Hydrological models have become more and more important tools for the management of the water resources. They are used for managements, decision support, forecasting and protection and for many other purposes. Recently hydrological models have found a new role in studies of climate change impacts on water resources. The Dutch Water Board of Utrecht Province management area HDSR (Hoogheemraadschap de Stichtse Rijnlanden) is using several hydrological models for water resources management purposes, subsidence observation and analysing flow system for the entire region. One of these models is a spreadsheet model (black- box model principle) that calculates water balance and mass balance for few chemical components for the polder of Zegveld, which is the study area for this research. The main inputs for the spreadsheet model, like other models, is the meteorological data such as precipitation, evapotranspiration and temperature. Moreover, the area characteristics and the vegetation activities are also part of the inputs parameters. Furthermore, soil physical parameters for the area (dominantly peaty clay) based on the field work lab investigation are used like a basic requirement for any hydrological model. In addition, daily groundwater levels (for shallow and deep aquifers) and discharge are used as indicators of the quality of the simulation results. The results of the spreadsheet model were not satisfactory, and the simulated groundwater level is far away from the observed values. In addition, the simulated discharge values are entirely different from the observed values for the year of 2012. However, the discharge values are doubted by the HDSR and, therefore, they are not used as indications for the simulation results. The data of precipitation and evapotranspiration are calculated using classical methods; such as rain gauges for the precipitation and evaporation pan for the evapotranspiration. From the literature it was found that these methods are not accurate enough as an input data for such a hydrological ...