is approximately 196 Mm³ (equivalent to 65.3 Mm³/yr). The predicted total net incision volumes from 2017 to 2026 are approximately 2472 and 3316 Mm³ under the 18 % and 85 % suspended sediment reduction scenarios, respectively, thereby likely threatening the delta sustainability. The methodology developed in this study is helpful in providing researchers and decision-makers with one way to predict numerically the scour hole formation and its association with riverbank stability in river deltas. Of equal importance, this research serves as a useful reference on the role of water and suspended sediment diversion channels in balancing landforms in river-delta systems, particularly where artificial diversion channels are planned.
... This could also be considered as the combined impact of the ongoing climate change and irrigation diversions as well. Several research studies were conducted to evaluate the consequences of climate change on river flow in the Mekong basin (e.g., Kang et.al., 2022;Sridhar et al., 2019;Thompson et al., 2013Thompson et al., , 2014Lauri et al., 2012;Kingston et al., 2011), but only a few have looked at the combined effects of dams and climate change on sediments. (Bussi et al., 2021;Khoi et al., 2020;Khoi & Thang, 2017;Shrestha et al., 2013). ...
The Mekong River Basin (MRB) is famous for its rice farming and export and produces more than 20 million tons of rice per year. Rice production depends on climate, irrigation, soil fertility. However, this region is adversely impacted by several environmental concerns like nutrient deficiency from sediment and saltwater intrusion. The decrease in sediment deposition in the Mekong basin is caused by a number of factors. In China, Lao PDR, and Vietnam, the hydropower generation from dams has improved people's overall living standards, leading in more dams being built or planned in the future. However, dam construction work is adversely impacting the overall salinity condition in this region by reducing upstream flow. Upstream lower flows during the dry season contributes to the increased salinity in the lower Mekong Delta. In addition to these, multiple dams in the upper and middle region of the Mekong basin are trapping sediments and decreasing it in the lower zones. This study found that the reservoirs, built by China between 2008-2015, has reduced the sediment load at all five stations considered in the study. When a reservoir is removed from the model, the sediment load is increased which showed the substantial impact of reservoir construction on sediment load in this area.
The landuse pattern is another factor for variability of the sediment yield in the study area. Forest area contributes to higher sediment production whereas agricultural area results in lower sediment yield. The GFDL RCP (4.5) and GFDL RCP (8.5) future climate change projection scenarios used in this study also demonstrated substantial variability in the precipitation pattern for the study region. GFDL RCP (4.5) scenario resulted in a lower sediment yield during the dry season. On contrary to that, GFDL RCP (8.5) showed higher sediment yield due to higher precipitation during the wet season. The severe salinity impact was observed in the Cai Nuoc, Nam Can, and Thanh Phu districts. In Ca Mau province, the observed salinity is highest among the provinces of the study area during dry season (February to May), about 12-14 PPT (parts per thousand) whereas the lowest level of salinity (less than 1 PPT) was observed in the Dong Thap and Vinh Long provinces.
This salinity intrusion is adversely impacting the rice production in the study area. In the year 2000, rice production in the Ca Mau province was about 100-150 thousand tons. But salinity intrusion is drastically reducing the rice production in this area, about 10-30thousand tons per year during 2015-2017. Rice production is increasing in the upper deltaic part of the Mekong Delta region where preventive measures were taken.
