This study analyzed land degradation of irrigated cropland in northern Uzbekistan using satellite remote sensing at multiple scales. At the regional scale, 23% (94,835 ha) of irrigated cropland showed degradation trends over time. Finer scale mapping using Landsat imagery found 18% (52,938 ha) of fields had decreased vegetation cover between 1998 and 2009, including 17% that became fallow. The results were 93% consistent between scales and can inform policies for rehabilitating degraded fields through sustainable land use practices. Further validation is needed to refine the approaches.

1. Opportunities for climate change
adaptation through afforestation
of degraded croplands
in Central Asia
Olena Dubovyk
Multi-scale targeting of land
degradation in northern Uzbekistan
using satellite remote sensing

2. 2
Irrigated areas of Central Asia
World Bank (2003)

3. Study area
Area: 662,042 ha
Population: 2 million
Main activity: irrigated agriculture
Irrigated cropland: 410,000 ha
 Arid continental climate: annual
rainfall ~100 mm; PET ~1400 mm yr-1
 Up to 90% (min 50%) of land is
allocated to the state order crops (cotton
and winter wheat)
3
Dubovyk et al. (2013a), Erdkunde

4. 4
 Natural and secondary soil
salinization
 Shallow saline groundwater
tables
 Poor drainage
Some land is abandoned but
most is still cropped
No spatial information is
available
Degraded irrigated cropland
Abandoned cropland, Southern KarakalpakstanAbandoned highly saline cropland, Southern KarakalpakstanAbandoned highly saline cropland, Khorezm

5. Objectives
Overall objective
to enhance spatial knowledge on the cropland degradation in the irrigated
agro-ecosystems to support policy interventions on land rehabilitation
measures
6
Degradation of irrigated cropland
Vegetation loss over time, irrespective of whether caused by worsening soil
quality or decreased cultivation, denotes a decline in economic productivity
of irrigated cropland and can be considered as degradation of its productive
function.
1: To analyze extent and factors of irrigated cropland degradation at the
regional scaleMap LD
Map degraded
fields
2: To derive parcel-specific information on irrigated cropland degradation
Dubovyk et al. (2013c), Quaternary International

6. Mapping LD at different spatial scales
7
Map LD
trends
Map degraded
fields

7. 8
Dubovyk et al. (2013b): Environmental Monitoring and Assessment
Mapping LD at regional scaleMap LD
Affected area:
23% (94,835 ha)

8. 9
Mapping LD at local scale (1)
Object-based change map based on change vector analysis (CVA) and fraction images
calculated from multitemporal Landsat TM (1998 and 2009)
Dubovyk et al. (2013c), Quaternary International
Map degraded
fields

9. 10
-Fallow in 1998 and in 2009: 17% (29,029
ha)
-Cropped in 1998 and fallow in 2009: 20%
(11,064 ha)
Dubovyk et al. (2013c), Quaternary International
Mapping LD at local scale (2)Map degraded
fields
29
3 4
5
38
21
0
5
10
15
20
25
30
35
40
45
Cotton Winter
wheat
Rice Wheat -
summer
crop
Fallow land Other crops
%ofvegetationcoverdecrease
Distribution of vegetation cover decrease in relation
to agricultural land use in 2009
Affected area:
18% (52,938 ha)

10. 11
Discussion
 Vegetation decrease does not always imply LD
Comparison between the 30m Landsat-based maps and 250m MODIS-
based revealed overall correspondence of 93%
Compared to the result of the MODIS-based trend analysis, the result of
the Landsat-based bi-temporal change detection underestimated the
vegetation cover decrease (omission error is 43%)
Further on-site validation is needed
Map LD Map degraded
fields

11. 15
Conclusions (1)
MODIS-based LD trend map reveals the LD on 94,835 ha;
the produced map is valid (PCP=68%)
 Landsat-based change map highlights vegetation cover
decline areas at field level and is comparable with the
MODIS-based map (overall agreement=93%)
This study contributes to the development of methods that will support LD
assessments in similar environments using satellite remote sensing
This research provides multi-scale spatial information on LD in northern
Uzbekistan
This study contributes to the development of methods that
will support LD assessments in similar environments using
satellite remote sensing

12. 16
The generated spatial information and insights on its implications is now available
for planning sustainable land use options and land rehabilitation measures
Results are used for institutuional and policy analysis to generate policy
recommendations on rehabilitation of the degraded cropland
Operational cropland degradation monitoring at different spatial scales using
freely available satellite imagery (i.e., MODIS and Landsat)
From the technical side, the approaches developed at the regional and local scales
require further validation, e.g. fusion of satellite and in situ datasets
From the application side, further refinement should be done in close cooperation
with local players to assure applicability of the results
Towards an integrated assessment of land degradation
Research implications
Conclusions (2)

13. Thank you!