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Chao Qin
State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China

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Journal article
Published: 06 July 2021 in Remote Sensing
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River discharge and width, as essential hydraulic variables and hydrological data, play a vital role in influencing the water cycle, driving the resulting river topography and supporting ecological functioning. Insights into bankfull river discharge and bankfull width at fine spatial resolutions are essential. In this study, 10-m Sentinel-2 multispectral instrument (MSI) imagery and digital elevation model (DEM) data, as well as in situ discharge and sediment data, are fused to extract bankfull river widths on the upper Yellow River. Using in situ cross-section morphology data and flood frequency estimations to calculate the bankfull discharge of 22 hydrological stations, the one-to-one correspondence relationship between the bankfull discharge data and the image cover data was determined. The machine learning (ML) method is used to extract water bodies from the Sentinel-2 images in the Google Earth Engine (GEE). The mean overall accuracy was above 0.87, and the mean kappa value was above 0.75. The research results show that (1) for rivers with high suspended sediment concentrations, the water quality index (SRMIR-Red) constitutes a higher contribution; the infrared band performs better in areas with greater amounts of vegetation coverage; and for rivers in general, the water indices perform best. (2) The effective river width of the extracted connected rivers is 30 m, which is 3 times the image resolution. The R2, root mean square error (RMSE), and mean bias error (MBE) of the estimated river width values are 0.991, 7.455 m, and −0.232 m, respectively. (3) The average river widths of the single-thread sections show linear increases along the main stream, and the R2 value is 0.801. The river width has a power function relationship with bankfull discharge and the contributing area, i.e., the downstream hydraulic geometry, with R2 values of 0.782 and 0.630, respectively. More importantly, the extracted river widths provide basic data to analyze the spatial distribution of bankfull widths along river networks and other applications in hydrology, fluvial geomorphology, and stream ecology.

ACS Style

Dan Li; Ge Wang; Chao Qin; Baosheng Wu. River Extraction under Bankfull Discharge Conditions Based on Sentinel-2 Imagery and DEM Data. Remote Sensing 2021, 13, 2650 .

AMA Style

Dan Li, Ge Wang, Chao Qin, Baosheng Wu. River Extraction under Bankfull Discharge Conditions Based on Sentinel-2 Imagery and DEM Data. Remote Sensing. 2021; 13 (14):2650.

Chicago/Turabian Style

Dan Li; Ge Wang; Chao Qin; Baosheng Wu. 2021. "River Extraction under Bankfull Discharge Conditions Based on Sentinel-2 Imagery and DEM Data." Remote Sensing 13, no. 14: 2650.

Journal article
Published: 01 June 2021 in Water Resources Research
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At-many-stations hydraulic geometry (AMHG) has provided a novel way to understand river network development, simulate water flow, and retrieve river discharge in data-scared regions. Based on in-situ measurements of six major rivers originating from the Qinghai-Tibet Plateau (QTP), this study verifies the existence of AMHG relations along the rivers and explores AMHG relations for cross sections that are not located in the same river reach. The mainstreams and tributaries of the studied rivers in the southern and the eastern portions of the QTP have satisfactory AMHG relation strengths with R2 > 0.9 for over 60% of the relations. For cross sections located in the same stream order or within a certain range of contributing area (CA), approximately 60% (9/15) and 53% (8/15) of the AMHG relations have an R2 > 0.6. AMHG strength increases with increasing stream order and CA; this finding reflects the increasing coherence and maturity of the river networks associated with the geomorphic shaping power of increased discharge. Width-AMHG intercepts are larger than those of depth-AMHG and velocity-AMHG for all stream orders and CAs. Most of the congruent hydraulics generated from cross sections located in middle-scale rivers (orders 7–8) are within the observed range. Congruent hydraulics generally increase with an increase in in-situ measured hydraulics when the stream order or the CA increases. The AMHG relations existing among cross sections that are not located in the same reach, which is named as cross channel AMHG, indicate linear variability of cross-sectional geometric and hydraulic similarities in the same stream order or within a certain CA range. The results break the watershed divide boundary control on AMHG and have the potential to provide background knowledge for discharge estimation in mountain rivers located in the QTP.

ACS Style

Chao Qin; Baosheng Wu; Guangqian Wang; Ge Wang. Spatial Distributions of At‐Many‐Stations Hydraulic Geometry for Mountain Rivers Originated From the Qinghai‐Tibet Plateau. Water Resources Research 2021, 57, 1 .

AMA Style

Chao Qin, Baosheng Wu, Guangqian Wang, Ge Wang. Spatial Distributions of At‐Many‐Stations Hydraulic Geometry for Mountain Rivers Originated From the Qinghai‐Tibet Plateau. Water Resources Research. 2021; 57 (6):1.

Chicago/Turabian Style

Chao Qin; Baosheng Wu; Guangqian Wang; Ge Wang. 2021. "Spatial Distributions of At‐Many‐Stations Hydraulic Geometry for Mountain Rivers Originated From the Qinghai‐Tibet Plateau." Water Resources Research 57, no. 6: 1.

Journal article
Published: 24 August 2020 in Remote Sensing
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Water is essential for the survival of plants, animals, and human beings. It is imperative to effectively manage and protect aquatic resources to sustain life on Earth. Small tributaries are an important water resource originating in mountain areas, they play an important role in river network evolution and water transmission and distribution. Snow and cloud cover cast shadows leading to misclassification in optical remote sensing images, especially in high-mountain regions. In this study, we effectively extract small and open-surface river information in the Upper Yellow River by fusing Sentinel-2 with 10 m resolution optical imagery corresponding to average discharge of the summer flood season and the 90 m digital elevation model (DEM) data. To effectively minimize the impact of the underlying surface, the study area was divided into five sub-regions according to underlying surface, terrain, and altitude features. We minimize the effects of cloud, snow, and shadow cover on the extracted river surface via a modified normalized difference water index (MNDWI), revised normalized difference water index (RNDWI), automated water extraction index (AWEI), and Otsu threshold method. Water index calculations and water element extractions are operated on the Google Earth Engine (GEE) platform. The river network vectors derived from the DEM data are used as constraints to minimize background noise in the extraction results. The accuracy of extracted river widths is assessed using different statistical indicators such as the R-square (R2) value, root mean square error (RMSE), mean bias error (MBE). The results show the integrity of the extracted small river surface by the RNDWI index is optimal. Overall, the statistical evaluation indicates the accuracy of the extracted river widths is satisfactory. The effective river width that can be accurately extracted based on satellite images is three times the image resolution. Sentinel-2 MSI images with a spatial resolution of 10 m are used to find that the rivers over 30 m wide can be connectedly, accurately extracted with the proposed method. Results of this work can enrich the river width database in the northeast Tibetan Plateau and its boundary region. The river width information may provide a foundation for studying the spatiotemporal changes in channel geometry of river systems in high-mountain regions. They can also supplement the necessary characteristic river widths information for the river network in unmanned mountain areas, which is of great significance for the accurate simulation of the runoff process in the hydrological model.

ACS Style

Dan Li; Baosheng Wu; Bowei Chen; Chao Qin; Yanjun Wang; Yi Zhang; Yuan Xue. Open-Surface River Extraction Based on Sentinel-2 MSI Imagery and DEM Data: Case Study of the Upper Yellow River. Remote Sensing 2020, 12, 2737 .

AMA Style

Dan Li, Baosheng Wu, Bowei Chen, Chao Qin, Yanjun Wang, Yi Zhang, Yuan Xue. Open-Surface River Extraction Based on Sentinel-2 MSI Imagery and DEM Data: Case Study of the Upper Yellow River. Remote Sensing. 2020; 12 (17):2737.

Chicago/Turabian Style

Dan Li; Baosheng Wu; Bowei Chen; Chao Qin; Yanjun Wang; Yi Zhang; Yuan Xue. 2020. "Open-Surface River Extraction Based on Sentinel-2 MSI Imagery and DEM Data: Case Study of the Upper Yellow River." Remote Sensing 12, no. 17: 2737.

Research article
Published: 16 July 2020 in Earth Surface Processes and Landforms
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Rill network development not only potentially affects hillslope and drainage network evolution, but also causes severe soil degradation. However, the studies on rill network development remain inconclusive. This study aimed to investigate the temporal and spatial development of hillslope rill networks and their characteristics based on rainfall simulations and field observations. A soil pan (10.0 m long × 3.0 m wide × 0.5 m deep) on a 20° slope was applied three successive simulated rains at two intensities of 50 and 100 mm h–1. The field observations were performed on two bare hillslope runoff plots (10.0 m long × 3.0 m wide) at 20°. Three typical erosive natural rainfall events were observed in the field, and rills were measured in detail, similar to the lab rainfall simulation. The results indicated that with increases in rainfall events, the rill network morphology varied from incipient formation to the maximum drainage network density. Four rill network development indicators (rill distribution density, distance between rills, rill bifurcation number, and confluence point number) exhibited different changes over time and space. Among the four indicators, the rill bifurcation number was the best indicator for describing rill network development. Rill flow energy increased and decreased cyclically on a slope ranging between ~3–4 m. Moreover, rill networks on loessial hillslopes generally evolved into dendritic rather than parallel forms. The development characteristics of the rill network were relatively similar between the lab simulation and natural field conditions. Over time, rill erosion control measures become increasingly difficult to implement as the rill network develops. The morphology of eroding rills evolved over time and space, which led to corresponding rill network development. Further study should quantify the impacts of rill network development on soil degradation and land development.

ACS Style

Haiou Shen; Fenli Zheng; Xun‐Chang (John) Zhang; Chao Qin. Rill network development on loessial hillslopes in China. Earth Surface Processes and Landforms 2020, 45, 3178 -3184.

AMA Style

Haiou Shen, Fenli Zheng, Xun‐Chang (John) Zhang, Chao Qin. Rill network development on loessial hillslopes in China. Earth Surface Processes and Landforms. 2020; 45 (13):3178-3184.

Chicago/Turabian Style

Haiou Shen; Fenli Zheng; Xun‐Chang (John) Zhang; Chao Qin. 2020. "Rill network development on loessial hillslopes in China." Earth Surface Processes and Landforms 45, no. 13: 3178-3184.

Journal article
Published: 09 June 2020 in CATENA
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To be able to precisely estimate discharges in un-gaged streams and reconstruct hydrological features in river systems, the temporal and spatial variations of at-a-station hydraulic geometry (AHG) and their impacting factors need to be detected. To this end, the Yalong River and Upper Jinsha River, which located in southeast Qinghai-Tibet Plateau, are selected as case study. This investigation explores quantitative data on the magnitude of spatial and temporal variations in AHGs over a period of 10 years for 38 mountain reaches with drainage areas ranging from 0.53 × 103 to 259.18 × 103 km2. Effects of ice regime and drainage area on AHG were discussed and the stability of AHG was analyzed. 42.1% of the reaches have flow velocity exponents that are greater than the river width and flow depth exponents combined. No significant spatial variation tendency is observed for AHG exponents while significant temporal variations are reported. Larger fluctuations are found for AHG exponents in annual variations compared with those in inter-annual variations. Ice regimes significantly contribute to the seasonal changes of AHGs. The relative differences of AHG coefficients (a, c, k) and exponents (b, f, m) with and without ice vary between −49.4 to 80.8% and −70.1% to 22.6%, respectively. Compared with no ice regime, the reaches with border ice and slush ice run have smaller exponents m and Froude Number and larger coefficients c and exponents f. Besides, coefficients a and exponents m increase while coefficients k and exponents b decrease with the increase of drainage area. However, coefficients c and exponents f exhibit no tendency with drainage area changes. AHG stabilities increase with the increased stream order and drainage area. Results of this study can enrich the AHG database for mountain rivers and provide a preliminary understanding of ice effects on AHG variations.

ACS Style

Chao Qin; Baosheng Wu; Yanjun Wang; Xudong Fu; Yuan Xue; Dan Li; Minhui Li; Yi Zhang. Dynamic variability of at-a-station hydraulic-geometry for mountain rivers in the southeast Qinghai-Tibet Plateau: The cases of Yalong River and upper Jinsha River. CATENA 2020, 194, 104723 .

AMA Style

Chao Qin, Baosheng Wu, Yanjun Wang, Xudong Fu, Yuan Xue, Dan Li, Minhui Li, Yi Zhang. Dynamic variability of at-a-station hydraulic-geometry for mountain rivers in the southeast Qinghai-Tibet Plateau: The cases of Yalong River and upper Jinsha River. CATENA. 2020; 194 ():104723.

Chicago/Turabian Style

Chao Qin; Baosheng Wu; Yanjun Wang; Xudong Fu; Yuan Xue; Dan Li; Minhui Li; Yi Zhang. 2020. "Dynamic variability of at-a-station hydraulic-geometry for mountain rivers in the southeast Qinghai-Tibet Plateau: The cases of Yalong River and upper Jinsha River." CATENA 194, no. : 104723.

Preprint content
Published: 09 March 2020
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Channel widening constitutes about 80% of total soil loss, especially in the presence of a plow pan which manifests a less or nonerodible soil layer. Channel bank erosion quantification is prerequisite to couple effectively the bank sediment supply system with fluvial sediment transport fluxes. The objectives of this study were to: 1) describe and evaluate methods for monitoring and data post-analysis of channel widening and 2) investigate how inflow rate, slope gradient and initial channel width affect channel widening processes in the presence of a non-erodible layer. Technology was developed to capture 5-cm spaced cross-sections along a soil flume at 3-s time intervals. Two off-the-shelf digital cameras were positioned 3-m above the soil bed and controlled by a program to trigger simultaneously and download images to the computer. Methods utilizing color differences in images and elevation differences in DEMs were applied to detect discontinuities between channel walls and the soil bed. Channel widths were calculated by differentiating the coordinates of these surface discontinuities. A volumetric method was used to calculate flow velocity with measurements of flow depths obtained from ultrasonic depth sensors. Sediment concentration was determined by manual sampling.

The results showed that different channel width calculation methods exhibited comparable outcomes and achieved satisfactory accuracy. Sediment discharge showed a significant positive linear correlation with channel widening rate, while exhibiting a 5 to 25-s time lag compared to the peak of channel widening rate. Total sediment discharge calculated by photogrammetry was 3.1% lower than that calculated by manual sampling. Flow velocity decreased with time and showed a significant negative power correlation with channel width. Sediment delivery and channel width increased with the increase of inflow rate, bed slope and the decrease of initial channel width. Exponential equations were used to predict the channel width time series. Toe scour, crack development, sidewall failure and block detachment and transport, in sequence, were the four main processes of channel widening. Basal scour arc length, tension crack length and width decreased with initial channel width and increased with time, flow discharge and bed slope. Basal scour arcs were divided into three patterns according to different shapes in comparison to the failure arcs. Sediment delivery equations based on the disaggregation of concentrated flow entrainment and mass failure were also fitted. Advantages of the described methodology include automated high spatial and temporal monitoring resolution, semi-automated data post-processing, and the potential to be generalized to large scale river/reservoir bank failure monitoring. This study provides new insight on improving channel widening measurements and prediction technology.

ACS Style

Chao Qin; Fenli Zheng; Robert Wells. Channel widening quantification under laboratory conditions. 2020, 1 .

AMA Style

Chao Qin, Fenli Zheng, Robert Wells. Channel widening quantification under laboratory conditions. . 2020; ():1.

Chicago/Turabian Style

Chao Qin; Fenli Zheng; Robert Wells. 2020. "Channel widening quantification under laboratory conditions." , no. : 1.

Preprint content
Published: 09 March 2020
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Water plays a vital role in plants, animals and human survival, as well as water resources planning and protection. The spatial and temporal changes of rivers have a profound impact on climate change and the scientific protection of the regional ecological environment in Qingzang-Tibet plateau. Due to the influence of snow and cloud cover, optical remote sensing images in this region have less effective coverage. Many researches in the past mainly faced the challenge of misclassification caused by shadows from cloud and mountain. In this study, we proposed a method to improve the extraction of rivers by reducing the effect of shadows by fusing Sentinel-1 radar data and Sentinel-2 optical imagery. For the optical imagery, water indices including MNDWI (Modified Normalized Difference Water Index) and RNDWI (Revised Normalized Difference Water Index) and morphological operations were used to extract the river coverage. In addition, radar data is used to extract water in areas where there is no optical image coverage or where optical images are misclassified by using a combination of both the histogram and Otsu threshold methods. The GEE (Google Earth Engine) platform is used to implement the analysis using two classification datasets at a regional level. Relevant results from Sentinel-1 and Sentinel-2 data showed that the RNDWI has a more accurate water extraction results in this region. We further compared the final river width results with the manually measured samples from Google Earth and situ data of hydrological stations for accuracy assessment. The R2 value is 0.90, and the standard deviation is 18.663m. The river width can be estimated well by this method, which can provide basic data for the study of water in depopulated zone.

Keywords: Remote sensing, shadow removal, water extraction, water index, Otsu threshold, Google Earth Engine

ACS Style

Dan Li; Baosheng Wu; Bowei Chen; Yanjun Wang; Yi Zhang; Yuan Xue; Chao Qin. Fusion of Sentinel-1 radar and Sentinel-2 MSI imagery for water extraction in Tibetan plateau. 2020, 1 .

AMA Style

Dan Li, Baosheng Wu, Bowei Chen, Yanjun Wang, Yi Zhang, Yuan Xue, Chao Qin. Fusion of Sentinel-1 radar and Sentinel-2 MSI imagery for water extraction in Tibetan plateau. . 2020; ():1.

Chicago/Turabian Style

Dan Li; Baosheng Wu; Bowei Chen; Yanjun Wang; Yi Zhang; Yuan Xue; Chao Qin. 2020. "Fusion of Sentinel-1 radar and Sentinel-2 MSI imagery for water extraction in Tibetan plateau." , no. : 1.

Journal article
Published: 13 June 2019 in CATENA
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Channels (rill, ephemeral gully, gully and river channel) exhibit a continuum of sizes and flow magnitudes. Rill erosion, as the initial stage of channel erosion, accounts for >80% of total eroded sediments on sloping farming lands in many parts of the world. Previous researches often regard rill erosion as an entirety or focus on individual rill erosion process separately. Few attentions have been paid to the contributions of individual processes including rill headcut advance, bed incision, sidewall expansion and their interactions to the over-all rill erosion. Thus, simulated upslope inflow experiments were designed to investigate the impacts of individual processes involved and their interactions in rill erosion under four inflow rates (1.0, 2.0, 3.0 and 4.0 L min−1) and two slope gradients (15° and 20°). Photogrammetry and manual sampling were used to measure hillslope morphology variation and sediment delivery, repectively. The results show that headcut advance, bed incision and sidewall expansion interact with each other and exhibit both independent and dependent features across spatial and temporal scales. Headcut advance interacts with bed incision and sidewall expansion before rill head advancing to a critical slope length. Initial rill depth and width are determined by initial headcut morphology. Bed incision and sidewall expansion dominate rill erosion before and after the non-erodible layer is exposed to concentrated flow, respectively. Headcut advance contributed the largest amount of rill erosion (44%–68%), followed by bed incision (27%–44%) and sidewall expansion (3.8%–12%). Headcut advance contributed more (63%–83%) to total rill width increment while bed incision contributed larger percentage (51%–65%) to total rill depth increment. Prediction equations for length, width and depth of a single rill on a loessial hillslope and empirical equations of rill erosion for the individual erosion processes were fitted and validated. Quantification and understanding of the contributions of individual rill erosion processes provides the necessary scientific basis for the development of process-based rill erosion models, and then, for preventions of soil losses and land degradation.

ACS Style

Chao Qin; Fenli Zheng; Glenn V. Wilson; Xunchang J. Zhang; Ximeng Xu. Apportioning contributions of individual rill erosion processes and their interactions on loessial hillslopes. CATENA 2019, 181, 104099 .

AMA Style

Chao Qin, Fenli Zheng, Glenn V. Wilson, Xunchang J. Zhang, Ximeng Xu. Apportioning contributions of individual rill erosion processes and their interactions on loessial hillslopes. CATENA. 2019; 181 ():104099.

Chicago/Turabian Style

Chao Qin; Fenli Zheng; Glenn V. Wilson; Xunchang J. Zhang; Ximeng Xu. 2019. "Apportioning contributions of individual rill erosion processes and their interactions on loessial hillslopes." CATENA 181, no. : 104099.

Journal article
Published: 30 April 2019 in Soil and Tillage Research
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Accurate soil erosion monitoring provides a basis for soil erosion prediction and prevention. Channel bank erosion quantification is prerequisite to couple effectively the bank sediment supply system with fluvial sediment transport fluxes. The objectives of this study were to describe and evaluate methods for monitoring and data post-analysis of channel widening in the presence of a non-erodible layer. Technology was developed to capture 5-cm spaced cross-sections along a soil flume at 3-s time intervals. Two off-the-shelf digital cameras were positioned 3-m above the soil bed and controlled by a program to trigger simultaneously and download images to the computer. Methods utilizing color differences in images and elevation differences in DEMs were applied to detect discontinuities between channel walls and the soil bed. Channel widths were calculated by differentiating the coordinates of these surface discontinuities. A volumetric method was used to calculate flow velocity with measurements of flow depths obtained from ultrasonic depth sensors. Sediment concentration was determined by manual sampling. The results showed that different channel width calculation methods exhibited comparable outcomes and achieved satisfactory accuracy. Sediment discharge showed a significant positive linear correlation with channel widening rate, while exhibiting a 5 to 25-s time lag compared to the peak of channel widening rate. Total sediment discharge calculated by photogrammetry was 3.1% lower than that calculated by manual sampling. Flow velocity decreased with time and showed a significant negative power correlation with channel width. Advantages of the described methodology include automated high spatial and temporal monitoring resolution, semi-automated data post-processing, and the potential to be generalized to large scale river/reservoir bank failure monitoring.

ACS Style

Chao Qin; Robert R. Wells; Henrique G. Momm; Ximeng Xu; Glenn V. Wilson; Fenli Zheng. Photogrammetric analysis tools for channel widening quantification under laboratory conditions. Soil and Tillage Research 2019, 191, 306 -316.

AMA Style

Chao Qin, Robert R. Wells, Henrique G. Momm, Ximeng Xu, Glenn V. Wilson, Fenli Zheng. Photogrammetric analysis tools for channel widening quantification under laboratory conditions. Soil and Tillage Research. 2019; 191 ():306-316.

Chicago/Turabian Style

Chao Qin; Robert R. Wells; Henrique G. Momm; Ximeng Xu; Glenn V. Wilson; Fenli Zheng. 2019. "Photogrammetric analysis tools for channel widening quantification under laboratory conditions." Soil and Tillage Research 191, no. : 306-316.

Journal article
Published: 29 June 2018 in Journal of Soils and Sediments
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Characterizations of soil aggregates and soil organic carbon (SOC) losses affected by different water erosion patterns at the hillslope scale are poorly understood. Therefore, the objective of this study was to quantify how sheet and rill erosion affect soil aggregates and soil organic carbon losses for a Mollisol hillslope in Northeast China under indoor simulated rainfall. The soil used in this study was a Mollisol (USDA Taxonomy), collected from a maize field (0–20 cm depth) in Northeast China. A soil pan with dimensions 8 m long, 1.5 m wide and 0.6 m deep was subjected to rainfall intensities of 50 and 100 mm h−1. The experimental treatments included sheet erosion dominated (SED) and rill erosion dominated (RED) treatments. Runoff with sediment samples was collected during each experimental run, and then the samples were separated into six aggregate fractions (0–0.25, 0.25–0.5, 0.5–1, 1–2, 2–5, > 5 mm) to determine the soil aggregate and SOC losses. At rainfall intensities of 50 and 100 mm h−1, soil losses from the RED treatment were 1.4 and 3.5 times higher than those from the SED treatment, and SOC losses were 1.7 and 3.8 times greater than those from the SED treatment, respectively. However, the SOC enrichment ratio in sediment from the SED treatment was 1.15 on average and higher than that from the RED treatment. Furthermore, the loss of < 0.25 mm aggregates occupied 41.1 to 73.1% of the total sediment aggregates for the SED treatment, whereas the loss of > 0.25 mm aggregates occupied 53.2 to 67.3% of the total sediment aggregates for the RED treatment. For the organic carbon loss among the six aggregate fractions, the loss of 0–0.25 mm aggregate organic carbon dominated for both treatments. When rainfall intensity increased from 50 to 100 mm h−1, aggregate organic carbon loss increased from 1.04 to 5.87 times for six aggregate fractions under the SED treatment, whereas the loss increased from 3.82 to 27.84 times for six aggregate fractions under the RED treatment. This study highlights the effects of sheet and rill erosion on soil and carbon losses at the hillslope scale, and further study should quantify the effects of erosion patterns on SOC loss at a larger scale to accurately estimate agricultural ecosystem carbon flux.

ACS Style

Yiliang Jiang; Fenli Zheng; Leilei Wen; Hai-Ou Shen. Effects of sheet and rill erosion on soil aggregates and organic carbon losses for a Mollisol hillslope under rainfall simulation. Journal of Soils and Sediments 2018, 19, 467 -477.

AMA Style

Yiliang Jiang, Fenli Zheng, Leilei Wen, Hai-Ou Shen. Effects of sheet and rill erosion on soil aggregates and organic carbon losses for a Mollisol hillslope under rainfall simulation. Journal of Soils and Sediments. 2018; 19 (1):467-477.

Chicago/Turabian Style

Yiliang Jiang; Fenli Zheng; Leilei Wen; Hai-Ou Shen. 2018. "Effects of sheet and rill erosion on soil aggregates and organic carbon losses for a Mollisol hillslope under rainfall simulation." Journal of Soils and Sediments 19, no. 1: 467-477.

Journal article
Published: 01 June 2018 in Atmospheric Research
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ACS Style

Keyuan Zhong; Fenli Zheng; Ximeng Xu; Chao Qin. Discriminating the precipitation phase based on different temperature thresholds in the Songhua River Basin, China. Atmospheric Research 2018, 205, 48 -59.

AMA Style

Keyuan Zhong, Fenli Zheng, Ximeng Xu, Chao Qin. Discriminating the precipitation phase based on different temperature thresholds in the Songhua River Basin, China. Atmospheric Research. 2018; 205 ():48-59.

Chicago/Turabian Style

Keyuan Zhong; Fenli Zheng; Ximeng Xu; Chao Qin. 2018. "Discriminating the precipitation phase based on different temperature thresholds in the Songhua River Basin, China." Atmospheric Research 205, no. : 48-59.

Journal article
Published: 01 June 2018 in CATENA
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Quantifying rill bed incision provides fundamental information for process-based erosion modeling; while the morphodynamic and hydrodynamic mechanism in bed incision processes are still unclear. Thus, experiments were conducted to examine rill bed incision processes in upland concentrated flows. DEMs (2 mm × 2 mm resolution) obtained by photogrammetry were used for rill bed morphology analysis. Rill channel (2.0 m-long, 0.08 m-wide and 0.15 m-deep) with two slope gradients (15° and 20°) were subjected to four overland flow rates (1.0, 2.0, 3.0 and 4.0 L min−1). The results showed that sediment delivery, rill bed incision rate and average rill depth increased with inflow rate and bed slope. Sediment delivery increased from 0.060 to 0.226 kg min−1 per 1 L min−1 inflow increment and from 0.043 to 0.207 kg min−1 when bed slope increased from 15° to 20°. In a well-developed rill channel, rill bed incision could be divided into three phases: pre-headcut formation (dominated by rill flow shear stress), headcut incision (dominated by headcut advancing) and post-headcut incision (dominated by rill flow shear stress). Headcut incision phase, which only accounted for 65% of rill bed sediment. In the pre-headcut formation phase, rill flow velocity, shear stress and stream power increased with increases of inflow rate and slope gradient. Conversely, flow velocity showed no evident trend with increased inflow rate and bed slope during headcut incision phase. Initial headcut advancing rate could be predicted by a non-linear function based upon soil characteristics, rill flow shear stress and headcut height. Sediment delivery showed a power function with the product of inflow rate and squared bed slope. Because rill bed incision is dominated by headcut advancement and incision, practices for controlling headcut initiation should be implemented to decrease hillslope soil loss.

ACS Style

Chao Qin; Fenli Zheng; Xunchang J. Zhang; Ximeng Xu; Gang Liu. A simulation of rill bed incision processes in upland concentrated flows. CATENA 2018, 165, 310 -319.

AMA Style

Chao Qin, Fenli Zheng, Xunchang J. Zhang, Ximeng Xu, Gang Liu. A simulation of rill bed incision processes in upland concentrated flows. CATENA. 2018; 165 ():310-319.

Chicago/Turabian Style

Chao Qin; Fenli Zheng; Xunchang J. Zhang; Ximeng Xu; Gang Liu. 2018. "A simulation of rill bed incision processes in upland concentrated flows." CATENA 165, no. : 310-319.

Journal article
Published: 01 May 2018 in Soil and Tillage Research
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Gully erosion contributes large amounts of sediment within watersheds around the world. Gully widening constitutes about 80% of total soil loss, especially in the presence of a plow pan which manifests a less or non-erodible soil layer. Current knowledge on sidewall toe scour (scour arcs) and tension crack processes in gully widening is limited. Thus, simulated channel sidewall expansion tests, where the channel bed was fixed to represent a non-erodible layer, were designed to investigate how inflow rate, slope gradient and initial channel width affect channel widening processes. Soil boxes (2.0 m-long, 0.3 m-wide and 0.5 m-deep) with two slope gradients (15° and 20°), four inflow rates (1.0, 2.0, 3.0 and 4.0 L min−1) and two initial channel widths (4 and 8 cm) were subjected to clear-water overland flow. Photogrammetry was used to detect tension crack and width variations of channels. The results show that sediment delivery and channel width increase with the increase of inflow rate, bed slope and the decrease of initial channel width. Exponential equations were used to predict the channel width time series. Time lag occurred between sediment peak and soil block failure. Toe scour, crack development, sidewall failure and block detachment and transport, in sequence, were the four main processes of channel widening. Basal scour arc length, tension crack length and width decreased with initial channel width and increased with time, flow discharge and bed slope. Basal scour arcs were divided into three patterns according to different shapes in comparison to the failure arcs. Sediment delivery equations based on the disaggregation of concentrated flow entrainment and mass failure were also fitted. This study provides new insight on improving gully erosion measurements and prediction technology.

ACS Style

Chao Qin; Fenli Zheng; Robert R. Wells; Ximeng Xu; Bin Wang; Keyuan Zhong. A laboratory study of channel sidewall expansion in upland concentrated flows. Soil and Tillage Research 2018, 178, 22 -31.

AMA Style

Chao Qin, Fenli Zheng, Robert R. Wells, Ximeng Xu, Bin Wang, Keyuan Zhong. A laboratory study of channel sidewall expansion in upland concentrated flows. Soil and Tillage Research. 2018; 178 ():22-31.

Chicago/Turabian Style

Chao Qin; Fenli Zheng; Robert R. Wells; Ximeng Xu; Bin Wang; Keyuan Zhong. 2018. "A laboratory study of channel sidewall expansion in upland concentrated flows." Soil and Tillage Research 178, no. : 22-31.

Article
Published: 05 February 2018 in Earth Surface Processes and Landforms
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Gully morphology characteristics can be well used effectively to describe the status of gully development. The Chabagou watershed, located in the hilly-gully region of the Loess Plateau in China, was selected to investigate gully morphological characteristics using 3D laser scanning technique (LIDAR). Thirty-one representative gullies located at different watershed locations and gully orders were chosen to quantitatively describe gully morphology and establish empirical equations for estimating gully volume based on gully length and gully surface area. Images and point cloud data for the 31 gullies were collected, and digital elevation models (DEMs) with 10-cm resolution were generated. ArcGIS 10.1 was then used to extract fundamental gully morphological parameters covering gully length (L), gully width (WT) and gully depth (D), and some derivative morphological parameters, including gully head curvature (C), gully width-depth ratio (w/d), gully bottom-to-top width ratio (WB/WT), gully surface area (Ag) and gully volume (Vg). The results indicated that gullies in the upper watershed and the 2nd order were more developed based on their high values of gully head curvature. The potential for gully development increased from the 2nd order to the 4th order. Within the same gully orders, gullies in the lower watershed were more active with more development potential. A method for differentiating between gully head and gully sidewalls based on the gully head curvature value was proposed with a mean relative error of 8.77%. U-shaped cross-sections were widely distributed in the upper watershed and upper positions of a gully, while V-shaped cross-sections were widely distributed in the lower watershed and lower positions of a gully. V–L and V–Ag empirical equations with acceptable accuracy were established and can be used to estimate gully erosion in the Loess hilly-gully region.

ACS Style

Hongyan Wu; Ximeng Xu; Fenli Zheng; Chao Qin; Xu He. Gully morphological characteristics in the loess hilly-gully region based on 3D laser scanning technique. Earth Surface Processes and Landforms 2018, 43, 1701 -1710.

AMA Style

Hongyan Wu, Ximeng Xu, Fenli Zheng, Chao Qin, Xu He. Gully morphological characteristics in the loess hilly-gully region based on 3D laser scanning technique. Earth Surface Processes and Landforms. 2018; 43 (8):1701-1710.

Chicago/Turabian Style

Hongyan Wu; Ximeng Xu; Fenli Zheng; Chao Qin; Xu He. 2018. "Gully morphological characteristics in the loess hilly-gully region based on 3D laser scanning technique." Earth Surface Processes and Landforms 43, no. 8: 1701-1710.

Journal article
Published: 12 December 2017 in Journal of Soils and Sediments
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Rills are basic pathways for runoff, sediment, and pollutant transport at hillslopes within agricultural watershed. The objectives of this study were to investigate the development processes of rill network and morphological characteristics and to examine their affecting factors. A soil box (10 m long, 1.5 m wide, and 0.5 m deep) was subjected to four successive simulated rains under rainfall intensity of 90 mm h−1 with slope gradients of 15° and 25°. Digital elevation models (5 mm resolution) were created from the terrestrial laser scanning measurements. Total soil loss was 46.3 and 61.0 kg m−2 at the 15° and 25° slope gradients, and rill erosion occupied over 75% of the total soil loss. Soil loss and rill erosion were expressed as power equations to the product of slope gradient and accumulated rainfall. Rill networks evolved in a converging way and reached maturity in the fourth rain. Main rill length and rill width, depth, and degree of contour line departure increased with increased rains, while rill width/depth ratio showed the opposite trend. Secondary rill length and rill density increased in the first two rains, and then both decreased in the latter two rains. Scour effect of lateral interfluve flow and meander cutoffs of rill flow were two sub-processes of rill piracy. Rill length and density decreased due to rill piracy specific in merging of secondary rills into main rills. Plow pan and secondary headcuts played key roles in main rill bed incision and sidewall expansion processes, while both had little impact on secondary rills. Results of this study can improve the understanding of how plow pan, rill piracy, and secondary headcut affect rill network and morphologies and provide fundamental knowledge for designing rill prevention practices.

ACS Style

Chao Qin; Fenli Zheng; Ximeng Xu; Hongyan Wu; Haiou Shen. A laboratory study on rill network development and morphological characteristics on loessial hillslope. Journal of Soils and Sediments 2017, 18, 1679 -1690.

AMA Style

Chao Qin, Fenli Zheng, Ximeng Xu, Hongyan Wu, Haiou Shen. A laboratory study on rill network development and morphological characteristics on loessial hillslope. Journal of Soils and Sediments. 2017; 18 (4):1679-1690.

Chicago/Turabian Style

Chao Qin; Fenli Zheng; Ximeng Xu; Hongyan Wu; Haiou Shen. 2017. "A laboratory study on rill network development and morphological characteristics on loessial hillslope." Journal of Soils and Sediments 18, no. 4: 1679-1690.

Journal article
Published: 01 July 2017 in Atmospheric Research
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Keyuan Zhong; Fenli Zheng; Hongyan Wu; Chao Qin; Ximeng Xu. Dynamic changes in temperature extremes and their association with atmospheric circulation patterns in the Songhua River Basin, China. Atmospheric Research 2017, 190, 77 -88.

AMA Style

Keyuan Zhong, Fenli Zheng, Hongyan Wu, Chao Qin, Ximeng Xu. Dynamic changes in temperature extremes and their association with atmospheric circulation patterns in the Songhua River Basin, China. Atmospheric Research. 2017; 190 ():77-88.

Chicago/Turabian Style

Keyuan Zhong; Fenli Zheng; Hongyan Wu; Chao Qin; Ximeng Xu. 2017. "Dynamic changes in temperature extremes and their association with atmospheric circulation patterns in the Songhua River Basin, China." Atmospheric Research 190, no. : 77-88.

Journal article
Published: 01 February 2017 in CATENA
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Ximeng Xu; Fenli Zheng; Chao Qin; Hongyan Wu; Glenn Wilson. Impact of cornstalk buffer strip on hillslope soil erosion and its hydrodynamic understanding. CATENA 2017, 149, 417 -425.

AMA Style

Ximeng Xu, Fenli Zheng, Chao Qin, Hongyan Wu, Glenn Wilson. Impact of cornstalk buffer strip on hillslope soil erosion and its hydrodynamic understanding. CATENA. 2017; 149 ():417-425.

Chicago/Turabian Style

Ximeng Xu; Fenli Zheng; Chao Qin; Hongyan Wu; Glenn Wilson. 2017. "Impact of cornstalk buffer strip on hillslope soil erosion and its hydrodynamic understanding." CATENA 149, no. : 417-425.

Journal article
Published: 27 September 2014 in Natural Hazards
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Flood, drought, hail, low temperature and frost disasters from low temperature and frost (DLTF), and snowstorm are the five main meteorological disasters (MDs) in China. Based on the collection of historical documents during 1950–2013 and official records between 2012 and 2013, this paper analyzed the temporal trends of affected area induced by MDs during 1950–2013 and the spatiotemporal characteristics of disaster frequency in recent 2 years in China. Besides, the direct economic losses and deaths caused by MDs were further discussed at a provincial level. Results showed that the affected area of MDs, especially flood, drought and DLTF significantly increased during the past 60 years. Flood was the most frequent disaster in China during 2012 and 2013, followed by hail. Spatial patterns of disaster frequency showed that there were more frequent floods in the middle and lower reaches of the Yellow River and the Yangtze River basin, droughts in central and southwest China, hails in north, northwest and southwest China, DLTFs and snowstorms in north, northwest China and individual areas in south China. However, the economic losses caused by MDs were higher in economically developed provinces, and the deaths were higher in mountain regions. Additionally, flood was the major disasters type that contributing to the most losses in most regions of China. These results play an important theoretical guiding role in meteorological disaster prediction, disaster prevention and reduction in the future.

ACS Style

Yinghui Guan; Fenli Zheng; Peng Zhang; Chao Qin. Spatial and temporal changes of meteorological disasters in China during 1950–2013. Natural Hazards 2014, 75, 2607 -2623.

AMA Style

Yinghui Guan, Fenli Zheng, Peng Zhang, Chao Qin. Spatial and temporal changes of meteorological disasters in China during 1950–2013. Natural Hazards. 2014; 75 (3):2607-2623.

Chicago/Turabian Style

Yinghui Guan; Fenli Zheng; Peng Zhang; Chao Qin. 2014. "Spatial and temporal changes of meteorological disasters in China during 1950–2013." Natural Hazards 75, no. 3: 2607-2623.