Meso-Scale Hydrologic Modeling for Climate Impact Assessments: A Conceptual and A Regresssion ApproachM.Ozga-ZielinskaauthorJ.BrzezinskiauthorW.FeluchauthorThe paper presents two different approaches to hydrologic modeling for Climate Impact Assessments: A conceptual water balance model and a non-parametric regression model. They both are designed for modeling large-scale river basins (Meso-Scale) at a monthly time step and to accept GCM-based climate scenarios defined as changes in monthly precipitation and temperature. The data requirements for the models are historical, multi-annual series of mean monthly temperature, precipitation, and runoff. These data are used to calibrate the models. GCM data or user-defined sensitivity of climatic variable must be provided for the assessment analyses. The paper describes the theoretical bases of both approaches and presents the results of a comparison of the application of the models to the Vistula River Basin in Poland.1994-05CP-94-010Monograph