• 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

2021 Vol. 32, No. 3

Display Method:
Risk propagation from meteorological to hydrological droughts in a changing climate for main catchments in China
GU Lei, CHEN Jie, YIN Jiabo, GUO Qiang, WANG Huimin, ZHOU Jianzhong
2021, 32(3): 321-333. doi: 10.14042/j.cnki.32.1309.2021.03.001
Abstract:
Global climate change has altered the spatial-temporal regimes of hydro-meteorological variables. The impact of climate change on the risk transferability from meteorological to hydrological droughts needs to be investigated. Based on the gridded meteorological data and 19 global climate model simulations from the Coupled Model Inter-comparison Project Phase 5, the climate change scenarios were generated over 135 catchments in China for two future periods (2011—2055 and 2056—2100). The best performed hydrological model over four lumped models was selected for hydrological simulations. Based on precipitation scenarios and hydrological simulations, the Standard Precipitation Index (SPI) and the Standard Runoff Index (SRI) were respectively calculated for each catchment and time period. The meteorological and hydrological drought episodes were extracted based on the runoff theory. Finally, drought risks by incorporating the most likely selection into the Copula function were calculated, and the risk transferability from meteorological to hydrological droughts under the current and future climates were investigated. The results show that: ① Meteorological and hydrological droughts are highly sensitive to future warming climates. Specifically, drought return periods are projected to lengthen in northern China, indicating mitigating risks, while they become shortened by 2 to 5 times over most catchments in central and southern China, indicating deteriorated conditions. ② The meteorological drought risks positively correlate with the hydrological drought risks under the current and future climates, with the Pearson correlation coefficients being higher than 0.99. ③ The sensitivity of hydrological to meteorological drought risks almost stay unchanged for each catchments for different future periods, whereas the co-occurrence of hydrological and meteorological droughts is projected to slightly increase over northern China under future warming climates.
Construction and evaluation of an integrated hydrological and hydrodynamics urban flood model
HUANG Guoru, CHEN Wenjie, YU Haijun
2021, 32(3): 334-344. doi: 10.14042/j.cnki.32.1309.2021.03.002
Abstract:
To reduce the losses induced by urban flood hazards, it is necessary to research urban flooding via numerical modeling and to obtain accurate and reliable flood information in advance. According to the hydrological and hydrodynamic theories and methods in urban flood research, a specific method for the coupling of one-and two-dimensional models is proposed in the present work. An integrated hydrological and hydrodynamic model is constructed via horizontal and vertical connections based on the Storm Water Management Model (SWMM) and a self-developed two-dimensional model. This research also proposes a novel coupling strategy for one-and two-dimensional models based on a dynamic-link library. The coupled model is verified by both theoretical and practical case studies. Taking the vertical connection problem as the theoretical case study, the correctness of the model was proven by comparing the model results with InfoWorks ICM software. To verify the flood modeling capacity of the model in watershed-scale areas, the Donghaochong Basin in Guangzhou was taken as another case study. The modeled results were found to be in line with the measured data under two historical rainfalls, which indicates that the model exhibited good precision and reliability in both pipe flow and surface flow simulations. In summary, the proposed coupling method is both reasonable and feasible, and the integrated hydrological and hydrodynamic model is reliable and of significant application value.
Driving mechanisms of urban floods under the changing environment: case study in the Wenyu River basin
REN Meifang, XU Zongxue, PANG Bo
2021, 32(3): 345-355. doi: 10.14042/j.cnki.32.1309.2021.03.003
Abstract:
Climate change and urbanization are regarded as the major driving factors for floods in urban watersheds. Many studies have witnessed the impact of climate change and urbanization on streamflow in different regions are different. Identification of driving factors for floods and quantifying the impact of climate change and urbanization on urban flood variation are important significance for floods management in urban watersheds. The Wenyu River basin in Beijing, which has undergone a highly urbanized process, is selected as the study area in this study. The GAMLSS model was developed for different probability of discharges in summer, with seasonal precipitation, air temperature, antecedent wetness, impervious areas and groundwater level as covariates, to study the mechanism of discharge variation in urban watershed. Results showed that all of the different probability of discharges in summer showed the nonstationary characteristics; increasing impervious areas and precipitation are major driving factors for floods in the Wenyu River basin. Different probability of discharge has different driving mechanism, smaller discharges with probability higher than 70% was mainly affected by changes of land use on ground surface, while the greater one, especially the extreme floods below 45% probability were mainly influenced by precipitation.
Quantifying attribution of the river hydrological health variation based on ecological-flow threshold method
JIANG Shanhu, ZHOU Le, REN Liliang, WANG Menghao, WEI Linyong, YUAN Fei
2021, 32(3): 356-365. doi: 10.14042/j.cnki.32.1309.2021.03.004
Abstract:
Environmental change has altered the river hydrological health regimes, and consequently affected the ecological health of river. Therefore, it is essential to develop a method to quantitatively analyze the attribution of river hydrological health evolution. This study selected the typical semi-arid Laohahe River basin in Northern China as a case study area. Observation data were obtained from 3 hydrological stations, 17 rain gauge station and 6 meteorological stations in the study area. Firstly, the natural streamflow series from 1964 to 2016 was reconstructed using the observations and the Variable Infiltration Capacity (VIC) model. After that, the level of river hydrological health (H) was assessed based on the ecological flow threshold, which was calculated by probability density curve. Finally, the 'simulated-observed' comparison method was adapted to quantify the effect of climate changes and human activities on the river hydrological health. Results showed that human activities were the major factors that have caused river hydrological health deterioration since 1980 in Dianzi and Taipingzhuang sub-basins, which accounted for 86.9% and 87.9%, respectively. Widespread agricultural irrigation and reservoir operation were the two crucial reasons that caused the alterations of natural hydrological regime, which further led to the river ecological destruction over Laohahe River basin. Whereas, increasing rainfall in 1990s had a significant effect on maintaining river hydrological health because the large amount of rainfall helped reduce the human activities influence. The case study demonstrates that the attribution of river hydrological health evolution can be quantitatively described based on ecological-flow threshold and 'simulated-observed' comparison method, which will provide scientific basis for river ecology protection and water resource management under changing environment.
Exploring evapotranspiration characteristics in urbanized areas of Tianjin plain
CAO Runxiang, LI Fawen, LI Jianzhu, FENG Ping
2021, 32(3): 366-375. doi: 10.14042/j.cnki.32.1309.2021.03.005
Abstract:
To reveal the characteristics of urban-based evapotranspiration, a SEBS-Urban model was applied to estimate the monthly evapotranspiration(ET) that occurred in the plain area of Tianjin over 2015—2017 considering anthropogenic heat release. A two-step verification method was used. First, a comparative analysis was performed with the MODIS MOD16 products for rural areas. Second, the urban water dissipation (UWD) framework was used to assess the model's performance in built-up areas. The feasibility of the Budyko formula was explored based on the SEBS-Urban results. Three key results were obtained: ① The SEBS-Urban model is reliable, and the results of the built-up area ET analysis are consistent from the perspectives of an urban surface energy balance and a dualistic water cycle. ② The ET increment ranges up to 85%~115% for the built-up area but only 7.2%~8.7% for the whole study area after including considerations for anthropogenic heat. ③ The Budyko formula obtained good results for estimating evapotranspiration in the study area, suggesting that it can also be applied to urban areas. The results of this study can provide a necessary reference for studies on evapotranspiration in urbanized areas.
Multi-objective time-varying preference decision-making method for basin water resource dispatch and its application
DONG Zengchuan, NI Xiaokuan, CHEN Mufeng, YAO Hongyi
2021, 32(3): 376-386. doi: 10.14042/j.cnki.32.1309.2021.03.006
Abstract:
In view of the dynamic change of competition relationship and its intensity among multiple objectives in different periods of basin water resources system scheduling process, a multi-objective time-varying-preference decision-making method is proposed. Taking the lower reaches of Jinshajiang River as an example, the spatiotemporal variabilities of power generation and ecological objectives are analyzed, and the Pareto frontier cluster of these two targets in chronological order is constructed and calculated. In addition, based on the non-dominated relationship of sensitivity ratio between targets, the objective preference of decision makers in each scheduling period is identified quantitatively to form the decision support set of bias degree, and a multi-objective time-varying decision-making model is established. The results show that there is a significant competitive relationship between cascade power generation and ecological objectives in the lower reaches of Jinshajiang River in normal flow year. The competition is the strongest in the refill period and weakest in the flood season; the competition intensity strengthens with the increase of power generation in each period. The time-varying-preference decision-making method, based on the physical basis of dynamic Pareto front, can significantly optimize the ecological benefits while maintaining the power generation benefits, and improve the guarantee degree of ecological demand in the critical period.
Water resources spatial equilibrium evaluation method based on connection number and Lorenz curve
JIN Juliang, XU Xinguang, CUI Yi, ZHOU Rongxing, WU Chengguo, ZHANG Libing
2021, 32(3): 387-395. doi: 10.14042/j.cnki.32.1309.2021.03.007
Abstract:
In this study, an evaluation approach based on the connection number and Lorenz curve was proposed to investigate the quantitative impact of each sub-region on the spatial equilibrium of the water resources in the entire region during the evaluation process. The Lorentz curves connecting the total amount of water resources with cultivated land area, population and the secondary industry GDP were constructed, respectively, where the evaluation sample value based on the vertical distance was calculated. Meanwhile, the connection number of the sample was calculated via the set pair analysis, followed by the determination of equilibrium level and the comparison with the Gini coefficient method. Application of the proposed approach to Anhui Province of 2011—2018 revealed that the overall spatial imbalance status existed between the total amount of water resources and cultivated land area, population size along with the secondary industry GDP, respectively. In contrast, the level of equilibrium between the total amount of water resource and cultivated land area, population size has been ameliorated, while the equilibrium status of the total amount of water resource and the GDP of secondary industry remained serious that require further improvement. With the quantitative estimations, it offers a novel and effective way for estimating the spatial equilibrium of regional water resources.
Temporal variation characteristics and attribution analysis of terrestrial water storage change in the Yangtze River basin
NIE Ning, ZHANG Wanchang, CHEN Hao, ZHAO Dengzhong, LIU Min
2021, 32(3): 396-407. doi: 10.14042/j.cnki.32.1309.2021.03.008
Abstract:
We explored the temporal variation and attribution characteristics of terrestrial water storage change (TWSC) in the Yangtze River basin by using Gravity Recovery and Climate Experiment (GRACE) satellite observations and hydrological model simulations and reconstructing and analysing the monthly TWSC over the Yangtze River basin during 1988—2012. Based on the simulation results of 13 scenarios, we quantitatively separated the relative contributions of climate variability and crucial human activities (including land use changes and reservoir operations) to TWSC. The main results were as follows: ① The basin-level averaged TWSC, precipitation, evapotranspiration, and runoff depth showed changing trends at linear rates of 0.1, -3.5, 0.6, and-4.2 mm/a, respectively. ② The monthly non-seasonal TWSC was significantly and negatively correlated with the Southern Oscillation Index, with a significance level of α < 0.01. ③ Climate variability played a leading role in the TWSC variations, and the contribution rates of reservoir operations to the monthly mean TWSC were negatively correlated with those of climate variability, and lastly. ④ Following the construction of the Three Gorges Reservoir, the influence of reservoir regulation on the monthly mean TWSC was significantly enhanced; it presented seasonal variations in which TWSC was reduced by reservoir operations during January—May and enhanced during July—December. This study developed a useful research framework for attribution analyses on TWSC, and the results can provide decision support for water resource planning and management in the Yangtze River basin.
Three-dimensional numerical of the asynchronous movement characteristics of flood and sediment peaks in the Three Gorges Reservoir
ZHANG Bangwen, WU Baosheng, ZHANG Ruoyin
2021, 32(3): 408-417. doi: 10.14042/j.cnki.32.1309.2021.03.009
Abstract:
After the impoundment of the Three Gorges Reservoir, the increase of water depth caused the increase of the lag time of the sediment peak behind the flood peak in the flood propagation. The asynchronous movement characteristics between the flood and sediment peaks can be utilized to conduct the sediment peak regulation, one of the crucial measures to reduce the reservoir sedimentation. The three-dimensional numerical model named SCHISH (Semi-implicit Cross-scale Hydroscience Integrated System Model) was adopted to study the asynchronous movement characteristics of the flood and sediment peaks in the Three Gorges Reservoir. The reliability and accuracy of the model were verified by comparing the water and sediment transport during the flood season in 2013, then the asynchronous movement characteristics of the flood and sediment peaks under different impounded levels were preliminarily analyzed based on the model results. The results showed that the numerical model could accurately simulate the long-distance propagation of the flood and sediment peaks. The impounded level in front of the dam had little influence on the propagation time of the flood peak, but had a significant effect on the propagation time of the sediment peak. The increase of the impounded level resulted in the decrease of the flow velocity and the sand-carrying capacity, so the propagation speed of the sediment peak was slower and the sediment peak value was smaller, which led to the longer lag time of the sediment peak behind the flood peak along the reservoir. The research results can provide scientific evidence for further optimization of the operation of the sediment peak regulation in the Three Gorges Reservoir.
An experimental model to study the factors affecting flow pressure in floods
XIAO Shiyun, GUO Xiaoyang, LI Na
2021, 32(3): 418-426. doi: 10.14042/j.cnki.32.1309.2021.03.010
Abstract:
Floods cause great harm to buildings in flood zones, and the study of flood loads forms the basis for studying the vulnerability of such buildings. Tests were conducted on a model to study the pressure distribution on a building surface in a flood zone for various heights of floodwater and flow velocities. For these tests, the height of the floodwater and flow velocity on the incident flow surface of the model were controlled with an adjustable outlet on a wave flow tank. The model was divided into two layers, with holes being placed in the lower layer, and was located downstream of the outlet to the water tank. The test results show that the flow velocity is non-uniform and that the pressure due to the flow decreases from the bottom to the top of the model. The experimental data shows that the hydrodynamic pressure increases with an increase in flow velocity in a nonlinear manner. Based on this relationship, a hydrodynamic pressure correction coefficient is proposed to improve the accuracy of the calculation of flow pressure. The relationship between water pressure and water height is approximately linear. The presence of holes in the lower layer and boundary reduces the flow velocity and pressure to some extent. The results of this study provide a basis for flood-resistant designs of buildings and the evaluation of the flood-resistant capacities of buildings in flood zones.
Impact of regulating rubber dams on the accompanied flood risk during
ZHANG Chen, YU Hao, YU Ruolan, ZHENG Yunhe, YANG Rui, GAO Xueping
2021, 32(3): 427-437. doi: 10.14042/j.cnki.32.1309.2021.03.011
Abstract:
Existing risk analysis methods have neither the simulation of physical processes nor the discussion of risk randomness. Taking the Interconnected River System Network (IRSN) as an example, the associated risk analysis model of IRSN under random hydrological conditions was established based on the hydraulic model and the correlation of flood peaks. The flooding process in the upper reaches of the Yi and Shu River System is simulated by 1 200 sets of hydrological conditions. Aiming at the problem of flood peak superposition caused by rubber dams, this paper provides risk control suggestions for rubber dam operation and dispatch under different flood return periods. Our results showed that the risk of water level is extremely high (risk probability> 0.8) and the risk of flow rate is lower than 0.3 at the site of the rubber dam under the conditions of the 50-year flood return period and the hundred-year flood return period. When the rubber dam is increased by about 25% of the designed dam height, the risk of water level increases by approximately 70% in front of the dam in the Yi and Shu Rivers, and the risk of flow rate is reduced by about 50% at the dam site of the Shu River. If the dam is collapsed to release water before the flood season, the superposition of man-made flood peaks will cause an extremely high risk in the middle and lower reaches of the Shu River. By dividing the comprehensive flood risk safety area of water level and flood rate, it is suggested that the rubber dams be adjusted to less than 50% of the designed dam height before flood season in the Yi and Shu Rivers, and the depth and velocity the of Shu River be controlled within 12 m and 2.23 m/s respectively, so as to reduce the risk of water level and flow rate to low risk (< 0.4) in the 50-year flood return period. Moreover, to effectively reduce flood control pressure of the Yi and Shu River System in a hundred-year flood return period, it is necessary to adjust the rubber dams to below 25% of the designed dam height or to slowly collapse the dam before the flood season.
Experimental study of the wave-induced current for emergent rigid vegetation under regular wave conditions
CHEN Jie, YAO Zhen, JIANG Changbo, ZENG Siyi, CHEN Kelun
2021, 32(3): 438-448. doi: 10.14042/j.cnki.32.1309.2021.03.012
Abstract:
To understand the variation of the wave-induced current for emergent rigid vegetation, a series of laboratory experiments were conducted in a wave flume with two water depths, a variety of regular wave conditions, and two emergent plants modes. Based on the hypothesis testing, the predicting models for the canopy-drag length and the characteristic vegetation parameters were established respectively. The results showed that the current is predominantly induced by the root when the stem density was 60 plants/m2. Based on this observation, a model for predicting the maximum temporal-averaged flow for emergent vegetation was proposed by the extension of the existing model derived from submerged vegetation. The stem can reduce the root-mean-square of the mean current, the relative reduction constant at and above the root was a parabolic function of Ursell number. In the distribution of cluster roots, the stem had a stabilizing influence on the vertical velocity structure, especially at the normalized vertical position corresponding to the maximum of the temporal-averaged flow velocity.
Experimental study on the property of bed load motion based on the underwater photography technology
LIU Mingxiao, Michele Guala, SUN Dongpo
2021, 32(3): 449-457. doi: 10.14042/j.cnki.32.1309.2021.03.013
Abstract:
In order to improve the observation accuracy and efficiency of bed load experiments, the fine experimental observations of the movement and the state transition of bed sands in open channel flow were accomplished by means of underwater photography and particle tracking (UP/PTV). The reliability of the sampling data was improved by removing the interference caused by bed sands wagging, and setting the critical threshold of particle motion state as well as adapting multiple filter screening programs. By conducting series of bed load experiments under low transport intensity conditions, data including motion trajectory, velocity and step duration of bed particle was obtained, which was analyzed using a Lagrange process and the Probability Density Function (PDF) of the particle motion elements. Experimental results indicated that, the particle velocity shows a trend that increases rapidly at first and then decays slowly during the process of one single step, which is caused by inter particle collision and sweep events of near-bed turbulence. The PDF curve of particle velocity presents the Gamma function distribution with a thin tail, while the PDF curve of particle acceleration shows the Laplace distribution characteristics, influenced by the particle wagging effect. The particle velocity is closely associated with the friction velocity u*, maintaining a ratio of 3.4 to 3.5. The joint distribution of the single step duration Ts and the single step length Ls of the particles presents an exponential function, and the exponent of the fitting curves ranges between 1.25 and 1.30. The exponent is associated with the transport intensity of bed load and the heterogeneity of the bed surface particles.
A review of hydrological regulation functions of watershed wetlands
WU Yanfeng, ZHANG Guangxin
2021, 32(3): 458-469. doi: 10.14042/j.cnki.32.1309.2021.03.014
Abstract:
Wetlands play an important role in watershed hydrological processes that underlie a range of potential ecosystem services. A solid understanding of watershed hydrological regulation functions provided by wetlands, i.e., supporting watershed water balance, attenuating flood and drought risks, and mitigating climate change, is extremely meaningful for reaching sustainable wetland and water resources management. This paper provides a thorough review of the hydrological regulation functions of watershed wetlands. It addresses the definition and connotation of hydrological regulation functions of watershed wetlands as well as their three principal characteristics, namely spatiotemporal variation, threshold effects, and multidimensional nature. The internal driving factors of the functions include soil properties, vegetation characteristics and initial hydrological conditions, and the external factors are watershed characteristics, rainfall patterns, climate change, and anthropogenic activities. The methodology and available hydrological models for quantifying hydrological regulation functions of watershed wetlands are systematically summarized and discussed. Finally, considering discipline development and manage requirements of ecohydrology theory, we highlight specific research gaps and barriers that need to be filled in hydrological regulation functions of watershed wetlands.
Advances in biogeomorphology of tidal flat-saltmarsh systems
ZHOU Zeng, CHEN Lei, LIN Weibo, LUO Feng, CHEN Xue, ZHANG Changkuan
2021, 32(3): 470-484. doi: 10.14042/j.cnki.32.1309.2021.03.015
Abstract:
As an important type of coastal wetlands, tidal flat-saltmarsh systems provide a variety of key ecosystem services for estuarine and coastal areas, and have important socio-economic and ecological values. The understanding of their geomorphological evolution is the basis of coastal zone restoration and scientific management. This review recalls previous studies on the evolution of tidal flat geomorphology. Research focused on tidal flat-saltmarsh systems has gradually changed from traditional geomorphology to biogeomorphology which involves disciplines such as hydrodynamics, geomorphology, sedimentology, ecology and biology. It is a typical interdisciplinary research field. The paper summarizes the interaction between saltmarshes and hydrodynamics, sediment transport, geomorphology, human activities, biological activities, and other relevant processes on tidal flat-saltmarsh systems. This study summarizes the current relevant models and understanding of the dominant mechanisms that play a role in the evolution of tidal flat-saltmarsh systems. Finally, some future research directions such as the description of biological activities and development of land-sea coupled biogeomorphological models are proposed.