Valuation of the rice sector in the Quang Dien district, Vietnam : A case study of the rice sector in three communes in the Quang Dien district Thua Thien Hué Province, Vietnam

The Tam Giang - Cau Hai lagoon is the largest of its kind in South East Asia and covers an area of 22,000 ha. The lagoon is located in the area with the highest rainfall in Vietnam; there are two main seasons, a dry and a wet season. Seasonal problems to the productivity of rice can thus change from flooding, to drought and salinity intrusion. The water quality in the lagoon is very different over the seasons, due to the mixing of the water from the main rivers in the area, with water from the sea in the lagoon. Over the last two decades, aquaculture extension inside the lagoon and an increased urban use of water has caused less water to flow into the lagoon. The uncontrolled extension of aquaculture ponds has also caused a lack of water circulation, which is especially a big problem for ponds with concrete dikes. This has caused a deterioration of the water quality inside the lagoon, which has negative consequences for the aquaculture sector. The decreased inflow of freshwater is also causing the brackish water inside the lagoon to move more land inwards, what is causing salinity intrusion in lagoon bordering communes. To improve the inflow of freshwater there are three new dams being created in the river basin. This should help to stabilize and restore the ecosystem and gives extra opportunities for irrigation. A salinity intrusion barrier has also been created and the sea-outlet will be enlarged to further increase the circulation of water. Most people in the lagoon bordering communes depend for the main part of their income on agriculture and aquaculture. The high food price and the failure of many aquaculture and agriculture crops nowadays place many farmers under difficulties and they will remain to live below the poverty line. To improve the livelihood of farmers, new water infrastructure will be created and the effect of these new dams and flood protection on the rice sector in different communes will be assessed in this thesis. Three communes have been studied and five main factors have been taken into account which could influence the productivity of rice: variety, soil type, state of the irrigation system, input of chemicals and input of nutrients. Differences in these factors cause different yields, but are also related to each other. Certain varieties of rice are only suitable for certain soils and the soil type is impossible to change. GIS maps have been made of the above factors in the different areas together with the main limitations