Reclamation and River Training in the Qiantang Estuary

Author(s):  
Han Zengcui ◽  
Dai Zeheng
Keyword(s):  
2021 ◽  
Vol 11 (4) ◽  
pp. 1486
Author(s):  
Cuiping Kuang ◽  
Yuhua Zheng ◽  
Jie Gu ◽  
Qingping Zou ◽  
Xuejian Han

Groins are one of the popular manmade structures to modify the hydraulic flow and sediment response in river training. The spacing between groins is a critical consideration to balance the channel-depth and the cost of construction, which is generally determined by the backflow formed downstream from groins. A series of experiments were conducted using Particle Image Velocimetry (PIV) to observe the influence of groin spacing on the backflow pattern of two bilateral groins. The spacing between groins has significant effect on the behavior of the large-scale recirculation cell behind groins. The magnitude of the wake flow induced by a groin was similar to that induced by another groin on the other side, but the flow direction is opposite. The spanwise velocity near the groin tip dictates the recirculation zone width behind the groins due to the strong links between the spanwise velocity and the contraction ratio of channel cross-sections between groins. Based on previous studies and present experimental results, quantitative empirical relationships are proposed to calculate the recirculation zone length behind groins alternately placed at different spacing along riverbanks. This study provides better understanding and a robust formula to assess the backflow extent of alternate groins and identify the optimum groins array configuration.


2020 ◽  
pp. 993-1001
Author(s):  
T. Kašpar ◽  
P. Fošumpaur ◽  
M. Králík ◽  
M. Zukal

2014 ◽  
pp. 1571-1577 ◽  
Author(s):  
N Werdenberg ◽  
M Mende ◽  
C Sindelar
Keyword(s):  

Author(s):  
Adam Łajczak

Abstract Changes in flood risk impacted by river training - case study of piedmont section of the Vistula river. Main problems concerning the flood risk in piedmont section of the Vistula, Southern Poland, are discussed. This stretch of the river is channelized since the middle of the 19th century. It is part of the mainstream discussion of the effectiveness of existing river channelization methods. The following problems are analysed: (1) current state of flood risk, (2) the rate of river flow, (3) changes in flood risk since the start of channelization efforts with respect to changing channel geometry and changing rates of river flow reflecting the effects of channelization work. Substantially increased bankfull discharge in a channelized river may be considered as a stable hydrologic feature of the river stretch analysed. This means that the river is effectively reducing the quantity of water available for flooding the inter-embankment zone. This statement is the basis for analysis of changes in flood risk in the river studied. An assessment of changes in flood risk for the piedmont section of the Vistula cannot be categorical. Some changes in discharge help reduce flood risk, while others increase it. The paper is based mainly on the State Hydrological Survey data over more than the last 100 years, a large-scale maps over the last 230 years, and fieldwork conducted by the author.


2020 ◽  
Vol 54 (3) ◽  
pp. 58-67
Author(s):  
Jia Ni ◽  
Linwei Wang ◽  
Xixian Chen ◽  
Luan Luan Xue ◽  
Isam Shahrour

AbstractFish-bone type dividing dikes are river engineering structures used for river training and to protect a mid-channel bar from scour. The flow characteristics around fish-bone type dividing dikes are very complicated, especially near its fish-bone dam. To understand the flow and scour processes associated with fish-bone dams, this paper conducts a numerical simulation of flow characteristics for different fish-bone dam angles. Based on the Yudaizhou fish-bone type dividing dike of the Dongliu Waterway, a 3-D numerical model is established via Flow-3D to simulate the flow characteristics around a fish-bone type dividing dike, which is verified by flume experiments. Based on the results, the effects of different fish-bone dam angles on water level and velocity distribution are investigated. With increasing fish-bone dam angle, the longitudinal and lateral gradients of the water level gradually decreased, and the variation degree of the longitudinal velocity also decreased; however, the variation degree of the lateral velocity increased. Vortex areas formed around the fish-bone dam and the downstream zone of the dike. A large velocity gradient was found around the dike, and the downstream vortex area decreased with increasing fish-bone dam angle.


Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3018 ◽  
Author(s):  
Knut Oberhagemann ◽  
A. M. Aminul Haque ◽  
Angela Thompson

Protecting against riverbank erosion along the world’s largest rivers is challenging. The Bangladesh Delta, bisected by the Brahmaputra River (also called the Jamuna River), is rife with complexity. Here, an emerging middle-income country with the world’s highest population density coexists with the world’s most unpredictable and largest braided, sand-bed river. Bangladesh has struggled over decades to protect against the onslaught of a continuously widening river corridor. Many of the principles implemented successfully in other parts of the world failed in Bangladesh. To this end, Bangladesh embarked on intensive knowledge-based developments and piloted new technologies. After two decades, successful, sustainable, low-cost riverbank protection technology was developed, suitable for the challenging river conditions. It was necessary to accept that no construction is permanent in this morphologically dynamic environment. What was initially born out of fund shortages became a cost-effective, systematic and adaptive approach to riverbank protection using improved knowledge, new materials, and new techniques, in the form of geobag revetments. This article provides an overview of the challenges faced when attempting to stabilize the riverbanks of the mighty rivers of Bangladesh. An overview of the construction of the major bridge crossings as well as riverbank protection schemes is detailed. Finally, a summary of lessons learned concludes the impressive progress made.


2017 ◽  
Vol 35 (1) ◽  
pp. 63-72 ◽  
Author(s):  
Justyna Hachoł ◽  
Mateusz Hämmerling ◽  
Elżbieta Bondar-Nowakowska

AbstractThe aim of the following study was to compare a few methods of river regulations and indicate the one which fully meets technical regulative standard and concurrently ensures protection of the watercourse ecosystem. According to the sustainable development rules it is of the most importance in every human activity to compromise between developmental and environmental needs of current and future generations. Therefore, both technical criteria related to flood safety and environmental ones were taken into consideration in the analysis. Field study was conducted in vegetation stage between 2008 and 2014 in small and medium lowland watercourses in Lower Silesia. The research comprised of measurements and descriptions of selected technical and environmental elements of a complex system of the watercourse river bed. Basing on obtained results a multicriterial assessment of the effects of the works was conducted. In order to assess the results an Analytic Hierarchy Process (AHP) was used in the study. It facilitated the creation of linear ranking of river beds and indicate the most optimal solution in terms of sustainable development. Such methods have not been applied in solving problems connected with river regulation. That’s why this study aims also at checking the utility of this method in decision making in both planning and regulation works realization. Results of the study indicate high usefulness of AHP method in the decision-making process.


2013 ◽  
Vol 12 ◽  
pp. 66-75
Author(s):  
Achyut Man Singh

A timeline study since 1976-2010 with satellite imagery maps on the flooding problems of Eastern Chitwan has revealed that due to the rapid degradation of the vegetative cover in the upper catchments of its rivers, increased flooding events had occurred. The conditions of the catchment environment depend on the behavior and activities of the people residing in the area. Infrastructure construction for the flood control in the river banks are short term solutions only effective for a few years. For a long term solution, the people of the area need to be sensitive for the river training works and good watershed management. The study has emphasized social and institutional aspect along with awareness campaign with the populations to achieve good impacts in the long term. Hydro Nepal; Journal of Water, Energy and Environment Vol. 12, 2013, January Page: 66-75DOI: http://dx.doi.org/10.3126/hn.v12i0.9035 Uploaded Date : 10/29/2013


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