Hydrological cycle and water budgets

In this chapter, we describe the hydrological cycle and each of its components (pools). The hydrological cycle is important to the transport and cycling of nutrients and energy. Quantifying the various components of the hydrological cycle, referred to as constructing water budget for a defined area, is an important framework for wise and equitable water management. The hydrological cycle has changed as the result of human activity affecting specific components of the water budget and the movement of water between the components. Water budgets are provided for two defined areas: the earth as a whole and the watershed of a small inland lake.

Given a specific area with well-defined boundaries, constructing a water budget consists of quantifying the amount and relationships among inflow, outflow, and change in storage within a defined area of the hydrological cycle, water budgets relevant to inland waters and aquatic ecosystems, and how the hydrological cycle and water budgets have been affected by anthropogenic modifications.