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B1. Quantifying the role of AF in modifying watershed functions Starting from current practice in 'integrated watershed management' with participatory.

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Presentation on theme: "B1. Quantifying the role of AF in modifying watershed functions Starting from current practice in 'integrated watershed management' with participatory."— Presentation transcript:

1 B1. Quantifying the role of AF in modifying watershed functions Starting from current practice in 'integrated watershed management' with participatory methods Biophysical Gains of Participatory Agroforestry: Evidence from Integrated Watershed Development Project, Hills II, India Collective action in integrated soil and water conservation: the case of Gununo Watershed, Southern Ethiopia Delving deeper into the biophysical processes CONVERSION OF FOREST TO COFFEE-BASED AGROFORESTRY IN INDONESIA: Litter layer, residence time, population density of earthworm and Modelling water dynamics in coffee systems - Parameterization of a mechanistic model over two production cycles in Costa Rica. Impacts of shade trees on hydrological services and erosion in a coffee AFS of Costa Rica: Scaling from plot to watershed Tree roots anchoring soil and reducing landslide risk during high rainfall episodes as basis for adaptation and mitigation to climate change Scaling back up to the landscape Buffering water flows through agroforestry management: quantifying the influence of landscape mosaic composition and pattern

2 Buffering water flows through agroforestry management: quantifying the influence of landscape mosaic composition and pattern Meine van Noordwijk, Betha Lusiana, Bruno Verbist

3 Sustainable land use Agroforestry Hydrological Functions Watershed management ‘Protec -tive garden’ Trees, Soil, Drainage Stakehol- der nego- tiation Criteria & Indicators Buffering water flows through agroforestry management: quanti- fying the influence of landscape mosaic composition and pattern

4 rainfall lateral outflow percolation surface evaporation transpiration canopy water evaporation uptake quick- flow base flow { surface run-on sub- surface lateral inflow surface run-off Stream: stem-flow through-fall cloud interception recharge infiltration

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6 Is Q max /Q min a suitable indicator? Maximum flow (Q max ) reflects the biggest rainfall event (minus infiltration) Minimum flow (Q min ) reflects the longest dry period (as long as groundwater was fully recharged at end of rains) The ratio of these two reflects climate variability – with potentially some impacts of landscape quality We need real indicator of watershed condition, independent of weather

7 Basic Watershed Components Base Flow Ground water Sediment Loss Rainfall Overland Flow River Transpiration Sub-surface flow Water Input Lateral Flows, Filters, Channels, & Storage “pump” “sponge” Water Outputs

8 Buffering of flows at multiple scales Contributing factors Interception + canopy drip => half hour shift Surface flow vs infiltration => 1-2 day shift Flow conditions in river bed => few hours Impoundments, wetland overflow areas => days Spatial variability of rainfall => weeks Lakes and man-made reservoirs => months, rarely years

9 Precipitation = P Evapotranspiration = E River flow = Q Q quick Q slow E veg E soil E interc E irr infiltration interception E soil + E veg E interc Q slow Q quick Energy- limited E potential Signal modification along river precipitation 1. Transmit water 2. Buffer peak rain events 3. Release gradually 4. Maintain quality 5. Reduce mass wasting Q/P=1-(E/P)  Q abAvg /  P abAvg Q slow /P = (P inf – E S+V )/P Qual out /Qual in  risk Scale dependent

10 Point of inflection when landscape sponge reaches saturation A. Cumulative rainfall, mm Small effects of land use change relative to interannual variability Cumulative dry season flow = drying out the sponge Source: Xing Ma, Jianchu Xu & Meine van Noordwijk : Sensitivity of streamflow from a Himalayan catchment to plausible changes in land-cover and climate (submitted)

11 Wettest month in Mae Chaem is approaching Way Besai 1 – slope of line = buffering indicator

12 Source: Xing Ma, Jianchu Xu & Meine van Noordwijk : Sensitivity of streamflow from a Himalayan catchment to plausible changes in land-cover and climate (submitted)

13 River today River yesterday Flow persistence 0.75 Way Besay, Sumberjaya

14 Interpreting flow persistence on basis of flow pathways: Flow persistence of overland flow ~ 0.0,, interflow (soil quick flow) ~ 0.5,, groundwater flow ~ 0.95

15 Conclusions Three quantitative indicators are now available for further testing: 1)Flow persistence – day-to-day predictability of riverflow; 1 = perfectly bufferred, 0 = no buffering at all; index can be decomposed into flow path contributions 2)Buffer indicator as above-average discharge per unit above-average rainfall: seasonal or yearly indicator 3)CumRain versus CumRiverflow transition points for sponge saturation effects and timing of buffer saturation


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