1. Introduction
Human production and survival rely heavily on the structures, functions, and processes of ecosystems [
1]. These ecosystems provide vital ecological processes that ensure people can live well and produce ecological products essential for human survival [
2,
3]. Consequently, ecosystems are critical for promoting healthy growth and ensuring human well-being [
4,
5]. Land use plays a crucial role in shaping how environmental benefits are produced, distributed, and utilized, and changes in land use can have significant impacts on ecosystem products, services, and their availability. Thus, land use changes can directly affect ecosystems’ capacity to provide essential services to support human life [
6,
7,
8].
To evaluate the functions of ecosystems in a systematic way, Costanza proposed an approach based on the relationship between ecosystem services and functions, which was further developed with Kellert’s loss–benefit method for a standardized quantitative evaluation of biosphere materials in 1984. Building upon this foundation, Costanza and others developed a transfer-of-interests approach and evaluated 17 ecosystem services in the global biosphere, which identified the world’s first ESV coefficient [
9,
10]. Currency units were used to calculate the changes in ESV caused by changes in land use [
11]. These studies have been conducted on regional and global scales and have used various accounting methods, such as the unit value approach summarized by Xie et al. [
12,
13,
14,
15]. Scholars have used different approaches to estimate ESV, including the ESV proposed by Biratu et al. and land use/cover change (LUCC)-based ES assessments recommended by Fontaine et al. [
16,
17]. It is essential to recognize that different land use and management patterns can change the original structure and layout and recharge patterns of ecosystems, which can affect their service function [
18]. Bojie et al. have analyzed the limitations of previous ES valuation studies and broadened research ideas for future generations to carry out related studies [
19,
20]. As human production and life continue to promote land use change, analyzing and evaluating the value of ES based on this foundation can help optimize land planning [
21]. This is crucial for socially, economically, and ecologically coordinated sustainable development.
Basin ecosystems play a crucial role in providing a wide range of products and services to the public, such as water resources, sand and windbreak preservation, wildlife protection, and recreation opportunities [
22,
23]. However, human activities have significantly impacted most of the river basins in the world, particularly in China’s arid and semi-arid areas, which face a double dilemma of climate change and the lagging economic development of a fragile ecological environment. To address this, EWC has been implemented since 2000 in several inland river basins in northwest China, such as the Tarim River Basin, the Heihe River Basin, and the Shiyang River Basin, as an effective tool to redistribute water resources and achieve sustainable development [
24]. However, EWC projects have a significant impact on hydrological regimes, local ecosystems, and socioeconomic structures, particularly in water-scarce areas [
25]. As a result, there has been a significant focus on assessing the value of ES in basin ecosystems of northwest China [
26,
27,
28,
29,
30,
31].
The Konqi River is a crucial tributary of the Tarim River, forming an integral part of the four rivers and playing a strategic role in maintaining the ecological security of the Silk Road Economic Belt. Riparian forests in the middle and lower reaches of the river are particularly important in ensuring the river’s stability [
32]. The Konqi River also serves as a critical water source for the Korla-Lopnur Oasis, providing water for agricultural irrigation, industrial use, ecological maintenance, and transfer to the Tarim River, which has important strategic value [
33]. However, with the rapid increase in population and economic activities in the Konqi River Basin, the demand for water has surged, leading to a sharp decline in ecological water and resulting in the drying up of the river and severe degradation of the desert riverbank forests [
34]. To address this issue, the state launched the Tarim River Basin Comprehensive Management Project in 2000. As part of the project, 21 EWC projects were initiated to release a total of 84.45 × 10
8 m
3 of ecological water from the Daxihaizi Reservoir to the lower reaches of the Tarim River. However, to restore the ecological environment on both sides of the Konqi River, the Xinjiang Tarim River Basin Administration launched the Konqi River Ecological Emergency Water Replenishment Project on 26 August 2016. This project involved the transfer of water from Bosten Lake to the Konqi River due to its high water level [
33]. The continuous water transfer has effectively mitigated the severe ecological degradation downstream, raised the groundwater level in the receiving area, improved groundwater quality, and increased the number of plant and animal species, leading to an overall improvement in the environment.
To achieve sustainable socioeconomic development and maintain a healthy ecosystem in the typical Konqi River Basin, it is necessary to conduct a comprehensive study on the value of ES from both a theoretical and practical standpoint. This undertaking requires a clear understanding of the spatial and temporal changes in LULC within the region. To obtain a representative sample, we have carefully selected three distinct locations, including the direct-flow formation zone, the last person’s water hub site, and the dispersal zone, to establish typical river reaches within the basin. The main objective of this study is to perform a quantitative analysis of the typical river reaches within the basin and evaluate how LULC and ESV have changed over time and space, specifically after the implementation of the EWC project. Through this analysis, we aim to establish a scientific foundation for the sustainable use of water and soil resources in the research area, which is situated within an arid and fragile ecological zone. This will contribute to ensuring national agricultural ecological security and promoting sustainable land use and ecological environment construction.
5. Conclusions
The typical Konqi River Basin provides vital ecosystem services to its administrative region. EWC, as an essential measure to mitigate ecosystem degradation in China’s northwest arid inland river basins, has a significant impact on changes in ESV in the study area. This paper aimed to analyze the land use change characteristics under EWC conditions from 2013 to 2020 and investigate the impact of EWC on ESV in the Konqi River Basin. Based on the analysis, the typical river reaches of the Konqi River were divided into the upper reaches, strongly influenced by human activities, and the lower reaches, with almost zero human activities. The value of local ES was affected by EWC under different conditions of human activity intensity after land use change. The following conclusions were drawn: (1) The dominant land use type in the upper reaches, cropland, showed a decreasing trend in area share by 2020, mainly converting to unused land (2572.03 hm2) and roads (1935.40 hm2). There was a decrease in the share of unused land area in the lower reaches, mainly converting to shrubland (4976.13 hm2) and grassland (2623.34 hm2). (2) The analysis of ESV revealed that climate regulation, hydrology regulation, and waste treatment were the three main contributors to ESV in the study area. High-value areas increased in value, low-value areas gradually became high-value areas, and ESV increased overall in the lower reaches of the typical Konqi River Basin. (3) Forest was the land type with the highest ESV in the typical river section of the Konqi River (19,194.25 and 27,532.10 per ten thousand Yuan (CNY) in 2013 and 2020), and its area share change had a significant impact on the overall ESV in the study area. (4) The ESV in the study area showed significant spatial correlations in both the upper and lower reaches according to the Moran index. Hot spot analysis revealed that the hot spot areas in the upper and lower reaches of the study area showed an overall increase and aggregated distribution from 2013 to 2020. Based on these findings, we can infer that oasis towns and surrounding cropland areas in the upper reaches of the study region are not only the areas with the most frequent human activities but also the main source of ecological benefits and the source of human influence on environmental changes. The lower reaches’ ecological benefits are mainly derived from green space. Therefore, to enhance the ecological environment in the typical Konqi River Basin, proper land use planning schemes must be formulated, and each land type area should be strictly protected and monitored. Moreover, pollution prevention and control should be improved, comprehensive environmental management strengthened, relevant laws and regulations improved, and sound management systems implemented. Lastly, public awareness of the development of an ecological civilization should be strengthened to achieve long-term sustainable development in the region.