=Paper=
{{Paper
|id=Vol-1152/paper70
|storemode=property
|title=Land Use Change Analysis for Assessment of Soil Protection Efficiency In Urban Area - URBAN SMS Project
|pdfUrl=https://ceur-ws.org/Vol-1152/paper70.pdf
|volume=Vol-1152
|dblpUrl=https://dblp.org/rec/conf/haicta/GluszynskaSZL11
}}
==Land Use Change Analysis for Assessment of Soil Protection Efficiency In Urban Area - URBAN SMS Project==
https://ceur-ws.org/Vol-1152/paper70.pdf
Land use change analysis for assessment of soil
protection efficiency in urban area – URBAN SMS
project
Magdalena Gluszynska1, Grzegorz Siebielec1, Anna Zurek1, Artur
Lopatka1
1
Department of Soil Science Erosion and Land Protection, Institute of Soil Science and Plant
Cultivation, Pulawy, Poland, e-mail: gs@iung.pulawy.pl
Abstract. The objective of the presented work was to conduct an ex-post
analysis of land use change in Wroclaw city, Poland, as a response to the soil
protection regulations. The assessment that was a part of Urban Soil
Management Strategy (URBAN-SMS) project involved development of land
use change maps based on the satellite image data, analysis of land use change
trends within 15 years period and subsequent assessment of valuable soils’
consumption for urban expansion as an indicator of soil protection efficiency.
Most of new transitions into sealed area took place on arable and semi-natural
lands. Despite the fee payment instrument, existing within the period under
analysis, the most valuable soils were not sufficiently protected. It can be
partly explained by the spatial distribution of the best soils.
Keywords: land use, satellite image, soil sealing, soil protection
1. Introduction
Urbanization can be considered as a pressure on landscape reducing its
buffering capacity and resistance to degradation (Antrop, 2004). Evaluation of these
pressures is fundamental for development of strategies for protection of soils and soil
functions. Sealing is one of threats for agricultural soils identified in the framework
of Strategy for Soil Protection (COM231, 2006). The sealing process may limit
performance of soil functions (retention, production, filtering, biodiversity, etc.) and
accelerate other soil threats such as decline in organic matter, contamination, floods,
compaction (Stuczynski, 2007). There is increasing interest in determining or
modeling the land use change magnitude and its environmental consequences
(Pauleit et al., 2005; Rounsevell et al., 2006; Veerburg et al., 2006; Stathis et al.,
2010).
The objective of the presented work was to conduct an ex-post analysis of
land use change in Wroclaw city, Poland, as a response to the soil protection
regulations. It is essential to understand what is the rate and pattern of changes in
land use and how these changes, especially soil sealing, affect the overall
_______________________________
Copyright ©by the paper’s authors. Copying permitted only for private and academic purposes.
In: M. Salampasis, A. Matopoulos (eds.): Proceedings of the International Conference on Information
and Communication Technologies
for Sustainable Agri-production and Environment (HAICTA 2011), Skiathos, 8-11 September, 2011.
787
performance of the soil function within the city area. Such an analysis is thought to
raise awareness on trends of soil consumption within urban development process and
provide information on effectiveness of the soil protection measures. It must be noted
that soils differ in properties and, thus, ability to fulfill such functions as retention,
biodiversity, filtering, crop productivity.
2. Methodology and Data
The conceptual framework of the analysis of loss of high quality soils in the
test area is presented in Figure 1. It involved development of land use change maps
based on the satellite image data, analysis of land use change trends within 15 years
period and subsequent assessment of valuable soils’ consumption for urban
expansion as an indicator of soil protection efficiency.
Figure 1. The concept of soil protection efficiency analysis in test areas
2.1. Satellite Images
Satellite images of 10-meter resolution were gathered from SPOT databases.
The images represented two periods in order to study land use changes within 15
year timeframe – the black/white photo was captured in 1991 whereas the color
photo was taken in 2006 period. The B&W SPOT image is monospectral, color
photo is a combination of 4 bands of different wavelengths (0.5-0.59, 0.61-0.68,
0,78-0.89, 1.58-1.75 µm).
2.2. Soil Map
Soil–agricultural map of Wroclaw region in scale 1:25000 was used for
Wroclaw case study. Soil valorization system in Poland involves soil suitability units
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at the range 1-14 for arable lands and 1z-3z for grasslands. This classification
basically reflects productivity potential of the soil (suitability to produce certain
crops) and the units were delineated based on various soil properties as well as
climatic conditions, water conditions and slope. The soil suitability units generally
well describe other soil functions such as water retention, buffering capacity or
biodiversity. The classes were grouped into high, medium and low quality soils
(either from perspective of production function, ecosystem function, buffering,
retention etc.). Units 1, 2, 4, 1z were classified as high quality soils, units 3, 5, 8, 2z
as medium, while units 6, 7, 9, 14, 3z and barren lands as low quality soils.
2.3. Land Use Change Analysis
Land use maps of 10-meter resolution were produced for the two periods
through classification of the satellite images (Fig.2) in Definiens Professional
software. Process of land use map development in this software basically consists
with two major steps: segmentation and classification. The satellite image is
represented by 10mx10m pixels described by spectral information (reflectance data
at various wavelengths). Segmentation phase is a process based the fact that land use
types (e.g. built up area, forest, water) posses different spectral information.
Segmentation delineates spectrally homogenous areas – the segmentation algorithms
are used to subdivide the entire image represented by the pixel level domain or
specific image objects from other domains into smaller image objects (groups of
pixels).
Figure 2. The SPOT satellite image used for development of land use maps.
The classification is a procedure that associates image objects with an
appropriate land use class labeled by a name and a color. After careful manual
revision of the classification using all available spatial information the obtained final
layers were used as land use maps of the pilot area (Fig. 3).
The land use maps contained 13 different land use types: continuous residential
areas; commercial and industrial areas; green recreation areas (parks); airports; sport
and leisure facilities (with generally impermeable or reconstructed surfaces with
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limited performance of soil functions – e.g. stadiums, tennis courts); dump and
mineral extraction sites; arable lands; grasslands (pastures and meadows); forests;
semi-natural areas (covered by shrubs, trees, not used by agriculture); discontinuous
residential areas (residential area with dispersed buildings, still can fulfill some soil
functions since most of surface is unsealed); water bodies; transport facilities.
The land use change information for the analyzed area was produced through
comparison of land use layers derived for different periods.
Figure 3. Land use map of Wroclaw for 2006
2.4. Approach for Analysis of Soil Protection Efficiency
The information on land use change was superimposed on the map
characterizing soil quality in order to detect to what extend the urbanization took
place on valuable soils. The new sealed area, reflecting the built up sprawl of last 15
years, consisted with expansion of the following land use classes: continuous
residential area, commercial/industrial area and transport facilities. The soils under
these new land use types fully lost their environmental functions.
In order to assess what is the scale of consuming valuable soils by urban
sprawl, the transition index was used. It reflects the intensity of land use flows in the
context of soil quality [Stuczynski, 2007].
Transition index (TI) = percent of soil class “n” in new built area/percent of
soil class “n” in whole soil area
790
Looking at land use stocks and flows occurring on soils belonging to
different quality classes, it is difficult to make a straightforward assessment whether
the observed land use change is equally distributed among soil quality classes since
the contribution of e.g. soils of high productivity or high water retention potential to
the total soil cover may vary greatly between regions or parts of the city (Stuczynski,
2007). Therefore the size (measured in hectares) of change on soils of certain
characteristics is not a good indicator if these soils are preferentially taken by
urbanization.
Interpreting the transition index is straightforward – for example, index
value of 2 for a flow on a given soil class (e.g. high quality soils) means that within
changed land the share of this class is twice as high as in the entire soil cover,
therefore the intensity of high quality soils consumption is much larger than can be
expected from a structural pattern of soil quality.
3. Results and Discussion
Continuous urban fabrics cover 35 % of total area of the city and
surroundings enclosed in Wroclaw LAU-2 region. Areas able to fulfill soil functions
other than surface for construction consist with arable lands, semi-naturally covered
lands, grasslands and forests – their share in total area is 22, 14.5, 11 and 7.7 %,
respectively, which together exceeds 55% of total area (Table 1).
Table 1. Summary of land use changes in Wroclaw between 1991 and 2006
Land use class area in 2006 area in 1991 difference
% of % of
[ha] total [ha] total [ha] %
continuous residential areas 5697.6 19.8 5322.2 18.5 375.4 7.1
commercial and industrial areas 2093.9 7.3 1946.3 6.8 147.6 7.6
green urban areas 697.7 2.4 697.7 2.4 0.0 0.0
airports 237.8 0.8 237.8 0.8 0.0 0.0
sports and leisure facilities 228.0 0.8 228.0 0.8 0.0 0.0
dump/mineral extraction sites 34.4 0.1 34.4 0.1 0.0 0.0
arable land 6406.4 22.3 6619.4 23.1 -212.9 -3.2
grasslands 3145.0 11.0 3242.4 11.3 -97.4 -3.0
forest 2207.4 7.7 2207.4 7.7 0.0 0.0
seminatural 4163.0 14.5 4387.3 15.3 -224.3 -5.1
discontinuos residential areas 1777.7 6.2 1781.8 6.2 -4.1 -0.2
water bodies 767.1 2.7 751.4 2.6 15.7 2.1
transport facilities 1248.6 4.3 1248.6 4.3 0.0 0.0
total area 28704.8 x 28704.8 x x x
791
The area of continuous sealed surfaces increased by over 500 hectares
within the period of interest. Most of this change can be referred to residential areas.
Discontinuous residential zones did not expand recently - they cover approximately 6
% of total area. Such areas with dispersed pattern of buildings may perform soil
functions in certain extend due to substantial share of uncovered surfaces and
undisturbed soil profiles.
The distribution of new sealed surfaces over soil quality classes are
presented on Figure 4. The statistics of soil consumption for urbanization indicate
preferential use of high quality soils in Wroclaw (TI>1.3, 3.6% of high quality soils
consumed). Share of the weakest soils in newly sealed area was much smaller than
their share in total resources despite that their supply is substantial (Table 2).
Figure 4. Urban sprawl in Wroclaw between 1991 and 2006 on soil quality map
The land use change data provided here may be somewhat different from the
official statistics that use different methodologies, however the assessed level of the
change of agricultural lands into sealed area was sufficiently precise as confirmed by
the city administration. Our study utilized satellite images for detection of land use
changes – such a method is burdened with a dose of uncertainty. However the
792
advantage of the applied approach is that it enables analysis of spatial trends of land
use change and their linkage to soil quality information.
Table 2. Indexes for transition of soils of different quality into sealed area for
Wroclaw
soil quality class Area of Share of Area Percent transition
soil class soil class converted converted index (TI)
(ha) in total (ha) [% of soil
area [%] class area]
high quality 7377 48.6 266 3.6 1.33
medium quality 2259 14.9 42 1.8 0.68
low quality 5547 36.5 105 1.9 0.69
The expansion of artificial surfaces took place equally on arable and semi-natural
lands. New artificial surfaces mostly comprised with residential fabrics to fulfill
demand for inadequate housing provision. The analysis fills the information gap on
the quality of soils lost in urbanization process and, thus, efficiency of soil protection
approaches.
It is evident in the light of this study that the best soils were not efficiently
protected in Wroclaw. It is assumed that the regulations present in Slovakia help to
protect the most valuable soils. The soils classified as high quality had been covered
by the fee payment. Transformation of these agricultural lands into other purposes
was loaded with obligatory payment with a range of payment from approx. 6 to 10
EUR per square meter, depending on the soil class. Additionally, each transformation
of agricultural soils of best classes into non-agricultural use must have been approved
by the Ministry of Agriculture if the area exceeded 0.5 ha. The collected fees fully
supply the Fund of Land Protection that is spent for land protection, recultivation and
improving soil quality (e.g. liming). This regulation had covered all soils until 2008,
after this date the urban soils have been excluded from this instrument. The described
practice did not ensure the efficient protection of most valuable soils in Wroclaw.
4. Conclusions
Combination of satellite image based land use change maps and soil maps
provided valuable information on trends in soil cover management under
urbanization pressure. The assessment performed for Wroclaw revealed negative
trend of preferential use of the most valuable soils.
Most of new urban sprawl took place on arable and semi-natural lands.
Despite the fee payment instrument, existing within the period under analysis, the
best performing soils were not sufficiently protected. It can be partly explained by
the spatial distribution of the most valuable soils and still limited establishment of the
soil issues in the law regulating land management.
Acknowledgments. The presented work was performed within Urban Soil
Management Strategy project funded by the CENTRAL EUROPE programme
793
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