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Fan, A.; Yan, X., and Yin, Q., 2016. A multisource information system for monitoring and improving ship energy efficiency. Global climate change has attracted an increasing amount of attention by the public. The shipping industry is being scrutinized with regard to improving efficiency and reducing emissions. This paper explores the monitoring technology and efficiency enhancement method for a ship. First, the internal and external factors that affect a ship's energy efficiency are determined and examined. Second, an inland river ship is selected as a research target on which a multisource information system is constructed via the selection and installation of the corresponding sensors on the ship. A series of system tests have also been performed when the ship is in operation. The field tests prove that the established system is adequate for the voyage and that all of the sensors can normally monitor the parameters. In addition, a massive quantity of data for the upper, middle, and lower reaches of the Yangtze River are obtained. A grey correlation analysis and regional difference analysis are conducted using these data. The analysis results suggest that the main engine speed has the greatest effect on a ship's fuel consumption and that the voyage environment of the Yangtze River affects a ship's fuel consumption. Finally, a novel ship speed-optimization method that considers the impact of voyage environment is proposed as an energy efficiency enhancement example. This study not only aids shipping companies and ship officers in monitoring a ship's operations but also provides a high-energy efficiency strategy for a ship's operation. [ABSTRACT FROM AUTHOR]

The source region of the Yangtze River is in the hinterland of the Qinghai-Tibet Plateau. The source region is of great ecological significance to Qinghai-Tibet Plateau, and it is praised as the resources bank of biological species. The ecological environment in the source region of Yangtze River has deteriorated during the past decades. Based on land ecological classification and field investigation, two-phase Landsat TM/ ETM remote sensing data obtained in 1995 and 2010 were compared. The spatial changes and dynamic transfers of land ecotypes in the source region were analysed in this paper by using the analytical methods. Results show that the environmental problems in the source region have been caused by the global climate changes and human activities, coupled with the harsh natural conditions and a fragile ecological system. These changes also affect the water environment and the social-economic development of the river basins. There is an urgent need to study possible rehabilitation measures for the eco-environment of the region so as to ensure a sustainable larger river discharge. [ABSTRACT FROM AUTHOR]

Runoffs in the Yellow River and Yangtze River basins, China, have been changing constantly during the last half century. In this paper, data from eight river gauging stations and 529 meteorological stations, inside and adjacent to the study basins, were analyzed and compared to quantify the hydrological processes involved, and to evaluate the role of human activities in changing river discharges. The Inverse Distance Weighted (IDW) interpolation method was used to obtain climatic data coverage from station observations. According to the runoff coefficient equation, the effect of human activities and climate can be expressed by changes in runoff coefficients and changes in precipitation, respectively. Annual runoff coefficients were calculated for the period 1950-2008, according to the correlation between respective hydrological series and regional precipitation. Annual precipitation showed no obvious trend in the upper reaches of the Yellow River but a marked downward trend in the middle and downstream reaches, with declines of 8.8 and 9.8 mm/10 a, respectively. All annual runoff series for the Yellow River basin showed a significant downward trend. Runoff declined by about 7.8 mm/10 a at Sanmenxia and 10.8 mm/10 a at Lijin. The series results indicated that an abrupt change occurred in the late 1980s to early 1990s. The trend of correlations between annual runoff and precipitation decreased significantly at the Yellow River stations, with rates ranging from 0.013/10 a to 0.019/10 a. For the hydrologic series, all precipitation series showed a downward trend in the Yangtze River basin with declines ranging from about 24.7 mm/10 a at Cuntan to 18.2 mm/10 a at Datong. Annual runoff series for the upper reaches of the Yangtze River decreased significantly, at rates ranging from 9.9 to 7.2 mm/10 a. In the middle and lower reaches, the runoff series showed no significant trend, with rates of change ranging from 2.1 to 2.9 mm/10 a. Human activities had the greatest influence on changes in the hydrological series of runoff, regardless of whether the effect was negative or positive. During 1970-2008, human activities contributed to 83% of the reduction in runoff in the Yellow River basin, and to 71% of the increase in runoff in the Yangtze River basin. Moreover, the impacts of human activities across the entire basin increased over time. In the 2000s, the impact of human activities exceeded that of climate change and was responsible for 84% of the decrease and 73% of the increase in runoff in the Yellow River and Yangtze River basins, respectively. The average annual runoff from 1980 to 2008 fell by about 97%, 83%, 83%, and 91%, compared with 1951-1969, at the Yellow River stations Lanzhou, Sanmenxia, Huayuankou and Lijin, respectively. Most of the reduction in runoff was caused by human activities. Changes in precipitation also caused reductions in runoff of about 3%, 17%, 17%, and 9% at these four stations, respectively. Falling precipitation rates were the main explanation for runoff changes at the Yangtze River stations Cuntan, Yichang, Hankou, and Datong, causing reductions in runoff of 89%, 74%, 43%, and 35%, respectively. Underlying surface changes caused decreases in runoff in the Yellow River basin and increases in runoff in the Yangtze River basin. Runoff decreased in arid areas as a result of increased water usage, but increased in humid and sub-humid areas as a result of land reclamation and mass urbanization leading to decreases in evaporation and infiltration. [ABSTRACT FROM AUTHOR]

The vast Dongting Lake in the middle Yangtze River basin, China, was occupied by Chinese Neolithic settlements starting 10 000 years ago, and rice cultivation there is probably the earliest in the world. The numerous Neolithic settlements identified by previous archaeological surveys represent the five major Neolithic cultural stages, i.e. the Pengtoushan (9000–7900 cal. yr BP), Zaoshixiaceng (7900–6800 cal. yr BP), Daxi (6800–5500 cal. yr BP), Qujialing (5500–5000 cal. yr BP), and Shijiahe (5000–4000 cal. yr BP). Using sedimentological and geoarchaeological approaches, this paper analyses the drivers of basin-scale settlement relocation in relation to lake-level fluctuations and monsoon climate variations in the Holocene. The relocation of Neolithic sites around the lake shoreline and on the adjacent floodplain, together with radiocarbon-dated stratigraphy, clearly indicates that the shape of the lake basin was an incised and elongated valley occupied by a lake in the early Holocene, which became a broader and shallower depression in the mid to late Holocene. The established lowest habitable base of the settlements positioned on the lake shore assists reconstruction of the change in lake level from 22 m at 9000 cal. yr BP to 26 m at 5500–4000 cal. yr BP, although higher and lower lake levels occurred during the intervening cultural stages. The pollen spectra reveal a warming trend throughout the Holocene with at least four major temperature cycles, driven by monsoon variations between temperate- and warm-humid conditions. In the early Holocene the climate changed from cool-dry to warm-humid, and this played a key role in developing the earliest Pengtoushan culture in the region. Subsequent climate fluctuations fit well with the advance and retreat of the lake shore, also coevally with Neolithic site movements in the lake region. In this study we show how geoarchaeological evidence can be used in environmental reconstruction during the Holocene. [ABSTRACT FROM AUTHOR]

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Abstract: Extensive research into the changing sediment load throughout the Yangtze River (Changjiang) basin has been completed over recent years, and it provides an ongoing example of how to evaluate the consequences of natural and anthropogenic impacts on sediment processing in a very large fluvial system. This paper reviews these recent studies and critically assesses their findings regarding changes in sediment yield, load (both spatial and temporal variations), grain size, and rating curves, as well as the morphodynamic response of the channel and delta. We also discuss the factors driving these changes, including climate change, soil and water conservation measures, dam construction, and sand extraction, and consider the likely future trends in sediment load. Based on a consideration of the major outcomes of, and discrepancies between, recent studies, we conclude that sediment supply, transport, mobilization, and deposition in this large river system are complicated by the heterogeneous nature of its morphology and climate, as well as the progressive intensification of human activities. Therefore, the identification and interpretation of hydrological and sedimentological changes in the Yangtze basin can be difficult, and an in-depth study of the causal mechanisms of variations in sediment load and the impacts on the Yangtze River system is urgently required. [Copyright &y& Elsevier]

Our knowledge of fundamental drivers of terrestrial net primary production (NPP) is crucial for improving the predictability of ecosystem stability under global climate change. However, the patterns and determinants of NPP are not fully understood, especially in the riparian zone ecosystem disturbed by periodic drought–rewetting (DRW) cycles. The environmental (flooding time, pH, moisture, and clay content) and nutritional properties (soil organic carbon, total nitrogen, total phosphorus, ammonium (NH4+‐N), nitrate (NO3‐‐N), and C:N:P stoichiometry) were investigated in the riparian zone of Pengxi River‐a typical tributary of Three Gorges Reservoir (TGR). Structure equation modeling was performed to evaluate the relative importance of environmental and nutritional properties on NPP of Cynodon dactylon (Linn.) Pers (C. dactylon)‐a dominating plant in the riparian zone of TGR. Our results indicated that NPP was much lower under much severe flooding stress. All of these variables could predict 46% of the NPP variance. Nutrient use efficiency (NUE) was one of the most critical predictor shaping the change of NPP. Specifically, flooding stress as a major driver had a direct positive effect on soil moisture and soil clay content. The soil clay content positively affects the soil C: N ratio, which further had an indirect negative impact on NPP by mediating NUE. Overall, our study provided a comprehensive analysis of the effects of the combined effect of environmental and nutrient factors on NPP and showed that continuous DRW cycles induced by hydrological regime stimulate the decrease of NPP of C. dactylon by changing NUE strategies. Further research is needed to explore the responses of NPP and NUE under different land use to DRW cycles and to investigate the DRW effects on the combined effect of environmental and nutrient factors by in situ experiments and long‐term studies. [ABSTRACT FROM AUTHOR]

Poyang Lake, directly connected with the Yangtze River, is one of the most frequently flooded areas in China. The frequent large floods have caused huge damages to the environment and economy and threatened the life of approximately 10 million people. Understanding the changing characteristics of floods as well as the affecting factors is an important prerequisite of flood disaster prevention and mitigation. In this study, the characteristics of historical floods in Poyang Lake were identified and examined based on several widely used indices and Mann-Kendall test. The study also analyzed the related driving forces and discussed their relationships with Poyang Lake floods. The results show that the floods in Poyang Lake mainly occurred in mid- and late July. The inter-annual variation of highest flood stages and duration showed a long-term increasing linear trend. Also, a slightly increasing linear trend in the timing of highest stages indicated the floods have occurred later and later during the last 60 years. At the decadal scale, the flood situations were most severe in 1990s while gentle in 2000s in terms of the occurrence frequency and average duration. The climate change was the primary influence factor for changing of flood characteristics in Poyang Lake; i.e., the abnormally large rainfall during the flood season and subsequent large discharges of Yangtze River and runoff inflow from the basin were mainly responsible for the severe floods in 1990s. Also, the smallest storage capacity of Poyang Lake in 1990s due to the intensive human activities such as the great floodplain occupancy and levee construction further increased the severity of floods. While the rare floods in 2000s can be attributed to, on the one hand, the decrease in rainfall over the middle reaches of Yangtze River which caused the low streamflows of Yangtze River and runoff inflow from the Poyang Lake basin. On the other hand, the 'return land to lake' policy, intensive sand mining in the lake and the flood control of Three Gorges Dam also played an important role in mitigation of flood frequency and severity. [ABSTRACT FROM AUTHOR]

Recent climate changes have observable impacts on hydrologic processes and will further affect hydrologic systems in the future. The temperature and precipitation modeled with eight global circulation models (GCMs) (selected from 22 GCMs published in the Fourth Assessment of the Intergovernmental Panel on Climate Change) under three typical emission scenarios entitled A1B, A2, and B1 were evaluated in this study for future projections in the Yangtze River Basin, China. The artificial neural network model was used to assess the evolutional trend of hydrologic processes (e.g., streamflow) and the possibility of extreme floods in the Yangtze River Basin by using data generated by selected GCMs under future climate changes. The results indicate that the future annual streamflow tends to decrease in the Yangtze River Basin. The future average annual flow is reduced by compared with that of the historic record (1951-2005) observed at Yichang Hydrologic Station of the Middle Yangtze River, and the percentage of dry years increases by 46.8%. However, at Datong Hydrologic Station of the Lower Yangtze River, the average annual flow is reduced by compared to the historic record and the percentage of normal year increases up to 75.5%. Extreme floods are divided into three categories of catastrophic, great, and large floods. The results show that large floods are most likely to occur in the future, whereas the likelihood of extreme floods is the minimum under the B1 scenario. In the three decades of the 2020s, 2050s, and 2080s, the likelihood of extreme floods at Yichang and Datong Hydrologic Stations tends to increase; the likelihood of extreme floods at Yichang Hydrologic Station is much greater than that of the Datong Hydrologic Station. Variability in the quantity of water in these areas will pose a greater challenge to the integrated deployment and management of water resources in the Yangtze River Basin. [ABSTRACT FROM AUTHOR]

The quantitative attribution of changes in streamflow to climate change (CC) and land cover change (LCC) for the Yangtze River Source Region (YRSR), China, was assessed. We used a combination of the SWAT model along with the statistical technique one factor at a time (OFAT) and innovative trend analysis (ITA) to achieve the study objectives. The climate and hydrology data from 1961 to 2016 and land-cover maps of 5 years' difference from 1985 to 2015 were used. The model was calibrated (1964–1989) using a land-cover map of 1985 and validated for 1990–2016. This validated model was further validated for all other land-cover maps used in this study. The SWAT model simulation showed that streamflow had been significantly influenced by CC compared to LCC using land-cover maps of 1985–1990, 1990–1995. However, the SWAT model simulations did not result in further changes in streamflow for land cover maps of 2000–2005, 2005–2010, and 2010–2015 because there have not been any significant changes in land cover after 2000 while the main contributing factor was climate change. The SWAT model simulations showed that the main driver of changes in streamflow in the Yangtze River Source Region is climate change. This study shows that the individual impacts are more critical than combined impacts for designing hydraulic structures, water resources planning and management, and decision-making policies at the regional/basin scale. [ABSTRACT FROM AUTHOR]

While it is generally difficult to separate the impact of extreme climate events on river catchment conditions from that of human activities, there are unique data available to document this for the catchment area of the Yangtze in the years that the Three Gorges Dam (TGD) started to have an impact. During the second impoundment phase in 2006, the suspended sediment discharge (SSD) and water stored behind the TGD was and , respectively, which is only 18% of the total SSD reduction and about 1% of the water discharge () in 2005 at Datong. The total SSD and water discharge into the Yangtze Estuary in 2006 was 60 and 24% less than those in 2005, respectively. It can be quantified that the contribution of the extreme climate (drought) on discharge and SSD reduction was 95 and 82% of the total in 2006, respectively. In addition, it was found that the periods of high salinity (>250 and 400 mg/L) at Haimen that happened during the second impoundment phase accounted for 25 and 23% of the total occurrences in 2006, respectively. This analysis shows that the impact of extreme climate conditions can overrule the human interference, even for the largest dam, the TGD. [ABSTRACT FROM AUTHOR]

The article presents abstracts of several studies on environmental geochemistry. Some of the abstracts presented include "Biogeochemical Cycling of Nutrients in Karstic Catchments, Southwestern China: Linkages to Changes of Eco-Environments," by Congqiang Liu and "Emerging Organic Contamination in China," by Guibin Jiang and colleagues.

Although satellite radar altimetry was developed and optimized for open oceans, it has been used to monitor variations in the level of inland water-bodies such as lakes and rivers. Here, for the first time, we have further used the altimetry-derived variation of water level for estimating the fluctuation of water storage as an addition to the present in situ water storage estimation systems to be used in remote areas and in emergency situation such as in the events flooding monitoring and for studying the effect of climate change. Lake Dongting, the second largest lake in China, influenced frequently by flooding, was, therefore, chosen to demonstrate the potential of the technique. By using the concept of an “assumed reference point”, we converted Topex/Poseidon satellite altimetry data on water level variations in Lake Dongting to “water level” data. The “water level” time-series data and in situ water storage were used to establish a rating curve. From the rating curve, we converted data on “water level” derived from seven years (1993–1999) of Topex/Poseidon data to actual water storage in Lake Dongting. The result reveals that the seasonal and annual fluctuations of water storage occurred during the 1990s with a more frequent flooding at the late 1990s' especially the flooding in whole catchment level in 1998 and 1999. The study supports the usefulness of satellite altimetry for dense and continuous monitoring of the temporal variations in water dynamic in moderate to large lakes. [ABSTRACT FROM AUTHOR]

AMS14C dating and grain-size analysis for Core DD2, located at the north of the Yangtze River-derived mud off the Zhejiang-Fujian coasts in the inner shelf of the East China Sea, provide us a high-resolution grain-size distribution curve varying with depth and time. Data in the upper mud layer of Core DD2 indicate that there are at least 9 abrupt grain-size increasing in recent 2000 years, with each corresponding very well with the low-temperature events in Chinese history, which might result from the periodical strengthening of the East Asian Winter Monsoon (EAWM), including the first-revealed maximum temperature lowering event at around 990 a BP. At the same time, the finer grain size section in Core DD2 agrees well with the Sui-Tang Warming Period (600–1000 a AD) defined previously by Zhu Kezhen, during which the climate had a warm, cold and warm fluctuation, with a dominated cooling period of 750–850 a AD. The Little Ice Age (LIA) can also be identified in the core. It starts around 1450 a AD and was followed by a subsequent cooling events at 1510, 1670 and 1840 a AD. Timing of these cold events revealed here still needs to be further verified owing to some current uncertainty of dating we used in this study. [ABSTRACT FROM AUTHOR]

The upstream Yangtze River is located in the southwest of central China, where it flows through several ecosystems and densely populated regions that constitute a unique complex coupled system. To determine how the characteristics of supply and demand in a water-coupled system will vary under the influence of climate change and human activity in this area in the next 85 years, the upper Yangtze basin was considered as the study area and was divided into seven sub-basins according to seven main control sections: Shigu, Panzhihua, Xiluodu, Xiangjiaba, Zhutuo, Cuntan, and Yichang; a method for water supply and demand research considering climate change was proposed. Based on simulated runoff in the study area under changing environmental conditions, this study analyzed the available water supply and constructed a long-term water demand forecasting model using the classified water use index method under macro regulation in the study area from 2016 to 2100. The results show that the total water demand in the upstream Yangtze River appears to first increase and then decrease in 2016–2100 and will reach its peak around 2028. The ecological pressure in the upstream Yangtze River increases gradually from upstream to downstream but will not reach the surface water utilization stress threshold (hereinafter referred to as stress threshold) for the next 85 years. The contradiction between monthly supply and demand is more prominent under ecological restrictions. Under the RCP4.5 scenario, water demand exceeds the stress threshold in each sub-basin across several months (mainly March, April, and May), and the water demand nearly reaches the damage threshold in May as the basin extends below the Zhutuo section. [ABSTRACT FROM AUTHOR]

Characterized by increasing surface air temperature, global warming has altered the hydrological cycle at global and regional scales. In order to adapt water resources management under the context of global warming, attribution analysis on regional differentiation of water resources in the Yangtze River basin (YRB) was conducted in this study. Meteoro-hydrological variations across the basin were examined for the period 1960–2013, and then a statistic-based method was applied in quantifying the contributions of climate variability and human activities on annual runoff variations in different tributary sub-basins in the YRB. Our observation indicates that both the annual increasing rate and the inter-annual fluctuations of temperature in China and in the YRB were higher than that of the global average since the turn of the century. Climate change analysis indicates that the YRB experienced a hot-wet period during 1994–2002 and a hot-dry period during 2003–2013, since the step change of temperature in 1993. Contributions of climate change and human activities on runoff variations varied spatially in the basin. With reference to the baseline period of 1960–1993, the contribution of climate change played a dominant role in most regions of the basin, especially in those upstream sub-basins. The effect of human activities in the basin was quite complicated, not only its regional differentiation, but also its contribution were opposite during the hot-wet period and the hot-dry period in some sub-basins. The result of this study is helpful in understanding the impacts of climate change and human activities on water resources variation in both temporal and spatial scales. [ABSTRACT FROM AUTHOR]

The headwaters of the Yangtze River are located on the Qinghai Tibetan Plateau, which is affected by climate change. Here, treamflow trends for Tuotuohe and Zhimenda sub-basins and relations to temperature and precipitation trends during 1961–2015 were investigated. The modified Mann–Kendall trend test, Pettitt test, wavelet analysis, and multivariate correlation analysis was deployed for this purpose. The temperature and precipitation significantly increased for each sub-basin, and the temperature increase was more significant in Tuotuohe sub-basin as compared to the Zhimenda sub-basin. A statistically significant periodicity of 2–4 years was observed for both sub-basins in different time spans. Higher flow periodicities for Tuotuohe and Zhimenda sub-basin were found after 1991 and 2004, respectively, which indicates that these are the change years of trends in streamflows. The influence of temperature on streamflow is more substantial in Tuotuohe sub-basin, which will ultimately impact the melting of glaciers and snowmelt runoff in this sub-basin. Precipitation plays a more critical role in the Zhimenda streamflow. Precipitation and temperature changes in the headwaters of the Yangtze River will change the streamflow variability, which will ultimately impact the hydropower supply and water resources of the Yangtze Basin. This study contributes to the understanding of the dynamics of the hydrological cycle and may lead to better hydrologic system modeling for downstream water resource developments. [ABSTRACT FROM AUTHOR]

The change in river flows at the basin scale reflects the combined influences of changes in various environmental factors associated with climatic and underlying surface properties. Distinguishing the relative contribution of each of these factors to runoff change is critical for sustainable water resource management, but it is also challenging. The headstream region of the Yangtze River, known as "China's Water Tower", has undergone a significant runoff change over the past decades. However, the relative contribution of environmental factors to runoff change is still unclear. Here, we designed a series of detrending experiments based on a grid-based hydrological model to quantify the combined influences of multiple environmental factors on runoff change and the relative contribution of an individual factor to runoff change. The results indicate that changes in climate and vegetation significantly increased water yield in the study basin over the past three decades, and the increase in water yield primarily came from the contribution from the upstream of the basin. On the basin scale, the change in precipitation dominated the runoff change that contributed up to 113.2% of the runoff change, followed by the wind speed change with a contribution rate of −15.1%. Other factors, including changes in temperature, relative humidity, sunshine duration (as a surrogate for net radiation), and albedo (as a surrogate for vegetation) had limited effects on runoff change, and the contribution rate of these factors to runoff change ranged from −5% to 5%. On spatial patterns, the influences of changes in some environmental factors on runoff changes were affected by elevation, particularly for temperature. The rising temperature had mixed effects on runoff change, which generally increased water yield at high altitudes of the basin but decreased water yield at low altitudes of the basin. [ABSTRACT FROM AUTHOR]

The water temperature of rivers is of considerable significance to freshwater ecosystems and human water use. In contrast to traditional regression models or other deterministic statistical models, we present a probabilistic approach to examine the joint dependence structures of water‐air temperature and water temperature‐discharge in the Yangtze River. Such dependence structures were built based on bivariate probabilistic models with well‐fitted marginal distributions of each variable. To investigate the stability of the dependence structures and the effects of the Three Gorges Dam (TGD), three stations (i.e., Cuntan, Yichang, and Datong) located in different sections of the river were involved in comparison between two periods, that is, pre‐TGD (1975–1987) and post‐TGD (2003–2014) periods (the dam began operating in 2003). Our results indicate that at the three stations the joint occurrence probabilities of the air‐water temperature events (e.g., the compound extreme events) tend to be lower for the second period. The dependence structures of water temperature and river discharge were stable between the two periods at the upstream station. For the downstream station relatively close to the TGD (Yichang station), a clear disturbance was observed in the dependence structures of water temperature‐discharge. In addition, relying on the established bivariate and trivariate dependence models, we further assessed the risk of different water temperature events under individual and coupled extreme conditions of air temperature and discharge. The trivariate model also revealed substantial changes in the probabilistic difference between the pre‐TGD and post‐TGD periods at Yichang station, indicating the impact from the TGD. Key Points: A probabilistic method to examine the dependence of water/air temperature and discharge is describedThe dependence of water/air temperature and discharge at Yichang site are strongly affected by the damThe method also enables the risk estimation for different water temperature events [ABSTRACT FROM AUTHOR]