Your search found 14 records
1 Greenland, D. J.; Bowen, G.; Eswaran, H.; Rhoades, R.; Valentin, C.. 1994. Soil, water and nutrient management research: A new agenda. viii, 71p.
Soil management ; Water management ; Nutrition ; Research ; Natural resources ; Environmental sustainability
(Location: IWMI-SA Call no: 631.4 G000 GRE Record No: H014263)
A position paper prepared under the auspices of ACIAR; French Ministry of Foreign Affairs; ODA; Swiss Development Cooperation; USAID, at The International Board for Soil Research and Management, Bangkok.
2 Cook, S.; Johnson, N.; Swallow, B.; Ravnburg, H.; Beaulieu, N.; Mulligan, M.; Schreier, H.; Valentin, C.; Wani, S. P.; Penning de Vries, F.; Sanz, N.; Gottriet, V.; Westermann, O. 2002. Multiple use of upper catchments: toward a research agenda for Subtheme Two of the Challenge Program on water and food. Challenge Program on Water and Food background paper 2. In CGIAR Challenge Program on Water and Food. Challenge Program on Water and Food: background papers to the full proposal. Colombo, Sri Lanka: CGIAR Challenge Program on Water and Food. pp.43-84.
Catchment areas ; Watershed management ; Agricultural research ; Research projects ; Poverty ; indicators ; Living conditions ; Water use ; Water quality ; Hydrology ; Water balance ; Conflict
(Location: IWMI HQ Call no: 333.91 G000 CGI Record No: H031288)
3 Janeau, J. L.; Bricquet, J. P.; Planchon, O.; Valentin, C.. 2003. Soil crusting and infiltration on steep slopes in northern Thailand. European Journal of Soil Science, 54:543-553.
(Location: IWMI-HQ Call no: 631.4 G750 JAN Record No: H032937)
4 Maglinao, A. R.; Valentin, C.. 2003. Catchment approach to managing soil erosion in Asia. In Harwood, R. R.; Kassam, A. H. (Eds.), Research towards integrated natural resources management: Examples of research problems, approaches and partnerships in action in the CGIAR. Rome, Italy: FAO. pp.21-46.
Erosion ; Catchment areas ; Land management ; Runoff ; Sedimentation ; Land use ; Tillage / Asia / Indonesia / Laos / Nepal / Philippines / Thailand / Vietnam
(Location: IWMI-HQ Call no: 333.7 GG000 HAR Record No: H034319)
5 Podwojewski, P.; Orange, Didier; Jouquet, Pascal; Valentin, C.; Nguyen, V. T.; Janeau, J. L.; Toan, T. D. 2008. Land-use impacts on surface runoff and soil detachment within agricultural sloping lands in northern Vietnam. Catena, 74:109-118.
Surface runoff ; Land use ; Sloping land ; Cassava ; Eucalyptus ; Fodder ; Environmental degradation ; Catchment areas ; Soil properties ; Vegetation / Vietnam
(Location: IWMI HQ Call no: IWMI 631.4 G784 POD Record No: H041496)
6 Penning de Vries, F.; Acquay, H.; Molden, David; Scherr, S.; Valentin, C.; Cofie, Olufunke. 2008. Learning from bright spots to enhance food security and to combat degradation of water and land resources. In Bossio, Deborah; Geheb, Kim (Eds.). Conserving land, protecting water. Wallingford, UK: CABI; Colombo, Sri Lanka: International Water Management Institute (IWMI); Colombo, Sri Lanka: CGIAR Challenge Program on Water & Food. pp.1-19. (Comprehensive Assessment of Water Management in Agriculture Series 6)
(Location: IWMI HQ Call no: IWMI 631.7 G000 BOS Record No: H041590)
7 Pierret, A.; de Rouw, A.; Chaplot, V.; Valentin, C.; Noble, Andrew; Suhardiman, Diana; Drechsel, Pay. 2011. Reshaping upland farming policies to support nature and livelihoods: lessons from soil erosion in Southeast Asia with emphasis on Lao PDR. [Report of the Management of Soil Erosion Consortium (MSEC) Project]. Marseille, France: Institut de Recherche pour le Developpment (IRD); Colombo, Sri Lanka: International Water Management Institute (IWMI). 40p. [doi: https://doi.org/10.5337/2011.213]
Upland areas ; Farming systems ; Shifting cultivation ; Agricultural policy ; Erosion ; Soil conservation ; Tillage ; Land use ; Site ; Monitoring ; Catchment areas ; Surface runoff ; Riparian zones ; Water management ; Vegetation ; Rain / Southeast Asia / Laos
(Location: IWMI HQ Call no: IWMI Record No: H044693)
(3.98 MB)
8 Mouche, E.; Moussu, F.; Mugler, C.; Ribolzi, O.; Valentin, C.; Sengtahevanghoung, O.; Lacombe, Guillaume. 2014. Impact of land-use change on the hydrology of North Lao PDR watersheds. In Daniell, T. M.; Van Lanen, H. A. J.; Demuth, S.; Laaha, G.; Servat, E.; Gil Mahe, J.-F. B.; Paturel, J.-E.; Dezetter, A.; Ruelland, D. (Eds.). Hydrology in a changing world : environmental and human dimensions: proceedings of the FRIEND [Flow Regime from International Experimental and Network Data] Water Conference, Montpellier, France, 7-10 October 2014. Wallingford, UK: International Association of Hydrological Sciences (IAHS). pp.84-89. (IAHS Publication 363)
Land use ; Hydrology ; Watersheds ; Impact assessment ; Agriculture ; Catchment areas ; Rain ; Runoff ; River basins / Lao People's Democratic Republic / Mekong River / Nam Khan Watershed / Nam Ou Watershed / Nam Suong Watershed / Nam Lik Watershed / Nam Ngum Watershed / Houay Pano Catchment
(Location: IWMI HQ Call no: e-copy only Record No: H046864)
(0.42 MB)
We investigated the impact of land-use change on the hydrology of different major Lao tributary watersheds of Mekong River. The region is the North of Laos centred on Luang Prabang and the watersheds are the Nam Khan, Nam Ou, Nam Suong, Nam Lik and Nam Ngum. An additional small agricultural catchment called Houay Pano close to the Nam Khan, is also considered. We used the lumped rainfall–runoff conceptual models GR4J and GR2M, developed by Irstea in France, the Mekong River Commission hydro-meteorological database and the Japanese Aphrodite meteorological database. The objective was to detect in the hydrological regime of the watersheds an impact of de(re)forestation, processes known to have occurred since the 1980s, but at a degree which has not been quantified. For this purpose we adopted the cross simulation methodology developed by Irstea which has proved to be efficient to detect trends in long term watershed hydrology. The results did not show any significant hydrological change since 1960. On the other hand the application of the same methodology to the small catchment Houay Pano surveyed since 2001 proved to be convincing. We saw evidence of the impact of slash and burn practice, followed by a long fallow period, on a catchment’s hydrology over a seven year period.
9 Lacombe, Guillaume; Ribolzi, O.; de Rouw, A.; Pierret, A.; Latsachak, K.; Silvera, N.; Pham Dinh, R.; Orange, D.; Janeau, J.-L.; Soulileuth, B.; Robain, H.; Taccoen, A.; Sengphaathith, P.; Mouche, E.; Sengtaheuanghoung, O.; Tran Duc, T.; Valentin, C.. 2015. Afforestation by natural regeneration or by tree planting: examples of opposite hydrological impacts evidenced by long-term field monitoring in the humid tropics. Hydrology and Earth System Sciences Discussions, 12:12615-12648. [doi: https://doi.org/10.5194/hessd-12-12615-2015]
Afforestation ; Plantations ; Tectona grandis ; Hydrological factors ; Humid tropics ; Ecosystem services ; Land use ; Soil conservation ; Water conservation ; Catchment areas ; Rain ; Runoff ; Models / Lao People s Democratic Republic / Vietnam / Houay Pano Catchment / Dong Cao Catchment
(Location: IWMI HQ Call no: e-copy only Record No: H047340)
http://www.hydrol-earth-syst-sci-discuss.net/12/12615/2015/hessd-12-12615-2015.pdf
https://vlibrary.iwmi.org/pdf/H047340.pdf
https://vlibrary.iwmi.org/pdf/H047340.pdf
(3.39 MB) (3.39 MB)
The humid tropics are exposed to an unprecedented modernization of agriculture involving rapid and highly-mixed land-use changes with contrasted environmental impacts. Afforestation is often mentioned as an unambiguous solution for restoring ecosystem services and enhancing biodiversity. One consequence of afforestation is the alteration of streamflow variability controlling habitats, water resources and flood risks. We demonstrate that afforestation by tree planting or by natural forest regeneration can induce opposite hydrological changes. An observatory including long-term field measurements of fine-scale land-use mosaics and of hydro-meteorological variables has been operating in several headwater catchments in tropical Southeast Asia since 2001. The GR2M water balance model repeatedly calibrated over successive 1 year periods, and used in simulation mode with specific rainfall input, allowed the hydrological effect of land-use change to be isolated from that of rainfall variability in two of these catchments in Laos and Vietnam. Visual inspection of hydrographs, correlation analyses and trend detection tests allowed causality between land-use changes and changes in seasonal flows to be ascertained. In Laos, the combination of shifting cultivation system (alternation of rice and fallow) and the gradual increase of teak tree plantations replacing fallow, led to intricate flow patterns: pluri-annual flow cycles induced by the shifting system, on top of a gradual flow increase over years caused by the spread of the plantation. In Vietnam, the abandonment of continuously cropped areas mixed with patches of tree plantations led to the natural re-growth of forest communities followed by a gradual drop in streamflow. Soil infiltrability controlled by surface crusting is the predominant process explaining why two modes of afforestation (natural regeneration or planting) led to opposite changes in flow regime. Given that commercial tree plantations will continue to expand in the humid tropics, careful consideration is needed before attributing to them positive effects on water and soil conservation.
10 Lacombe, Guillaume; Ribolzi, O.; de Rouw, A.; Pierret, A.; Latsachak, K.; Silvera, N.; Dinh, R. P.; Orange, D.; Janeau, J.-L.; Soulileuth, B.; Robain, H.; Taccoen, A.; Sengphaathith, P.; Mouche, E.; Sengtaheuanghoung, O.; Tran Duc, T.; Valentin, C.. 2016. Contradictory hydrological impacts of afforestation in the humid tropics evidenced by long-term field monitoring and simulation modelling. Hydrology and Earth System Sciences, 20:2691-2704.
Humid tropics ; Hydrological factors ; Afforestation ; Natural regeneration ; Plantations ; Monitoring ; Simulation models ; Land use ; Land cover change ; Ecosystem services ; Forest conservation ; Catchment areas ; Rainfall-runoff relationships ; Stream flow ; Cropping systems ; Water conservation ; Soil conservation ; Soil surface properties ; Tectona grandis / Lao People's Democratic Republic / Vietnam / Houay Pano Catchment / Dong Cao Catchment
(Location: IWMI HQ Call no: e-copy only Record No: H047644)
http://www.hydrol-earth-syst-sci.net/20/2691/2016/hess-20-2691-2016.pdf
https://vlibrary.iwmi.org/pdf/H047644.pdf
https://vlibrary.iwmi.org/pdf/H047644.pdf
The humid tropics are exposed to an unprecedented modernisation of agriculture involving rapid and mixed land-use changes with contrasted environmental impacts. Afforestation is often mentioned as an unambiguous solution for restoring ecosystem services and enhancing biodiversity. One consequence of afforestation is the alteration of streamflow variability which controls habitats, water resources, and flood risks. We demonstrate that afforestation by tree planting or by natural forest regeneration can induce opposite hydrological changes. An observatory including long-term field measurements of fine-scale land-use mosaics and of hydrometeorological variables has been operating in several headwater catchments in tropical southeast Asia since 2000. The GR2M water balance model, repeatedly calibrated over successive 1-year periods and used in simulation mode with the same year of rainfall input, allowed the hydrological effect of land-use change to be isolated from that of rainfall variability in two of these catchments in Laos and Vietnam. Visual inspection of hydrographs, correlation analyses, and trend detection tests allowed causality between land-use changes and changes in seasonal streamflow to be ascertained. In Laos, the combination of shifting cultivation system (alternation of rice and fallow) and the gradual increase of teak tree plantations replacing fallow led to intricate streamflow patterns: pluri-annual streamflow cycles induced by the shifting system, on top of a gradual streamflow increase over years caused by the spread of the plantations. In Vietnam, the abandonment of continuously cropped areas combined with patches of mix-trees plantations led to the natural re-growth of forest communities followed by a gradual drop in streamflow. Soil infiltrability controlled by surface crusting is the predominant process explaining why two modes of afforestation (natural regeneration vs. planting) led to opposite changes in streamflow regime. Given that commercial tree plantations will continue to expand in the humid tropics, careful consideration is needed before attributing to them positive effects on water and soil conservation.
11 Ribolzi, O.; Evrard, O.; Huon, S.; de Rouw, A.; Silvera, N.; Latsachack, K. O.; Soulileuth, B.; Lefevre, I.; Pierret, A.; Lacombe, Guillaume; Sengtaheuanghoung, O.; Valentin, C.. 2017. From shifting cultivation to teak plantation: effect on overland flow and sediment yield in a montane tropical catchment. Scientific Reports, 7:1-12. [doi: https://doi.org/10.1038/s41598-017-04385-2]
Teak ; Plantations ; Sediment ; Shifting cultivation ; Overland flow ; Erosion ; Slopes ; Land use ; Land management ; Flow discharge ; Vegetation ; Catchment areas ; Rainfall-runoff relationships ; Infiltration ; Soil sampling / Southeastern Asia
(Location: IWMI HQ Call no: e-copy only Record No: H048176)
(2.73 MB)
Soil erosion supplies large quantities of sediments to rivers of Southeastern Asia. It reduces soil fertility of agro-ecosystems located on hillslopes, and it degrades, downstream, water resource quality and leads to the siltation of reservoirs. An increase in the surface area covered with commercial perennial monocultures such as teak plantations is currently observed at the expanse of traditional slash-andburn cultivation systems in steep montane environments of these regions. The impacts of land-use change on the hydrological response and sediment yields have been investigated in a representative catchment of Laos monitored for 13 years. After the gradual conversion of rice-based shifting cultivation to teak plantation-based systems, overland flow contribution to stream flow increased from 16 to 31% and sediment yield raised from 98 to 609 Mg km-2. This result is explained by the higher kinetic energy of raindrops falling from the canopy, the virtual absence of understorey vegetation cover to dissipate drop energy and the formation of an impermeable surface crust accelerating the formation and concentration of overland flow. The 25-to-50% lower 137Cs activities measured in soils collected under mature teak plantations compared to soils under other land uses illustrate the severity of soil erosion processes occurring in teak plantations.
12 Lacombe, Guillaume; Valentin, C.; Sounyafong, P.; de Rouw, A.; Soulileuth, B.; Silvera, N.; Pierret, A.; Sengtaheuanghoung, O.; Ribolzi, O. 2018. Linking crop structure, throughfall, soil surface conditions, runoff and soil detachment: 10 land uses analyzed in northern Laos. Science of the Total Environment, 616-617:1330-1338. [doi: https://doi.org/10.1016/j.scitotenv.2017.10.185]
Crops ; Soil surface properties ; Erosion ; Runoff ; Sloping land ; Food security ; Plantations ; Vegetation ; Rain ; Infiltration ; Catchment areas ; Land useCrops ; Soil surface properties ; Erosion ; Runoff ; Sloping land ; Food security ; Plantations ; Vegetation ; Rain ; Infiltration ; Catchment areas ; Land use ; Sediment ; Concentrating ; Sediment ; Concentrating / Southeast Asia / Lao People's Democratic Republic
(Location: IWMI HQ Call no: e-copy only Record No: H048341)
In Montane Southeast Asia, deforestation and unsuitable combinations of crops and agricultural practices degrade soils at an unprecedented rate. Typically, smallholder farmers gain income from “available” land by replacing fallow or secondary forest by perennial crops. We aimed to understand how these practices increase or reduce soil erosion. Ten land uses were monitored in Northern Laos during the 2015 monsoon, using local farmers' fields. Experiments included plots of the conventional system (food crops and fallow), and land uses corresponding to new market opportunities (e.g. commercial tree plantations). Land uses were characterized by measuring plant cover and plant mean height per vegetation layer. Recorded meteorological variables included rainfall intensity, throughfall amount, throughfall kinetic energy (TKE), and raindrop size. Runoff coefficient, soil loss, and the percentage areas of soil surface types (free aggregates and gravel; crusts; macro-faunal, vegetal and pedestal features; plant litter) were derived from observations and measurements in 1-m2 micro-plots. Relationships between these variables were explored with multiple regression analyses. Our results indicate that TKE induces soil crusting and soil loss. By reducing rainfall infiltration, crusted area enhances runoff, which removes and transports soil particles detached by splash over non-crusted areas. TKE is lower under land uses reducing the velocity of raindrops and/or preventing an increase in their size. Optimal vegetation structures combine minimum height of the lowest layer (to reduce drop velocity at ground level) and maximum coverage (to intercept the largest amount of rainfall), as exemplified by broom grass (Thysanolaena latifolia). In contrast, high canopies with large leaves will increase TKE by enlarging raindrops, as exemplified by teak trees (Tectona grandis), unless a protective understorey exists under the trees. Policies that ban the burning of multi-layered vegetation structure under tree plantations should be enforced. Shade-tolerant shrubs and grasses with potential economic return could be promoted as understorey.
13 Evrard, O.; Ribolzi, O.; Huon, S.; de Rouw. A.; Silvera, N.; Latsachack, K. O.; Soulileuth, B.; Lefevre, I.; Lacombe, Guillaume; Sengtaheuanghoung, O.; Valentin, C.. 2017. Conversion of traditional cropland into teak plantations strongly increased soil erosion in montane catchments of Southeastern Asia [Abstract only] Paper presented at the American Geophysical Union Fall Meeting (AGU), New Orleans, USA, 11-15 December 2017. 1p.
Erosion ; Sediment ; Land use ; Farmland ; Teak ; Plantations ; Catchment areas ; Stream flow ; Vegetation ; Local communities ; Agroforestry / Southeast Asia / Lao People's Democratic Republic
(Location: IWMI HQ Call no: e-copy only Record No: H048619)
Soil erosion delivers an excessive quantity of sediment to rivers of Southeastern Asia. Land use is rapidly changing in this region of the world, and these modifications may further accelerate soil erosion in this area. Although the conversion of forests into cropland has often been investigated, much fewer studies have addressed the replacement of traditional slash-and-burn cultivation systems with commercial perennial monocultures such as teak plantations. The current research investigated the impact of this land use change on the hydrological response and the sediment yields from a representative catchment of Northern Laos (Houay Pano, 0.6 km²) where longterm monitoring (2002-2014) was conducted (http://msec.obs-mip.fr/). The results showed a significant growth in the overland flow contribution to stream flow (from 16 to 31%). Furthermore, sediment yields strongly increased from 98 to 609 Mg km-2. These changes illustrate the severity of soil erosion processes occurring under teak plantations characterized by the virtual absence of understorey vegetation to dissipate raindrop energy, which facilitates the formation of an impermeable surface crust. This counter-intuitive increase of soil erosion generated by afforestation reflects the difficulty to find sustainable production solutions for the local populations of Southeastern Asia. To reduce soil loss under teak plantations, the development of extensive agro-forestry practices could be promoted.
14 Ribolzi, O.; Lacombe, Guillaume; Pierret, A.; Robain, H.; Sounyafong, P.; de Rouw, A.; Soulileuth, B.; Mouche, E.; Huon, S.; Silvera, N.; Latxachak, K. O.; Sengtaheuanghoung, O.; Valentin, C.. 2018. Interacting land use and soil surface dynamics control groundwater outflow in a montane catchment of the lower Mekong basin. Agriculture, Ecosystems and Environment, 268: 90-102. [doi: https://doi.org/10.1016/j.agee.2018.09.005]
Hydrology ; Land use ; Soil surface properties ; Soil crusts ; Groundwater recharge ; Flow discharge ; Water level ; Water table ; Catchment areas ; Stream flow ; Models ; Evapotranspiration ; Rain ; Runoff ; Infiltration ; River basins / China / Myanmar / Lao People's Democratic Republic / Thailand / Cambodia / Vietnam / Lower Mekong Basin
(Location: IWMI HQ Call no: e-copy only Record No: H048984)
Groundwater contribution to streamflow sustains biodiversity and enhances ecosystem services, especially under monsoon-driven climate where stream baseflow is often the only available water resource during the dry season. We assessed how land use change influences streamflow and its groundwater contribution in a small headwater catchment subject to shifting cultivation in Montane Southeast Asia. Continuous time series of rainfall, reference evapotranspiration, groundwater level, stream discharge and electrical conductivity (EC) of surface and groundwater were monitored from 2002 to 2007. With the rainfall-runoff model GR4J, we investigated temporal changes in the hydrological behaviour of the study catchment to verify consistencies with observed land use change. An EC-based hydrograph separation method allowed estimating the groundwater contribution to 104 stormflow events. Mean soil surface crusting rates corresponding to each of the nine land uses identified in the catchment were determined using 236 standard 1-m2 micro-plots. Mean plant cover for each land use was assessed in 10 × 10-m2 plots. Bedrock topography and soil layers’ structure were assessed by electrical resistivity tomography to determine pathways of subsurface storm flows. Our results indicate that an increase in the catchment's areal percentage of fallow from 33% to 71% led to a decrease in the annual runoff coefficient from 43% to 26%. The concurrent reduction of soil crusting rate over the catchment, from 48% to 30%, increased rainwater infiltration. Consecutively, groundwater contribution to storm streamflow increased from 83% to 94%, highlighting the protective role of a dense vegetation cover against flash floods. The overall reduction of the annual basin water yield for inter-storm streamflow from 450 to 185 mm suggests that the potential gain in groundwater recharge was offset by the increased root water uptake for evapotranspiration, as confirmed by the drop in the groundwater level. This analysis illustrates how two different land uses with opposite impacts on soil permeability (i/ extensive soil surface crusting under annual crops resulting in limited runoff infiltration or ii/ fallow regrowth promoting both infiltration and evapotranspiration) both inhibit groundwater recharge. The maintenance of strips of fallow buffers between annual crop plots can slow down runoff and locally promote infiltration and groundwater recharge while limiting evapotranspiration.
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