Hydro- climatological study of Gilgit River Basin Pakistan

Study conducted to estimate the extent of glaciers in Gilgit region of Pakistan.

1. 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 1

2. HYDRO CLIMATOLOGICAL STUDIES OF GILGIT RIVER BASIN, PAKISTAN FTD Muhammad Irfan

3. CONTENTS INTRODUCTION LITERATURE REVIEW RESEARCH GAP RESEARCH CONTRIBUTION/NOVELTY METHODOLOGY RESULTS & ANALYSIS PRACTICAL & INDUSTRIAL ASPECTS CONCLUSION FUTURE DIRECTIONS REFERENCES 3 6/8/2024 Hydro Climatological Studies of Gilgit River Basin

4. INTRODUCTION Glaciers in Karakor a m provide around 80% of overall average headwater in Indus river system Hindu-Kush-Himalayas (HKH) are significant indicator of climate change and are sensitive to variations in precipitation patterns and occurrence as well as durational shifts in snow and ice melt Gilgit sub basin is an important watershed/catchment of upper Indus and it provides significant amount of runoff to downstream 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 4

5. INTRODUCTION Accurate and comprehensive knowledge of glaciers state is of utmost important for water resource management Glaciers at large exist in remote mountainous rugged terrains Difficult to monitor using field observations Hence, Glacial changes may be efficiently analysed by remote sensing tools with temporal and spatial analysis 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 5

6. BRANCHES OF HYDROLOGY ( XIAO-FANG ET.AL 2013) 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 6

7. LITERATURE REVIEW Review of literature has been made in order to find research gaps Literature review has been divided into various categories More than 160 papers , articles and seminars consulted Mostly related to Himalaya and Karakorum mountain ranges Glaciers/alps of Europe and North/South poles ice sheets were also reviewed Use of RS and Landsat imageries for their application in various fields also studied 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 7

8. OBJECTIVES The overall aim of this proposed research is to improve the knowledge of climate and hydrology of the Gilgit river basin in Pakistan and the seasonal variations of these parameters. This aim is strategically characterized through following objectives To study / perform satellite based mapping of five large glaciers in Gilgit river watershed using time series of remote sensing To investigate/study multi-sensors DEM data for extraction of Gilgit watersheds/ catchments To evaluate time series of areal extents of glaciers To identify / analyze surge / retreat or stability of selected glaciers Climatological data analysis (Temperature, Solar Radiation and Precipitation) 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 8

9. METHODOLOGY 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 9

10. Study Area Lies between longitude 72° 25' 02'' E to 74° 19' 25'' E and latitude 35° 46' 05'' N to 36° 51' 16'' N Contains six major valleys including Gupis, Puniyal, Phandar, Gilgit, Ishkoman and Yasin Phandar , Yasin and Ishkoman contain three small rivers/lakes which join major Gilgit River Basin ( Ali, et al., 2019) Large glaciers in Gilgit river basin are Phakor, Karamber, East Gammu, Bhort and Bad-e-Swat 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 10

11. Study Area 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 11

12. Study Area 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 12

13. Elevation Distribution in Study Area 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 13

14. SATELLITE DATASETS Landsat TM, ETM + and OLI satellite Imageries ο f Gilgit Basin f ο r a period of 30 years (1988, 1994, 1999, 2014 and 2018) used Glacier changes had been extracted from the Landsat imageries Processes were applied on imageries of satellite in order to remove atmosphere induced errors 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 14

15. IMAGERIES UTILIZED IN STUDY Satellite / Sensor Year Scene ID Path Row Cloud Cover Acquisition Date Landsat 5 TM 1988 LT05_L1TP_150035_19881027_20170205_01 150 35 3% 27-10-1988 Landsat 5 TM 1994 LT05_L1TP_150035_19940708_20170113_01 150 35 4% 08-07-1994 Landsat 7 ETM + 1999 LE07_L1TP_150035_19990916_20170217_01 150 35 1% 16-09-199 Landsat 8 OLI 2014 LC08_L1TP_150035_20140917_20170419_01 150 35 1.25% 17-09-2014 Landsat 8 OLI 2018 LC08_L1TP_150035_20180912_20180927_01 150 35 1.41% 12-09-2018 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 15

16. DEM Data Used in Study Involving Delineation of Watershed No. Imagery ID Sensor Date of Acquisition/Publication of reference Coordinate row , path Resolution 1 SRTMIN35E074V3 SRTM- SIR/C – X/SAR 23 SEP 14 JPL-NASA (2014) Farr et al. (2007) 35, 74 1 arc second-30m 2 ASTGTMV003-N35E074 ASTER GDEM 01-03-2000 to 30-11-2013 Tachikawa et al. (2011) 35, 74 1 arc second-30m 3 GT30E060N40 GTOPO30 1-12-1996 Denker (2005) USGS-EROS (1996) 15, 80 30 arc second– 1000 m 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 16

17. Data Processing 6/8/2024 17 Hydro Climatological Studies of Gilgit River Basin

18. LANDSAT DATA PROCESSING METHODOLOGY 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 18

19. RESULTS AND ANALYSIS EXTRACTION OF WATERSHED 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 19

20. EXTRACTION OF WATERSHED THROUGH ASTER GDEM Total area of watershed 12757.44 km 2 Elevation range 1388 m to 7104 m Average peak at an elevation of 4051.9m Five glaciers are delineated shown in red polygons Black dot in each glacier watershed represent pour point 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 20

21. WATERSHED EXTRACTION Delineated watersheds based on ASTER GDEM 30 m 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 21 Phakor Bad-e- Swat Bhort Karamber East Gammu Bad-e-Swat Bhort

22. Watershed Extraction from ASTER GDEM shown with Landsat 8 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 22 Bhort

23. EXTRACTION OF WATERSHED THROUGH SRTM 30 Total area of watershed 12760.996 km 2 Elevation range 1405 m to 7114 m Average peak at an elevation of 4046.6m Five glaciers are delineated shown in red polygons Black dot in each glacier watershed represent pour point 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 23

24. Delineated Watersheds Extracted from SRTM 30 m Gilgit Basin 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 24 E.Gammu Karamber Bhor t Bad-e- Swat t Phokar

25. Delineated Watersheds Extracted from SRTM 30 m shown with Landsat-8 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 25

26. Comparison Analysis of DEMs ( Sq.Km ) DEM dataset Gilgit basin Bad-e-Swat Bhort East Gammu Karamber Phakor SRTM 12760.99 45.914 53.857 57.781 223.807 24.077 ASTER GDEM 12757.44 49.410 54.698 42.730 223.916 20.356 GTOPO30 12711.14 - - - - - 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 26

27. Difference of watershed- Bhort Glacier 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 27 Red polygon represent watershed delineated through SRTM Black polygon represents watershed delineated through ASTER GDEM Mismatches highlighted in circle Both watersheds visually studied through Landsat 8 OLI ridge matching SRTM 30 m radar based imagery showed additional correctness and accurate delineation

28. Bhort – Polygons are combined to highlight mismatches for the comparison of watersheds derived from SRTM (Red) and ASTER-GDEM (Black) 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 28

29. Conclusion on Extraction of Watershed 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 29 Based on results data showed SRTM 30 m radar based DEM is more accurate Due combination with optical remote sensing imagery Attributes and features of both DEMs however show close agreement to each other Watershed extraction characteristics important for water resource management and hydrological analysis GTOPO30 DEM being of low resolution(1km) used only for Gilgit basin extraction

30. RESULTS AND DISCUSSION GLACIER CHANGE ANALYSIS 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 30

31. GLACIER CHANGE Object based classification quicker in computation and efficient due spectral pattern consideration It gives better and accurate results compare to pixel based classification Temporal satellite images of Landsat for the year from 1988 to 2018 acquired and analyzed 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 31

32. Bade e Swat 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 32 One of main glacier in Gilgit region Terminus starts at 2802 m above sea level Located at 36 o 32’ 20” N and 74 o 02’ 15” E Results revealed overall ice-covered area for 30 years has been reduced in all years except 1988 Debris covered area from 1988 to 2018 has increased to 0.52 sq km

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34. Phokar Glacier 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 34 Phokar glacier is one of major glacier in Gilgit region Terminus starts at 4010 masl Located at 36 o 20‘55‘‘N and 74 o 00‘05‘‘ E Results revealed overall ice-covered area from 1988 to 2018 has reduced to 1.17 sq km Interestingly , debris covered area also reduced to 0.15 sq. km

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36. East Gammu Glacier 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 36 East Gammu glacier is one of major glacier in Gilgit region Terminus starts at 2800 masl Located at 36 o 38‘30‘‘N and 73 o 24‘10‘‘ E Results revealed overall ice-covered area for 30 years has been reduced in all years except 1988 Debris-covered area from 1988 to 2018 has decreased to 0.37 sq km

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38. Karamber Glacier 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 38 Karamber glacier is one of biggest glaciers in Gilgit region Terminus starts at 2850 masl Located at 36 o 36‘55‘‘N and 74 o 04‘10‘‘ E Results revealed overall ice-covered area from 1988 to 2018 has reduced to 4.74 sq km Overall debris-covered area from 1988 to 2018 has increased to 2.7 sq km

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40. Bhort Glacier Bhοrt is among one of largest glacier in region of Gilgit with a significant part under debris cover Terminus starts at 3000 m asl Located at 36 ο 33‘ 52‘‘ N and 74 ο 04‘ 28‘‘ E Results revealed overall ice-covered area from 1988 to 2018 has reduced to 4.11 sq. km Overall debris-covered area from 1988 to 2018 has increased to1.47 sq km 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 40

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42. Computed Temporal Glacier Cover Area (Clean Ice) in Km 2 Glacier Name /Year 1988 1994 1999 2014 2018 Bad-e-Swat 11.7668 14.1341 11.5204 12.7214 11.6703 Phakor 7.2744 7.0202 6.8960 6.3270 6.1407 East- Gammut 9.0290 12.3895 11.4754 9.9720 9.7758 Karamber 57.9256 58.0387 51.3600 51.2669 53.1855 Bhort 14.0261 10.8782 10.2054 9.6538 9.1962 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 42

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44. Computed Temporal Glacier Cover Area (Debris Cover) in Km 2 Glacier Name /Year 2018 2014 1999 1994 1988 Bad-e- Sawat 1.0015 1.0610 1.0071 0.5721 0.4804 Phakor 0.3321 0.3735 0.1656 0.4845 - East- Gammu 0.3195 0.4743 0.3695 0.6309 0.6811 Karamber 8.0307 7.3377 8.0000 5.0016 5.3305 Bhort 2.4597 2.8685 2.7959 2.2377 0.9815 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 44

45. Glacier-wise Change Trends for Debris Covered Ice 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 45

46. Computed Temporal Glacier Cover Area (Combined) in Sq.Km 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 46 Glacier Name /Year 2018 2014 1999 1994 1988 Bad-e- Sawat 12.6718 13.7824 12.5275 14.7062 12.247 Phakor 6.4728 6.7005 7.061615 7.50469 7.2743 East- Gammut 10.0953 10.4463 11.8449 13.0204 9.7101 Karamber 61.2162 58.6046 59.3600 63.0403 63.256 Bhort 11.6559 12.5223 13.0013 13.1159 15.0076

47. Computed Temporal Glacier Cover Area (Combined) in sq. Km 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 47

48. RESULTS AND DISCUSSION CLIMATOLOGICAL DATA ANALYSIS 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 48

49. CLIMATOLOGICAL DATA ANALYSIS For numerous uses, records with a high ( 1km) spatial resolution are preferred because they detect ecological deviations that are misplaced at lesser spatial resolutions, especially in hilly and rugged regions with strong climate inclines Hijmans et al. (2005) delivered WοrldClim version 1 climate database for 1970-2000, for global land areas, comprising of continuing normal monthly temperature and rainfall (Fick and Hijmans 2017 ) Used here to study variations of lowest and extreme temperature, solar energy and precipitation by means of sub-set from original global grids 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 49

50. MINIMUM TEMPERATURE PROFILE OF GILGIT WATERSHED 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 50

51. MINIMUM TEMPERATURE PROFILE OF GILGIT WATERSHED Global grids of monthly averaged 30 years data was obtained Subset of study area was extracted to obtain regional temperature values Interpolated minimum surface temperature portrays a high value of -0.2 o C and low value of -35.1 o C for month of January Low values of temperature are mainly observed at high altitudes on northern side and high values of temperature on lower altitudes on southeast of Gilgit watershed January is the frosty winter coldest month in Gilgit 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 51

52. Spatial Distribution of Monthly Averaged Minimum Temperature – January 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 52

53. Yearly Low and High Values for Minimum Temperature in o C of Gilgit Watershed 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 53 Month T min(low) T min(high) T min( avg ) January - 35.1 -0.2 -17.65 February -36.4 2.8 -16.8 March -33.4 6.8 -13.3 April -25.7 11.4 -7.15 May -20 15.1 -2.45 June -16.3 19.2 1.45 July -13.1 22.5 4.7 August -12.7 22.3 4.8 September -16.6 17.4 0.4 October -21.3 11 -5.15 November -27.9 4.7 -11.6 December -33.2 1.2 -16

54. Spatial Distribution of Monthly Average Minimum Temperature - Normalized Matrix of Yearly Profile 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 54

55. Maximum Temperature Profile of Gilgit Watershed 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 55

56. Maximum Temperature Profile of Gilgit Watershed Highest temp of day is max temp Interpolated max surface temperature processed from point data of local stations portrays a high value of 10.7 o C and a low value of -24.7 o C for month of January Low value mainly observed at higher altitudes on northern side High value of temperature observed on lower altitudes southeast of Gilgit watershed 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 56

57. Spatial Distribution of Monthly Averaged Maximum Temperature for January 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 57

58. Monthly Low and High Values for Maximum Temperature in Gilgit Watershed Month T Max (Low) T Max (High) T Max (Ave) January -24.7 10.7 -7 February -24.6 13.4 -5.6 March -21.8 19 -1.4 April -18.2 25 3.4 May -13.4 30.2 8.4 June -8.8 35.3 13.25 July -3.9 37.2 16.65 August -4.1 36.3 16.1 September -8 32.5 12.25 October -14.4 26.5 6.05 November -19.3 19.7 0.2 December -21.8 13 -4.4 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 58

59. Spatial Distribution of Monthly Averaged Maximum Temperature - Normalized Matrix for Yearly Profile 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 59

60. Solar Radiation Intensity in Gilgit Watershed(kJ m -2 day -1 ) 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 60

61. Solar Radiation Intensity in Gilgit Watershed(kJ m -2 day -1 ) Sun based radiation (daylight) conveys energy to glacial mass surface Sun's radiation is consumed in part, and rest is reflected Energy from sun is principle well spring of energy for Earth's temperature framework In Gilgit watershed month with lengthiest days is June (Normal sunlight: 14.6h ) Month with briefest days is December (Average light: 9.8h ) Normal daylight in March is 6h while month with most daylight is June (Average daylight: 10h ) Months with the least daylight are January, February and December when the typical daylight is 5 hours. 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 61

62. Spatial Distribution of Monthly Averaged Solar Radiation - January Introduced sun powered radiation information handled from point information from neighborhood stations, month to month arrived at midpoint of 30 years, depicts a high worth of 7545 kJ m -2 day -1 and a low worth of 5641 kJ m -2 day -1 across watershed for long stretch of January Normally higher latitudes receive less solar radiation Values at 36 o N are higher than those at 37 o N Low values of solar radiation at the higher altitudes on Northern side may also be associated with the significant amount of cloud cover often present at high mountains Normally , under clear sky conditions the solar radiation increases with altitude 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 62

63. Spatial Distribution of Monthly Averaged Solar Radiation - January 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 63

64. Yearly Low and High values for Sοlar Radiation in Gilgit Watershed in kJ m -2 day -1 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 64 Month Srad (Low) srad (High) srad (Ave) January 5641 7545 6593 February 8176 10093 9135 March 11721 14075 12898 April 16793 18065 17429 May 20422 21560 20991 June 21927 24790 23359 July 18612 22605 20609 August 17000 21226 19113 September 15446 18315 16881 October 12108 14666 13387 November 7994 10765 9380 December 5436 7602 6519

65. Spatial Distribution of Monthly Averaged Solar Radiation Normalized Matrix for Yearly Profile 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 65

66. RESULTS DRAWN 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 66 The solar radiation carries energy to surface of glacier A part of the solar radiation is absorbed into glacier ice and increases temperature of the ice pack and hence becomes responsible for glacier shrinkage Other part of solar radiation is reflected back in atmosphere in form of solar albedo which is higher for fresh snow Solar radiation values provide better estimate of energy budget of glaciers

67. RESULTS DRAWN 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 67 In months of May, June and July, glaciers receive max energy in form of solar radiation and hence accelerate melting / glacier retreat Whereas solar radiation is at min in winter months During winter months the glacier melting is further reduced by the presence of cloud cover and presence of fresh snow which is responsible for more reflectance on high-altitude region in upper parts of glaciers in particular and on overall extent of the glacier in general

68. Precipitation(mm) in the Gilgit Watershed 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 68

69. Precipitation(mm) in the Gilgit Watershed Four rainy seasons in study area viz., wintertime, pre monsoon, monsoon and post monsoon precipitation ( Javed et.al. 2020) Interpolated precipitation data processed from point data from local stations monthly averaged of 30 years portrays a high value of 57 mm and a low value of 4 mm across watershed for month of January 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 69

70. Spatial Distribution of Monthly Precipitation January 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 70

71. Yearly precipitation profile(in mm) of Gilgit Watershed   Month Precip (Low) Precip (High) Precip (Ave) January 4 57 31 February 5 72 39 March 8 89 49 April 16 95 56 May 24 70 47 June 9 28 19 July 9 111 60 August 11 91 51 September 8 52 30 Οctοber 5 43 24 November 1 29 15 December 2 58 30 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 71

72. Spatial Distribution of Monthly Precipitation Normalized Matrix of Yearly Profile   6/8/2024 Hydro Climatological Studies of Gilgit River Basin 72

73. Accuracy Assessment on Mapping of Glaciers An error matrix is a common quantitative tool for determining picture categorization accuracy It's a table that shows how categorization result and a reference image correspond Ground veracity data gathered during the field survey was used to build the error matrix Ground truth classes are in table's columns, and classes of categorised image to be assessed are in table's rows Number of pixels for all conceivable correlations between ground truth and categorised image are shown in table's cells The matrix's diagonal essentials have been shaded and highlighted Number of accurately detected pixels is contained in diagonal cells The entire number of pixels has been divided by the sum of these pixels to get the overall classification accuracy 'p a ', which is 87.50 percent 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 73

74. Accuracy Assessment on Mapping of Glaciers Error Matrix 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 74   Class   Glc   Debris Water bodies Other (rocks etc ) Row Total User Accuracy (UsAc) [on a scale of – 1] Glacier Cover 133 6 3 142 0.937 Debris Cover 8 35 43 0.814 Water Bodies 20 1 21 0.952 Other (rocks etc ) 4 2 38 44 0.864 Col Total 145 41 22 42 250   Producer Accuracy (PrAc) [on a scale of – 1] 0.917 0.854 0.909 0.905  

75. Kappa Coefficient 250 ground truth reference data points were obtained utilizing error matrix approach and stratified random sampling For category matching, these ground truth locations were superimposed on the land use land cover map Correct values fall along matrix's primary diagonal ( Morgado et al., 2012). Classified values are incorrectly placed in off diagonal sections of matrix, making it obvious which class they belong to ( Mundia and Murayama 2009 ). 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 75

76. Overall Accuracy Overall accuracy is calculated by dividing the diagonal sum with the total number of data points 𝑂𝑣𝑒𝑟𝑎𝑙𝑙 𝐴𝑐𝑐𝑢𝑟𝑎𝑐𝑦 = 90.4%   6/8/2024 Hydro Climatological Studies of Gilgit River Basin 76

77. Kappa Coefficient Kappa coefficient is calculated from the following relationship Kappa Coefficient = 0.8414 Kappa Coefficient = 84.14%   6/8/2024 Hydro Climatological Studies of Gilgit River Basin 77

78. Result drawn Classification findings similarity to random values gauged by KAPPA 84% is a good agreement as it is more close to 100 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 78

79. CONCLUSION 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 79 This study provides a better insight into glacier status in study area, as health of glacier over 30 years has been monitored and result suggest an inverse pattern as to the concepts of rapid glacier melting which does not exist in study area Different remote sensing products / datasets have been compared include SRTM, ASTER and GTOPO for watershed delineation These multi-sensor DEM data have been used for extraction of watersheds/catchments and accuracy of results has been analyzed in this region. This provides the confidence level about the addressing most important question that which satellite product is most suitable in this study area.

80. CONCLUSION 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 80 Areal extents of five large glaciers have been analyzed. It appears that at large, summer depletion balances winter accumulation. This indicates the absence of strong depletion of glaciers over three decades time and suggests / confirms that winter accumulation on glaciers in the Gilgit river basin has strong influence, which is of same order of ablation in summer season Investigation into the variations of glaciers make strong believe to conclude the absence of any major surge or retreat in studied period and hence stability of the selected glaciers has been agreed

81. CONCLUSION 6/8/2024 Hydro Climatological Studies of Gilgit River Basin 81 Long-term climate data of 30 years monthly averages have been analyzed Temperature remains positive in most of months in summer which together with solar radiation is responsible for glacier melt Negative temperatures especially in winter months accounts for freezing and re-freezing of snowfall/ rainfall/ precipitation