1. Irrigated Areas of China based on Satellite Sensors and National Statistics: Issues and Way forward from Global Irrigated Area Mapping By Xueliang Cai, GIAM core team http://www.iwmigiam.org GIAM2007 China Workshop Global Irrigated Area Mapping with Focus on China (GIAM China)May 23rd, 2007, Beijing

2.

The issues:

• Irrigated areas from remote sensing

• Irrigated areas from national statistics

• The comparison

• Understanding the differences

• The way forward

3. 1. Irrigated areas from Remote Sensing 4. 1. Irrigated areas from Remote SensingGlobal irrigated area map China irrigated area map TAAI* AIA* Rainfed area Total cropland area Watering method Irrigation type Crop type Scale intensity Spatial distribution * TAAI : Total Area Available for Irrigation,AIA : Annualized Irrigated Area Source: IWMI, 2006 Source: IWMI, 2006 5. 2. Irrigated areas from national statistics 6. 2. Irrigated areas from national statistics the Ministry ofLand and Resourcesthe Ministry ofWater Resources the Ministry ofAgricultureNational land uses statistics National irrigation statistics National agricultural statistics Sources: 7. 2. Irrigated areas from national statistics

Field measurements for all units

Summarized @ various administrative units (village => township => county => province => nation)

Large scalefield survey Down-top reporting

Field measurement /estimation forchangedareas

Reporting to upper administrative units (village => township => county => province => nation)

Methods: 8. 2. Irrigated areas from national statistics Total crop land areas decrease Effective irrigated areas increase Source:Statistical Bulletin on China Land Resources, 2007 9. 3. GIAM China vs. national statistics:the comparison 10. 3.GIAM China vs. national statistics:the comparison Source: CHINA NATURAL RESOURCES DATABASE, CAS 129,205,000 N.A. N.A. 203,624,473 Total Cropland Area 75,805,000 N.A. N.A. 91,635,702 Total Rainfed Area 53,400,000 53,740,000 53,823,000 111,988,772 Total Area Available for Irrigation N.A. N.A. N.A. 151,802,086 Annualized Irrigated Area N.A. N.A. N.A. 7,688,411 Continuous Irrigated Area N.A. N.A. N.A. 68,233,355 Season2 Irrigated Area N.A. N.A. N.A. 75,880,320 Season1 Irrigated Area (ha) (ha) (ha) (ha) National statistics (1) FAO Aquastat FAO/UF (GMIAV3.0) GIAM 10 km Type 11. 3.GIAM China vs. national statistics:the comparison Source: CHINA NATURAL RESOURCES DATABASE, CAS 12. 4. GIAM China vs. national statistics:Understanding the differences 13. 4.1Definition Issues 4. Understanding the differences 14. 4. Understanding the differences

Irrigated area the definition

• Irrigated area

• • Low land (rice, lotus, etc. )

• • Irrigated upland

• Effective irrigated area

• Actual effective irrigated area

• TAAI

• AIA

• Class naming

15. 4.2Limitation in National Statistics 4. Understanding the differences 16.

Advantages:

Accurate

Detailed

Disadvantages:

Time consuming

Human sources consuming

Difficult to update

4. Understanding the differences Large scalefield survey Down-top reporting

Advantages:

Easy

Low cost

updatable

Disadvantages:

Inaccurate

Limitation of national statistics No spatial distribution information 17.

Limitation of national statistics

4. Understanding the differences

Inconsistent area unitsmu(varies from 667 to 1500m 2 )

Benefit driving factors (to evade taxes or water fees)

Area measurement/estimation errors

Compilation errors

Illegal land use change

18.

Decrease of large irrigation system command area

4. Understanding the differences Zhanghe Irrigation system, Hubei Existing irrigated area decrease in national statistics Source: IWMI project, 2005 New boundary Old boundary 19. Irrigated,small reservoirs , Rice, Single crop Irrigated,groundwater , rice, double crop Irrigated,small tanks , Rice, Single crop Areas in color are outside the CBIP irrigated area map..what type of irrigation exist here?. 4. Understanding the differences Informal irrigation Source: IWMI, 2006 20. 4. Understanding the differences

Informal irrigation missing in national statistics

Increase of small storages

Limited development for large irrigation system,many local water storages are constructed in recent years Ponds construction years Source: IWMI 2005, More Rice with Less Water Size distribution of water bodies in 1978 and 2001 , ZIS, Hubei 100 Total 35 2000- 2003 35 1991-1999 30 1965-1990 Percent Year of construction 21. 4.3Limitation in GIAM 4. Understanding the differences 22. 4. Understanding the differences local fractions Global fractions Global irrigated area fractions (IAF G ) are computed for large areas (e.g., sub-continent, world). Local irrigated area fraction (IAF L ) fractions are more relevant when computing areas for the local areas (e.g., state, district). Irrigated Area Fraction IAF localization Source: IWMI, GIAM Project, 2006 23.

Refinement of GIAM Resolution effects

MODIS 500 m Landsat 30 m AVHRR 10 km Syr Darya River Basin, Central Asia Finer the resolution greater the area 4. Understanding the differences Source: IWMI, GIAM Project, 2006 3,105,308AVHRR 10km3,459,126MODIS 5004,086,856Landsat 30mArea ( ha) Satellite/Sensor 24.

Refinement of GIAM Resolution effects

AVHRR 10 km MODIS 500 M LANDSAT 30 M Ruhuna river basin, Sri Lanka 4. Understanding the differences Source: IWMI, GIAM Project, 2006 0.12 GIAM 30 m 0.09 GIAM 500 m 0.079 GIAM 10 km Area in M ha Map at different scales 25. Misrepresentation of minimum mapping unit 10 km 10 km AVHRR 10 km MODIS 500 mLANDSAT 30 m Irrigated area: 5199 ha Irrigated area: 5822 ha Irrigated area:6559 ha 4. Understanding the differences Source: IWMI, GIAM project, 2006 Nagarjunasagar Command area Irrigated area Other LULC 26.

Abandoned canals

4. Understanding the differences Abandoned/changed cropland (canal system damaged but may still exists) Damaged canal Abandoned canal May still be interpreted as irrigated Photo Credit: IWMI, More Rice with Less Water, 2005 27. 5. GIAM China: the way forward 28. GIAM China: the way forward Issues to address in irrigated area mapping

Definition of irrigation

Identify national statistics terms

Identify GIAM terms

Identify the gap and linkages

Other secondary data sources collection

Ground truth data collection

29.

Ground truth data collections

Understanding the differences More GT points needed for extremely complicated China irrigated areas Source: IWMI, GIAM Project, 2006 30. GIAM China: the way forward

Ground truth data collections

Ground truth points

Country boundary Total GT points:1132 Example: Ground Truth Data used in GIAM India 500m Source: :IWMI, GIAM project, 2006 31. GIAM China: the way forward

More accurate areas

More detailed crop types

Better spatial distribution

Multi-scales to finer resolutions GIAM 10km GIAM 500m GIAM 30m Map and establish Statistics at different Resolutions Source: IWMI, GIAM Project, 2006 32. GIAM China: the way forward Finer resolution: 500m (MODIS) Source: IWMI, GIAM Project, 2006 33. GIAM China: the way forward Forests Rainfed-agriculture-millets Rangelands-grasslands Irrigated-conjunctive-cotton Plantations with rice Fishponds-Aquaculture Finer resolution: 30m (LandSat ETM) Source: IWMI, GIAM Project, 2006 34. GIAM China: the way forward

Provide irrigated area maps @ various scale/resolution

Provide statistics @ various administrative units

Operational system with online access to all users

Updated every 2~5 years (preferably)

Freely high quality data sources

Irrigated area mapping and reporting system for China (IAMRS China) 35. GIAM China: the way forward GIAM main web portal Source: IWMI, GIAM Project, 2006 36. GIAM China: the way forward GIAM China Rain fed croplandarea mapping Wet land mapping Drought monitoring Water productivitymapping Institutionsand policies 37. Thank you www.iwmigiam.org