Shaofeng Jia

Reliable long-term monitoring of ecological quality is essential for assessing progress toward the Sustainable Development Goals (SDGs) in fragile alpine regions, yet remote-sensing assessments often assume that factors explaining spatial patterns also drive temporal change. We tested this assumption in Sanjiangyuan, the headwater region of the Yangtze, Yellow and Lancang–Mekong rivers, using annual Landsat composites (1986–2024) and a modified remote sensing ecological index (MRSEI) with fixed normalization across years. We combined trend and class-centroid analyses with GeoDetector, variation partitioning, spatial-block cross-validation and pixel-level detrended correlations. Regional mean MRSEI increased significantly (0.0245 per decade); improving trends covered 78.1% of the valid area, including 36.6% with statistically significant improvement. A conventional RSEI showed the same direction but a steeper slope, and MRSEI agreed spatially with MODIS LAI and NPP (median r = 0.83 and 0.73). Good- and excellent-class centroids shifted northwestward by 56.08 and 20.51 km. Natural factors uniquely explained 41.81–54.41% of spatial variance and the human footprint only 0.02–0.59%, with negligible out-of-block predictive gain. Temporally, MRSEI anomalies were consistently associated with precipitation and soil moisture over 1986–2024, whereas the air-temperature association was weak and sampling-sensitive, and human-footprint associations were near zero. Spatial dominance therefore does not imply temporal control, and the fixed negative thermal direction of RSEI-type indices warrants testing in cold regions. These findings support the sustainable management of China’s Water Tower through targeted verification of degrading areas, drought-sensitive early warning and the monitoring of land degradation neutrality (SDG 15.3).

Spatial heterogeneity in economic benefits of water use provides crucial evidence for the evaluation of water diversion projects and the spatial equilibrium of water resource allocation. Using city-level data from 2017 on the sectoral water use and value added in 334 Chinese cities, we estimated the economic benefits of water use in the agricultural, industrial, and service sectors using the allocation coefficient method. We then revealed the spatial heterogeneity combining an exploratory spatial data analysis (ESDA) method. For the agricultural sector, the high economic benefit of water use regions are primarily concentrated on both sides of the “Hu Huanyong Line”; regions with high economic benefit of industrial water use are mainly found in the North China Plain, the middle and lower Huanghe River basin, the Yangtze River Delta, the Pearl River Delta, Chongqing and Chengdu, and the economic benefit of service water use is higher in the north than in the south. ESDA provides significant evidence for the analysis of spatial heterogeneity with regard to the economic benefits of water use in China. Based on the fundamental distribution of water resources and the spatial heterogeneity in the economic benefits of water use, potential water diversion areas can be preliminarily identified. The Haihe River Basin in the North China Plain and some areas in the southeast coastal region are potential receiving areas, and the eastern regions of Southwest China with abundant water resources and lower elevations, along with the middle and lower reaches of the Yangtze River are potential source areas. Further research about marginal benefits and water use costs, along with dynamic updates, is required for water resource allocation of China.

Under global environmental change, the health of rivers and lakes on the “Asian Water Tower”—the Qinghai–Tibetan Plateau—is facing mounting pressures. This study examines Qinghai Lake, the Huangshui River, the Golmud River, and the Qinghai reach of the Yangtze River. By integrating the Water Quality Index (WQI) with the AHP–TOPSIS framework, we develop a multidimensional assessment system encompassing water resources, water environment, aquatic ecology, and management functions. The WQI results reveal pronounced spatial heterogeneity in water quality, with conditions ranked as Golmud River > Yangtze River > Huangshui River > Qinghai Lake. Dominant controlling factors also shift from dissolved oxygen in riverine systems to total phosphorus in the lake environment. The comprehensive AHP–TOPSIS evaluation further shows a health ranking of Yangtze River (0.736) > Golmud River (0.602) > Qinghai Lake (0.404) > Huangshui River (0.297), leading to the identification of four distinct management pathways: ecological conservation, natural restoration, nutrient control, and pollution remediation. By moving beyond single-parameter diagnostics, this study provides a robust methodological basis for differentiated river–lake management. The proposed “one river (lake), one strategy” framework, coupled with red-line management recommendations grounded in key indicators, offers direct scientific support for systematic protection and precise governance of aquatic ecosystems on the Qinghai–Tibetan Plateau, contributing to national ecological security and high-level environmental stewardship.

Spatial heterogeneity in economic benefits of water use provides crucial evidence for the evaluation of water diversion projects and the spatial equilibrium of water resource allocation. However, research focusing on the economic benefits of water use in major industries within Chinese cities remains insufficient. We collected water use and value added data of agriculture, industry, and service sectors of 334 Chinese cities in 2017, and used the benefit allocation coefficient method to calculated the economic benefit of water use in the three sectors. Then we analyzed spatial heterogeneity in the economic benefits of water use: for agricultural sector, the high economic benefit of water use regions are primarily concentrated on both sides surrounding of the “Hu Huanyong Line”; regions with high economic benefit of industrial water use are mainly found in the North China Plain, the middle and lower Huanghe River basin, the Yangtze River Delta, the Pearl River Delta, Chongqing and Chengdu; and the economic benefit of service water use is higher in the north than in the south. Based on the fundamental distribution of water resources and the spatial heterogeneity in the economic benefits of water use, potential water diversion areas can be preliminarily identified: the Haihe River Basin in the North China Plain and some areas in the southeast coastal region are potential receiving areas, and the eastern regions of Southwest China with abundant water resources and lower elevations, along with the middle and lower reaches of the Yangtze River are potential source areas. Further research about marginal benefits and water use costs, along with dynamic updates, is required for water resource allocation of China.

There is a broad consensus that an ensemble of global climate models (GCMs) generally outperforms individual models and is, therefore, preferred in water resources’ impact assessment studies for better planning and management. However, the reliability of future projections depends on the historical performance of these models. This study first aimed to evaluate the performance of different GCMs’ ensembles by simulating streamflow and, second, to develop a new ensemble framework for improved hydrologic simulation. We used daily precipitation and temperature data (1931–2012) of all available GCMs from the Coupled Model Intercomparison Project phase 6. Six datasets were created from a best-performing GCM, five top-ranked GCMs, and all available GCMs, both with and without bias correction (BC). These datasets were evaluated by simulating streamflow with a hydrological model at different hydrometric stations in the Amudarya River basin, which shares the borders of Afghanistan, Tajikistan, Kyrgyzstan, Turkmenistan, and Uzbekistan. Initial simulations using these conventional ensembles—both raw and bias-corrected—showed poor performance, with Nash–Sutcliffe efficiency E values often below 0.50 and underestimation of peak flows. To address this, we proposed a multimodel ensemble using a ranking-based weighted mean of bias-corrected GCMs, further disaggregating into a daily scale using a weather generator. This approach demonstrated substantial improvements in streamflow simulation, increasing E and correlations by up to 0.72 and 0.85, respectively, on average, and a more accurate reproduction of extreme flows. So the proposed framework can be used with confidence in simulating hydrological processes, particularly for extreme events.

The North China Plain is a crucial agricultural region in China, but irregular precipitation patterns have led to significant water shortages. To address this, analyzing the high-resolution dynamics of root-zone soil moisture transport is essential for optimizing irrigation strategies and improving water resource efficiency. The Richards equation is a robust model for describing soil moisture transport dynamics across multiple soil layers, yet its application at large spatial scales is hindered by its sensitivity to boundary conditions and model parameters. This study introduces a novel approach that, for the first time, employs a continuous time series of near-surface soil moisture as the upper boundary condition in the Richards equation to estimate high-resolution root-zone soil moisture in the North China Plain, thus enabling its large-scale application. Singular spectrum analysis (SSA) was first applied to reconstruct site-specific time series, filling in missing and singular values. Leveraging observational data from 617 monitoring sites across the North China Plain and multiple spatial covariates, we developed a machine learning model to estimate near-surface soil moisture at a 1 km resolution. This high-resolution, continuous near-surface soil moisture series then served as the upper boundary condition for the Richards equation, facilitating the estimation of root-zone soil moisture across the region. The results indicated that the machine learning model achieved a correlation coefficient (R) of 0.92 for estimating spatial near-surface soil moisture. Analysis of spatial covariates showed that atmospheric forcing factors, particularly temperature and evaporation, had the most substantial impact on model performance, followed by static factors such as latitude, longitude, and soil texture. With a continuous time series of near-surface soil moisture, the Richards equation method accurately predicted multi-layer soil moisture and demonstrated its applicability for large-scale spatial use. The model yielded R values of 0.97, 0.78, 0.618, and 0.43, with RMSEs of 0.024, 0.06, 0.08, and 0.11, respectively, for soil layers at depths of 10 cm, 20 cm, 40 cm, and 100 cm across the North China Plain.

The Qaidam Basin in China, recognized for its copious salt lake mineral resources, holds immense significance for the nation’s sustenance and industrial progression. However, the escalating exploitation of these resources has led to substantial conflicts between economic pursuits and ecological conservation. Ongoing activities like water diversion for flood control and brine extraction are hindering the preservation of the lake’s natural ecosystem. This study examines the challenges of salt lake exploitation and ecological conservation, proposing measures for environmental stewardship. These include delineating the responsibilities of production zones designated for salt lake development; advocating the comprehensive harnessing of flood resources; and establishing a collaborative platform for integrating ecological data among government entities, regulatory bodies, and private enterprises. This research aims to lay the groundwork for ecological management policies for salt lakes in the Qaidam region to balance the development of a top-tier salt lake production base with environmental preservation.

Integrated River Basin Management (IRBM) involves the integration of the multiple uses of water, the integration of multiple properties of water: water disaster, water resources, waterways, water environment, water ecology, water landscape and water culture, and the integration of water by space: upstream vs downstream, left bank vs right bank. The main problems of IRBM within the Lancang-Mekong River Basin includes flood disaster, navigation and its impact to basin cooperation, contradiction between development and protection, and public security in a framework of cooperation and integration. It has been a general concern for Mekong countries to manage water conservancy engineering and coordinate water supply, navigation, fishery, power generation, and water disaster management. All stakeholders put great emphasis on water conservancy engineering management in terms of basin planning, domestic and cross-border project construction, and cooperation mechanisms. In order to ensure the sustainable use of water resources, a series of continuously updated plans were proposed. Those plans set goals and provided measures for the rational and sustainable development of the resources in the basin, and meanwhile, it also put forward a mechanism to offset the adverse effects. The development of international navigation has deepened win-win cooperation, strengthened regional economic exchanges and tourism development, promoted regional prosperity among China, Laos, Myanmar and Thailand. The basin has abundant fishery resources and has the world’s third most diverse fish population, with 1,148 fish species, after the Amazon and Congo River Basins. Mekong countries have different needs for the development of fishery resources due to their different geographical locations and economic development, and thus very little cooperation in fisheries has been carried out among Mekong countries. The basin’s ecohydrological management involves environmental flow, water quality, soil erosion and sedimentation, aquatic organism and underground water protection. The current measures include enhancing monitoring, scientific assessment, rational regulation of water system, the establishment of natural reserves, and international cooperation. Climate change and construction of dams are both critical challenges faced by the basin in terms of ecohydrological management in the 21st century.

Integrated basin governance means integrated water governance taking basin as the spatial unit. It deals with rules of integrated water resources management, including the establishment of governance bodies, the definition of interests and roles of stakeholders, the principles and regulations of decision-making, and the arrangement of decision-making procedures. For trans-national basins, international cooperation for integrated basin governance is necessary that is mainly embodied by basin cooperation mechanisms. The implementation of international basin cooperation depends on a number of mechanisms. There are about fifteen cooperative mechanisms in the Mekong Region divided into two groups: intra-regional mechanisms (cooperation among Mekong countries) and mechanisms between Mekong countries and non-basin partners. MRC, GMS and LMC are the three most active mechanism. Within the Lancang-Mekong River Basin, each country has particular perspectives about international basin cooperation. China is very active in Basin cooperation and has invested a lot of resource in this regard, but is sensitive to the intervention from countries outside the region. Cambodia and Laos, with most territory located within the Basin and essential or even majority of foreign investment from China, are active to diversify their international cooperation while maintaining close cooperation with China. Most of the inflow of foreign investments into Myanmar comes from Asian countries, followed by European countries and the United States, and is influenced by its domestic political situation. Thailand has been a relatively stable recipient country of foreign investment for a long time and has benefited significantly, it has now become a donor country, playing an important leading role in basin cooperation. Vietnam’s foreign investment mainly comes from Japan, Korea, and ASEAN. Vietnam plays the leading role in environmental cooperation in Lower Mekong Cooperation with the United States, and has actively participated in the “One Decade of Green Mekong” initiative in Mekong-Japan cooperation. Some countries outside the basin, such as the United States, Japan, India, Korea, India and international organizations such as the World Bank and the Asian Development Bank, have significant influence on basin governance. Social participation in Lancang-Mekong River Basin governance plays a very important role. A variety of stakeholders, ranging from global network initiatives to local NGOs, from business enterprises to communities, have been actively engaging in the governance of the Lancang-Mekong River Basin. They have adopted different strategies (e.g., scientific research, capability building, policy advocacy, and citizen engagement) to exert influence on various issues such as climate change, biodiversity, hydropower development, and sustainable livelihood, revealing overlapping and interacting mechanisms of participation. The future trend of basin cooperation is more optimistic along with the consensus strengthening and capacity building, although there may be still some interferent brought by big power competition and interest disputations.