UNDERSTANDING GROUND WATER_Orientation.pptx

UNDERSTANDING GROUND WATER_Orientation

1. Understanding Ground Water & VES Test by Sri Dolamani Sahu , Deputy Director Geology DIRECTORATE OF GWD ODISHA

2. DISTRIBUTION OF WATER ON EARH Ocean Water: 97 % Glaciers and Other Ice: 2.15 % Ground Water: 0.61 % Fresh Water Lakes : 0.009 % Inland Seas : 0.008 % Soil Moisture : 0.005% Atmosphere: 0.001% Rivers: 0.0001 %

3. Out of sweet water only 11% ground water we can use, available within 800mtr depth

4. Understanding Ground Water What is Ground Water? How Does Water Get Into The Ground? Where does it stay and how it move: Aquifer? What happens when ground water is pumped?

5. WATER CYCLE: EARTHS WATER IS ALWAYS IN MOVEMENT AND ALWAYS CHANGING STATES FROM LIQUID TO VAPOUR TO ICE AND BACK AGAIN

6. WHAT IS GROUND WATER GROUND WATER IS PART OF THE NATURAL WATER CYCLE. SOME PART OF THE PRECIPITATION(RAINFALL) THAT LANDS ON THE GROUND SURFACE INFILTRATES IN TO THE SUB-SURFACE. THE PART THAT CONTINUES DOWNWARD THROUGH THE SOIL UNTIL IT REACHES ROCK MATERIAL THAT IS SATURATED IS GROUND WATER

7. WHERE DOES IT STAY AND HOW IT MOVE GROUND WATER EXIST BENEATH THE EARTH’S SURFACE IN ROCKS AND SOIL PORE SPACES ROCKS ARE HAVING FRACTURES WHEN FRACTURES ARE INTERCONNECTED AND WHEN FRACTURES ARE SUFFICIENT, STORAGE QUANTITY IS MORE. WHEN THE ROCK FORMATION IS POROUS AS WELL AS PERMEABLE STORAGE QUANTITY IS MORE

8. FACTORS RESPONSIBLE FOR EXISTENCE OF GROUND WATER TWO IMPORTANT FACTORS CONTROLS QUANTITY OF GROUND WATER ONE IS GRAVITY WHICH PULLS WATER TO SEEP INTO THE GROUND SECOND FACTOR IS THE ROCK FORMATION UNDERNEATH

9. AQUIFER THE ROCK FORMATION WHICH IS POROUS AND PERMEABLE FROM WHERE WE GET SUFFICIENT QUANTITY OF WATER IS CALLED AS AQUIFER A SATURATED FORMATION BUT RELATIVELY IMPERMEABLE IS KNOWN AS AQUICLUDE , HERE WE CAN GET FEW QUANTITY OF WATER EXAMPLE: CLAY

10. A RELATIVELY IMPERMEABLE FORMATION NEITHER CONTAINING NOR TRANSMITTING WATER CALLED AS AQUIFUSE EXAMPLE: HARD GRANITE A SATURATED BUT POORLY PERMEABLE FORMATION KNOWN AS AQUITARD EXAMPLE: SANDY CLAY

11. Leaky Aquifer : In some locations the separating layers between the deep aquifers and the shallower water table aquifer are not completely impermeable, with the result that draft from such aquifers causes some lowering of the water table. Such aquifers are called leaky confined aquifers. Perched Water : Some times a quantity of Ground Water is held above an impervious stratum, and is not connected with the main water table. Such water table is called a perched water table.

12. Connate Water :It is sea water that occurs in some sedimentary formations below the water table. Such water is found in heaved up sedimentary marine deposits(Geosyncline formations) where it has not yet been washed away by fresh water flows.

13. FRACTURED ROCK FORMATION

14. POROUS AND PERMEABLE FORMATION

15. POROSITY POROSITY IS THE AMOUNT OF PORE SPACES WITHIN A GIVEN MATERIAL IN A SOIL OR ROCK THE POROSITY(EMPTY SPACE) EXISTS BETWEEN THE GRAINS OF MINERALS. IN A MATERIAL LIKE GRAVEL THE GRAINS ARE LARGE AND THERE IS LOTS OF EMPTY SPACE BETWEEN THEM. IN SOILS LIKE CLAY THE EMPTY SPACE IS LESS , POROCITY IS MUCH LESS

16. PERMEABILITY PERMEABILITY IS ANOTHER PROERTY OF THE MATERIALS THAT CLOSELY RELATED TO POROSITY. PERMEABILITY REFERS TO HOW CONNECTED PORE SPACES ARE TO ONE ANOTHER. IF THE MATERIAL HAS HIGH PERMEABILITY THEN PORE SPACES ARE CONNECTED TO ONE ANOTHER ALLOWING WATER TO FLOW FROM ONE PORE SPACE TO ANOTHER EASILY

17. AQUIFER AGAIN AN AQUIFER IS A TERM FOR A TYPE OF SOIL OR ROCK THAT CAN HOLD AND TRANSFER WATER THAT IS COMPLETELY SATURATED WITH WATER. THAT MEANS THAT ALL IT IS SIMPLY A LAYER OF SOIL OR ROCK THAT HAS A REASONABLY HIGH POROSITY AND PERMEABILITY THAT ALLOWS IT TO CONTAIN WATER AND TRANSFER IT FROM PORE TO PORE QUICKLY AND ALL THE PORE SPACES FILLED WITH WATER

18. WATER TABLE THE UPPER BOUNDARY OF THE SATURATED ZONE(AQUIFER) IS WATER TABLE THE UNSATURATED ZONE ABOVE THE WATER TABLE STILL CONTAINS WATER (AFTER ALL, PLANTS’ ROOTS LIVE IN THIS AREA) BUT IT IS NOT TOTALLY SATURATED WITH WATER. THE UNSATURATED ZONE ABOVE THE WATER TABLE ALSO KNOWN AS VADOSE ZONE

19. WHAT HAPPENS WHEN GROUND WATER IS PUMPED WHEN A WELL IS PUMPED WATER LEVEL OF THE WELL WILL GO DOWN, IT WILL RECUPE AFTER SOME TIME WHICH DEPENDS ON THE TYPE OF AQUIFER. PUMPING TOO MUCH WATER TOO FAST DRAWS DOWN THE WATER TABLE AND EVEN CAUSE YOUR NEIGHBOUR’S WELL TO RUN DRY IF YOU BOTH ARE PUMPING FROM THE SAME AQUIFER

20. CONE OF DEPRESSION A DEPRESSION IN THE GROUND WATER TABLE OCCURS WHEN PUMPED FROM A WELL. THE WATER TABLE OF THE AQUIFER LOWERS DOWN NEAR THE WELL. THIS AREA IS KNOWN AS CONE OF DEPRESSION. THE LAND AREA ABOVE A CONE OF DEPRESSION IS KNOWN AS AREA OF INFLUENCE. GROUND WATER FLOWS TOWARDS THE WELL INTO THE CONE OF DEPRESSION WHICH CAN CHANGE THE NATURAL DIRECTION OF GROUND WATER FLOW WITHIN THE AREA OF INFLUENCE AROUND THE WELL

21. CONE OF DEPRESSION & AREA OF INFLUENCE

22. WELL INTERFERENCE IF THE CONES OF DEPRESSION FOR TWO OR MORE WELLS OVERLAP, THERE IS SAID TO BE WELL INTERFERENCE. THIS INTERFERENCE REDUCES THE WATER AVAILABLE TO EACH OF THE WELLS.

23. WELL INTERFERENCE

24. INDUCED RECHARGE THE CONE OF DEPRESSION FROM A WELL MIGHT EXTEND TO A NEARBY STREAM OR LAKE. THIS LOWERS THE WATER TABLE BELOW THE STREAM OR LAKE LEVEL. AS A RESULT THE STREAM OR LAKE BEGINS TO LOSE WATER TO THE GROUND WATER AQUIFER NEAR THE WELL. THIS IS KNOWN AS INDUCED RECHARGE.

25. INDUCED RECHARGE

26. GROUND WATER FLOW/ MOVEMENT OF GROUND WATER IN HYDROGEOLOGY, GROUND WATER FLOW IS DEFINED AS THE “ PART OF STREAM FLOW THAT HAS INFILTRATED THE GROUND, ENTERED THE PHREATIC ZONE, AND HAS BEEN DISCHARGED INTO A STREAM CHANNEL OR SPRINGS; AND SEEPAGE WATER”

27. GROUND WATER FLOW GROUND WATER FLOWS UNDERGROUND IN RESPONSE TO ELEVATION DIFFERENCES (DOWNWARDS) AND PRESSURE DIFFERENCES (FROM AREAS OF HIGH PRESSURE TO AREAS OF LOW PRESSURE). NEAR THE WATER TABLE THIS MEANS THAT GROUND WATER USUALLY FLOWS DOWNHILL, i.e. FROM HIGHER LEVEL TO A LOWER LEVEL, JUST AS IT WOULD ON THE SURFACE

28. GROUND WATER FLOW

29. GROUND WATER FLOW WATER MOVES UNDERGROUND DOWNWARDS AND SIDEWAYS, IN GREAT QUANTITIES, DUE TO GRAVITY AND PRESSURE. EVENTUALLY IT EMERGES BACK TO THE LAND SURFACE, INTO RIVERS, AND INTO THE OCEANS TO KEEP THE WATER CYCLE GOING

30. HYDROLOGICAL CYCLE & GROUND WATER FLOW

31. MOVEMENT OF GROUND WATER

32. HOW GROUND WATER POLLUTES GROUND WATER POLLUTION CAN BE CAUSED BY CHEMICAL SPILLS FROM COMMERCIAL OR INDUSTRIAL OPERATIONS CHEMICAL SPILLS OCCURRING DURING TRANSPORT(e.g. SPILLAGE OF DIESEL FUELS ), ILLEGAL WASTE DUMPING, INFILTRATION FROM URBAN RUNOFF OR MINING A LAYER OF OIL FLOATING ON WATER OR COVERING SHORE LINE OF A BODY OF WATER USUALLY PETROLEUM WHICH HAS LEAKED FROM AN OIL TANKER

33. GROUND WATER POLLUTION

34. GROUND WATER POLLUTION

35. GROUND WATER POLLUTION

36. MAIN CAUSES OF GROUND WATER POLLUTION 1. WASTE :ANY TYPE OF USED WATER IS CALLED WASTE WATER. IT CAN COME FROM OUR HOMES OR BUSINESSES AND INCLUDE WATER FROM SINKS, SHOWERS, TOILETS, AND INDUSTRIAL ACTIVITIES. IT ALSO INCLUDES STORM WATER RUNOFF, WHICH IS WHAT HAPPENS WHEN RAINFALL CARRIES ROAD SALTS AND AUTOMATIVE CHEMICALS FROM ROAD TO WATERWAYS

37. 2. LANDFILLS LANDFILLS ARE NORMALLY DESIGNED TO PROTECT AGAINST CONTAMINANT LEAKAGE. COMPLEX SYSTEMS OF LINERS AND PROTECTIVE LAYERS ARE PUT DOWN BEFORE DUMPING TO PREVENT CONTAMINANTS FROM SEEPING INTO THE GROUND AND CONTAMINATING NATURAL RESOURCES. HOWEVER THESE LINERS ARE NOT PERFECT RESULTING TOXIC LEACHATE AND REACH GROUND WATER THROUGH CRACKS/ HOLES.

38. 3. AIR POLLUTION AIR POLLUTION CAN BE PICKED UP BY THE WATER IN THE ATMOSPHERE TO PRODUCE ACID RAIN WHICH IS A GRAVE PROBLEM FOR GROUND WATER. GROUND WATER IS NOT THE ONLY RESOURCE IN DANGER FROM ACID RAIN, HOWEVER MANY PLANTS AND ANIMALS ARE SENSITIVE TO ACIDS AND MAY EXPERIENCE INCREASED MORTALITY

39. 4. FUELS FUELS ARE ANOTHER SOURCE OF CONTAMINATION THAT CAN GET INTO GROUND WATER SOURCES THROUGH SEVERAL MEANS. WHEN CARS, SHIPS, AIRPLANES, COAL-FIRED POWER PLANTS RELEASE NITROGEN OXIDES INTO THE AIR, WHICH CONTRIBUTE TO THE PRODUCTION OF ACID RAIN. THESE NITROGEN OXIDES DEPOSIT ON LAND AND THROUGH RAINFALL CONTMINATE GROUND WATER

40. 5. SEPTIC SYSTEMS SEPTIC SYSTEMS ARE ONSITE WASTEWATER DISPOSAL SYSTEMS COMMONLY USED BY HOMES AND OFFICES. WHILE PROPERLY BUILT SEPTIC SYSTEMS ARE DESIGNED TO DRAIN HUMAN WASTE AT A HARMLESS CONDITION. BUT POOR DESIGN, LOCATION, MAINTENANCE OR CONSTRUCTION CAN CAUSE THESE SYSTEMS TO LEAK PATHOGENS CONTAMINATING THE SURROUNDING AREA.

41. THIS ISSUE CAN BE PARTICULARLY PROBLEMATIC FOR PEOPLE WHO GET THEIR DRINKING WATER FROM NEARBY PRIVATE WELLS

42. 6. CHEMICALS CHEMICAL CONTAMINANTS COME FROM A VARIETY OF RESIDENTIAL, AGRICULTURAL AND INDUSTRIAL SOURCES. ALLUMINIUM, LEAD , MERCURY, RADIUM AND URANIUM ARE JUST A FEW EXAMPLES OF COMMON WATERBORNE CHEMICAL CONTAMINANTS. RUNOFF FROM INDUSTRIAL & AGRICULTURAL AREAS IS ONE OF THE MOST COMMON WAYS THAT THESE CHEMICALS GET INTO GROUNDWATER

43. 7. PESTICIDES PESTICIDES ARE CHEMICALS APPLIED TO FARM LANDS , GARDENS AND LAWNS THAT ARE MEANT TO CONTROL PEST POPULATIONS. HOWEVER THESE TOXIC CHEMICALS CAN MAKE THEIR WAY INTO GROUND WATER SYSTEMS THROUGH RUNOFF. WHILE NOT ALL PESTICIDES POSE A HEALTH HAZARD TO HUMANS, SOME OF THEM INCREASE THE RISK OF CANCER, INJURE THE EYE AND KIDNEYS.

44. SOLUTIONS OF GROUND WATER POLLUTION LEGISLATION : THERE ARE FEDERAL LAWS IN MOST COUNTRIES THAT HELP IN PROTECTING THE QUALITY OF GROUND WATER PROPER MANAGEMENT OF THE SOURCES OF POLLUTION. THE LANDFILLS SHOULD BE DESIGNED WITH PROPER CLAY AND LEACHATE RECYCLING : MOST LANDFILLS IN VARIOUS COUNTRIES HAVE RECYCLING PLANT NEARBY. THEREFORE, USED PETROLEUM PRODUCTS SHOULD BE TAKEN TO SUCH PLANTS.

45. GEOPHYSICAL METHOD FOR GROUND WATER EXPLORATION It is the scientific measurement of Physical properties of the Earth’s Crust. Geophysics is a subject in itself within the science of Geology The most common practice for Ground Water Exploration is the Electrical Resistivity Method There are two most common electrode arrangements for Resistivity determination are

46. 1. Wenner Arrangement 2. Schlumberger Arrangement

47. Electrical Resistivity method:

48. Format For Field Record VES Study Format

49. USE OF AQUAMETER FOR RESISTIVITY SURVEY For resistivity survey the A quameter makes the use of Five(05) probes. Four of them are hammered into the ground in a straight line about the point of investigation. The fifth one is actually hammered at the point of investigation. The outer probes which are current electrodes are connected electrically to C1 & C2 terminals of the Aquameter .

50. The separation of the current probes decides the depth of penetration of the current. As a thumb rule, the current penetrates upto half the distance between C1 C2 probes. The inner probes which are the potential electrodes are connected to P1 & P2 terminals on the Aquameter . The fifth probe is connected to the CENTRE terminal. The voltage developed across the P1 P2 probes as a result of the current passed is a mesaure of Apparent Resistivity of the formation.

51. VES Curves in Alluvial formation

52. VES Curves in Alluvial formation

53. Curves in Hard rock formation

54. THANK YOU ALL