Suspended Sediment Dynamics in Mountain Streams
of Puerto Rico
Arica Crootof
Faculty Mentors: Ellen Wohl and Frederick Scatena
Research Experiences For Undergraduates - Program in Water Research at Colorado State University - Summer 2006
Puerto Rico
Quebrada Sonadora (within LEF)
Fourth largest Caribbean island
Rio Mameyes at Rt. 3 (outside LEF)
Study
Sites
Subtropical maritime climate
Receives ~1,600mm of precipitation each year
Discharges 2.7-9.0 million metric tonnes of suspended sediment
each year
Luquillo Experimental Forest
Results
Natural vs. Development
Suspended Sediment as a pollutant
Ecological and Economic costs
Total Suspended Sediment (TSS) vs. Suspended Sediment Concentration (SSC)
Biocomplexity Project
Suspended Sediment Rating Curve
for Mameyes at Rt. 3
Total Suspended Solids (mg/L)
Suspended Sediment
Total Suspended Solids (mg/L)
www.experience-puertorico.com/ map/isla(new).html
Suspended Sediment Rating Curve
for Quebrada Sonadora
Discharge (mm of runoff/day)
Hypotheses
TSS will be positively correlated to a river’s discharge and will best be
described by a power function.
Rivers outside of the LEF, Rio Mameyes at Rt. 3 and Rio Fajardo, will have
greater concentrations of TSS per unit of discharge compared to the other
seven sites within the LEF.
Discharge in mm of runoff/day
Site Characteristics
Non-LTER Sites
Mameyes
Mameyes at Rt. 3 (M3)
Rio Fajardo
Rio Fajardo (RF)
Discharge (mm of runoff/day)
Outside the LEF
Elevation
range (m)
Area
2
(km )
Forest types
Bedrock
350-1050
2.65
Tabonuco, Colorado, Dwarf and Palm
Volcanoclastic
750-900
600-800
0.3108
3.263
Colorado
Colorado
Grandiorite
Grandiorite
260-415
267-465
265-665
100-1050
0.067
0.0634
0.35
17.52
Tabonuco
Tabonuco
Tabonuco and Palm
Tabonuco, Colorado, Dwarf and Palm
Volcanoclastic
Volcanoclastic
Volcanoclastic
Volcanoclastic
0-1050
34.71
Forest, Agricultural and Developed
Volcanoclastic
0-1050
38.59
Forest, Agricultural and Developed
Volcanoclastic
Conclusions
b
Sites
Q1
Q2
Q3
Sample
Max
TSS
(mg/L)
1292
1510
840.0
Sample
Min
TSS
(mg/L)
1.14
1.24
1.06
Sample
Median
TSS
(mg/L)
18.6
8.37
5.20
Sample
Max Q
(mm/day)
175.2
177.1
109.6
Sample
Min Q
(mm/day)
0.04
0.04
0.26
Sample
Median Q
(mm/day)
2.09
2.30
3.69
a
1.201
0.857
0.473
b
0.392
0.367
0.500
r
0.225
0.136
0.257
M3
920.3
1.01
3.15
50.69
0.71
3.07
0.098
1.072
0.317
MPR
2148
1.01
3.10
704.4
0.14
5.98
0.022
0.702
0.305
QG
753.5
1.45
6.99
33.33
1.3
2.59
0.233
1.480
0.417
QS
187.2
1.01
2.30
67.47
0.02
1.97
0.306
0.491
0.349
RI
289.7
1.05
2.69
429.3
2.4
7.80
-0.399
1.110
0.539
RF
6700
2.00
39.0
430.5
0.28
4.31
0.853
1.020
0.626
Objectives
Compare SS rating curves for rivers within the Luquillo Experimental Forest
(LEF) to those outside of the LEF.
Suspended Sediment Rating Curves For the
Nine Study Streams
LTER Sites
El Verde watersheds
Quebrada Sonadora (QS)
Rio Icacos watershed
Quebrada Guaba (QG)
Rio Icacos (RI)
Bisley watersheds
Quebrada 1 (Q1)
Quebrada 2 (Q2)
Quebrada 3 (Q3)
Mameyes Puente Roto (MPR)
Rivers and Roads
Develop suspended sediment rating curves for the following nine streams:
Quebrada 1, Quebrada 2, Quebrada 3, Quebrada Sonadora, Quebrada Guaba, Rio
Icacos, Rio Mameyes (Puente Roto), Rio Mameyes at Rt. 3 and Rio Fajardo.
Total Suspended Solids (mg/L)
Rating curves have been used to relate suspended sediment concentrations as a function of discharge. This study developed suspended sediment rating curves by combining data from the United States Geological Survey and Long-term Ecological
Research databases for the following nine rivers in eastern Puerto Rico: Quebrada 1, Quebrada 2, Quebrada 3, Quebrada Sonadora, Quebrada Guaba, Rio Icacos, Rio Mameyes (Puente Roto), Rio Mameyes at Rt. 3 and Rio Fajardo. Using a 95-percent
confidence interval discharge accounted for 22.5, 13.6, 25.7, 34.9, 41.2, 53.9, 30.5, 31.7, and 62.6 percent of the suspended sediment concentration variation respectively. When comparing rivers outside of the Luquillo Experimental Forest, the Rio
Mameyes at Rt. 3 and Rio Fajardo, to the other seven rivers located within the Luquillo Experimental Forest, there was no significant difference in the concentration of suspended sediment per unit of discharge. Therefore, according to the results of this
study the land use practices within the drainage basins of the Rio Mameyes at Rt. 3 and the Rio Fajardo do not significantly increase the concentration of suspended sediment per unit of discharge.
TSS mg/L = aQ
With 95% confidence
2
For the nine study streams total suspended solids can be expressed as a power
function of discharge.
Using a 95-percent confidence interval discharge accounts for 22.5, 13.6, 25.7,
34.9, 41.2, 53.9, 30.5, 31.7, and 62.6 percent of the TSS variation for the following
rivers: Quebrada 1, Quebrada 2, Quebrada 3, Quebrada Sonadora, Quebrada Guaba,
Rio Icacos, Rio Mameyes (Puente Roto), Rio Mameyes at Rt. 3 and Rio Fajardo
respectively.
Rio Mameyes at Rt. 3 and Rio Fajardo, both sites outside of the Luquillo
Experimental Forest, did not have significantly higher concentrations of suspended
sediment per unit of discharge when compared to the other seven rivers located
within the Luquillo Experimental Forest.
Acknowledgements
The author expresses her gratitude to Dr. Fredrick Scatena and Dr. Ellen Wohl for their guidance and
support throughout the REU program. In addition, this project could not have been conducted without
the wealth of data that individuals have collected for the USGS and LTER databases. Funding for the REU
Program in Water Research at CSU was provided by a grant from the The DoD's ASSURE (Awards to
Stimulate and Support Undergraduate Research Experiences) Program in partnership with the National
Science Foundation.