Hydrologic Measurement
•
•
•
•
•
•
Precipitation
Evaporation
Streamflow
Channel Properties
Topography
GIS datasets
Reading: Applied Hydrology Chapter 6
Hydrologic Measurement
Precipitation, Climate, Stream Gaging
Water Quality Sampling
Precipitation Station
• Tipping Bucket Raingage
– The gauge registers
precipitation (rainfall) by
counting small increments of
rain collected.
– When rain falls into the funnel it
runs into a container divided into
two equal compartments by a
partition
– When a specified amount of rain
has drained from the funnel the
bucket tilts the opposite way.
– The number and rate of bucket
movements are counted and
logged electronically.
Tipping bucket rain gage
Weather/climate station
• Following variables
are recorded
– Wind
velocity/direction
– Rainfall
– Relative humidity and
temperature
– Radiation
Components of a weather station
Anemometer
Tipping bucket raingage
Radiometer
Relative humidity
and temperature
Precipitation (continued)
• Snow Pillows
http://wsoweb.ladwp.com/Aqueduct/snow/pillow.htm
Snow Pillows
8
Evaporation pan
Measuring streamflow
Streamflow using a boat
Tag line
Measurement at high flows
Using stream gaging cable
car
From bridge
Acoustic Doppler Current Profiler
13
Schematic of a stilling well gaging
station
Pressure transducer gaging station
Stream Flow Rate
Water Surface
Height
60%
above
bed
40%
wi
i 1
Depth
Averaged
Velocity
in
di
Velocity
Velocity profile in stream
Discharge at a cross-section
 
Q   V  dA
A
n
Q   Vi * d i * wi
i 1
Example
Colorado River at Austin
i
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
0
12
32
52
72
92
112
132
152
167
182
197
212
227
242
257
272
287
302
317
325
depth
(ft)
d
0
3.1
4.4
4.6
5.7
4.5
4.4
5.4
6.1
5.8
5.7
5.1
6.0
6.5
7.2
7.2
8.2
5.5
3.6
3.2
0.0
velocity
(ft/s)
V
0
0.4
0.9
1.1
1.3
0.7
0.9
1.4
2.0
2.2
2.5
3.1
3.1
3.0
2.6
2.0
1.6
2.0
1.6
1.2
0.0
Distance
0
0
1
2
3
Depth
distance
(ft)
4
5
6
7
8
9
25
50
75
100
125
150
175
200
225
250
275
300
325
Example (Cont.)
i
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
0
12
32
52
72
92
112
132
152
167
182
197
212
227
242
257
272
287
302
317
325
Depth
(ft)
d
0
3.1
4.4
4.6
5.7
4.5
4.4
5.4
6.1
5.8
5.7
5.1
6.0
6.5
7.2
7.2
8.2
5.5
3.6
3.2
0.0
Velocity Width
(ft/s)
(ft)
V
w
0
6
0.4
16.0
0.9
20.0
1.1
20.0
1.3
20.0
0.7
20.0
0.9
20.0
1.4
20.0
2.0
17.5
2.2
15.0
2.5
15.0
3.1
15.0
3.1
15.0
3.0
15.0
2.6
15.0
2.0
15.0
1.6
15.0
2.0
15.0
1.6
15.0
1.2
11.5
0.0
4.0
325
Area Discharge
(ft2)
(ft3/s)
A
Q
4.7
0.0
49.6
18.4
88.0
76.6
92.0
100.3
114.0
152.8
90.0
63.9
88.0
76.6
108.0
153.4
106.8
216.7
87.0
193.1
85.5
214.6
76.5
234.1
90.0
280.8
97.5
288.6
108.0
283.0
108.0
220.3
123.0
191.9
82.5
168.3
54.0
84.8
36.8
43.4
3.2
0.0
1693.0 3061.4
Distance
0
25
50
75
100
125
150
175
200
0
1
2
3
Depth
Distance
(ft)
4
5
6
7
8
9
Q = 3061 ft3/s
V = Q/A = 1.81 ft/s
225
250
275
300
325
Rating Curve
• It is not feasible to measure flow daily.
• Rating curves are used to estimate flow from stage
data
• Rating curve defines stage/streamflow relationship
20
18
16
Stage (ft)
14
12
10
8
6
4
2
0
0
5000
10000
15000
20000
25000
30000
Discharge (cfs)
19
http://nwis.waterdata.usgs.gov/nwis/measurements/?site_no=08158000
Discharge Gage
Height
(ft3/s)
(ft)
20
1.5
131
2.0
307
2.5
530
3.0
808
3.5
1130
4.0
1498
4.5
1912
5.0
2856
6.0
3961
7.0
5212
8.0
6561
9.0
8000
10.0
9588
11.0
11300
12.0
13100
13.0
15000
14.0
17010
15.0
19110
16.0
21340
17.0
23920
18.0
26230
19.0
28610
20.0
http://www.drought.unl.edu/dm/archive.html
Water Watch
http://waterwatch.usgs.gov/new/
Improvements from Senate Bill 2:
Instream Flow requirements
• Requires TPWD,
TWDB, TCEQ to
develop procedures
for defining instream
flow requirements
• Implemented on
priority study regions
by 2010
• Based on fish habitat
analysis
Trinity
Brazos
Sabine
Guadalupe
San Antonio
Priority Study Regions
Process Flowchart
Criterion
Hydrodynamic
Model
Depth &
velocity
Habitat
Species
groups
Model
SMS/RMA2
ArcGIS
Instream Flow
Decision Making
Habitat
Descriptions
Data Collection and
some statistics
Study Area (Guadalupe river near Seguin, TX)
1/2 meter Digital Ortho Photography
Depth Sounder (Echo
Sounder)
The electronic depth sounder operates in a similar way to radar It
sends out an electronic pulse which echoes back from the bed. The
echo is timed electronically and transposed into a reading of the
depth of water.
Acoustic Doppler Current Profiler
Provides full profiles of water current speed and
direction in the ocean, rivers, and lakes. Also used
for discharge, scour and river bed topography.
Measurement System
Computer and power
setup
GPS
Antenna
Depth
Sounder
Channel Bed Soundings
Bathymetry from Side-Scanning Sonar
Channel demo
National Elevation Dataset
http://ned.usgs.gov/
• Digital Elevation
Model with 1 arcsecond (30m) cells
• Seamless in 1° blocks
for the United States
• 10 billion data
• Derived from USGS
1:24,000 quadrangle
sheets
Get the data:
http://seamless.usgs.gov/
Digital Elevation Model (DEM)
720 720
Contours
740
720
700
680
740 720 700
680
Austin West 30 Meter DEM
Eight Direction Pour Point Model
32
64
16
8
128
1
4
2
Water flows in the direction of steepest descen
Flow Direction Grid
32 64 128
16
8
1
4
2
Delineation of Streams and
Watersheds on a DEM
Watersheds of the US
2-digit water resource regions
8-digit HUC watersheds
Watershed Hierarchy
Digit #
2
4
6
8 HUC
10
12
NHDPlus
Available
In Progress
Watershed of Brushy Bend
HUC12 number
LIDAR surveying
LIDAR (Light Detection and Ranging; or Laser Imaging Detection and Ranging) is
a technology that determines distance to an object or surface using laser pulses.
Like the similar radar technology, which uses radio waves instead of light, the
41
range to an object is determined by measuring
the time delay between
transmission of a pulse and detection of the reflected signal.
3-D detail of the Tongue river at the WY/Mont border from LIDAR.
Roberto Gutierrez
University of Texas at Austin
http://srtm.usgs.gov/
HydroSheds derived from
SRTM
http://hydrosheds.cr.usgs.gov/
River networks
for 8-digit HUC
watersheds
http://nhd.usgs.gov/
Lower West Fork, Trinity River Basin
HUC = 12030102
1:250,000 Scale Soil Information
http://www.ncgc.nrcs.usda.gov/products/datasets/statsgo/
Ssurgo for Travis County
103 soil map units described by 7530 polygons of
average area 35.37 ha (87 acres)
National Land Cover Dataset
Get the data:
http://seamless.usgs.gov/