Surface Water

1
Surface Water
2
Water

• An essential commodity with an irregular
  distribution.
• Geographic desert / rain forest
• Temporal flood / drought

3
Consumption vs. Supply

• Adequate in most areas (at present)
• Shortages in other areas
• Importing Water
• (southern CA - imports 75 from
  200 miles away)
• Depletion
• (southern CA - drawing down lakes
  and ground water)

4
Water use is growing rapidly

• By 2050 use will exceed the flow of earth's
  rivers
• Ground water is the resource of the future
• Water availability will limit population growth -
  by statute or famine

5
Earth's Six Water Reservoirs
Oceans
97.54
- - -
1.81
- - -
Glaciers
Ground Water
0.63
98.4
1.4
0.009
Fresh Lakes / Streams
Salty Lakes / Streams
0.007
- - -
0.001
0.2
Atmosphere
6
Hydrologic Cycle

• Constant movement of Earth's water from one
  reservoir to another.

7
Hydrologic Cycle
Transpiration
Precipitation
Infiltration
Evaporation
Runoff
Percolation
8
Hydrologic Budget

• Precipitation Evaporation Transpiration
• (What goes up comes back down)
• Stream Flow Runoff Percolation Discharge
• (What goes down comes back up)
• The atmosphere, surface water bodies and ground
  water must be considered as an interconnected
  "system"

9
Water problems in Tioga County

• Surface Water
• impermeable soils / steep slopes cause
  flooding
• rapid runoff causes erosion
• Soil Zone
• slow infiltration / high water tables
  limit sewage disposal
• Ground Water
• slow-moving ground water causes poor
  water quality
• slow-moving ground water causes
  low-yield wells

10
Floods A reason to monitor streams

• Pictured The Middlebury stream
• gauge and rain gauge
• Tioga County is one of the most heavily gauged
  areas in the United States.
• Brian Guillaume and Jason Dunn's website for
  stream gauging in Tioga County.

Connect
11
Main Causes of Floods

• Rainfall
• intensity
• duration
• Snow Melt
• Dam Failure
• Combinations of the Above
• rainfall and snowmelt
• rainfall and dam failure

12
Stream Gauge Operation

• Automatic monitoring of stream
• Reporting by satellite, radio, or
• telephone
• Rapid response in emergencies
• Continuous historical record
• Tioga River at Mansfield

Connect
13
What is monitored?

• Stage
• elevation of the water above a
  reference datum
• usually measured in feet
• directly measured by the gauge
• uses
• bridge heights
• flood-prone area maps
• flood warnings
• speed of flood crest movement
• rafting / fishing

14
What is monitored? (continued)

• Discharge
• volume of water passing a given point
  in a unit of time
• usually measured in cubic feet per
  second
• not directly measured by gauge -
  estimated
• uses
• relates stream conditions to
  reservoir capacity
• better than stage for
  historical information
• predicted precipitation ---
  stream response
• contaminant dilution

15
Discharge

• Volume of water passing a given point in a
  unit of time

Q width x depth x velocity
velocity (3 feet / sec
depth (2 feet)
Q 2' x 4' x 3'/sec
Q 24 cubic feet / sec
width (4 feet)
16
Discharge is difficult to measure

• Channel shape is irregular
• (not a simple rectangle)
• Velocity is variable
• (fast at the top / slow at bottom)
• (fast in middle / slow at banks)