水力学是研究液体机械相关特性的学科，是流体力学的一部份。

早期研究水力学的包括古希腊的发明家希罗（Hero of Alexandria）及克特西比乌斯(Ctesibius)，不过他们对于实际应用的研究较少。古代居住在斯里兰卡的僧伽罗人就已经开始应用水力学的原理。在二千年前他们就利用 valve tower(valve pit ??)来调节水流。在一世纪时就已经完成几个大型的灌溉系统。当时的斯里兰卡也有提供家庭园艺及农业的水力系统、也有相关的排水系统、水土保持，水力也用在装饰、娱乐及冷却系统中。

Benedetto Castelli是近代水力学奠基人之一，他是伽利略的学生。

Hydraulics is a topic in applied science and engineering dealing with the mechanical properties of liquids or fluids. At a very basic level, hydraulics is the liquid version of pneumatics. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the engineering uses of fluid properties. In fluid power, hydraulics are used for the generation, control, and transmission of power by the use of pressurized liquids. Hydraulic topics range through some part of science and most of engineering modules, and cover concepts such as pipe flow, dam design, fluidics and fluid control circuitry, pumps, turbines, hydropower, computational fluid dynamics, flow measurement, river channel behaviour and erosion.