Entity

Time filter

Source Type


Chen Z.H.,Sun Yat Sen University | Chen Z.H.,Guangdong High Education Institute | Fang H.W.,Tsinghua University
Science China Technological Sciences | Year: 2013

The morphology of sediment particles plays an important role in interfacial interactions. The difficulties in complex morphological description significantly limit the research on interfacial interactions. In this study, images of a single sediment particle extracted from electron microscope photos were used to analyze the gray values and present the probability of shape of the sediment particles. Moreover, the morphological features of the sediment particles were qualitatively described using the fractal method (surface area-volume method). The fractal dimension D of a single sediment particle was calculated to analyze the features and quantitative complexity of the sediment particle morphology. Results indicate that the probability of shape can provide intuitive morphological structure and fully describe the complex morphological characteristics of sediment particle surfaces. The fractal dimension abstractly described the complexity of the morphology of a sediment particle surface and matched well with the experimental results. The methods discussed in this study are suitable for describing the complex morphology of the sediment particle surface and lay the scientific foundation for further research on the interfacial interaction between the sediment particle and the pollutant. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg. Source


Xiong Y.J.,Sun Yat Sen University | Xiong Y.J.,Guangdong High Education Institute | Chen Z.H.,Sun Yat Sen University | Chen Z.H.,Guangdong High Education Institute | Tan S.L.,Sun Yat Sen University
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2013

Sea surface salinity (SSS) is of great important to physical, biological, and chemical oceanographers. Although a challenge, it is possible to measure SSS from space using remote sensing data. However, existed SSS product is only useful for large scale research, i.e. open ocean (with area larger than of 200 × 200 km2), but may play a minor role at local scale study such as in monitoring seawater intrusion in estuary. Therefore, objective of this study is to investigate the relationship between salinity and remotely sensed sea surface temperature. A case study was carried out using MODIS sea surface temperature (SST) product and observational chlorosity in the Pearl River Estuary, China. The results concluded were that a polynomial regression model shows that salinity might be estimated using SST as the mean absolute error is 2.95‰ and in most cases absolute errors were less than 1.2‰. © 2013 IEEE. Source


Xiong Y.,Sun Yat Sen University | Xiong Y.,Guangdong High Education Institute | Chen X.,Sun Yat Sen University | Chen X.,Guangdong High Education Institute | And 2 more authors.
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2011

Chlorophyll a (Chl-a) is an indicator of water quality, especially of eutrophic state. Remote sensing has been used to mapping Chl-a in lake, large river, estuary and ocean, due to its advantages such as to provide data logistically and economically. The aim of this paper was to use LandSat TM image and suitable algorithm to estimate and map Chl-a concentration in reservoir Dajingshan, an important source for drinking water supply in Zhuhai city, China. After comparing several simple linear regression algorithms, a most suitable algorithm using brightness value of bands 1 to 4, was adopted. The results showed that the modeled chl-a concentration in November 23th, 2005 had reasonable accuracy, with a mean absolute error of 0.002 mg/L when compared with the ground truth measurements. The chl-a concetration map showed that the reservior Dajingshan was in eutrophic conditions and the water could not be used as drinking water. © 2011 IEEE. Source


Zhang Z.H.,Sun Yat Sen University | Zhang Z.H.,Guangdong High Education Institute | Zhang Q.,Sun Yat Sen University | Zhang Q.,Guangdong High Education Institute | And 3 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2016

Allocation of water resources from river basins draining into reservoirs is a challenging task, particularly, if the ecological water requirement is taken into account. In this study, copula functions were used to analyze hydrologically the possible synchronous occurrence of dry and wet regimes in the Liaohe River. The ecological streamflow requirements were considered during the water resource allocation. The following results were obtained. (1) The probability distribution with the highest goodness-of-fit for the Yinna River and Zhangjiabao reservoir inflow was the log-normal distribution and that for the reservoir inflow of other rivers was the generalized extreme-value distribution. Further, the Gumbel and Frank copulas had the best fitting efficacy for the inflow series of the reservoirs. (2) The synchronous wet/dry events occurred at a higher probability of more than 27% at 4 out of 7 pairs of water reservoirs and at the rate of 13%, 12%, and 13% at the other three pairs of water reservoirs, i.e., Baishi vs. Jinling, Baishi vs. Qingshan, and Zhangjiabao vs. Biliuhe, respectively. Further, the probability of synchronous dry instream events was high in these reservoirs. (3) The method of minimal monthly runoff at 90% guarantee rate suggest the best ecological runoff at the nine water reservoirs. (4) Dry-dry events occurred at a higher frequency during low-flow periods. The water resource allocation or operation cannot be executed when the reservoir instream flow is lower than the minimum ecological streamflow. Joint water operation of the reservoirs based on the occurrence probability of dry-dry events and minimum ecological streamflow can satisfy the regional water requirement. © 2016, Ecological Society of China. All rights reserved. Source


Chen Z.,Sun Yat Sen University | Chen Z.,Guangdong High Education Institute | Yin L.,Sun Yat Sen University | Yin L.,Guangdong High Education Institute | And 6 more authors.
International Journal of Climatology | Year: 2015

Extreme precipitation occurs frequently because of hydrological variability, resulting in humid cities facing serious waterlogging problems. Previous studies about rainstorms had emphasized on spatial-temporal distribution characteristics, but rarely on rainfall pattern (RP). With a typical humid city in southern China, such as Guangzhou City in Guangdong Province as the research object, hourly precipitation data from January 2009 to October 2014 are collected from five meteorological stations in Guangzhou. The data are counted and classified by fuzzy mode recognition method according to seven typical rainfall patterns (STRP) and the Huff rainfall pattern (Huff RP). Subsequently, the distributive characteristics of urban rainstorm pattern (RSP) are analyzed. The main results obtained are as follows: (1) annual rainstorm days have high positive correlation with rainfall days, and the annual amount of rainstorm contributes to 7.5-50.5% of the annual total rainfall in Guangzhou, (2) large-scale rainfall is highly possible to occur in Guangzhou, (3) most rainstorms in Guangzhou are unimodal, of which the frontal peak is more than 70%, and (4) STRP are appropriate for RSP division in Guangzhou City. © 2015 Royal Meteorological Society. Source

Discover hidden collaborations