• Energy Research
• environmental engineering close
• 12. Responsible consumption close
• Chinese Academy of Sciences close

Water quality safety has attracted global attention and is closely related to the development of the social economy and human health. It is widely recognized that climate change and human activities significantly affect water quality changes. Therefore, quantifying the contributions of factors that drive long-term water quality changes is crucial for effective water quality management. Here, we built a climate-water quality assessment framework (CWQAF) based on climate-water quality response coefficients and trend analysis methods, to achieve this goal. Our results showed that the water quality improved significantly by 4.45%-20.54% from 2011 to 2020 in the Minjiang River basin (MRB). Human activities (including the construction of ecological projects, stricter discharge measures, etc.) were the main driving factors contributing 65%-77% of the improvement effect. Notably, there were differences in the contributions of human activities to water quality parameter changes, such as DO (increase (I): 0.12 mg/L, human contribution (HC): 66.8%), CODMn (decrease (D): 0.71 mg/L, HC: 67.2%), BOD5 (D: 1.10 mg/L, HC: 77.7%), CODCr (D: 4.20 mg/L, HC: 81.2%), TP (D: 0.13 mg/L,HC: 72.8%) and NH3-N (D: 0.40 mg/L, HC: 63.0%). Climate change explained 23%-35% of the variation in water quality. The water quality response to climate change was relatively significant with precipitation. For example, the downstream region was more susceptible to climate change than was the upstream region, as the downstream movement of precipitation centers strengthened the process of climatic factors affecting water quality changes in the MRB. Generally, although human activities were the main driving factor of water quality changes at the basin scale, the contribution of climate change could not be ignored. This study provided a manageable framework for the quantitative analysis of the influence of human activities and climate change on water quality to enable more precise and effective water quality management.

The Grain to Green Project (GTGP), a large ecological restoration project aiming to control soil erosion and improve the ecological environment, has been implemented since 1999 and has led to great land use changes with decreased farmland and increased forest and grass, and significant vegetation variations. Understanding vegetation variations for different land use types is important for accessing the present vegetation development and providing scientific guidance for future ecological restoration design and regional sustainable development. With two land use maps and MODIS LAI data, trend analysis, fluctuation analysis, and R/S methods were applied to analyze the vegetation dynamic changes and sustainability for converted land use types from cropland and unconverted types over 2000–2015 in the upper and middle reaches of the Yellow River. The results obtained were as follows: (1) Vegetation greening was remarkable in the entire study region (0.036 yr−1). The increasing rate was higher in wetter conditions with AI < 3 (0.036–0.053 yr−1) than arid regions with AI > 3 (0.012–0.024 yr−1). (2) Vegetation improved faster for converted forestland, shrubland, and grassland than unconverted types under similar drying conditions. Converted shrubland and grassland had a larger relative change than converted forestland. (3) Converted land use types generally exhibited stronger fluctuation than unconverted types with small differences among types. (4) Vegetation exhibited a sustainable increasing trend in the future, which accounted for more than 73.1% of the region, mainly distributed in the middle reach of the Yellow River. Vegetation restoration exerted important influences on vegetation greening and the effect was stronger for converted types than unconverted types.

Endorheic basins (i.e., land-locked drainage networks) and their lakes can be highly sensitive to variations in climate and adverse anthropogenic activities, such as overexploitation of water resources. In this review paper, we provide a brief overview of one major endorheic basin on each continent, plus a number of endorheic basins in Central Asia (CA), a region where a large proportion of the land area is within this type of basin. We summarize the effects of (changing) climate drivers and land surface–atmosphere feedbacks on the water balance. For the CA region, we also discuss key anthropogenic activities, related water management approaches and their complex relationship with political and policy issues. In CA a substantial increase in irrigated agriculture coupled with negative climate change impacts have disrupted the fragile water balance for many endorheic basins and their lakes. Transboundary integrated land and water management approaches must be developed to facilitate adequate climate change adaptation and possible mitigation of the adverse anthropogenic influence on endorheic basins in CA. Suitable climate adaptation, mitigation and efficient natural resource management technologies and methods are available, and are developing fast. A number of these are discussed in the paper, but these technologies alone are not sufficient to address pressing water resource issues in CA. Food–water–energy nexus analyses demonstrate that transboundary endorheic basin management requires transformational changes with involvement of all key stakeholders. Regional programs, supported by local governments and international donors, which incorporate advanced adaptation technologies, water resource research and management capacity development, are essential for successful climate change adaptation efforts in CA. However, there is a need for an accelerated uptake of such programs, with an emphasis on unification of approaches, as the pressures resulting from climate change and aggravated by human mismanagement of natural water resources leave very little time for hesitation.

The Loess Plateau, covering approximately 640,000 km2, has experienced the most severe soil erosion in the world. A greening tendency has been noticed since implementing the Grain to Green Program (GTGP), which may prevent further soil erosion. Therefore, understanding the underpinning basis of greening stability and persistence is important for sustainable improvement. Global Inventory Modeling and Mapping Studies (GIMMS) normalized difference vegetation index (NDVI) datasets for 1982–2013 were used to investigate the temporal stability and persistent time (PT) of vegetation over the Loess Plateau, utilizing the coefficient of variation (CV) and the estimation of tendencies of vegetation greening starting from the selected reference conditions. Two periods from 1982 to 1999 (as the reference period) and 2000 to 2013 were selected by considering the GTGP since 1999. The results indicate that: (1) A significant increase in vegetation cover occurred in the low NDVI area (NDVI < 0.3), with a high fluctuation from 2000 to 2013 compared with the reference period. Moreover, the fluctuation in vegetation is more related to precipitation variation since 1999. (2) Most areas recovered in the greening trend of the first period starting in 2009, occurring in 28.7% (2628 of 9148) of the total area. (3) The revegetated areas have a low PT and a high CVvi, that is, the revegetated areas need a long time to recover from disturbances. Therefore, we identify the sensitive areas with PT = 4; further management needs to be implemented for sustainable development in these areas. These results provide a method to quantify the stability and persistence of the complex interactions between vegetation greenness and environmental changes, particularly in fragile areas.

Millions of people in Uzbekistan, Turkmenistan, Tajikistan, and Kyrgyzstan are dependent on the freshwater supply of the Vakhsh River system. Sustainable management of the water resources of the Vakhsh River Basin (VRB) requires comprehensive assessment regarding future climate change and its implications for streamflow. In this study, we assessed the potential impacts of projected climate change scenarios on the streamflow in the VRB for two future periods (2022–2060 and 2061–2099). The probable changes in the regional climate system were assessed using the outputs of five global climate models (GCMs) under two representative concentration pathways (RCPs), RCP4.5 and RCP8.5. The probable streamflow was simulated using a semi-distributed hydrological model, namely the Soil and Water Assessment Tool (SWAT). Evidence of a significant increase in the annual average temperature by the end of the 21st century was found, ranging from 2.25 to 4.40 °C under RCP4.5 and from 4.40 to 6.60 °C under RCP8.5. The results of three GCMs indicated a decreasing tendency of annual average precipitation (from −1.7% to −16.0% under RCP4.5 and from −3.4% to −29.8% under RCP8.5). Under RCP8.5, two GCMs indicated an increase (from 2.3% to 5.3%) in the average annual precipitation by the end of 2099. The simulated results of the hydrological model reported an increasing tendency of average annual streamflow, from 17.5% to 52.3% under both RCPs, by the end of 2099. A shift in the peak flow month was also found, i.e., from July to June, under both RCPs. It is expected that in the future, median and high flows might increase, whereas low flow might decrease by the end of 2099. It is concluded that the future seasonal streamflow in the VRB are highly uncertain due to the probable alterations in temperature and precipitation. The findings of the present study could be useful for understanding the future hydrological behavior of the Vakhsh River, for the planning of sustainable regional irrigation systems in the downstream countries, i.e., Uzbekistan and Turkmenistan, and for the construction of hydropower plants in the upstream countries.

Land use and land cover changes (LULCC) significantly affect the climate at regional and global levels through different biogeophysical and biogeochemical processes. However, the effects of biogeophysical aspects of LULCC on climate have been often ignored, which may overestimate the biogeochemical effects on climate change. Thus, understanding the biogeophysical influence of land use changes on climate change in future potential scenarios is crucial. Therefore, it is necessary to identify the mechanism and land use change impacts on future climate under different scenarios through changes in underlying surface and surface energy balance. In order to fill this research gap, three simulations are performed by Weather Research Forecasting (WRF) model for the year 2010-2030 under Business-As-Usual (BAU) scenario, Rapid Economic Growth (REG) scenario, and Coordinated Environmental Sustainability (CES) scenario to evaluate the influence of future LULCC on temperature projections for the Punjab province in Pakistan. Results show that land use conversions under three scenarios induce overall climate cooling in the region. The decrease in annual average temperature in CES scenario (- 0.02 °C) is slightly greater than that in BAU and REG scenarios (- 0.01 °C). The responses of temperature to future LULCC vary in different months in all scenarios, with greater responses in warmer months, causing climate cooling. In each scenario, the response of temperature is found to be sensitive to different land transitions. The findings of the study can be a reference for policy makers, researchers, and development practitioners in their pursuit to understand the effects of land use change on climate.

This paper develops an integrated modeling approach combined with a top-down dynamic computable general equilibrium (CGE) model and a bottom-up bio-economic model (BEM) to study the economic impact of a total water use control policy in the Heihe river basin, northwestern China. The integrated CGE-BEM model is regionally disaggregated with a variety of crops and livestock, and includes the responses of farmers and consequent feedback effects in the regional economic system. The results show that under the total water use control scenario, the water use structure is changed and water use efficiency is improved. The total water use control policy has limited negative impact on the regional economic growth with only a slightly lower growth rate of 13.38% compared with a growth rate of 14% by 2020 under a business as usual water use scenario. However, the total water use control policy has significant negative impacts on several sectors, especially agriculture and food processing. It is expected cropping systems will change through a replacement of water-intensive crops with water-efficient crops. Farmers’ incomes will decrease by 3.14%. In order to alleviate farmers’ income loss and deal with water use conflicts across different sectors and regions, the promotion of migration of surplus labor from agriculture to non-agricultural sectors and the improvement of water use efficiency in agriculture are needed.