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Assessing the Implications of Water Harvesting Intensification on - - PowerPoint PPT Presentation

Aug 30, 2023 258 likes •489 views

Assessing the Implications of Water Harvesting Intensification on Upstream-Downstream Social-Ecological Resilience: A case study in the Lake Tana Basin Yihun Dile a,b , Raghavan Srinivasan c , Louise Karlberg b , and Johan Rockstrm a a Stockholm

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Assessing the Implications of Water Harvesting Intensification on Upstream-Downstream Social-Ecological Resilience: A case study in the Lake Tana Basin

Yihun Dilea,b, Raghavan Srinivasanc, Louise Karlbergb, and Johan Rockströma

aStockholm Resilience Center, Stockholm University, Stockholm, Sweden bStockholm Environment Institute, Stockholm, Sweden cTexas A&M University, Texas, USA

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Rationales

  • Rainfall variability – dryspells and droughts

Dry spells Drought

  • Water harvesting systems can bridge this rainfall variability

 In-situ water harvesting  Ex-situ water hatvesting

?

Upstream-downstream implications

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SLIDE 3

Research Area

WH suitability study Hydrological Modelling Understanding implications

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4

Data

Land cover types Area (% of basin) Dominantly cultivated 51.35 C2: Moderatly cultivated 22.34 Woodland open; Shrubland; Afro alpine; Forest 2.91 Grassland 2.83 Water body 20.19 FAO soil name Area (% of basin) Texture Eutric Leptosols 12.38 LOAM Haplic Nitisols 1.29 CLAY_LOAM Chromic Luvisols 16.00 CLAY_LOAM Eutric Vertisols 11.74 CLAY Eutric Cambisols 0.01 LOAM Eutric Fluvisols 9.79 LOAM Haplic Luvisols 20.62 LOAM Eutric Regosols 0.28 SANDY_LOAM Lithic Leptosols 2.86 CLAY_LOAM Haplic Alisols 4.77 CLAY

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  • Basin Area: 15129 km2
  • Total No subbasins: 959
  • Subasin sizes: 500-3000ha
  • Total No HRUs: 9963
  • Flow calibrated at 3 gauging stations
  • Climate data

 rainfall, Max & Min - 1990-2011  Global weather data – weather genrator

  • Evapotranspiration

 Hargreaves’s method

  • Surface runoff estimation

 Curve number method

  • Stream routing

 Variable storage method

  • Hydrological data

 1990-2007

Model setup and simulation

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Management

  • Two reserviors

Principal spillway Emergency spillway Elevation* Area(km2) Volume(Mm3) Elevation Area(km2) Volume(Mm3) Lake Tana 1784 2,766 20,300 1787 2983 29,100 Angereb Reservior 2135 0.5 3.53 2138 0.6 5.16

  • Tillage operations

 depth of till of 15cm, and  mixing efficiency of 0.3  tillage frequency of 4

  • Fertilizer application
  • Pescticide application

 2.4.D amine weed killer  1 liter/ha ~ 0.379kg/ha

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Model Calibration and Validation at Megech

NSE=0.76 PBIAS=4.0% NSE=0.74 PBIAS=40.2%

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  • Subbasins No.: 482
  • HRUs No.: 786
  • Total area: 10 sq.km
  • Subbasin size: 1-6ha
  • Climate data

 rainfall, Max & Min - 1990-2011

  • Evapotranspiration

 Hargreaves’s method  Global weather data – weather genrator

  • Surface runoff estimation

 Curve number method

  • Stream routing

 Variable storage method

Model setup and simulations

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Management

  • Ponds implemented as reserviors

 size that can store water for ONSEASON and OFFSEASON irrigation  size determined for combination of different climatic years & nutrient application

  • Crop rotation is applied

 ONSEASON (July-Dec) – TEFF  OFFSEASON (Jan-April) – Onion

  • Fertilizer

 Current fertilizer application for TEFF  Blankert fertilizer recommendation (MoAR) for TEFF  Blanker fertilizer recommendation for Onion

  • Pescticide application

 2.4.D amine weed killer  1 liter/ha ~ 0.379kg/ha

  • Tillage operations

 depth of till of 15cm, and  mixing efficiency of 0.3  tillage frequency of 4

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Water Harvesting Implementation Scenarios

Fir irst st cla lass ss su suit itabi ability lity – HRUs that consist of a slope<2%, Soil: Luvisols, and Vertisols; and agricultural

  • land. Area = 0.14km2 (1.14% of watershed)

Second econd clas lass s su suit itabil ability ity – HRUs of slope: <8%; Soil: Luvisols, and vertisols; and agricultural land. Area = 3.79km2 (38% of watershed) Thi hird cla lass ss su suit itabil ability ity – HRUs of slope: <12%; soil: Luvisols, and vertisols; and agricultural land. Area = 5.07km2 (51% of watershed) Nut utrient ient sc scenari enarios

  • s
  • Cu

Curr rrent ent nutrie rient nt ap applica cation ion ra rate  TEFF – 1st stage: UREA - 15kg/ha and DAP – 15kg/ha 2nd stage: UREA – 15kg/ha Onion – 1st stage: UREA – 85kg/ha, and DAP – 30kg/ha 2nd stage: UREA – 85kg/ha

  • Blanket

et Nutrient ient Reco commendat endation ion (B (BNR1) )  TEFF – 1stage: UREA – 50kg/ha, and DAP – 30kg/ha 2nd stage: UREA – 50kg/ha  Onion – 1st stage: UREA – 85kg/ha, and DAP – 30kg/ha 2nd stage: UREA – 85kg/ha

  • Blanket

et Nutrient ient Reco commendat endation ion (B (BNR2) )  TEFF – 1st stage: UREA – 85kg/ha, and DAP – 30kg/ha 2nd stage: UREA – 85kg/ha  Onion – 1st stage: UREA – 85kg/ha, and DAP – 30kg/ha 2nd stage: UREA – 85kg/ha

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Change in crop yield (%)

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Change in crop yield (%)

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Change in biomass (%)

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Change in biomass (%)

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Onion production (ton/ha)

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year IRR VOL(m^3) WYLD(m^3) percentage 1995 (drier) 532,485.68 1,839,334.07 28.95 2000 (wetter) 309,326.90 7,063,383.30 4.38

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Discussion and conclusion

U/S Benefits/costs D/S Benefits/costs Crop yield +++ + Biomass +++ + Soil loss ++ ++ Low flows + ++ Peak flows + ++ Total flow -

Win-Win

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Thank you