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Wenchao Sun
Beijing Key Laboratory of Urban Hydrological Cycle and Sponge City Technology, College of Water Sciences, Beijing Normal University, Xinjiekouwai Street 19, Beijing 100875, China

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Journal article
Published: 23 March 2021 in Remote Sensing
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Hydrological connectivity is an important characteristic of wetlands that maintains the stability and functions of an ecosystem. This study investigates the temporal variations of hydrological connectivity and their driving mechanism in Baiyangdian Lake, a large shallow wetland in North China, using a time series of open water surface area data derived from 36 Landsat 8 multispectral images from 2013–2019 and in situ measured water level data. Water area classification was implemented using the Google Earth Engine. Six commonly used indexes for extracting water surface data from satellite images were compared and the best performing index was selected for the water classification. A composite hydrological connectivity index computed from open water area data derived from Landsat 8 images was developed based on several landscape pattern indices and applied to Baiyangdian Lake. The results show that, reflectance in the near-infrared band is the most accurate index for water classification with >98% overall accuracy because of its sensitivity to different land cover types. The slopes of the best-fit linear relationships between the computed hydrological connectivity and observed water level show high variability between years. In most years, hydrological connectivity generally increases when water levels increase, with an average R2 of 0.88. The spatial distribution of emergent plants also varies year to year owing to interannual variations of the climate and hydrological regime. This presents a possible explanation for the variations in the annual relationship between hydrological connectivity and water level. For a given water level, the hydrological connectivity is generally higher in spring than summer and autumn. This can be explained by the fact that the drag force exerted by emergent plants, which reduces water flow, is smaller than that for summer and autumn owing to seasonal variations in the phenological characteristics of emergent plants. Our study reveals that both interannual and seasonal variations in the hydrological connectivity of Baiyangdian Lake are related to the growth of emergent plants, which occupy a large portion of the lake area. Proper vegetation management may therefore improve hydrological connectivity in this wetland.

ACS Style

Ziqi Li; Wenchao Sun; Haiyang Chen; Baolin Xue; Jingshan Yu; Zaifeng Tian. Interannual and Seasonal Variations of Hydrological Connectivity in a Large Shallow Wetland of North China Estimated from Landsat 8 Images. Remote Sensing 2021, 13, 1214 .

AMA Style

Ziqi Li, Wenchao Sun, Haiyang Chen, Baolin Xue, Jingshan Yu, Zaifeng Tian. Interannual and Seasonal Variations of Hydrological Connectivity in a Large Shallow Wetland of North China Estimated from Landsat 8 Images. Remote Sensing. 2021; 13 (6):1214.

Chicago/Turabian Style

Ziqi Li; Wenchao Sun; Haiyang Chen; Baolin Xue; Jingshan Yu; Zaifeng Tian. 2021. "Interannual and Seasonal Variations of Hydrological Connectivity in a Large Shallow Wetland of North China Estimated from Landsat 8 Images." Remote Sensing 13, no. 6: 1214.

Journal article
Published: 29 September 2020 in Journal of Hydrology
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Drought is a major climate disturbance that can lower vegetation productivity and induce widespread vegetation die-off, which in turn can have a profound effect on the water cycle. Therefore, quantification of vegetation-specific responses to drought is essential to predict the impacts of climate change on ecosystem services. We used two previously-suggested quantitative metrics – dynamic deviation (d) and elasticity (e) based on the Budyko framework –to evaluate site- and watershed-level hydrological resilience of different plant functional types (PFTs) to drought. By using data from 41 FLUXNET sites and 2275 watersheds, we found a global convergence in hydrological resilience to drought across a variety of PFTs. Hydrological resilience of vegetation was related to drought intensity and water use efficiency. A greater hydrological resilience was found in PTFs in drier areas than in wetter areas, while this greater hydrological resilience was related to the coefficient of variation in precipitation. We also found that PFTs with a larger water use efficiency had higher hydrological resilience, particularly in drier regions, indicating adaptation strategies to changes in local climate conditions. Our findings can shed light on how ecosystems and watersheds dominated by different PFTs will respond to future climatic change and inform water resources management.

ACS Style

Baolin Xue; Guoqiang Wang; Jingfeng Xiao; David Helman; Wenchao Sun; Jianhua Wang; Tingxi Liu. Global convergence but regional disparity in the hydrological resilience of ecosystems and watersheds to drought. Journal of Hydrology 2020, 591, 125589 .

AMA Style

Baolin Xue, Guoqiang Wang, Jingfeng Xiao, David Helman, Wenchao Sun, Jianhua Wang, Tingxi Liu. Global convergence but regional disparity in the hydrological resilience of ecosystems and watersheds to drought. Journal of Hydrology. 2020; 591 ():125589.

Chicago/Turabian Style

Baolin Xue; Guoqiang Wang; Jingfeng Xiao; David Helman; Wenchao Sun; Jianhua Wang; Tingxi Liu. 2020. "Global convergence but regional disparity in the hydrological resilience of ecosystems and watersheds to drought." Journal of Hydrology 591, no. : 125589.

Journal article
Published: 22 September 2020 in Ecological Engineering
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While evapotranspiration (ET) is an important component of the global water cycle, its temporal variations (ΔET) and underlying mechanisms are controversial. Based on the newest FLUXNET dataset and six ET products, we investigate ΔET for different ecosystem types during the recent two decades (1995–2014). We found an ET hiatus (decreasing in ET) at most sites (46 of 67) based on both in-situ observations and the ET products. The environmental drivers, surface conductance (Gs) and water use efficiency (WUE) are found to be responsible for ΔET. Changes in structural (by leaf area index, or LAI) and physiological (by Gs and WUE) variables contributed nearly equally to ΔET. Although Gs may impose a larger positive effect on ET than LAI, its effect may substantially offset the negative effect via WUE. Our study provides robust observational evidence that global ET stayed roughly unchanged in the past two decades. The results also highlight the importance of incorporating both vegetation structural and physiological effects in the projections of ΔET under a changing climate.

ACS Style

Baolin Xue; Guoqiang Wang; Jingfeng Xiao; Qian Tan; Sangam Shrestha; Wenchao Sun; Tingxi Liu. Global evapotranspiration hiatus explained by vegetation structural and physiological controls. Ecological Engineering 2020, 158, 106046 .

AMA Style

Baolin Xue, Guoqiang Wang, Jingfeng Xiao, Qian Tan, Sangam Shrestha, Wenchao Sun, Tingxi Liu. Global evapotranspiration hiatus explained by vegetation structural and physiological controls. Ecological Engineering. 2020; 158 ():106046.

Chicago/Turabian Style

Baolin Xue; Guoqiang Wang; Jingfeng Xiao; Qian Tan; Sangam Shrestha; Wenchao Sun; Tingxi Liu. 2020. "Global evapotranspiration hiatus explained by vegetation structural and physiological controls." Ecological Engineering 158, no. : 106046.

Journal article
Published: 03 March 2020 in Water
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Baiyangdian Lake, the largest freshwater body in Northern China, is facing water shortage and eutrophication problems that threaten the lake’s ecosystem. Environmental water releases from upstream reservoirs to the lake are important measures to provide the freshwater resources demanded by the lake ecosystem. However, knowledge is limited regarding the influences of such water allocations on the water quality of the upstream rivers that receive the reservoir water and transport it into Baiyangdian Lake. To improve our understanding of possible influences of environmental water releases from upstream reservoirs, the spatial variation of water quality in rivers upstream of the lake during environmental water release periods from reservoirs was explored in this study. Water samples were collected along the two routes of water allocation: the WangKuai reservoir route (WKR) and the XiDaYang reservoir route (XDYR) and water quality parameters related to organic pollutants, nitrogen and phosphorus were analyzed. In the WKR, the pollutant concentrations generally increased from upstream to downstream. Chemical oxygen demand, total nitrogen, and total phosphorous at the sampling site closest to Baiyangdian Lake could not meet the water quality target of the water function zone. For the XDYR, pollutant concentrations peaked downstream of the major urban region of Baoding city and then decreased or remained at a similar level further downstream and only the total nitrogen concentration was worse than the target. The dissimilarities in spatial variation patterns of water quality may be caused by the different spatial distribution of wastewater treatment plants in the two routes.

ACS Style

Ling Zhou; Wenchao Sun; Quan Han; Haiyang Chen; He Chen; Yongliang Jin; Runze Tong; Zaifeng Tian. Assessment of Spatial Variation in River Water Quality of the Baiyangdian Basin (China) during Environmental Water Release Period of Upstream Reservoirs. Water 2020, 12, 688 .

AMA Style

Ling Zhou, Wenchao Sun, Quan Han, Haiyang Chen, He Chen, Yongliang Jin, Runze Tong, Zaifeng Tian. Assessment of Spatial Variation in River Water Quality of the Baiyangdian Basin (China) during Environmental Water Release Period of Upstream Reservoirs. Water. 2020; 12 (3):688.

Chicago/Turabian Style

Ling Zhou; Wenchao Sun; Quan Han; Haiyang Chen; He Chen; Yongliang Jin; Runze Tong; Zaifeng Tian. 2020. "Assessment of Spatial Variation in River Water Quality of the Baiyangdian Basin (China) during Environmental Water Release Period of Upstream Reservoirs." Water 12, no. 3: 688.

Journal article
Published: 22 February 2020 in Journal of Hydrology
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Hydrologic pulse represent one of the dominant factors controlling the distribution of aquatic organisms. Changes in hydrologic pulses may change the surroundings of the organism and then affect their distribution and community structure. Here, based on the data from a rainy season and a dry season, the water quality, heavy metal in the sediment and macrozoobenthos community structure in two shallow lakes, Nansihu Lake (NSH) and Dongpinghu Lake (DPH, were analyzed. The results showed that the water diversion pulse participated in the influence of runoff pulse on NSH and DPH. The macrozoobenthos community in NSH and DPH were similar after the hydrologic pulse changed, this might be due to these two lakes were connected by the South-to-North Water Transfer Project (SNWTP). Along the direction of water transfer, the macrozoobenthos communities were gradually dominated by small-size species with as water quality decreased. Compared with community structure before the SNWTP, the macrozoobenthos changed from dominant aquatic insect to dominant Mollusca in NSH, and changed from dominant Mollusca and Oligochaeta to dominant Mollusca in DPH. The water diversion pulse, in which the direction of water transfer was opposite to that of natural water flow, affected the distribution of nitrogen and phosphorous in water and heavy metals in sediment. In addition, the introduction of exogenous water caused by the SNWTP changed water quality and heavy metals content in the sediment and water depth in NSH and DPH. These changes together affected the community structure and distribution of macrozoobenthos. These findings enable a better understanding of the ecological impact of intense hydrologic pulse changes caused by water transfer projects.

ACS Style

Qing Li; Guoqiang Wang; Hongqi Wang; Sangam Shrestha; Baolin Xue; Wenchao Sun; Jingshan Yu. Macrozoobenthos variations in shallow connected lakes under the influence of intense hydrologic pulse changes. Journal of Hydrology 2020, 584, 124755 .

AMA Style

Qing Li, Guoqiang Wang, Hongqi Wang, Sangam Shrestha, Baolin Xue, Wenchao Sun, Jingshan Yu. Macrozoobenthos variations in shallow connected lakes under the influence of intense hydrologic pulse changes. Journal of Hydrology. 2020; 584 ():124755.

Chicago/Turabian Style

Qing Li; Guoqiang Wang; Hongqi Wang; Sangam Shrestha; Baolin Xue; Wenchao Sun; Jingshan Yu. 2020. "Macrozoobenthos variations in shallow connected lakes under the influence of intense hydrologic pulse changes." Journal of Hydrology 584, no. : 124755.

Journal article
Published: 14 February 2020 in Sustainability
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Extreme weather events can cause a lot of damage in highly populated regions, such as in the Beijing–Tianjin–Hebei Region (BTHR) in northern China. To understand where and how extreme precipitation and temperature events are changing within the BTHR, data for 1959–2018 from 25 mereological stations were used to detect trends in the intensity, frequency, and duration of these events. The results showed that intensity, accumulated amount, the duration of extreme precipitation events, and the annual number of days with precipitation greater than 50 mm decreased on a regional scale over this 60-year period. Changes in extreme precipitation events at most stations were not statistically significant, although a few stations had a significant downward trend. The combined effects of the East Asian summer monsoon and rapid urbanization are possible reasons for these trends. Both the annual maximum and minimum temperature increased on a regional and local scale. The frequency of extreme hot and cold weather also, respectively, increased and decreased, with consistent patterns on a regional and local scale. However, the spatial changes of these trends were different, reflecting the effects of irrigation and urbanization on the regional surface energy balance. These findings are valuable to decisionmakers involved in disaster prevention in the BTHR and in other highly populated regions worldwide.

ACS Style

Runze Tong; Wenchao Sun; Quan Han; Jingshan Yu; Zaifeng Tian. Spatial and Temporal Variations in Extreme Precipitation and Temperature Events in the Beijing–Tianjin–Hebei Region of China over the Past Six Decades. Sustainability 2020, 12, 1415 .

AMA Style

Runze Tong, Wenchao Sun, Quan Han, Jingshan Yu, Zaifeng Tian. Spatial and Temporal Variations in Extreme Precipitation and Temperature Events in the Beijing–Tianjin–Hebei Region of China over the Past Six Decades. Sustainability. 2020; 12 (4):1415.

Chicago/Turabian Style

Runze Tong; Wenchao Sun; Quan Han; Jingshan Yu; Zaifeng Tian. 2020. "Spatial and Temporal Variations in Extreme Precipitation and Temperature Events in the Beijing–Tianjin–Hebei Region of China over the Past Six Decades." Sustainability 12, no. 4: 1415.

Journal article
Published: 24 October 2019 in Science of The Total Environment
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Baiyangdian Lake, the largest shallow lake in the North China Plain, is essential for maintaining ecosystem functioning in this highly populated region. To explore the influences of human activities on the lake’s water quality, an improved Water Quality Index (WQI) method and multivariate statistical techniques were adopted to assess the temporal and spatial variations of the lake’s water quality and explore the dominant factors of these variations. Datasets for 11 water quality parameters from six monitoring stations were used to evaluate the period spanning from 2006 to 2016. Assessment of the annual WQI showed that the water quality of the lake has generally improved over the past decade. Cluster analysis divided 12 months into the dry and wet periods and the six monitoring stations into those located in the western and eastern parts of the lake. Discriminant analysis demonstrated that with only two parameters (water temperature and fluoride) and six parameters (dissolved oxygen, ammonia nitrogen, total nitrogen, total phosphorus, anionic surfactant, and fecal coliform), 96.0% and 93.8% of the water quality data can be classified into the correct spatial and temporal clusters, respectively. For the principal component analysis and factor analysis, the varifactors detected for the two temporal clusters were similar, and varifactors related to pollution explained more variance in the water quality variation than the ones representing natural factors. For the two spatial clusters, the varifactors were different, indicating they are influenced by different types of anthropogenic activities. Correlation analysis between lake water level and water quality indicated that environmental water allocation to the lake generally improve water quality. These findings provide a more thorough understanding of driving mechanism of water quality and may be helpful for making environmental management decisions in Baiyangdian Lake and other large, shallow lakes in highly populated dryland regions.

ACS Style

Quan Han; Runze Tong; Wenchao Sun; Yue Zhao; Jingshan Yu; Guoqiang Wang; Sangam Shrestha; Yongliang Jin. Anthropogenic influences on the water quality of the Baiyangdian Lake in North China over the last decade. Science of The Total Environment 2019, 701, 134929 .

AMA Style

Quan Han, Runze Tong, Wenchao Sun, Yue Zhao, Jingshan Yu, Guoqiang Wang, Sangam Shrestha, Yongliang Jin. Anthropogenic influences on the water quality of the Baiyangdian Lake in North China over the last decade. Science of The Total Environment. 2019; 701 ():134929.

Chicago/Turabian Style

Quan Han; Runze Tong; Wenchao Sun; Yue Zhao; Jingshan Yu; Guoqiang Wang; Sangam Shrestha; Yongliang Jin. 2019. "Anthropogenic influences on the water quality of the Baiyangdian Lake in North China over the last decade." Science of The Total Environment 701, no. : 134929.

Journal article
Published: 11 September 2019 in Science of The Total Environment
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Ecological water use efficiency (WUE) is a crucial indicator of hydrological and vegetation carbon cycle coupling and can drastically affect water and energy exchanges. However, little is known about the sensitivity of WUE to water–energy exchange in semiarid regions. Moreover, few studies have considered the link between WUE and water–energy exchange models, i.e., the Budyko-type framework. Here, we investigated the relationships between WUE and a Budyko-type model in a semiarid basin. Seven primary indicators were selected to represent the water, energy, and vegetation variations in the ecosystem: gross primary productivity (GPP), air temperature (T), potential evapotranspiration (PET), evapotranspiration (ET), precipitation (P), soil water content (SWC), and snow water equivalent (SWE). Three similar ecological WUEs were defined as GPP/ET, GPP/P, and GPP/SWC to analyze the factors of the water–energy exchange model (i.e., ET/P, PET/P, SWC/P, and SWE/P). Based on the results, four linear Budyko-type models were proposed for the basin (GPP/P, ET/P, SWC/P, and SWE/P as a function of PET/P). The results suggested that both SWC and P influenced the trend of GPP variation, whereas P influenced the lower limit of GPP or GPP/P within the Budyko model for grassland areas. The results indicated that the rate of increase of SWC was lower than that of P in forest areas because of differences in canopy structure. The results also revealed a nonlinear (s-type) relationship between the WUEs and the underlying surface parameter m within the Budyko framework, suggesting that unit plant productivity consumes less water when the water–energy supply condition is invariant, if the variation of the underlying surface characteristics promotes the increase of m. Our research provides new insight regarding quantification of the sensitivity of WUE to the water–energy balance in a semiarid region.

ACS Style

Qingqing Fang; Guoqiang Wang; Tingxi Liu; Baolin Xue; Wenchao Sun; Sangam Shrestha. Unraveling the sensitivity and nonlinear response of water use efficiency to the water–energy balance and underlying surface condition in a semiarid basin. Science of The Total Environment 2019, 699, 134405 .

AMA Style

Qingqing Fang, Guoqiang Wang, Tingxi Liu, Baolin Xue, Wenchao Sun, Sangam Shrestha. Unraveling the sensitivity and nonlinear response of water use efficiency to the water–energy balance and underlying surface condition in a semiarid basin. Science of The Total Environment. 2019; 699 ():134405.

Chicago/Turabian Style

Qingqing Fang; Guoqiang Wang; Tingxi Liu; Baolin Xue; Wenchao Sun; Sangam Shrestha. 2019. "Unraveling the sensitivity and nonlinear response of water use efficiency to the water–energy balance and underlying surface condition in a semiarid basin." Science of The Total Environment 699, no. : 134405.

Journal article
Published: 03 September 2019 in Science of The Total Environment
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This paper addresses the problem of missing latent time series information caused by the differences in the analysis of time series data and non-time series data. A time series trend structure model (TSTM) was established using the analysis of time series patterns and rules, the trends of patterns and rules, and trends in confidence and support. Shandong Province was selected as the study area. Rainfall and evaporation time series data from this area were input into the TSTM. The results show that: (1) the structure of multi-year precipitation and evaporation trends of the meteorological stations in the study area have continuously increasing or decreasing characteristics. The TSTM can excavate the different trend structure characteristics of different meteorological elements and enables diversity in time series data analysis; (2) the evaporation trend structure tends to change synchronously with increases and decreases in precipitation and evaporation. The synchronous change frequency is essentially the same as that of the rainfall trend structure. This indicates that the TSTM has spatial and temporal characteristics for time series data analysis; and (3) from the maximal non-descending and non-ascending subsequence in the TSTM, it can be concluded that there exists continuity in the years when the trend structure of precipitation and evaporation increases and decreases synchronously. In addition, the degree of similarity in the model is well reflected in the spatial distribution characteristics of time series data, and the model provides clustering characteristics for time series data analysis. The TSTM proposed in this paper can effectively obtain the potential hydrological information contained in time series data, and provides a scientific and reliable basis for rules for the spatial optimization of watershed data and for the calibration of hydrological models.

ACS Style

Jiping Yao; Puze Wang; Guoqiang Wang; Sangam Shrestha; Baolin Xue; Wenchao Sun. Establishing a time series trend structure model to mine potential hydrological information from hydrometeorological time series data. Science of The Total Environment 2019, 698, 134227 .

AMA Style

Jiping Yao, Puze Wang, Guoqiang Wang, Sangam Shrestha, Baolin Xue, Wenchao Sun. Establishing a time series trend structure model to mine potential hydrological information from hydrometeorological time series data. Science of The Total Environment. 2019; 698 ():134227.

Chicago/Turabian Style

Jiping Yao; Puze Wang; Guoqiang Wang; Sangam Shrestha; Baolin Xue; Wenchao Sun. 2019. "Establishing a time series trend structure model to mine potential hydrological information from hydrometeorological time series data." Science of The Total Environment 698, no. : 134227.

Journal article
Published: 30 August 2019 in Science of The Total Environment
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Sustainable management strategies for water resources rely on accurate knowledge about the dynamics of hydrological processes, especially in drylands, where freshwater is the limiting factor for the development of human society and ecosystems. The populated Loess Plateau (LP) in North China is a typical semi-arid region where competition for water between people and nature is worth noting because of afforestation promoted by the Grain to Green Program. In this study, changes in key components of terrestrial water storage (TWS) in the LP were explored using a multi-satellite approach, including Gravity Recovery and Climate Experiment (GRACE) observations and Earth observations of precipitation, evapotranspiration and soil moisture. By integrating data on human water use from different sources with satellite observations, we were able to examine the mechanisms driving these changes. The results demonstrated that, according to an evaluation based on reproducing TWS computed from the regional water balance in the LP, the mascon solution of the Center for Space Research (CSR) at University of Texas at Austin performed best out of the commonly used GRACE products. Regional TWS derived from the CSR mascon solution in the LP decreased significantly for the period 2003-2015. Significant decreases were also detected for regional ground water storage (GWS) estimated by decomposing the GRACE TWS using multi-sources remote sensing data. GWS made the greatest contribution to the changes in TWS. Increased plant transpiration was one reason for the decreasing trend of GWS. Because changes in precipitation, soil moisture and water consumed by irrigation were minor at regional scales, we concluded that the increase of transpiration is driven by deep-rooted trees planted, which use the part of precipitation that previously recharged groundwater. The findings from this study are valuable for water resource management and ecological restoration in semi-arid regions with high populations.

ACS Style

Wenchao Sun; Yongliang Jin; Jingshan Yu; Guoqiang Wang; Baolin Xue; Yue Zhao; Yongshuo Fu; Sangam Shrestha. Integrating satellite observations and human water use data to estimate changes in key components of terrestrial water storage in a semi-arid region of North China. Science of The Total Environment 2019, 698, 134171 .

AMA Style

Wenchao Sun, Yongliang Jin, Jingshan Yu, Guoqiang Wang, Baolin Xue, Yue Zhao, Yongshuo Fu, Sangam Shrestha. Integrating satellite observations and human water use data to estimate changes in key components of terrestrial water storage in a semi-arid region of North China. Science of The Total Environment. 2019; 698 ():134171.

Chicago/Turabian Style

Wenchao Sun; Yongliang Jin; Jingshan Yu; Guoqiang Wang; Baolin Xue; Yue Zhao; Yongshuo Fu; Sangam Shrestha. 2019. "Integrating satellite observations and human water use data to estimate changes in key components of terrestrial water storage in a semi-arid region of North China." Science of The Total Environment 698, no. : 134171.

Journal article
Published: 05 June 2019 in Water
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Distributed hydrological models play a vital role in water resources management. With the rapid development of distributed hydrological models, research into model uncertainty has become a very important field. When studying traditional hydrological model uncertainty, it is very common to use multisite observation data to evaluate the performance of the model in the same watershed, but there are few studies on uncertainty in watersheds with different characteristics. This study is based on the Soil and Water Assessment Tool (SWAT) model, and uses two common methods: Sequential Uncertainty Fitting Version 2 (SUFI-2) and Generalized Likelihood Uncertainty Estimation (GLUE) for uncertainty analysis. We compared these methods in terms of parameter uncertainty, model prediction uncertainty, and simulation effects. The Xiaoqing River basin and the Xinxue River basin, which have different characteristics, including watershed geography and scale, were used for the study areas. The results show that the GLUE method had better applicability in the Xiaoqing River basin, and that the SUFI-2 method provided more reasonable and accurate analysis results in the Xinxue River basin; thus, the applicability was higher. The uncertainty analysis method is affected to some extent by the characteristics of the watershed.

ACS Style

Lufang Zhang; Baolin Xue; Yuhui Yan; Guoqiang Wang; Wenchao Sun; Zhanjie Li; Jingshan Yu; Gang Xie; Huijian Shi. Model Uncertainty Analysis Methods for Semi-Arid Watersheds with Different Characteristics: A Comparative SWAT Case Study. Water 2019, 11, 1177 .

AMA Style

Lufang Zhang, Baolin Xue, Yuhui Yan, Guoqiang Wang, Wenchao Sun, Zhanjie Li, Jingshan Yu, Gang Xie, Huijian Shi. Model Uncertainty Analysis Methods for Semi-Arid Watersheds with Different Characteristics: A Comparative SWAT Case Study. Water. 2019; 11 (6):1177.

Chicago/Turabian Style

Lufang Zhang; Baolin Xue; Yuhui Yan; Guoqiang Wang; Wenchao Sun; Zhanjie Li; Jingshan Yu; Gang Xie; Huijian Shi. 2019. "Model Uncertainty Analysis Methods for Semi-Arid Watersheds with Different Characteristics: A Comparative SWAT Case Study." Water 11, no. 6: 1177.

Journal article
Published: 17 April 2019 in Journal of Hydrology
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Changes in vegetation growth may influence the availability of water resources. Located on the Tibetan Plateau, the Yarlung Zangbo River Basin (YZRB) is a major freshwater source for Tibet, China and downstream South Asian countries, with high spatial heterogeneity in altitude and climate from the upstream to downstream regions. In this study, we combined satellite-based gridded datasets of the normalized difference vegetation index (NDVI), topography, precipitation, and temperature to investigate how vegetation growth has changed in the YZRB over recent decades (1982–2010), and to determine their driving mechanisms. Although a statistically significant trend in growing season NDVI was not detected at the basin scale, at the pixel scale 16.8% and 5.3% of the area of the YZRB was found to exhibit increasing and decreasing trends, respectively. The greatest increases occurred in the Nyang subbasin. Variations of NDVI values along elevation, precipitation, and temperature gradients revealed the greatest variation over the middle ranges of the three variables. Partial correlation analyses indicate that in both arid and semi-arid regions of the YZRB precipitation is positively correlated with NDVI. The relationship between NDVI and temperature varies with aridity, reflecting different effects of snow-melting processes on vegetation growth. Temperature positively correlates with NDVI in the arid region. In addition, a negative correlation between NDVI and temperature is detected in the semi-arid region. This is the first comprehensive study to explore climate–vegetation–hydrology relationships in the YZRB at a spatial resolution finer than those derived from sparse in-situ meteorological stations or low resolution global climate datasets. Our results are valuable for understanding ecohydrological processes in both arid and semi-arid regions of this internationally important river basin.

ACS Style

Wenchao Sun; Yuanyuan Wang; Yongshuo H. Fu; Baolin Xue; Guoqiang Wang; Jingshan Yu; Depeng Zuo; Zongxue Xu. Spatial heterogeneity of changes in vegetation growth and their driving forces based on satellite observations of the Yarlung Zangbo River Basin in the Tibetan Plateau. Journal of Hydrology 2019, 574, 324 -332.

AMA Style

Wenchao Sun, Yuanyuan Wang, Yongshuo H. Fu, Baolin Xue, Guoqiang Wang, Jingshan Yu, Depeng Zuo, Zongxue Xu. Spatial heterogeneity of changes in vegetation growth and their driving forces based on satellite observations of the Yarlung Zangbo River Basin in the Tibetan Plateau. Journal of Hydrology. 2019; 574 ():324-332.

Chicago/Turabian Style

Wenchao Sun; Yuanyuan Wang; Yongshuo H. Fu; Baolin Xue; Guoqiang Wang; Jingshan Yu; Depeng Zuo; Zongxue Xu. 2019. "Spatial heterogeneity of changes in vegetation growth and their driving forces based on satellite observations of the Yarlung Zangbo River Basin in the Tibetan Plateau." Journal of Hydrology 574, no. : 324-332.

Journal article
Published: 27 March 2019 in Water Research
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A simple, transparent and reliable method for evaluating non-point source pollution (NPSP) risks to drinking water source areas lacking observational data is proposed herein. The NPSP risks are assessed by using nutrient budget models for total nitrogen and total phosphorus, making the best use of remote sensing and field survey data. We demonstrate its potential using a case study of the Chaihe Reservoir in northeastern China. Fertilizer inputs and crop-uptake outputs were estimated based on normalized difference vegetation index, which is derived from remote sensing as indicators of crop growth and production. The nutrient balances for this area showed surpluses of both N and P within the soil system. Estimated imbalances per unit area were consistent with statistical relationships derived from all Chinese counties, demonstrating that the proposed method is reliable. The surplus P amounts were higher than the standard threshold for NPSP risks, indicating the existence of a potential contamination risk of P to this drinking water source.

ACS Style

Guoqiang Wang; Jiawei Li; Wenchao Sun; Baolin Xue; Yinglan A; Tingxi Liu. Non-point source pollution risks in a drinking water protection zone based on remote sensing data embedded within a nutrient budget model. Water Research 2019, 157, 238 -246.

AMA Style

Guoqiang Wang, Jiawei Li, Wenchao Sun, Baolin Xue, Yinglan A, Tingxi Liu. Non-point source pollution risks in a drinking water protection zone based on remote sensing data embedded within a nutrient budget model. Water Research. 2019; 157 ():238-246.

Chicago/Turabian Style

Guoqiang Wang; Jiawei Li; Wenchao Sun; Baolin Xue; Yinglan A; Tingxi Liu. 2019. "Non-point source pollution risks in a drinking water protection zone based on remote sensing data embedded within a nutrient budget model." Water Research 157, no. : 238-246.

Journal article
Published: 02 May 2018 in Sustainability
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The Yarlung Zangbo River Basin (YZRB) is an important transboundary river basin in Tibet, China with south Asian countries. Changes in precipitation are important driving factors of river flow changes. Extreme Precipitation Events (EPE), in particular, have serious impacts on human life and sustainable development. The objective of this study is to explore the temporal changes and the spatial distribution of EPE over the YZRB in recent decades using a precipitation product with a 5 km spatial resolution and the Mann–Kendall nonparametric statistical test method. A more thorough understanding of the spatial heterogeneity in precipitation was expected from using this high resolution dataset. At both basin and pixel scale, both annual precipitation amounts and number of rain days had significant upward trends, indicating that the increase in the number of rain days is one possible cause of the annual precipitation amounts increases. The annual precipitation and number of rain days increased significantly in 50.8% and 75.8% of the basin area, respectively. The areas showing upward trends for the two indexes mostly overlapped, supporting the hypothesis that the increasing number of rain days is one possible cause of the increases in annual precipitation in these areas. General precipitation intensity and EPE intensity increased in the Lhasa regions and in the southern part of the lower-reach region. However, the intensity of general precipitation and EPE decreased in the Nyangqu River Basin. A total of 43.0% of the area in the YZRB exhibits significant upward trends in EPE frequency. The contributions of EPE to total rainfall increase significantly in the Lhasa and Shannan regions. Overall, it was shown that the risk of disasters from EPE in the YZRB increases in the eastern middle-reach region and southern lower-reach region.

ACS Style

Jiao Fan; Wenchao Sun; Yong Zhao; Baolin Xue; Depeng Zuo; Zongxue Xu. Trend Analyses of Extreme Precipitation Events in the Yarlung Zangbo River Basin, China Using a High-Resolution Precipitation Product. Sustainability 2018, 10, 1396 .

AMA Style

Jiao Fan, Wenchao Sun, Yong Zhao, Baolin Xue, Depeng Zuo, Zongxue Xu. Trend Analyses of Extreme Precipitation Events in the Yarlung Zangbo River Basin, China Using a High-Resolution Precipitation Product. Sustainability. 2018; 10 (5):1396.

Chicago/Turabian Style

Jiao Fan; Wenchao Sun; Yong Zhao; Baolin Xue; Depeng Zuo; Zongxue Xu. 2018. "Trend Analyses of Extreme Precipitation Events in the Yarlung Zangbo River Basin, China Using a High-Resolution Precipitation Product." Sustainability 10, no. 5: 1396.

Journal article
Published: 01 May 2015 in Environmental Research
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Lacking observation data for calibration constrains applications of hydrological models to estimate daily time series of streamflow. Recent improvements in remote sensing enable detection of river water-surface width from satellite observations, making possible the tracking of streamflow from space. In this study, a method calibrating hydrological models using river width derived from remote sensing is demonstrated through application to the ungauged Irrawaddy Basin in Myanmar. Generalized likelihood uncertainty estimation (GLUE) is selected as a tool for automatic calibration and uncertainty analysis. Of 50,000 randomly generated parameter sets, 997 are identified as behavioral, based on comparing model simulation with satellite observations. The uncertainty band of streamflow simulation can span most of 10-year average monthly observed streamflow for moderate and high flow conditions. Nash-Sutcliffe efficiency is 95.7% for the simulated streamflow at the 50% quantile. These results indicate that application to the target basin is generally successful. Beyond evaluating the method in a basin lacking streamflow data, difficulties and possible solutions for applications in the real world are addressed to promote future use of the proposed method in more ungauged basins.

ACS Style

Wenchao Sun; Hiroshi Ishidaira; Satish Bastola; Jingshan Yu. Estimating daily time series of streamflow using hydrological model calibrated based on satellite observations of river water surface width: Toward real world applications. Environmental Research 2015, 139, 36 -45.

AMA Style

Wenchao Sun, Hiroshi Ishidaira, Satish Bastola, Jingshan Yu. Estimating daily time series of streamflow using hydrological model calibrated based on satellite observations of river water surface width: Toward real world applications. Environmental Research. 2015; 139 ():36-45.

Chicago/Turabian Style

Wenchao Sun; Hiroshi Ishidaira; Satish Bastola; Jingshan Yu. 2015. "Estimating daily time series of streamflow using hydrological model calibrated based on satellite observations of river water surface width: Toward real world applications." Environmental Research 139, no. : 36-45.

Research article
Published: 17 February 2014 in The Scientific World Journal
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The influences of climate change on water resources availability in Jinjiang Basin, China, were assessed using the Block-wise use of the TOPmodel with the Muskingum-Cunge routing method (BTOPMC) distributed hydrological model. The ensemble average of downscaled output from sixteen GCMs (General Circulation Models) for A1B emission scenario (medium CO2emission) in the 2050s was adopted to build regional climate change scenario. The projected precipitation and temperature data were used to drive BTOPMC for predicting hydrological changes in the 2050s. Results show that evapotranspiration will increase in most time of a year. Runoff in summer to early autumn exhibits an increasing trend, while in the rest period of a year it shows a decreasing trend, especially in spring season. From the viewpoint of water resource availability, it is indicated that it has the possibility that water resources may not be sufficient to fulfill irrigation water demand in the spring season and one possible solution is to store more water in the reservoir in previous summer.

ACS Style

Wenchao Sun; Jie Wang; Zhanjie Li; Xiaolei Yao; Jingshan Yu. Influences of Climate Change on Water Resources Availability in Jinjiang Basin, China. The Scientific World Journal 2014, 2014, 1 -7.

AMA Style

Wenchao Sun, Jie Wang, Zhanjie Li, Xiaolei Yao, Jingshan Yu. Influences of Climate Change on Water Resources Availability in Jinjiang Basin, China. The Scientific World Journal. 2014; 2014 (282):1-7.

Chicago/Turabian Style

Wenchao Sun; Jie Wang; Zhanjie Li; Xiaolei Yao; Jingshan Yu. 2014. "Influences of Climate Change on Water Resources Availability in Jinjiang Basin, China." The Scientific World Journal 2014, no. 282: 1-7.

Research article
Published: 24 December 2013 in The Scientific World Journal
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Suspended sediment concentration of a river can provide very important perspective on erosion or soil loss of one river basin ecosystem. The changes of land use and land cover, such as deforestation or afforestation, affect sediment yield process of a catchment through changing the hydrological cycle of the area. A sediment rating curve can describe the average relation between discharge and suspended sediment concentration for a certain location. However, the sediment load of a river is likely to be undersimulated from water discharge using least squares regression of log-transformed variables and the sediment rating curve does not consider temporal changes of vegetation cover. The Normalized Difference Vegetation Index (NDVI) can well be used to analyze the status of the vegetation cover well. Thus long time monthly NDVI data was used to detect vegetation change in the past 19 years in this study. Then monthly suspended sediment concentration and discharge from 1988 to 2006 in Laichau station were used to develop one new sediment rating curve and were validated in other Asian basins. The new sediment model can describe the relationship among sediment yield, streamflow, and vegetation cover, which can be the basis for soil conservation and sustainable ecosystem management.

ACS Style

Jie Wang; Hiroshi Ishidaira; Wenchao Sun; ShaoWei Ning. Development and Interpretation of New Sediment Rating Curve Considering the Effect of Vegetation Cover for Asian Basins. The Scientific World Journal 2013, 2013, 1 -9.

AMA Style

Jie Wang, Hiroshi Ishidaira, Wenchao Sun, ShaoWei Ning. Development and Interpretation of New Sediment Rating Curve Considering the Effect of Vegetation Cover for Asian Basins. The Scientific World Journal. 2013; 2013 (4):1-9.

Chicago/Turabian Style

Jie Wang; Hiroshi Ishidaira; Wenchao Sun; ShaoWei Ning. 2013. "Development and Interpretation of New Sediment Rating Curve Considering the Effect of Vegetation Cover for Asian Basins." The Scientific World Journal 2013, no. 4: 1-9.