scholarly journals Water level characteristics of Lake Caizi, lower reaches of the Yangtze River during wintering period based on long-term hydrological alteration

2019 ◽  
Vol 31 (6) ◽  
pp. 1662-1669
Author(s):  
LIU Xuewen ◽  
◽  
LI Hongqing ◽  
YANG Yinqun ◽  
ZHONG Xia ◽  
...  
Keyword(s):  
Water Level ◽  
Yangtze River ◽  
The Yangtze River ◽  
Hydrological Alteration

scholarly journals Evolution characteristics and drivers of the water level at an identical discharge in the Jingjiang reaches of the Yangtze River

2020 ◽  
Vol 30 (10) ◽  
pp. 1633-1648
Author(s):  
Yuanfang Chai ◽  
Yunping Yang ◽  
Jinyun Deng ◽  
Zhaohua Sun ◽  
Yitian Li ◽  
...  
Keyword(s):  
Water Level ◽  
Yangtze River ◽  
The Yangtze River ◽  
Evolution Characteristics

scholarly journals Seasonal behaviour of tidal damping and residual water level slope in the Yangtze River estuary: identifying the critical position and river discharge for maximum tidal damping

2019 ◽  
Vol 23 (6) ◽  
pp. 2779-2794 ◽  
Author(s):  
Huayang Cai ◽  
Hubert H. G. Savenije ◽  
Erwan Garel ◽  
Xianyi Zhang ◽  
Leicheng Guo ◽  
...  
Keyword(s):  
Water Level ◽  
River Discharge ◽  
Yangtze River ◽  
River Estuary ◽  
Yangtze River Estuary ◽  
Residual Water ◽  
The Yangtze River ◽  
The Yangtze River Estuary ◽  
Seasonal Behaviour ◽  
Residual Water Level

Abstract. As a tide propagates into the estuary, river discharge affects tidal damping, primarily via a friction term, attenuating tidal motion by increasing the quadratic velocity in the numerator, while reducing the effective friction by increasing the water depth in the denominator. For the first time, we demonstrate a third effect of river discharge that may lead to the weakening of the channel convergence (i.e. landward reduction of channel width and/or depth). In this study, monthly averaged tidal water levels (2003–2014) at six gauging stations along the Yangtze River estuary are used to understand the seasonal behaviour of tidal damping and residual water level slope. Observations show that there is a critical value of river discharge, beyond which the tidal damping is reduced with increasing river discharge. This phenomenon is clearly observed in the upstream part of the Yangtze River estuary (between the Maanshan and Wuhu reaches), which suggests an important cumulative effect of residual water level on tide–river dynamics. To understand the underlying mechanism, an analytical model has been used to quantify the seasonal behaviour of tide–river dynamics and the corresponding residual water level slope under various external forcing conditions. It is shown that a critical position along the estuary is where there is maximum tidal damping (approximately corresponding to a maximum residual water level slope), upstream of which tidal damping is reduced in the landward direction. Moreover, contrary to the common assumption that larger river discharge leads to heavier damping, we demonstrate that beyond a critical value tidal damping is slightly reduced with increasing river discharge, owing to the cumulative effect of the residual water level on the effective friction and channel convergence. Our contribution describes the seasonal patterns of tide–river dynamics in detail, which will, hopefully, enhance our understanding of the nonlinear tide–river interplay and guide effective and sustainable water management in the Yangtze River estuary and other estuaries with substantial freshwater discharge.

scholarly journals Variation of the Water Level in the Yangtze River in Response to Natural and Anthropogenic Changes

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2594 ◽  
Author(s):  
Jinxin Liu ◽  
Jinyun Deng ◽  
Yuanfang Chai ◽  
Yunping Yang ◽  
Boyuan Zhu ◽  
...  
Keyword(s):  
Water Level ◽  
Yangtze River ◽  
Dry Season ◽  
Climate Variation ◽  
Dominant Factor ◽  
The Yangtze River ◽  
Flood Season ◽  
Dam Operation ◽  
Adjustment Mechanisms ◽  
Measured Water

The water level in the Yangtze River has significantly changed due to the effects of varied precipitation and dam operations, which have exerted significant effects on irrigation, navigation, and ecosystems. Based on the measured data and the proposed calculation method, we analyzed the adjustment mechanisms of the seasonal water level in the whole Yangtze River. The results were as follows. During the dry season, the rising precipitation and dam operation both increased the water level in the upper reaches and in the reaches from the Jianli to Datong stations during 1981–2014. Moreover, dam operations were the dominant factor (except at Datong station). In the reaches from the Yichang to Shashi stations, dam operations are the reason for the reduction of the measured water level in the dry season, while the rising precipitation had an opposite influence. During the flood season, dam operations helped to reduce the water level from the upper reaches to the estuary during 1981–2014, while climate variation stresses adversely affected the entire river basin. In the reaches between the Luoshan and Jianli stations, climate variation is the dominant factor for the increased water level during the flood season, while dam operation is the reason for the reduced water level at the other six hydrological stations.

scholarly journals Monitoring Temporal Change of River Islands in the Yangtze River by Remotely Sensed Data

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1484 ◽  
Author(s):  
Jinyan Sun ◽  
Lei Ding ◽  
Jiaze Li ◽  
Haiming Qian ◽  
Mengting Huang ◽  
...  
Keyword(s):  
Water Level ◽  
Yangtze River ◽  
Temporal Change ◽  
Flood Disaster ◽  
Water Levels ◽  
Sediment Supply ◽  
The Yangtze River ◽  
Flood Warning ◽  
River Islands ◽  
The Impact

The spatial extent and area of river islands are always changing due to the impact of hydrodynamic conditions, sediment supply and human activities. A catastrophic flood disaster was driven by sustained and heavy rainfall around the middle and lower Yangtze River in 18 June to 21 July 2016. The flood resulted in the most serious social-economic loss since 1954 and caused a larger-scale inundation for a short time. It is essential to continuously monitor the dynamics changes of river islands because this can avoid frequent field measurements in river islands before and after flood disasters, which are helpful for flood warning. This paper focuses on the temporal change of three river islands called Fenghuangzhou, Changshazhou, and one uninhabited island in the Yangtze River in 2016. In this study, GF-1 (GaoFen-1) WFV (wide field view) data was used for our study owing to its fine spatial and temporal resolution. A simple NDWI (Normalized Difference Water Index) method was used for the river island mapping. Human checking was then performed to ensure mapping accuracy. We estimated the relationship between the area of river islands and measured water levels using four models. Furthermore, we mapped the spatial pattern of inundation risk of river islands. The results indicate a good ability of the GF-1 WFV data with a 16-m spatial resolution to characterize the variation of river islands and to study the association between flood disaster and river islands. A significantly negative but nonlinear relationship between the water level and the area of the river island was observed. We also found that the cubic function fits best among three models (R2 > 0.8, P < 0.001). The maximum of the inundated area at the river island appeared in the rainy season on 8 July 2016 and the minimum occurred in the dry season on 28 December 2016, which is consistent with the water level measured by the hydrological station. Our results derived from GF-1 data can provide a useful reference for decision-making of flood warning, disaster assessment, and post-disaster reconstruction.

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