EEPS Surfacewater Hydrology

Chemical Sedimentary Rock

A rock formed from the precipitation of dissolved minerals in water.

Limestone

A chemical sedimentary rock composed of calcium carbonate in warm tropical waters.

Metamorphic rock

a rock that has been changed from its original form (protolith) by heat, pressure, or chemical alteration.

Foliation 

A parallel alignment of minerals in a metamorphic rock, creating a layered or banded texture. 

Contact Metamorphism 

Metamorphism is caused by heat from a nearby magma body, by high temperature, and by low pressure. 

Regional Metamorphism

Affecting a large area, typically associated with mountain building at convergent plate boundaries. 

Protolith

The orginal, unmetamorphosed parent rock from which a metamorphic rock is formed.

Metamorphic Grade Sequence (from Shale)

Slate → Phyllite → Schist → Gneiss

Runoff

Water from precipitation that flows over the land surface instead of infiltrating into the ground. 

Infiltration

The process by which water on the ground surface enters the soil. 

Watershed (drainage basin)

The area of land where all of the water that falls in it and drains off of it goes to a common outlet.

Stream Discharge

The volume of water moving through a river channel over a specific period of time.

Recurrence Interval (T)

The average number of years between floods of a certain large size.

Flood Probability (P)

The statistical probability that a flood of a given size will be equaled or exceeded in any single year.

Stream Gage 

A station used to monitor and measure the discharge of a stream. 

Hydrograph 

A graph that plots river discharge or water level over time.

Lag time (hydrograph)

The time difference between the peak of a rainfall event and the peak discharge in a river. 

Effect of Urbanization on Flooding

Increase runoff and decreases lag time due to impermeable sruface, resulting in ‘flashier’ floods. 

Artificial Levees

Embankments constructed along a river to contain its flow and prevent flooding.

Channelization

The process of modifying a river channel to control flow.

Dam (as flood control)

A barrier constructed to hold back water, forming a reservoir that can be used to regulate river flow. 

Formula for Recurrence Interval 

T = (n+1)/m 

Relationship between recurrence interval (T) and Probability (P)

Reciprocals P = 1/T

Permeable Pavement

A surface material that allows water to pass through it reducing runoff and increasing groundwater recharge.

Magmatic Differentiation

the process by which a single body of magma can produce a variety of igneous rocks with different compositions.

Why does magmatic differentiation happened?

This occurs because as magma cools, different minerals crystallize and separate from the liquid melt, altering the remaining magma's chemistry.