Unit 3.1: Hydro Balance and groundwater Flashcards
What percentage of water on earth is salty and in the ocean and what percentage is freshwater?
Oceans have 97.2% and freshwater is 2.8%
What is the Hydrosphere?
Various flows of water within the spheres of the Earth’s system.
Does water enter or exit Earth’s system?
No.
What is the Hydrological balance?
it is a method for accounting for all water in the system. There are inputs, outputs, and storage.
What is input and how does it happen?
Input is any form of precipitation.
- Interception: precipitation that is caught by vegetation. The amount that is caught depends on structure of vegetation.
- Infiltration: Precipitation that is absorbed by surface and recharges the soil water. Amount depends of physical characteristics of soil, type and extent of vegetation cover, slope of surface, and duration/nature of rain.
- Percolation: Precipitation percolates through soil to deeper layers.
What is output and how does it happen?
Output is evaporation and transpiration.
- Evaporation: Water turns from liquid to gas. The amount depends on temperature, humidity, and winds.
- Transpiration: A cooling mechanism for plants where they “breath” and change water from a liquid to water vapour through photosynthesis.
- Evapotranspiration: In physical geography, they consider evaporation and transpiration the same thing and call it this.
What are two forms of evapotranspiration depending on the availability of water?
- Potential Evapotranspiration: the maximum amount of water that can be lost to the atmosphere from surface with abundant available water.
- Actual Evapotranspiration: the amount of water that can be lost to atmosphere from surface with a certain (limited) amount of available water.
What is the storage of water?
water in oceans, lakes, rivers, ice, groundwater etc.
What is runoff?
Occurs when precipitation exceeds amount that can infiltrate the soil so it runs overland. It is also known as overland flow.
In terms of the Hydrosphere, what is the difference between the global scale and the local scale.
The global scale is a closed system and input has to equal output.
The local scale is an open system and does not have to balance.
What is the equation for the Earth’s water budget?
Output + Storage = Input
When does actual evapotranspiration equal potential evapotranspiration?
When supply exceeds demand and excess is used to recharge soil water supply.
When is potential evapotranspiration greater than actual evapotranspiration?
When demand exceeds supply, water is taken from storage if available. If sufficient then they are equal but if there is not enough then is it not equal.
What is groundwater?
Water found beneath Earth’s surface in sediment and rocks. It is slower to respond to droughts than surface water.
The amount of water is dependent on what 3 factors?
- Percolation: Movement of precipitation through narrow channels.
- Porosity: Available airspace between soil particles, rock, or sediment where water can rest.
- Permeability: The ease which water can move through soil, sediment, or rock.
