Unit D – Water Systems

Water is Key to Life without water, there would be no life – humans need 1-2 litres of water daily to keep our organs properly working – we cannot breath, digest food, or grow without water – water is also essential to the life of other animals and plants

Potable Water potable water – fresh water that is safe and suitable for drinking, free of harmful microorganisms, and does not have an unpleasant taste, smell, or appearance. – in many countries, the supply of potable water is limited

Ch Earth’s Supply of Water

Water, Water Everywhere about 70% of Earth’s surface is covered by water two types of water: – salt water – type of water with a concentration of dissolved salt averaging 3.5% – fresh water – type of water with less than one percent dissolved salt

Salinity salinity – refers to the amount of dissolved salts in water the Dead Sea, the saltiest body of water found on Earth, has a salinity of 31.5% – the average salinity of the oceans is 3.5%

Fresh vs. Salt Water of all the water found on Earth, 97% is salt water fresh water only represents 3%

Usable Fresh Water is a Scarcity of the 3% of the Earth’s water that is fresh, most of it is in a state that we cannot easily use – ice 76% – ground water 23% – lakes, rivers, wetlands 0.34% – gaseous water, soil moisture, and other water 0.66%

Three States of Water water exists in three states: – solid, liquid, and gas – the state water is in is dependent upon the temperature of the water

Liquid Water liquid water is found both above (surface water) and below (groundwater) the ground

Surface Water the oceans are massive bodies of surface salt water

Surface Water surface fresh water is found in rivers, streams, lakes, ponds, and wetlands (marshes and swamps)

Surface Water surface fresh water is also stored by humans in reservoirs such as large artificial lakes and water towers precipitation helps keep surface fresh water bodies filled

Groundwater when rain falls on soil, it soaks into the soil and flows down between the soil particles it continues to flow down into the earth until it reaches a layer that is difficult to permeate (or pass through) this may be a layer of rock or a very compact layer of clay

Groundwater groundwater zone – area where water fills all the air spaces in the soil and in the tiny cracks in the rock water table – upper surface of the groundwater zone – below the water table, water fills all the spaces of the soil – above the water table, air and water fill the spaces in the soil

Groundwater aquifer – an underground freshwater reservoir well – a long, hollow shaft drilled down into an aquifer to obtain fresh water

Groundwater

groundwater is always moving slowly until it reaches a wetland, river, lake, or ocean, or flows to the surface in what is called a natural spring

Groundwater

Solid Water (ICE) ALL of the frozen water on Earth is FRESH water WHY? – ocean water can freeze, however, salt water requires a lower temperature than fresh water does to become ice – also, because the salt in the salt water does not freeze with the water, all ocean ice becomes frozen fresh water

Solid Water frozen water occurs naturally in Earth’s polar regions and on the tops of its high mountains

Mountain Glaciers glacier – a mass of ice and overlying snow that moves slowly down the mountain slope under the influence of gravity – these occur at high elevations where the temperatures are below freezing much of the year, never giving the snow a chance to melt

Ice Sheets ice sheet – a particularly large glacier that covers the land – only two of these huge glaciers exist today: one in Greenland, and one in Antarctica polar ice cap – a term sometimes used to refer to the big ice masses at the poles

Ice Shelf ice shelf – because ice floats, when an ice sheet reaches the ocean, the ice may float on the water

Iceberg iceberg – a large section of an ice shelf that has broken off and is floating free in the water

Gaseous Water when liquid water evaporates from oceans, lakes, and rivers, it forms water vapor we cannot see water vapor, but we can feel it as humidity in the air (humidity does crazy things to some people’s hair)

Gaseous Water warm air can hold more water vapor than cold air as water vapor is carried upwards into the atmosphere, it becomes colder and condenses into droplets of water that form clouds

Gaseous Water plants and animals also release water vapor into the atmosphere animals exhale water vapor during respiration, which we can see when the air is cold transpiration – the process of water evaporation from plant leaves

The Cycling Nature of Water water cycle (hydrologic cycle) – describes the continuous movement of water on, above, or below the surface of the Earth the sun provides the thermal energy that drives the water cycle the water cycle is kind of like a “choose your own adventure” novel – at each step of the cycle, there are multiple next steps that a particle of water can take

Watersheds watershed – an area of land where all the water eventually drains into one main water body, such as a stream, river, wetland, lake, or ocean activities that affect water in one part of the watershed therefore have an effect downstream in that watershed as well

Watersheds

since water only flow downhill, highpoints in land, such as mountain ranges, create natural divides in watersheds for St. Kitts, precipitation that falls on the northeast side of the volcano will flow into the Atlantic Ocean; precipitation that falls onto the southwest side of the volcano will flow into the Caribbean Sea