In hydrology, discharge is the volume rate of water flow, including any suspended solids (e.g. sediment), dissolved chemicals (e.g. CaCO_3(aq)), or biologic material (e.g. diatoms), which is transported through a given cross-sectional area. Frequently, other terms synonymous with discharge are used to describe the volumetric flow rate of water and are typically discipline dependent. For example, a fluvial hydrologist studying natural river systems may define discharge as streamflow, whereas an engineer operating a reservoir system might define discharge as outflow, which is contrasted with inflow.