Linking Land Cover Change To Ecosystem Services In Nepal's Ratuwa River System

Abstract

Changes in land cover due to anthropogenic as well as natural phenomenon pose a big threat to the vulnerable Churia of Nepal and especially to the Ratuwa River System that supports essential ecosystem services (ES) that local people rely on. This paper examines how land cover change can erode and affect provisioning and regulators of the important ES in Ratuwa watershed, which is based on the previous estimation of the dynamics of land cover change between 2000 to 2023. We employed a supervised class vehicle and post processing the multi-temporal Landsat satellite data usages (2000, 2010 and 2023) to classify land cover. The ES assessment involved sediment retention, water yield and habitat quality modelled through the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) suite.

Findings show that there is a drastic change in the land cover; there was a net loss of dense forest (-12.3%) and shrubland (-5.1%) due to population growth and expansion of subsistence agriculture, as well as major improvement of infrastructure with an increase in agricultural land (+9.8%) and settlement/bare land (+7.6%). Such transfers greatly worsened the provision of ES. InVEST models forecast up to 22 percent increment of average annual sediment export in the watershed and this was strongly related to forest cover loss of steep slopes. Only a moderate improvement in water yield was observed (+8%) as a result of lowered evapotranspiration as a result of the forest loss, with an increased variability and possible negative effect on the seasonal water scarcity. Change in the scores of the habitat quality in converted areas reduced (-18%) in areas that are being converted to agriculture and settlements.

This study forms an explicit empirical association between definite conditions of land space changing with quantifiable wear and tear of important ES in the Ratuwa Churia. These measurements confirm the necessity of effective integrated methods of watershed management that would focus on preserving forests, agricultural sustainability, and soil erosion prevention to ensure the continuity of ecosystems and communal resilience. The combined approach which integrates geospatial analysis, ES modelling and local knowledge establishes a solid design that can be used in other areas with similar vulnerable mountain landscapes in Nepal.