scholarly journals Conceptual Model for Simulating the Adjustments of Bankfull Characteristics in the Lower Yellow River, China

2014 ◽  
Vol 2014 ◽  
pp. 1-12
Author(s):  
Yuanjian Wang ◽  
Xudong Fu ◽  
Guangqian Wang

We present a conceptual model for simulating the temporal adjustments in the banks of the Lower Yellow River (LYR). Basic conservation equations for mass, friction, and sediment transport capacity and the Exner equation were adopted to simulate the hydrodynamics underlying fluvial processes. The relationship between changing rates in bankfull width and depth, derived from quasiuniversal hydraulic geometries, was used as a closure for the hydrodynamic equations. On inputting the daily flow discharge and sediment load, the conceptual model successfully simulated the 30-year adjustments in the bankfull geometries of typical reaches of the LYR. The square of the correlating coefficient reached 0.74 for Huayuankou Station in the multiple-thread reach and exceeded 0.90 for Lijin Station in the meandering reach. This proposed model allows multiple dependent variables and the input of daily hydrological data for long-term simulations. This links the hydrodynamic and geomorphic processes in a fluvial river and has potential applicability to fluvial rivers undergoing significant adjustments.

2015 ◽  
Vol 14 (8) ◽  
pp. 1933-1939
Author(s):  
Xianqi Zhang ◽  
Weiwei Han ◽  
Xiaofei Peng ◽  
Cundong Xu

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 338
Author(s):  
Chuanshun Zhi ◽  
Wengeng Cao ◽  
Zhen Wang ◽  
Zeyan Li

High–arsenic (As) groundwater poses a serious threat to human health. The upper and middle reaches of the Yellow River are well–known areas for the enrichment of high–arsenic groundwater. However, little is known about the distribution characteristics and formation mechanism of high-As groundwater in the lower reach of the Yellow River. There were 203 groundwater samples collected in different groundwater systems of the lower Yellow River for the exploration of its hydrogeochemical characteristics. Results showed that more than 20% of the samples have arsenic concentrations exceeding 10 μg/L. The high-As groundwater was mainly distributed in Late Pleistocene–Holocene aquifers, and the As concentrations in the paleochannels systems (C2 and C4) were significantly higher than that of the paleointerfluve system (C3) and modern Yellow River affected system (C5). The high-As groundwater is characterized by high Fe2+ and NH4+ and low Eh and NO3−, indicating that reductive dissolution of the As–bearing iron oxides is probably the main cause of As release. The arsenic concentrations strikingly showed an increasing tendency as the HCO3− proportion increases, suggesting that HCO3− competitive adsorption may facilitate As mobilization, too. In addition, a Gibbs diagram showed that the evaporation of groundwater could be another significant hydrogeochemical processes, except for the water–rock interaction in the study area. Different sources of aquifer medium and sedimentary structure may be the main reasons for the significant zonation of the As spatial distribution in the lower Yellow River.


2021 ◽  
Vol 316 ◽  
pp. 107468
Author(s):  
Zhigang Sun ◽  
Shiji Li ◽  
Kangying Zhu ◽  
Ting Yang ◽  
Changxiu Shao

2017 ◽  
Vol 42 (13) ◽  
pp. 1952-1962 ◽  
Author(s):  
Jie Li ◽  
Junqiang Xia ◽  
Meirong Zhou ◽  
Shanshan Deng ◽  
Xiaolei Zhang

Land ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 712
Author(s):  
Kaifeng Li ◽  
Wenhua Gao ◽  
Li Wu ◽  
Hainan Hu ◽  
Panpan Gong ◽  
...  

Obvious spatial expansion of human settlement occurred in the lower Yellow River floodplain during the Longshan period, but the external factors driving this expansion remain unclear. In this study, we first delineated the hydroclimatic changes at both regional and local scales within and around the lower Yellow River floodplain and then examined the relationships of human settlements with hydroclimatic settings between the pre-Longshan and Longshan periods. The results indicate that the site distribution, site density and hydroclimatic conditions exhibited significant shifts during the pre-Longshan and Longshan periods. In the pre-Longshan period, the intense East Asian summer monsoon and abundant monsoon-related precipitation caused widespread development of lakes and marshes in the lower Yellow River floodplain. As a result, the circumjacent highlands of the lower Yellow River floodplain contained concentrated human settlements. However, the persistent weakening of the East Asian summer monsoon and consequent precipitation decline, in conjunction with accelerated soil erosion due to decreasing forest vegetation and strengthening of human activities on the upstream Loess Plateau in the Longshan period, are likely to have jointly caused both shrinking and faster filling of preexisting lakes and marshes. Subsequently, a large area of arable land had been created in the lower Yellow River floodplain and thus was occupied by locally rapid increasing population, resulting in the notable spatial expansion of human settlements during the Longshan period.


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