• 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

2012 Vol. 23, No. 5

Display Method:
Driving forces analysis and estimation of agriculture drought in river basins using regional climate model
WU Di, PEI Yuan-sheng, ZHAO Yong, YAN Deng-hua
2012, 23(5): 599-608. doi: CNKI: 32.1309.P.20120614.2158.006
Abstract:
Taking the Mekong River basin as the study area, this paper analyzed and estimated the changes of agricultural drought on a monthly scale in terms of the typical index of soil water content in the root layer. The regional climate model (RegCM3) under the A1B scenario is used in the simulation of soil water content and other surface variables. Based on the theory of surface energy balance, it systematically analyzed the relationship and variation between the main factors of agricultural drought (such as precipitation, evaporation, surface temperature and soil water content of root layer) and atmosphere circulation, surface energy fluxes (such as sensible flux, latent heat flux, surface net flux) simulated by RegCM3. Through land surface water and energy fluxes balance, this paper identified preliminarily the occurrence mechanism of agriculture drought in the Mekong River basin. The estimation indicated that the surface temperature would increase obviously, but the soil moisture could decrease remarkably in late spring (June) and autumn (October). During the latter two periods, the study area is likely to experience a reduction in precipitation and an intensification of evapotranspiration, which could lead to the occurrence of agricultural drought in the study area especially in the non-irrigated agricultural regions.
Estimation of evapotranspiration over the Yellow River’s source area from national geostationary meteorological satellite data
LIU Rong, WEN Jun, WANG Xin, TIAN Hui, ZHANG Yu
2012, 23(5): 609-615. doi: CNKI: 32.1309.P.20120824.1606.001
Abstract:
The evapotranspiration (ET) from the source area of the Yellow River was estimated from the national geostationary meteorological satellite data and ground observation for September 2009. The ET estimation uses the energy balance approach. Under clear-sky conditions, the Surface Energy Balance System (SEBS) model can be applied for the ET estimation; whereas under cloudy conditions, the ET estimation is based on the solar radiation for different cloudy conditions, which considers the solar radiation attenuation process in the atmosphere. The result shows that the average daily estimated ET varies between 2.0 mm and 3.0 mm with a single-peak value in the source area, and compares well to the ground measurements with an average relative error of 15.2%.
Onset of flood season in the middle reach of Yellow River, Qinhe River and Yongding River and summer monsoon strength in the Qing dynasty
PAN Wei, MAN Zhi-min, ZHUANG Hong-zhong, YE Sheng
2012, 23(5): 616-620. doi: CNKI: 32.1309.P.20120824.1606.002
Abstract:
The time series of flood season onset date anomalies are established on a pentad scale (or a 5-day scale) in the Qing dynasty. A water level rise of 0.64 m marks the beginning of a flood season. The historical water level records of the Qing Government are obtained for Wanjingtan near the Sanmenxia Gorge in the middle reach of the Yellow River, and Muluandian in the lower reach of Qinhe River, as well as Shijingshan and Lugouqiao Bridge in the lower reaches of Yongding River. The records start respectively in 1766, 1736 and 1761 for the Yellow River, the Qinhe River and the Yongding River. During the study periods, the flood season usually started between July 6 and July 10 in the middle reach of the Yellow River and the lower reach of the Qinhe River; whereas in the Yongding River, the season normally started between July 16 and July 20. The starting date is found to be more stable in the Yongding River comparing to the other two rivers. This is due to the fact that the rainy season is very much regular in early July in the upstream region of the Yongding River. However, the rainy season showed a great deal of fluctuation for up to three months in the middle reach of the Yellow River and the lower reach Qinhe River. The synchronous phase fluctuation in flood season onset date anomalies was more significant in the middle reach of the Yellow River and the lower reach Qinhe River after the mid-19th century. The flood season was generally postponed by 5 days in all three rivers during the period 1870-1990, which corresponded well with relatively cool summer temperatures observed on the Loess Plateau. The opposite was true in the middle reach of the Yellow River and in the lower reach of Qinhe River, which also corresponded well with relatively high summer temperatures observed on the Plateau.
Variation characteristics of stable isotopes in precipitation and river water in Fenghuoshan permafrost watershed
LIU Guang-sheng, WANG Gen-xu, SUN Xiang-yang, GAO Yang
2012, 23(5): 621-627. doi: CNKI: 32.1309.P.20120824.1606.003
Abstract:
Due to the complexity of the influence of freeze-thaw of active soil layer on water cycle, the hydrological observation is rare and difficult in permafrost watershed. In order to improve hydrological understanding in permafrost watershed, stable isotopes have proven utility since they reflect the integration of processes at smaller scales. Therefore, the spatial-temporal variation of stable isotopes in precipitation and river water of Fenghuoshan permafrost watershed was investigated, on the basis of variations in stable hydrogen and oxygen isotopes ratios (δD and δ18O) for precipitation and river water during June to October, 2009. The seasonality of stable isotopes for rain water suggests that the alternative influence of both continental air mass and monsoon air mass to local precipitation. The temporal-spatial distribution of stable isotopes for river water was influenced by the seasonality variation of river recharge from soil water and underground water and spatial difference of vegetation coverage. Along with the migration of freeze-thaw front of active soil layer, the source of river water and the variation characteristics of stable isotopes for river water changed. This suggests that the freeze-thaw of active soil layer plays an important role in rainfall-runoff process in permafrost watershed. In addition, evaporation played important role in the fractionation of water isotopes.
Capacity of soil water storage and regulation under different density forests of Tamarix chinensis Lour in coastal wetland
XIA Jiang-bao, KONG Xue-hua, LU Zhao-hua, LIU Jing-tao, HAN Rui-dong, ZHU Jin-fang
2012, 23(5): 628-634. doi: CNKI: 32.1309.P.20120614.2251.015
Abstract:
The objective is to explore the suitable forest density of Tamarix chinensis Lour on the capacity of soil water storage and regulation of wetlands in Yellow River Delta. The characteristics of soil water physical properties, soil infiltration, soil water storage and regulation of Tamarix chinensis under different density forests are analyzed. Soil infiltration course and hydrological properties are determined in field and laboratory. The results show that: ① The amount of fine sand increased with the density forests of Tamarix chinensis increasing, while the amount of silt and clay decreased. The effect of controlling soil salinity and alkaline content of middle density forest is better than that of high and low density forests, and the soil salinity and alkaline content of 0-20 cm is lower than that of 20-40 cm; ② Soil density decreased and then increased with the density forests of Tamarix chinensis increasing, while the soil porosity show a contrary tendency. Compared to the total porosity of low density forest, the increment of that in the middle, high density forest and grassland is 12.9%, 6.2% and 4.4%, respectively, and these indexes of 0-20 cm are better than that of 20-40 cm; ③ Soil infiltration course of forest field fitted Horton infiltration model well. Characteristics of soil infiltration show this order: Middle density forest>high density forest>low density forest> grassland; ④ Characteristics of soil saturated water content, soil capillary, non-capillary porosity water-holding capacity and total absorption precipitation show this order: Middle density forest>high density forest>grassland>low density forest, and the capacity of soil water storage and regulation in 0-20 cm is better than that of 20-40 cm. Compared to the capacity of total absorption precipitation in low density forest, the increment of that in the middle, high density and grassland is 28.4%, 23.8% and 14.1%, respectively. The largest capacity of soil water storage and regulation is the middle density forest, followed by high density forest, and low density forest is poor.
Correlative analysis of pedodiversity and spatial distribution of water body diversity at different scales in Central and East China
DUAN Jin-long
2012, 23(5): 635-641. doi: CNKI: 32.1309.P.20120824.1606.004
Abstract:
Five study areas with different sizes from Central and East China are selected for a correlative analysis between the diversities of soil constituents and water body spatial distributions. Remote sensing data for 2000-2001 and 2004-2006 are used to classify the land cover types and the land-use maps in the study areas. The information is further processed to produce the pedodiversity indices and the diversity indices of water body spatial distributions at a resolution of 2 km×2 km. The correlative analysis is then conducted to explore the inherence relationship between the two index types. Results show that it is maneuverable and practical to apply the diversity theories and approaches to studying the spatial discreteness in water resources distributions. The soil type numbers can be related to the area sizes in study areas. There is a positive relationship between the variations of area sizes and spatial distributions of water body diversity. The relationship is supported by over 70% data. However, there is no absolute linkage between the proportion of water and the spatial distribution of water body diversity. The fractal characteristics and structures are found in both soil and water data samples. There is a negative relationship between the diversities of soil constituents and water body spatial distributions. The correlation coefficient R2 can be as high as 0.8 at a large spatial scale.
Sensitivity analysis of hydrological model parameters using a statistical theory approach
SONG Xiao-meng, KONG Fan-zhe, ZHAN Che-sheng, HAN Ji-wei
2012, 23(5): 642-649. doi: CNKI: 32.1309.P.20120614.2158.003
Abstract:
The sensitivity analysis is a key step in model uncertainty quantification. And it can identify the dominant parameters, reduce the model uncertainty, and enhance the model optimization efficiency. In order to make quantitative global sensitivity analysis (GSA) more tractable, the Morris screening method is used to qualitatively assess a model first. Then, the response surface methodology (RSM) based on the statistical theory will be applied to construct a surrogate model, and to integrate with the variance-based Sobol' method to establishing a new method, named as the RSMSobol method. The new method is tested on the Yanduhe basin using the Xinanjiang model with daily precipitation data and hydrographs. The sensitivity analysis is conducted for four different objective functions. The results demonstrate that the new integrated qualitative and quantitative method can improve the efficiency of the sensitivity analysis, in which the Morris qualitative method can decrease the number of parameters by 50% for the next round of the quantitative analysis. The RSMSobol method can improve the computational cost.
Critical rainfall characteristics for rainfall-induced debris flows in Wenchuan earthquake affected areas
ZHOU Wei, TANG Chuan, ZHOU Chun-hua
2012, 23(5): 650-655. doi: CNKI: 32.1309.P.20120824.1606.005
Abstract:
The rainfall data before and after the occurrence of the debris flow event in Wenchuan earthquake affected area are collected and analyzed in order to better understand the critical rainfall characteristics for rainfall-induced debris flows. The study can provide the scientific base for the establishment of an advance warning system for debris flows. The results show that the critical rainfall pattern for the debris flow event during the earthquake can be classified into three types including the rapid triggering response pattern, the intermediate triggering response pattern, and the slow triggering response pattern. The main differences among the three patterns are in the duration and intensity of rainfall, which can result in different saturation mechanisms in loose zones for debris flow initiation. The timing of the occurrence of infiltration excess runoff is different for different rainfall patterns, and so do the triggered debris flows. Critical rainfall intensities could be related to critical rainfall patterns. For example, the intermediate triggering response pattern can be associated with the highest rainfall intensity, and followed by the slow triggering response pattern. The lowest rainfall intensity can be related to the rapid triggering response pattern. The threshold values of both accumulated precipitation and critical rainfall have been decreased after the earthquake.
Spatiotemporal variations of rice irrigation water requirements in the mid-lower reaches of Yangtze River under changing climate
WANG Wei-guang, PENG Shi-zhang, SUN Feng-chao, XING Wan-qiu, LUO Yu-feng, XU Jun-zeng
2012, 23(5): 656-664. doi: CNKI: 32.1309.P.20120824.1606.006
Abstract:
Projections of rice irrigation water requirements under future climate conditions can be beneficial in developing adaptation strategies for reducing the negative impact of climate change on rice productions and to ensuring the food security from the perspective of the sustainable use of water resources. Using a statistical downscaling model (SDSM), the projected daily reference evapotranspiration and precipitation of HadCM3 under A2 and B2 scenarios were downscaled to 45 local meteorological stations in the Mid-Lower Reaches of Yangtze River. Spatiotemporal variations of irrigation water requirements during the middle-season rice growing period for the past five decades (1961-2010) and future dates (2011-2099) were analyzed. The FAO (Food and Agricultural Organization) crop coefficient method and a water balance model considering the effective precipitation and deep percolation were used in the analysis. The results show that in the past five decades, significant decreasing trends in reference crop evapotranspiration and rice water demand can be detected in most regions of the Mid-Lower Reaches of Yangtze River except the Taihu Basin. While significant decreasing trends in paddy irrigation water requirements can only be observed in the Poyanghu Basin. Under both A2 and B2 scenarios, the mean reference crop evapotranspiration, paddy water demand and irrigation water requirements would decrease. However, the decrease in paddy irrigation water requirements would be greater than that in reference crop evapotranspiration and paddy water demand. Spatial heterogeneities could be found in changing trends in paddy water demand and irrigation water requirement. The region with greater decreasing paddy water demand would extend from the Taihu Basin to the Hanjiang River Basin and the Dongtinghu Basin. The decrease of paddy irrigation water requirements could be expected in the Taihu Basin, the eastern area of the Hanjiang River Basin and the northern area of the Dongtinghu Basin. The region with the decrease of paddy irrigation water requirements would be growing as time goes on.
Study of sediment transport by tsunami waves: Ⅰ: Beach profile evolution
JIANG Chang-bo, CHEN Jie, CHENG Yong-zhou, LONG Yuan-nan, DENG Bin
2012, 23(5): 665-672. doi: CNKI: 32.1309.P.20120824.1606.007
Abstract:
Tsunami has become one of the most serious marine disasters. The devastating tsunami waves can mobilize substantial amount of coastal sediment and change the coastal morphology considerably. 2D laboratory experiments were performed to investigate the changes of cross-shore beach profile under the wave action. The initial 1/10-1/20 composite beach slope was respectively exposed to the N-waves, regular waves and irregular waves in three water depths. The free surface elevations, processes of wave uprush, back wash and run-down jump, the change of cross-shore beach profile were measured and recorded. The study showed that the beach profile evolution was different under the action of N-waves, regular waves and irregular wave because of the different hydrodynamic characteristics. Erosion took place in the beach berm by sheet flow when the wave washed back. The seepage force contributed to incipient sediment motion. The deposition took place in the deeper region as the carrying capacity of sediment decreased in the offshore region where the run-down jumps happened. The beach profile was bar type.
Monitoring water flow process based on streaming potential forward model in unsaturated zone
YANG Lei, ZHOU Qi-you
2012, 23(5): 673-679. doi: CNKI: 32.1309.P.20120824.1606.008
Abstract:
Based on streaming potential forward model, the relationship between streaming potential and water flow process in unsaturated zone was studied in no rainfall condition and rainfall condition. The field data obtained in the research site of Zhongshan Botanical Garden in Nanjing was applied to compare with the results of numerical experiments. Field experiments showed that streaming potential method was efficient to detect the water flow process in unsaturated zone. If rainfall events didn't happen for a long time, the daily variations of temperature difference between soil surface and subsurface might induce water movements. By monitoring streaming potential signals in the field, the variations of water content and capillary head could be indicated and the water flow direction was pointed out at the same time. When a rainfall event happened, the water content and streaming potential were responsible for the migration of infiltration front immediately. According to the responses of different depth at different time, the movement velocity of infiltration front could be calculated directly.
On radial collector well structure of integrating seepage flow and pipe flow in the alluvial plain
LI Shen, DONG Xin-guang, WU Bin, YANG Peng-nian
2012, 23(5): 680-686. doi: CNKI: 32.1309.P.20120824.1606.009
Abstract:
The study is based on unsteady pumping tests in a radial collector well in the alluvial plain of Tailan river watershed in Aksu area of Xinjiang. The article develops the numerical model integrating seepage flow and pipe flow, which describes interactions between aquifer, well and horizontal arms. The model also accounts for diverse flow regimes and internal friction losses. Further, the developed model has been applied to simulate the effects of different aquifer hydraulic conductivity, radius of influence, equivalent hydraulic conductivity and drawdown on the yield of radial well in the coarse aquifer. And the proposed empirical equation based on the application of developed model and regression analysis gives a reasonable estimate of yield of radial collector well in the alluvial plain. It is recommended in optimizing lateral configuration and providing the basis for radial collector well arrangement.
Energy dissipater and cavitation characteristic study on gradual contraction and expansion discharge
YIN Ze-gao, ZHENG Qing-xin, WANG Le, CAO Xian-wei
2012, 23(5): 687-694. doi: CNKI: 32.1309.P.20120824.1606.010
Abstract:
Turbulence characteristics of sudden contraction and expansion discharge and gradual contraction and expansion discharge were analyzed respectively. A 3-D RNG k-ε turbulent model and a physical model were employed, respectively, and the computational results of turbulent model were validated by the physical model data approximately. Then the turbulent model was adopted to compute the head loss coefficient and the cavitation number. The results showed that under the given length of gradual contraction/gradual expansion, with the increase of gradual expansion length/gradual contraction length, the head loss coefficient decreases and the minimum cavitation number increases respectively. When the gradual contraction length exchanges with the gradual expansion length, head loss coefficient and minimum cavitation number vary little respectively. With the decrease of radius ratio of cross section, the head loss coefficient increases and the minimum cavitation number decreases respectively. As far as the arc connection is concerned, with the increase of arc angle, the head loss coefficient decreases firstly and then increases, but the minimum cavitation number increases firstly and then decreases. The head loss coefficient of arc connection is less than the oblique line connection does, and the minimum cavitation number of arc connection is more than the oblique line connection does. With the equal weight assumption of head loss coefficient and minimum cavitation number, an optimization method of gradual contraction and expansion parameters was discussed preliminarily, and the optimal geometry parameters were obtained.
Application of Runge-Kutta discontinuous Galerkin scheme for one-dimensional shallow water equations
ZHAO Zhang-yi, ZHANG Qing-he, LI Shi-sen
2012, 23(5): 695-701. doi: CNKI: 32.1309.P.20120824.1606.011
Abstract:
The Runge-Kutta discontinuous Galerkin scheme(RKDG), which maintains balance of flux and source terms, is formulated to solve one-dimensional shallow water flows in non-prismatic channel. To validate the numerical model, a transcritical flow over a hump in a non-prismatic channel and a hydraulic jump were simulated. The simulated results from RKDG agree well with the analytical solution and measured values. It is shown that the RKDG scheme developed in the present paper has proven its capability of capturing sharp waveform in discontinuous flows.
Experimental study on the sediment effect on releasing process of supersaturated total dissolved gas
FENG Jing-jie, LI Ran, TANG Chun-yan, YONG Xiao-dong
2012, 23(5): 702-708. doi: CNKI: 32.1309.P.20120824.1606.012
Abstract:
During its transportation over long distances, supersaturated Total Dissolved Gas (TDG) may lead to gas bubble disease or even heightened fish mortality. Because the sediment concentration is always high in spill flow in China, studying the releasing law of supersaturated TDG in sandy water is of great theoretical and practical value. In the experiment described in this paper, we designed three kinds of experimental conditions, including a static water column, stir-induced turbulent water and an open channel flow. For each experimental condition, the TDG release processes were monitored both in fresh water and sandy water. The dissipation coefficients were calculated and compared under different sedimentation levels. The results indicate that both sediment and turbulence intensity can increase the release speed of TDG. The higher the sediment concentration level and turbulence intensity are, the greater the dissipation coefficients are. This study can provide important guidance for determining dissipation coefficients in a TDG simulation model, and can serve as a reference in exploring mitigation measures of supersaturated TDG.
Numerical study of residence time and exposure time in Daliaohe Estuary
ZHANG Xue-qing, WANG Peng-cheng, SHI Ming-zhu, LIU Xiao-min, ZHAO Qian
2012, 23(5): 709-714. doi: CNKI: 32.1309.P.20120824.1606.013
Abstract:
To study the mass transport process in an estuary, residence time and exposure time were calculated for five boxes in Daliaohe Estuary in three typical runoff conditions using a three-dimensional convection-diffusion model based on Finite-Volume Coastal Ocean Model (FVCOM). Data were obtained for both the time required to leave the control domain for the first time and the total time spent in the control domain. Then, the return coefficient and the subdomain exposure time matrix which show the interaction between boxes were also investigated. The results showed the interaction between the runoff and tides control the residence time in Daliaohe Estuary. Exposure time and residence time have the same change trendency, but they differ greatly in size. Exposure times are 8, 3 and 1 days more than residence times during dry, normal and rainy seasons, respectively. The return coefficient could reach 0.94 at the downstream end during dry season, with the tracer returning to this area many times. The downstream boxes have little influence on the upstream boxes in Daliaohe estuary except for the case in the downstream end at the maximum flood tide.
Research on salinity mixing and stratification mechanisms at the Modaomen channel
REN Jie, LIU Hong-kun, JIA Liang-wen, CHEN Zi-shen
2012, 23(5): 715-720. doi: CNKI: 32.1309.P.20120824.1606.014
Abstract:
Based on Simpsons method and observation data of the Modaomen channel in the dry season in 2009, the paper discussed salinity mixing processes and stratification mechanisms with tidal straining, freshwater buoyancy inputs, stirring of wind at upstream and downstream stations. The results are as follows: (1) the impact of freshwater on stratification is weak at the upstream M1 station; and (2) stratification is obvious at downstream M2 station with continuous stratification during neap tide and cycle stratification during middle tide and spring tide, but stratification is strengthened during spring tide because of input freshwater increases. Weak stratification at the M1 station appears only at then maximum current during flood tide. Degree of stratification depends on ratio of Freshwater buoyancy to mixing inducing tide and wind.
Derivation and verification of a new generalized formula set for calculating maximum instantaneous dam breach discharge
FANG Chong-hui, FANG Kun
2012, 23(5): 721-727. doi: CNKI: 32.1309.P.20120824.1606.015
Abstract:
In order to calculate the maximum instantaneous dam-break discharge, a relationship between the maximum instantaneous dam-break discharge and the weir flow is established. The theory of equality of wave discharge and weir flow is applied in the study. A new generalized formula set is derived, which includes a basic formula, an up-limit formula, a low-limit formula and a generalized formula, etc. The verification results show that the new generalized formula set is capable of dealing with all types of breaches including whole dam collapse, horizontal partial dam-break, vertical partial dam-break, and both horizontal and vertical partial dam-break. The instantaneous dam-break discharge can be associated with the type of weirs. The new generalized formula set integrates equations for the instantaneous dam-break discharge, and the overtopping or gradually dam-break flood flow, as well as the corresponding coefficients into weir formulas. The values of the coefficients are reliable as they have been validated by available experimental data and classic scientific works. The new generalized formula set is validated with dam-break flow experiments and real-case data, and is proven to be rational and reliable.
Advances in hydrologic ensemble prediction experiment
LU Gui-hua, WU Juan, WU Zhi-yong
2012, 23(5): 728-734. doi: CNKI: 32.1309.P.20120824.1606.016
Abstract:
As a method for probabilistic forecasting, the hydrologic ensemble prediction provides deterministic forecast as well as uncertain information. The Hydrologic Ensemble Prediction Experiment (HEPEX) is an international initiative to advance probabilistic hydrological forecast techniques for flood, drought and water management applications. We review three recent HEPEX researches on the downscaling, ensemble prediction system and associated uncertainty issues in an effort to provide a useful platform for the development of hydrological forecasting. The results demonstrate that the applicability of the dynamical-statistical downscaling, and combining high-resolution with ensemble modeling system into operational practices, are the main direction for HEPEX future research.
Progress and prospect in risk assessment of hazards from glacier lake outbursts
WANG Shi-jin, QIN Da-he, REN Jia-wen
2012, 23(5): 735-742. doi: CNKI: 32.1309.P.20120824.1607.017
Abstract:
Glacier Lake Outburst Floods (GLOF) are natural hazards to the socioeconomic system in hazard regions. However, their predictions still remain worldwide challenge, and thus have attracted much attention in the scientific community as well as society at large. As a result, much progress has been made in risk assessment of hazards from glacier lake outbursts. This paper provides an overview of the subject both nationally and internationally. The reviews show that the previous studies focused mainly on the triggering mechanisms and characteristics of glacier lake outbursts, the risk assessment and probabilistic estimation of glacier lake outbursts, and the prediction of maximum GLOF discharge, as well as the GLOF simulation. However, only a few studies have been made on the risk assessment of vulnerability, exposure and adaptation for the socioeconomic system in hazard regions. Therefore, there is a need to enhancing the comprehensive risk assessment of hazards from glacier lake outbursts, towards a better understanding of the characteristics and dynamics of GLOF risks. The comprehensive risk assessment can provide an important theoretical reference to hazard preventions and mitigations, as well as the establishment of early warning system in hazard regions.