Limpieza, Desinfección, Utensilios y Equipamiento:

Flooding and saline intrusion have manifold and significant impacts on the Mekong Delta. These impacts shape the society and economy in both positive and negative ways. On the positive side, there are so called “beautiful” flood years where flooding occurs but flood levels do neither exceed alarming levels nor remain lower than required for gaining a livelihood (Nguyen Huu Ninh 2007). In these years floods supply fresh water and natural fertiliser for agricultural activities, help flushing out accumulated toxins in the soil, and increase fish resources. Moreover, they improve access to fresh water for domestic use and improve navigation and transport (Nguyen Huu Ninh 2007: 6; Hashimoto 2001; Le Anh Tuan et al. 2007: 41). These are all benefits that are significantly reduced when flood levels are lower than normal. In recent years much of the positive effect of floods did not materialise for exactly this reason.

Similarly, salinity has benefits to the social-ecological system of the Mekong Delta. It is the basis for highly valuable ecosystems. The Vietnamese Mekong Delta possesses, for instance, the largest wetland forest in the whole Mekong region which is rich in biodiversity and provides a multitude of ecosystem services (Le Anh Tuan et al. 2007: 41). Mangroves, for example, provide services such as the protection against storm damages and erosion (USAID 2013: 188). Furthermore, saline water conditions are an important prerequisite for making a living. In particular, the rise of aquaculture in the coastal areas highlights the significance of brackish water environments for sustaining local livelihoods and generating substantive revenues (see section 3.1.2). A study by To Phuc Tuong et al. (2003) showed, amongst other things, that it was the poorest who suffered most from salinity control as the fishery resources, their primary livelihood basis, declined substantially. Saline intrusion also has a positive effect on soil quality. It reduces acidity in potential acid sulphate soils, a major limiting factor for agricultural productivity in some coastal regions (see section 3.1.1). A case study in Ca Mau Province by Thang Nam Do et al. (2005) found, for example, that fisheries, aquaculture, timber, fuel wood, Nypa palms30 and medicinal plants have an average value of more than VND 7.5 million

30

Nypa palms are plants which grow in a mangrove biome and provide multiple services to the people in the Mekong Delta. The leaves are used to build the roofs or walls of thatched houses and the pulp is basis for making juice, sugar or alcohol (Thang Nam Do, Bennett 2005).

(around 380 Euro31) per ha per year. Aquaculture amounts for 48 per cent of total direct use values. The implementation of a high number of sluice gates and prolonged closure times at many gates has seriously threatened the provision of salinity-related environmental services.

Nevertheless, flooding and salinity are better known for their more threatening side. This is particularly visible when looking at the effects on agricultural production - the most important source of livelihood for people in the Mekong Delta. In years of high water levels, flooding causes substantive production losses. Although agricultural production areas have increasingly been protected from floods by dikes (see section 3.1.2), high water levels still pose a serious threat to crop production. The feeling of protection, combined with the public promotion of rice, has led to an increasing number of people cultivating rice and other crops in the flooding season. This has led to substantial losses in case of dikes breakages. Moreover, the intensification policy and agricultural advancements have induced a rise of high yielding but also more flood-sensitive rice varieties. During the floods of 2011, 24,000 ha of rice were damaged, of which 11,000 ha were totally destroyed. This caused an estimated economic loss of 250 billion VND (ca. 8.7 million Euro32) in the Mekong Delta (CFSC 2011). Most affected were the Northern provinces. In the coastal areas severe losses were mostly experienced due to tidal flooding (yet reinforced by riverine flooding). They did not only bring about crop damages due the state of being submerged but also due to the saline nature of the water in the fields. In 2013, high tides damaged, for instance, 60 dikes and submerged thousands of hectares of fruits and other crops in Tra Vinh province (VNN 2013).

Moreover, saline intrusion has serious implications for agricultural production. Most crops, especially rice, can tolerate saline irrigation water and soil conditions to only a small degree. Four grams per litre is often described as the critical threshold for crop production (Le Anh Tuan et al. 2007: 41; Tran Duc Thanh, Pham Van Luong 2000). Beyond this point, rice production is no longer possible (except for some more saline-resistant varieties); more saline-tolerant crops such as sugarcane and corn are substantially inhibited in their growth (NSW - DPI 2006; Omani 2005). A further point to consider is the duration and timing of saline intrusion. The earlier saline water intrudes within the production phase and the longer the saline water stays in the field, the more detrimental the impact on plant growth (Dang Kieu Nhan et al. 2012). Despite major developments in saline protection infrastructure agricultural production in particular still carries a high risk of salinisation. According to the Ministry of Agriculture and Rural Development (MARD 2011, in Dang Kieu Nhan et al. 2012) 100,000 ha out of 650,000 ha of rice production in the lower delta region are still at high risk of dry season saline intrusion.

In addition to agriculture, tidal flooding and saline intrusion have serious implications for other aspects of life. They cause, for instance, infrastructure-related costs. Floods submerge infrastructure and saline water leads to the increased corrosion of metal materials. This does not only cause maintenance and reparation costs but also hampers transportation, trade and communication because roads are often impassable for long periods (Hashimoto 2001). Moreover, saline intrusion severely limits the use of canal water for domestic and industrial purposes (Le Anh Tuan et al. 2007: 42). Epidemic diseases like dengue fever, diarrhea or malaria occur more frequently during severe floods and affect human health more adversely than in other seasons of the year (Nguyen Huu Ninh 2007: 6).

There has been a range of studies dealing with the expected impacts of climate change on Vietnam and the Mekong Delta (USAID 2013; IFAD 2011; Gebretsadik et al. 2012; World Bank 2010; MONRE 2009a). All studies agree on the fact that the predicted changes in climate will have a detrimental effect on rural livelihoods. The agricultural sector is most substantially affected by climate change, according to the MONRE (MONRE 2009a). The ministry assumes a reduction in the value added by

31

At an average exchange rate of the year 2005. 32 _{At an average exchange rate of 2011.}

nearly six percent until 2050 in the whole of Vietnam, whereby the Mekong Delta will be most severely affected. The other sectors are estimated to improve their value added. The changes in flooding and salinisation are important drivers of these impacts. Changes in flood inundation depth, duration and frequency are major factors that reduce both the production area and the crop yields in the Mekong Delta. According to a study by the World Bank (2010a: 19), inundation in the flooding season in the event of a sea level rise of 30 cm by 2050 would lead to the loss of 193,000 ha of the whole rice production area in the VMD (without adaptation). Moreover, large rainfall intensity and unexpected flooding would temporarily (from a few days to several weeks) reduce the saline concentration of seawater which is expected to lead to the dying of dual crust molluscs (bivalvia) such as clams and oysters. These are important sources of livelihood in the coastal areas of the VMD, especially for the poor. In addition to this, sea level rise is expected to decimate mangrove forests in coastal areas. This will most likely affect the provision of ecosystem services in an adverse way (e.g. the commercial and domestic use of wood and fish resources, or the improvement of soil quality for agricultural production). Besides the impacts on agriculture and ecosystem services, the changes in flooding will also increase the impact on infrastructure, water availability for domestic and industrial usages, and human health (MONRE 2009a; World Bank 2010a). Furthermore, a rise in saline water conditions would decrease the areas of freshwater aquaculture in the coastal areas of the Mekong Delta. In addition to this, progressing saline soils and saline irrigation water is expected to reduce the land available for crop cultivation and diminish agricultural productivity in vast areas of the delta. The World Bank (2010a: 19) estimates that, without adaptation, around 70% of the agricultural production area in the Mekong Delta would be impacted by salinity of more than 4 g/l in the dry season. This would lead to a loss of 294,000 ha of rice production (World Bank 2010a: xiv).