Water resources and land use management
Climate change projections for the Mekong Delta.
In the Fourth Assessment Report from IPCC (2007), the coastal Mekong Delta is mentioned as a hotspot for climate change, with an extreme relative vulnerability (more than 1 million people directly affected by 2050) to coastal erosion and land loss, primarily as a result of decreased sediment delivery by the rivers, but also through accentuated rates of sea-level rise with impacts exacerbated by human pressures.
Climate change has been posing a greater flooding threat to the Mekong Delta as a result of rising sea levels near low-lying land at the mouth of the delta and increased rainfall. Among the climate change impacts experienced to-date, the Mekong Delta has experienced a 30% annual increase in rainfall, shifting rainfall patterns, an average temperature increase of 0.5oC over the last 30 years, and an average sea level rise of 3 mm per year over the last 30 years. The impacts of climate change are predicted to be more severe in the coming years, with projected increases in average temperatures of 1.1oC to 3.6oC as compared to average temperature during the 1980-2000 period. The average level of sea level rise is estimated at 28-33cm by 2050 and 65-100cm by 2100.
Furthermore, the maximum flow of the Mekong is estimated to increase significantly, while the minimum monthly flows are estimated to decline, leading to increased flood risks during wet season and an increased possibility of water shortages in dry season.
The projected impacts of climate change present a serious threat to the agricultural productivity of the Mekong Delta, which will negatively impact the livelihoods of many of its residents due to the importance of agriculture to this region. According to climate change scenarios, 90% of the agricultural land in the Mekong Delta could be affected by flooding and 70% of the Mekong Delta could suffer from saline intrusion as a result of climate change.
The main challenges and risks related to water resources management and land use planning in the Mekong Delta can be categorized for two hydrological zones:
Inner delta plain: upper delta and middle delta
Since the Doi Moi renewal policy, Vietnam has pursued a “rice first policy” that aims at maximizing rice production for export and domestic food supply. At present, a total of more than 800,000 hectares is used for triple crop rice harvesting in the delta. To enable the cultivation of the third rice crop during the flood season, high dykes are built in the upstream floodplains of the delta, which keep the floodwaters out.
The presence of these high dykes has altered the hydrology of the delta in a major way, as a large part of the floodplains in the Long Xuyen Quadrangle have lost their floodwater absorption and retention capacities. The resulting decrease in sediment disposal leads to higher production costs from increasing use of fertilizers and agrochemicals, resulting in reduced water quality in rivers and canals in rice farming areas. The high dykes also prevent fish fingerlings from entering the floodplains, resulting in increased vulnerability for poor households that are the most dependent of captured fisheries.
The high dyke system combined with sea level rise amplifies flood risks in the middle delta in years with high river discharges, leading to an increasing demand for capital-intensive flood protection measures in urban and industrial areas.
Outer delta plain: estuaries and peninsula.
In the delta peninsula area, groundwater levels are continuously falling due to overexploitation of groundwater aquifers as an additional source of fresh water to control salinity levels in shrimp farming and to enable the diversification of production into vegetables and homestead production (both in rice and shrimp areas). In the dry season, groundwater levels already drop to 15-20m below the surface. There are strong indications that depleted ancient (Pleistocene) are not (or very limited) replenished from surface waters. This raises the concern that future groundwater use is highly unsustainable.
In addition, recent research provides evidence that land subsidence related to groundwater extraction has gradually accelerated in the past decades with highest sinking rates at present. Current average subsidence rates due to groundwater extraction in the best estimate model amount to 1.1cm/yr., with areas subsiding over 2.5cm/yr., thus outpacing sea level rise by an order of magnitude. As a result, subsidence acts as a catalyst, increasing vulnerability to storm surges and saltwater intrusion in the channels.
Satellite monitoring shows large-scale shoreline erosion and land losses between 2003 and 2016 that now affects over 50% of the once strongly advancing >600 km-long delta shoreline. The erosion pattern, with no identified change in the river’s discharge and in wave and wind conditions over this recent period, is consistent with: (1) a reported significant decrease in coastal surface suspended sediment from the Mekong basin that may be linked to hydropower dam retention of its sediment, (2) large-scale commercial sand mining in the river and delta channels, and (3) subsidence due to groundwater extraction. In the coastal area of Ca Mau and Kien Giang, the sea dyke system with an average height of 1,2m still provides adequate protection for most districts, however longterm vulnerability is assessed high and shoreline erosion is already resulting in first resettlements of coastal populations.
The Mekong Delta has a mangrove forest area of about 50,000 ha. Due to erosion and cutting forest for aquaculture and inshore fishing, the loss of coastal mangroves is around 500 ha/yr (about 1%) and many coastal parts of Bac Lieu, Ca Mau and Kien Giang have no mangrove forest belt seaward of the sea dykes. The area used for aquaculture increased dramatically from a total of 200,000 hectares in 1995 to approximately 750,000 at present. Untreated wastewater from aquaculture, especially intensive shrimp ponds, is released directly into the adjacent waterways, creating local conflicts between water users, and affecting coastal fisheries.
The coastal water around the Mekong Delta, known as the Mekong Plume, receives the Mekong outflows and influences the hydrology of the delta through its tidal effects. It is estimated that out of the 160 million tons per year of the Mekong sediment load, about 100 million tons and 16,000 tons of attached nutrients reach the coastal plume annually, not including the sand load. The freshwater outflow influences salinity levels and suspended sediments and nutrients, and sand loads reaching the coastal water play a vital part to the geo-morphological formation of the delta, maintaining and advancing the coastline, and supporting the productivity of the coastal fisheries.
The annual fish catch in the coastal waters of the delta is about 500,000-700,000 tons per year, employing about 25,000 fishing vessels, thus constituting a significant component of the delta economy. However, fisheries' indicators and surveys for Soc Trang, Bac Lieu and Ca Mau provinces already show downward trends and indicate that 70% of catched are composed of young and immature fish and catch rates from trawler fleets show a 30-40% decline in shrimp catches. Up to date, the importance of the coastal waters has been poorly recognized in development planning for the delta.
Socio Economic Development.
Transportation and Logistics.
The region's strategic freight transport needs are met by the inland waterways and the road system.
There is a significant inter-relationship among the inland waterway network triangle formed by the MD, greater HCMC, and Ba Ria-Vung Tau. A considerable portion of the Delta’s agricultural output is processed in HCMC, and a significant part of delta-related trade and transportation is run from there. Ba Ria-Vung Tau has a range of deep water port facilities, located at Cai Mep-Thi Vai, that are expected to become the main seaport of greater HCMC. Yet, the exact nature of the movement of freight in this economically-critical triangle, which is characterized by an intricate network of rivers, canals, local roads, national roads, and coastal routes, is poorly understood due to a general lack of quantitative measuring of actual freight flows.
Despite its economic significance, the delta faces several challenges if it is to sustain its track record of growth, job creation, and export origination going forward. Many of the region’s main transport arteries and nodes across modes suffer from supply-demand mismatches in infrastructure provision and service delivery. These have primarily resulted from sustained underinvestment in capital and maintenance expenditures for the waterways and road links, and from fragmentation in decision and policy making to better integrate and promote the efficiency of logistics operations in greater HCMC, particularly as to more effectively linking it with the Mekong Delta and the gateway province of Ba Ria-Vung Tau.
Most inland waterway transport activities in the delta and greater HCMC area utilize a combination of major river channels - the Mekong, Bassac, Soai Rap, and Dong Nai rivers - and purposefully built canals. While the delta's waterway network is vast and intricate, a select number of key canals, which have less freight-carrying capacity and are more exposed to siltation than the main river channels, have increasingly become bottlenecks for supply chains linking Tien Giang, Long An, Binh Duong, Dong Nai, and Ba Ria-Vung Tau provinces.
The Mekong Delta is the third most important industrial region, contributing roughly 10% of the industrial production (GSO, 2011) yet since the mid-1990s the delta is not able to increase its relative contribution to the overall industrial production of the country. Consequently, the contribution of the industrial sector to the regional GDP is still far below the respective contribution at the national level and expectations formulated in development master plans, meaning that it can only to a limited extend unfold the potential to absorb the workforce released by the agricultural sector following intensification and transformation. Currently, around 30% of the Delta's GDP is generated by industry especially food processing, the production of agricultural and aquaculture inputs (e.g. fertilizers, pesticides, seeds, fish feed) and related industries in equipment and machinery. The agro-processing chain - which can be considered the base for developing regional innovation - is characterized by exports largely comprising unprocessed or semi-processed goods which have low added value and cooperation, exchange and synchronization between different actors and levels in the value chain is still in its infancy. Besides that, low-technology manufacturing such as textile industries and building material production play a major role. Within the Mekong Delta, the industrial production is highly concentrated, with Can Tho, Long An and Kien Giang provinces accounting for half of the industrial production.
To date, the Mekong Delta seems not able to fully profit from the proximity to HCMC and relocation of industrial sites due to increasing agglomeration costs in the same way as the provinces located north east of the city. Main restrictions are the lack of positive cluster advantages, insufficient transportation infrastructure and insecurity with respect to the availability of qualified workforce, as the general education level in the Mekong Delta is falling behind the national level and primarily supports and reinforces low-profile industrial production. Attracting substantial FDI would however require an increase of higher-skilled work force.
In general, industrial zones and parks suffer from lower-than-average occupancy rates (<30%). And although land conversion for industrial use has negative social impacts such as an increase in outmigration, plans for the further development of industrial zones and parks are undeterred with 30 million hectares of potential fertile land converted to largely empty industrial zones.
Outmigration and urbanization.
Over the last years, the Mekong Delta has experienced a drastically increasing trend towards cross-regional outmigration, with the majority migrating to HCMC in search for employment while remaining relatively close to their home provinces. Within the delta, Can Tho is the only province experiencing net in-migration.
The strong outmigration results to a large degree from the economic transformation process in the rural area, with many farmers pushed into landlessness and high numbers of work force shifting to urban centers for non-farm income generation.
Urbanization has been important not only for providing central places with social and cultural functions such as healthcare and education, but also for facilitating economic growth and initiating the transition towards development of the secondary and tertiary sectors. In most cities, the strong urban growth has exceeded the capacity for adequate infrastructure planning, with a neglect of socially inclusive development and an insufficient legal framework for land regulation. The current masterplans on socio-economic development envisage further development of industrial zones, but urban planning seems to be relatively uncontrolled (not demand-oriented and competing at district and/or provincial level) with climate change impacts increasingly uncovering shortcomings from insufficient integration and static urban planning and management. Most migrants will probably not be able to enter into the currently developing housing market focusing mainly on upper and middle-class population, and will likely to have difficulties in finding infrastructure meeting their needs.
Municipal solid waste is increasing quickly and has become one of the most serious environmental problems in Mekong Delta. The region produces about 5% of the total amount of solid waste in Vietnam. Collection rate of solid waste are quite high in the larger cities (approximately 70%) and rather low (<50%) in the rural areas, with uncollected waste illegally disposed on unused land, rivers and canals.
Under the national electricity development plan, coal thermal power will make up 50 percent of Vietnam’s total electricity output from 2020, with the Mekong River Delta becoming one of the nation’s thermal power centers. It is expected that 14 coal plants will be developed in the region by 2030 which would have total capacity of 18,268 MW: four in Tra Vinh, one in Bac Lieu, two in Hau Giang, two in Long An, three in Soc Trang and two in Tien Giang. Once operational, these power plants are expected to cause strong adverse impacts on the environment (air pollution, degradation of water quality), thus reducing agriculture and aquaculture productivity in Mekong Delta. Further development of renewable energy seems vital to ensure that high growth and annually increasing energy demands can go hand-in-hand with environmental sustainability.
Upstream developments are expected to cause severe impacts on the delta. At present, seven dams have been built in the Upper Mekong Basin (UMB) in China. Another 11 dams are being planned on the mainstems of the Mekong in the Lower Mekong Basin (LMB). The potential impacts of the upstream Mekong dams on the delta include impacts on sediments, fisheries, and flows. Data from the Mekong River Commission (MRC) show that after the construction of the 7 dams in the UMB, the annual suspended sediment load of the Mekong has reduced by 50% from 160 million tons in 1992 to 85 million tons in 2014.
The Strategic Environment Assessment commissioned by the MRC in 2010 projected that the annual suspended sediment load would be halved again to 42 million tons after the completion of the 11 dams in the Lower Mekong Basin. The dams will also trap 100% of the bedload (sand and gravel).
The reduction of sediments, especially the suspended sediment is expected to have significant impact on the soil fertility and farming costs in the Mekong Delta. The reduction of the bedload will cause impact to the river morphology and the coastline.
The dams, especially the 11 dams in the LMB are projected to have serious impact on the wild capture fisheries in the delta. It is projected that after the construction of the 11 dams, 100% of the white fish populations in the delta will disappear due to barrier effects of the dams that prevent the fish from migrating upstream for breeding. The disappearance of the white fish species will have serious implications to the food chains of the wetlands ecosystems of the delta and affect nutrients and health of people in the delta, especially the rural poor. The productivity of the coastal fisheries is also expected to be affected with the reduction of the sediment-attached nutrients that the river brings out to the coastal Mekong Plume water annually.