River ecosystems worldwide support a wide variety of biodiversity (Elosegi et al., 2010) and are crucial for sustaining human livelihoods and traditions by offering various benefits such as food, water, and recreational spaces (Gowda et al., 2015; Hanna et al., 2018). These benefits derived from ecosystems are termed ecosystem services, which can be categorized into cultural, providing, regulating, and supporting services (Assessment, 2005). As the demand for riverine ecosystem services rises, there is a risk to their sustainable provision (Durance et al., 2016; Small et al., 2017). Research indicates that riverine ecosystems are crucial for livelihoods but are also facing significant threats (Beck et al., 2012; Dudgeon et al., 2006; A. J. Reid et al., 2019). The concept of ecosystem services offers a comprehensive approach to assessing how ecosystems contribute to human well-being, presenting a promising strategy for effective riverine management (Brauman et al., 2014; Bunch et al., 2011).
The Danro River, a tributary of the Ganges River basin serves as one instance where unlawful sand extraction occurs frequently, resulting in environmental deterioration throughout several sections of the river. Illegal sand mining exacerbates the adverse effects on riverine ecosystems compared to legal operations, primarily because it often occurs without regard for environmental safeguards and regulatory oversight (Ghosh & Jana, 2021). Some specific impacts include the disruption of carbon storage mechanisms in riparian zones, contributing to greenhouse gas emissions and climate change (Qin et al., 2020). Channel incision, bank collapse, and loss of vegetation resulting from illegal sand mining reduce habitat quality for aquatic organisms and contribute to declines in biodiversity (Ghosh & Jana, 2021; Koehnken & Rintoul, 2018). Altered hydrology and sediment distribution following illegal sand mining can disrupt nutrient cycles, leading to shifts in community composition and productivity (Koehnken et al., 2020). Unregulated sand mining causes excessive sediment loading, leading to increased turbidity and smothering of aquatic life (Ghosh & Jana, 2021; Koehnken & Rintoul, 2018). Other consequences of sand mining include land degradation, loss of agricultural lands, biodiversity decline, and increased poverty among affected communities. Additionally, sand mining contributes to increased shoreline erosion, reduced protection from storms, and economic losses through tourism abandonment and aesthetic damage. Regulating and controlling illegal sand mining is crucial to preserving the integrity of riverine ecosystems and ensuring sustainable development (Ghosh & Jana, 2021).
Few studies have systematically quantified the ecosystem service potential of whole river ecosystems. A number have targeted only single services, such as nitrogen retention (Basak et al., 2021; Burgin et al., 2013; Vermaat et al., 2016); water quality (Gilvear et al., 2019; Keele et al., 2019; Stammel et al., 2021); water provision (Notter et al., 2012) and flood regulation (Asbjornsen et al., 2022; Hill et al., 2023; Liu et al., 2021). There remains a paucity of tools to assess and quantify the ecosystem services generated by often complex river reaches and stream networks (Palmer & Ruhi, 2019).
The majority of studies on the assessment of ecosystem services (Colson & Cooke, 2018; Daniel et al., 2012; Johnston & Bauer, 2020; Martínez-Harms & Balvanera, 2012) combine mathematical techniques with measured data, however, some studies struggle to finish the task due to a dearth of measured data (Koschke et al., 2012). Through the advancement of Geographic Information Systems (GIS) and Remote Sensing (RS), models such as the Soil and Water Assessment Tool (SWAT) (Douglas-Mankin et al., 2010), Hydrological Simulation Programme Fortran (HSPF) (Donigian Jr et al., 1995), and Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) (Cong et al., 2020) have been built and utilised to evaluate ecosystem services in recent years. This research uses the InVEST model, created by the Natural Capital Project, a collaborative effort between the University of Minnesota, The Nature Conservancy, Stanford University, and the World Wildlife Fund. The InVEST model is notably preferred due to its straightforward, swift, and robust spatial portrayal, particularly in situations with limited data when evaluating ecosystem services. InVEST uses a gridded map and an average annual time step, in contrast to other hydrological models. It is suitable for assessing the consequences of alterations in land use on an array of ecosystem services because it only requires a small amount of data and knowledge. These services include water yield, carbon retention, and habitat quality (Lüke & Hack, 2018; Vigerstol & Aukema, 2011). Furthermore, it has mapping and spatial analysis features under ArcGIS, and the outputs can be presented as shapefiles, tables, or gridded maps (Ashkezari et al., 2018; Moreira et al., 2018; Yang et al., 2019).
The review of the literature revealed that no studies have been done in the region under consideration or in most parts of the Indian subcontinent regarding the impact of LULC on ESs. To address these concerns, we applied the InVEST model with localized tailored settings to simulate and estimate changes in ecosystem services of the Danro River Basin in the Garhwa-Palamu districts of Jharkhand from 2000 to 2022. Danro River Basin lies in the semi-arid region and is vulnerable to significant soil loss risk due to several variables such as changing land use and rainfall. Additionally, fertilizer inputs have caused the trophic state of the Danro River Basin in Jharkhand to continuously shift from mesotrophic to eutrophic and thus the river is at risk of sedimentation. According to (Cai et al., 2023; Goshu et al., 2017), toxic cyanobacteria and faeces are present in rivers' mouths and shorelines. Sediment, fertilizers, animal manure, and manufacturing waste are the primary sources of nitrogen and phosphorus (J. Zhang et al., 2022). Consequently, the key objectives of this study were to: (i) estimate the LULC change in the Danro River Basin between the years 2000 and 2022; (ii) to analyse ES changes in response to LULC; and (iii) to investigate the complex relationships between ecosystem services and land use changes, emphasizing tradeoffs and synergies.