Groundwater and Groundwater and SoilSoil

A small introductionA small introductionDipl.-Ing. Walter BerierDipl.-Ing. Walter Berier

DefinitionsDefinitions

GroundwaterGroundwater is water located beneath the ground surface. is water located beneath the ground surface. SoilSoil is the naturally occurring, unconsolidated or loose covering on is the naturally occurring, unconsolidated or loose covering on

the Earth's surface the Earth's surface An An aquiferaquifer is a layer of relatively porous substrate that contains is a layer of relatively porous substrate that contains

and transmits groundwaterand transmits groundwater AquicludeAquiclude is a layer equal to aquifer that is a layer equal to aquifer that notnot contains and contains and

transmits groundwatertransmits groundwater Discharge areaDischarge area is the part of the soil where water flows out is the part of the soil where water flows out RechargeRecharge area is the part of the soil where water flows in area is the part of the soil where water flows in EvaporationEvaporation is water which gases directly into atmosphere is water which gases directly into atmosphere EvatranspirationEvatranspiration is water which gases from plants into is water which gases from plants into

atmosphereatmosphere Confined aquifersConfined aquifers have their limits have their limits Unconfined aquifersUnconfined aquifers do not have limits do not have limits

Soil Horizons:

O and A Organic Matter (Europe around 10 to 30cm, Tropics up to 3m)

B is a mix between organic matter and mineral compartments of the soil (Europe 1 to 10m, Tropics 3 to 50m)

C is a layer out of mineral compartments with different corn sizes (1 to several 100m)

Bed Rock (several kilometre)

Soil is the limiting factor for the amount and Soil is the limiting factor for the amount and the flow of ground waterthe flow of ground water

The smaller the pores the less water in the aquifer.

Different particle/grain sizes make soil a good filter.

For aquifer calculation a particle size analysis is required.

There are only models because the reality is heterogenic.

Result of a particle size analysis

2 to 40mm Gravel

>40mm Stones

0.63 to 2mm Sand

0.001 to 0.063mm Silt

<0.002mm Clay

The hydraulic gradient gives a number on how strong soil can elevate water up

Not all the water in the pores is free to flow (molecular attraction)

WaterWater DataData

Density is 1000g/dmDensity is 1000g/dm3 3 (1 litre = 1 kg)(1 litre = 1 kg) Highest density with 4 degrees (usually frozen)Highest density with 4 degrees (usually frozen) Water is the only molecule which exists in nature as solid, gas and Water is the only molecule which exists in nature as solid, gas and

fluidfluid Pressure only depends on height of the water columnPressure only depends on height of the water column Usual pH of water is 7 (below alkali and upper acid)Usual pH of water is 7 (below alkali and upper acid) Only approx. 0.03 % of all water on earth is adequate available Only approx. 0.03 % of all water on earth is adequate available

drinking water (river and ground water)drinking water (river and ground water) 83.51% sea water, not available groundwater 15.45%, polar ice 83.51% sea water, not available groundwater 15.45%, polar ice

1%, atmosphere 0.0008 %1%, atmosphere 0.0008 % One big tree has Evatranspiration of 100 to 200 l/dOne big tree has Evatranspiration of 100 to 200 l/d Average water use Cambodia 30 l/dAverage water use Cambodia 30 l/d Average water use Germany 170 l/dAverage water use Germany 170 l/d The production of 1 kg rice requires 2000 to 3000 litre of waterThe production of 1 kg rice requires 2000 to 3000 litre of water

Small Scale Water CycleSmall Scale Water Cycle

•It is possible to define the groundwater flow if there are three wells nearby (calculation model available but a little complicated).

•How high soil can lift water depends on several parameters e.g. corn sizes and material and is different from soil to soil

The ground water level reflects the morphology of the surface The ground water level reflects the morphology of the surface depending on soil factors e.g. corn sizedepending on soil factors e.g. corn size

Wells:Wells:

Dug Well (0 to 100m)

Tube (drill) well (several hundred meters)

For water layers which are thin but the area wide extended.

Drain Pipe Well

For large systems to provide a larger community or a city with sufficient adequate water!!

Horizontal filter well

Fractures in the aquifer causes the groundwater to drain. In the upper case the well is dry because there is no fracture where the water can flow.

Air holes in the ground fill up with water and can deliver a very limited well.

Well construction feasibility To-Well construction feasibility To-do List:do List:

Check morphology (recharge and discharge area)Check morphology (recharge and discharge area) Find nearby wells for monitoring of depth (Find nearby wells for monitoring of depth ( Talk to people if the wells run dry throughout the yearTalk to people if the wells run dry throughout the year Find nearby ponds (even dry) for soil layer visibility Find nearby ponds (even dry) for soil layer visibility

(ponds are usually a mirror of the nearby aquifer)(ponds are usually a mirror of the nearby aquifer)

Please note that all what can be done is an approach. Please note that all what can be done is an approach. Whenever you start digging you will find reality!!Whenever you start digging you will find reality!!

Testing of Well YieldTesting of Well Yield

Requirements: Requirements: Distance measuring instrument (laser or meter)Distance measuring instrument (laser or meter) Stopwatches (should be 2)Stopwatches (should be 2) Bucket with scale (min. 20 litres)Bucket with scale (min. 20 litres) Water Pump including power supplyWater Pump including power supply

Procedure:Procedure:

Step 1: Measure difference between water surface and Step 1: Measure difference between water surface and soil surfacesoil surface

Step 2: Find out water flow of the pump by using the Step 2: Find out water flow of the pump by using the bucket and the stop watch (e.g.20 litres in 5 seconds bucket and the stop watch (e.g.20 litres in 5 seconds results in 20/5 equal to 4 l/s) Do not pump the water results in 20/5 equal to 4 l/s) Do not pump the water out of the well you want to test.out of the well you want to test.

Step 3: Pump out water from the well you want to test Step 3: Pump out water from the well you want to test measuring time (e.g. you pump 2 minutes you can measuring time (e.g. you pump 2 minutes you can calculate 120 seconds time 4 l/s equal 480 litres)calculate 120 seconds time 4 l/s equal 480 litres)

Step 3: Measure the time until the water level is same as Step 3: Measure the time until the water level is same as before e.g. 20 minutes for 480 litres results in 480/20 is before e.g. 20 minutes for 480 litres results in 480/20 is 24 l/min or 0.4 l/s.24 l/min or 0.4 l/s.

The well provides:The well provides: 0.4 l/s0.4 l/s 24 l/min24 l/min 1440 l/h1440 l/h 34.560 l/d equal to 34 m34.560 l/d equal to 34 m33/d/d

This well could provide water for This well could provide water for 864 864 peoplepeople if you calculate 40 litres per if you calculate 40 litres per capita per day!!!!!!!capita per day!!!!!!!