From S E Research To Modeling Impacts

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From Soil Erosion Research to Modeling Impacts of Interventions: The Case of Ethiopia By Gete Zeleke GMP UN expert group meeting on “Sustainable land management and agricultural practices in Africa: Bridging the gap between research and farmers” April 16 – 17, 2009, University of Gothenburg, Sweden.
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Transcript of From S E Research To Modeling Impacts

  • 1.From Soil Erosion Research to Modeling Impacts of Interventions: The Case of EthiopiaByGete Zeleke GMP UN expert group meeting on Sustainable land management and agricultural practices in Africa: Bridging the gap between research and farmers April 16 17, 2009, University of Gothenburg, Sweden.

2.

  • Part I: Overview of Land Degradation

3.

  • Huge gulley erosion - This process is still common in most parts of Ethiopia (mainly in potential areas)

4.

  • Precious top soil that used to support life of different forms is washed out of the landscape and land is abandonedfor any meaningful agricultural activity

5. Gete, 2005 Common in the rainy season 6. 7. 8. Land Cover in Dembecha Area, Ethiopia, in 1957and 1995 Gete Zeleke 2000 9. Biological degradation : The invisiblethreat

  • All soils in the country (except pastoralist areas) suffer from soil nutrient mining: Open nutrient cycle!
    • Use of cow dung and crop residue as a source of energy in the country is equivalent to700,000 tonsof grain/year
    • Deteriorates chemical and physical properties of the soil
      • OM content
      • Soil moisture holding capacity
      • Infiltration capacity
      • Soil structure

10.

  • Part II: Some of the major causes

11. 1. Poor Land Management 12.

  • Free grazing
    • Deteriorates soil physical properties
    • Destroy soil conservation measures
    • Remove crop residue from the soil
    • Detach soil particles
  • Unbalanced carrying capacity resulted in overgrazing

2. Poor Livestock Management 13. 3. Energy sources for HH domestic use Amare, 2008 14.

  • 4. High Population Pressure: it is contextual
    • Limited capacity and access
    • High level of illiteracy weak awareness
    • Dependant on subsistent farming 85%
    • Push people to marginal areas

Slide from Zelalem, 2006 Hurni, 2007 15. 5. Lack of proper awareness on extent and impacts of LD & other EPs

  • Very poor resource database and utilization
    • Eg. Soil database
  • Lack of or incomplete empirical evidences on extent and impacts of LD and other EPs
  • Poor way of communication e.g..tones of soil/ha/y, ha of forest/y, % siltation, climate change...etc*******
  • No cost benefit analysis

16.

  • Part III: Experiences on SLM

17. 18. (4) Water tables and water supply (5) Biomass for livestock and bee keeping 19. 20. 21. February 2004 October 2005 19 May 2003 October 2005 22.

  • Part IV: Mechanisms of capturing process to influence agricultural development positively

23. What is need to make informed decisions on Agri. deve?

    • Need to have resource database (at least soil, water, climate and genetic resources)
    • Need to know rate and magnitude of soil erosion/runoff under different AEZ, soil types, land use systems, etc
    • Need to know what technology works, where, and under what condition
    • Need to know negative impacts of Soil erosion (land degradation) and positive impacts of applying improved land management practices

24. What are Possible approaches?

  • Approach 1:
  • Measuring soil erosion in all watersheds
  • Measuring effects of all land management practices in different parts (too expensive)
  • Approach 2:
  • Measure selective and representative watersheds
  • Measure selective and right combinations of LM practices(Achievable)
  • Approach 3:
  • Extrapolate the result to ungauged areas using a combination of GIS, biophysical and economic models
          • (Achievable)

25. Framework for Assessing Major LD Processes & Impacts (Approach 2) LD On-site Off-site Types of Impacts

  • Siltation/sedimentation
  • Reservoirs/dams
  • Lakes
  • On farm lands
  • Soil loss due to Sheet & rill erosion by water
  • Loss of soil nutrients through DB, CRB & GR

Processes captured

  • water supply
  • irrigation water supply
  • Power generation
  • Biodiversity
  • Destruction of productive lands
  • Productionloss

Impacts quantified 26. What do we have on this? LD On-site Off-site

  • water supply
  • irrigation water supply
  • Power generation
  • Biodiversity
  • Destruction of productive lands

Very little We know SCRP & others

  • Productionloss
  • Siltation/sedimentation
  • Reservoirs/dams
  • Lakes
  • On farm lands
  • Soil loss due to Sheet & rill erosion by water
  • Loss of soil nutrients through DB, CRB & GR

Types of Impacts Processes captured Impacts quantified 27. Afdeyu 28.

  • Two key processes to be captured:
  • Watershed status (hill slope Processes
  • Stream gauging

29. Database from SCRP

  • Watershed level
    • Catchment runoff - hydrographs
    • Sediment yield
    • Climate
    • Land use
    • Harvest
    • Soil depth
    • Socio-economic data
  • Plot level
    • Soil loss
    • Runoff
    • Yield
    • SWC measures impact/land use/design/type

With and without scenario 30. Framework for Assessing Impacts of LM Practices (Approach 2 cont..) LM On-site Off-site Types of Impacts

  • Effect in reducing Siltation/sedimentation
  • Reservoirs/dams
  • Lakes
  • On farm lands
  • Effectiveness in reducing soil loss
  • Effect in improving soil fertility and depth
  • Effect on moisture conservation and soil water holding capacity

Processes captured

  • water supply
  • irrigation water supply
  • Power generation
  • Biodiversity
  • Protection of productive lands
  • Productiongains

Impacts quantified 31. What do we have? LM On-site Off-site

  • water supply
  • irrigation water supply
  • Power generation
  • Biodiversity
  • Protection of productive lands

No measured data We have some data (SCRP/HLI/EIAR but need to be organized)

  • Productiongains
  • Effect in reducing Siltation/sedimentation
  • Reservoirs/dams
  • Lakes
  • On farm lands
  • Effectiveness in reducing soil loss
  • Effect in improving soil fertility and depth
  • Effect on moisture conservation and soil water holding capacity

Types of Impacts Processes captured Impacts quantified 32. What is missing or less addressed?

  • Offsite processes and impacts of LD
  • Info on impacts of LM practices (only few)
  • Info on impacts of integrated land management practices
  • Socio-economic aspects of SLM and LD (need more work)

33. Approach 3: Methods of extrapolation

  • Selection of appropriate models and tools
    • Modeling
      • Model
        • Choice of appropriate model
          • USLE On-site processes (soil loss)
          • SWAT- Off-site process (siltation)
      • Gauged values to calibrate and validate model
          • SCRP watersheds
    • GIS
      • To identify recommendation domains

34. Methods of extrapolation cont

  • Steps to be followed
  • Characterize each station
    • Biophysical parameters
    • Socio-economic parameters
  • Reclassify country coverages of bio-physical and SE parameters
  • Identify recommendation domains
  • Test model on station
  • Calibrate and validate model using gauged station data
  • Apply model on recommendation domains

35. Processes of Identifying Recommendation Domains using GIS Environment (soil loss, Nutrient loss & SLM)

  • - Altitude
  • - Rainfall
  • - LGP
  • - Slope
  • - Soil
  • Farming system
  • Land Use etc

Reclassify country coverage and develop layers for each parameter Recommend. Domains Develop Ranges of parameters Overlay (model) GIS Modelling 36. Examples of National coverage for key parameters 37. farming system Farming system: Ethiopia 38. extrapolation of station data based on similarity of environmental conditions 39. farming system Farming system: teff, wheat, maize & pulses Farming system Similar to Anjeni 40. soils Soils Similar to Anjeni 41. altitude Altitudinal belts Similar to Anjeni 42. rainfall Annual rainfall Similar to Anjeni 43. LGP Similar to Anjeni 44. slope Slope Similar to Anjeni 45. temperature Annual Meant Temp Similar to Anjeni 46. GIS Modelling and Overlays: Areas that can be represented by Anjeni 47. Areas that can be represented by Anjeni- by woreda (range) 48. Areas that can be represented by Anjeni- by woreda ( best fit areas only ) 49. Part V: ExtrapolationA: Model application (Eg. USLE) to extrapolateon-siteprocesses and impacts 50. LD On-site SLM

  • Productionloss
  • Soil loss due to Sheet & rill erosion by water
  • Loss of soil nutrients through DB, CRB & GR

Types of Impacts Processes captured Impacts quantified

  • Effectiveness in reducing soil loss
  • Effect in improving soil fertility and depth
  • Effect on moisture conservation and soil water holding capacity
  • Productiongains

51. Phase I: Model validation at station level

  • 1. Quantifying Soil Loss:
  • Parameter generation
    • R, K, S, L, C, P
  • Model calibration
  • Parameter adjustment including methods of generation
  • Validate model
  • Recommend options for:
    • Model response and interpretation requirements
    • procedures parameter generation
    • Options including tables, equations

52. Parameter generation options

  • Eg. K factor
  • 1.
  • 2.
  • 3.
  • 4. Or use table developed based on Ethiopian experience

53. 2. Quantifying Nutrient Loss

  • We chooseonlythree important ways of nutrient loss from the soil
    • Burning of dung
    • Burning of crop residue
    • Removal of grain
  • We consider three possibilities of nutrient addition to the soil
    • Fixation
    • Weathering
    • Artificial fertilizer or manuring
  • Weonlyaddress two nutrients
    • N
    • P
  • Remark:the method can be used to include others

54. Procedures

  • Determine nutrient content of dung, crop residue and major crops
  • Set conversion coefficient - % of energy consumption covered by dung and crop residue per person, per year
  • Convert this to dung and CR used
  • Convert this to N & P loss from dung and CR

55. Procedures cont

  • Estimate production of major crops for each zone and
  • Convert this into N & P loss
  • Calculate Nutrient addition by different means
  • Calculate net nutrient loss:

56. 3. Quantifying impacts of SLM practices

  • 1. Scenario 1. Only Physical SWC measures
    • Use SCRP values
    • Adjust P factor
  • 2. Scenario 2. Physical SWC with SF/SMM
    • Extrapolate from existing values or measure
    • Adjust P factor and may be C factor
  • 3. Scenario 3. All best LMP
    • Extrapolate of measure
    • Adjust P factor and C factor
  • 4. Area closure and forestry
    • Extrapolate or measure
    • adjust P factor and C factor

57. Phase II: Procedures of extrapolation to Recommendation Domains (Eg) Soil Loss (Map and Data) K- Map LS - Map C/P - Map R MapSoil Map DEM Land Use Map Climate Overlay 58. B: Model application (Eg. SWAT) to extrapolateoff-siteprocesses and impacts 59. Off-site

  • water supply
  • irrigation water supply
  • Power generation
  • Biodiversity loss
  • Destruction of productive lands
  • Improved:
  • water supply
  • irrigation water supply
  • Power generation
  • Biodiversity
  • Protection of productive lands

LD SLM

  • Siltation/sedimentation
  • Reservoirs/dams
  • Lakes
  • On farm lands

Types of Impacts Processes captured Impacts quantified

  • Effect in reducing Siltation/sedimentation
  • Reservoirs/dams
  • Lakes
  • On farm lands

60. 1. Quantifying siltation using SWAT

  • SWAT is a dynamic watershed/basin model
  • Developed by USDA-ARS
  • It simulates:
    • Crop growth
    • Hydrology
    • Soil erosion
    • Climate
    • Updates model parameters on a daily basis
    • It takes point sources as input
    • Impacts of land management practices
    • Point and non point pollutant
  • Output:
    • Sediment yield
    • Runoff
    • Nutrient and pollutant balance
    • Etc

61. 1. Quantifying siltation using SWAT cont.

  • SWAT simulates at three levels
    • HRU
      • Homogenous units in terms of soil and land use
    • Sub-basin (smaller watershed)
      • Holds a number of HRU
    • Basin (bigger watershed)
      • Holds a number of sub-basins
  • Has GIS interface and the model can run through GIS
  • Has weather generator

62. HRUs Basin/Big watershed ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( ! ( drainage outlets drainage lines microbasins Sub- basin/sub-watershed 63. Procedures of using SAWT

  • Validate model using SCRP station data
    • Generate parameter
    • Conduct sensitivity analysis
    • Calibrate model
    • Adjust model parameters
    • Validate model
  • Apply model on selected basins
    • Prepare soil map and data
    • Prepare and use map and data
    • Prepare DEM
    • Map climate variables
    • Indicate point sources
    • Produce parameter built model database
    • Run the model

64. 65.

  • Build required resource database
  • Develop information on SLM scenarios
    • Develop generic values based on some observation
    • If absolutely needed establish learning sites
  • Build capacity
    • On modelling
    • Parameterization
  • Develop packages of recommendation
  • Develop feedback system among research, extension and policy makers

Conclusion