Regional daily baseflow prediction     

Ching‐pin Tung  Nien‐ming Hong  Chu‐hui Chen  Yih‐chi Tan 《水文研究》2004,18(11):2147-2164

The purposes of this study are to identify the bias of applying the analysis of a log–log plot of baseflow and to derive an equation to describe successive regional mean baseflow. The function ?dQ/dt = a Q^b has been used to describe baseflow in many studies that obtain the values of a and b from the log–log plot. According to analysis in this study, the value of 1 can be assigned to b in two boundary conditions, but the parameter a is proved to be related to the depth of water table and starting time of recession and thus different values of a may be found for different recession events. This paper points out that no single regression line can be obtained by plotting all baseflow data on a log–log diagram. Instead, there should be parallel lines, and each for a recession event. It implies that no single set of parameters a and b can be applied to predict baseflow. Thus, a new equation describing the relationship between three successive mean baseflows was derived in this study. The bias in the analysis of the log–log plot and the ability of the derived equation to predict baseflow were verified for five watersheds in Taiwan. Results indicate that the formula of mean baseflow prediction can provide reasonable estimates of flows with a leading time of 6 days. Furthermore, stream flows of the Tonkawa creek watershed in USA were used to verify that using average flows can result in better predictions than using instantaneous flows. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Analytical solutions of infiltration process under ponding irrigation     

Jiann‐Mou Chen  Yih‐Chi Tan 《水文研究》2005,19(18):3593-3602

The objective of this paper is to simulate the progress of the soil water content distribution in the soil profile with a water table at the bottom of the soil profile during ponding irrigation. This simulation can be done by solving the two‐dimensional Richards's equation for the assimilation of the advancing water jet, which uses the conditions of the two exponential functional forms k = k_s e^αψ and θ = θ_r + (θ_s − θ_r) e^αψ to represent the hydraulic conductivity and volumetric water content, with ψ the pressure as the third variable. We assume that the ground surface becomes ponded and saturated as soon as the water flux passes the dry ground surface. By the technique of transformation, the analytical solution of these two‐dimensional Richards' equations has enabled figures of volumetric water content distribution to be obtained in successive time periods after irrigation. For the example of loam soil, it can simulate the variation of volumetric water content during and after irrigation in the soil profile. The analytical solutions of this paper reflect the real situation simulated, and can be applied to verify those complicated solutions from other analytical models. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Application of sub-image multiresolution analysis of Ground-penetrating radar data in a study of shallow structures     

Yih Jeng  Chun-Hung Lin  Yi-Wei Li  Chih-Sung Chen  Hung-Ming Yu 《Journal of Applied Geophysics》2011,73(3):251-260

Fourier-based algorithms originally developed for the processing of seismic data are applied routinely in the Ground-penetrating radar (GPR) data processing, but these conventional methods of data processing may result in an abundance of spurious harmonics without any geological meaning. We propose a new approach in this study based essentially on multiresolution wavelet analysis (MRA) for GPR noise suppression. The 2D GPR section is similar to an image in all aspects if we consider each data point of the GPR section to be an image pixel in general. This technique is an image analysis with sub-image decomposition. We start from the basic image decomposition procedure using conventional MRA approach and establish the filter bank accordingly. With reasonable knowledge of data and noise and the basic assumption of the target, it is possible to determine the components with high S/N ratio and eliminate noisy components. The MRA procedure is performed further for the components containing both signal and noise. We treated the selected component as an original image and applied the MRA procedure again to that single component with a mother wavelet of higher resolution. This recursive procedure with finer input allows us to extract features or noise events from GPR data more effectively than conventional process.To assess the performance of the MRA filtering method, we first test this method on a simple synthetic model and then on experimental data acquired from a control site using 400 MHz GPR system. A comparison of results from our method and from conventional filtering techniques demonstrates the effectiveness of the sub-image MRA method, particularly in removing ringing noise and scattering events. Field study was carried out in a trenched fault zone where a faulting structure was present at shallow depths ready for understanding the feasibility of improving the data S/N ratio by applying the sub-image multiresolution analysis. In contrast to the conventional methods, the MRA sub-image filtering technique provides an overall improvement in image quality of the data as shown in the field study.  相似文献   

Multivariate approaches optimize locations of groundwater pumping facilities for different hydrogeological scales     

Hsien‐Tsung Lin  Yih‐Chi Tan  Chu‐Hui Chen  Wen‐Sheng Lin  Chen‐Wuing Liu 《水文研究》2012,26(19):2985-2996

A number of optimization approaches regarding the design location of groundwater pumping facilities in heterogeneous porous media have elicited little discussion. However, the location of groundwater pumping facilities is an important factor because it affects water resource usage. This study applies two optimization approaches to estimate the best recharge zone and suitable locations of the pumping facilities in southwestern Taiwan for different hydrogeological scales. First, for the regional scale, this study employs numerical modelling, MODFLOW‐96, to simulate groundwater direction and the optimal recharge zone in the study area. Based on the model's calibration and verification results, this study preliminarily utilizes the simulated spatial direction of groundwater and compares the safe yield for each well group in order to determine the best recharge zone. Additionally, for the local scale, the micro‐hydrogeological characteristics are considered before determining the design locations of the pumping facilities. According to drawdown record data from six observation wells derived from pumping tests at the best recharge area, this study further utilizes the modified artificial neural network approach to improve the accuracy of the estimation parameters as well as to analyse the direction and anisotropy of the hydraulic conductivities of an equivalent homogeneous aquifer. The results suggested that the best locations for the pumping facilities are along the more permeable major direction. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

ATTITUDES TOWARDS SERVICE PROVISION IN PUBLIC HOUSING ESTATES AND NEW TOWNS IN SINGAPORE     

Teo Siew Eng  Ph.D.  David R. Phillips  Ph.D. 《Singapore journal of tropical geography》1990,10(1):74-94

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Enzyme variation in marine and estuarine populations of a mud crab,Macrophthalmus hirtipes (Ocypodidae)     

F.Y.T. Sin  M.B. Jones 《新西兰海洋与淡水研究杂志》2013,47(4):367-372

Protein and enzyme variation in 2 populations of the mud crab Macrophthalmus hirtipes (Jacquinot, 1853) (Ocypodidae) from 1 marine and 1 estuarine habitat were investigated by poly‐acrylamide gel electrophoresis. A survey of 24 loci revealed that 22 were common to both populations; 20 were monomorphic and 2 were highly polymorphic. Two alleles were detected for each of the polymorphic loci, esterase‐2 (EST‐2) and ester‐ase‐3 (EST‐3). The frequencies of the EST‐3 alleles were similar in the 2 populations. However, the frequencies of the 2 EST‐2 alleles in the estuarine population were significantly different from those for the marine population. Expression of 1 locus, esterase‐4 (EST‐4) was confined to the estuarine population. Two alkaline phosphatase loci (AKPH‐1 and AKPH‐2) were detected in the estuarine population, but only AKPH‐1 was found in the marine population. EST‐4 and AKPH‐2 were neither sex nor age specific. These interpopulational genetic differences may reflect differences in environmental conditions measured between the 2 habitats.  相似文献   

Editorial Note     

Teo Siew Eng  Brenda Yeoh 《Singapore journal of tropical geography》1997,18(1):no-no

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Changes in Cu Characteristics and Precipitation during Cu Merging     

A. A. Sin’kevich  V. B. Popov  I. A. Tarabukin  E. V. Dorofeev  Yu. A. Dovgalyuk  N. E. Veremei  Yu. P. Mikhailovskii  V. S. Snegurov  A. V. Snegurov 《Russian Meteorology and Hydrology》2018,43(8):506-515

The results of investigation of convective cloud merging observed near Saint Petersburg are presented. Data obtained with a set of remote sensing instruments (radar, radiometer, and lightning location system) were analyzed. Rain gage network data are used. Clouds simulation is performed using a 1.5-dimensional nonstationary model. A method to calibrate the radar measurements to obtain precipitation characteristics using rain gage network data is developed. According to radar data, a 2-km increase in the cloud top height was observed after Cu merging, the maximum reflectivity of clouds increased at 10 dBZ, maximum rain intensity and rain flux increased by about two times. The increase in rainfall intensity is also corroborated by rain gage observations and numerical simulations. An increase in the intensity of lightning discharges during the merging is registered.  相似文献   

Investigation of Cu cong Seeding Effect during Rainfall Augmentation in India     

A. A. Sin’kevich  B. Boe  Yu. P. Mikhailovskii  Yu. A. Dovgalyuk  N. E. Veremei  V. Gopalakrishnan  P. Murugavel  S. D. Pawar 《Russian Meteorology and Hydrology》2018,43(4):209-217

The results are presented of complex investigation of clouds in India which were seeded with a glaciogenic reagent from the aircraft. The seeding effect was assessed by the comparison of radar characteristics of the seeded clouds with the characteristics of clouds within the radar field of view. The maximum reflectivity increase in the seeded clouds in comparison with clouds in the natural cycle, an increase in the precipitation flux and specific mass of precipitated hail are observed. The merging of seeded clouds was observed during the study. It is shown that this process affects cloud characteristics resulting in the significant (by several times) increase in the precipitation flux. The measurements of electric discharges registered by the lightning detection network demonstrated that there were no lightning strikes in the seeded clouds, although the calculations indicated an increase in the electric activity of the clouds.  相似文献   

Investigations of the development of thunderstorm with hail. Part 3. Numerical simulation of cloud evolution     

A. A. Sin’kevich  Yu. A. Dovgalyuk  N. E. Veremei  A. B. Kurov  Yu. P. Mikhailovskii  E. V. Bogdanov  M. L. Toropova  A. A. Ignat’ev  A. Kh. Adzhiev  A. M. Malkarova  A. M. Abshaev  V. Gopalakrishnan  P. Murugavel  S. D. Pawarr 《Russian Meteorology and Hydrology》2017,42(8):494-502

The three-dimensional nonstationary model of a convective cloud is used for investigating a thunderstorm with hail which developed over Pyatigorsk on May 29, 2012 and produced a severe hailstorm. The values of cloud characteristics (liquid water content, ice content, vertical velocity, etc.) are obtained. The importance ofconsidering wind shear is noted. The simulation results are used to analyze the transformation of precipitation field and the electric charge structure of the analyzed cloud during its development.  相似文献