9390

• UCREFRP Catalog Number: 9390
• Author: Webb, R. H., T. S. Melis and R. A. Valdez.
• Title: Observations of Environmental Change in Grand Canyon, Arizona.
• USFW Year: 2002.
• USFW - Doc Type: 02-4080,
• Copyright Material: NO

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CONTENTS

INTRODUCTION...................................................................................................................... .......................... 1

PURPOSE AND SCOPE .... ................................... ...................... ..... ......... .............. ...... ......... ............................. 2

Units and Nomenclature................................................................................................................... ........... 2

Acknowledgments.................................................................................................................. ..................... 3

SOURCES OF INFORMATION...................................................................................................................... ... 3

The Old Timers.......................................................................................................................... ................. 3

Other Pre-Dam or 1960s River Runners..................................................................................................... 4
Diaries and Other Accounts........................................................................................................................ 5

Repeat Photography..................................................................................................................... ............... 5

Interviews and Interpretation of Observations ....... .................. .................. ....... ............................. ............. 5
SPECIFIC CHANGES OBSERVED IN GRAND CANYON ............................................................................ 7

Aesthetics in Grand Canyon........................................................................................................................ 7

Water Temperature................................................................................................................... ................... 8

Geomorphology.................................................................................................................... ....................... 8

Debris Flows and Floods.................................................................................................................... 8

Rockfalls........................................................................................................................ .................... 13

Rapids........................................................................................................................ ......................... 13

Sand Bars................................................................................................................................ ........... 15

Channel Bars........................................................................................................................... ........... 17

Driftwood.......................................................................................................................... .......................... 18

Riparian and Desert Vegetation .................... ....................... .................... ............................ ..... ...... ............ 18

Riparian Vegetation..................................................................................................................... ...... 18

Marshes....................................................................................................................... ....................... 20

Desert Vegetation...................................................................................................................... ......... 21

Terrestrial Animals.......................................................................................................................... ............ 23

Birds and Bats............................................................................................................................ ........ 23

Insects....................................................................................................................... .......................... 24

Beavers............................................................................................................................ ................... 24

Otters........................................................................................................................... ....................... 24

Large Mammals .. .............. .............. ......................................... ......... ......... ... ...... .............. ......... ........ 26

Fishes.............................................................................................................................. ............................. 29

CONCLUSIONS...................................................................................................................... ............................ 30

REFERENCES CITED. ................................................... ......... ......................... .................................. ................ 32

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