Haisheng Cai

Watershed management is an ever-evolving practice involving the management of land, water, biota, and other resources in a defined area for ecological, social, and economic purposes. In this paper, we explore the following questions: How has watershed management evolved? What new tools are available and how can they be integrated into sustainable watershed management? To address these questions, we discuss the process of developing integrated watershed management strategies for sustainable management through the incorporation of adaptive management techniques and traditional ecological knowledge. We address the numerous benefits from integration across disciplines and jurisdictional boundaries, as well as the incorporation of technological advancements, such as remote sensing, GIS, big data, and multi-level social-ecological systems analysis, into watershed management strategies. We use three case studies from China, Europe, and Canada to review the success and failure of integrated watershed management in addressing different ecological, social, and economic dilemmas in geographically diverse locations. Although progress has been made in watershed management strategies, there are still numerous issues impeding successful management outcomes; many of which can be remedied through holistic management approaches, incorporation of cutting-edge science and technology, and cross-jurisdictional coordination. We conclude by highlighting that future watershed management will need to account for climate change impacts by employing technological advancements and holistic, cross-disciplinary approaches to ensure watersheds continue to serve their ecological, social, and economic functions. We present three case studies in this paper as a valuable resource for scientists, resource managers, government agencies, and other stakeholders aiming to improve integrated watershed management strategies and more efficiently and successfully achieve ecological and socio-economic management objectives.

Abstract Changes in human-dominated spatial patterns of land use are the main driving factors of water quality evolution in watersheds, and the quantitative impact of land use changes on water quality is currently a focus of lake ecology research. Using the Junshan Lake Basin as a study area, this paper quantitatively analyzes the response relationships between the water quality parameters, land use, and socio-economic factors in the study area from 2005 to 2019 and predicts the water quality in 2035 based on land and space planning scenarios. The results show the following. (1) The land use structure of the Junshan Lake Basin has changed significantly over the last 15 years. The basic trend is an increase in settlement and wetland areas in the basin and a decrease in water, cropland, forest, and grassland areas. (2) Settlement areas play the role of a ‘source’ for the total phosphorus (TP) and ammonium-nitrogen (NH3-N) pollution load, and cropland areas play the role of a ‘sink’ for the TP, NH3-N, and chemical oxygen demand (CODMn) pollution load. (3) The main land use type in the Junshan Lake Basin is cropland, which accounts for more than 40% of the total, and the water quality in the lake is affected not only by non-point source pollution but also by the regional Gross Domestic Product (GDP), total population, and per capita disposable income. According to the water quality prediction and analysis, the concentrations of TN and TP in Junshan Lake will meet the Class IV water quality standard in 2035, and the concentrations of dissolved oxygen (DO) and CODMn will meet the Class II standard. This study is significant for the management and control of the water environment in the Junshan Lake Basin.

With the intensification of socioeconomic activities and climate change, land use conflicts are becoming more and more serious, posing major obstacles to the sustainable use of territorial space. This study conducted research on land use conflict and zoning control with a view to contributing new ideas for the prevention and resolution of land use risks. By analyzing the positioning and drawing upon fundamental theories, a novel research paradigm was proposed. An empirical study was conducted in the Gan River Basin in Jiangxi Province by applying the comprehensive evaluation method and geographical detector, and the basin was divided into six types of zones according to the intensity of land use conflict and the hierarchy of ecosystem service values. The results of the empirical study showed that the areas of intense conflict, low conflict and weak conflict accounted for 1.57%, 29.16% and 69.26% of the basin area, respectively. Of the intense conflict areas, 4.42% of the areas in the lower Gan River Basin were in intense conflict, while only 0.37% of the right bank of the middle reaches was in intense conflict. The driving factor analysis showed that precipitation, the population density and policy planning had a greater influence on land use conflict and that land use conflict was more likely to occur with the interaction of precipitation and the nighttime light index, population density and NDVI. The superimposed image analysis revealed that the land use conflict was intense at the junctions of urban areas and cropland and at the junctions of cropland and forests in the middle and upper reaches of the basin, which were mainly caused by the demand for urban expansion and the spread of agricultural production areas. The results of this empirical study are in agreement with the actual situation in the Gan River Basin, proving that the research paradigm proposed in this study is scientific and applicable. Moreover, we emphasize that this paradigm can be adapted in its application according to different research objects and continuously improved in response to the evolution of the territorial spatial management system. This study is of positive significance for the implementation of territorial spatial planning and provides a scientific basis for the further enhancement of the system of territorial spatial governance.

Throughout human history, human activities have resulted in land use and land cover changes (LUCC) and can have a direct impact on the land surface thermal environment (LSTE). In the existing studies, the holistic nature of changes in land use and land cover (LULC) has been neglected in favor of focusing on the interactions between different LULC types and the land surface thermal environment. This study used ArcGIS Pro 3.0, ENVI 5.3, and SPSS software to construct a contribution index model and stepwise regression equation to investigate the relationship between LULC type, structure, and pattern changes and LSTE changes in Nanchang City, Jiangxi Province, China, from 1990 to 2020. The findings revealed that 1) rapid urbanization has led to a surge in the area of built-up land and a decrease in the area of arable land in Nanchang; between 1990 and 2020, the area of built-up land in Nanchang increased by 433.29 km 2 , while the area of arable land decreased by 291.99 km 2 ; 2) The land surface temperature (LST) was divided into five classes according to the equal spacing method, and the areas with the highest and lowest temperature classes were the high temperature zone and the low temperature zone, respectively. Over the past 30 years, the LSTE in Nanchang has gradually deteriorated, with the area of the low temperature zone shrinking by 554.2 km 2 and the area of other classes appearing to increase significantly; 3) the contribution index and stepwise regression equation demonstrate that the primary reasons for the worsening of the LSTE are an increase in the scale of cultivated land and construction land. It was found that rationalization of urban LULC type, structure, and pattern can effectively reduce land surface temperature.

<bold>Objective</bold> To quantify the spatiotemporal response of ecosystem services to land use change in Ganzhou City and analyze their trade-off and synergy relationships，providing reference for optimizing the national land space，constructing an ecological security pattern，and achieving sustainable development in Ganzhou City. <bold>Method</bold> Based on remote sensing data in 2005，2015 and 2023，the InVEST model was used to evaluate the habitat quality，water yield，soil conservation，and carbon storage in Ganzhou City and hotspot analysis method was used to analyze changes in ecosystem services.Pearson correlation coefficient，trade-off synergy and contrastive analysis approach were used to the trade-off and synergy relationships among ecosystem services，and the reasons were analyzed from the perspective of land use change. <bold>Result</bold> （1）The land structure in Ganzhou City is dominated by forest land，accounting for over 74%.The construction land increased the most from 2005 to 2023，reaching 330.94 km² with a dynamic degree of 4.83%；From 2005 to 2015，59.68 km² of forest land was transferred to other types of land use annually；The cultivated land increased by 34.41 km² annually from 2015 to 2023.（2）From 2005 to 2023，the habitat quality，water production，soil conservation，and carbon storage in Ganzhou City have decreased by 0.000 2，3.170 7 mm，21.893 0 t/km² and 5.154 7 t/km² annually.There are differences in spatial distribution among the four ecosystem services.The area of hotspots in categories 1，2 and 3 accounts for about 90% of the total area.（3）The ecosystem services in Ganzhou City mainly had a synergy relationship，but also had little differences.The trade-offs and synergy relationships among ecosystem services in different time sections are the same，while those among ecosystem services in different time periods may not be the same.（4）The composition of ecosystem services in the same land use type is basically stable，while different land use changes have different impacts on ecosystem services.For example，the conversion between construction land and forest land has the greatest impact on carbon storage. <bold>Conclusion</bold> The land use change in Ganzhou City is the core driving factor for the evolution of the spatial pattern of ecosystem services，and the resulting trade-offs and synergies between services reflect the inherent tension between land development and ecological protection.To achieve regional sustainable development，it is necessary to go beyond the contradictory thinking of development and protection，taking the above laws as the scientific basis for spatial control，promoting the region towards high-quality development through optimizing the national spatial pattern.