scholarly journals Runoff and Sediment Response to Cascade Hydropower Exploitation in the Middle and Lower Han River, China

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Junhong Zhang ◽  
Mingkun Sun ◽  
Zhimin Deng ◽  
Jing Lu ◽  
Dangwei Wang ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Sediment Load ◽  
Rapid Development ◽  
Strong Positive Correlation ◽  
Han River ◽  
Runoff Variation ◽  
Impact Index ◽  
Before And After ◽  
Time Periods ◽  
The Impact

With the rapid development of hydropower exploitation in China, changes in runoff and sediment transport have become a significant issue that cannot be neglected. In this study, the Han River was selected as a study case, where the runoff variation and changes in sediment load at the Baihe, Huangjiagang, Huangzhuang, and Xiantao stations were analyzed in different time periods. The results indicate that impact of cascade hydropower exploitation on runoff and sediment transport is significantly different even during the same time periods. After reservoir regulation, the decreasing of sediment load is faster than that of runoff. Strong positive correlation between runoff and sediment load exists during different time periods, while reservoir operation leads to different turning points at the Baihe, Huangjiagang, Huangzhuang, and Xiantao stations in the middle and lower Han River. As a key driving factor, runoff variation contributed to sediment transport with different impact indexCR. The impact indexCRbefore and after the first change point at the Baihe, Huangjiagang, Huangzhuang, and Xiantao stations is 43.35%, −3.68%, 11.17%, and 30.12%, respectively. This study helps us understand and evaluate the hydrological changes under cascade hydropower exploitation in the middle and lower Han River.

scholarly journals The Impact Of Defeasance On Bond Prices

2011 ◽  
Vol 4 (3) ◽  
pp. 15
Author(s):  
James A. Seifert ◽  
David E. Mielke
Keyword(s):  
Financial Markets ◽  
Corporate Debt ◽  
Bond Prices ◽  
Price Changes ◽  
Before And After ◽  
Time Periods ◽  
Changes In Risk ◽  
The Impact

This study reports on the financial markets reaction to the defeasance of corporate debt and whether the market perceives a changes in risk as a result of this activity. The prices of seventeen bonds both before and after defeasance were analyzed using t-tests to determine if any significant price changes related to the act of defeasance occurred between these two time periods. Contrary to what might be expected no significant differences were found.

scholarly journals Response of tidal flow regime and sediment transport in North Male' Atoll, Maldives to coastal modification and sea level rise

2020 ◽  
Author(s):  
Shuaib Rasheed ◽  
Simon C. Warder ◽  
Yves Plancherel ◽  
Matthew D. Piggott
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Sea Level Rise ◽  
Sea Level ◽  
Land Reclamation ◽  
Tidal Flow ◽  
Sediment Grain Size ◽  
Sediment Distribution ◽  
Time Periods ◽  
The Impact

Abstract. Changes to coastlines and bathymetry alter tidal dynamics and associated sediment transport process, impacting upon a number of threats facing coastal regions, including flood risk and erosion. Especially vulnerable are coral atolls such as those that make up the Maldives archipelago which has undergone significant land reclamation in recent years and decades, and is also particularly exposed to sea level rise. Here we develop a tidal model of Male' Atoll, Maldives, and use it to assess potential changes to sediment grain size distributions under sea level rise and coastline alteration scenarios. The results indicate that the impact of coastline modification over the last two decades at the island scale is not limited to the immediate vicinity of the modified island, but can also significantly impact the sediment grain size distribution across the wider atoll basin. Additionally, the degree of change in sediment distribution which can be associated with sea level rise that is projected to occur over relatively long time periods is predicted to occur over far shorter time periods with coastline changes, highlighting the need to better understand, predict and mitigate the impact of land reclamation and other coastal modifications before conducting such activities.

Nonstationary frequency analysis for annual runoff and sediment load of the Wujiang River

2020 ◽  
Author(s):  
Rongrong Li
Keyword(s):  
River Basin ◽  
Human Activities ◽  
Sediment Load ◽  
Heavy Rain ◽  
Annual Runoff ◽  
Statistical Characteristics ◽  
Explanatory Variables ◽  
Wujiang River ◽  
Before And After ◽  
The Impact

<p>The hydrological series can no longer meet the stationarity hypothesis due to the influence of climate variability and human activities. The process of runoff and sediment load changed significantly under a changing environment. Analyzing the variations of runoff and sediment load and exploring the main influencing causes leading to their changes will be of great help to understand the dynamic process of water and sediment in river basin. Many studies have considered the effects of rainfall and reservoir on the downstream runoff or sediment: the impact of rainfall on runoff or sediment load is normally performed by comparing the statistical characteristics before and after an extreme weather event (e.g. heavy rain of the Yangtze river in 1998); the effect of reservoirs is usually determined by comparing the pre-dam and post-dam frequencies of runoff or sediment load. In this study, the major influencing factors of annual runoff and sediment load in Wujiang River basin were identified firstly based on the results of trend analysis and change-point diagnosis for runoff and sediment load. Then, Generalized Addictive Models in Location, Scale, and Shape (GAMLSS) is used to describe the rainfall and reservoir impacts on nonstationarity of runoff and sediment load, in which, distribution parameters (including the location, scale and shape parameter) are expressed as a function of the explanatory variables. The results show that: (1) runoff and sediment load of Wujiang River decrease with the intensification of climate change and human activities; (2) runoff is mainly affected by rainfall, the operation of cascade reservoirs has critical effect on the sediment load; (3) the correlation between runoff and sediment closely related to the nonstationarity of sediment load, namely, the sediment load change can directly lead to the alteration of dependence between runoff and sediment.</p>

scholarly journals Response of tidal flow regime and sediment transport in North Malé Atoll, Maldives, to coastal modification and sea level rise

Ocean Science ◽  
2021 ◽  
Vol 17 (1) ◽  
pp. 319-334
Author(s):  
Shuaib Rasheed ◽  
Simon C. Warder ◽  
Yves Plancherel ◽  
Matthew D. Piggott
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Sea Level Rise ◽  
Sea Level ◽  
Land Reclamation ◽  
Transport Processes ◽  
Sediment Grain Size ◽  
Sediment Distribution ◽  
Time Periods ◽  
The Impact

Abstract. Changes to coastlines and bathymetry alter tidal dynamics and associated sediment transport processes, impacting upon a number of threats facing coastal regions, including flood risk and erosion. Especially vulnerable are coral atolls such as those that make up the Maldives archipelago, which has undergone significant land reclamation in recent years and decades and is also particularly exposed to sea level rise. Here we develop a tidal model of Malé Atoll, Maldives, the first atoll-scale and multi-atoll-scale high-resolution numerical model of the atolls of the Maldives and use it to assess potential changes to sediment grain size distributions in the deeper atoll basin, under sea level rise and coastline alteration scenarios. The results indicate that the impact of coastline modification over the last two decades at the island scale is not limited to the immediate vicinity of the modified island but can also significantly impact the sediment grain size distribution across the wider atoll basin. Additionally, the degree of change in sediment distribution which can be associated with sea level rise that is projected to occur over relatively long time periods is predicted to occur over far shorter time periods with coastline changes, highlighting the need to better understand, predict and mitigate the impact of land reclamation and other coastal modifications before conducting such activities.

scholarly journals The upper Odra as a case study of the impact of channel regulation on its morphodynamics

2014 ◽  
Vol 46 (4) ◽  
pp. 353-361
Author(s):  
Agnieszka Czajka
Keyword(s):  
Sediment Transport ◽  
Material Transport ◽  
Channel Dynamics ◽  
Channel Regulation ◽  
Before And After ◽  
Odra River ◽  
The One ◽  
Bed Material ◽  
The Impact

Abstract The upper Odra as a case study of the impact of channel regulation on its morphodynamics. The aim of the research was to compare morphodynamics of the Odra river channel in three different sectors and to find the main difference in the way of sediment transport before and after regulation in meandering, straight and sinuous channel sectors and compare the data with those calculated for reconstructed, natural channel of the Odra river. Sediment transport in discussed sectors was compared for average, bankfull and flood discharges and it proceeds in different ways. Morphodynamics of the preregulated Odra was most similar to the one currently observed in the meandering section. Also the dynamics of bed-material transport and, consequently, the possibility of the occurrence and disappearance of channel forms is greatly varied among the studied sectors. As it was assumed, a diversified channel geometry imposes water flow, which entails a series of processes shaping the channel dynamics.

REGIONAL DEVELOPMENT DYNAMICS IN INDONESIA BEFORE AND AFTER THE ‘BIG BANG’ DECENTRALIZATION

2016 ◽  
Vol 61 (02) ◽  
pp. 1640027 ◽  
Author(s):  
HAL HILL ◽  
YOGI VIDYATTAMA
Keyword(s):  
Regional Development ◽  
Local Level ◽  
Rapid Development ◽  
National Level ◽  
Big Bang ◽  
Spatial Inequality ◽  
Minimal Impact ◽  
Before And After ◽  
The Big Bang ◽  
The Impact

Decentralization is in vogue. However, the relationship between decentralization and local-level development dynamics remains unclear. Does decentralization lead to a ‘reform dividend’ of more rapid development in better-governed regions, with attendant national benefits? What is the impact on spatial inequality? In particular, do poorer regions lag further behind as equalizing fiscal policies at the national level weaken? We address these issues with reference to Indonesia, the world’s largest archipelagic nation, which implemented a ‘big bang’ decentralization program in 2001. Our main conclusion, perhaps counterintuitive, is that decentralization had a minimal impact on regional development dynamics, although its political impacts have been far-reaching.

The effect of bidding success in construction bidding

2012 ◽  
Vol 19 (1) ◽  
pp. 25-39 ◽  
Author(s):  
Bee Lan Oo ◽  
Hing‐Po Lo ◽  
Benson Teck‐Heng Lim
Keyword(s):  
Content Type ◽  
Capacity Level ◽  
Bid Price ◽  
Before And After ◽  
Construction Firm ◽  
Time Periods ◽  
The Individual ◽  
The Impact ◽  
Bidding Behaviour ◽  
Over Time

PurposeWinning a bid will carry implications for capacity level of a construction firm. This paper aims to examine the impact of a winning bid on contractors' bid pricing strategies.Design/methodology/approachIn identifying the specific types of bidding trends before and after a winning bid, the variations in bids are expressed as a function of time relative to winning bid – the “event” of interest in this study – using a piecewise mixed effects model. The bids analysed comprised series of bids with a winning bid in between, recorded from Hong Kong building contractors.FindingsThe results show that there is a relationship between bid price and bidding success. The bidders in general bid low for time periods before a winning bid and they are less competitive in time periods after a winning bid. However, by considering the individual bidders' characteristics that relate to differences in bidding competitiveness, it is shown that there is remarkable heterogeneity among the bidders in bid pricing decision for pre‐ and post‐winning periods. Nevertheless, the statistically significant bidding trends before and after a winning bid strengthen the notion that systematic changes in bidding behaviour over time do occur in reality in response to changes in firm capacity level.Originality/valueThis empirical investigation provides strong evidence on the systematic changes in bidding behaviour over time in response to changes in firm capacity level, supporting the need to incorporate firm capacity level in the future development of a suitable theoretical framework on construction bidding.

Decline of sediment transport due to damming and eco-engineering is approaching its limits

2021 ◽  
Author(s):  
Boyan Li ◽  
Yunchen Wang ◽  
Chao Wang ◽  
Wei Wang ◽  
Aiwen Lin ◽  
...  
Keyword(s):  
Climate Change ◽  
Sediment Transport ◽  
Soil Erosion ◽  
River Basin ◽  
Water Conservation ◽  
Human Activities ◽  
Sediment Load ◽  
Yangtze River Basin ◽  
Sensitivity Index ◽  
The Impact

Abstract Sediment transport from rivers to ocean is increasingly influenced by climate change and intensive human activities1, constituting a research priority of global relevance2. However, little attention has been paid to quantify and predict the contribution of driving factors to the sediment load. By integrating local-scale hydrologic modeling with soil erosion estimation model, and the soil erosion and sediment yield balance equation, we quantify watershed-scale changes in sediment load under forecasted climate change and human activities in the Yangtze River Basin (YRB), China. We also develop a new metric, the sediment load sensitivity index, that identifies sensitive to anthropogenic variability over the past 30 years. It was found that the reservoirs deposition was the primary factor (81.37 %) among human activities contributing to the decline in sediment load, followed by the soil and water conservation measures (SWCM) (18.63 %). The sediment load shows a slight increasing trend for the 1.5 °C and 2.0 °C global warming at 2020–2039 and 2040–2059, respectively. Climate change dominates the sediment load trend in the future due to the effectiveness of dams and reservoirs decreases and the saturation of the capacity of the SWCM to capture sediment. Although these findings indicate the importance of the impact of climate change on changes in sediment load, it is necessary to apply them to appropriate management to adapt to climate changes in future river basin management policies.

Experimental Investigation of the Impact of Dual Time Periods on Crash Hazardous Location Identification

ICCTP 2011 ◽  
2011 ◽  
Author(s):  
Gilbert Leano ◽  
Wen Cheng ◽  
Xudong Jia ◽  
Lingqi Kong ◽  
Robert Brennan
Keyword(s):  
Experimental Investigation ◽  
Time Periods ◽  
Location Identification ◽  
The Impact

Research on behavior recognition based on feature fusion of automatic coder and recurrent neural network

2020 ◽  
Vol 39 (6) ◽  
pp. 8927-8935
Author(s):  
Bing Zheng ◽  
Dawei Yun ◽  
Yan Liang
Keyword(s):  
Neural Network ◽  
Recurrent Neural Network ◽  
Behavior Pattern ◽  
Rapid Development ◽  
Video Data ◽  
Support Vector ◽  
Behavior Recognition ◽  
Learning Methods ◽  
The Impact ◽  
Internet Of Things Technology

Under the impact of COVID-19, research on behavior recognition are highly needed. In this paper, we combine the algorithm of self-adaptive coder and recurrent neural network to realize the research of behavior pattern recognition. At present, most of the research of human behavior recognition is focused on the video data, which is based on the video number. At the same time, due to the complexity of video image data, it is easy to violate personal privacy. With the rapid development of Internet of things technology, it has attracted the attention of a large number of experts and scholars. Researchers have tried to use many machine learning methods, such as random forest, support vector machine and other shallow learning methods, which perform well in the laboratory environment, but there is still a long way to go from practical application. In this paper, a recursive neural network algorithm based on long and short term memory (LSTM) is proposed to realize the recognition of behavior patterns, so as to improve the accuracy of human activity behavior recognition.

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