Increased irrigation in the Neishaboor watershed, Iran, during the last few decades has caused serious

groundwater depletion, making the development of comprehensive mitigation strategies and tools increasingly important. In this study, SWAT and MODFLOW were employed to integratively simulate surface-water and groundwater flows. SWAT and MODFLOW were iteratively executed to compute spatial and temporal distributions of hydrologic components. The combined SWATMODFLOW model was calibrated (2000–2010) and validated (2010–2012) based on streamflow, wheat yield, groundwater extraction, and groundwater-level data. This multi-criteria calibration procedure provided greater confidence for the partitioning of water between soil storage, actual evapotranspiration, and aquifer recharge. The SWAT model provided satisfactory predictions of the hydrologic budget for the watershed outlet. It also provided good predictions of irrigated wheat yield and groundwater extraction. The 10-year mean annual recharge rate estimated using the combined model varied greatly, ranging from 0 to 960 mm, with an average of 176 mm. This result showed good agreement with the independently estimated annual recharge rate from an earlier study. The combined model provides a robust tool for the sustainable planning and management of water resources for areas with stressed aquifers where interaction between groundwater and surface water cannot be easily assessed.

Developing an accurate conceptual model is the most important step in the process of a groundwater numerical modeling. Disorganized and limited available data and information, especially in the developing countries, make the preparation of the conceptual model difficult and sometimes cumbersome. In this research, an integrative and comprehensive method is proposed to develop groundwater conceptual model for an unconfined aquifer. The proposed method consists of six steps. A preliminary step (step 0) is aimed at collecting all the available data and information. The output of the first step as “controlling observations” is conceptual model version 00. This step should be rigorously checked due to its critical role in the controlling of final conceptual model. Step 2 determines the aquifer geometry. The output of this step is conceptual model version 01. Step 3 is responsible to determine hydrodynamic properties and its output develops conceptual model version 02. Step 4 evaluates the surface and subsurface interactions and lateral in/out groundwater flows. The output of this step is conceptual model version 03. Step 5 is to integrate the results from other steps and to deliver the final conceptual model version. The accuracy level of the conceptual model and the annual groundwater balance is also determined at this step. The presented groundwater conceptual model procedure was implemented for the Neishaboorplain, Iran. Results showed its .usefulness and practicality in developing the conceptual model for the study area