Hydrogeochemical characteristics of surface water and groundwater in the karst basin,southwest China   总被引：1，自引：0，他引：1  

Pan Wu  Changyuan Tang  Lijun Zhu  Congqiang Liu  Xuefang Cha  Xiuzhen Tao 《水文研究》2009,23(14):2012-2022

Groundwater is a very significant water source used for irrigation and drinking purposes in the karst region, and therefore understanding the hydrogeochemistry of karst water is extremely important. Surface water and groundwater were collected, and major chemical compositions and environmental isotopes in the water were measured in order to reveal the geochemical processes affecting water quality in the Gaoping karst basin, southwest China. Dominated by Ca²⁺, Mg²⁺, HCO₃^? and SO₄^2?, the groundwater is typically characterized by Ca? Mg? HCO₃ type in a shallow aquifer, and Ca? Mg? SO₄ type in a deeper aquifer. Dissolution of dolomite aquifer with gypsiferous rocks and dedolomitization in karst aquifers are important processes for chemical compositions of water in the study basin, and produce water with increased Mg²⁺, Ca²⁺ and SO₄^2? concentrations, and also increased TDS in surface water and groundwater. Mg²⁺/Ca²⁺ molar ratios in groundwater decrease slightly due to dedolomitization, while the mixing of discharge of groundwater with high Mg²⁺/Ca²⁺ ratios may be responsible for Mg²⁺/Ca²⁺ ratios obviously increasing in surface water, and Mg²⁺/Ca²⁺ ratios in both surface water and groundwater finally tending to a constant. In combination with environmental isotopic analyses, the major mechanism responsible for the water chemistry and its geochemical evolution in the study basin can be revealed as being mainly from the water–rock interaction in karst aquifers, the agricultural irrigation and its infiltration, the mixing of surface water and groundwater and the water movement along faults and joints in the karst basin. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

一次华南暴雨过程的数值模拟和试验   总被引：14，自引：9，他引：5  

张立凤  查石祥 《气象科学》2000,20(2):120-128

本文利用有限区域数值预报模式MM4对一次华南暴雨过程进行了数值模拟和试验.用该模式预报的形势场与实况较一致,预报的暴雨强度、位置也与实况相近.此外由控制试验和敏感性试验可知,该暴雨强度对地形、辐射和下垫面过程比较敏感.  相似文献   

2D acoustic‐elastic coupled waveform inversion in the Laplace domain     

Ho Seuk Bae  Changsoo Shin  Young Ho Cha  Yunseok Choi  Dong‐Joo Min 《Geophysical Prospecting》2010,58(6):997-1010

Although waveform inversion has been intensively studied in an effort to properly delineate the Earth's structures since the early 1980s, most of the time‐ and frequency‐domain waveform inversion algorithms still have critical limitations in their applications to field data. This may be attributed to the highly non‐linear objective function and the unreliable low‐frequency components. To overcome the weaknesses of conventional waveform inversion algorithms, the acoustic Laplace‐domain waveform inversion has been proposed. The Laplace‐domain waveform inversion has been known to provide a long‐wavelength velocity model even for field data, which may be because it employs the zero‐frequency component of the damped wavefield and a well‐behaved logarithmic objective function. However, its applications have been confined to 2D acoustic media. We extend the Laplace‐domain waveform inversion algorithm to a 2D acoustic‐elastic coupled medium, which is encountered in marine exploration environments. In 2D acoustic‐elastic coupled media, the Laplace‐domain pressures behave differently from those of 2D acoustic media, although the overall features are similar to each other. The main differences are that the pressure wavefields for acoustic‐elastic coupled media show negative values even for simple geological structures unlike in acoustic media, when the Laplace damping constant is small and the water depth is shallow. The negative values may result from more complicated wave propagation in elastic media and at fluid‐solid interfaces. Our Laplace‐domain waveform inversion algorithm is also based on the finite‐element method and logarithmic wavefields. To compute gradient direction, we apply the back‐propagation technique. Under the assumption that density is fixed, P‐ and S‐wave velocity models are inverted from the pressure data. We applied our inversion algorithm to the SEG/EAGE salt model and the numerical results showed that the Laplace‐domain waveform inversion successfully recovers the long‐wavelength structures of the P‐ and S‐wave velocity models from the noise‐free data. The models inverted by the Laplace‐domain waveform inversion were able to be successfully used as initial models in the subsequent frequency‐domain waveform inversion, which is performed to describe the short‐wavelength structures of the true models.  相似文献   

Changes in summer TC activity related to thermal differences between land and the sea     

Ki-Seon Choi  Baek-Jo Kim  Yu-Mi Cha  Hae-Dong Kim 《Theoretical and Applied Climatology》2015,121(3-4):479-488

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Impact of lateral boundary conditions on precipitation and temperature extremes over South Korea in the CORDEX regional climate simulation using RegCM4   总被引：1，自引：0，他引：1  

Seok-Geun Oh  Myoung-Seok Suh  Dong-Hyun Cha 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(4):497-509

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