Status of Land Use Land Cover of Sheka zone during Study Years
Using Satellite Remote Sensing and Geographic Information System, this research work analyzes the land use and land cover change dynamics in the Sheka zone southwestern Ethiopia. The four images were taken from the Multi-temporal Landsat imageries of TM (1985, 1995) and ETM+ (2005, 2015). All images were geo-referenced and images classification was prepared by using the maximum likelihood classifier algorithm. In Sheka zone, Masha and Anderacha woreda four major land cover classes were identified in each date of the satellite image. The land cover classes and coverage in each date of the image are given below (table 4).
Conversion of dense forests to other forms of land use has been the general trend in Sheka zone Masha and Anderacha woreda. Such changes have been broad in the previous quite a few years in the Sheka forest.(MELCA Mahiber, 2007). The fast extension of investment agriculture and the declining of traditional forest conservation culture in the study area have required this sort of change. The same trend has been observed in the Masha and Anderacha woreda in the Sheka zone.
The present examination was expected to dissect the nature and degree of land use/ land-cover changes in Masha and Anderacha woreda since most recent three decades and recognize the fundamental powers behind them. The land use/ land-cover changes statistics of 1985 and 2015 and the change and growth in areal degree in various land use/ land-cover changes between the three times periods in Sheka zone Masha and Anderacha woreda are given in (Table 5 and Figure 5).
The study area has been divided into the four major land use/ land-cover classes as shown in (Table 5). The forest of Sheka in Masha and Anderacha woreda in Sheka zone is the main natural resource. Most of the forestlands are reserved by traditional forest conservation cultures like DEDO, GUDO, and KOBO. Nevertheless, gradually, the dense forest is being lost to open forest, agricultural land, and settlements.
Table 3 :Summary of LULC Class Statistics of 1985, 1995, 2005 & 2015
Land use
|
Land cover in each year of image
|
1985
|
1995
|
2005
|
2015
|
(sq.-km)
|
(%)
|
(sq.-km)
|
(%)
|
(sq.-km)
|
(%)
|
(sq.-km)
|
(%)
|
Dense forest
|
912
|
57.35%
|
824
|
51.82%
|
790
|
49.68%
|
514
|
32.32%
|
Open forest
|
437
|
27.48%
|
469
|
29.49.2%
|
470
|
29.55%
|
480
|
30.18%
|
Agriculture
|
233
|
14.65%
|
284
|
17.86%
|
316
|
19.87%
|
572
|
35.97%
|
Settlement
|
7
|
0.44%
|
13
|
0.81%
|
14
|
0.88%
|
23
|
1.44%
|
Each land use land cover map has been classified into four classifications which are the dense forest, open forest, agricultural land, and settlement see table (Table 5). The land use land cover map of 1985 is considered as the baseline or zero change of the study. The land use land cover classification of 1985 is shown on the map (Figure 6). This research work tried to show the current land use land cover situation in Sheka zone Masha and Anderacha woreda from the period 1985 to 2015. The result of the study showed that significant conversion of one land uses land cover to the other land cover class. Farming area and the open forest has been extending and exceedingly ruling different classes. It is a result of the addition of the populace and the presentation of estate farming in the examination territory.
Only about 14.65% of the land was used for agriculture in Sheka zone Masha and Anderacha woreda by the year 1985, while the other land cover classes that are a dense forest, open forest and settlement covered the remaining 84%. In the year, 2015 agricultural land dominates the other land cover classes. For example, agricultural land in the year 1995 has increased by about 3.21% in 10 years gap. While open forest has shown 2% increment and settlement are increasing only by 0.37%. In reverse to this, dense forest decreased by 5.53% in the same year. In the successive period i.e. 1995–2005, agricultural land has shown an increase of about 2.01% while, open forest and settlement have shown very little increment it is only by 0.06 % and 0.07% respectively.
In 1985 as it is illustrated in land use land cover map (Fig. 6), it was on the northern, southern and western part of the study area where the dense forest was concentrated while open forest and agricultural land were most abundant at the central part of the study area. But as time goes on agricultural land and open forest expand toward the northern, southern and western part of the study area and then after 2015 the majority of the land come under agricultural land followed by open forest. Very small part of the study area now under dense forest.
ENVI 5.0 and ERDAS 2015 change detection statistics show that 57.35% dense forest of the 1985 land use land cover was reduced to 32.32% thus there was a 25.03% loss of dense forest cover from the 1985s to 2015 which was mainly associated with the conversion of dense forest to other land cover class in the study area see table 5. In 1995, it was observed that 912 sq. Km dense forest was cleared and reduced to 824 sq. Km that resulted in 5.53% decrement of dense forest.
The study area has four land use land cover categories, which were dense forest, open forest, agricultural land, and settlement. The description of these land cover categories was presented previously (Table 5).
Table 4 : the spatial extent of various land-use and land cover categories during 1985
|
Area (sq.-km)
|
Percent Area (%)
|
Dense forest
|
912
|
57.35
|
Open forest
|
437
|
27.48
|
Agricultural land
|
233
|
14.65
|
Settlement
|
7
|
0.44
|
Total
|
1590
|
100
|
The satellite image of 1986 was classified based on reflectance signature of solar radiation that differs according to various Earth surface objects. The land use land cover classification for 1985 from TM satellite image (Figure 6) showed that dense forest and open forest accounted for 912 sq. km (57.35%) and 437 sq. km (27.48 %) respectively, while agricultural land and settlement amounted to about 233 sq. km (14.65%) and 7 sq. km (0.44%) respectively (Table 6). Most segment of the land use land cover class was thick forest amid this period.
The land use land cover classification for 1995 from TM+ satellite image (fig 7) showed that dense forest and open forest accounting for 824 sq. km (51.82%) and 469 sq. km (29.49%) respectively, while agricultural land and settlement amounted to about 284 sq. km (17.86%), 13 sq. km (0.81%) respectively.
Table 5: the spatial extent of various land-use and land cover categories during 1995
|
Area (sq.-km)
|
Percent Area (%)
|
Dense forest
|
824
|
51.82
|
Open forest
|
469
|
29.49
|
Agricultural land
|
284
|
17.86
|
Settlement
|
13
|
0.81
|
Total
|
1590
|
100
|
The land use land cover classification for 2005 from ETM+ satellite image (figure xxx) showed that dense forest and open forest accounting for 790 sq. km (49.68%) and 470 sq. km (29.55%) respectively, while agricultural land and settlement amounted to about 316 sq. km (19.87%), 14 sq. km (0.88%) respectively.
Table 6: the spatial extent of various land-use and land cover categories during 2005
|
Area (sq.-km)
|
Percent Area (%)
|
Dense forest
|
790
|
49.68
|
Open forest
|
470
|
29.55
|
Agricultural land
|
316
|
19.87
|
Settlement
|
14
|
0.88
|
Total
|
1590
|
100
|
The land use land cover classification for 2015 from ETM+ satellite image (figure xxx) showed that dense forest and open forest accounting for 514 sq. km (32.32%) and 480 sq. km (30.18%) respectively, while agricultural land and settlement amounted to about 572 sq. km (35.97%), 23 sq. km (1.44%) respectively.
Table 7: the spatial extent of various land-use and land cover categories during 2015
|
Area (sq.-km)
|
Percent Area (%)
|
Dense forest
|
514
|
32.32
|
Open forest
|
480
|
30.18
|
Agricultural land
|
572
|
35.97
|
Settlement
|
23
|
1.44
|
Total
|
1590
|
100
|
Classification Accuracy Assessment
This appraisal is completed to assess the classification efficiency of the ERDAS IMAGINE 2015 software programming in order to speak to the present land use /cover map of the investigation territory. The procedure had decided how adequately pixels were assembled into the right component classes under scrutiny. It is expert the characterized image with the ground by the assistance of field survey or reference map. To evaluate the productivity of classification precision, a confusion matrix was developed.
To conduct this assessment 100 random points were decided to be collected using thump rule; states that 30 points for each land use land cover class and the image were containing four classes. The overall accuracy for the four-time period of classification results 86% and accuracy of each Land Use Land Cover classes are present in the table below.
Table 8: LULC confusion matrix.
Land use land cover class
|
Dense forest
|
Open forest
|
Agricultural land
|
Settlement
|
Dense forest
|
89
|
8
|
3
|
0
|
Open forest
|
8
|
87
|
9
|
3
|
Agricultural land
|
2
|
5
|
88
|
8
|
Settlement
|
1
|
0
|
0
|
89
|
Total
|
100
|
100
|
100
|
100
|
Land Use Land Cover Change Detection Scenarios
A change analysis for the study period was performed in the ERDAS IMAGINE 2015 software to prepare a change detection map. The use/land cover categories delineated from the Multi-temporal Landsat imageries of TM (1985, 1995), ETM+ (2005, 2015) data were an overlay, and the transformation of land-use and land-cover classes from one to another was observed. The spatial extent of various land /land cover statistics of the changes in land use/ land cover categories over the period from 1985 to 2015 was generated.
During the period 1985 to 2015 spanning over four decades, there have been remarkable changes in dense forest, open forest, and agricultural land. The agricultural land has expanded from 14.65% in 1985 to 35.97% in the year 2015. Conversely, the dense forest has shrunken from (57.35% in 1985 to 32.32% in 2015). A similar trend has been observed in open land and settlement which has increased from 27.48% in 1985 to 30.18% in 2015 and in 1985 0.44% to 1.44% 2015 (Tables 11 & 12).
Table 9: the spatial extent of various land-use and land cover categories during 1985
|
Area (sq.-km)
|
Percent Area (%)
|
Dense forest
|
912
|
57.35
|
Open forest
|
437
|
27.48
|
agriculture
|
233
|
14.65
|
Settlement
|
7
|
0.44
|
Total
|
1590
|
100
|
Table 10: the spatial extent of various land-use and land cover categories during 2015
|
Area (sq.-km)
|
Percent Area (%)
|
Dense forest
|
514
|
32.32
|
Open forest
|
480
|
30.18
|
agriculture
|
572
|
35.97
|
Settlement
|
23
|
1.44
|
Total
|
1590
|
100
|
Land Use Land Cover Change Transition Matrix between the Years
Land Use Land Cover Change Transition Matrix from 1985 – 1995
Total percentage growth in different LULC categories in the study area is very high. Some LULC classes have registered a growth while others have witnessed a negative growth as shown in (Table 13 and Figure 12). The dense forest has reduced from 57.35% in 1985 to 51.82% in 1995 thus registering a decrement in growth by 5.53%. Deforestation, expansion of agricultural land and increasing settlement are putting massive weight on the woodland assets of the investigation zone.
Since the area is very rich in cash crops like coffee and timber, it has attracted many migrants from distance and neighboring this coupled with the rapid rate of urbanization in the study area has brought about the speeding up in the deforestation procedure. Open forest cover is one of the major land-cover categories in the Masha and Anderacha woreda in the Sheka zone and has registered a further growth of 27.48% from 1985 to 29.49.2percentage 1995. The degradation of forests because of different reasons over a significant lot of time changes them into other land use land cover class. In the study area agricultural land has registered a significant increase from 14.65% (233 Sq. Km) in 1985 to 17.86% (284 Sq. Km) in 1995, therefore, showing an absolute change of -3.21% that is, -51 Sq. Km at an annual rate of -0.32%.
Most of the settlement area has shown a significant increase as compared to other class in the Masha and Anderacha woreda of the Sheka zone. From 0.44% (7 Sq. Km) in 1985 to 0.81% (13 Sq. Km) in 1995, therefore, showing an absolute change of 0.37% that is, 6 Sq. Km. Population increase and rapid rate of urbanization are responsible for the expansion of settlement in the study area.
Table 11: Land Use Land Cover Change Transition Matrix from 1985 – 1995
|
The area in 1985 (Sq. Km)
|
(%) Land Cover in 1985
|
The area in 1995 (Sq. Km)
|
(%) Land Cover in 1995
|
Change between
1985 and 1995
|
|
|
|
|
|
|
The area in Sq. Km
|
%
|
Dense forest
|
912
|
57.35
|
824
|
51.82
|
-88
|
-5.53
|
Open forest
|
437
|
27.48
|
469
|
29.49
|
+32
|
+2.01
|
Agricultural land
|
233
|
14.65
|
284
|
17.86
|
+51
|
+3.21
|
Settlement
|
7
|
0.44
|
13
|
0.81
|
+6
|
+0.37
|
Total
|
1590
|
100
|
1590
|
100
|
|
LU/LC Change Detection for 1995 to 2005
When the land uses land cover change detection for the year 1985 to 1995 compared with land use land cover change detection 1995 to 2005, there were similar trends that showed decrease or increase in particular land use land cover. The land uses land cover categories, which showed an increase are an open forest, agricultural land, and settlement for 470 Sq. Km (29.55%), 316 Sq. Km (19.87) and 14 Sq. Km (0.88%); respectively in the year 2005. On the other hand, the land use land cover categories like dense forest showed decreasing pattern amounted to 790 Sq. Km (49.68%) for the same period.
In the year between 1995 and 2005, dense forest and agricultural land show a remarkable change to other land cover classes. About 34 Sq. Km of dense forest was converted to agricultural land and open forest followed by settlement. In general, based on the matrix result, it was concluded that open forest, agricultural land, and settlement showed incremental changes with the total percentage of +0.06, +2.01, and +0.07 respectively. This improvement could be attributed to the implementation of plantation agriculture in the study area. The percentage of open forest and settlement has shown a slight increase from 469 Sq. Km (29.49) in 1995 to 29.55Sq. Km (0.88) in 2005 and 13 Sq. Km (0.81%) in 1995 to 14 Skim (0.88) respectively.
Figure 13 illustrates the matrix map result of land use/land cover change in the year between 1995 and 2005. The result depicts 34 Sq. Km (2.14%) of dense forest area were changed to other land cover type in the 10-year duration. Thus, this very large amount of land cover type was changed to agricultural land this is mainly because of population growth, declining of traditional forest-related knowledge and conservation culture and the introduction of plantation agriculture in the study area.
The change has an adverse impact on the physical environment as degradation of natural resources, deforestation, soil erosion, soil fertility reduction, biodiversity losses are the main results of the land cover change in the study area. The following map (Figure 12) showed the coverage of LU/LC in the years between 1995 and 2005.
Table 12: Land Use Land Cover Change Transition Matrix from 1995 – 2005
|
The area in 1995 (Sq. Km)
|
(%) Land Cover in 1995
|
The area in 2005 (Sq. Km)
|
(%) Land Cover in 2005
|
Change between 1995and 2005
|
|
|
|
|
|
|
The area in Sq. Km
|
%
|
Dense forest
|
824
|
51.82
|
790
|
49.68
|
-34
|
-2.14
|
Open forest
|
469
|
29.49
|
470
|
29.55
|
+1
|
+0.06
|
Agricultural land
|
284
|
17.86
|
316
|
19.87
|
+32
|
+2.01
|
Settlement
|
13
|
0.81
|
14
|
0.88
|
+1
|
0.07
|
Total
|
1590
|
100
|
1590
|
100
|
|
LU/LC Change Detection for 2005 to 2015
In the time period between 2005 and 2015, a dramatic decrease in the dense forest was observed which is about 790 Sq. Km (49.68%) of dense forest in the year 2005 to 514 Sq. Km (32.32%) in the year 2015 was noticed; the dense forest was converted into open forest, agricultural land and settlement respectively. About 276 Sq. Km (17.36 %) of dense forest was directly converted to open forest, agricultural land, and settlement in between 2005 and 2015. open forest, agricultural land, and settlement were shown to have incremental changes from 2005 to 2015.
As can be seen from Figure 13 matrix map the coverage of agricultural land shows the greatest change compared to open forest and settlement. Open forest and settlement increased by 13 Sq. Km (0.63%) and 9 Sq. Km (0.56%) respectively whereas agricultural land 276 Sq. Km (17.36%). The following matrix map (Figure 14) showed coverage of LU/LC in the years between 2005 and 2015.
Table 13: Land Use Land Cover Change Transition Matrix from 2005 – 2015
|
The area in 2005 (Sq. Km)
|
(%) Land Cover in 2005
|
The area in 2015 (Sq. Km)
|
(%) Land Cover in 2015
|
Change between 2005 and 2015
|
|
|
|
|
|
|
The area in Sq. Km
|
%
|
Dense forest
|
790
|
49.68
|
514
|
32.32
|
-276
|
-17.36
|
Open forest
|
467
|
29.55
|
480
|
30.18
|
+13
|
+0.63
|
Agricultural land
|
316
|
19.87
|
572
|
35.97
|
+256
|
+16.1
|
Settlement
|
14
|
0.88
|
23
|
1.44
|
+9
|
+0.56
|
Total
|
1590
|
100
|
1590
|
100
|
|