scholarly journals Accretion–Erosion Dynamics of the Yellow River Delta and the Relationships with Runoff and Sediment from 1976 to 2018

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2992
Author(s):  
He Li ◽  
Chong Huang ◽  
Qingsheng Liu ◽  
Gaohuan Liu
Keyword(s):  
Growth Rate ◽  
Yellow River ◽  
Yellow River Delta ◽  
Annual Growth ◽  
The Yellow River ◽  
Annual Growth Rate ◽  
Land Area ◽  
The Yellow River Delta ◽  
The Yrd

Timely understanding of the coastal accretion–erosion dynamics of the Yellow River Delta (YRD) can not only deepen the understanding of the evolution of the delta but also provide scientific support for water-sediment regulation (WSR) in the lower reaches of Yellow River and the implementation of a protection strategy for the Yellow River Estuary. In this long-term study, Landsat images from 1976 to 2018 were acquired, and the cloud processing platform of the Google Earth Engine was used for extraction of coastlines. On the basis of these coastlines, the area and accretion–erosion dynamics were analyzed. Then, after statistical analysis of the interannual and intra-annual variations in runoff and sediment, we discuss the relationship between the accretion–erosion dynamics and the annual runoff and sediment. The results show that (1) the coastline of the YRD lengthened first and then shortened, and the average annual growth rate was 1.48 km/a. (2) The land area of the YRD showed a significant accretionary trend before 1996, with an average annual growth rate of 28.60 km2/a. Then, the area gradually decreased from 1997 to 2001. After WSR was implemented in 2002, the accretion–erosion dynamics gradually became smooth, with an annual growth rate of 0.31 km2/a. (3) After WSR, the maximum annual sedimentation decreased by 79.70%. The average annual sediment discharge accounted for only 6.69% from November to March of the following year during the non-flood season. (4) With the continuous decrease in sediment discharge, the determination coefficient (R2) between the cumulative accretion–erosion area of the estuary and the annual sedimentation decreased from 0.98 in 1976–1996 to 0.77 after 2002. Overall, although WSR has maintained a steady increase in delta land area, it cannot change the long-term decrease in the land area of the delta. The insights gained from our study can provide some references for related coastline research, and will be useful to science community and decision makers for coastal environmental monitoring, management, protection, and sustainable development of the YRD.

scholarly journals Impacts of Consolidation Time on the Critical Hydraulic Gradient of Newly Deposited Silty Seabed in the Yellow River Delta

2021 ◽  
Vol 9 (3) ◽  
pp. 270
Author(s):  
Meiyun Tang ◽  
Yonggang Jia ◽  
Shaotong Zhang ◽  
Chenxi Wang ◽  
Hanlu Liu
Keyword(s):  
Yellow River ◽  
Yellow River Delta ◽  
Hydraulic Gradient ◽  
River Delta ◽  
Theoretical Formula ◽  
The Yellow River ◽  
The Yellow River Delta ◽  
Critical Hydraulic Gradient ◽  
Seepage Flows ◽  
The Yrd

The silty seabed in the Yellow River Delta (YRD) is exposed to deposition, liquefaction, and reconsolidation repeatedly, during which seepage flows are crucial to the seabed strength. In extreme cases, seepage flows could cause seepage failure (SF) in the seabed, endangering the offshore structures. A critical condition exists for the occurrence of SF, i.e., the critical hydraulic gradient (icr). Compared with cohesionless sands, the icr of cohesive sediments is more complex, and no universal evaluation theory is available yet. The present work first improved a self-designed annular flume to avoid SF along the sidewall, then simulated the SF process of the seabed with different consolidation times in order to explore the icr of newly deposited silty seabed in the YRD. It is found that the theoretical formula for icr of cohesionless soil grossly underestimated the icr of cohesive soil. The icr range of silty seabed in the YRD was 8–16, which was significantly affected by the cohesion and was inversely proportional to the seabed fluidization degree. SF could “pump” the sediments vertically from the interior of the seabed with a contribution to sediment resuspension of up to 93.2–96.8%. The higher the consolidation degree, the smaller the contribution will be.

scholarly journals Regional estimation of daily to annual regional evapotranspiration with MODIS data in the Yellow River Delta wetland

2009 ◽  
Vol 13 (10) ◽  
pp. 1775-1787 ◽  
Author(s):  
L. Jia ◽  
G. Xi ◽  
S. Liu ◽  
C. Huang ◽  
Y. Yan ◽  
...  
Keyword(s):  
Time Series ◽  
Energy Balance ◽  
Land Surface ◽  
Yellow River ◽  
Yellow River Delta ◽  
The Yellow River ◽  
Vegetation Types ◽  
The Yellow River Delta ◽  
Regional Evapotranspiration ◽  
The Yrd

Abstract. Evapotranspiration (ET) from the wetland of the Yellow River Delta (YRD) is one of the important components in the water cycle, which represents the water consumption by the plants and evaporation from the water and the non-vegetated surfaces. Reliable estimates of the total evapotranspiration from the wetland is useful information both for understanding the hydrological process and for water management to protect this natural environment. Due to the heterogeneity of the vegetation types and canopy density and of soil water content over the wetland (specifically over the natural reserve areas), it is difficult to estimate the regional evapotranspiration extrapolating measurements or calculations usually done locally for a specific land cover type. Remote sensing can provide observations of land surface conditions with high spatial and temporal resolution and coverage. In this study, a model based on the Energy Balance method was used to calculate daily evapotranspiration (ET) using instantaneous observations of land surface reflectance and temperature from MODIS when the data were available on clouds-free days. A time series analysis algorithm was then applied to generate a time series of daily ET over a year period by filling the gaps in the observation series due to clouds. A detailed vegetation classification map was used to help identifying areas of various wetland vegetation types in the YRD wetland. Such information was also used to improve the parameterizations in the energy balance model to improve the accuracy of ET estimates. This study showed that spatial variation of ET was significant over the same vegetation class at a given time and over different vegetation types in different seasons in the YRD wetland.

scholarly journals Regional estimation of daily to annual evapotranspiration with MODIS data in the Yellow River Delta wetland

2009 ◽  
Vol 6 (2) ◽  
pp. 2301-2335 ◽  
Author(s):  
L. Jia ◽  
G. Xi ◽  
S. Liu ◽  
C. Huang ◽  
Y. Yan ◽  
...  
Keyword(s):  
Time Series ◽  
Energy Balance ◽  
Land Surface ◽  
Yellow River ◽  
Yellow River Delta ◽  
River Delta ◽  
The Yellow River ◽  
Vegetation Types ◽  
The Yellow River Delta ◽  
The Yrd

Abstract. Evapotranspiration (ET) from the wetland of the Yellow River Delta is one of the important components in the water cycle, which represents the water consumption by the plants and evaporation from the water and the non-vegetated surfaces. Reliable estimates of the total evapotranspiration from the wetland is useful information both for understanding the hydrological process and for water management to protect this natural environment. Due to the heterogeneity of the vegetation types and canopy density and of soil water content over the wetland (specifically over the natural reserve areas), it is difficult to estimate the regional evapotranspiration extrapolating measurements or calculations usually done locally for a specific land cover type. Remote sensing can provide observations of land surface conditions with high spatial and temporal resolution and coverage. In this study, a model based on the Energy Balance method was used to calculate daily ET using instantaneous observations of land surface reflectance and temperature from MODIS when the data were available on clouds-free days. A time series analysis algorithm is then applied to generate a time series of daily ET over a year period by filling the gaps in the observation series due to clouds. A detailed vegetation classification map is used to help identifying areas of various wetland vegetation types in the YRD wetland. Such information is also used to improve the parameterizations in the energy balance model to improve the accuracy of ET estimates. This study shows that spatial variation of ET is significant over the same vegetation class at a given time and over different vegetation types in different seasons in the YRD wetland.

scholarly journals Species composition and long-term variation of macrobenthos in intertidal zone and offshore areas of the Yellow River Delta

2020 ◽  
Vol 28 (12) ◽  
pp. 1511-1522
Author(s):  
Baoquan Li ◽  
Shaoyu Jiang ◽  
Juanzhang Lü ◽  
Linlin Chen ◽  
Lang Yan ◽  
...  
Keyword(s):  
Species Composition ◽  
Intertidal Zone ◽  
Yellow River ◽  
Yellow River Delta ◽  
River Delta ◽  
The Yellow River ◽  
The Yellow River Delta ◽  
Term Variation

scholarly journals Study on Spatiotemporal Evolution of the Yellow River Delta Coastline from 1976 to 2020

2021 ◽  
Vol 13 (23) ◽  
pp. 4789
Author(s):  
Chengming Li ◽  
Lining Zhu ◽  
Zhaoxin Dai ◽  
Zheng Wu
Keyword(s):  
Environmental Sustainability ◽  
Yellow River ◽  
Reduction Rate ◽  
Yellow River Delta ◽  
River Delta ◽  
The Yellow River ◽  
Land Area ◽  
The Yellow River Delta ◽  
Delta Coastline ◽  
Coastline Evolution

The Yellow River Delta in China is the most active one for sea–land changes over all deltas worldwide, and its coastline evolution is critical to urban planning and environmental sustainability in coastal areas. Existing studies rarely used yearly temporal resolution, and lack more detailed and quantitative analysis of coastline evolution characteristics. This paper used visual interpretation to extract the coastline of the Yellow River Delta in year interval Landsat images for 45 years from 1976 to 2020, and analyzed the spatiotemporal characteristics of the coastline evolution through statistical methods such as calculating change values and change rate. The main results are as follows: (1) overall, the coastline of the Yellow River Delta presented a spatial pattern involving northern landward retreat and southern seaward expansion. Since 1990, the Yellow River Delta has entered a period of decline. In addition, the length of the artificial coastline increased by about 55 km; (2) in the Qingshuigou region, the land area and the coastline length increased first and then stabilized. The southeastern part of the Qingshuigou was in a state of erosion, while the northeastern part was expanding toward the sea along the north direction; (3) in the Diaokou region, the land area has been decreasing, but the reduction rate has gradually slowed down. The main conclusions are as follows: (1) through the research on the evolution model and mechanism of the coastline of the Yellow River Delta, it was found that human factors and natural factors were the two major driving factors that affect the evolution of the coastline; (2) a river branch appeared in the northern part of the Qingshuigou region in 2014 and became a major branch in 2020, which would affect the development of the coastal region of Chengdao. This study is important for better understanding the evolution pattern of the Yellow River Delta coastline and will help to provide guidance for coastline management and resource exploitation.

scholarly journals Four Decades of Estuarine Wetland Changes in the Yellow River Delta Based on Landsat Observations Between 1973 and 2013

Water ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 933 ◽  
Author(s):  
Changming Zhu ◽  
Xin Zhang ◽  
Qiaohua Huang
Keyword(s):  
Time Series ◽  
Yellow River ◽  
Yellow River Delta ◽  
River Delta ◽  
Evolution Process ◽  
The Yellow River ◽  
The Yellow River Delta ◽  
The Past ◽  
Spatio Temporal

Yellow River Delta wetlands are essential for the migration of endangered birds and breeding. The wetlands, however, have been severely damaged during recent decades, partly due to the lack of wetland ecosystem protection by authorities. To have a better historical understanding of the spatio-temporal dynamics of the wetlands, this study aims to map and characterize patterns of the loss and degradation of wetlands in the Yellow River Delta using a time series of remotely sensed images (at nine points in time) based on object-based image analysis and knowledge transfer learning technology. Spatio-temporal analysis was conducted to document the long-term changes taking place in different wetlands over the four decades. The results showed that the Yellow River Delta wetlands have experienced significant changes between 1973 and 2013. The total area of wetlands has been reduced by 683.12 km2 during the overall period and the trend of loss continues. However, the rates and trends of change for the different types of wetlands were not the same. The natural wetlands showed a statistically significant decrease in area during the overall period (36.04 km2·year−1). Meanwhile, the artificial wetlands had the opposite trend and showed a statistically significant increase in area during the past four decades (18.96 km2·year−1). According to the change characteristics revealed by the time series wetland classification maps, the evolution process of the Yellow River Delta wetlands could be divided into three stages: (1) From 1973–1984, basically stable, but with little increase; (2) from 1984–1995, rapid loss; and (3) from 1995–2013, slow loss. The area of the wetlands reached a low point around 1995, and then with a little improvement, the regional wetlands entered a slow loss stage. It is believed that interference by human activities (e.g., urban construction, cropland creation, and oil exploitation) was the main reason for wetland degradation in the Yellow River Delta over the past four decades. Climate change also has long-term impacts on regional wetlands. In addition, due to the special geographical environment, the hydrological and sediment conditions and the location of the Yellow River mouth also have a significant influence on the evolution process of the wetlands.

scholarly journals Monitoring the seasonal dynamics of soil salinization in the Yellow River delta of China using Landsat data

2019 ◽  
Vol 19 (7) ◽  
pp. 1499-1508 ◽  
Author(s):  
Hongyan Chen ◽  
Gengxing Zhao ◽  
Yuhuan Li ◽  
Danyang Wang ◽  
Ying Ma
Keyword(s):  
Soil Salinity ◽  
Seasonal Dynamics ◽  
Yellow River ◽  
Yellow River Delta ◽  
Soil Salinization ◽  
Support Vector ◽  
The Yellow River ◽  
Landsat Data ◽  
The Yellow River Delta ◽  
The Yrd

Abstract. In regions with distinct seasons, soil salinity usually varies greatly by season. Thus, the seasonal dynamics of soil salinization must be monitored to prevent and control soil salinity hazards and to reduce ecological risk. This article took the Kenli District in the Yellow River delta (YRD) of China as the experimental area. Based on Landsat data from spring and autumn, improved vegetation indices (IVIs) were created and then applied to inversion modeling of the soil salinity content (SSC) by employing stepwise multiple linear regression, back propagation neural network and support vector machine methods. Finally, the optimal SSC model in each season was extracted, and the spatial distributions and seasonal dynamics of SSC within a year were analyzed. The results indicated that the SSC varied by season in the YRD, and the support vector machine method offered the best SSC inversion models for the precision of the calibration set (R2>0.72, RMSE < 6.34 g kg−1) and the validation set (R2>0.71, RMSE < 6.00 g kg−1 and RPD > 1.66). The best SSC inversion model for spring could be applied to the SSC inversion in winter (R2 of 0.66), and the best model for autumn could be applied to the SSC inversion in summer (R2 of 0.65). The SSC exhibited a gradual increasing trend from the southwest to northeast in the Kenli District. The SSC also underwent the following seasonal dynamics: soil salinity accumulated in spring, decreased in summer, increased in autumn and reached its peak at the end of winter. This work provides data support for the control of soil salinity hazards and utilization of saline–alkali soil in the YRD.

Sign in / Sign up

Export Citation Format

Share Document