Assessing the Implications of Water Harvesting ... ?· Assessing the Implications of Water Harvesting…

Download Assessing the Implications of Water Harvesting ... ?· Assessing the Implications of Water Harvesting…

Post on 05-Sep-2018

212 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • 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 Rockstrma

    aStockholm Resilience Center, Stockholm University, Stockholm, Sweden bStockholm Environment Institute, Stockholm, Sweden

    cTexas A&M University, Texas, USA

  • 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

  • Research Area

    WH suitability study Hydrological Modelling Understanding implications

  • 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

  • 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 Hargreavess method

    Surface runoff estimation Curve number method

    Stream routing Variable storage method

    Hydrological data 1990-2007

    Model setup and simulation

  • 6

    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

  • Model Calibration and Validation at Megech

    NSE=0.76 PBIAS=4.0%

    NSE=0.74 PBIAS=40.2%

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

    Climate data rainfall, Max & Min - 1990-2011

    Evapotranspiration Hargreavess method Global weather data weather genrator

    Surface runoff estimation Curve number method

    Stream routing Variable storage method

    Model setup and simulations

  • 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

  • Water Harvesting Implementation Scenarios First class suitability HRUs that consist of a slope

  • Change in crop yield (%)

  • Change in crop yield (%)

  • Change in biomass (%)

  • Change in biomass (%)

  • Onion production (ton/ha)

  • 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

  • Discussion and conclusion

    U/S Benefits/costs D/S Benefits/costs

    Crop yield +++ + Biomass +++ + Soil loss ++ ++ Low flows + ++ Peak flows + ++ Total flow -

    Win-Win

  • Thank you

Recommended

View more >