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Agriculture drought with remote sensing

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Presented in “China – Thailand Geo-Informatics Workshop Series I: Agricultural Applications” 30 June - 2 July 2010 at Pattaya, Thailand

Presented in “China – Thailand Geo-Informatics Workshop Series I: Agricultural Applications” 30 June - 2 July 2010 at Pattaya, Thailand

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  • 1. Agricultural Drought Monitoring with Remote Sensing Dr Yan Nana Institute of Remote Sensing Applications (IRSA) Chinese Academy of Sciences (CAS)
  • 2. Introduction
    • Drought is the most serious disaster damaging crop
    • Establish drought monitoring system at Ministry of water resources
    • The system consists of three components
      • Meteorological Model (6 indices) (1996-
      • Hydrological model (2 indices) (2005-
      • Remote sensing (4 indices) (2005-
  • 3. Methods
    • Visible
    • Visible and Near infrared
    • Thermal infrared
    • Microwave
    • Albedo
    • Vegetation Index
    • Surface temperature
    • Backscatter coefficient
    • Indices
      • Visible and Near Infrared : NDVI, VCI, BMVCI
      • Shortwave Infrared : NDWI
      • Thermal Infrared: CWSI , TCI , DSI
      • Visible 、 Near Infrared and Thermal Infrared : Ts/NDVI , TVDI , VTCI
      • Microwave remote sensing: soil moisture
    • ……
  • 4. DroughtWatch System
    • Remote sensing data :AVHRR/MODIS
    • Indices: VCITCINDWI VHI
    • Preprocessing
      • Geometric correction
      • Atmosphere correction
      • BRDF correction
    • Surface parameters calculation
      • Cloud removal, NDVI, surface temperature, Albedo
  • 5. VCI (Vegetation Condition Index) NDVIj: NDVI of date j ; NDVImax: the maximum NDVI of all dataset ; NDVI min :the minimum NDVI of all dataset ; May,2003 The maximum and minimum NDVI calculation
  • 6. NDVImax and NDVImin Daily NDVI dataset (1991-2004) Cloud removal Crop NDVI range The maximum and minimum NDVI dataset Cloud channel growth season NDVI (0.15~0.8)
  • 7. TCI (Temperature Condition Index) TCI, Early May 2003 Tsj surface temperature of date j ; Tmax the maximum temperature of all dataset ; Tmin the minimum temperature of all dataset ; Tmax and Tmin
  • 8. Tmax and Tmin Cloud ID The range of T0 based on the drought district DEM Ts Dataset(1991-2005) Cloud removl T thresh Tmax and Tmin dataset DEM correction
  • 9. NDWI (Normalized Difference Water Index) May,2003 NDWI dataset Cloud removal
  • 10.
    • VHI= aVCI+bTCI
      • VHI: considering vegetation condition and the surface temperature change simultaneously;
      • a,b are the weight coefficient of indices.
        • a=R 2 vci /( R 2 vci + R 2 tci ) ;b=R 2 tci/( R 2 vci + R 2 tci )
        • R 2 vci : R 2 between VCI and relative soil moisture
    VHI
  • 11. Soil Water Holding Capacity 0-10cm 田间持水量图 10-20cm 田间持水量图 Station Map and soil type map 178 stations
  • 12.
    • Study area: Shanxi
    • Data
      • Soil moisture data: 2002-2005, seventy stations
      • Indices: 2002 -2005, seventy stations
    Soil Moisture inversion Shanxi
    • The relation between VCI, TCI and relative soil moisture:
      • relative soil moisture = soil water content/field capacity
  • 13. Soil Moisture Daily TCI and Soil Moisture 10 days TCI and soil Moisture
  • 14. Soil Moisture Daily VCI and Soil Moisture 10 days VCI and soil Moisture
  • 15. Soil Moisture Daily VHI and Soil Moisture 10 days VHI and soil moisture VHI= a TCI + b VCI
  • 16. Soil Moisture Daily NDWI and Soil Moisture
  • 17. Comparison results The relation between indices and soil moisture VHI > TCI >VCI>NDWI R 2 between VCI and soil moisture at 10cm and 20cm respectively is 0.45,0.26 R 2 between TCI and soil moisture at 10cm and 20cm respectively is 0.58 , 0.48 ; R 2 between VHI and soil moisture at 10cm and 20cm respectively is 0.6 , 0.42; R 2 between NDWI and soil moisture at 10cm and 20cm respectively is 0.21 , 0.16;
  • 18. Region Suitability 全国旱情区划基本单元制作流程图 Drought zone geomorpho+Soil Cluster Climate Cluster Overlay
  • 19. Soil Moisture Ground Measurement Points
  • 20. DroughtIndex Suitability 不同旱情区划单元指数适应性表 : T 表示 TCI , V 表示 VCI , H 表示 VHI , 后的指数为次最佳指数
  • 21. Validation of drought monitoring results
    • Validation area: Taigu,Shanxi
      • Data required:
      • Indices,2003~2005, day and ten-days
      • Day soil moisture, 2003-2005, two depth of 10CM and 20CM
      • Ten-days soil moisture,2003-2005
    5km Sample allocation Observation point 100m 40m 40m 10m 10m 40m 40m 10m 10m
  • 22. Validation of drought monitoring results Depth TCI_R 2 VCI_R 2 NDWI_R 2 VHI_R 2 10cm Soil moisture 0.93 0.66 0.08 0.97 20cm Soil moisture 0.91 0.60 0.15 0.92
  • 23. DroughtWatch   Upgrading: AVHRR to MODIS MODIS to MERSI Pre-processing DroughtIndex DroughtGrade Statistics
  • 24. Operational Products Percent of different drought grads different provinces of China (April, 2006)
  • 25.
    • Because consecutive days without rain and snow reached more than 80 days in the north plain, the area percentage of wheat drought between January 20 and February 16 were 49.5%, 36.9% and 30.5%, respectively.
    • Since Feb 16, the drought area had a large decrease because of precipitation and irrigation in large area of the north plain
    Drought monitoring in North Plain In early spring, 2009 January 21-31 February 1st-10 February 11-16 February17-22
  • 26.
    • In august, drought area expanded rapidly in the north-west of Liaoning and the west of Jilin, and mostly are minor drought
    • The drought area percentage are 20.9 % and 15.2 in Liaoning and Jilin respectively
    Drought monitoring in Dongbei from July to August,2009
  • 27. On-going research
    • Incorporate HJ data, CCD to increase resolution for better monitoring
    • Microwave data for soil moisture
    • Develop new indices: combination of optical and microwave data
  • 28. Scale issues
  • 29. Soil moisture inversion based on active microwave radiometer Soil moisture in Yucheng based on Radarsat2 , August 28,2008 Water Cloud Model Mv is vegetation watercontent , Ms is soil water content , θ is incidence angle, a,b,c,d are coefficients
  • 30.
    • Fast drought monitoring in region scale
    • Drought monitoring in local scale
  • 31. Conclusion
    • RS is only way to monitor Drought
    • Need ground data to calibrate the model
    • High Resolution for disaster reduction
    • Soil Moisture is not a good indicator for all crop season, new indicator should be found
  • 32. Thanks for Attention !