Hasil untuk "River, lake, and water-supply engineering (General)"

WANG Yi-sen, ZHOU Zhi-wei, LI Zhi-jing, LI Da-zhi, JIN Zhong-wu

[Objective] For water intake projects, the arrangement of the intake location is of paramount importance, as it must ensure the required water diversion volume while simultaneously preventing excessive sediment from entering the diversion channels and power station turbines. This balance is critical for the smooth operation of water diversion and power generation at the station. This study specifically focuses on the water diversion and sediment control challenges at the intake hub of the Central Yunnan Water Diversion Project. [Methods] Physical model testing was utilized, whereby a normal model of a 5.5 km river reach from Bachawan to Ma’anshan was established. The model primarily simulated the transport of suspended sediment, with the time scale serving as the primary control parameter for the experiments. The main objectives were to analyze the impact of project construction on flow and sediment transport within the study reach and the sediment deposition within the diversion channel. [Results] (1) Channel flow velocity and patterns were influenced by inflow conditions and morphological resistance. Higher separation walls effectively isolated flow in the left and right channels, regulated flow toward the respective pump stations, promoted smoother flow within the channel, and enhanced sediment settling.(2) In the Jinsha River, flood peak flows were characterized by short duration, while medium and low flow conditions persisted for longer periods. Since identical intake locations and shapes were adopted in both long and short separation wall schemes, their effects on flow and sediment movement had negligible differences.(3) Under medium and low flow conditions, flow control at the pump stations was easier with the long separation wall scheme. It also produced a smaller recirculation zone and a more uniform velocity distribution across the cross-section. When the flow exceeded 2 180 m3/s, the short separation wall scheme exhibited slightly lower velocities in both the left and right channels of the diversion channel than those for the long wall scheme. The main flow zone in the right channel narrowed, and the recirculation zone expanded. However, overall, the flow patterns in the diversion channel showed minimal differences between the two separation wall schemes.(4) Under high flow with high sediment load conditions, sediment began to deposit immediately downstream of the intake and progressively increased along the channel, while the sediment concentration in the flow gradually decreased. No significant difference in sediment concentrations entering the pump stations was detected between the long and short separation wall schemes. Sediment particle size was coarser at the channel intake entrance but finer at the pump station inlets due to in-channel deposition. [Conclusion] Although the long separation wall scheme exhibits slightly higher total volume of sediment deposition compared to the short separation wall scheme, it demonstrates superior accessibility for channel inspection and sediment dredging. Therefore, the long wall scheme is recommended as the preferred scheme. The proposed scheme, integrating a diversion wall with a long separation wall, has been adopted for construction and operation. For the low-head reach water diversion project in the Jinsha River in Yunnan, a hub layout that combines the convex bank diversion with internal flow separation within the diversion channel is an effective solution for sediment control. This approach offers a valuable reference for similar projects.

Lumin Hong, Guangwei Huang

Abstract The paper aimed to better characterize how flood impacts have changed over time in Japan. It is hypothesized that different flood impact indicators vary in their sensitivity to significant changes. To test this hypothesis, change‐point analysis was applied to various indicators, including flood‐related deaths, the ratio of deaths to total flood victims, and a newly proposed composite indicator that integrates both loss of life and property damage. The analysis revealed that while the annual number of flood victims has remained statistically unchanged during the study period, the proportion of deaths among victims has increased. Similarly, although the annual number of completely damaged houses did not show a significant change, the proportion of completely damaged houses relative to the total number of flooded houses has risen. According to the newly developed composite indicator, the overall impact of flooding in Japan has shifted upward since 2004. The value of this study lies in its novel approach of combining loss of life with property damage in trend analysis, enabling policymakers and citizens to better understand the evolving risks posed by floods. These findings not only provide policymakers with a comprehensive reference for evaluating the effectiveness of flood management measures but also help promote public participation in flood mitigation efforts.

Ran Gong, Hui-ya Wang, Zhi-xin Hu et al.

Nutrient release from sediment is considered a significant source for overlying water. Given that nutrient release mechanisms in sediment are complex and difficult to simulate, traditional approaches commonly use assigned parameter values to simulate these processes. In this study, a nitrogen flux model was developed and coupled with the water quality model of an urban lake. After parameter sensitivity analyses and model calibration and validation, this model was used to simulate nitrogen exchange at the sediment–water interface in eight scenarios. The results showed that sediment acted as a buffer in the sediment–water system. It could store or release nitrogen at any time, regulate the distribution of nitrogen between sediment and the water column, and provide algae with nitrogen. The most effective way to reduce nitrogen levels in urban lakes within a short time is to reduce external nitrogen loadings. However, sediment release might continue to contribute to the water column until a new balance is achieved. Therefore, effective measures for reducing sediment nitrogen should be developed as supplementary measures. Furthermore, model parameter sensitivity should be individually examined for different research subjects.

LIANG Yuanyuan

In order to understand the variation characteristics of the annual maximum flood flow at the main hydrological stations in Guangdong province and reduce the production,living,and ecological environment problems caused by floods,the annual maximum flood flow series from 1977 to 2014 at seven hydrological stations in Guangdong province,namely,Sanshui Station,Makou Station,Gaoyao Station,Shijiao Station,Boluo Station,Huazhou Station,and Chaoan Station,are studied.MK test and Pettitt test are used to carry out study or wavelet analysis on the characteristics of the trend,variability,and cycle changes of the annual maximum flood flow at typical stations in the main streams of Guangdong province.The results show that:① the annual maximum flood flow at Boluo Station and Chaoan Station decreases slightly,while that at the other five stations increases,with that at Shijiao Station and Sanshui Station rising significantly.② Four of the seven stations have variability,and they are Gaoyao Station (in 1991 and 1992),Shijiao Station (in 1992,2011,and 2012),Makou Station (in 1993),and Sanshui Station (in 1993),and the variability occurs more than once at Gaoyao and Shijiao stations.In terms of spatial and temporal distribution,the four stations with variability mostly belong to the Xijiang and Beijiang river systems in the 1980s,1990s,and the 21st century.③ Sanshui Station has two main cycles of 2~10 a and 20~30 a,and Makou Station has cycles of 2~9 a and 9~27 a.Gaoyao Station experiences a cycle of 4~10 a and 10~24 a,and Shijiao Station owns a cycle of 2~12 a and 12~20 a.Boluo Station has a cycle of 5~12 a and 12~24 a.In addition,Huazhou Station experiences three cycles of 3~7 a,7~18 a,and 18~26 a,and Chaoan Station experiences cycles of 3~10 a,10~14 a,and 14~23 a,respectively.

Sergey A. Lavrov

It is impossible to explain impact of climate change on the surface and underground runoff of the permafrost zone without studying the seasonal processes of thawing of permafrost soils. These processes directly affect infiltration, evaporation and other hydro/physical characteristics, that is, they almost completely determine the mechanisms of runoff formation and its climatic interdependence.

Lesheng An, Kaihua Liao, Lei Zhu et al.

Dieudonn�Kaoga Kidmo, Bachirou Bogno, Kodji Deli et al.

AN Bei, JIANG Yanan, ZENG Qifei

Aiming at the “stepped” landslide displacement in the Three Gorges area,this paper proposes a new landslide displacement time series prediction model,namely VMD-SES-BP prediction model by combining variational mode decomposition (VMD),second exponential smoothing (SES),and BP neural network (BPNN);conducts the VMD of the GPS monitoring displacement data of landslide at Baishuihe River of the Three Gorges through this model to obtain the trend component and other sub-sequence components;makes rolling predictions of trend components by the SES,determines the influencing factors of other displacement components of the landslide through gray relational analysis (GRA),and learns and predicts by considering it as the training sample of BPNN.Comparing the prediction results of each component with the true value,the average relative error of prediction is 0.78%,the mean square error is 3.14 cm,and the correlation coefficient is 0.986.The experimental results show that the model is well applicable to the prediction of “stepped” landslide displacement,with high prediction accuracy,which provides a certain reference value for landslide displacement prediction.

LI Huadong, ZENG Jiali, PAN Yifei et al.

Under the disturbance of global warming and intensive human activities,runoff and sediment in the river basin have changed significantly,thus causing enormous ecological and environmental pressure in rivers,estuaries and coastal waters.Taking East River basin as the research object,this paper analyzes the temporal characteristics of runoff and sediment by M-K test and Pettitt test,quantitatively separates the impact of climate change and human activities on runoff and sediment in the river basin by the double mass curve method and modified SWAT model,and evaluates its effect on erosion and siltation of downstream river channel.Results show that:①SWAT model was suitable for the daily and monthly runoff and sediment simulations in the East River basin,with poor simulation for runoff and sediment with daily average discharges higher than 1 500 m³/s;②The change point of runoff and sediment was 1973 and 1988 respectively.Therefore,the baseline period for runoff was 1967—1973 and sediment was 1967—1988,while impact period was 2009—2016;③The impact of human activities on water and sediment changes in the basin is significant.Contribution of climate change and human activities for runoff in 2009—2016 was about 57% and 43% respectively.Climate change and population growth were the main contribution factors for annual runoff reduction.While human activities,especially dam construction,contributed over 90% of sediment.Population growth,soil and water conservation project,and dam construction in basin were the major factors for annual sediment reduction;④Affected by sand mining in river channel,after the baseline period,the impact of human activities,especially dam construction on the middle and lower channel was firstly decreased and then increased.During the impact period,the contribution of dam construction to the erosion and siltation of middle and lower river channel was 25.8%,which was not the main factor for the evolution of the middle and lower river channel.

Bouamer Kheira, Remini Boualem, Habi Mohamed et al.

With a flow estimated at 1200 m3∙s−1 and a height of 8 m downstream, the flood that occurred on October 10, 2008 spread along the M’zab River over a length of more than 180 km. Material and human damage is visible, but its effects on the quality of the waters of the alluvial layer remain unknown: this is the purpose of this paper. Samples of groundwater were taken during the period 2005–2012 in 4 oases of the valley. Physicochemical analyses were performed using molecular and flame spectroscopic methods and also volumetric methods on water samples. The results obtained were interpreted using histograms and hydrochemical diagrams, such as the Avignon software (L.H.A) (version 4, 2008). Low effect of flood on the water quality of the alluvial aquifer was manifested by concentrations of magnesium sulphate and calcium chloride. On the other hand, there is an accumulation of salts infiltrated by sewage except for the zone of Bouchen. The diagrams show that there is an improvement in water quality in this area.

Feizabadi Yaser, Gorji Effat Masomi

The aim of this study was to analyse the factors affecting agricultural water management in Iran based on irrigation experts’ point of view using factor analysis approach. The results indicated that conservation of modern irrigation equipment, promoting farmers’ knowledge, creating a watercourse (surface water collection), imposing a ban on digging new wells and educating the effectiveness of pressurized irrigation system were all known as the most important factors affecting agricultural water management. Moreover, factor analysis results showed that five factors influencing agricultural water management (institutional and legislative, educational and promotional, economic, technical and farming system) explained 64.29% of the total variance. At the end, some policy suggestions were provided in order to improve agricultural water management in Iran.

Marko Keskinen, Paradis Someth, Aura Salmivaara et al.

The water-energy-food nexus is promoted as a new approach for research and policy-making. But what does the nexus mean in practice and what kinds of benefits does it bring? In this article we share our experiences with using a nexus approach in Cambodia’s Tonle Sap Lake area. We conclude that water, energy and food security are very closely linked, both in the Tonle Sap and in the transboundary Mekong River Basin generally. The current drive for large-scale hydropower threatens water and food security at both local and national scales. Hence, the nexus provides a relevant starting point for promoting sustainable development in the Mekong. We also identify and discuss two parallel dimensions for the nexus, with one focusing on research and analysis and the other on integrated planning and cross-sectoral collaboration. In our study, the nexus approach was particularly useful in facilitating collaboration and stakeholder engagement. This was because the nexus approach clearly defines the main themes included in the process, and at the same time widens the discussion from mere water resource management into the broader aspects of water, energy and food security.

Hélida Karla Philippini da Silva, Vicente Natanael L. Silva, Marcílio Monteiro da Silva

A atual seca que passa o semi-árido do nordeste do Brasil é catastrófica, a escassez de recursos hídricos superficiais é critica, e os subterrâneos existentes apresentam muitas vezes teores de sais elevados, sendo inadequados para o consumo humano. O presente trabalho tem por objetivo expor a ação e a importância do projeto de recuperação, instalação e manutenção de sistemas de dessalinização de águas subterrâneas, através do processo de osmose reversa, realizado pela Associação Instituto de Tecnologia de Pernambuco – ITEP/OS em convênio com a Secretaria de Recursos Hídricos do governo do Estado de Pernambuco, que vem se apresentando como uma medida de adaptação e minimização dos efeitos adversos do fenômeno da seca em municípios do semi-árido do Estado de Pernambuco, adotando ainda, uma metodologia para o aproveitamento sustentável dos rejeitos gerados em tal processo, no intuito de não causar impactos negativos no meio ambiente.

Diogo Coelho Crispim, José Vicente Granato Araújo, Nilson Clementino Ferreira

As atividades antrópicas e a crescente expansão urbana têm provocado um profundo desgaste das águas superficiais e a busca de fontes alternativas de recursos hídricos. Observa-se desta forma a crescente preocupação da sociedade com a degradação das águas subterrâneas. A crescente utilização das águas subterrâneas para abastecimento público e para outras atividades produtivas tem forçado os gestores a desenvolverem programas de preservação mais efetivos, bem como ações de remediação. Devido aos elevados custos envolvidos em ambas as atividades, a remediação se torna prioritária. A definição da vulnerabilidade das águas subterrâneas à contaminação considera o conjunto de características físicas, químicas e biológicas da zona não saturada e/ou da áreas confinantes que, juntas, controlam a chegada do contaminante ao aquífero. O município de Senador Canedo é a unidade de controle utilizada no estudo. Consiste em um município pertencente à região metropolitana de Goiânia, capital do estado de Goiás, sendo considerado um grande polo de armazenamento petroquímico do Centro-Oeste do Brasil. O mapa de vulnerabilidade proposto possibilita a exploração consciente e preservação do aquífero, verificando a existência de áreas de baixa e insignificante vulnerabilidade no município, as quais favorecem a ocupação sem afetar a qualidade da água subterrânea, mas também orienta a ocupação por possuir extensas áreas de vulnerabilidade média, aproximadamente 63%.

Letícia Cordeiro, Alexandre de Oliveira Tavela, Nei Kavaguichi Leite et al.

Diversos agentes patogênicos podem ser veiculados pela água, sendo que o risco de contaminação aumenta dependendo da forma de consumo e o grau de proteção dos mananciais. Os fatores de risco associados ao potencial de transmissão de tais agentes são desconhecidos quando são consideradas fontes subterrâneas de abastecimento. O objetivo deste trabalho foi avaliar a qualidade das águas subterrâneas da região do rio Marombas quanto à presença de contaminantes de origem parasitária. Foram estabelecidos 17 poços tubulares e subterrâneos localizados em comunidades rurais dos municípios de Curitibanos, Brunópolis, Ponte Alta do Norte e São Cristóvão do Sul. Cada ponto foi avaliado mensalmente durante sete meses, sendo feita a identificação e quantificação de formas pré-parasitárias existentes. Observamos contaminação em todos os meses em pelo menos quatro dos poços avaliados. Os contaminantes mais comuns foram oocistos de Cryptosporidium sp. e cistos de Giardia sp. e Entamoeba sp. A partir dos resultados obtidos conclui-se que existe o risco de infecção por agentes parasitários de veiculação hídrica nas comunidades estudadas. Sendo assim, devem-se tomar medidas de conservação e manejo nas fontes naturais para minimizar fatores de risco para a saúde dos consumidores de água oriunda de poços tubulares na bacia do rio Marombas.

Xiao-qin Zhang, Wei-min Bao

Flow in tidal rivers periodically propagates upstream or downstream under tidal influence. Hydrodynamic models based on the Saint-Venant equations (the SVN model) are extensively used to model tidal rivers. A force-corrected term expressed as the combination of flow velocity and the change rate of the tidal level was developed to represent tidal effects in the SVN model. A momentum equation incorporating with the corrected term was derived based on Newton's second law. By combing the modified momentum equation with the continuity equation, an improved SVN model for tidal rivers (the ISVN model) was constructed. The simulation of a tidal reach of the Qiantang River shows that the ISVN model performs better than the SVN model. It indicates that the corrected force derived for tidal effects is reasonable; the ISVN model provides an appropriate enhancement of the SVN model for flow simulation of tidal rivers.

ZHONG Yong, YANG Fan, JIANG Shao-ying