UNITED STATES DEPARTMENT OF THE INTERIOR J. A. Krug, Secretary GEOLOGICAL SURVEY W. E. Wrather, Director Water-Supply Paper 994 CLOUDBURST FLOODS IN UTAH 1850-1938 By RALF R. WOOLLEY With a chapter on physiographic features By RAY E. MARSELL and a FOREWORD by NATHAN C. CROVER UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON : 1946 For sale by the Supt. of Documents, U. S. Government Printing Office, Washington 25, D. C. Price $1.50 CLOUDBURST a definition The term "cloudburst" is commonly used to designate a tor­ rential downpour of rain which by its spottiness and relatively high intensity suggests the bursting and discharge of a whole cloud at once. Cloudbursts are usually associated with thunder­ storms; they may occur anywhere but generally over a relatively small area. They are common in the hilly and mountainous dis­ tricts of the West, and the resulting floods pouring out from the small precipitous catchment basins are flashy and often destructive. CONTENTS Page Cloudburst a definition____-___---__--__-_______--_--_-__-__..-.._..,-_-_ ii Foreword, by Nathan C. Grover---.-...-..----__________________________ 1 Abstract.________-_-___----------__--_---_-_---_-_-..-.. ___-_-._____ 5 Authorization ___________________..___..---__--____-_-_..________ ._-______ 7 Administration and personnel____________________________________________ 7 Scope of report.___________-_--_---_----_____--_-_-_---_--_-_____---__- 8 Cooperation and basic data.---_--_--_-------_-_---------_--_..__--___-_- 9 Previous studies____-____---_-_-------_-_--_---------___.-..---_---_-- 9 Physiographic features, by Ray E. MarselL.____-_-___---___-_-___-______ 15 Boundaries and area.-----__--__-_-------_-______---_--.____-_____- 15 Provinces.-_ ________---__--_-_--__-_--_--__------_____--__-___-- 15 General description._____________________________ ______________ 15 Drainage----------------------------------------------------- 16 Topography ____-__-._--____--_____-__-__-__--.--_--__-.--____ 16 Colorado Plateaus provmce__-_----_____----__-_________________ 18 Basin and Range province-___-___-__-__-_--_--_________--______ 20 Middle Rocky Mountains province,_____________________________ 22 Soils.......____________________________________________________ 24 Natural vegetation____-_______-_____-_--_--__----_-_-_______-____- 28 Land classification_________________________________________________ 28 Climate..--..______...______--___-_----__-____------__--____ 30 ' ! General discussion.___________________-__-_-----___.___._-_--_--.._ 30 / Meteorology.______--_--__---_--___-__.-----------____-------_---_ 32 General statement- _-___._______-___--__---.--___._---_---__-__ 32 Storm courses.__-____._-____--_____--_-----____-_---____-_--._ 34 Storm types._________-_-_-_--______---_------__-__-___--____'_ 34 Cyclonic storms._.____._______.__-__--__..__._-_._._..___. 34 Thunderstorms- ___________________________________________ 36 Relation between storms and altitude_-_---_---____--_-_--_.__-_- 39 Frequency of thunderstorms and cloudbursts._.__.__.._______..-__ 41 Cloudburst intensity duration___--_____---__--..___.-_______..__ 42 General statement-_ _______-_-_____-__-_'"-_____-__..--___--._ 42 Intensity duration...________-_____--__--.-_-__---__--__-._ 43 Factors influencing intensity_--_-----------__-------_-----_- 45 * Runoff under thunderstorm influence.--_-----------_--_-----_--- 47 Cloudburst floods______-_-__'__.______________--_-__--_-__-__-.-_______- 52 General statement.--____._-_____-______--_--__---__----___--____-_ 52 Geographic distribution-_____________.__..__________..-.-____._..__ 56 Character and extent of areas affected.-_____---___-___------_---.--- 57 Frequency... __"____--_-____-___--___-----__-_------------_-------- 58 Catchment basins______.________.__-__.__-___--__._._.__-_-__-._-- 61 Willard Creek Basins......___.__._..._....__..__..___.____.... 61 Catchment basins in the frontal range of the Wasatch Mountains between Salt Lake City and Weber Canyon.-..__..___._____-__. 62 : Parrish Creek Basin_____-_'--___.___-----_.-____--_.--__--- 63 Davis, Farmington, Ford, and Steed Creek Basins.____________ 65 SnowsHde Canyon Basin__-___-__--__-_-_-----____-___-_----__- 67 Lost Canyon Basin..........._____________________________ 69 Cottonwood Creek Basin.---___________________________________ 69 Pleasant Creek Basin________________--___:__^_______-___-,._-_ 71 ra CONTENTS Continued Page Cloudburst floods Continued Catchment basins Continued Manti Creek Basin.____.__.___________--___-______.__- 71 Chalk CreekBasin___________---_____-_----__-----__--___--__- 72 Coal CreekBasin______________.__-_____._____ 72 Kanab Creek Basin__________-_.__-_.__________________ 73 Small streams in Colorado River Basin_____________________ 74 Mudflows_________________-___________________ 75 General statement.__________________________________________ 75 Mudflows as a phase of cloudburst floods_--_-_-_-_-___--_--.___-_ 79 Mechanics of mudflows__-______-_--_--__--_-_-___--.______-_ 80 Relation of cloudburst floods and mudflows to topography and geology_ 83 Historical floods__-._______________.-_._---___________ 84 Relation of cloudburst floods to settlement and use of the land-_____________ 121 Economic importance of areas affected by cloudburst floods._-_____._______. 123 Index. __________________________--_-_--____-._--_-___i- 127 ILLUSTRATIONS Page PLATE 1. Map of Utah showing physiograpliic divisions _______________ In pocket 2. A, Wasatch Range east of Springville; B, Wasatch Range southeast of Salt Lake City_________________________ 18 3. __., Book Cliffs erosional escarpment boundary between the Canyon Lands and Uinta Basin divisions of the Colorado Plateaus province; B, A typical landscape in the Canyon Lands_____._____.________.______---__.:____ 26 4. A, Mount Ellen, Henry Mountains; B, La Sal Mountains_ __ 34 5. Little Cotton wood Canyon, Wasatch Range_______________ 42 6. Land classification map of Utah showing distribution of cloud­ burst floods.-__-___-____________________-__-_-.__ In pocket 7. Weather maps covering cyclonic storm of September 21-25, 1930_.___.________...________________--. In pocket 8. Weather maps covering cloudburst storm of August 13, 1923 __ In pocket 9. Weather maps covering cloudburst storm of August 13, 1931 __ In pocket 10. Weather maps covering storms of August 23-30, 1932________ In pocket 11. Map of Utah showing distribution of cloudburst floods and precipitation_______.___.._____________________ In pocket 12. Plan of Willard Creek showing topography and vegetal cover.. In pocket 13. A, Wasatch Mountains looking toward Parrish Canyon, near Centerville; B, Wasatch Mountains looking toward Steed Canyon, near Farmington__________________ _ ___ 66 14. A, Upper part of catchment basin on South Fork Parrish. Creek; B, Looking up Parrish Creek Basin from near west end of the south rim; C, Looking up alluvial cone at Snowslide Canyon, in Provo Canyon, near Provo:________________________ 74 15. A, Looking up Snowslide Canyon below forks, near Provo; B, Part of Snowslide Canyon catchment basin.________.--_ 82 16. A, Tributary drains in upper part of Snowslide Canyon catch­ ment basin; B, Part of west slope of Snowslide Canyon show­ ing densely wooded moist area..____________ .__ 82 IV . ILLUSTRATIONS Continued Page 17. A, View of upper part of Lost Canyon catchment basin, near Provo; B, Looking over upper part of alluvial cone into Lost Canyon, near Provo___.______________-.._-__ 82 18. Plans and profiles of Cotton wood and Pleasant Creeks______ In pocket 19. Plan and profile of Manti Creek, including North Fork.______ In pocket 20. A, Main street of Willard after flood of August 13, 1923; B, Residence at Willard after flood of August 13, 1923; C, Orchard near mouth of Farmington Canyon, flood of August 13, 1923; D, Residence and barn in wake of Parrish Creek flood of August 27, 1930_____.___.._.._..._._._...._ 90 21. Two successive mudflows near Layton._--__-_-__-__----._-_- 98 22. Location and number of damaging cloudburst floods reported in Utah from 1847 to 1938, inclusive, with dates of settlement of communities affected___--.--______--___________ In pocket 23. Map of Utah showing distribution of cloudburst floods and population._--__-___________________________________ In pocket FIGURE 1. Distribution of precipitation in Utah with relation to areas and altitudes___________________._-_____-___________ 31 2. Climatological charts for Utah showing average temperature and precipitation, 1891-1938.--_-----__-_.._------------ 33 3. Characteristics of cyclonic storm of September 22-23, 1930___ 35 4. Characteristics of cloudburst storm of August 13, 1923. _____ 37 5. Characteristics of cloudburst storm of August 13, 1931_____- 38 6. Characteristics of storms of August 26 and 29, 1932_________ 40 7. Average annual distribution of thunderstorm days at Salt Lake City ._..._......_.__..._._._..-.-______ 41 8. Graphic analysis of intensities of three cloudburst storms. _ _ _ 44 9. Association of temperature drop with deviations from mean intensity___________.--_--_-____--___--_______ 46 10. Typical regimen of Price and San Rafael Rivers____-_-_---- 53 11. Graphs showing relationship between reports of floods, settle­ ments, and population in Utah from 1847 to 1938____--- 60 12. Plan of Parrish Creek__.____,__-____-_____-___-_- ------- 64 13. Map of Parrish Creek catchment basin showing vegetal cover. 66 14. Plan of Snowslide Canyon and Lost Canyon______-___._-- 67 15. Map of Snowslide Canyon showing vegetal cover._______-_- 68 16. Map of Lost Canyon