BKT 2063 Chapter 6 By Dr. Shafiqur RahmanFaculty of Agro Industry and Natural Resources UMK
Water is an integral part of life on this planet. It is an odorless, tasteless, substance that covers more than three-fourths of the Earths surface.
Most of the water on Earth, 97% to be exact, is salt water found in the oceans. We can not drink salt water or use it for crops because of the salt content
The fresh water in ice caps is not available for use by people or plants. That leaves about 1% of all the Earths water in a form useable to humans and land animals. This fresh water is found in lakes, rivers, streams, ponds, and in the ground.
Only about 3% of Earths water is fresh. Two percent of the Earths water (about 66% of all fresh water) is in solid form, found in ice caps and glaciers.
The water cycle, also known as the hydrologic cycle or H 2O cycle, describes the continuous movement of water on, above and below the surface of the Earth. Water can change states among liquid, vapor, and solid at various places in the water cycle.
The water moves from one reservoir to another, such as from river to ocean, or from the ocean to the atmosphere, by the physical processes of evaporation, condensation, precipitation, i nfiltration, runoff, and subsurface flow. In so doing, the water goes through different phases: liquid, solid, and gas.
The sun, which drives the water cycle, heats water in oceans and seas. Water evaporates as water vapor into the air. Ice and snow can sublimate directly into water vapor. Evapo- transpiration is water transpired from plants and evaporated from the soil. Rising air currents take the vapor up into the atmosphere where cooler temperatures cause it to condense into clouds
The water cycle figures significantly in the maintenance of life and ecosystems on EarthBy transferring water from one reservoir to another, the water cycle purifies water, replenishes the land with freshwater, and transports minerals to different parts of the globe.
The hydrosphere is the sum total of water on Earth, except for that portion in the atmosphere. This combines all water underground as well as all freshwater in streams, rivers, and lakes; saltwater in seas and oceans; and frozen water in icebergs, glaciers, and other forms of ice.
Water resources are sources of water that are useful or potentially useful. Uses of water include agricultural, industrial, household, recreational and environmental activities. Virtually all of these human uses require fresh water.
A graphical distribution of the locations of water on Earth
Water is continually moving around, through, and above the Earth. It moves as water vapor, liquid water, and ice. It is constantly changing its form. Water on Earth is known by different terms, depending on where it is and where it came from.
Meteoric water - is water in circulationConnate water - "fossil" water, oftensaline. Surface water - water inrivers, lakes, oceans and so on. Subsurface water - Groundwater Groundwater - exists in the zone ofsaturation, and may be fresh or saline.
During the 20th century, more than half the world’s wetlands have been lost along with their valuable environmental services. Biodiversity-rich freshwater ecosystems are currently declining faster than marine or land ecosystems.
Surface waterSurface water is water in a river, lake or fresh water wetland. Surface water is naturally replenished by precipitation and naturally lost through discharge to the oceans, evaporation, evapotranspirati on and sub-surface seepage.
In order to understand drinking water contamination, it is necessary to first understand from where our drinking water comes. For most urban residents, relying upon municipal water systems, drinking water comes from two major sources: groundwater and surface water.
Groundwater refers to any subsurface water that occurs beneath the water table in soil and other geologic forms (Rail, 2000). Scientists estimate that groundwater makes up 95% of all freshwater available for drinking. Groundwater is a significant source of water for many municipal water systems in many countries of the world. Rural residents, withdrawing their water from wells, also rely upon groundwater.
Groundwater is generally stored in aqueducts, underground layers of porous rocks that are saturated with water. These aqueducts receive water as soil becomes saturated with precipitation or through stream and river runoff.
Each source of water has a unique set of contaminants; groundwater stores pesticide chemicals and nitrate while surface water contains most bacteria and other microorganisms. Because of the interconnectedness of this two water sources
The degradation of the quality of water that make it unsafe or harmful to human beings, animals and aquatic life. Disturbs the normal use of water for irrigation, agriculture, industries and human consumption. Can be caused by natural or anthropogenic process.
Biological agents - Include bacteria, parasitic fungi and protozoa Main source include human sewage, animal and plant wastes, decaying organic matter, industrial wastes etc. Chemical agents- The inorganic chemical agents like acids, salts, metals (lead and mercury)
The radioactive substances- released from nuclear wastes, nuclear plants and uraniumetc. The organic chemicals includes agrochemicals (pesticides, herbicides), detergents and chlorine containing compounds, oils, grease and plastic.
Water pollution categories depending on the source and storage of water Ground water pollution Surface water pollution Sea water pollution
Point source water pollution refers to contaminants that enter a waterway from a single, identifiable source, such as a pipe or ditch. Examples of sources in this category include discharges from a sewage treatment plant, a factory, or a city storm drain
Point source pollution - Shipyard - Rio de Janeiro
Non–point source pollution refers to diffuse contamination that does not originate from a single discrete source. NPS pollution is often the cumulative effect of small amounts of contaminants gathered from a large area. A common example is the leaching out of nitrogen compounds from fertilized agricultural lands
A polluted river draining an abandonedcopper mine on Anglesey
Water pollution is caused by point and non-point sources. Point sources include sewage treatment plants, manufacturing and agro-based industries and animal farms. Non-point sources are defined as diffused sources such as agricultural activities and surface runoffs.
In 2006, the Department of Environment (DOE) registered 18,956 water pollution point sources comprising mainly sewage treatment plants (9,060 : 47.79% inclusive of 601 Network Pump Stations), manufacturing industries (8,543 : 45.07%), animal farms (869 : 4.58%) and agro-based industries (484 : 2.55%)
Reservoirs are man-made lakes created by the damming of rivers to serve one or more purposes, such as hydropower production, water supply for drinking, irrigation and flood protection.
Valley dammed reservoirA dam constructed in a valley relies on the natural topography to provide most of the basin of the reservoir. Dams are typically located at a narrow part of a valley downstream of a natural basin
An irrigation system in northern Mexico. Waterfor agricultural use is most efficient
DamA physical barrier constructed across a river or waterway to control the flow of raise the level of water. Purpose of construction may be for flood control, irrigation need, hydro-electric power production and or recreational usage.
The World Summit on Sustainable Development (WSSD) in 2002 confirmed the importance of water and its critical relationship to other development issues that underlie efforts to achieve the Millennium Development Goals. A key target agreed at the Conference was for countries to prepare: National integrated water resources management and water efficiency plans by 2005.