| dc.description.abstract | Groundwater is one of the important water resources to supply domestic, industry and agriculture activities. Groundwater and surface water interactions can lead to the changes of water budget and water quality. The understanding of the surface water and groundwater interaction behaviors is critical for the regional water resources management. Efforts have been devoted on the issues of groundwater and surface water interactions by using different approaches and various models. Taking advantages of recent studies in developing groundwater models, the Groundwater - Surface water Flow (GSFLOW) model based on the integrations of the Precipitation Runoff Modeling System (PRMS) and the Modular Groundwater Flow (MODFLOW-2005) model is developed to account for interactions between surface water and groundwater flows. However, the text input formats in MODFLOW-2005 and PRMS has limited the implementation of GSFLOW to practical problems with large-scale domains and complex parameter distributions. The objectives of the study are (1) to evaluate the compatibility of MODFLOW-2005 and MODFLOW-2000 based on Groundwater Modeling System (GMS) interface, and to evaluate suitable cell sizes by four testing cases, including the numbers of cells 20x30x2, 60x90x2, 120x180x2, and 180x270x2, in x, y, and z directions, (2) to validate the groundwater levels between observed data and steady-state simulated results in the northwest area of Ho Chi Minh-Vietnam, (3) to assess head variations, water budgets, and the particular effects of input data in various packages of MODFLOW-2005 for the study site, and (4) to analyze daily variations of storage changes, and effects of PRMS input parameters on soil and unsaturated zones at the study area. The results of the study show that (1) the study can take the advantage of GMS interface to incorporate inputs of MODFLOW-2000 in GMS for MODFLOW-2005 in GSFLOW. The suitable cells size of numerical simulations is 120 rows, 180 columns, and two layers for the study area. (2) In MODFLOW-2005, the volumetric budget of study area is influenced approximately 50 % for input and output storage, and -332.25 m3 for the difference of input and output storages. The head distribution decreases from northwest to southeast with low head values less than 2 m in west, south, and southeast of study area. (3) In PRMS, similar variation of soil and unsaturated zonal storages are obtained. The soil and unsaturated zonal storages are 50.35 % and 50.04 % for input storage, 49.65 % and 49.96 % for output storage, and 3.34 m3 and 1379.44 m3 for storage change, respectively. The alterations of runoff and infiltration parameters increase up to 6.89 times of storage changes (23.02 m3) in soil zone, and the changes of soil zone parameters decrease down to 0.47 times of storage changes (652.37 m3) in the unsaturated zone. | en_US |