Your search found 15 records
(Location: IWMI HQ Call no: IWMI 333.91 G708 SEN Record No: H040865)
To provide data that are lacking at the catchment scale, outflow and sediment yield have Been monitored from 8 small (0.5-64 ha) rural catchments since 2001 in northern Lao PDR. Soil conservation strategies have been developed and tested on three of these catchments. Results clearly show that sediment yields can be reduced from 5-11 Mg ha-1 yr-1 under the current slash and burn system to nearly nil when appropriate practices are selected. These include improved fallow systems based on legumes. These innovative practices rehabilitate degraded land and enhance water quality.
2 Sengtaheuanghoung, O.; Valentin, Christian; Ribolzi, Olivier; de Rouw, Anneke; Thiebaux, Jean-Pierre. 2007. Enhancing water quality through better land management of degraded upland regions in northern Laos. In Gebbie, L.; Glendinning, A.; Lefroy-Braun, R.; Victor, M. (Eds.). Proceedings of the International Conference on Sustainable Sloping Lands and Watershed Management: Linking Research to Strengthen upland Policies and Practices, National Agriculture and Forestry Research Institute of Lao PDR (NAFRI), Vientiane, Lao PDR, 2007. Vientiane, LAO PDR: National Agriculture and Forestry Research Institute of Lao PDR (NAFRI) pp.47-58.
(Location: IWMI HQ Call no: IWMI 333.91 708 SEN Record No: H041510)
3 Vigiak, Olga; Ribolzi, Olivier; Valentin, Christian; Sengtaheuanghoung, O. 2007. Hillslope sediment trapping by natural or cultivated riparian vegetation in northern Laos. In Gebbie, L.; Glendinning, A.; Lefroy-Braun, R.; Victor, M. (Eds.). Proceedings of the International Conference on Sustainable Sloping Lands and Watershed Management: Linking Research to Strengthen upland Policies and Practices, National Agriculture and Forestry Research Institute of Lao PDR (NAFRI), Vientiane, Lao PDR, 2007. Vientiane, LAO PDR: National Agriculture and Forestry Research Institute of Lao PDR (NAFRI) pp.121-129.
(Location: IWMI HQ Call no: IWMI 333.91 708 VIG Record No: H041511)
4 de Rouw, Anneke; Douillet, M.; Tjiantahosong, H.; Ribolzi, Olivier; Thiebaux, Jean-Pierre. 2007. Dispersal of weed seeds by erosion and flow processes in upland fields. In Gebbie, L.; Glendinning, A.; Lefroy-Braun, R.; Victor, M. (Eds.). Proceedings of the International Conference on Sustainable Sloping Lands and Watershed Management: Linking Research to Strengthen upland Policies and Practices, National Agriculture and Forestry Research Institute of Lao PDR (NAFRI), Vientiane, Lao PDR, 2007. Vientiane, LAO PDR: National Agriculture and Forestry Research Institute of Lao PDR (NAFRI) pp.156-166.
(Location: IWMI HQ Call no: IWMI 333.91 708 ROW Record No: H041519)
(Location: IWMI HQ Call no: e-copy only Record No: H041771)
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Groundwater is a vital resource for rural populations in tropical areas who depend on seasonal rainfall. Groundwater is often the only source of water feeding streams, allowing them to flow throughout the dry season. The aim of this study was to evaluate two models for estimating the average duration that soil is waterlogged by shallow groundwater table. These models, based on variations in soil colour, were developed by Blavet et al (2000) from observations and measurements made in a semi-arid environment in West Africa. Therefore there is a need to evaluate whether these models are also pertinent in a mountainous context of northern Laos. Our approach consisted in comparing data obtained from field measurements (water table level, morpho-pedological features including soil colour) with predictions made by the models. This study was carried out along two transects with contrasting characteristics in terms of the landscape morphology as well as the soil hydrodynamic: the first was in an open swampy valley with convex hillslopes, the second was in a steep-banked and narrow valley with convexo-concave hillslopes. Preliminary results from our study identified relationships between soil colour and the mean rate of soil waterlogging and are a first step for developing an inexpensive and simple method to predict soil saturation in this environment.
(Location: IWMI HQ Call no: e-copy only Record No: H041772)
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(Location: IWMI HQ Call no: e-copy only Record No: H041781)
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(Location: IWMI HQ Call no: e-copy only Record No: H041947)
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(Location: IWMI HQ Call no: e-copy only Record No: H041778)
(0.61 MB)
10 Valentin, Christian; Lestrelin, Guillaume; Chanthavongsa, A.; Phachomphon, K.; de Rouw, Anneke; Chanhphengxay, A.; Chaplot, V.; Bourdon, Emmanuel; Briquet, J. P.; Marchand, P.; Pierret, Alain; Ribolzi, Olivier; Thiebaux, Jean-Pierre. 2008. The MSEC project in the Lao PDR at a glance: biophysical and socio-economic background and project experimental set up. Lao Journal of Agriculture and Forestry, Special issue no.17:32-50.
(Location: IWMI HQ Call no: e-copy only Record No: H041777)
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11 Ribolzi, Olivier; Thiebaux, Jean-Pierre; Bourdon, Emmanuel; Briquet, J. P.; Chaplot, V.; Huon, S.; Marchand, P.; Mouche, E.; Pierret, Alain; Robain, H.; de Rouw, Anneke; Sengtahevanghoung, O.; Soulileuth, B.; Valentin, Christian. 2008. Effect of fallow regrowth on stream water yield in a headwater catchment under shifting cultivation in northern Lao PDR. Lao Journal of Agriculture and Forestry, Special issue no.17:52-71.
(Location: IWMI HQ Call no: e-copy only Record No: H041774)
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(Location: IWMI HQ Call no: e-copy only Record No: H041776)
(0.98 MB)
(Location: IWMI HQ Call no: e-copy only Record No: H041775)
(0.78 MB)
14 Rajot, J. L.; Karambiri, H.; Ribolzi, Olivier; Planchon, O.; Thiebaux, Jean-Pierre. 2009. Interaction entre erosions hydrique et eolienne sur sols sableux patures au Sahel: cas du bassin-versant de Katchari au nord du Burkina Faso. In French. [Wind and water erosions of pastured sandy soils in the Sahel: a case study in northern Burkina Faso]. Secheresse, 20(1):131-138.
(Location: IWMI HQ Call no: e-copy only Record No: H042653)
(0.24 MB)
In the Sahel, sandy soils are widespread and support not only most of the pearl millet production, the major staple crop in the region, but also grass production for livestock. Parent sediments of these soils have an aeolian origin and are hence prone to wind erosion. Still, their clay content, even though very low, allows physical crust formation during rainfall leading to runoff and water erosion. Squall lines, major rainfall events of the rainy season, are usually preceded by intense wind. Wind and water erosions are therefore closely associated in both time and space, but they are rarely studied simultaneously. Erosion measurements were performed for two years (2001, 2002) on a small catchment of grazing land (1,4 ha) at Katchari, Burkina Faso, a location typical of the Sahel area with under 500 mm annual rainfall. Wind erosion occurs at the onset of the rainy season, from May to 15th of July, when soil cover is the lowest and before the growth of vegetation. On this non-cultivated area, the same dynamic unfolds as that recorded in millet fields in other sahelian studies. Water erosion occurs throughout the rainy season, but certain intense events produce most of the total annual erosion. Wind causes the largest sediment fluxes leading to both erosion (up to 20 Mg/ha per year) and deposition (up to 30 Mg/ha per year) depending on the area in the catchment. Water erosion is one order of magnitude lower than wind erosion and is more intense where wind erosion is highest. Hence, the same area is eroded by both wind and water. Conversely, areas where aeolian deposition occurs are less affected by water erosion and correspond to fertile islands where vegetation grows. From this study, it comes out that there is on the whole no land degradation at the catchment scale, but an intense aeolian and water dynamic leading to substantial spatial variability typical of sahelian landscapes.
15 Rajot, J.L.; Ribolzi, Olivier; Planchon, O.; Karambiri, H. 2005. Wind and water erosion of non cultivated sandy soils in the Sahel: a case study in northern Burkina Faso, Africa. In International Union of Soil Sciences (IUSS); Institut de Recherche pour le Developpement (IRD); Thailand. Land Development Department (LDD); International Water Management Institute (IWMI); FAO. Regional Office for Asia and the Pacific (FAO RAP); Khon Kaen University. Faculty of Agriculture. Management of tropical sandy soils for sustainable agriculture: a holistic approach for sustainable development of problem soils in the tropics. Proceedings of the First Symposium on Management of Tropical Sandy Soils for Sustainable Ariculture, Khon Kaen, Thailand, 27 November – 2 December 2005. Bangkok, Thailand: FAO Regional Office for Asia and the Pacific (FAO RAP). pp.175-181.
(Location: IWMI HQ Call no: 630 G000 INT Record No: H047326)
(0.60 MB) (16.9 MB)
In the Sahel, sandy soils are widespread and support not only most of pearl millet production, the major staple crop in the region, but also forage production for livestock. Parent sediments of these soils have an aeolian origin and hence are prone to wind erosion. However, the clay content, albeit very low, results in the formation of crusts during rainfall, thus leading to runoff and water erosion. Squall lines, major rainfall events of the rainy season, are usually preceded by intense wind. Wind and water erosion is thus closely associated both in time and in space, but they are rarely studied simultaneously. Erosion measurements were carried out during two years (2001, 2002) on a small catchment of grazing land (1.4 ha) at Katchari, Burkina Faso, typical of the Sahel area under 500 mm annual rainfall. Wind erosion occurred at the onset of the rainy season, when soil cover is the lowest, from May to 15th of July, before vegetation growth. Water erosion occurred throughout the rainy season, but some intense events produced most of the total annual erosion. Wind caused the largest sediment fluxes leading to both erosion (up to 20 Mg ha-1 yr-1) and deposits (up to 30 Mg ha-1 yr-1) according to the area of the catchment. Water erosion is one order of magnitude lower than wind erosion, and is more intense where wind erosion is the highest. Thus the same area is eroded both by wind and water. Conversely, in areas where there are aeolian deposits, water erosion is low and these areas correspond to fertile islands where vegetation grows. At this study scale, there is no land degradation, but intense dynamics leading to a high spatial variability typical of the Sahelian environment. On this uncultivated area, the dynamics were similar to those recorded in other Sahelian cultivated millet fields.
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