• 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

2014 Vol. 25, No. 1

Display Method:
Seasonal precipitation forecasts over China through calibration and combination of multiple CGCMs
PENG Zhaoliang, Q. J. WANG, WANG Ziru, WANG Guoli, XU Chao
2014, 25(1): 1-9.
Abstract:
To alleviate systematic deficiencies of two latest seasonal forecast systems in forecasting seasonal precipitation over China, a slightly modified Bayesian joint probability (BJP) modelling approach was employed to calibrate the ensemble means of the raw forecasts firstly. The calibrated forecasts were then merged through Bayesian model averaging (BMA) to combine strengths from different models. The results suggested that the BJP calibration models effectively removed biases and improved both reliability and overall accuracy of the raw forecasts. The calibrated ECMWF System4 (SYS4) forecasts exhibited some skill over broad regions of China in most seasons, whereas the calibrated Australian Bureau of Meteorology’s POAMA2.4 (P2.4) forecasts only showed weak skill over some regions in some seasons. Forecast skill of the merged forecasts from both sets of calibration models was improved greatly. Comparing with the SYS4 and P2.4 calibration forecast, the proportion of grid cells with positive RMSEP skill score was improved by 13.3% and 20.0%, respectively.
Effects of climate change, land use and cover change and CO2 enrichment on runoff: A case study of the Luanhe River basin
ZENG Sidong, XIA Jun, DU Hong, ZHANG Liping, CHEN Xiangdong, WANG Renchao, ADITYA Sood
2014, 25(1): 10-20.
Abstract:
Investigating the effects of climate change, land use and cover change (LUCC) and increased CO2 concentration on catchment runoff is important for acquiring an understanding of ecohydrological processes under changing environment at a basin scale. To analyze these effects, a model is developed through coupling a hydrological model (Distributed Time Variant Gain Model; DTVGM), a global terrestrial biogeochemical model for carbon, nitrogen and phosphorus (CASACNP) and a land use Cellular Automata -Markov (CA-Markov) model. The coupled model is then applied to the Luanhe River basin of Northern China. The model performs well during both model calibration and validation processes. The calibrated model is then used to study the effects of climate change, LUCC and CO2 enrichment on runoff over the basin. Results show the effects of climate change and LUCC on runoff are stronger than that of increased CO2 concentration. The annual runoff exhibits a decreasing trend for the period 2020—2049, and shows a reduced runoff as compared to the base year for most of the scenarios. The intra-annual analysis shows a decrease in runoff during wetter months and an increase during drier months. The monthly runoff during flood seasons would be more sensitive in the future as compared to non-flooding seasons.
On hydrological response to land-use/cover change in Luanhe River basin
SHI Xiaoliang, YANG Zhiyong, YAN Denghua, LI Ying, YUAN Zhe
2014, 25(1): 21-27.
Abstract:
This paper, taking the Luanhe River basin as a research area, quantifies and evaluates the hydrological response to land-use/cover change. Using the distributed hydrological model Soil and Water Assessment Tool (SWAT) and the land-use data of 1985 and 2000, the responsive relationship between the surface runoff variation and the major types of landscapes is analyzed. The result shows that the calibrated SWAT model can well simulate the monthly flows, and is thus applicable to the study of Luanhe river basin. From 1985 through 2000, the conversion from forestry land to farmland and grassland had led to the 12.6% and 5.1% growths in average annual surface runoff and total runoff, respectively. The conversion had also brought in a significant spatial difference in average annual surface runoff on the basin. The overall trend in the spatial difference had been increasing, which is primarily caused by the transformation of land use from forest to others. Changes in surface runoff in the upstream catchment area controlled by the Sandaohezi hydrological station was mainly the result of farmland landscapes. The paper concludes that reasonably planning of land-use pattern is important for the sustainable use of water resources in the Luanhe River basin.
Application of flexible-structure hydrological models in different runoff generation regions
LI Zhijia, HUANG Pengnian, YAO Cheng, LI Qiaoling, ZHAO Lixia, YU Zhongbo
2014, 25(1): 28-35.
Abstract:
The choice of an appropriate model to be applied to a given catchment for hydrological simulation is a challenging task in hydrology research. To address this issue, extensive research efforts have been devoted to the use of flexible-structure models in recent years. Four typical conceptual models and four flexible-structure models were applied to eleven Chinese catchments divided into the saturation excess, infiltration excess and mixed runoff generation regions. The results show that, in the saturation excess runoff generation region, it is difficult to improve the simulation accuracy by using the flexible-structure models. However, these models can be used to investigate the effect of model components on the simulation results and remove unreasonable model structures for this region. Although the flexible-structure models are able to produce the improved simulations in the infiltration excess runoff generation region, they present less systematic characteristics and cannot accurately represent full hydrological processes. Generally, the flexible-structure models exhibit unstable performance and poor versatility. However, these models are easy to build and modify, and have contributed to the identification of key processes of the runoff generation and concentration. Therefore, the flexible-structure models can be used as an efficient and robust tool for hydrological simulation.
On threshold of drought and flood disasters in Huaihe River basin
GAO Chao, CHEN Shi, ZHAI Jianqing, ZHANG Zhengtao, LIU Qing
2014, 25(1): 36-44.
Abstract:
Based on the daily precipitation from 110 stations in the Huaihe River Basin during 1959—2008, the crop damage area due to drought and flood disasters from 1978 to 2008, the hazard factor from precipitation, the extent of damage for crops, and the spatial-temporal characteristics of disasters are analyzed. The thresholds of drought and flood disasters are calculated and the relationships between the thresholds of drought and flood disasters and the crop damage area are established. The result shows that first, the thresholds of drought and flood disasters can be calculated using the ratio of the cumulative event precipitation to the mean cumulative precipitation of 1959—2008. The ratio can well reflect the severity of flood and drought disasters of varying degrees, and can meet the requirements for analyzing flood and drought events in the study area. Second, the drought and flood disasters quantified by the calculated thresholds can reflect all degrees of drought and flood disasters and the affected areas. The thresholds and the affected areas have similar variation tendency. In particular, the threshold of drought disaster and the crop damage area are highly correlated as revealed by the high value of correlation coefficient (0.96). Thus, a model for forecasting the crop damage area is developed based on the threshold of drought disaster.
Drought and wetness variability in the Tarim River basin and possible associations with large scale circulation
TAO Hui, MAO Weiyi, HUANG Jinlong, ZHAI Jianqing
2014, 25(1): 45-52.
Abstract:
Drought and wetness indices are important elements since they closely associated with water and energy balance over a geographical area and extending along a certain period of time. Studying of possible cause of drought and wetness variability is of great importance to understand the hydrological cycle and disaster reduction. Based on daily observations of 39 meteorological stations in the Tarim River basin, the spatial and temporal variability of drought and wetness has been analyzed using the standardized precipitation evapotranspiration index (SPEI). The result shows an increasing trend in annual mean SPEI with a significant change point in 1986. Although the frequency of moderate and severe drought decreased after 1986, the frequency of extreme drought events increased slightly. But different categories of wetness show a consistent increase in frequency. Furthermore, we also investigated the corresponding atmospheric circulation anomalies of drought and wetness changes over the Tarim River Basin using NCEP-NCAR reanalysis datasets. Composition analysis of geopotential height and wind field at 500 hPa are performed for typical extreme dry and wetness month as well as for the warm seasons (MJJASO)of the periods 1961 to 1986 and 1987 to 2010, the result shows obvious difference in large scale circulation pattern can be found in typical wet and dry months, the intensified water vapor transportation and unstable atmospheric stratification are the main reasons of the wetter condition in warm seasons after the 1980s.
Snowmelt runoff simulation driven by APHRODITE precipitation dataset
LI Lanhai, SHANG Ming, ZHANG Minsheng, AHMAD Sajjad, HUANG Yue
2014, 25(1): 53-59.
Abstract:
A snowmelt runoff model (SRM) was modified and applied to simulate the snowmelt runoff process in the Kaidu River basin in the Xinjiang Autonomous Region of China. The modified model was driven by the precipitation product of the Asian Precipitation-Highly Resolved Observational Data Integration Towards Evaluation (APHRODITE) of the Water Resources project. The daily effective active temperature was used in the model as the degree-days to replace the daily mean temperature for estimating the snowmelt rate. In order to reflect the effect of seasonal frozen soil on runoff, the accumulated active temperature was proposed to represent the state of seasonal frozen soil, and the runoff coefficient was modified using the accumulated active temperature. Using the meteorological and hydrological data observed from the Kaidu River basin, along with snow products from the Moderate Resolution Imaging Spectroradiometer (MODIS), the modified SRM was employed to simulate the runoff in the Kaidu River basin during snowmelt seasons. SRM was calibrated and validated using 2000 and 2006 data, respectively. Based on the coefficient of determination and the difference between simulated and observed runoff, calibrated and validated results simulated by the modified SRM using the daily effective active temperature as the degree-days were much better than that using the daily average temperature as the degree-days. The result shows that the interpolated APHRODITE precipitation data, the modified degree-days and runoff coefficient, expressed with the effective accumulated temperature as the SRM model inputs, can reflect the snowmelt runoff process in the Kaidu River Basin and greatly improve the snowmelt runoff simulation accuracy.
A study of freezing process in variably-saturated sandy-loam soil under different water table depths:Experiment and simulation
WU Mousong, HUANG Jiesheng, TAN Xiao, WU Jingwei
2014, 25(1): 60-68.
Abstract:
Two soil column freezing experiments were conducted to understand the effect of water table depths on the transport of water, heat, and salt in soil columns. Column A was 60 cm soil in height but without water recharge, while column B involved a stable water table at 60 cm depth from the soil surface. While the soil was freezing, water content and temperature were measured. Results show that water and salt move upwards during the freezing process, and accumulate at the freezing front when there is a shallow water table. The movement of water and salt brings heat to the frozen soil. Such a redistribution of heat in the soil column can slow the progress of a freezing front. The HYDRUS-1D freezing and thawing module was used to simulate water movement and heat transfer during freezing at different water table depths (0.5 m, 1.0 m, 1.5 m, 2.0 m, and 2.5 m). Results show that the shallower the water table, the smaller the cumulative recharge, that is, a shallow water table supplies water more intensely and seems to stop the progress of the freezing front; a deeper water table has difficulty in recharging the upper layers.
Experimental study on water evaporation from Fontainebleau sand using an environmental chamber
SONG Weikang, DING Wenqi, CUI Yujun
2014, 25(1): 69-76.
Abstract:
To investigate the mechanism of soil water evaporation, water evaporation experiment was performed on Fontainebleau sand in a large-scale environmental chamber under controlled atmospheric conditions and with a constant water table at the bottom of soil sample. Both the evolutions of atmospheric parameters (air temperature, relative humidity and air flow rate) and the changes of soil parameters (soil temperature, volumetric water content and matric suction) were monitored during the experiment. Emphasis was put on the measurement of matric suction at the soil surface. The actual evaporation rate and cumulative evaporation were also determined using the experimental data. Results show that the evaporation process is limited to the near surface zone; significant changes of soil volumetric water content and temperature in this zone were identified, whereas negligible changes were observed at deeper levels. Both air temperature and evaporation process have significant influence on the changes of soil temperature. The relative humidity at soil surface is related to the evaporation process. The soil matric suction increases during evaporation. The actual evaporation rate shows a clear three stages.
Lateral variation properties in river channels due to bank failure along the desert valley reach of upper Yellow River
SHU Anping, GAO Jing, LI Fanghua
2014, 25(1): 77-82.
Abstract:
By means of field survey and measurement data analysis, the types of river bank erosion along the desert wide valley reach of the upper Yellow River can be classified into two types: cohesive bank and non-cohesive sand accumulation bank, according to the river bank material composition and the sediment source. The former type can be further classified into three subtypes: plane collapse, arc collapse and cantilever collapse, whereas the latter has two subtypes of erosion: surface sliding and plane collapse. Taking the Dengkou reach and the Wuhai reach for examples, and combining with remote sensing image interpretations for nearly 10 years, the shoreline variations are analyzed to reveal the lateral variation in the reaches due to bank failure. Results show that the bank collapse rate of cohesive bank erosion is greater than that of non cohesive sand accumulation bank erosion. In the short term, there appears to be formations of concave bank and accretion of convex bank in local bending channels, but in the long term, the whole reach tends to be in the overall trend of siltation. Therefore, the study has great significance to revealing the channel lateral deformation and the fluvial processes due to bank failure in the upper Yellow River.
Numerical simulation of bank erosion processes with composite materials and variations in flow structure
JIA Dongdong, HEI Pengfei, SHAO Xuejun, ZHANG Xingnong
2014, 25(1): 83-89.
Abstract:
Riverbanks with composite materials are commonly found on alluvial rivers. Lateral erosion processes of such banks are very different along the vertical direction. On the basis of three-dimensional (3-D) flow and sediment transport model and mechanisms of riverbank erosion, a 3-D numerical method was developed for simulating bank erosion processes with composite materials using the adaptive grid scheme. The 3-D numerical method is applied to a conceptual meandering channel, and to simulate the variation of 3-D flow structure as erosion of the bank progresses. Results show that the main flow migrates towards the concave bank after the erosion of bank toes, and then, a new secondary flow structure with reverse direction compared to the initial secondary flow structure is formed on the bank toe. The main flow migrates further towards the concave bank after the collapse of upper layers, and the new secondary flow structure on the bank toe disappears. Again, the main flow migrates towards the concave bank after the erosion of bank toes. Thus, the main flow migrates towards the concave bank step by step, resulting in a continue bank erosion and channel migration.
Effects of rill development on runoff and sediment yielding processes
HE Jijun, GONG Huili, LI Xiaojuan, CAI Qiangguo
2014, 25(1): 90-97.
Abstract:
In order to understand the runoff-sediment yielding processes of rill erosion for different soils, the characteristics of runoff and sediment yield in rill development for Lou soil (silty clay loam) and loess soil were studied under different slope gradients and simulated rainfall conditions. Results show that the runoff generation occurred earlier and rills formed more easily within Lou soil than within loess soil. The rill formation exhibited a regular parallel distribution. The degree of rill development increased as the gradient increased, which could prolong the time of runoff generation. For loess soil, however, it was hard to generate runoff and induce rill formation. The rills that did form exhibited a random orientation. The processes of rill development did not have a significant effect on runoff yield; the soil infiltration rate was the major factor causing the difference in the runoff generation processes in the two soils. For Lou soil, the rate of sediment production increased with an increase in the degree of rill development. Sediment production stabilized early, and sediment concentration increased as rill density increased. For loess soil, the sediment concentration process largely depended upon the randomness in the rill development process. When the rill erosion was based on collapse, a sharp increase was noted in sediment concentration, where even low rainfall intensities could cause significant soil erosion.
Impacts of vegetation and pavement runoff concentration on rural roadside slope erosions in Three Gorge Reservoir area
LIU Yaojun, WANG Tianwei, CAI Chongfa, LI Zhaoxia
2014, 25(1): 98-105.
Abstract:
The development of road networks is beneficial to promoting mountainous region’s economy; however, it can cause a series of environmental issues, such as the serious soil erosion on roadside slopes. This study aims to evaluate the effectiveness of four vegetation restoration schemes in controlling the roadside slope erosion under simulated rainfall events. The schemes are natural restoration (NR), grass (GR), grass and shrub (GS) and sodded strip (SS). At the same time, rainfall simulation and scour test are conducted to quantify the contribution of pavement flow to fill slope runoff along roads and sediment production. Results show that the GS scheme has a higher capability to reducing rainfall runoff and sediment trapping compared to other three means. On the fill slope, both GS and GR schemes significantly outperform other twos in reducing rainfall erosion and pavement flow scouring. The pavement flow concentration has a remarkable effect on the acceleration of fill slope erosion, just as accelerated the runoff generation, the corresponding rainfall runoff and sediment yield are increased. For a best management of mountainous road erosions, apart from choosing a suitable preventive measure, more efforts should be focused on the road rational planning and design to better control runoff generation and concentration.
Incipient motion of sediment in wave and combined wave-current boundary layers
LI Shouqian, LU Yongjun, ZUO Liqin, HUANG Weihao, LU Yan
2014, 25(1): 106-114.
Abstract:
Based on the theory of wave boundary layers and the Shields curve, the criterion curve is developed for the incipient motion of sediment in a wave boundary layer in this study. Two factors (X and Y) are proposed to characterize the turbulent structure of wave-current boundary layers, and an empirical relationship between Y and X is established. Furthermore, a criterion curve is derived for the incipient motion of sediment in combined wave-current boundary layers. This is done through the consideration of individual criterion curves for waves only and currents only. Results show that the criterion curve for waves is consistent with the Shields curve for the laminar flow regime and for the rough turbulent flow regime, while for the laminar-rough turbulent flow transition regime, it follows a broken line distribution, which is the extension of the two flow regimes. The proposed two factors X and Y could reasonably describe the relative relation of waves and currents and the non-linear effect of wave-current interaction. The criterion curve for combined waves and currents transits between individual criterion curves for waves only and currents only, depending on the values of X and corresponding Y. The proposed criterion curve for combined waves and currents agrees well with the measured data and could be used for different hydrodynamic conditions (i.e., waves, currents, or their combined actions) and different particle sizes (i.e., from coarse to fine).
Mechanism of seabed scour and its critical condition estimation by considering seepage forces
WANG Hu, LIU Hongjun, WANG Xiuhai
2014, 25(1): 115-121.
Abstract:
The phenomena in the vicinity of seabed surface such as sediment movement are closely related to the wave-induced seepage in the seabed. In this study, the mechanism of seabed scour is investigated, and the estimation of critical conditions for the scouring due to wave-induced seepage force is discussed in detail. Results show that the incipient motion of sediment and the scouring under wave actions are a process that goes progressively downward from seabed surface until reaching a critical scour depth eventually. The critical incipient shear stress of sediment can be reduced and the incipient motion of sediment can certainly be promoted due to the wave-induced seepage force. The wave-induced seepage force is considered as an important driving factor in the estimation of critical conditions for the scouring. The seepage force is supplemented to the traditional formula for estimating the incipient motion of sediment, and a new method for the estimation of critical scour depth due to wave-induced seepage can thus be derived. Two case studies are performed. The "fluidization" phenomenon in the laboratory flume and the genetic mechanism of the submarine geological hazards such as the gully of the silt flow in the Yellow River delta are well explained. The effectiveness of the new method for estimating and assessing seabed scouring has been preliminary tested.
On source identification method for sudden water pollution accidents
YANG Haidong, XIAO Yi, WANG Zhuomin, SHAO Dongguo, LIU Biyu
2014, 25(1): 122-129.
Abstract:
In order to solve the source identification problem of sudden water pollution accident accurately and quickly, a method based on the Differential Evolution and Markov Chain Monte Carlo (MCMC) is presented. First, the problem is considered as a Bayesian estimation problem, and the posterior probability distribution of the unknown parameters that include source’s position, intensity and events’ initial time are deduced with Bayesian inference. Second, these unknown parameters are estimated by sampling the posterior probability distribution using the Differential Evolution algorithm and Markov Chain Monte Carlo simulation, and the sources are further identified. To test the effectiveness and accuracy of the proposed method, numerical experiments are carried out, and the model result is compared to that of the Bayesian-MCMC method. The conclusions are as following: three fourth of the iterations can be reduced, the average relative error of the source’s position, intensity and events initial time are reduced 1.23%, 2.23% and 4.15%, their mean errors are decreased 0.39%,0.83% and 1.49% by using the proposed method. The latter is thus more stable and robust than the Bayesian-MCMC method, and is able to identify the sudden water pollution accidents’ source effectively. Therefore, this study provides a new approach and method to solve the difficult traceability problem of sudden water pollution accidents.
Embedding regulatory water safety factor into a short-term optimal dispatch model for cascade reservoir operations
LI Yong, PEI Weizheng, LI Jia, LI Kefeng, ZHU Ming
2014, 25(1): 130-138.
Abstract:
In order to effectively ensure the needs for water safety during the short-term optimal dispatch of cascaded reservoirs, a model for cascade reservoir operation is established. A regulatory water safety factor is embedded into the model to achieve the water safety objective. A Vague set is used for the water safety measurement in the development of the model, and the regulatory water safety factor is the regulatory water safety factor is introduced for calculating the discharge constraint of the cascaded reservoirs, which is considered as part of water safety requirements. With the obtained discharge constraint, the regulatory water safety factor can thus be embedded into the short-term optimal dispatch model for cascade reservoir operations. The regulatory factor in the model can be defined according to the water safety requirements, and the corresponding short-term optimal dispatch scheme can thus be determined accordingly. The model is applied to optimize the cascade reservoir operation in the middle reach of Jialing River, consisting of three multipurpose reservoirs for navigation and hydroelectric power production. Results show that the model is able to achieve the maximum benefit from the short-term optimal dispatch of cascaded reservoirs, while ensuring the needs for water safety. Embedding the regulatory water safety factor into the model not only improves the benefit from cascade reservoir operations, but also preserves the water safety requirements.
Effects of flow and sediment on the transport and transformation of pollutants in rivers: A review
TANG Hongwu, YUAN Saiyu, XIAO Yang
2014, 25(1): 139-147.
Abstract:
Flow and sediment are known to be the main carriers of the transport and transformation of pollutants in rivers, and a better understanding of the effect of flow and sediment is therefore of crucial importance for the management of deteriorating water environment. This paper reviews the experimental studies on the effect of flow and sediment on the transport and transformation of pollutants in water, underlying mechanisms, and existing theoretical and mathematical models. In particular, a comparison is made between several models. However, it should be noted that there are some limitations in the experimental methods, the exact mechanism remains controversial, and the theoretical and mathematical models available seem to be not sufficient to characterize the transport-transformation process of pollutants. This underscores the need for further laboratory and field experiments on the interface kinetics of the particles, and theoretical investigation of the transport-transformation process of pollutant in the overlying or underlying water. At last, some directions for further studies are suggested in the study.
Research advances in risk assessment and enforcement of unsafe reservoirs
YANG Jie, ZHENG Chengcheng, JIANG Dejun, HU Dexiu
2014, 25(1): 148-154.
Abstract:
A large number of reservoirs in China face potential risks in their current status. Risk assessment and reinforcement of these reservoirs have been carried out nationwide step by step. Searching for theoretical approaches to reinforce the risk reservoirs has become an important subject at present. On the basis of reviewing existing literature, the current research on the risk reservoir reinforcement can be categorized into two aspects: the theoretical analysis approach and the reinforcement measures. Research advances in the former include the risk assessment, the safety evaluation, structural analysis methods, and the quantitative study of reservoir reinforcement. Considering the special status of risk reservoirs in China, future research should focus on the risk assessment, the safety evaluation, structural analysis methods, and the quantitative study of reinforcement measures for high risk reservoirs.