Define drawdown free#

This method uses a lead weight attached to a steel measuring tape. Wetted tape method is a commonly-used method for measuring water levels up to roughly 90 feet deep.This method obtains water table depth using a pressure gauge and water displacement. Air line method is a convenient and nonintrusive method used to measure water levels that is often used for the repeated testing of wells over 300 feet deep.Current supplied from a small battery flows through the circuit when the tip of the wire is in contact with the surface of the water. This method uses a weight attached to a stranded insulated wire and an ammeter to indicate a closed circuit. Electric sounders are a practical land cost-effective method used to measure well water levels.Acoustic well sounders or echometers are a simple, cost effective, and minimally intrusive tool used to measure subsurface pressures and levels.Transducers are used to measure water levels in groundwater wells, rivers, streams, tanks, open channels and lift stations.Well yield is the volume of water per unit time that is produced by the well from pumping.Water table is the upper level of the zone of saturation, an underground surface in which the soil or rock is permanently saturated with water.Static level is the level of water in the well when no water is being removed from the well by pumping.Specific capacity is the well yield per unit of drawdown.Pumping level is the level of water in the well during pumping.

Define drawdown free#

It is the height of the free surface of water above a given point beneath the surface.

Hydraulic head (or piezometric head) is a specific measurement of the potential of water above a vertical datum.

Groundwater is water located beneath the earth's surface in pores and fractures of soil and rocks.

Cone of depression is a conically-shaped depression that is produced in a water table as a result of pumping water from a well at a given rate.

Aquifer test (or a pumping test) is a field experiment in which a well is pumped at a controlled rate and the aquifer's response (drawdown) is measured in one or more observation wells.

Aquifer is an underground layer of permeable rock or sand, that hold or transmit groundwater below the water table that yield a significant supply of water to a well.

3 Ecological impacts of groundwater drawdown.regional seasonal decline due to discharge in excess of recharge.in response to local, intensive groundwater pumping.interference from a neighbouring pumping bore.The main contributor to groundwater drawdown since the 1960s is over-exploitation of groundwater resources.

A record of hydraulic head, or rate of flow ( discharge), versus time is more generally called a hydrograph (in both groundwater and surface water). Drawdown is often represented in cross-sectional diagrams of aquifers. In either case, drawdown is the change in hydraulic head or water level relative to the initial spatial and temporal conditions of the system. In surface water hydrology and civil engineering, drawdown refers to the lowering of the surface elevation of a body of water, the water table, the piezometric surface, or the water surface of a well, as a result of the withdrawal of water.In subsurface hydrogeology, drawdown is the reduction in hydraulic head observed at a well in an aquifer, typically due to pumping a well as part of an aquifer test or well test.In water-related science and engineering, there are two similar but distinct definitions in use for the word drawdown: JSTOR ( December 2009) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed.įind sources: 'Drawdown' hydrology – news Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.