Understanding the environmental drivers of summer dissolved carbon in lakes on the Qinghai-Tibetan Plateau.

How environmental factors affecting dissolved carbon remains unclear in lakes on the Qinghai-Tibetan Plateau (QTP), which limits the understanding of the lake carbon cycle. In this study, 60 lakes on the QTP in summer were investigated to clarify the variation in dissolved carbon, estimate dissolved carbon storage, and reveal how environmental factors affect the variation in dissolved carbon. The average dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) contents of 60 lakes on the QTP in summer were 12.

Understanding the Asian water tower requires a redesigned precipitation observation strategy.

The Asian water tower (AWT) serves as the source of 10 major Asian river systems and supports the lives of ~2 billion people. Obtaining reliable precipitation data over the AWT is a prerequisite for understanding the water cycle within this pivotal region. Here, we quantitatively reveal that the "observed" precipitation over the AWT is considerably underestimated in view of observational evidence from three water cycle components, namely, evapotranspiration, runoff, and accumulated snow.

A global meta-analysis on the drivers of salt marsh planting success and implications for ecosystem services.

Planting has been widely adopted to battle the loss of salt marshes and to establish living shorelines. However, the drivers of success in salt marsh planting and their ecological effects are poorly understood at the global scale. Here, we assemble a global database, encompassing 22,074 observations reported in 210 studies, to examine the drivers and impacts of salt marsh planting.

Sediment reduction in the middle Yellow River basin over the past six decades: Attribution, sustainability, and implications.

Understanding the underlying driving forces causing changes in sediment yield is crucial for decision-making and major strategy development for the management of the middle Yellow River basin (MYRB). In this work, we quantified the causes of sediment yield reduction in the MYRB and investigated the sustainability of sediment reduction strategies. The sediment yield in the middle Yellow River during 1957-2017 exhibits a significant downward trend.

High-quality reconstruction of China's natural streamflow.

Reconstruction of natural streamflow is fundamental to the sustainable management of water resources. In China, previous reconstructions from sparse and poor-quality gauge measurements have led to large biases in simulation of the interannual and seasonal variability of natural flows. Here we use a well-trained and tested land surface model coupled to a routing model with flow direction correction to reconstruct the first high-quality gauge-based natural streamflow dataset for China, covering all its 330 catchments during the period from 1961 to 2018.

Full-stream erosion in the lower Yellow River: Feasibility, sustainability and opportunity.

The issue of how to achieve removal of recently accumulated sediment is one of the largest unresolved puzzles in China's lower Yellow River. In this work, the feasibility and sustainability of achieving full-stream erosion in the lower Yellow River based on a water-sediment regulation scheme (WSRS) have been comprehensively investigated. The results indicate that the erosion-deposition state of the lower Yellow River is controlled by the incoming flow discharge level and the corresponding sediment concentration.

Long-term trends in Songhua River Basin streamflow and its multivariate relationships with meteorological factors.

Long-term streamflow trends are closely related to meteorological factors; understanding the relationships between them helps to improve water resources management in advance. In this study, we examined long-term annual and seasonal streamflow trends over 1961-2010 in 28 stations in the Songhua River Basin (SRB), China, using four kinds of trend detection methods and then determined the optimal meteorological predictors for SRB streamflow based on the multiple wavelet coherence. We found significant downward trends in annual streamflow in a large part of the study stations (varies from 10 to 18 for different methods), and fewer decreasing stations were detected when we consider the full autocorrelation and the long-term persistence in streamflow.

Global Observations and CMIP6 Simulations of Compound Extremes of Monthly Temperature and Precipitation.

Compound climate extremes, such as events with concurrent temperature and precipitation extremes, have significant impacts on the health of humans and ecosystems. This paper aims to analyze temporal and spatial characteristics of compound extremes of monthly temperature and precipitation, evaluate the performance of the sixth phase of the Coupled Model Intercomparison Project (CMIP6) models in simulating compound extremes, and investigate their future changes under Shared Socioeconomic Pathways (SSPs). The results show a significant increase in the frequency of compound warm extremes (warm/dry and warm/wet) but a decrease in compound cold extremes (cold/dry and cold/wet) during 1985-2014 relative to 1955-1984.

Soil erosion modelling: A bibliometric analysis.

Soil erosion can present a major threat to agriculture due to loss of soil, nutrients, and organic carbon. Therefore, soil erosion modelling is one of the steps used to plan suitable soil protection measures and detect erosion hotspots. A bibliometric analysis of this topic can reveal research patterns and soil erosion modelling characteristics that can help identify steps needed to enhance the research conducted in this field.

Time lag of vegetation growth on the Loess Plateau in response to climate factors: Estimation, distribution, and influence.

Vegetation growth is importantly affected by seasonal weather patterns. The time lag between changes in these patterns and the vegetative response is an important factor in vegetation-climate interactions and can vary considerably with the spatial heterogeneity of an ecosystem. In this study of the Loess Plateau, China, highly accurate time lags were determined at the daily scale using linear regression based on a multiyear normalized difference vegetation index (NDVI) dataset (1982-2015) and the corresponding reconstructed monthly climate series.

Human activities aggravate nitrogen-deposition pollution to inland water over China.

In the past three decades, China has built more than 87 000 dams with a storage capacity of ≈6560 km and the total surface area of inland water has increased by 6672 km. Leaching of N from fertilized soils to rivers is the main source of N pollution in China, but the exposure of a growing inland water area to direct atmospheric N deposition and N leaching caused by N deposition on the terrestrial ecosystem, together with increased N deposition and decreased N flow, also tends to raise N concentrations in most inland waters. The contribution of this previously ignored source of  N deposition to freshwaters is estimated in this study, as well as mitigation strategies.

Homogenization and polarization of the seasonal water discharge of global rivers in response to climatic and anthropogenic effects.

We investigate global trends in seasonal water discharge using data from 5668 hydrological stations in catchments whose total drainage area accounts for 2/3 of the Earth's total land area. Homogenization of water discharge, which occurs when the gap in water discharge between dry and flood seasons shrinks significantly, affects catchments occupying 2/5 of the total land area, and is mainly concentrated in Eurasia and North America. By contrast, polarization of water discharge, associated with widening of the gap in water discharge between dry and flood seasons, occurs in catchments covering 1/6 of the land area, most notably in the Amazon Basin and river basins in West Africa.

Global heat stress on health, wildfires, and agricultural crops under different levels of climate warming.

The effects of heat stress are spatially heterogeneous owing to local variations in climate response, population density, and social conditions. Using global climate and impact models from the Inter-Sectoral Impact Model Intercomparison Project, our analysis shows that the frequency and intensity of heat events increase, especially in tropical regions (geographic perspective) and developing countries (national perspective), even with global warming held to the 1.5 °C target.

Temporal and spatial variations in water discharge and sediment load on the Loess Plateau, China: A high-density study.

Over the past 50 years, a series of soil and water conservation measures have been implemented on the Loess Plateau, including biological, engineering, and agricultural measures. As a result, water discharge and sediment load on the plateau have undergone significant changes. In this study, we compared the water discharge and sediment load at >100 hydrological stations across the Loess Plateau during the period 2008-2016 (P2) with the water discharge and sediment load during the period 1971-1987 (P1), and detected the main sources of sediment in each of the two periods.

Spatiotemporal variations in vegetation cover on the Loess Plateau, China, between 1982 and 2013: possible causes and potential impacts.

Vegetation is a key component of the ecosystem and plays an important role in water retention and resistance to soil erosion. In this study, we used a multiyear normalized difference vegetation index (NDVI) dataset (1982-2013) and corresponding datasets for observed climatic variables to analyze changes in the NDVI at both temporal and spatial scales. The relationships between NDVI, climate change, and human activities were also investigated.

Detecting the quantitative hydrological response to changes in climate and human activities.

Understanding the relative contributions of climate change and human activities to changes in runoff is important for sustainable management of regional water resources. In this study, we systematically review ten commonly used quantitative methods drawn from three main categories-empirical statistics, elasticity-based methods, and hydrological modeling. We explain the calculation processes for the different methods and summarize their applications and characteristics.

Environmental impact assessments of the Xiaolangdi Reservoir on the most hyperconcentrated laden river, Yellow River, China.

The Yellow River is the most hyperconcentrated sediment-laden river in the world. Throughout recorded history, the Lower Yellow River (LYR) experienced many catastrophic flood and drought events. To regulate the LYR, a reservoir was constructed at Xiaolangdi that became operational in the early 2000s.

Linkage Between Hourly Precipitation Events and Atmospheric Temperature Changes over China during the Warm Season.

We investigated changes in the temporospatial features of hourly precipitation during the warm season over mainland China. The frequency and amount of hourly precipitation displayed latitudinal zonation, especially for light and moderate precipitation, which showed successive downward change over time in northeastern and southern China. Changes in the precipitation amount resulted mainly from changes in frequency rather than changes in intensity.

Functional degradation of the water-sediment regulation scheme in the lower Yellow River: Spatial and temporal analyses.

Heavy sedimentation has led to the phenomenon of a secondary perched river in the lower reaches of the Yellow River. The water-sediment regulation scheme (WSRS) using the Xiaolangdi Reservoir was first implemented in 2002 to try to solve this problem. In this study, we analyzed the spatial and temporal effects of the current WSRS (2005-2013) on the lower Yellow River.

Variations in global temperature and precipitation for the period of 1948 to 2010.

Climate change has impacts on both natural and human systems. Accurate information regarding variations in precipitation and temperature is essential for identifying and understanding these potential impacts. This research applied Mann-Kendall, rescaled range analysis and wave transform methods to analyze the trends and periodic properties of global and regional surface air temperature (SAT) and precipitation (PR) over the period of 1948 to 2010.

Trend, abrupt change, and periodicity of streamflow in the mainstream of Yellow River.

The Yellow River is the second largest river in China. The annual runoff of which is only about 2% of China's total, but contributes to 9% of China's GDP and directly supports 12% of the population. Today, the water shortage in the Yellow River basin has been aggravated due to rapid population growth and global warming.