ABSTRACT
This chapter outlines the hydrological cycle and introduces the concepts of aquifers and permeability. It discusses groundwater temperatures, basic groundwater chemistry and the effect of climate and weather. The hydrological cycle illustrates clearly that precipitation replenishes the groundwater in the voids of the soils and rocks and that gravity flow causes movement of groundwater through the pores or fractures of soil and rock masses, towards rivers and lakes and eventually to the oceans. Understanding the concepts and principles of groundwater flow is a fundamental pre-requisite for success in the design and management of groundwater control systems. The hydrological cycle introduced earlier implies that groundwater is continuously in motion, albeit slowly. The starting point for understanding groundwater flow is permeability. This is a critical parameter for the assessment of how water flows through soil and rocks. The modern understanding of flow of groundwater through permeable ground originates with the research of the French hydraulics engineer, Henri Darcy.
