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Abstract:
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Ecosystems of estuary and coastal zones are some of the extremely sensitive ecosystems, they can be greatly changed while influenced by natural impacts such as waves, wind, floods and so on and other impacts of natural resources exploitation activities for the development of economics. Xuan Thuy is recognized as the earliest Wetland Nature Reserve and Ramsar Site that was established in 1986. Annually Xuan Thuy receives and makes millions tons of alluvial altered in better texture for mangrove communities grow and develop, moreover it also accepts organic and inorganic compounds from Ba Lat estuary, stands series of storms and tsunamis from nature, especially, every year Xuan Thuy welcomes thousands of migratory bird to stop by, wintering, reside and develop, and among them is Black-faced Spoon Bill (endangered species).
Research and assess variability by remote sensing and GIS (Geographic Information System) methods allow researchers avoid the limitations of traditional methods.
By using the map of topography, material of air photo and data of field verification to study the variability of natural resources in Xuan Thuy Nature Reserve we perceive that:
1. Remote sensing and GIS methods allow to study objects in comprehensive and direct ways, they can be implemented quickly, in multi-time space and with objective characteristics. The updating, separating and exporting information work can be completed in short period of times, the outcome exhibits clearly, easy to use and has high degree of accuracy.
2. The Xuan Thuy National Park from 1986 to 2000 has variability as follows:
- The brackish environment gradually replaces the salty environment; this process of success is demonstrated through a series of economic activities such as aquaculture farming, dykes and shrimp pond’s banks building up…
- The rate of alluvial sedimentation that happens in southwestern of the Park (twin dunes) brings about the development of young mangrove forest area in new deposit alluvial place.
- The area of shrimp ponds is expanded; the bank system is rapidly build up to serve for aquaculture farming. The area of land tenure occurs in many places due to the changes of scale and objective in natural resources use.
3. The causes of the variability that mentioned above can be divided into 2 groups:
- The groups of natural factors, this is the success rule of deposit alluvial areas in estuary and coastal zones.
- The groups of human factors that have occurred from the activities of people who pursue for their livelihood. |