Image Processing Reference
In-Depth Information
Data Analysis : For each city, we performed the following operations: (1) land use
mapping using ancillary data and GIS for digitizing of city maps at a scale of
1:10,000 from the1970s; (2) pre-processing of two panchromatic Spot-HRV imag-
ery, which consisted of image subsetting, geometric correction according to the
parameters of the national reference system (Clarck's 1880 projection and Merchich
Datum); (3) land use mapping based on visual interpretation, using two panchro-
matic Spot-HRV imagery acquired during the last 2 decades; and (4) analysis and
interpretation of the three land use maps, using GIS for analyzing the changes of
land uses and modeling their mutual impacts.
Results and Discussion : The results and findings of the case study in Morocco
included detailed land use maps, at a scale 1:50,000. These maps offered an exten-
sive diagnosis of land use categories in terms of areas that were developed during
each decade (1970s, 1980s and 1990s) (Anys et al. 1999a, b ; Ait Belaid 2003 ). The
adopted typology included eight thematic classes, namely: urban areas, rural settle-
ments, fruit trees, rain-fed crops, irrigated crops, rangelands, forests and water
bodies. The total area of each site is 90,000 ha.
Evolution maps for three intervals of time (1970-1980, 1980-1990 and 1970-1990)
revealed the temporal evolution and trends of land use categories in the study sites.
In 20 years, the area of urban areas increased by 598 ha (344%) in the city of Ksar
El Kébir (Fig. 13.4 ), and by 981 ha (180%) in Béni Mellal, while the area of rural
settlements increased by 1,945 ha (160%) in Ksar El Kébir and 756 ha (200%) in
Béni Mellal. For the city of Khémisset (for which there was no city map available
for the 1970s), the 10 years extension was 648 ha (70%) for urban areas and 363
ha (60%) for rural settlements. It is noticed that most urban changes occurred dur-
ing the 1980s, compared to the 1970s.
The evolution matrix generated for the city of Ksar El Kébir, for the whole inter-
val 1975-1996 signals the major land use changes that occurred (Table 13.1 ).
Furthermore, it quantitatively illustrates the land use categories, which are impacted
by any change and vise-versa. The zero value in the matrix implies no land use change
in corresponding classes. During the period 1975-1996, urban areas expanded 598
ha, of which 501 ha were converted from rain-fed crops, 62 ha from rural settle-
ments and 19 ha from fruit trees. The area of rural settlements increased tremen-
dously by 1,945 ha, of which 1,372 ha were taken from rain-fed crops, 520 ha from
rangelands and 61 ha from fruit trees. In sum, urban growth and rural settlements
were severely impacting agricultural lands (rain-fed crops, fruit trees, rangelands).
We can notice as well the increase of the area of water bodies by 1,457 ha, and the
area of irrigated crops by 12,917 ha, which correspond respectively to the construc-
tion of a new dam and the development of a new irrigation plan in the region
between 1970 and 1980.
The cartographical and statistical results are powerful tools for depicting the
areas of agricultural lands that need to be protected. Furthermore, these results
generated from this analysis were used to inform the master plan of urban planning
(Urban Planning Director Scheme). The cost of the study estimated at US$18/km 2 .
The duration of this analysis was 8 months. Given the scale of the analysis conducted,
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