The identification of the study area was made on the basis of different topographic maps (Table 1) printed at the beginning and the mid 80’s by the Cartographic division of Rabat. In particular the topographic map on the scale of 1:50,000 and 1:100,000 were available. For the thematic map only the geological and the pedological ones were available. The first one, on the scale of 1:100,000, was printed by the Ministere de l’Energie et des mines-Direction de la Geologie in 1987. The second one, on the scale of 1:200,000, is included in the work of Ghanem (1981) that describes the soils of the region of Zaers in Basse-Chaouia and of Sehouls (atlantic Moroccan meseta).
|
Scale |
Name |
|
1:50,000 1:100,000 |
Ben Slimane, Sidi Bettache, Sidi Zemmouri, and Mohammedia Al Gara, Rommani, El Gara, and Zhiliga |
Table 1 - Topographic map data sets
For the remote sensing data, satellite images and aerial photographs were utilised. Unfortunately the latter covered only the northern part of the study area so for the southern part all the interpretation was carried out through satellite images. The Table 2 summarises the principal characteristics for the two different data sets.
|
Aerial photos |
||
|
Type |
Date of acquisition |
Scale |
|
Panchromatic |
October 1982 |
Approx. 1:17,000 |
|
Satellite images |
||
|
Satellite – Sensor |
Date of acquisition |
Bands |
|
Landsat-5 TM |
07/27/1985 |
1, 2, 3, 4, 5, 6, and 7 |
|
Landsat-7 ETM+ |
01/02/2000 |
1, 2, 3, 4, 5, 6, 7, and pan |
|
Landsat-7 ETM+ |
04/23/2000 |
1, 2, 3, 4, 5, 6, 7, and pan |
|
Landsat-7 ETM+ |
08/13/2000 |
1, 2, 3, 4, 5, 6, 7, and pan |
Table 2 - Remote sensing data sets
Different types of Landsat satellite data were purchased to have a better overview. The data recorded 15 years before allowed us to analyse vegetation changes of the study area.
The utilisation of Landsat-7 data allowed us to evaluate the utility of these new data for the natural resources study. The Landsat-7 was launched on April 15th 1999 and its new characteristic is the presence of the sensor Enhanced Thematic Mapper Plus (ETM+). This last one, with respect to the one onboard of the previous Landsat 5, has two particularities (Table 3): the presence of the additional panchromatic band and the higher spectral resolution of the thermal band (60m against the previous 120m).
|
Band |
Wavelength band (m m) |
Resolution (m) |
|
1 (B) |
0.45-0.52 |
30 |
|
2 (G) |
0.52-0.60 |
30 |
|
3 (R) |
0.63-0.69 |
30 |
|
4 (NIR) |
0.76-0.90 |
30 |
|
5 (MIR) |
1.55-1.75 |
30 |
|
6 (TIR) |
10.4-12.5 |
60 |
|
7 (MIR) |
2.08-2.35 |
30 |
|
8 (PAN) |
0.50-0.90 |
15 |
Table 3 - The spectral characteristics of Landsat 7 - ETM+