3Kita sudah bincang mengenai MineralBatuanTanahNow AIR pulak
4Objectives Memahami perbezaan bidang hidrogeologi dgn hidrologi Meninjau sumber air dan kitar airMemahami konsep asas: keliangan (porosity), ketelapan (permeability), akuifer, akuitard, akuiklud.Memahami konsep paras air dan faktor yg mengawal kedudukannyaDescribe the character and behaviour of groundwater in various settingsDiscuss environmental problems related to groundwater.
5Hydrogeology vs hydrology Sama saja dalam segala segiKalau beza sikit sangat
6Groundwater as an important resource for Drinking water (life)Erosion (subterranean caverns) (geological processes)Equalizer of stream flow (geological processes)Agriculture
7Water holding capabilities of rock Consider properties of rock for storage & transport of water:Porosity - percentage of rock's volume that is openingsPermeability - ability of rock to transmit a fluidAquifer - Rock that is permeable, able to store and transport water (examples)Aquitard - Rock that is impermeable, acts to hinder or prevent water movement (examples)
8RESERVOIRAIRInfinite tapi pastiLuas tetapi terhad
10Hydrologic cycle Powered by solar energy and gravity Evaporation and precipitationContinuous recycling of waterWhere does water go that falls on the land?Runoff (air larian)InfiltrationEvaporation (penyejatan)Temporary storage as snow and iceTemp. storage in lakesTemp storage in plants (evapotranspiration) and animalsChem reactions with rocks and minerals
12Source of additional water? volcanism (steam) Volcanism also causes melting of snow caps and mudflows as meltwater mixes with ash
13Distribution of water on the Earth Total = 326 million cubic milesPercentages97.2% oceans2.15% ice caps and glaciers.65% lakes, streams, groundwater, atmosphere(bandingkan dgn slaid no 5)
14Hydrologic Cycle (in greater details) A. Division of water on Earth97.2% in oceans2.15% in glaciers (largest source of fresh (non- saline) water on Earth)0.62% in groundwater (underground aquifers)0.017% in lakes0.005% in soil moisture0.001% in atmosphere0.0001% in stream channels
15Water budget Of all the water that comes out as rain on land: 50% is evaporated and transpired by plants30% goes into runoff, eventually reaching the ocean20% goes into groundwater
16Porosity and Permeability Dua ciri yg penting yg ada pada batuan dan tanah
17Porosity = volume of pores/total volume Porosity (keliangan) is the amount of pore space in a rock (the spaces between the grains)Porosity = volume of pores/total volume
19Tazkirah/peringatanTahukah anda semua jenis batuan mendak, igneus dan metamorfik?Tahukah anda ciri2 asas pada ketiga-tiga jenis batuan tersebut? (struktur kimia, sifat fizik dan kimia, proses kejadiannya/pembentukkannya)
20Porosity is independent of grain size. Porosity depends on:Sorting of the grains (or uniformity of grain size) Are the grains all the same size (well sorted), or are a variety of grain sizes present, with finer grains filling the spaces between the larger grains (poorly sorted)?Shape of the grainsPacking and arrangement of grains. Cubic packing. Porosity = 47.64% Rhombohedral packing. Porosity = 25.95%
21sortingHigh energy environmentLow energy environment
25Pengelasan batuan mendak 1 Terrigenous (detrital or clastic) – bumi/benuaConglomerate or BrecciaSandstoneSiltstoneShaleclaystone2 Chemical/biochemicalEvaporitesCarbonate sedimentary rocks (limestones and dolostone)Siliceous sedimentary rocks3 Organic (coals)Other – ironstonesPOROSITY?Ada/tak adaRendah/tinggi
26Permeability (ketelapan) is the ease with which fluids flow through a rock or sediment A rock is permeable if fluids pass through it, and impermeable if fluid flow through the rock is negligible
27Definition of permeability Rujukan: Rock Slope Engineeringby Hoek and Bray (1979)
28Permeability depends on: Grain size Coarser-grained sediments are more permeable than fine-grained sediments because the pores between the grains are larger.SortingGrain shapePacking (controls pore size)
29What are some examples of a rock with high permeability? What are some examples of a rock with low permeability?JAWAPAN ANDA?
36AQUIFER, AQUICLUDES, WATER TABLE, UNCONFINED, CONFINED AND PERCHED WATERS
37Aquifers and aquicludes An aquifer is a water-bearing rock. Aquifers have high porosity and high permeability.Examples of rock types that could be aquifers?Aquicludes are water-excluding rocks. They have little or no porosity or permeability.Examples of rock types that could be aquicludes?
43The Water Table (Paras air) When it rains, some of the water percolates or soaks into the ground. We call this infiltration. Some of the water is held in the soil because it clings to the soil particles because of molecular attraction. It may evaporate from the soil or be used by plants (zone of aeration, also called the vadose zone). Both air and water occupy the pores spaces.
44Excess water penetrates downward until it reaches the water table Excess water penetrates downward until it reaches the water table. Below this point, all of the pore spaces are filled with water (zone of saturation (ZON TEPU), also called the phreatic zone).
45The water table is the top of the zone of saturation. The water table is not flat. It mimics the topography, but is more subdued. It stands somewhat higher under hills, and lower under valleys.
49Where the water table intersects (or lies above) the ground surface, springs, lakes, swamps, or rivers are present. In humid areas, groundwater movement supplies a flow of water to a stream or river.If a well is drilled, the waterlevel in the well is at the water table.
50The position of the water table may fluctuate with droughts. If water is withdrawn from a well, the water table is lowered in the immediate vicinity of the well. The lowered surface of the water table around a well forms a conical depression in the water table. It is called the cone of depression.If significant quantities of water are withdrawn from a well, the cone of depression may be so large that it affects the water level of other wells nearby.
51Water table & groundwater flow ProcessesRecharge-precipitation and infiltrationDischarge-rivers, runoff, pumpingRelation to topographyRelation to seasonality