HYDROLOGY FINALS

Static Water Level

The vertical distance from the center line of the discharge to the water surface in the well when there is no pumping.

Pumping Water Level

The vertical distance from the center line of the discharge to the water surface in the well while pumping. During a pumping test, the pumping water level is the depth of water surface when the amount of water withdrawn from the well and the amount of replenishment of water to the well are equal.

Drawdown

The difference between the static water level and the pumping water level.

Yield of the Well

The volume of water per unit time that could be safely pumped from the well, as determined by a pumping test.

Yield of the Spring

The volume of water per unit time discharged by the spring.

Volumetric Method

this method consists of determining the time required to fill a bucket with water. For more accurate results, the measurement is repeated several times, and the average time of these trials is taken. Note that using a bigger container will improve the accuracy of the measurement.

V-notch Weir Method

A weir is an overflow structure built across an open channel for the purpose of measuring the rate of flow of water. Weirs may be rectangular, trapezoidal or triangular in shape.

The Triangular or V-Notch Weir

is a flow measuring device particularly suited. for small flows. The V-Notch Weir often used in flow measurements is the 90° V-Notch.

Through gravity flow

This is the ideal set-up when the location of the water source is at a considerably higher elevation than the area to be served. The operation cost of a gravity system is very low, as it does not require energy cost.

Through pumping with storage

Water is either (a) pumped to a distribution pipe network, then to consumers, with excess water going to a storage tank, or (b) pumped to a storage tank first, then water is distributed by gravity from the tank to the consumers. The maintenance and operation cost of this system is higher than a gravity system.

Through direct pumping

in this system, water is pumped directly from the source to the distribution system to the consumers. Where capital cost for a reservoir is not affordable at the initial stage of the water system, direct pumping to the distribution is usually resorted to Variable speed or variable frequency drive pumps are most ideal for direct pumping operations, but the capital costs for such equipment are higher than for conventional water pumps

Pressure

is a force applied perpendicular to a body that is in contact with a fluid, in this case, with water. Pressure increases linearly with the depth of water. For water at rest, the variation of pressure over depth is linear.

pressure head

The pressure exerted by a column of water is called.

Head Loss

Shear stress is developed between the water and the pipe wall when water is flowing. The shear stress is the result of friction, and is dependent on the flow rate, the roughness of the pipe, and the length and diameter of the pipe.

Hydraulic Grade Line (HGL)

water in a pressurized pipe possesses three form of energy

Kinetic energy

energy due to the water's movement

Potential energy

energy due to elevation

Pressure energy

energy due to internal pressure

Elevated Reservoir

Reservoirs are constructed in elevated or hilly areas. In case of flat areas, a supporting frame or tower is installed to support the storage tank. This is known as an elevated reservoir. Standpipes are reservoirs with height greater than their diameter.

Ground Level Reservoir

may be made of reinforced concrete pipe, fiber glass, concrete hollow blocks, steel or ferro-cement. These may be single ground level tanks or multiple type tanks.