Developed in 2013 at the GIPSA-lab research laboratory, the HEDA (Hydrometeorology Exogenous Data Assimilation) software proposes the calibration procedure for a Snow Water Equivalent (SWE) forecasting model, using Moderate-Resolution Imaging Spectroradiometer (MODIS) multi-temporal snow cover maps and in situ measurements. Three different optimization procedures are implemented using different sets of available in situ measurements. The appropriate optimization method can be selected (Nelder-Mead simplex function minimization, Generalized Pattern Search and Genetic Algorithms) and the corresponding representative optimal coefficients are derived for each of the stations. Further, by combining the selected optimization algorithm and the proposed continuous activation function, the user can obtain spatially varying coefficients characterizing the entire region, using multi-temporal MODIS snow cover binary maps.