Remote sensing and GIS applied to the study of aquaculture development and mangrove forests: A case study in the Giao Thuy district, Vietnam (French text)

Aquaculture is growing more rapidly than all other food producing sectors. Shrimp culture is a sector of aquaculture which has a high potential for poverty alleviation and rural development in Vietnam. Unfortunately, some of the changes induced by the shrimp farm on the environment have potential negative impacts, one of which is wetland deterioration. Despite the rapid growth of aquaculture and the evolution of the consciousness about its environmental hazards, few studies have considered this matter in an objective manner. Spatial observation and geographic information systems (GIS) have been applied in this study to the analysis of resource alteration caused by aquaculture development and its future development planning in the district of Giao Thuy, Nam Dinh province, Vietnam. Three Landsat images were processed and classified; the detected changes between classifications were then rigorously verified by a validation algorithm. The selected images acquisition years are 1986, 1992 and 2001. The analysis of the results leads to the following observations: 63% of mangrove areas existent in 1986 were replaced by shrimp ponds; between 1986 and 1992, 440 ha of mangrove were destroyed, but between 1992 and 2001 the extent of the mangrove increased by 441 ha, restoring it approximately to its 1986 level; this recovery is attributed to reforestation projects and to natural regeneration promoted by conservation efforts in an approximate proportion of 58% and 42% respectively. A second part of the study examines the ongoing intensification of the production methods process as well as the required planning. GIS is used to produce a site suitability map for sustainable development of aquaculture in the Giao Thuy district.