| Groundwater in karst area is very precious for water resources to sustain basic spring discharge and to satisfy water requirement of industry, agriculture and living. A model for groundwater resources management in Xiaonanhai Spring catchment was developed in this paper, and it is very important for groundwater resources management and ecological and environmental protection in this region.The model was applied in the Xiaonanhai Spring catchment, located in Anyang city of Henan province. Based on the hydrological characteristics of karst groundwater flow, the groundwater numerical model, Visual MODFLOW, was calibrated on the basis of the observation data of meteorology, groundwater level and spring discharges, The numerical model was further verified according to the observation data from 2004 to 2005. The study results show that the model is reliable for groundwater flow simulation, and is able to predict the variations of the groundwater levels and spring discharge in this area.On the basis of the calibrated parameters, the response matrix approach was further used to develop the model for groundwater resources management, which was solved by the simplex method. The maximum pumping rates in wet, normal, dry and extreme dry years for meeting the water requirements and maintaining a basis flux over 3.2m~3/s for Xiaonanhai Spring was determined. This rate is 7470.08×10~4 m~3 in the extreme dry year, 7775.57×10~4m~3 in dry year, 9061.1×10~4m~3 in normal year, and 11888.07×10~4m~3 in wet year. The conclusion is: the groundwater exploitation and recharge amount has reached a balance in the Xiaonanhai Spring catchment under the present condition. Increase of the pumping water and mine discharge should be not allowed. The total water withdrawal from the pumping wells should be less than 7698.64×10~4m~3/a. Increase of pumping water would result in decrease of spring discharge. Maintaining the basic spring discharge during the extraordinary dry year should reduce groundwater withdrawal.
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