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

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Agriculture drought with remote sensing

  1. 1. Agricultural Drought Monitoring with Remote Sensing Dr Yan Nana Institute of Remote Sensing Applications (IRSA) Chinese Academy of Sciences (CAS)
  2. 2. Introduction <ul><li>Drought is the most serious disaster damaging crop </li></ul><ul><li>Establish drought monitoring system at Ministry of water resources </li></ul><ul><li>The system consists of three components </li></ul><ul><ul><li>Meteorological Model (6 indices) (1996- </li></ul></ul><ul><ul><li>Hydrological model (2 indices) (2005- </li></ul></ul><ul><ul><li>Remote sensing (4 indices) (2005- </li></ul></ul>
  3. 3. Methods <ul><li>Visible </li></ul><ul><li>Visible and Near infrared </li></ul><ul><li>Thermal infrared </li></ul><ul><li>Microwave </li></ul><ul><li>Albedo </li></ul><ul><li>Vegetation Index </li></ul><ul><li>Surface temperature </li></ul><ul><li>Backscatter coefficient </li></ul><ul><li>Indices </li></ul><ul><ul><li>Visible and Near Infrared : NDVI, VCI, BMVCI </li></ul></ul><ul><ul><li>Shortwave Infrared : NDWI </li></ul></ul><ul><ul><li>Thermal Infrared: CWSI , TCI , DSI </li></ul></ul><ul><ul><li>Visible 、 Near Infrared and Thermal Infrared : Ts/NDVI , TVDI , VTCI </li></ul></ul><ul><ul><li>Microwave remote sensing: soil moisture </li></ul></ul><ul><li>…… </li></ul>
  4. 4. DroughtWatch System <ul><li>Remote sensing data :AVHRR/MODIS </li></ul><ul><li>Indices: VCITCINDWI VHI </li></ul><ul><li>Preprocessing </li></ul><ul><ul><li>Geometric correction </li></ul></ul><ul><ul><li>Atmosphere correction </li></ul></ul><ul><ul><li>BRDF correction </li></ul></ul><ul><li>Surface parameters calculation </li></ul><ul><ul><li>Cloud removal, NDVI, surface temperature, Albedo </li></ul></ul>
  5. 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. 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. 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. 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. 9. NDWI (Normalized Difference Water Index) May,2003 NDWI dataset Cloud removal
  10. 10. <ul><li>VHI= aVCI+bTCI </li></ul><ul><ul><li>VHI: considering vegetation condition and the surface temperature change simultaneously; </li></ul></ul><ul><ul><li>a,b are the weight coefficient of indices. </li></ul></ul><ul><ul><ul><li>a=R 2 vci /( R 2 vci + R 2 tci ) ;b=R 2 tci/( R 2 vci + R 2 tci ) </li></ul></ul></ul><ul><ul><ul><li>R 2 vci : R 2 between VCI and relative soil moisture </li></ul></ul></ul>VHI
  11. 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. 12. <ul><li>Study area: Shanxi </li></ul><ul><li>Data </li></ul><ul><ul><li>Soil moisture data: 2002-2005, seventy stations </li></ul></ul><ul><ul><li>Indices: 2002 -2005, seventy stations </li></ul></ul>Soil Moisture inversion Shanxi <ul><li>The relation between VCI, TCI and relative soil moisture: </li></ul><ul><ul><li>relative soil moisture = soil water content/field capacity </li></ul></ul>
  13. 13. Soil Moisture Daily TCI and Soil Moisture 10 days TCI and soil Moisture
  14. 14. Soil Moisture Daily VCI and Soil Moisture 10 days VCI and soil Moisture
  15. 15. Soil Moisture Daily VHI and Soil Moisture 10 days VHI and soil moisture VHI= a TCI + b VCI
  16. 16. Soil Moisture Daily NDWI and Soil Moisture
  17. 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. 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. 19. Soil Moisture Ground Measurement Points
  20. 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. 21. Validation of drought monitoring results <ul><li>Validation area: Taigu,Shanxi </li></ul><ul><ul><li>Data required: </li></ul></ul><ul><ul><li>Indices,2003~2005, day and ten-days </li></ul></ul><ul><ul><li>Day soil moisture, 2003-2005, two depth of 10CM and 20CM </li></ul></ul><ul><ul><li>Ten-days soil moisture,2003-2005 </li></ul></ul>5km Sample allocation Observation point 100m 40m 40m 10m 10m 40m 40m 10m 10m
  22. 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. 23. DroughtWatch   Upgrading: AVHRR to MODIS MODIS to MERSI Pre-processing DroughtIndex DroughtGrade Statistics
  24. 24. Operational Products Percent of different drought grads different provinces of China (April, 2006)
  25. 25. <ul><li>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. </li></ul><ul><li>Since Feb 16, the drought area had a large decrease because of precipitation and irrigation in large area of the north plain </li></ul>Drought monitoring in North Plain In early spring, 2009 January 21-31 February 1st-10 February 11-16 February17-22
  26. 26. <ul><li>In august, drought area expanded rapidly in the north-west of Liaoning and the west of Jilin, and mostly are minor drought </li></ul><ul><li>The drought area percentage are 20.9 % and 15.2 in Liaoning and Jilin respectively </li></ul>Drought monitoring in Dongbei from July to August,2009
  27. 27. On-going research <ul><li>Incorporate HJ data, CCD to increase resolution for better monitoring </li></ul><ul><li>Microwave data for soil moisture </li></ul><ul><li>Develop new indices: combination of optical and microwave data </li></ul>
  28. 28. Scale issues
  29. 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. 30. <ul><li>Fast drought monitoring in region scale </li></ul><ul><li>Drought monitoring in local scale </li></ul>
  31. 31. Conclusion <ul><li>RS is only way to monitor Drought </li></ul><ul><li>Need ground data to calibrate the model </li></ul><ul><li>High Resolution for disaster reduction </li></ul><ul><li>Soil Moisture is not a good indicator for all crop season, new indicator should be found </li></ul>
  32. 32. Thanks for Attention !