Groundwater occurrence, Rock properties affecting groundwater, Soil classification
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The document discusses groundwater occurrence, emphasizing its subsurface distribution and the role of geological formations in its hydrology. It outlines different types of groundwater, such as connate, juvenile, metamorphic, and magmatic water, and introduces various aquifer classifications. Additionally, it examines the vertical distribution of groundwater between zones of aeration and saturation, explaining their characteristics and importance in water retention.
Groundwater occurrence, Rock properties affecting groundwater, Soil classification
- 1. Groundwater Occurrence D. Naresh Kumar Assistant Professor Civil Engineerin Department St. Martin’s Engineering College
- 2. The describe the occurrence of groundwater necessitates a review of where and how groundwater exists; subsurface distribution, in both vertical and areal extents, needs to be considered. The geologic zones important to groundwater must be identified, as well as their structure in terms of water holding and water yielding capabilities. If hydrologic conditions furnish water to the underground zone, the subsurface strata govern its distribution and movement, hence the important role of geology in groundwater hydrology cannot be overemphasized. Springs, hydrothermal phenomena, and water in permanently frozen ground constitute special groundwater occurrences. Groundwater Occurrence
- 3. Almost all groundwater can be thought of as a part of the hydrologic cycle, including surface and atmospheric waters, Relatively minor amounts of groundwater may enter this cycle from other origins Connate water: Water that has been out of contact with the atmosphere for at least an appreciable part of a geologic period is termed connate water. Magmatic water: water derived from magma; where the separation is deep the term plutonic water is applied, while volcanic water designates water from relatively shallow depths Origin and Age of Groundwater
- 4. Juvenile water: New water of magmatic or cosmic origin that has not previously been a part of the hydrosphere is referred to as juvenile water. Metamorphic water: Water that is or has been associated with rocks during their metamorphism The residence time of water underground has always been always been a topic of considerable speculation. But with the advent of radioisotopes, determinations of the age of groundwater have become possible. Hydrogen-3(Tritium) and carbon-14 are the two isotopes that have proved most useful. Tritium with a half life of 12.33 years is produced in the upper atmosphere by cosmic radiation.
- 5. Content itself is what the end-user derives value from also can refer to the information provided through the medium, the way in which Content A • Diagram illustrating relationships of genetic types of water
- 6. Rock properties affecting groundwater Aquifers An aquifers may be defined as a formation that contains sufficient saturated permeable material to yield significant quantities of water to wells and springs. Aquiclude- A saturated but relatively impermeable material that does not yield appreciable quantities of water to wells; clay is an example Aquifuge- A relatively impermeable formation neither containing nor transmitting water – granite Aquitard- A saturated but poorly permeable stratum that impedes groundwater movement and does not yield water freely to wells, that may transmit appreciable water to or from adjacent aquifers and where sufficient thick, may constitute an important groundwater storage zone – sandy clay
- 7. • Those portions of a rock or soil not occupied by solid mineral matter can be occupied by groundwater. These spaces are known as voids, interstices, pores, or pore space. Because interstices serve as water conduits. • Where Vv is the volume of interstices, Vs is the volume of solids, and V is the total volume . Porosity
- 9. Soil Classification • Unconsolidated geologic materials are normally classified according to their size and distribution.
- 10. Vertical distribution of groundwater • The subsurface occurrence of groundwater may be divided into zones of aeration and saturation. The zone of aeration consists of interstices occupied partially by water and partially by air. In the zone of saturation, all interstices are filled with water under hydrostatic pressure. On most of the land masses of the earth, a single zone of aeration overlies a single zones of saturation and extends upward to the ground surface
- 11. Zone of Saturation • In the zone of saturation, groundwater fills all of the interstices, hence the effective porosity provides a direct measures of the water contained per unit volume. A portion of the water can be removed from subsurface strata by drainage or by pumping of a well. • Specific retention • The specific retention S, of a soil or rock is the ratio of the water it will retain after saturation against the force of gravity to its own volume. Thus • Where wr is the volume occupied by retained water and Vt is the bulk volume of the soil or rock.
- 12. Specific Yield