The hydrologic cycle describes the continuous movement of water above, on, and below the Earth's surface. Water exists in various states as it moves through the cycle, with the driving forces being evaporation, transpiration, condensation, infiltration, and runoff. Precipitation that falls as rain or snow infiltrates into the ground to become groundwater, is taken up by plants, or runs off as surface water into streams, rivers, and lakes, eventually draining into oceans where the cycle begins again through evaporation.

1. The Hydrologic Cycle
“All the rivers run into the sea; yet the sea is not full; unto the place from whence the
rivers come, thither they return again.” (Ecclesiastes 1:7)

2. Water is just about everywhere on Earth—
in the oceans, glaciers, rivers, lakes, air, soil, and in living tissue .

3. Water content of the hydrosphere is 1.36
billion cubic kilometers

4. Hydrologic Cycle and Interactions of Ground
Water and Surface Water
 Hydrologic cycle - describes the continuous movement of water above, on,
and below the surface of the earth.
 Surface Water
The water on the earth’s surface
occurs as streams, lakes, and wetlands, as well as bays and oceans.
also includes the solid forms of water— snow and ice.
 Ground Water
The water below the surface of the earth

6. What happens to precipitation once it has fallen on
land?
 Infiltration
A portion of the water soaks into the ground, slowly moving downward,
then laterally, finally seeping into lakes, streams, or directly into the ocean.
 Runoff
When the rate of rainfall exceeds Earth’s ability to absorb it, the surplus
water flows over the surface into lakes and streams

7. What happens to precipitation once it has
fallen on land?
 Evaporation
Much of the water that infiltrates or runs off eventually returns to the
atmosphere
 Transpiration
Some of the water that infiltrates the ground surface is absorbed by plants,
which then release it into the atmosphere
 Evapotranspiration
Because we cannot clearly distinguish between the amount of water that is
evaporated and the amount that is transpired by plants, the term
evapotranspiration is often used for the combined effect.

8. Running Water

9. Running Water
 Most of the precipitation that falls on land either enters the soil
(infiltration) or remains at the surface, moving downslope as runoff.
 The amount of water that runs off rather than soaking into the
ground depends on several factors:
(1) intensity and duration of rainfall,
(2) amount of water already in the soil,
(3) nature of the surface material,
(4) slope of the land, and
(5) the extent and type of vegetation.

11. Running Water
 Runoff initially flows in broad, thin sheets.
 This unconfined flow eventually develops threads of current that form
tiny channels called rills.
 Rills meet to form gullies, which join to form streams.
 At first streams are small, but as one intersects another, larger and larger
ones form. Eventually rivers develop that carry water from a broad
region.

12. Drainage
basin –
The land area
that contributes
water to a river
system

13. River systems involve the
entire drainage basin.
River systems can be
divided into three zones:
1. sediment production
2. sediment transport
3. sediment deposition
Drainage basins and
divides exist for all streams,
regardless of size.

14. Mandulog River

15. Mandulog River

16. Mandulog River before and after flooding
http://www.rappler.com/nation/626-heavy-rainfall,-topography-
deadly-mix-in-iligan-flooding

17. Streamflow

18. Streamflow
 Laminar Flow = very slow-moving streams; water particles move in
roughly straight-line paths that parallel the stream channel.
 Turbulent Flow = water moving in an erratic fashion that can be
characterized as a swirling motion; may exhibit whirlpools and
eddies, as well as roiling whitewater rapids

19. Flow Velocity
The ability of a stream to erode and transport material is directly
related to its flow velocity.
Several factors influence flow velocities and, therefore, control a
stream’s potential to do “work” :
(1) channel slope or gradient;
(2) channel size and cross-sectional shape;
(3) channel roughness; and
(4) the amount of water flowing in the channel.

20. Gradient and Channel Characteristics
Gradient - the slope of a stream channel expressed as the vertical drop
of a stream over a specified distance
The steeper the gradient, the more energy available for streamflow.
If two streams were identical in every respect except gradient, the stream
with the higher gradient would obviously have the greater velocity.
 Channel - a conduit that guides the flow of water
 Larger channels have more efficient flow
 smooth channel promotes a more uniform flow
 an irregular channel filled with boulders creates enough turbulence

21. Discharge
 Discharge is the volume of water flowing past a certain point in a
given unit of time.
 measured in cubic meters per second
 determined by multiplying a stream’s cross-sectional area by its
velocity (D = A * v )

23. The Work of Running
Water

24. Streams
Earth’s most important erosional
agents
Can downcut and widen their
channels
Can transport the enormous
quantities of sediment

25. Competence and Capacity
 A stream’s ability to carry solid particles is described using two criteria:
capacity and competence.
 Capacity - maximum load of solid particles a stream can transport per
unit of time.
 Competence - a measure of a stream’s ability to transport particles
based on size rather than quantity.

26. Deposition of Sediment
 Whenever a stream slows down, its velocity decreases, its
competence is reduced and sediment begins to drop out, largest
particles first.
 Sorting
a mechanism by which solid particles of various sizes are separated by
stream transport
explains why particles of similar size are deposited together.
 Alluvium
The material deposited by a stream
the general term for any stream-deposited sediment

27. Deposition of
Sediment

28. Stream Channels
(1) Bedrock Channels
(2) Alluvial Channels
composed of loosely consolidated sediment (alluvium) and therefore can
undergo significant changes in shape because the sediments are
continually being eroded, transported, and redeposited.
 2 common types of alluvial channels:
 meandering channels
braided channels.

29. Meandering Streams
 A meander, in general, is a
bend in a watercourse or river.
 A meander forms when
moving water in a stream
erodes the outer banks and
widens its valley, and the inner
part of the river has less energy
and deposits silt.
 A point bar is deposited where
the water on the inside of a
meander slows.
 Cut bank – Zone of active
erosion

30. Meanders

32. Braided Streams
- a complex network of
converging and diverging
channels that thread their
way among numerous
islands or gravel bars
- channels have an
interwoven appearance
- wide and shallow

33. Depositional Landforms

34. Deltas
Delta landforms are
sedimentary wetlands
that form at the mouths
of rivers where the
velocity of the water
slows. As the sediment
builds, triangular
landforms separate the
river into two or more
channels.
A – Structure of a simple
delta that forms in the
relatively quiet waters of
a lake
B – Growth of a simple
delta

35. Natural levees
• gently sloping deposits that are created by repeated floods
• a deposit of sand or mud built up along, and sloping away from, either side of the flood plain of a
river or stream

36. Groundwater
– Water Beneath the Surface

37. Distribution of Groundwater
 Zone of soil moisture - Some of the water that soaks in does not
travel far, because it is held by molecular attraction as a surface film
on soil particles.
 Zone of saturation - Water that is not held as soil moisture percolates
downward until it reaches a zone where all of the open spaces in
sediment and rock are completely filled with water.
 Groundwater - Water within the zone of saturation
 Water Table - The upper limit of the zone of saturation
 Unsaturated zone - The area above the water table where the soil,
sediment, and rock are not saturated

39. Porosity and Permeability
 Porosity - voids or openings where
water can soak. These openings are
similar to those of a sponge and are
often called pore spaces.
 The quantity of groundwater that
can be stored depends on the
porosity of the material, which is the
percentage of the total volume of
rock or sediment that consists of
pore spaces.
 Permeability - the ability of a
material to transmit a fluid
 Porosity alone cannot measure
a material’s capacity to yield
groundwater. Rock or sediment
may be very porous yet still not
allow water to move through it.
The pores must be connected to
allow water flow, and they must
be large enough to allow flow.

40. Aquitards and Aquifers
Impermeable layers
that hinder or prevent
water movement are
termed aquitards
 Clay is a good
example.
 Permeable rock strata
or sediments that
transmit groundwater
freely are called
aquifers
 Sands and gravels are
common examples.

42. Springs
 A natural flow of groundwater
that results whenever:
the water table intersects the
ground surface
when an aquitard blocks the
downward movement of
groundwater and forces it to
move laterally
When the permeable bed
(aquifer) outcrops in a valley

43. Springs
 Hot Spring
 By definition, the water in
hot springs is 6 – 9°C
warmer than the mean
annual air temperature
for the localities where
they occur.
 Geyser
 a hot spring that
periodically erupts
through an opening in
Earth's surface, spewing
hot water and steam up
to hundreds of feet
above the ground.

45. Geologic Work of Groundwater

46. Caverns

47. Karst
landforms