Multi-dimensional nature of drought in Abbay/Upper Blue Nile Basin - - PowerPoint PPT Presentation

08/20/2020

DEVELOPING AN IMPACT-BASED COMBINED DROUGHT INDEX FOR MONITORING CROP YIELD ANOMALIES IN THE UPPER BLUE NILE BASIN, ETHIOPIA

By: Yared A. Bayissa, Semu A. Moges, Assefa M. Melesse, Tsegaye Tadesse, Anteneh Z. Abiy

Multi-dimensional nature of drought in Abbay/Upper Blue Nile Basin and the importance

• f regional coordination efforts for mitigation

International Conference on the Nile and Grand Ethiopian Renaissance Dam: Science, Conflict Resolution and Cooperation

August 20-21, 2020

Outline

— Background — Drought history of the UBN basin — Material and methods — Spatial and temporal features of different types of droughts — Drought impact on socio-economic — Summary and recommendation

9/10/20

— Historic droughts in Ethiopia

— 1983/84 was one of the worst drought

events

— Covered large area and affected many

populations

— Drought has become more frequent — Now it occurs every 2 to 3 years

9/10/20

(Source: Economics of resilience to drought: Ethiopia analysis (USAID report, 2018))

— Drought impacts on Ethiopia economy

— The economy is less resilient to

drought

— The economy is highly linked to

annual rainfall variability

(Data source: EM-DAT: The International Disaster Database. Centre for Research

• n the Epidemiology of Disasters-CRED)

Background

9/10/20 Natural Climate Variability Precipitation deficiency (amount, intensity, timing) High temp, high winds, low relative humidity (amount, intensity, timing) Reduced infiltration, runoff, deep percolation, and GW Increased evaporation and transpiration Soil Water Deficiency Plant water stress, reduced biomass and yield Reduced streamflow, inflow to reservoirs, lakes, and ponds; reduced wetlands, wildlife habitat Economic impact Social Impact Environmental impact Hydrological Agricultural Meteorological drought drought drought

D u r a t i

• n

Cont’d …

Proceeding of precipitation deficit throughout the Hydrological cycle (Rasmusson, 1993) Influence of precipitation deficiency and other factors on drought development (National Drought Mitigation Center)

Demonstrate the different forms of droughts that

• ccurred in the Abbay/ Upper Blue Nile River basin and

its national and regional implication

9/10/20

Cont’d …

6 9/10/20

• UBN basin is vulnerable to drought
• 1984, 2002, 2009 and 2015 drought years
• The eastern part more drought susceptible
• Regional cooperation is vital to mitigating its impact

Drought history of the UBN basin

9/10/20

Material and methods

— Drought indices

— Standardized Precipitation Index — Soil Moisture Deficit Index — Surface Runoff Index

9/10/20

Soil Moisture Deficit Index (SMDI)

Agricultural drought assessment

Land Data Assimilation System (FLDAS)

(Monthly soil moisture time series) Soil Moisture Deficit Index (SMDI)

• Seasonal
• Annual time scales

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Generating maps

Standardized Runoff Index (SRI)

Drought category Index value Near Normal 0.50 - -0.49 Mild drought

• 0.50 - -0.99

Moderate drought

• 1.00 - -1.49

Severe drought

• 1.50 - -1.99

Extreme drought < -2.00

Cont’d …

Long-term Stream flow Surface Runoff Index (SRI)

• Seasonal
• Annual

Hydrological drought assessment

9/10/20

• Similar drought pattern b/n SPI and stdSMDI in 1984 and 2015
• Wide spread and severe drought is shown by stdSMDI as compared to SPI in 2002 and 2009

´

Extreme drought Severe drought Moderate drought Mild drought Near Normal Unusual Moist Moderate Moist Very Moist Extremely Moist UBN Basin Main River Lakes

Spatial features of meteorological and agricultural droughts

Seasonal SPI (JJAS) Seasonal stdSMDI (JJAS)

9/10/20

• Similar drought patterns as compared to seasonal for the selected years
• Relatively widespread and intensified drought condition in 1984, 2002 and 2009

´

Extreme drought Severe drought Moderate drought Mild drought Near Normal Unusual Moist Moderate Moist Very Moist Extremely Moist UBN Basin Main River Lakes

Cont’d …

Annual SPI Annual stdSMDI

1984 2002 2009 2015

1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Index values [-]

• 3
• 2
• 1

1 2 3

SPI stdSMDI SRI

1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 2020

Index values [-]

• 3
• 2
• 1

1 2 3

SRI SPI stdSMDI

9/10/20

Seasonal Annual

Temporal pattern of meteorological, agricultural and hydrological droughts

SPI SRI SRI 0.79 stdSMDI 0.56 0.64 Seasonal correlation coefficient SPI SRI SRI 0.85 stdSMDI 0.67 0.49 Annual correlation coefficient

• There is a high nexus between each drought type and all indices consistently

indicated the historic drought events in the basin.

1 2 3 4 5 6 7 8 9 10 11 12 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 Needy People [10^6] Year

Number of population in need for relief food assisstance (1982-2000)

Drought impact on socio-economic

9/10/20 (Source: Abate, 2003)

Summary and recommendation

— The nature of drought in Abbay/UBN

basin is multi-dimensional and occurring concurrently

— It has both complementary as well as

supplementary socio-economic impacts (agriculture, GDP)

9/10/20

— We

recommend constructing upstream storage facilities to delink drought induced socio-economic losses and to mitigate the multi-dimensional drought related disaster

— Understanding multidimensional aspects of drought

provides perspectives for regional cooperation and the need for shared drought management

08/20/2020

DEVELOPING AN IMPACT-BASED COMBINED DROUGHT INDEX FOR MONITORING CROP YIELD ANOMALIES IN THE UPPER BLUE NILE BASIN, ETHIOPIA

Multi-dimensional nature of drought in Abbay/Upper Blue Nile Basin and the importance

• f regional coordination efforts for mitigation

International Conference on the Nile and Grand Ethiopian Renaissance Dam: Science, Conflict Resolution and Cooperation