Landscape Changes and Loss of Ecosystem services of Houay Mak Hiao River: a Study in a Rapidly Developing City (Vientiane, Laos)

Abstract: This project was conducted in Vientiane, Laos where wetlands, channels and rivers play an important role for the water quality maintenance. Now, large landscape changes like backfilling of wetlands and channelization is affecting the condition of the urban waters which has become extremely polluted. For that reason this survey has focused on the past and present status of Houay Mak Hiao River, who receives basically all drainage water from the city. The purpose of this project is to find out how the condition of Houay Mak Hiao River has changed over time and to describe how historical and current landscape changes have affected the river. Group interviews were conducted in seven villages along the river to find out about the past and present status. The groups consisted of 3-6 respondents in each village. To get as relevant answers as possible, elders, fishermen, farmers and the head of village in each village were participating in the interviews. Water samples were collected at nine sampling sites to determine the water quality of today. The results show that the condition of the river started to significantly decrease about ten years ago and has since then become worse and worse. Today, the water is extremely polluted which has affected the fish population and the vegetation along the river in a very negative way. The deterioration can be connected to channelization and wetland area loss in Vientiane.The level of contamination decreases closer to the outflow into Mekong River which can be due to uptake by floating plants and dilution effects.