1. Groundwater and Soil A small introduction Dipl.-Ing. Walter Berier

2. Definitions Definitions  Groundwater is water located beneath the ground surface.  Soil is the naturally occurring, unconsolidated or loose covering on the Earth's surface  An aquifer is a layer of relatively porous substrate that contains and transmits groundwater  Aquiclude is a layer equal to aquifer that not contains and transmits groundwater  Discharge area is the part of the soil where water flows out  Recharge area is the part of the soil where water flows in  Evaporation is water which gases directly into atmosphere  Evatranspiration is water which gases from plants into atmosphere  Confined aquifers have their limits  Unconfined aquifers do not have limits

3. 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)

4. Soil is the limiting factor for the amount and the 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.

5. 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

6. 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)

7. Water Data  Density is 1000g/dm 3 (1 litre = 1 kg)  Highest density with 4 degrees (usually frozen)  Water is the only molecule which exists in nature as solid, gas and fluid  Pressure only depends on height of the water column  Usual pH of water is 7 (below alkali and upper acid)  Only approx. 0.03 % of all water on earth is adequate available drinking water (river and ground water)  83.51% sea water, not available groundwater 15.45%, polar ice 1%, atmosphere 0.0008 %  One big tree has Evatranspiration of 100 to 200 l/d  Average water use Cambodia 30 l/d  Average water use Germany 170 l/d  The production of 1 kg rice requires 2000 to 3000 litre of water

9. Small Scale Water Cycle

11. 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

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

13. Wells: Dug Well (0 to 100m) Tube (drill) well (several hundred meters)

14. For water layers which are thin but the area wide extended. Drain Pipe Well

15. For large systems to provide a larger community or a city with sufficient adequate water!! Horizontal filter well

16. 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.

17. Well construction feasibility To-do List:  Check morphology (recharge and discharge area)  Find nearby wells for monitoring of depth (  Talk to people if the wells run dry throughout the year  Find nearby ponds (even dry) for soil layer visibility (ponds are usually a mirror of the nearby aquifer) Please note that all what can be done is an approach. Whenever you start digging you will find reality!!

18. Testing of Well Yield Requirements:  Distance measuring instrument (laser or meter)  Stopwatches (should be 2)  Bucket with scale (min. 20 litres)  Water Pump including power supply

19. Procedure: Step 1: Measure difference between water surface and soil surface Step 2: Find out water flow of the pump by using the 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 out of 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 calculate 120 seconds time 4 l/s equal 480 litres) 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 24 l/min or 0.4 l/s.

20. The well provides:  0.4 l/s  24 l/min  1440 l/h  34.560 l/d equal to 34 m 3 /d This well could provide water for 864 people if you calculate 40 litres per capita per day!!!!!!!