The study area taken for this study is the Lahul – Spiti District located in the north-western Indian Himalayan state of Himachal Pradesh (Figure 1). The District occupies location from 31°44´57´´N to 32°59´57´´N latitude and 76°46´29´´ E to 78°41´34´´E longitude with a geographical area of 13,835 km2. Area wise, it is the largest district of Himachal Pradesh state compare to another district. Lahul – Spiti separated in the east from the Tibet region of china that forms an international border. Jammu and Kashmir district mountain Ladakh lies in the north and Chamba district to its southwest and west. Towards, southeast and south it makes boundary with Kullu and Kinnaur districts of the state. The mountains adorn it is surrounding with various ice-capped glaciers and therefore the entire region includes a rugged parcel of land. The great Himalayan vary keeps it for the most part isolated from the remainder of the country the neighbouring territories for almost half a year.

Table 1

Sl. No	Data	Sensor	Swath (km)	Spectral Resolution (µm)	Spatial Resolution (m)	Temporal Resolution (days)	Radiometric Resolution
1	Landsat 7	EMT+	185	Blue:0.450 – 0.515 Green:0.525 – 0.605 Red:0.630 – 0.690 NIR:0.750 – 0.900 NIR:1.55 – 1.75 Thermal:10.40 – 12.50 MIR:2.08 – 2.35 PAN:0.52 – 0.90	30 × 30 30 × 30 30 × 30 30 × 30 30 × 30 60 × 60 30 × 30 15 × 15	16	8 bit
2	Landsat 8	OLI TIRS	185	Visible:0.433 – 0.453 Blue:0.450 – 0.515 Green:0.525 – 0.600 Red:0.630 – 0.680 NIR:0.845 – 0.885 SWIR 1: 1.56 – 1.66 SWIR 2: 2.1 – 2.3 PAN:0.52 – 0.90 Cirrus1.36 - 1.39 TIRS 1: 0.3 – 11.3 TIRS 2: 11.5 – 12.5	30 × 30 30 × 30 30 × 30 30 × 30 30 × 30 30 × 30 30 × 30 15 × 15 30 × 30 100 × 100 100 × 100	16	12 bit



Table 2

Data	Path	Row	Date of acquisition
Landsat 7		37	2005-10-29
Landsat 7	147	38	2005-10-29
Landsat 7	146	38	2005-10-22

Table 3

Data	Path	Row	Date of acquisition
Landsat 7	147	38	2010-10-11
Landsat 7	147	37	2010-10-11
Landsat 7	146	38	2010-11-05

Table 4

Data	Path	Row	Date of acquisition
Landsat 8	147	38	2015-10-17
Landsat 8	147	37	2015-10-17
Landsat 8	146	38	2015-10-10

Table 5

Data	Path	Row	Date of acquisition
Landsat 8	147	38	2019-10-28
Landsat 8	147	37	2019-10-12
Landsat 8	146	38	2019-10-21

Figure 2

Land use change detection in the study area.

The maps for LULC of Lahul – Spiti District were produced using supervised classification techniques on Landsat satellite imagery for 2005, 2010, 2015 and 2019(Figure 3&4). The classification process started with the identification of training sets representing different land-use classes. These training sets were used for supervised classification using a maximum likelihood classification (MLC) algorithm. The maximum likelihood classification is the most accurate and reliable classifier (Richards and Jia, 1999; Foody et al., 1992; Saha et al. 2005) the pixels in the unknown class are assigned to a specific land-use class of which it has the greatest likelihood of membership. In this analysis, five major classes of land use/land cover are identified: snow/glacier, barren/rocky surface, forest, agriculture/grass, and water. The area of each class can be estimated using the Field Calculator tool in ArcGIS. Graphs for various land use classes in the area were produced in MS Excel. (Figure 5)

Table 6

Land use/Land cover Class		Area (Percent)				Percent Change (05 - 19)
		2005	2010	2015	2019
1.	Snow/Glacier	27.313	45.491	37.145	39.155	43.357
2.	Barren/Rocky Surface	55.219	47.188	53.762	52.286	-5.312
3.	Forest	4.343	2.528	1.137	1.587	-63.458
4.	Water	0.061	0.062	0.057	0.047	-22.951
5.	Agriculture/ Grass	13.064	4.731	7.899	6.925	-46.992
		100.00	100.00	100.00	100.00

Figure 4

The Landsat satellite imagery for the 20-year duration (2005, 2010, 2015, and 2019) was categorized and contrasted for land use and land cover analysis in the following study. The results obtained were illustrated in the study of satellite imagery (Figs. 3, 4). In Table 6, total area coverage of different classes of land use was given. A short description of the outcomes was discussed in the corresponding paragraph.

The Lahul- Spiti district is mainly covered by Barren/Rocky Surface (more than 50%). In the last 20 years, snow cover is constantly increasing resulting in a decrease in Barren/Rocky Surface. The snow cover increased by 44 percent while barren surfaces reduced by about 6 percent during 2005-2019 (table 7). The forest cover in the area shows a large change and has reduced by about 64 percent. The area under Agriculture/Grass shows a considerable reduction (47%) during 2005-2019. The area under water also reduced by 23 percent. The distribution of land use/land cover is shown in table 6. The whole area sloppy mountains and agriculture is practiced on sloppy lands. The total area coverage for the different years is given in Table 6 and Fig. 5 shows the graph of the temporal differences between the year of each LULC characteristic (2005 to 2019).