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LCZO -- Geomorphology -- Stream channel geomorphology -- Puerto Rico -- (2009-2012)


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Abstract

Key science question:

• How does stream channel morphology respond to the addition of impervious cover in a humid tropical region adjusted to frequent large storms?

Urbanization through the addition of impervious cover can alter catchment hydrology, often resulting in increased peak flows during floods. This phenomenon and the resulting impact on stream channel morphology is well documented in temperate climatic regions, but not well documented in the humid tropics where urbanization is rapidly occurring. This study investigates the long-term effects of urbanization on channel morphology in the humid sub-tropical region of Puerto Rico, an area characterized by frequent high-magnitude flows, and steep coarse-grained rivers. Grain size, low-flow channel roughness, and the hydraulic geometry of streams across a land-use gradient that ranges from pristine forest to high density urbanized catchments are compared. In areas that have been urbanized for several decades changes in channel features were measurable, but were smaller than those reported for comparable temperate streams. Decades of development has resulted in increased fine sediment and anthropogenic debris in urbanized catchments. Materials of anthropogenic origin comprise an average of 6% of the bed material in streams with catchments with 15% or greater impervious cover. At-a-station hydraulic geometry shows that velocity makes up a larger component of discharge for rural

channels, while depth contributes a larger component of discharge in urban catchments. The average bank-full cross-sectional area of urbanized reaches was 1.5 times larger than comparable forested reaches, and less than the world average increase of 2.5. On average, stream width at bank-full height did not change with urbanization while the world average increase is 1.5 times. Overall, this study indicates that the morphologic changes that occur in response to urban runoff are less in channels that are already subject to frequent large magnitude storms. Furthermore, this study suggests that developing regions in the humid tropics shouldn’t rely on temperate analogues to determine the magnitude of impact of urbanization on stream morphology.

References to Other Datasets:
Cross sections, grain size, and longitudinal measurements for 14 gaged streams in the NE PR region. Cross sections, grain size, longitudinal profiles, and low flow velocity for 42 field sites across a gradient of land use in the NE region of PR
Relevant Publications:

Pike AS, Scatena FN. 2010. Riparian indicators of flow frequency in a tropical montane stream network. Journal of Hydrology 382 : 72-87. DOI: 10.1016/j.jhydrol.2009.12.019

Phillips CB, and Scatena FN. 2012. Reduced channel morphological response to urbanization in a flood-dominated humid tropical environment. Earth Surface Processes and Landforms. DOI: 10.1002/esp.3345. http://onlinelibrary.wiley.com/doi/10.1002/esp.3345/full

Subject Keywords

Coverage

Spatial

Coordinate System/Geographic Projection:
WGS 84 EPSG:4326
Coordinate Units:
Decimal degrees
Place/Area Name:
Northeastern Puerto Rico and the Luquillo Mountains, Puerto Rico
North Latitude
18.3844°
East Longitude
-66.0529°
South Latitude
18.2161°
West Longitude
-66.0706°

Temporal

Start Date:
End Date:

Content

ReadMe.md

LCZO -- Geomorphology -- Stream channel geomorphology -- Puerto Rico -- (2009-2012)


OVERVIEW

Description/Abstract

Key science question: • How does stream channel morphology respond to the addition of impervious cover in a humid tropical region adjusted to frequent large storms?

Urbanization through the addition of impervious cover can alter catchment hydrology, often resulting in increased peak flows during floods. This phenomenon and the resulting impact on stream channel morphology is well documented in temperate climatic regions, but not well documented in the humid tropics where urbanization is rapidly occurring. This study investigates the long-term effects of urbanization on channel morphology in the humid sub-tropical region of Puerto Rico, an area characterized by frequent high-magnitude flows, and steep coarse-grained rivers. Grain size, low-flow channel roughness, and the hydraulic geometry of streams across a land-use gradient that ranges from pristine forest to high density urbanized catchments are compared. In areas that have been urbanized for several decades changes in channel features were measurable, but were smaller than those reported for comparable temperate streams. Decades of development has resulted in increased fine sediment and anthropogenic debris in urbanized catchments. Materials of anthropogenic origin comprise an average of 6% of the bed material in streams with catchments with 15% or greater impervious cover. At-a-station hydraulic geometry shows that velocity makes up a larger component of discharge for rural channels, while depth contributes a larger component of discharge in urban catchments. The average bank-full cross-sectional area of urbanized reaches was 1.5 times larger than comparable forested reaches, and less than the world average increase of 2.5. On average, stream width at bank-full height did not change with urbanization while the world average increase is 1.5 times. Overall, this study indicates that the morphologic changes that occur in response to urban runoff are less in channels that are already subject to frequent large magnitude storms. Furthermore, this study suggests that developing regions in the humid tropics shouldn’t rely on temperate analogues to determine the magnitude of impact of urbanization on stream morphology.

Creator/Author

Phillips, C.B.

CZOs

Luquillo

Contact

Miguel Leon, Miguel.Leon@unh.edu

Subtitle

Channel Morphology Surveys




SUBJECTS

Disciplines

Geomorphology

Topics

Geomorphology

Subtopic

Stream channel geomorphology

Keywords

Geomorphology|Urbanization|Streams

Variables

Variables ODM2

Grain size|Friction velocity




TEMPORAL

Date Start

2009-07-03

Date End

2012-06-21




SPATIAL

Field Areas

Northeastern Puerto Rico and the Luquillo Mountains

Location

Puerto Rico

North latitude

18.384404999999997

South latitude

18.216110999999998

West longitude

-66.070649

East longitude

-66.052903




REFERENCE

CZO ID

2631



Additional Metadata

Name Value
czos Luquillo
czo_id 2631
keywords Geomorphology, Urbanization, Streams
subtitle Channel Morphology Surveys
disciplines Geomorphology

Related Resources

This resource is referenced by Phillips CB, and Scatena FN. 2012. Reduced channel morphological response to urbanization in a flood-dominated humid tropical environment. Earth Surface Processes and Landforms. DOI: 10.1002/esp.3345. http://onlinelibrary.wiley.com/doi/10.1002/esp.3345/full

How to Cite

Phillips, C. (2020). LCZO -- Geomorphology -- Stream channel geomorphology -- Puerto Rico -- (2009-2012), HydroShare, http://www.hydroshare.org/resource/b538d75e180a424ca38d54e28500d33e

This resource is shared under the Creative Commons Attribution CC BY.

http://creativecommons.org/licenses/by/4.0/
CC-BY

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