Recent experience at Hoe Creek and Hanna underscores the importance of the hydrological properties of the coal seam and adjacent confining layers to the gasification process. Permeability of the confining layers governs water influx and therefore gas quality. Directional permeability and the ratio of horizontal to vertical permeability and vertical stratification will control linking and the orderly progress of forward gasification. Practical hydrologic testing methods are outlined for obtaining directional permeability, the ratio of horizontal to vertical permeability, permeability of confining layers, along with compressibility, well efficiency and the in-situ fracture distribution. Vertical stratification is obtained using a new downhole flow tool sensitive to flow rates as .1 gpm. Field examples are given to illustrate the required instrumentation and derived parameters.