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Wang K.-L.,China Agricultural University | Wang K.-L.,Chinese International center for Research and Training in Agriculture | Huang G.-H.,China Agricultural University | Huang G.-H.,Chinese International center for Research and Training in Agriculture
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2010

For the highly heterogeneous media, the logarithm hydraulic conductivity (lnK) is considered as a non-stationary random field with its increments following a Levy-stable distribution. In this paper, the successive random additional (SRA) algorithm is used to produce the lnK field of the aquifer based on the Levy-stable distribution. A Monte-Carlo simulation, with which the MODFLOW and MT3DMS are used to simulate water flow and contaminant transport respectively, is performed to investigate the impact of highly heterogeneous properties on the spatial moments and macrodispersion of contaminant plume. Results indicate that the Levy index α is mainly responsible for the shape of lnK distribution, while the width parameter C has significant effect on the range of lnK values. As α becomes smaller, the contaminant plume shows more anomalously with a long time tailing part. It is also found that the spread of the contaminant plume increases with the increase of width parameter C, but the centroid position of the plume is basically independent of the values of parameters C and α. The longitudinal macrodispersivity is scale-dependent and increases as a power law function of time. Source

Xu X.,China Agricultural University | Xu X.,Chinese International center for Research and Training in Agriculture | Huang G.,China Agricultural University | Huang G.,Chinese International center for Research and Training in Agriculture | And 3 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2011

Due to the spatial variability of soil hydraulic properties and hydrological factors, field scale models with one-dimensional structure were not applicable to the regional scale modeling. A distributed model, which is named as GSWAP, was developed for simulating soil water flow and salt transport on a regional scale by closely coupling the Soil-Water-Atmosphere-Plant (SWAP) model and ArcInfo. The data of GSWAP can be efficiently pre/post processed based on the strong capabilities of spatial data analysis and processing in ArcInfo. The study area was divided into subunits through the combination of soil type, land use, climate and water table depth conditions. Each subunit was supposed to be an equivalent homogenous system with a set of effective soil hydraulic parameters, which were obtained by using the Genetic Algorithms coupled with SWAP model. Finally, the GSWAP model was applied to the Yonglian Irrigation System, Hetao Irrigation District of Inner Mongolia as a case study. Results showed that the GSWAP model could be efficiently used to simulate the soil water and solute dynamics on a regional scale. Source

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