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Assessment of water quality along a tributary of the Mekong river in a mountainous, mixed land use environment of the Lao P.D.R.

Abstract : In the Lao PDR 78% of the population are classified as rural and efforts to improve access to potable water and sanitation infrastructures are reaching limited areas, these inhabitants may be particularly affected by water quality-related hazards. The objective of this study was to complete a preliminary assessment of stream water quality, at the community-level, using a set of field indicators (i.e. oxygen content, total bacteriological flora and suspended load). Our findings concluded that the water quality is extremely variable depending on the location along the stream and the prevailing rainfall and water flow conditions. Changes in water quality were affected by an uncertain balance between potential self-cleaning processes in the stream environment and human pressure in the riparian zone (i.e. urbanization, riparian vegetation removal, wastewater discharges, stream flow extractions). Several interesting observations were noted that influence water quality: (i) high bacteria and turbidity levels were related to free ranging livestock roaming near the stream in isolated areas; (ii) very low oxygen content and high bacteriological contamination downstream of small remote villages due to low stream discharge and poor sanitation conditions; (iii) high bacteria levels along continuously urbanized reaches; (iv) low oxygen content following organic-rich wastewater inflows from a small agro-factory; (v) very high suspended load and bacteria levels during flood events due to soil erosion of steep cultivated hillslopes. Besides pollution related to these human activities we also noted “naturally” metal-rich stream water when crossing swampy areas fed by dysoxic groundwater. We propose a set of pro-poor recommendations to improve or maintain good stream water quality in the uplands and for environmentally friendly management of surface water resources.
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Contributor : Henri Robain <>
Submitted on : Wednesday, June 17, 2009 - 11:31:26 AM
Last modification on : Wednesday, June 16, 2021 - 3:48:49 AM


  • HAL Id : bioemco-00396226, version 1


Olivier Ribolzi, Juliette Cuny, Phonexay Sengsoulichanh, Alain Pierret, Jean Pierre Thiebaux, et al.. Assessment of water quality along a tributary of the Mekong river in a mountainous, mixed land use environment of the Lao P.D.R.. Lao Journal of Agriculture and Forestry, 2008, 2008 (MSEC Management of Soil Erosion Consortium special), pp.91-111. ⟨bioemco-00396226⟩



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