Y.S. Ramakrishna

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Drought Management
CRIDA
Y.S. Ramakrishna Director
Central Research Institute for Dryland
Agriculture Santosh Nagar, Hyderabad 500 059
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Probability of drought occurrence
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Probability of occurrence of severe droughts
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Impacts of drought
Environmental
Societal
Social

• Moisture stress
• Drinking water shortage
• Degradation of resources
• Increased pollution
• (both air and water)

• Malnutrition
• Ill-health
• Migration
• Debts

Economic

• Fall in Ag. Production
• Reduced income
• Loss of livestock
• Fall in output
• Unemployment
• Shortage of essential goods

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METHODOLOGIES FOR ASSESSMENT
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Methodologies
Aridity Anomaly Index (AI)

• This index is calculated on the basis of
  Thornthwaits water balance.
• This is the ratio of water deficit (PET-AET) to
  water need (PET).
• The departure of the index from the normal
  expressed as percentage of the normal is called
  Aridity Anomaly index.

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Methodologies

• Palmer Drought Severity Index (PDSI)
• This index is based on a two layer water balance
  model.
• He introduced the concept of CAFEC (Climatically
  Appropriate For Existing Conditions)
  precipitation which is a normal value for the
  established human activities of the place.
• The anomaly between actual and CAFEC rainfall is
  used as a drought indicator.
• To make this anomaly comparable is space and
  time, it is multiplied by a weighting factor K
  which depends on average moisture demand and
  supply and mean of the absolute values of the
  anomaly of the place.
• He devised a scale which ranged from 4 to 4 on
  the basis of which droughts were classified.

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Methodologies
Soil Moisture Deficit Index (SMDI)

• This index is based on crop specific soil water
  balance model.
• Soil moisture deficit ratio is calculated for a
  given period based on long term mean soil
  moisture, maximum and minimum available soil
  water.
• SMDI is calculated following Palmers (1965)
  procedure.
• This index can be classified into specific ranges
  as in the case of PDSI.

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Methodologies
Standard Precipitation Index (SPI)

• Two parameter incomplete gamma distribution is
  fitted to the long term rainfall data to
  normalize the series.
• The cumulative probabilities are then transformed
  into standardized normal variables with mean of
  zero and standard deviation of one using inverse
  normal distribution, so the values of the SPI are
  in standard deviations.
• Positive values indicate greater than median
  precipitation and negative values indicate less
  than median precipitation.
• Being independent of the magnitude of mean
  rainfall, it is comparable over a range of
  climatic zones.

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Methodologies
Comparison of different indices
Index Input requirements Remarks
PDSI Weekly / monthly rainfall PET, AWC Requires long series of data
AI Weekly / monthly rainfall PET, AWC Requires long series of data
SMDI Daily rainfall and PET crop coefficients, AWC Requires long series of data
SPI Weekly / monthly rainfall (can be calculated for multiple time scales) Requires long series of data
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Other drought indices

• R index R/PE less than 0.40
• Z index (R-Rca).w
• WRSI (FAO) WD/ TWR 100
• SDD Tc-Ta
• NDVI (IR-R)/(IRR)

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Types of Agricultural Droughts
Early season Delayed onset, prolonged dry
spells after onset Mid-season Inadequate
soil moisture between two rain events Late
season Early cessation of rains or
insufficient rains
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Agricultural drought classification
AE/PE () in Phenophase Drought intensity Code S V R Code S V R Code S V R
76 100 Nil S0 V0 R0
51 75 Mild S1 V1 R1
26 50 Moderate S2 V2 R2
25 or less Severe S3 V3 R3
S Seedling V Vegetative R Reproductive
S1V3R2 A2 (moderate) S0V1R1 A1 (mild)
Source Ramanarao et al, 1981
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Drought Management A Case Study from Andhra
Pradesh Approach
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Methodologies

• Criteria for identification of drought affected
  areas
• Various states have been following different
  norms for the declaration of drought.
• For example
• In A.P. following criteria has been used
• Deficiency of rainfall
• Deficiency of rainfall of 25 and above in
  Mandals where the annual rainfall is more than
  1000 mm.
• 20 and above, where the annual rainfall is 750
  mm 1000 mm.
• 15 and above where the annual rainfall is less
  than 750 mm.

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Methodologies
Any two of the remaining norms

1. Compression / reduction in the cropped area of
   50 and above under all principal crops.
2. Normal reduction in crop yields of 50 and above
   in comparison with average yields of preceding 5
   years.
3. Dry spell and its impact on crops.

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   Parameters considered for prioritization of
mandals for taking of drought mitigation
activity     1.     Average Rainfall
2.     Coefficient of variation of
rainfall 3.     Meteorological drought
frequency 4.     Hydrological drought
frequency 5.     Agricultural drought
frequency 6.     Ground Water Status 7.     Feed
and Fodder availability 8.     Percent Irrigated
Area (Kharif) 9.     Percent Irrigated Area
(Rabi) 10. Rural Water Supply (percent
habitations fully covered) 11. Drought Severity
(agriculture)     Note 1. The developmental /
relief measures should be given preference as for
the priority. The Priority I mandals should get
maximum preference and Priority IV
the least. 2. The ranks given to the
individual parameters are flexible and the user
has the option to change the ranks by using the
Ranking Software.  
3. Most of the mandals fall under Priority II and
Priority III categories
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intensified
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FOREWARNING
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Forewarning Software
  INPUT 1.    Rainfall 2.  Pan evaporation
(mm) maximum and minimum temperature (if pan
evaporation is not available i.e. for
calculation of potential
evapotranspiration) 3.    Crop coefficient 4.   
Yield response factor 5.    Available water
holding capacity (AWC) of the soil 6.    Latitude
and longitude of the mandal (if pan evaporation
is not available) 7.    Maximum yield of crop
8.    Duration of the crop OUTPUT 1.      Soil
moisture 2.      Runoff 3.      Deep
drainage 4.      Moisture adequacy index 5.     
Water requirement satisfaction index 6.     
Yield compared to normal 7.      Drought signals 
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Drought Signal If MAI on any day is less than
0.75 it gives ALARM If number of days with MAI lt
0.75 is 10 ? Gives signal
1 i.e. mild drought signal If number of days
with MAI lt 0.75 is 20 ? If number of days with
MAI lt0.5. is 10 ? Gives signal 2 i.e. moderate
drought If number of days with MAI
lt0.75 is 30
If number of days with MAI lt 0.50 is 20
? If
number of days with MAI 0.25 is 10 Gives signal
3 i.e. severe drought
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CROP STRATEGY
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MITIGATION
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BLACK GRAM
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ALTERNATE LAND USE MODEL DSS
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Drought Mitigation Strategies

• Policy support at national and state level
• Developmental funding to rural development and
  special assistance during natural calamities
• Input supply, access to credit and marketing and
  price support
• Farm advisory services
• Non-Government Agencies like
• NGO, CBO, SHG, Philanthropic bodies and aid
  agencies
• Major focus
• Education, building of awareness creation and
  community institutions and leadership
• Supplementing the Government effort in rural
  development

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Short-term/Immediate measures

• Execution of labour-oriented schemes for
  employment generation and implementation of
  relief and development works National Rural
  Employment Guarantee Act (NREGA) programme
• Good weather code encashing production from
  good rainfall regions and managing low rainfall
  regions through transport of food grains from
  high production areas
• Establishment of Fodder/Seed/Grain banks
• Establishment of Cattle camps near water points

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Long-term measures

• Long-range forecasting of rains (2-4 months in
  advance)
• Regional analysis of rainfall patterns
• Crop weather watch programs
• Value-added Agro-Advisories
• Integrated watershed development
• Land use diversification
• Water harvesting
• In-situ moisture conservation

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RISK TRANSFER
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Risk Management and Crop Insurance

• Government sponsored National Agricultural
  Insurance Scheme (NAIS) in operation since Rabi
  1999-2000.
• Farm Income Insurance Scheme (FIIS) implemented
  on pilot basis in Rabi 2003-04 and Kharif 2004.
  Discontinued w.e.f. rabi 2004-05.
• Insurance linked to crop loan
• Varsha Bima Yojana (Rainfall Insurance) being
  implemented by some insurance companies like
  ICICI- Lombard, IFFCO-Tokio, AIC on Pilot basis.

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Weather-based Insurance

• No state is immune to natural calamities
• 12 million hectares of land damaged every year by
  natural calamities
• Agricultural Insurance is an important risk
  management tool
• Agricultural Insurance Company of India Ltd.
  (AIC) formed on January 1, 2006

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Weather Index Insurance
Constraints

• High spatial and temporal viability in rainfall
• Wide variation from village to village
• Recording of rainfall at mandal level which is
  not representative
• Mandals or group of mandals are considered as
  unit
• Lack of transparency in recording and exchange of
  data

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Weather Index Insurance - Rainfall

• Advantages
• Indemnity based on rainfall not on an individual
• Applicable to several crops
• Speedy settlement and transparency
• Weather indices could be deficit or excessive
  rainfall
• Disadvantage
• Recurring droughts would make it more expensive

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Looking Ahead

• Scaling up to states most vulnerable to drought
  namely Rajasthan, Karnataka, AP and Maharashtra
• Inclusion of more partners and consortium
  approach
• Consortium partners could be CRIDA, CAZRI, SAUs
• IIT-Bombay
• NRSA, CGWB
• State Remote Sensing Centers
• Proposed source of funding to be
• NIDM

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Thank You