Hydrosphere: The Earth's Water World PDF

Hydrosphere: The Earth’s Water World Basic Concepts Related to Hydrosphere Basic Concepts Related to Hydrosphere ▫ HYDROSPHERE is the discontinuous layer of water on or near the surface of the Earth. ▫ Hydrosphere includes the liquid and frozen surface waters, groundwater, a...

Hydrosphere: The Earth’s Water World Basic Concepts Related to Hydrosphere Basic Concepts Related to Hydrosphere ▫ HYDROSPHERE is the discontinuous layer of water on or near the surface of the Earth. ▫ Hydrosphere includes the liquid and frozen surface waters, groundwater, and  atmospheric water vapor. 3 Water covers about 71% of the Earth’s surface. 4 Composition of the Earth’s Water Masses Reservoir Volume Percent of (in cubic km) Total Oceans 1, 338, 000, 000 96.5% Ice Caps, Glaciers, 24, 064, 000 1.74% Permanent Snow Ground Ice and Permafrost 300, 000 0.22% Groundwater 23, 400,000 1.69% Lakes 176, 400 0.013% (c) Britannica 5 Composition of the Earth’s Water Masses  Reservoir Volume Percent of (in cubic km) Total Soil Moisture 16, 500 0.001 Atmosphere 12, 900 0.001 Swamp Water 11, 470 0.008 Rivers 2, 120 0.0002 Biota 1, 120 0.0001 (c) Britannica 6  The Hydrologic Cycle What is hydrologic or water cycle? Why is it important to us, human beings? The Hydrologic Cycle ▫ known as water cycle ▫ cycle that involves the continuous circulation of water in the Earth-  atmosphere system ▫ includes many processes, among them are evaporation, condensation, precipitation, transpiration, and run-off 8 9 Evaporation happens when a liquid 1 turns into a gas (water vapor)  2 The Hydrologic Cycle 10  4 Precipitation any liquid or solid water 3 that falls to Earth as a result of condensation in the atmosphere The Hydrologic Cycle 11 The Hydrologic Cycle 12 The Hydrologic Cycle 13 Transpiration process of water vapor 5 being released from plants and soil  6 The Hydrologic Cycle 14  8 Sublimation process by which ice and 7 snow (a solid) changes into vapor without going through the liquid phase The Hydrologic Cycle 15 Groundwater Resources  What is the importance of groundwater? Groundwater Resources ▫ refers to water that is collected in porous layers of underground formation ▫ water found underground in the cracks and spaces in soil, sand and rock ▫ stored in and moves slowly through geologic formations of soil, sand and rocks called AQUIFERS 17 Groundwater Resources ▫ largest potential freshwater source in the hydrologic cycle ▫ generally free of sediment, color,  and disease organisms, although polluted groundwater conditions are considered irreversible ▫ POLLUTION and OVERCONSUMPTION are some of the threats to the quality and quantity of groundwater 18 Groundwater Resources ▫ groundwater accumulation varies from one place to another ▫ Heavy rains or melting snow may cause the water table to rise (RECHARGED). ▫ Heavy pumping of groundwater supplies may cause the water table to fall. ▫ Groundwater is brought to the surface naturally through a spring, or can bedischarged into lakes and streams. 19 Groundwater ▫ It begins as surplus water which infiltrates then percolates downward as gravitational water from zone to capillary  water to zone of aeration – an area that is less saturated and is filled with both air and water. ▫ Water then goes to an area where subsurface water accumulates – known as zone of saturation. ▫ Flooding occurs when the ground below is saturated. 20 Groundwater ▫ The measure of the total pore space in the soil.is called "porosity". It is defined as the ratio of the volume of the voids or pore space divided by the total volume. ▫ The rate at which water flows through the soil is its "permeability". It is related as to how connected the pore spaces are.  21 Groundwater ▫ Saturation zone stores  water in its countless pores and voids. ▫ An aquifer is a term for a type of soil or rock that can hold and transfer water that is completely saturated with water. It has high permeability and porosity. 22 Groundwater ▫ An aquiclude or aquitard is a rock layer that does not conduct water in usable amounts. Aquitard can have high porosity and hold lots of water ▫ However, aquitard’s low permeability unables it to transmit water from pore to pore. Therefore water cannot flow within an aquitard very well. ▫ The upper limit of the water that collects in the zone of saturation is the water table. 23  24 Overuse of Groundwater ▫ As water is pumped from a well, the surrounding water table within an unconfined aquifer may experience drawdown. ▫ Overpumping or groundwater mining – act of pumping aquifers beyond their flow and charge capacity - is becoming common in different parts of the world to sustain their increasing water consumption. 25 Overuse of Groundwater  ▫ Water removal from an aquifer may cause it to lose its internal support, thus leading to a phenomenon known as land subsidence. ▫ Collapsed aquifers may not be rechargeable even if surplus water becomes available. 26  Groundwater: Land Subsidence 27 Overuse of Groundwater ▫ Overpumping of water in coastal areas may result to saltwater/ seawater intrusion. Once contaminated, the aquifer is difficult to reclaim. 28 Groundwater Resources in the Philippines What is the status of groundwater in the Philippines? Groundwater Resources in the Philippines ▫ Based on Master Plan Study on Water Resources Management in 1998, Region II has the highest groundwater potential while Region VII has the lowest groundwater potential. ▫ Annual potential water of the Philippines is 145, 990 million m³,  with 14% of which is groundwater. ▫ extensively used for domestic, industrial, and irrigation purposes 30 Groundwater Resources in the Philippines31 Groundwater Resources in the Philippines ▫ Despite the high annual average rainfall, the geography of the country limits its water storage capacity. ▫ There is an incomplete understanding as to the thickness and extent of Philippine aquifers. 32 Groundwater Resources in Metro Cebu ▫ major source for most of Metro Cebu and the entire province ▫ limited catchment basins for groundwater due to its topography ▫ covers a total area of 180 square kilometers  ▫ groundwater extraction is higher than the recharge 33 (c) Philippine Institute for Development Studies and JICA Report Groundwater Resources in Metro Cebu 34 (c) Philippine Institute for Development Studies and JICA Report The Ocean Basins What are ocean basins? What are the different geological parts of the Earth’s ocean basins? ▫ covers about 71% of the Earth’s surface ▫ place where much of the Earth’s oxygen is produced  (through phytoplankton) 36 Introduction to Oceans  ▫ plays a vital role in controlling both the climate and the weather at the Earth’s surface ▫ absorbs much of the excess carbon dioxide37 Introduction to Oceans  ▫ major source of food 38 Geological Structure of Ocean Basins  ▫ oldest rocks in the ocean were not found in the center, as might be expected, but at the ocean margins ▫ ocean basins form when two plates spread apart and new crust is formed at the mid-ocean ridge ▫ edge of the ocean basin, and generally its deepest part, is the bottom of the continental rise which is also where the oceanic lithospheric plate 39 Depth and Shape of Ocean Basins ▫ deep ocean is nearly as rugged in its bathymetry as the terrain we see on land ▫ undersea mountains are in general longer the valley floors wider and the canyons often deeper than  the equivalent features on land 40 Depth and Shape of Ocean Basins ▫ CONTINENTAL SHELF is the area of seabed around a large landmass where the sea is relatively shallow compared with the open ocean; geologically part of the continental crust. ▫ It is usually less than 150 m deep; most of its sediments are derived from the physical erosion of the land; often has rich fisheries and hydrocarbons41 Depth and Shape of Ocean Basins ▫ CONTINENTAL SLOPE – located between the outer edge of the continental shelf and the deep ocean floor ▫ ABYSSAL PLAIN- flat seafloor area at an abyssal depth (3-6 km) generally adjacent to a continent ▫ SEAMOUNT- undersea mountains of about 1 km higher compared to their surrounding seafloor; biological hotspot that supports a wide array of marine life; considered as a navigational hazard 42  world GREAT CHAGOS BANK (British Indian Ocean ▫ Some seamounts are tall enough to reach the surface as oceanic islands or atolls ▫ Flat-topped seamounts are MAUNA KEA (USA) – tallest mountain in the called GUYOTS. AUSTRALIA-TASMANIA AREA when measured from its underwater base (over 10km) KŌKŌ GUYOT – largest guyot in the world  Territory) – largest atoll in the world 43 Depth and Shape of Ocean Basins ▫ OCEAN RIDGES are continuous submarine mountain chain extending approximately 80,000 km (50,000 miles)  through all the world’s oceans ▫ TRENCHES are the deepest valleys on Earth; they are narrow, steep-sided 44 Physical Properties of the Ocean What are the major elements present in the ocean? Physical Properties of the Ocean Sulfur (as 905 sulfates) Element Concentration in Seawater Calcium 412 (mg/L) Potassium 380 Chloride 19 500 Sodium 10 770 ❑ Seawater is made up principally of sodium chloride and magnesium Magnesium 1 290 sulfate, with significant amounts of potassium, calcium, and bicarbonate. ❑ The chemicals that make up the the sea, and they are involved in salt in seawater were originally a variety of chemical, geological, derived from the chemical and biological reactions as they weathering of rocks of land. reach the sea. ❑ They flow as a dilute solution into (c) Holden (2017) 46 Physical Properties of the  ▫ Although the ratio of Ocean most chemical elements in the seawater is constant over all the world’s oceans, its actual concentration varies on the location and rate of evaporation. ▫ The concentration of salt in the ocean is expressed as parts per thousand (ppt)  or in salinity units. 47 Temperature and Salinity Structure of the Oceans Temperature Structure ▫ The surface of the ocean of the Oceans gains heat by radiation from the Sun, particularly in lower  latitudes, and by conduction and convection from warm air flowing over the waves. ▫ Heat is lost by evaporation, reradiation to space, and by conduction to cold air above. ▫ Water, specially oceans acts as a major storage of the energy of the Sun. 49 Temperature and Salinity Changes in Oceans ▫ water density increases with increasing salinity and decreasing temperature ▫ Thermocline - oceanic water layer in which water temperature decreases rapidly with increasing depth ▫ Halocline - which is the layer where  salinity concentration also rapidly changes. 50 Temperature and Salinity Structure of the Oceans ▫ Pycnocline is the boundary separating two liquid layers of different densities. ▫ Because the pycnocline zone is extremely stable, it acts as a barrier for surface processes. ▫ Water density varies throughout the ocean and the water at the bottom of the ocean is densest. 51 Global Surface Salinity by NASA 52 Global Average Sea Temperature by Earth Observer and National Oceanographic Data Center  53 Global Average Sea Temperature and Salinity by National Oceanographic and Atmospheric Administration  54 Deep Ocean Currents ▫ The large-scale deep circulation of the world’s oceans is not driven by wind but by density variations. ▫ The density of seawater is controlled by its salinity and temperature. The resulting circulation is called the THERMOHALINE CIRCULATION. ▫ When a body of water becomes denser than the water surrounding  it, it sinks. ▫ Water that sinks away into the deep has to be balanced by water upwelling to the surface 55 Deep Ocean Currents ▫ Regions of upwelling are important because the upwelled water contains an abundance of plant nutrients, nitrate and phosphate, which, when they reach the surface layers where there is sufficient light, result in a vast bloom of phytoplankton which in turn sustains major fisheries.  56 Global Ocean Conveyor Belt ▫ The GLOBAL OCEAN CONVEYOR  BELT is a constantly moving system of deep-ocean circulation driven by temperature and salinity. ▫ The ocean conveyor gets its “start” in the Norwegian Sea, where warm water from the Gulf Stream heats the atmosphere in the cold northern latitudes. ▫ This loss of heat to the atmosphere makes the water cooler and denser, causing it to sink to the bottom of the ocean. 57  Global Ocean Conveyor Belt ▫ As more warm water is transported north, the cooler water sinks and moves south to make room for the incoming warm water. ▫ This cold bottom water flows south of the equator all the way down to Antarctica. ▫ Eventually, the cold bottom waters returns to the surface through mixing and wind-driven upwelling, continuing the conveyor belt that encircles the globe. 58 Global Ocean Conveyor Belt ▫ Heat and nutrients move around the world in about a 1000-year cycle. ▫ The heat carried north helps keep the Atlantic ocean warmer in the winter time, which warms the nearby countries as well. 59 60 Global Ocean Conveyor Belt ▫ Global warming may cause sufficient freshwater to be released from the melting of ice in the northern latitudes to slow or even to stop the formation of the North Atlantic Deep Water by reducing salinity to the level where it is insufficiently dense to sink. ▫ This would have a dramatic cooling effect on the climate of north-west Europe. 61 Surface Ocean Currents ▫ The surface currents are driven by the prevailing winds. ▫ The trade winds that blow out of the south-east in the southern hemisphere and out of the north-east in the northern hemisphere drive the Northern and Southern Equatorial Currents, which  move in a westerly direction parallel to the equator. 62 Surface Ocean Currents ▫ These currents are deflected by the continents when they reach the coastal areas. ▫ In addition to the continents deflecting the water, the Coriolis Effect also causes water to deflect to the right in the northern hemisphere and to the left in the southern hemisphere. 63 Surface Ocean Currents ▫ The center of some of the gyres contains large amounts of debris such as plastic which has been carried there by the surface ocean currents after being dumped into the oceans by humans. ▫ Example of this is the GREAT PACIFIC GARBAGE PATCH.64 Garbage Accumulation in World’s Oceans 65 Plastic Pollution Data by University of Oxford  Biological Productivity of Oceans What is the contribution of the oceans to the world’s biological productivity? Biological Productivity ▫ The highest productivity in the oceans occurs in those areas where  the supply of dissolved nutrients is greatest. ▫ The most productive areas of the ocean are the areas of coastal upwelling which have abundant life. ▫ Although most of the life in the oceans are found near the surface, several kinds of flora and fauna also thrive in ocean bottoms, like in hydrothermal vents. 68 Biological Productivity ▫ In all the waters of every ocean, one organism preys on another. ▫ At the base of this food chain further explanation of food chains) are the phytoplankton, the primary producers, while at the top of the pyramid are the carnivores: sharks, tuna and of course now also humans. 69 Global Plankton Range  70 Effects of Climate Change on Oceans What is the effect of climate change to the world’s oceans? Effects of Climate Change to World’s Oceans  ▫ The major global temperature change is in the oceans not on land: 93% of the additional heat since the 1970s has been absorbed by the oceans, leading to an average increase of almost 2°C to global surface temperature of world’s oceans. 72 Effects of Climate Change to World’s Oceans  ▫ Increasing ocean temperatures affect marine species and ecosystems. ▫ Rising temperatures cause coral bleaching and the loss of breeding grounds for marine fishes and mammals. 73  74 Effects of Climate Change to World’s Oceans ▫ Rising ocean temperatures also affect the benefits humans derive from the ocean – threatening food security, increasing the prevalence of diseases and  causing more extreme weather events and the loss of coastal protection. 75 Effects of Climate Change to World’s Oceans ▫ The increase in CO2 in the atmosphere is also having a direct effect to OCEAN ACIDIFICATION. Carbon dioxide is a weak acid, which is readily soluble in seawater. ▫ As the amount of CO2 in the atmosphere  has increased from 280 ppm (pre- industrial) to 400 ppm in 2015, some of this excess CO2 has dissolved in surface waters, making it more acidic (current change of -0.05 pH). ▫Organisms that use CaCO3 to build their skeletons, to grow. 76 Ocean Acidification Ocean Acidification Effects of Climate Change to World’s Oceans ▫ As the temperature of the surface ocean increases, it also decreases the amount of oxygen that can dissolve in the water. ▫ Some parts of the ocean, called oxygen minimum zones (OMZ), are already very close to running out of oxygen  altogether. ▫ The largest OMZs are under the east central Pacific (200–2000 m) and at similar depths in the northern Indian ocean. 79 Hydrosphere: The Earth’s Water World