Effects on ecosystem services value due to land use and land cover change (1990–2020) in the transboundary Karnali River Basin, Central Himalayas

Valuation of ecosystem services based on land use and land cover changes (LUCC) offers an incentive to people for sustainable use of the natural resources and can encourage people to adjust the land use sustainably. In this study, we used “Object-based Image Analysis (OBIA),” a remote sensing technique to extract the land use and land cover (LULC) of the transboundary Karnali River Basin (KRB, China and Nepal) from 1990 to 2020, and ecosystem services value (ESV) coefficients derived for the Tibetan Plateau has been used to assess the ESV. The basin has highest percentage of forest (33.44%), followed by bare area (30.29%), shrub/grassland (18.5%), agriculture (13.12%), snow/ice (4.36%), waterbody (0.3%), and built-up (0.03%) as of 2020. Over 30 years, 4.07 km2 of the forest has been converted to agricultural land, 3.31 km2 of agricultural land has been encroached by built-up area, whereas 2.82 km2 of snow/ice area has melted into the waterbody. Furthermore, 80.85 km2 of bare area has been converted to snow/ice, and 2138.83 km2 of snow/ice has been changed to bare area. The ESV of KRB has increased by nearly 2.7 million USD from 1990 to 2020, primarily due to the increase in ESV from the conversion of 133.09 km2 of snow/ice to shrub/grassland. The ESV of forest, waterbody, and snow/ice has decreased, whereas it has increased for other LULC classes in the basin. Spatial distribution of LUCC and assessment of ESV can be a tool to facilitate for better provisioning and regulating the resources for the future.

Land Use and Land Cover Dynamics and Assessing the Ecosystem Service Values in the Trans-Boundary Gandaki River Basin, Central Himalayas

Land use and land cover is a fundamental variable that affects many parts of social and physical environmental aspects. Land use and land cover changes (LUCC) has been known as one of the key drivers of affecting in ecosystem services. The trans-boundary Gandaki River Basin (GRB) is the part of Central Himalayas, a tributary of Ganges mega-river basin plays a crucial role on LUCC and ecosystem services. Due to the large topographic variances, the basin has existed various land cover types including cropland, forest cover, built-up area, river/lake, wetland, snow/glacier, grassland, barren land and bush/shrub. This study used Landsat 5-TM (1990), Landsat 8-OLI (2015) satellite image and existing national land cover database of Nepal of the year 1990 to analyze LUCC and impact on ecosystem service values between 1990 and 2015. Supervised classification with maximum likelihood algorithm was applied to obtain the various land cover types. To estimate the ecosystem services values, this study used coefficients values of ecosystem services delivered by each land cover class. The combined use of GIS and remote sensing analysis has revealed that grassland and snow cover decreased from 10.62% to 7.62% and 9.55% to 7.27%, respectively compared to other land cover types during the 25 years study period. Conversely, cropland, forest and built-up area have increased from 31.78% to 32.67%, 32.47–33.22% and 0.19–0.59%, respectively in the same period. The total ecosystem service values (ESV) was increased from 50.16 × 108 USD y−1 to 51.84 × 108 USD y−1 during the 25 years in the GRB. In terms of ESV of each of land cover types, the ESV of cropland, forest, water bodies, barren land were increased, whereas, the ESV of snow/glacier and grassland were decreased. The total ESV of grassland and snow/glacier cover were decreased from 3.12 × 108 USD y−1 to 1.93 × 108 USD y−1 and 0.26 × 108 USD y−1 to 0.19 × 108 USD y−1, respectively between 1990 and 2015. The findings of the study could be a scientific reference for the watershed management and policy formulation to the trans-boundary watershed.