hydrologic measurement
DESCRIPTION
Hydrologic Measurement. Precipitation Evaporation Streamflow Channel Properties Topography GIS datasets. Reading: Applied Hydrology Chapter 6. Hydrologic Measurement. Water Quality Sampling. Precipitation, Climate, Stream Gaging. Precipitation Station. Tipping Bucket Raingage - PowerPoint PPT PresentationTRANSCRIPT
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
Radiometer
Tipping bucket raingage
Relative humidity and temperature
Precipitation (continued)
• Snow Pillows
http://wsoweb.ladwp.com/Aqueduct/snow/pillow.htm
8
Snow Pillows
Evaporation pan
Measuring streamflow
Streamflow using a boat
Tag line
Measurement at high flows
Using stream gaging cable car
From bridge
13
Acoustic Doppler Current Profiler
Schematic of a stilling well gaging station
Pressure transducer gaging station
Stream Flow Rate
A
Q AdV
Discharge at a cross-section
Water Surface
Depth Averaged Velocity
Height above bed
%60
%40
Velocity
n
iiii wdVQ
1**
iw
id
1i ni
Velocity profile in stream
Example
distance depth velocity(ft) (ft) (ft/s)
i d V1 0 0 02 12 3.1 0.43 32 4.4 0.94 52 4.6 1.15 72 5.7 1.36 92 4.5 0.77 112 4.4 0.98 132 5.4 1.49 152 6.1 2.0
10 167 5.8 2.211 182 5.7 2.512 197 5.1 3.113 212 6.0 3.114 227 6.5 3.015 242 7.2 2.616 257 7.2 2.017 272 8.2 1.618 287 5.5 2.019 302 3.6 1.620 317 3.2 1.221 325 0.0 0.0
0
1
2
3
4
5
6
7
8
9
0 25 50 75 100 125 150 175 200 225 250 275 300 325
Distance
Dep
th
Colorado River at Austin
Example (Cont.)Distance Depth Velocity Width Area Discharge
(ft) (ft) (ft/s) (ft) (ft2) (ft3/s)i d V w A Q
1 0 0 0 6 4.7 0.02 12 3.1 0.4 16.0 49.6 18.43 32 4.4 0.9 20.0 88.0 76.64 52 4.6 1.1 20.0 92.0 100.35 72 5.7 1.3 20.0 114.0 152.86 92 4.5 0.7 20.0 90.0 63.97 112 4.4 0.9 20.0 88.0 76.68 132 5.4 1.4 20.0 108.0 153.49 152 6.1 2.0 17.5 106.8 216.7
10 167 5.8 2.2 15.0 87.0 193.111 182 5.7 2.5 15.0 85.5 214.612 197 5.1 3.1 15.0 76.5 234.113 212 6.0 3.1 15.0 90.0 280.814 227 6.5 3.0 15.0 97.5 288.615 242 7.2 2.6 15.0 108.0 283.016 257 7.2 2.0 15.0 108.0 220.317 272 8.2 1.6 15.0 123.0 191.918 287 5.5 2.0 15.0 82.5 168.319 302 3.6 1.6 15.0 54.0 84.820 317 3.2 1.2 11.5 36.8 43.421 325 0.0 0.0 4.0 3.2 0.0
325 1693.0 3061.4
0
1
2
3
4
5
6
7
8
9
0 25 50 75 100 125 150 175 200 225 250 275 300 325
Distance
Dep
th
Q = 3061 ft3/s
V = Q/A = 1.81 ft/s
19
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
0
2
4
6
8
10
12
14
16
18
20
0 5000 10000 15000 20000 25000 30000Discharge (cfs)
Stag
e (ft
)
Discharge GageHeight
(ft3/s) (ft)20 1.5
131 2.0307 2.5530 3.0808 3.5
1130 4.01498 4.51912 5.02856 6.03961 7.05212 8.06561 9.08000 10.09588 11.0
11300 12.013100 13.015000 14.017010 15.019110 16.021340 17.023920 18.026230 19.028610 20.0
http://nwis.waterdata.usgs.gov/nwis/measurements/?site_no=08158000
Water Watchhttp://waterwatch.usgs.gov/new/
http://www.drought.unl.edu/dm/archive.html
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
Priority Study Regions
Guadalupe
San Antonio
Brazos
Trinity
Sabine
Process Flowchart
Instream FlowDecision Making
HydrodynamicModel
HabitatDescriptions
HabitatModel
ArcGISSMS/RMA2 Data Collection and
some statistics
Depth & velocity
Species groups
Criterion
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
GPS Antenna
Depth Sounder
Computer and power setup
Channel Bed Soundings
Bathymetry from Side-Scanning Sonar
Channel demo
National Elevation Dataset• Digital Elevation Model with 1 arc-second
(30m) cells • Seamless in 1° blocks for the United
States• 10 billion data• Derived from USGS 1:24,000 quadrangle
sheets
http://seamless.usgs.gov/Get the data:
http://ned.usgs.gov/
Digital Elevation Model (DEM)Contours
720
700
680
740
680700720740
720 720
Austin West 30 Meter DEM
32
16
8
64
4
128
1
2
Eight Direction Pour Point Model
Water flows in the direction of steepest descent
Flow Direction Grid
32
16
8
64
4
128
1
2
Delineation of Streams and Watersheds on a DEM
Watersheds of the US
2-digit water resource regions 8-digit HUC watersheds
Hydrologic Unit Code Watersheds~ 2000 for US, about the size of counties
38
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 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 GutierrezUniversity of Texas at Austin
http://srtm.usgs.gov/
HydroSheds derived from SRTM
http://hydrosheds.cr.usgs.gov/
River networksfor 8-digit HUC watersheds
http://nhd.usgs.gov/
Lower West Fork, Trinity River BasinHUC = 12030102
http://www.horizon-systems.com/nhdplus/
NHDPlus for a Portion of Oregon
http://www.horizon-systems.com/nhdplus/
NHDPlus Reach Catchments ~ 3km2
About 1000 reach catchments in each 8-digit HUC
Average reach length = 2km 2.3 million reaches for continental US
http://www.ncgc.nrcs.usda.gov/products/datasets/statsgo/
1:250,000 Scale Soil Information
Ssurgo for Travis County
103 soil map units described by 7530 polygons of average area 35.37 ha (87 acres)
National Land Cover Dataset
http://seamless.usgs.gov/Get the data: