Crop Monitoring for Selenge Basin using RS and GIS

Crop Monitoring for Selenge Basin using RS and GIS

Sh. Munkhtuya¹, B. Oyuntulkhuur²
¹GIS Specialist, Information and Computer Center
²GIS Specialist, Land Management Agency
Ministry for Nature and Environment of Mongolia
Khudaldaany Str – 5, Ulaanbaatar 11, Mongolia
mtuya@yahoo.com

Mongolia has very extreme continental and dry windy climate and it locates in high altitude, specially the area 80 percents of the country locates in altitude more than 1000 m above sea level. Mongolian economy and agricultural activities are highly dependent from climate and its change. Approximately 800 thousand hectares of the territory is crop land.

In the past, mapping of agricultural land has limited the applications of aerial photographs and field study. The existing agricultural maps made in 1980’s. As an old aerial photographs and maps are unsuitable for updating or preparing new detailed land use maps and they do not satisfy farmers and government requests any more. Mongolian farmers need currents status of crop parcel map and by these reason we try to demonstrate possibility of crop parcel mapping using RS and GIS to decision makers.

Many studies have shown that satellite remote sensing technique is a powerful tool for agriculture monitoring.

Data Used
For crop monitoring used high resolution satellite data of main agricultural region Orkhon-Selenge Basin of Mongolia:

2 scenes of Landsat ETM from 21- Aug- 1989 covered the whole area of test site (Path:132, Row:25, 26)
2 scenes of Landsat ETM from 20- Sep – 2000 covered the whole area of test site (Path:132, Row:25, 26)

GIS Data

Main geographic features like administrative boundaries, lakes, roads, rivers, and relief (scale 1:500,000)
Land use map of Selenge aimag (scale 1:500,000)
Ecosystem map of Selenge region (scale 1:500,000)
Fire map, which produced from NOAA AVHRR data of 2000

Statistical Data

Local agronomist data
Parcel data from LMA, MAF and National Census

There are 7 soums selected for crop monitoring study (three from Selenge: Eroo, Orkhon and Tsagaannuur; three from Tuv: Jargalant, Tseel and Ugtaaltsaidam; one from Darkhan: Khongor).

Crop Parcel Mapping
Crop boundaries were precisely digitized from panchromatic and multispectral channels of Landsat E.TM image. During digitizing process new fields (small areas of vegetable and potato) were found and added from imagery.

For calculation of parcel area we used ARC/INFO 8.0 GIS software. Of course, the area received from imagery is very close to real size of the field.

An existing parcel maps at scale 1:100000 and 1:25000, received from LMA (Land Management Agency) have been used for inventory of crop parcels. The maps guided by local agronomists were old (1986-1989) and should be renewed. For all soums have been produced:

Parcel map by crop type
Registration map by users
Parcel boundary map

A ground survey had been in the period from 24th of August to 5th of September, 2000. The scope of these visits are the collection of ground observations for photo-interpretation and image classification result, and also parcel information by interviewing the agronomists that are responsible for statistics at soum level.

Comparison of Parcel Acreages
Parcel area calculation differences between statistical data and calculated by GIS environment are shown by charts. Totally 1857 amount of field was identified in image with total area 224076 ha of which 85976 ha sown area, 65050 ha fallow and 71223 ha non-cultivated land. On 2049 ha of field area we haven’t statistical data (by agronomist data).

The data recorded from agronomists and imagery is very close while the difference between official statistics and these data are quite big.

Conclusion
The usefulness of remotely sensed data particularly the Landsat ETM data in conjunction with relevant GIS data and field information has dispensed an important source of information in the assessment and monitoring of crop at the regional level.

As shifting cultivation continues to play a dominant role in pasture degradation from grazing area to dry vegetation and eroded area, forest conservation and agricultural development. Due to economic condition cultivated crop land is decreased, due to market economy and mining area is increased and it is influenced to the land to be come eroded.

Field sizes are large (150-350 ha) and the investigation of cultivated land, mainly wheat, with distinct spectral appearance possibly derived from high resolution data. Remotely sensed data should be confirmed by intensive ground survey.

Inventory of arable and abandoned land and determine the real parcel size is possible. The comparison area results (image data and official statistics) of parcels for 7 soums shows that the methodology of inventory and registration of crop land should be changed and renewed.

References

“Observing and analyzing natural resources” Spot Image, Journal, CNES, France, 1998
“Multispectral Imagery reference guide” Spectral Imagery Training Center, LOGICON Geodynamics, Inc. Fairfax, Virginia, USA, 1997
“Report of Antjie” ISEAM Tacis expert, Ulaanbaatar, 2000
“Report of Fabrizio” ISEAM Tacis expert, Ulaanbaatar, 2000
“National Atlas of Mongolia” Academy of Science Mongolia, Ulaanbaatar, 1990
“Land Cover Assessment and Monitoring” UNEP, Bangkok, 1995
“Asian – Pacific Remote Sensing and GIS Journal” Volume 10, ESCAP, 1998