• 全国中文核心期刊
  • 中国科技核心期刊
  • 美国工程索引(EI)收录期刊

2020 Vol. 31, No. 1

Display Method:
Conceptual hydrological model of corrosional hill karst watershed and its application
CHEN Xiaohong, YAN Yihan, LI Cheng, WEI Runchu
2020, 31(1): 1-9. doi: 10.14042/j.cnki.32.1309.2020.01.001
Abstract:
To mitigate the insufficiency of the traditional hydrological model in karst hydrological simulation, the Xin'anjiang Hydrological Model was modified by reconstructing a heterogeneous groundwater system with linear reservoirs and introducing the virtual area coefficient of the watershed (f) to modify non-conservative characteristics. The modified Karst Hydrological Model was applied to the Chongling River Basin, a typical corrosional hill region of southern Hunan Province, China. In addition, this study focused on dynamic changes of non-conservative characteristics based on the modified model. The results demonstrate the following:① The modified model outperformed the Xin'anjiang Model in karst hydrologic simulation (by 11.21%) especially in water balance (by 23.29%) and low water flow (by 27.64%); ② The non-conservative status of the karst watershed has duality because of the multi-directionality of the underground confluence system; ③ The area of the underground system is positively correlated with precipitation, while the variation of the area decreases with the increase of the precipitation by the constraint of underground saturation; ④ Inter-catchment water exchange exhibits time lag because of the hydration and water retention of karst.
Experimental study on discharge capacity of street inlet in urban flooding
CHEN Qian, XIA Junqiang, DONG Boliang
2020, 31(1): 10-17. doi: 10.14042/j.cnki.32.1309.2020.01.002
Abstract:
Urban flood disasters have occurred frequently in recent years in China, causing a serious threat to urban management and the safety of people and property. The discharge capacity of street inlet is very important to the drainage efficiency in flood-prone areas. Laboratory experiments on the discharge capacity of street inlet were conducted under various flow conditions based on a two-layer platform, covering the upper street layer, the triangular weir tank underneath, and a combination of grate inlet, catch basin and side tube between those two layers. The results show that:the grate inlet was operated like a weir when the catch basin was not full; while the combination was operated as a nozzle after it was full. Based on the experimental data, the discharge coefficients were calibrated for the types of weir and nozzle, respectively. Furthermore, an empirical formula for the discharge capacity of inlet was innovatively derived using the method of dimensional analysis, and the ratio of the composite velocity through inlet to the incoming velocity in front of grate inlet was expressed as a power function of the incoming Froude number. Finally, the proposed formula was validated in detail against existing experimental data for the real storm drain inlet, and it was found that under a higher incoming depth, the discharge capacity of inlet calculated by the proposed formula would be lower than the corresponding reference value adopted widely in practice. This study can provide quantitative basis for refined urban flood management.
Simulation of response law for control effect of runoff control at grass swale to key design parameters
HOU Jingming, LI Yuxi, TONG Yu, LIU Feifei, MA Liping, LIANG Hanghang
2020, 31(1): 18-28. doi: 10.14042/j.cnki.32.1309.2020.01.003
Abstract:
As one of the effective Low Impact Development measure, the grass swale has been widely used in road construction. In order to analyze the grass swale effects on the surface runoff control under different design parameters, a numerical model coupled hydrology and hydrodynamic processes is used. The reliability was verified against the measured runoff process. The simulation results show that grass swale plays an important role in reducing flood peak and delaying the peak time. The runoff control rates are more significant for grass swale with gentler transverse and vertical slops, and the overflow well located on the upper reaches of the flow inlet. Moreover, when the position of the overflow well varies, the runoff control rate and the flood peak reduction can be changed by 2% to 10% and 13% to 28%, respectively. If the transverse slope changes from 1/3 to 1/7, the runoff-control and flood-peak reduction rates can be increased by 4%-13% and 6%-23%, respectively. Besides, the runoff-control and flood-peak reduction rates are respectively improved by 7% to 16% and 12% to 29%, as the vertical slope changes from 0.5% to 0.3%. The conclusions obtained from numerical simulations provide design guidance of the grass swale and further widen the application.
Rapid simulation of urban rainstorm flood based on WCA2D and SWMM model
ZENG Zhaoyang, LAI Chengguang, WANG Zhaoli, WU Xushu, HUANG Guoru, HU Qingfang
2020, 31(1): 29-38. doi: 10.14042/j.cnki.32.1309.2020.01.004
Abstract:
This study attempts to combine the cellular automata inundation model (WCA2D) with SWMM (SWMM/WCA2D) to explore the mechanism and computational efficiency of WCA2D coupling the traditional one-dimensional pipeline network model. For this purpose, we developed a rapid flooding simulation technology with the Changban catchment (a typical catchment features complicated in Guangzhou) as a study case. By comparing with the measured inundation data and the simulation results performed by SWMM/LISFLOOD-FP model, we could obtain the following results:the simulation results are close to measured inundation data related to the "20180607" rainstorm, suggesting that the coupled model presents good precision. According to the results of model precision indices, the scenario considering the blockage of main pipe and buildings shows the highest simulation precision with the RTPR, RPPV and F1 of approximately 0.8, 0.6 and 0.7, respectively, which best characterizes the actual conditions of the study area. By coupling with SWMM, the simulation results of WCA2D and LISFLOOD-FP shows little difference (the maximum depth difference lower than 0.1 m) and higher correlation (the correlation coefficients almost larger than 0.7), however, the computational efficiency of WCA2D is 3-5 times higher than that of LISFLOOD-FP, indicating that the WCA2D could be feasibly and effectively combined by SWMM. Therefore, the coupled model (SWMM/WCA2D) proposed by this study could provide a novel way to implement rapid urban flooding simulation in the complicated urbanized areas.
Calculation of bend-scale sediment balance in meandering rivers of Yellow River source based on UAV aerial survey
LI Zhiwei, TANG Tao
2020, 31(1): 39-50. doi: 10.14042/j.cnki.32.1309.2020.01.005
Abstract:
Erosion-deposition changes of meandering channels are a dynamic equilibrium process in the long-term time scale. The part of sediment load transport is roughly equal the difference between bank erosion in concave bank and point bar deposition in convex bank. In summer 2018, the Unmanned Aerial Vehicle (UAV) aerial survey was used to obtain high-resolution imagery data in four meandering rivers of Yellow River source(i.e., Maiqu, Haqu, Gequ, and Lanmucuo Rivers), and the high-resolution topographic dataset were produced by post-processing of the Structure-for-Motion technology. Channel topography of cross sections of single bend and subsequent bends are extracted using ArcGIS. The differences of the cross-sectional area between convex and concave bank zone are calculated in single section and adjacent sections of meandering channels. Results demonstrate that sediment loss amount generated by bank collapse on concave bank and sediment deposition amount on convex bank are imbalanced, i.e., a net loss of sediment amount existing. For a single bend, the sediment loss per unit channel length in Lanmucuoqu River is about 0.191 m3, and about 0.045 m3 on average in Maiqu, Haqu, and Gequ Rivers. Nonetheless, the sediment loss in the reach scale of meandering channel is non-uniformity that indirectly reflects the difference in lateral migration rates among different bends.
SWMM-based rainfall-runoff simulations in large-scale urban area with no pipeline-flow observations: Ⅱ: model calibration and analysis of rainfall-runoff simulations
FU Xiaoran, WANG Dong, LUAN Qinghua, LIU Jiahong, WANG Haichao
2020, 31(1): 51-60. doi: 10.14042/j.cnki.32.1309.2020.01.006
Abstract:
At present, many cities in China are short of pipeline-flow observations, which leads to large challenges to construct urban hydrological models for detailed rainfall-runoff simulations. In this study, the core district of Yizhuang Economic Development Zone was selected as the study area. Based on the accurate digitalized land-surface data, field survey and empirical verification of urban storm process was carried out in terms of the maximum runoff depth at specific spots, and the SWMM model was calibrated and verified for the two typical storm events in July 21st, 2012 and June 23rd, 2011. Subsequently, the runoff response rate and traffic congestion risk of design rainstorms in different return periods were analyzed and evaluated in sub-catchments with various land-uses. The results show that as return period increases, street and transportation land-uses have a higher response rate to the increase of rainstorm than park and green land-uses do, and the former has a higher risk of waterlogging-triggered traffic congestion than the latter. This finding indirectly reflects the variability of runoff response rates under different land-surface conditions. This study is potential to provide decision-makers with valuable suggestions on effective local urban-flood control and early warning.
Numerical simulation of groundwater flow at cross-section scale in the lower reaches of Tarim River under the condition of ecological water conveyance
GULIMIRE Hanati, ZHANG Yin, GUAN Donghai, LIU Qianqian, SU Litan
2020, 31(1): 61-70. doi: 10.14042/j.cnki.32.1309.2020.01.007
Abstract:
Owing to limited surface water, groundwater is a critical water resource in the northwest China. Conversion process and its coupling simulation of surface water and groundwater are the foundation of water resources development, utilization, and scientific evaluation. In order to accurately reflect the dynamic changes of groundwater after ecological water conveyance, the groundwater level in Yingsu section of the lower reaches of the Tarim River was studied monthly for consecutive years. We proposed an improved groundwater dynamic (GH-D2) model based on Boussinesq equation to simulate the response of groundwater level fluctuation in the typical section of the green corridor to intermittent ecological water conveyance (2000-2015). The results show that although the GH solution of Boussinesq equation can well simulate the transient change of groundwater level, it is not ideal in simulating the multiyear changes in intermittent water conveyance river. The improved GH-D2 model takes into account the delayed effect of intermittent ecological water conveyance on the change of groundwater level, and performs well in the simulation of long-term changes. Compared with GH and GH-D1 models, the groundwater level simulated by GH-D2 model is more approaching to the observed value. This study will provide crucial technical support for the implementation of a scientific and rational ecological water conveyance project and for the ecological restoration and reconstruction strategy in the lower reaches of Tarim River.
Experimental study on the hydraulic characteristics of the two-stage energy dissipation in low Froude Number flow
TAN Gaowen, HAN Changhai, HAN Kang, YU Kaiwen
2020, 31(1): 71-80. doi: 10.14042/j.cnki.32.1309.2020.01.008
Abstract:
In this study, the problem of energy dissipation under low Froude number flow conditions is investigated based on the shape of a single stage stilling basin vs. a two-stage stilling basin. Tests on a physical model were conducted to study the hydraulic and energy dissipation structure characteristics of these two types of basins in low Froude number flow. The results of these experiments reveal that under low Froude number flow conditions, the large fluctuation area of the original single stilling basin is changed in the two-stage stilling basin into an adaptive area, while the adaptive area of the downstream tail water level increases significantly, and the fluctuation of the outlet water level decreases. In addition, the streamline in the single stilling pool is sparser and the velocity gradient and vorticity smaller than those of the two-stage stilling basin, while the Reynolds stress is significantly larger. The flow in the two-stage stilling basin is more stable, and the Reynolds stress zoning is more obvious than that in the single stage stilling basin. The surface rolling zone is markedly larger than the bottom rolling zone as well. Compared with the single stage stilling basin, the energy dissipation rate of the two-stage stilling basin is significantly improved, which is beneficial to the anti-scour protection of downstream riverbeds and the shore.
Impact of recent uneven channel evolution on hydrodynamic characteristics during flood season in the Pearl River Delta
CHEN Xiaoqi, YU Minghui, LIU Changjie, TIAN Haoyong, LIU Huamei
2020, 31(1): 81-90. doi: 10.14042/j.cnki.32.1309.2020.01.009
Abstract:
To explore the relationship between changes of riverbed topography and adjustments of flood dynamic characteristics of the Pearl River Delta (PRD) in 1999-2008, a one-dimensional river network mathematical model was established based on the surveyed topography in 1999. The "08·6" flood was first reproduced and model-data comparison was implemented; then, the impact of topography change of river network on hydrodynamic characteristics during flood season in the PRD was investigated. Results show that the flood diversion capacity of channels is increased due to the down-cutting of riverbed in the PRD. During the flood "08·6" (a recurrence period of 30 years), the water surface elevations are generally lower than before, with a maximum decrease about 0.9 m at the Makou station. The tidal range and tidal velocity are found to increase, making the tidal limit move to above Makou and Sanshui stations. The riverbed down-cutting in the Xijiang river networks is larger than that in the Beijiang river networks. Uneven riverbed down-cutting leads to changes of discharge ratio in river network nodes, during the flood season, flood diversion of the Xijiang river networks increases by 2%, and the peak discharge of the Makou and Tianhe stations increass by about 1 500 m3/s and 1 000 m3/s, respectively. The trend that the diversion ratio at Makou station decreases with the increase of upstream flood discharge does not change. Nevertheless, the uneven-riverbed-down-cutting caused diversion ratio changes increase. The riverbed uneven down-cutting in recent years is the major reason for the reduction of flood risk of the river networks in the PRD, especially in the central region of the PRD.
Numerical simulation of water-gas two-phase movement mechanism of bubbling phenomenon in front of dam
ZHAO Lanhao, GUAN Ce, ZHANG Hairong, LI Tongchun
2020, 31(1): 91-101. doi: 10.14042/j.cnki.32.1309.2020.01.010
Abstract:
A coupled Level-Set method for the analysis of free surface seepage is established, which is meant to analyze the cause of bubbling phenomenon after the water level rose rapidly in Huangbizhuang Reservoir, and to ensure the reservoir is in safe operation. The gas phase compressibility during the infiltration process is considered, thus the movement and fusion of the water-gas two-phase interface in porous medium can be reflected intuitively during the infiltration process. This method can solve the seepage problem involving gas phase which cannot be solved by conventional methods. The two-phase movement processes in front of dam of Huangbizhuang Reservoir in different water storage processes were simulated with this method. The results showed that:the bubbling phenomenon of water surface in front of dam was caused by the sudden rise of the water level, which surrounded air in the blanket and compressed air with the water infiltration process, until the air pressure reached the break pressure, then air released; the key factor affecting the occurrence and development of the bubbling phenomenon is the water storage process. The simulation results are basically consistent with the actual observation results, which verifies the rationality of the method.
Influence factors of hydraulic parameters of roll waves in overland flow
MENG He, ZHANG Kuandi, WANG Jingwen
2020, 31(1): 102-111. doi: 10.14042/j.cnki.32.1309.2020.01.011
Abstract:
In ascertain the evolution process and generating mechanism of roll waves, the variation rules of hydraulic parameters of roll waves under five kinds of roughness, five different energy slopes and eight unit discharges was studied by using a fixed bed test and ultrasonic measurement technology. The results showed that at the fixed section, the wave velocity increased as a power function with increasing unit discharges, while the relative wave velocity exhibited an opposite trend. The wave height and relative wave height first increased and then decreased as unit discharges increased. With the increase of roughness, wave velocity decreased while relative wave velocity increased. However, the wave height and relative wave height both decreased with an increasing roughness. The influence of energy slope on roll waves was also related to roughness. Under a small roughness, the wave velocity increased as a power function with the increasing energy slope while the decreasing power function between relative wave velocity and energy slope was found. Wave height first increased and then decreased while the relative wave height increased continuously. However, under a large roughness, the relative wave velocity increased and the wave height remained stable during the whole process with an increasing energy slope. In contrast, although the relative wave height increased first but this trend became less obvious and the height even decreased as energy slopes increased. Therefore, taking into account the influence of average hydraulic parameters were taken into account when adopting the relative wave velocity and relative wave height, which could better reflect how various factors affected the evolution process of roll waves.
Flow structure characteristics and changes in a simulated riverbank nest-shaped flow slide
ZHANG Xingnong, NIU Chenxi, JIA Dongdong, YING Qiang
2020, 31(1): 112-119. doi: 10.14042/j.cnki.32.1309.2020.01.012
Abstract:
A generalized Lab-test in a flume was performed to simulate a typical riverbank collapse called a nest-shaped flow slide in the middle-lower reaches of the Yangtze River. To explore failure mechanical mechanisms, the characteristics and variation in water flow structure near the caving pond during the collapse formation and development were studied using by fine survey data of the flow field. Results show that the flow around the pond can be divided into three zones:the main flow, the eddy flow and the circumfluence zones, where the flow structure changed continuously with the collapse development. In the main flow zone outside the pond mouth there is basically an open bend channel current with obvious circulation characteristics. In the eddy flow zone appearing a strip-shape there are many vortices varying in size, shape, position and strength that generally move down with the main flow rapidly, and breaks down or decomposes continuously. At the upper and lower ends of the pond mouth, the current clearly exhibits the three-dimensional characteristics, with strong and violent water surface fluctuation. In the circumfluence zone there is a typical cavity flow, and as the collapse develops, the circumfluence expands, its center moves down, its shape changes from elliptical to circular, and its strength shows an increase-decrease-stabilization trance.
The limit of water temperature influence of cascade reservoir
ZHAO Gaolei, LIN Ling, PU Xunchi, LIANG Ruifeng, LI Kefeng
2020, 31(1): 120-128. doi: 10.14042/j.cnki.32.1309.2020.01.013
Abstract:
The construction of reservoirs has a certain impact on the environment while bringing great economic benefits to flood control, power generation, irrigation and water supply. In particular, the water temperature of the downstream river is changed by the discharge of reservoirs, which disturbs the natural rhythm of swimming, plant reproduction and growth, while the cascade reservoir undoubtedly magnified this effect. In order to study the limited effect of reservoir cascade construction on water temperature, the virtual reservoir Alpha was constructed, and the Alpha reservoir was connected infinitely with the first and last ends, and then the water temperature of the cascade reservoir was simulated by the two-dimensional mathematical model CE-QUAL-W2 with the average width. The results show that the cumulative impact of water temperature brought by the cascade development of river is limited, and the cascade temperature has greatly weakened the water temperature stratification phenomenon, but the hierarchical structure of the reservoir will not disappear; after the adjustment of 22 cascades, the discharge temperature of the reservoir does not change relative to the temperature of incoming water, both the water temperature on the surface and bottom of the reservoir are the same as those of the upstream cascade, and the flow field of the reservoir area is also the same as the upstream flow field; when the cumulative impact of water temperature in the reservoir reaches the limit, it indicates that the heat of the inflow and outflow reaches the equilibrium completely.
Advances of precipitation nowcasting and its application in hydrological forecasting
LIU Jia, QIU Qingtai, LI Chuanzhe, JIAO Yufei, WANG Wei, YU Fuliang
2020, 31(1): 129-142. doi: 10.14042/j.cnki.32.1309.2020.01.014
Abstract:
With the global climate change and the imbalance of the ecological environment, extreme weather frequently occurs and presents multi-scale temporal and spatial variability characteristics. Early forecasting and warning of the extreme weathers has always been the focus of attention in the hydrometeorological field. Nowcasting can accurately predict the significant short-term changes of the future weather, and has become the main means of forecasting extreme weathers such as heavy precipitation events. In this study, a detailed overview of precipitation nowcasting is firstly given based on the developments of the 0-3 h weather radar extrapolation nowcasting and the 0-6 h blending nowcasting of weather radar and numerical weather prediction models. Special attentions are paid in briefing the developments of the radar extrapolation algorithms, and the blending techniques of weather radar and numerical weather prediction models. It is pointed out that there is great potential for the 0-6 h blending nowcasting in improving the accuracy of precipitation nowcasting and extending the forecast lead time, and to explore more advanced blending techniques is the core of the future development of nowcasting. At present, the application of precipitation nowcasting through atmospheric-hydrologic coupling is the main way to help improve the accuracy and guarantee the reliability of hydrological forecasting. Based on the discussion of the key issues in atmospheric-hydrologic coupling studies, e.g., the popular coupling mode, the matching problem of the spatial scale, and the uncertainties of hydrological models, the developments of studies incorporating radar extrapolation nowcasting and blending nowcasting into hydrological forecasting are presented, and the advantage of blending nowcasts in extending forecast lead time and improving forecast accuracy is illustrated. Finally, the research focus and future development is pointed out for blending nowcasting and its application in hydrological forecasting.
Status and development trend of research on risk consequences caused by dam breach
GE Wei, JIAO Yutie, LI Zongkun, ZHANG Zhaosheng, GUO Xinyan
2020, 31(1): 143-151. doi: 10.14042/j.cnki.32.1309.2020.01.015
Abstract:
Risk consequences analysis of dam breach is fundamental to risk assessment of reservoir dams. Multiple influencing factors and complex mechanisms lead to great differences between the analysis results of different research methods and the actual consequences. It is suggested that risk consequences can be divided into three basic categories:loss of life, economic loss and environmental impact, based on their definitions. According to the analysis of research achievements and applications abroad, the development trend that physical model based on disaster-causing mechanism takes place of empirical model based on historical data is clarified. Based on the analysis of research status of dam breach risk consequences assessment in China, both advantages and disadvantages of three main research methods, i.e. analysis based on empirical model and disaster-causing mechanism, semi-quantitative evaluation and superposition calculation of regional losses, are clarified in terms of accuracy and practicability. It is proposed that the risk consequences research and practical application can be improved in four aspects, i.e., strengthening the analysis of disaster-causing mechanism, paying attention to the combination of accuracy and practicability, emphasizing the important roles of non-engineering measures and improving the research constantly during application.