Land Use Changes in the Deltas

Partly as an adaptation process to salinity intrusion, intensive saline (commercial/family shrimp farming) and extensive brackish water (polycultures and rice-shrimp farms) aquacultures are nowadays one of the most dynamically growing sectors in Vietnam and increasingly co-occur within formerly rice dominated areas (Joffre & Bosma, 2009). With an annual percentage growth rate of 21% (FAO, 2008), Vietnam became one of the largest fishery export countries in the world (FAOSTAT, 2013), whereby the overwhelming majority of the farmed shrimp (81%) and farmed fish (89%) are produced in the Mekong and Red River deltas (GSO, 2010). However, this type of farming is risky for farmers due to high investment requirements and its high vulnerability to diseases, market price fluctuations, and varying salinity levels. Furthermore, such land use systems are often characterized by a pronounced and sometimes heavy use of agrochemicals. Furthermore, there is a risk of cross contaminations with of agrochemicals in areas were different land use systems are closely adjacent.
Beside vulnerabilities related to land use changes, some farmers maintain rice production but sell their topsoil to extract clay for brick production (see figure 2 below) in order to generate short term income and, thus, risking long term productivity losses of their soils (Guong et al., 2011; Vietnamnews, 2013).

Shrimp farming Systems
Figure 1, Different intensification levels of shrimp farming systems: Extensive shrimp system (a), high intensive shrimp system (b). Diversity of adjacent land use systems in salt water effected coastal areas with risks of cross contamination from pesticides and antibiotics: Shrimp only system directly adjacent to vegetable farming systems (c), intensified shrimp only system directly adjacent to rice-shrimp system (d), fresh water fish farming surrounded by rice fields © DeltAdapt © Universität BonnAllgemeine Bodenkunde und Bodenökologie
Soil selling
Figure 2, Soil selling in Tra Vinh Province: Ditch in the rice field for transposition of excavated soil and frist machining of soil monoliths (b). Sequential steps of top soil removal from soil excavation in the rice field (b), first transportation of soil monoliths in the ditch (c), and over long disstance via the river to the brick factory (d), machining of soil monoliths (e) to raw bricks (f) and finished bricks in front of a number of brick factories. © DeltAdapt © Universität BonnAllgemeine Bodenkunde und Bodenökologie
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