Describes the elements required to capture groundwater flow information. OGC WaterML 2.2 Part 4 - GroundWaterML 2 is an OGC Standard. Copyright (c) 2016 Open Geospatial Consortium. To obtain additional rights of use, visit http://www.opengeospatial.org/legal/ . Fluid added to an aquifer by various means such as precipitation, injection, etc. Process by which the water enters or exits a hydrogeologic unit or a void, or flows within a unit or a void. Can flow from/to other natural or man-made features such as rivers, filtration stations, etc. The regularity of flow occurrence, e.g. ephemeral, intermittent, perennial, seasonal. After http://inspire.ec.europa.eu/codeList/WaterPersistenceValue/ (INSPIRE 2013). The process causing the flow, e.g. evapotranspiration, evaporation, transpiration, runoff, baseflow, pumping, infiltration, injection, etc. Refers to the duration, instant or interval of the flow (actual time, not observation time). E.g. "yearly", "summer", "2009" or "2009-2011". Measure of water volume per unit of time. Measure of water quantity per time period with uom. Fluid flow between features through an interface, exiting one feature and entering another. Features into which fluid is flowing are usually units, voids, or fluid bodies, but can be natural surface water features such as rivers or lakes, or even man-made features such as dams or canals. Likewise for features where water is exiting. The fluid body into which water is flowing. The feature into which water is flowing. The feature that denotes the interface between, for example, the groundwater and surface, such as a well, spring, seep, etc., or between two aquifers. The location at which water is being transferred from one one feature into another. The fluid body from which water is flowing. The feature from which water is flowing. Fluid flow within a feature such as a unit, void, groundwater body, or even a man-made feature such as a conduit of some kind. The fluid body that is flowing. The entity in which the groundwater is flowing. Typically a unit, void, or groundwater body, but also be a man-made feature such as some conduit. The location where groundwater is flowing within a feature. An outflow of fluid from a container such as an aquifer, watershed, pipe, etc. An accounting of the water input and output of a hydrogeologic unit, at a particular point in time, with a description of inflows and outflows. Final quantity (sum) of the budget. If recharge = discharge, the sum is 0. Discharge (outflows) considered in the budget. Recharge (inflows) considered by the budget. Validity time of this budget (eg, 2010).