Abstract form

Large-scale mapping of solonetzic complexes in the Northern Caspian
Lowland using automated interpretation of Quickbird images
Mariya V. KONYUSHKOVA
V.V. Dokuchaev Soil Science Institute, Russian Academy of Agricultural Sciences,
Pyzhevskiy per. 7/2, Moscow, 119017 Russia
Contact e-mail: mkon@inbox.ru
The goal of this study was to develop a procedure for large-scale mapping of solonetzic
complexes using automated interpretation of very-high-resolution space-borne images.
Solonetzic complexes are widespread in the northern part of the Caspian Lowland. They
include the soils with different degrees of salinization: strongly saline Solonetzes (SN),
slightly saline light chestnut soils (Kastanozems, KS) and nonsaline Chernozem-like
(CL) soils replacing one another at distances of about 5–30 m. Dark-coloured CL
occupy microlows with a relative depth of 10–30 cm, SN occur on microhighs, and KS
occupy slopes. The portion of SN in the soil complexes varies from 25 to 75%.
Earlier, large-scale soil maps of solonetzic complexes were developed on the basis of
detailed surveys at key plots with a further extrapolation of the obtained data. The
reliability of such extrapolation is low, because the proportions between different soils
in the complexes may change considerably at distances of about 500 m. High-resolution
(30%
of CL were identified. In group 1, the portions of KS and CL were interrelated: K1(%)
= –4.17CL(%) + 86.8 (R 2 =0.94). In group 2, the area of K1 is about 20% (15–25%).
III. These regularities were used to develop the soil map of the test polygon (scale
1:25000) with the following mapping units (solonetzic complexes): (1) CL 0-5%, КS
70-80%, SN 20-30%; (2) CL 5-10%, KS 50-70%, SN 30-40%; (3) CL 10-15%, KS 35-
50%, CN 40-50%; (4) CL 15-30%, KS 15-25%, SN 50-75%.
Thus, this method ensured an automated delineation of the areas with CL with high
(90%) reliability, on the basis of statistically reliable (R 2 =0.94) relationships, the
portions of SN and KS were determined in each mapping area. This study was
supported by the Russian Foundation for Basic Research, project no. 07-04-00136a).
Key words: Solonetzic soil complexes, Caspian Lowland, Quickbird imagery, image
interpretation, large-scale soil mapping.
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