1.7 Flashcards
Global Hydrological System
Closed system on a global scale, but regional drainage basins are open transfers in and out.
Freshwater accounts for only 2.5% of total water, of which only a third is available for human use and is unevenly distributed.
Water Budgets
The annual balance between inputs and outputs within a system can vary with latitude.
Stores/Fluxes/Processes
Size and residence times depends on a number of factors which vary spatially and over time, these factors include: soil, geology, climate, topography, vegetation and human land-use.
Water Budgets
The annual balance between inputs and outputs within a system can vary with latitude.
River Regimes
The annual variation of river discharge at a particular point tend to follow a pattern given their location but also local geographical factors.
Normal Base Flow
The contribution to river flow from long-term storage sources e.g. permeable rocks
Rising Levels
The increase in river discharge due to an increase in surface runoff and through flow.
Bank-Full Discharge
When a river’s water level reaches the top of its channel
Falling Limb
The decline in discharge after peak flow
Lag Time
The difference in hours and minutes of peak precipitation and the time of peak river discharge. The smaller the lag time, the more vulnerable the river.
Approach Segment
The discharge of the river before the stem.
How Do Small Basins Affect Vulnerability?
Water will reach the channel rapidly as it has a shorter distance to travel.
How Do Circular Basins Affect Vulnerability?
It will take less time for the water to reach as all extremities are equidistant from the channel
How Do Large Basins Affect Vulnerability?
Water has greater distance to travel, meaning it will reach the channel slower.
How Do Elongated Basins Affect Vulnerability?
All extremities are further from the basin
