In this book methods of the annual rainfall, actual evapotranspiration, potential evapotranspiration, recharge (soil moisture surplus) and the change in groundwater flow estimation are included.Some research outputs are also included. The hydrochemistry study shows that there is spatial variation in the chemical and physical properties'' of water. TDS, temperature, and EC increase from highland areas to low land areas. Based on the analytical results in the project area in North Western Ethiopia, all water types are HCO3 except the thermal spring which is HCO3-Cl type and Ca-Ma and Na are the major cations. From groundwater point of view four general potential zones are delineated by combining t lithology, geomorphology, and soil maps of area. These zones are categorized as high, moderately, slightly and least potential zones.