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BRANNER GEOLOGICAL LIBRARY
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DEPARTMENT OP THE INTERIOR
John Barton Payne, Secretary P /\A
United States Geological Survey
George Otis Smith, Director
Water-Sup^y Paper
443.
SURFACE WATER SUPM i^^^,;; -^A^
OF THE '«Co^%f^
PACIFIC SLOPE OF SOUTHERN CALIFORNIA ''
BT
H. D. McGLASHAN
Prepared In cooperatien with THE state of CALIFOBNU
WASHINGTON
OOYBRNMENT PRINTING OFFICE
1921
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CONTENTS.
Pig*.
Introduction 9
Investigations of stream flow i n California 10
Cooperation and acknowledgments 11
Definition of terms 13
Explanation of da ta 14
Conditions at gaging stations in southern California 15
Accuracy and reliability of field data and computed records 17
Convenient equivalents 18
Gaging stations 20
Tia Juana River basin : , 22
General features 22
Gaging-station records 23
Tia Juana River near Nestor, CaUf 23
Cottonwood Creek near Dulzura, Calif 24
Pine Valley Creek near Dulzura, Calif 36
Dulzura conduit near Dulzura, Calif 39
Miscellaneous measurements 43
Sweetwater River basin 44
Creneial features 44
Gaging-etation records 44
Sweetwater River near Descanso, Calif 44
Sweetwater River near Dehesa, Calif 54
Sweetwater River at Sweetwater reservoir, Calif 57
Miscellaneous measurements 58
San Diego River basin 58
General features 58
Gaging-station records 59
San Diego River at diverting dam near Lakeside, Calif 59
San Diego River at Lakeside, Calif 65
San Diego River near Santee, Calif 79
San Diego River at San Diego, Calif 83
Boulder Creek near Julian, Calif 86
Boulder Creek near Lakeside, Calif 90
Cuyamaca Water Co. 's flume at diverting dam near Lakeside, Calif. . . 93
Cuyamaca Water Co. 's flmne near Lakeside, Calif 99
South Fork of San Diego River near Alpine, Calif 108
South Fork of Cuyamaca Water Co. 's flume near Alpine, Calif 110
San Vicente Creek at Foster, Calif 113
Miscellaneous measurements 114
San Dieguito River basin 116
General features 116
Gaging-station records 116
Santa Ysabel Creek near Santa Ysabel, Calif 116
Santa Ysabel Creek near Mesa Grande, Calif 118
3
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4 CONTENTS.
San Dieguito River basin — Continued.
Gaging-station records — Continued. Page*
Santa Ysabel Creek near Ramona, Calif 125
Santa Yaabel Creek near Escondido, Calif. 133
San Dieguito River at Bernardo, Calif 140
San Dieguito River near Bernardo, Calif 143
San Dieguito River near Del Mar, Calif 146
Black Canyon Creek near Mesa Grande, Calif. 148
Temescal Creek near Almond, Calif 151
East San Pasqual ditch near Escondido, Calif. 158
Guejito Creek near E^scondido, Calif 155
West San Pasqual ditch near Escondido^ Calif 157
Santa Maria Creek near Ramona, Calif 159
Miscellaneous measurements. 165
Escondido Creek bad n .-. 165
San Luis Rey River basin 165
General features 165
Gaging-station records 166
San Luis Rey River near Warner Springs, Calif 166
San Luis Rey River near Mesa Grande, Calif 170
San Luis Rey River at diversion flume, Calif 178
San Luis Rey River near Nellie, Calif 180
San Luis Rey River near Pala, Calif 182
San Luis Rey River at Pala, Calif 191
San Luis Rey River at Bonsall, Calif 192
San Luis Rey River near Bonsall, Calif 196
San Luis Rey River near Oceanside, Calif 199
San Luis Rey River at Oceanside^ Calif 201
Canada Verde Creek near Warner Springs, Calif 202
Agua Caliente Creek near Warner Springs, Calif 202
West Fork of San Luis Rey River near Warner Springs, Calif 203
Matagual Creek near Warner Springs, Calif 206
Carrizo Creek near Warner Springs, Calif 209
Susanna Creek near Warner Springs, Calif 212
Escondido Mutual Water Co. 's canal near Nellie, Calif 215
Rincon Indian Reservation ditch near Valley Center, Calif 226
Pala Indian Reservation canal at Pala, Calif : 226
San Luis Rey ditch near San Luis Rey, Calif 228
Miscellaneous measurements 229
Santa Margarita River basin 233
General features 233
Gaging-station records 233
Temecula Creek near Temecula, Calif 233
Miscellaneous measurements 234
Santa Ana River basin • 235
General features 235
Gaging-station records 236
Santa Ana River near Mentone, Calif 236
Southern California Edison Co. 's canal and Greenspot pipe line near
Mentone, Calif 262
Mill Creek in canyon at head works of Crafton canal, Calif 280
Mill Creek at Forest Home, Calif 285
Highlands canal near Mentone, Calif 295
Redlands canal near Mentone, Calif 297
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CONTENTS. 5
Santa Ana River baflin — Continued.
Gaging-station records — Continued. Page.
Waterman Canyon Creek near San Bernardino, Calif 299
Devil Canyon Creek near San Bernardino, Calif 302
Lytle Creek at mouth of canyon near Rialto, Calif 304
Lytle Creek near San Bernardino, Calif 309
San Jacinto River near Elsinrae, Calif 318
Elsinore Lake at Elsinore, Calif 321
Temescal Creek near Elsinore, Calif. 324
Temeecal Creek near Rincon, Calif 326
San Antonio Creek near Claremont, Calif 327
San Antonio Creek near Upland, Calif 331
Mificellaneous measurements of San Antonio Oeek 342
Southern California Edison Co.'s canal near ( laremont, i.'alif 346
Chino Creek at Rincon 348
Cucamonga Creek ^ 349
Miscellaneous measurements 350
Water absorbed in sands and gravel 360
Return watersin San Bemioxiino County 361
San Gabriel River basin 371
General features 371
Gaging-station records 373
San Gabriel River above Pish Fork, near Azusa. Calif 373
San Gabriel River at headworks near Azusa, C'alif 374
San Gabriel River near Azusa. Calif 375
Fish Fork of San Gabriel River near Azusa, Calif 402
Iron Fork of San Gabriel River near Azusa, Calif V. . . 403
Coldwater Creek above mouth, Calif 404
West Fork of San Gabriel River above North Fork, Calif 405
West and North branches of North Fork of San Gabriel River at weir,
Calif 405
Southern California Edison Co. 's canal near Azusa, Calif 406
Tunnel diversion near Azusa. Calif 420
Rogers Creek near Azusa, Calif 421
San Dimas Creek near San Dimas, Calif 422
Fish Creek near Duarte, Calif 425
Sawpit Creek near Monrovia, Calif 427
Monrovia pipe line near Monrovia, Calif 430
Miscellaneous measurements 433
Water absorbed in sands and gravel 438
Los Angeles River basin 439
General features 439
Records of measurement 440
Los Angeles River at the Narrows, Calif 440
Diversions from Los Angeles River 448
Pacoima Creek near San Fernando, Calif 449
Tujunga Creek near Sunland, Calif 452
Haines Creek near Tujunga, Calif 465
Arroyo Seco near Pasadena, Calif 457
Eaton Creek near Pasadena, Calif 464
Santa Anita Creek near Sierra Madre, Calif 466
LittleSanta Anita Creek near Sierra Madra, Calif 468
Miscellaneous measurements 471
Water absorbed in sands and gravel 476
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6 CONTENTS.
BdMibu Creek basin 476
General features , 476
Gaging-station records 476
Malibu Creek near Calabasas, Calif 476
Triunfo Creek near Calabasas, Calif 480
Santa Clara River basin 482
General features .-. . . 482
Gaging-station records 483
Santa Clara River at Fillmore, Calif 483
Pirn Creek near Pirn, Calif 484
Sespe Creek near Sespe, Calif 487
Seepe Creek at Sespe, Calif 490
Santa Paula Creek near Santa Paula, Calif 492
Miscellaneous measurements 496
Ventura River basin 498
General features 498
Gaging-station records 498
Ventura River near Nordhoff, Calif 498
Ventura River near Ventura, Calif 601
Miscellaneous measurements 504
Streamflow from minor drainage basins in Santa Barbara County 605
Carpinteria Creek basin 505
Gobemador Creek near Carpinteria, Calif 505
Diversion from Gobemador Creek near Carpinteria, Calif 507
Mission tunnel near Santa Barbara, Calif 508
San Roqui Creek 508
San Jose Creek near Goleta, Calif 509
Loma Abajo River 511
Gato Creek 511
Santa Ynez River basin 512
General features 512
Gaging-station records 513
Santa Ynez River near Santa Barbara, Calif 513
Santa Ynez River near Lompoc, Calif 527
Mono Creek near Santa Barbara, Calif 536
Miscellaneous measurements 538
Miscellaneous measurements of streams in Santa Barbara County 539
Santa Maria River basin 540
General features 540
• Gaging-station records 541
Santa Maria River near Santa Maria, Calif 541
Miscellaneous measurements 542
Floods 543
Records of floods 543
Flood of 1914 544
Flood of 1891 549
Index 551
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ILLUSTRATIONS.
Pag*. Plate I. Map of a part of southern California, showing location of gaging
stations in Pacific slope drainage basinB In pocket.
II. Map of a part of southern California, showing location of gaging
stations in Pacific slope drainage basins In pocket.
III. A, Price currentmeters;£, Typical gaging station 14
IV. Water-stage recorders: A^ Stevens continuous; £, Gurley printing;
C, Friez 15
V. Concrete controls: A, San Luis Rey River near Pala, Calif.; B, Sweetwater River near Dehesa, Calif.; C, Santa Ysabel Creek
near Ramona, Calif 16
\I. Af Control of concrete and solid rock on Santa Ysabel Creek near Mesa Grande, Calif.; B, Concrete control on Sweetwater River near Descanso, Calif.; C, Wading measurement on San Gabriel River near Azusa, Calif 17
VII. Ay Sweetwater dam, September 17, 1918; B, Lake Hodges dam, San
Dieguito River 44
VIII. Murray dam, March 9, 1918; A^ Upstream side; B, Downstream side. . . 45 IX. Gaging stations: A, San Diego River at diverting dam, near Lakeside,
Calif.; B, Cuyamaca Water Co.'s flume at diverting dam, near Lakeside, Calif.; C, Cuyamaca Water Co.'s flume at Los Coches
Creek, near Lakeside, Calif 60
X. Gaging stations: A^ Santa Maria Creek near Ramona, Calif.; B, Santa Ana River near Men tone, Calif., showing vertical staff gage;
C, Tunnel diversion near Azusa, Calif., showing weir 61
XI. Well and house for water-stage recorders: A, Santa Ana River near Mentone, Calif.; B, Rogers Creek near Azusa, Calif.; C, Santa Anita Creek near Sierra Madre, Calif 236
XII. Concrete well and house for water-stage recorders: J., San Dimas Creek near San Dimas, Calif.; B, C, San Gabriel River near Azusa, Calif 237
XIIL Concrete well and house for water-stage recorders: A, Rogers Creek near Azusa, Calif. ; J5, Fish Creek near Duarte, Calif. ; C, Little Santa Anita Creek near Sierra Madre, Calif 422
XIV. Af Concrete well and shelter on Sawpit Creek near Monrovia, Calif.; B, Double concrete-boulder control on Eaton Creek near Pasa- dena, Calif.; C, Concrete well, house, and control on Arroyo Seco
near Pasadena, Calif 423
XV. Concrete well, house, and control: -4, Pacoima Creek near San Fernando, Calif.; J5, Tujunga Creek, near Sunland, Calif.; C, Haines Creek near Tujunga, Calif 450
XVI. A, Waterman Canyon Creek near San Bernardino, Calif., showing gravel and sand deposited by first high water after forest fire; Bf Foundation for Gibraltar dam, on Santa Ynez River near Santa Barbara, Calif. ; C, Cable section on Santa Ynez River near Santa
Barbara, Calif 451
XVII. Views after flood of 1914: A, Arroyo Seco near Los Angeles, Calif.; B, Ventura River near Ventura, Calif.; C, Santa Paula Creek
near Santa Paula, Calif 492
XYIII. Af San Diego River at Mission dam, near Santee, Calif., after flood of 1916; B, Gaging station on Cottonwood Creek near Dulzura,
Calif. ; C, Dulzura conduit at Barrett dam site, Calif 493
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SURFACE WATER SUPPLY OF THE PACIFIC SLOPE OF SOUTHERN CALIFORNIA.
By H. D. McGlashan.
INTRODUCTION.
Since 1 848, when repairs to a mill race near Georgetown, EJldorado County, led to the discovery of gold in California, the industrial development of the State has been closely linked with the develop- ment and utilization of its water resoiu-ces. Information concerning the quantity of water carried by the streams has been and will con- tinue to be essential to the development of these resoiu'ces, for the fundamental importance of stream-flow data is now so thoroughly recognized that it is almost impossible to finance any project de- pending on stream flow without presenting authentic records of flow covering a period of years.
On account of the pronounced differences in natural conditions — especially as regards topography, geologic formations, forests, and climate— stream-measurement work in southern California presents many problems not common to similar work in the central and northern parts of the State.
The rock formations have been badly shattered by extensive fault- ing and thus furnish great quantities of boulders. The soil is very porous and is easily eroded. The main drainage channels are com- paratively short and in the mountainous sections have very steep slopes, so that during periods of high run-off the streams have excessive velocities. An interesting example is furnished by San Gabriel River, whose source is about 10,000 feet above sea level and whose mouth is approximately 50 miles distant in an air line. The maximum ob- served velocity for the measurement of San Gabriel River near Azusa on January 19, 1916, was 30 feet per second, and the mean velocity for the measiu'ement was 22.2 feet. These high velocities produce marked changes in cross sections of channels at gaging stations.
The stream channels, even in the canyons, are imstable, and they scour and fill with unfailing regularity whenever there is a sudden change in run-off. The stream beds in the canyons are composed mainly of gravel and boulders, the size of the material depending on the slope of the channel. At the mouths of the canyons there are well-defined debris cones, where the larger part of the rolling debris is deposited. The stream channels from the debris cones to the sea
9
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10 SURFACE WATER OF PACIFIC SLOPE, SOUTHERN CALIFORNIA.
are cut through fine gravels or soils of sandy loam and are subject to alluvial and erosional stream action which results in continual shifting and changing within the channel and, during floods, even in shifting of the channels themselves.
Except at the highest elevations the vegetation consists chiefly of brush interspersed with the usual growth f oimd in similar arid r^ons. During the long dry seasons lightning and careless campers are the cause of many fires, which are, however, usually held in control by the efficient fire patrol of the United States Forest Service. Occa- sionally a fire gets beyond immediate control and bums over a small drainage basin. As a result the first heavy rainfall washes into the channels of the small streams much sand and fine gravel, at times filling them to the level of their banks with this material, which is gradually eroded after the flood stage has passed. (See PI. XVI, Af p. 451.)
In this region there are two seasons — the rainy and the dry. The rainy season usually covers less than half the year, and the greater part of the rainfall occurs during the heavy storms that affect com- paratively small areas. As a rule flood stages last only for short periods. *
INVESTIGATIONS OF STREAM FLOW IN CALIFORNIA.
The measurement of the flow of streams in California was begun by the California State engineer in 1878, in accordance with a law requiring him **to investigate the problems of the irrigation of the plains, the condition and capacity of the great drainage lines of the State, and the improvement of the navigation of rivers." The work was restricted to a few localities in the Sacramento and San Joaquin basins, the principal station being on the Sacramento at Collinsville.
The State engineer's office was discontinued in 1884, and practi- cally no further stream studies were made until 1894, when engineers of the United States Geological Smrvey were sent into California and made a few measiu'ements of streams in the semiarid parts of the State. The following year the Survey established a station on Sac- ramento River at Red Bluff and since that time it has gradually ex- tended the work imtil it now has available records of flow at about 500 stations on California streams. Many records have also been collected by private persons. The first stations were located only on streams whose waters were to be used for irrigation, but records are now available on streams adapted to all uses, including navigation, domestic water supply, and power.
The investigations of the quantity of water in the streams have been supplemented by studies of the climatic and other conditions
1 R«GOids of predpitation for 106 stations in San Diego County, oorering periods varying flrom 1 year to 65 years, are presented in connection with a discussion of the ground waters of the western part of the county ^^ \. J. Ellis and C. H. Lee, published by the U. S. Geological Survey as Water-Supply Paper 44A
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OOOPEBATION AND ACKNOWLEDGMENTS. H
affecdng stream flow, and a mass of valuable information has thus been collected affording data for all phases of hydraulic work.
The stream-flow records collected by the Survey and cooperating ^parties up to the end of June, 1912, were assembled and published in 1012 and 1913 as three water-supply papers bearing titles as follows:
298. Water reeources of Oalifoniia, Part I, Stream measurements in Sacramento
River basin.
299. Water resources of California, Part II, Stream measurements in San Joaquin
River basin. •
300. Water resources of OaHfomia, Part III, Stream measurements in Great Basin
and Pacific coast river basins.
The records for the Pacific slope of southern CaUfornia, including those published in Water-Supply Paper 300 and records collected up to September 30, 1918, are presented in this report. The area covered and the location of the gaging stations maintained are shown on the topographic maps forming Plates I and II (in pocket).
COOPERATION AND ACKNOWLEDGMENTS.
Cooperation in stream measurements between the United States (Geological Survey and State of California was first provided for by the State legislature in an act approved March 16, 1903. This act covered the period from July 3, 1903, to June 30, 1905, and was in sub- stance as follows :
The State Board of Examiners are hereby empowered to enter into contracts with the Director of the United States Geological Survey for the purpose of making topo- graphic mape to the extent of twenty thousand dollars; also for the purpose of gaging streams; surveying reservoir sites and canal locations, for the conservation and utili- zation of the flood and storm waters of the State, to the extent of fifteen thousand dollars. ♦ * *
Similar acts, approved March 20, 1905, and March 11, 1907, provided for the continuation of the work until June 30, 1909, with an increased biennial appropriation of $30,000 for topography and $20,000 for hydrography. The act of March 11, 1907, named the Department of Engineering of the State of California as the cooperat- ing party.
An act placing cooperation between the State of California and the United States Geological Survey on a permanent basis was approved April 22, 1909, and provided as follows:
The Department of Engineering is hereby empowered to carry on topographic staveys and investigations into matters pertaining to the water resources of the State along the lines of hydrography, hydro-economics and the use and distribution of water for agricultural purposes, and to that end, where possible and to the beet interest of the State, shall enter into contracts for cooperation with the different departments of the Federal Government in such amounts as may be an equitable and necessary division of the work. The State engineer, with the consent of the governor, may maintain and continue such investigations where there is available money not covered by
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12 SURFACE WATER OF PACIFIC SLOPE, SOUTHERN CALIFORNIA.
cooperation contract. For the permanent maintenance of said surveys and investiga- tions there is hereby continuously appropriated out of the general fund of the State treasury for each and every fiscal year, commencing with the date upon which thiis act becomes effective, the sum of thirty thousand dollars.
Of this sum $9,000 is allotted annually to investigations of water resources.
In 1911 the California Legislature provided for a State Board of (Control (Water Powers) to pass on matters pertaining to the appro- priation of water for power development, and for a Conservation Com- mission to investigate and collect information concerning forestry, water, and other natural resources and their use, for the purpose of revising the laws of the State relating thereto. The legislature of 1912 transferred the duties of the State Board of Control (Water Powers) to the State Water Commission.
The members of the Conservation Commission were George C. Par- dee, chairman; Francis Cuttle, and J. P. Baumgarten; of the State Water Commission, Hiram W. Johnson, governor; Charles D. Marx, chairman; S. C. Graham; Harold T. Power; and W. F. McQure, State engineer. Louis R. Glavis was appointed secretary of both com- missions and was later succeeded by Josephine A. Patten. These commissions made substantial appropriations for stream-gaging work in cooperation with the Geological Survey, and as a result a large number of new river-measurement stations were established and old stations were improved.
In the present work the State of California is represented by the Department of Engineering, State of California, W. F. McClure, State engineer, and the State Water Commission. The members of this commission are William D. Stephens, governor (ex officio); W. F. McClure, State engineer (ex officio) ; A. E. Chandler, president; W. A. Johnstone; and Irving Martin. Josephine A. Patten is secretary.
The United States Forest Service, United States Weather Bureau, United States Indian Office, Los Angeles County, the cities of San Diego and Santa Barbara, the Sweetwater Water Co., the CHiyamaca Water Co., and the Voloan Land & Water Co. have also cooperated, and assistance has been rendered and many complete records of stream flow fiunished by other companies and private persons to whom credit is given in connection with the published data.
The earliest stream-gaging work in the State, beginning in 1878, was carried on imder the direction of William Ham. Hall, State engi- neer, by A. Boschke and other assistant engineers, among whom was C. E. Grunsky, who continued in charge of office computation and frequently acted as hydrographer until the State Engineer's Depart- ment was abolished. Work by the United States Geological Survey was begun in 1894, imder the direction of F. H. NeweU, chief hydrog- rapher, by Arthur P. Davis, and Joseph B. Lippincott. On the establishment of the United States Reclamation Service in 1902, Mr.
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DEFINITION OF TERMS. 13
lippincott beoame supervising engineer for California, and the field work was continued under his direction by William B. Qapp and Samuel G. Bennett, until the separation of the Reclamation Service from the Geological Survey in 1906, when Mr. Clapp became district engineer. On Mr. Qapp's death in December, 191 1, H. D. McGlashan was appointed district engineer.
DEFINITION OF TERMS,
The volume of water flowing in a stream — the ** run-off*' or ** dis- charge'*— is expressed in various terms, each of which has become associated with a certain class of work. These terms may be divided into two groups — (1) those that represent a rate of flow, as second- feet, gallons per minute, miner's inches, and discharge in second-feet per square mile, and (2) those that represent the actual quantity water, as run-off in depth in inches, acre-feet, and millions of cubic feet. The principal terms used in this report are second-feet, second- feet per square mile, run-off in inches, and acre-feet. They may be defined as follows:
** Second-feet" is an abbreviation for **cubic feet per second." A second-foot is the rate of discharge of water flowing in a channel of rectangular cross section 1 foot wide and 1 foot deep at an average velocity of 1 foot per second. It is generally used as a fimdamental imit from which others are computed by the use of the factors given in the tables of convenient equivalents (p. 18).
** Second-feet per square mile" is the average number of cubic feet of water flowing per second from each square mile of area drained, on the assumption that the run-off is distributed imiformly both as regards time and area.
** Run-off (depth in inches)" is the depth to which an area would be covered if all the water flowing from it in a given period were uniformly distributed on the surface. It is used for comparing run- off with rainfall, which is usually expressed in depth in inches.
An * ^acre-foot," equivalent to 43,560 cubic feet, is the quantity required to cover an acre to the depth of 1 foot. The term is com- monly used in connection with storage.
^'Miner's inch" represents a rate of flow and varies in different States, as noted in the table of convenient equivalents (p. 19). In California it was legalized by an act approved March 23, 1901, as one-fortieth of a second-foot. Prior to the passage of this act the common usage was one-fiftieth of a second-foot. The act reads as follows:
Section 1. The standard miner's inch of water shall be equivalent or equal to IJ cubic feet of water per minute, measured through any aperture or orifice.
Sec. 2. All acts or parts of acts inconsistent with the provisions of this act are hereby repealed.
Sec. 3. This act shall be in effect and force sixty days ffom and after its passage.
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14 SURFACE WATER OF PACIFIC SLOPE, SOUTHERN CALIFORIOA.
One-fiftieth of a second-foot is still generally used in southern California.
The following t^ms not in common use are here defined:
'^Stage-discharge relation/' an abbreviation for the term ^'relation of gage height to discharge.
' 'Control/' a term used to designate the natural section or stretch of the channel, or artificial structure below the gage that determines the stage-discharge relation at the gage. It should be noted that the control may not be the same section or sections at all stages. (See Pis. V and VI.)
The ''point of zero flow*' for a gaging station is that point on the gage — the gage height — at which water ceases to flow over control.
EXPIiANATION OF DATA.
The data presented in this report cover the climatic or water year beginning October 1 and ending September 30. At the 1st of Jan- uary in most parts of the United States much of the precipitation in the preceding three months is stored as groimd water, in the form of snow, or in ponds, lakes, and swamps, and this stored water passes off in the streams during the spring break-up ; at the end of Septem- ber, on the other hand, the only stored water available for run-off is possibly a small quantity in the ground; therefore the run-off for a year beginning October 1 is practically all derived from precipitation in that year.
The base data collected at gajging stations (PI. HI, B) consist of records of stage, measurements of discharge, and general information used to supplement the gage heights and discharge measurements in determining the daily flow. The records of stage are obtained either from direct readings on a staff gage or from a water-stage recorder (PI. IV) that gives a continuous record of the fluctuations. Measure- ments of discharge are made with a current meter which is operated from a bridge, a car suspended on a cable, or by wading (PL VI, C), the method adopted depending on the conditions at the station. The general methods are outlined in standard textbooks on the measiu-e- ment of river discharge.
From the discharge measurements rating tables are prepared that give the discharge for any stage, and these rating tables, when applied to the gage heights, give the daily discharge from which the monthly and yearly mean discharge is determined.
The data presented for each gaging station in the area covered by this report comprise a description of the station, a table giving results of discharge measurements, a table showing the daily discharge of the stream, and a table of monthly and yearly discharge and nm-off.
If the base data are insufficient to determine the daily discharge, tables giving daily gage heights and results of discharge meaaur^- ments are published.
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U. S. GEOLOGICAL SURVEY
WATER-SUPPLY PAPER 447 PLATE III
A, PRICE CURRENT METERS.
B. TYPICAL GAGING STATION.
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CX>KDinONS AT QAGIKG STATIONS. 16
The description of the station gives, in addition to statements r^arding location and equipment, information in regard to any con- ditions that may affect the constancy of the stage-discharge relation, covering such subjects as the shifting of control, and the cause and effect of backwater; it gives also information as to diversions that decrease the flow at the gage, artificial regulation, approximate ele- vation above sea level, maximum and minimum recorded stages, and the accuracy of the records.
The table of daily discharge gives the discharge in second-feet corresponding to the mean of the gage heights recorded each day. At stations on streams subject to sudden or rapid diurnal fluctuation the discharge obtained from the rating table and the mean daily gage height may not be the true mean discharge for the day. When such stations are equipped with water-stage recorders, the true mean daily discharge may be obtained by computing the mean daily gage height and applying it to the rating table, by averapng quantities of dis- charge for regular intervals during the day, or by means of a dis- charge integrator — an instnmient operating on the principle of the planimeter and containing as an essential element the rating curve of the station.
In the table of monthly discharge the column headed '* Maximum" gives the mean flow for the day when the mean gage height was highest. As the gage height is the mean for the day it does not in- dicate correctly the stage when the water surface was at crest height and the corresponding discharge was consequently larger than that given in the maximum column. Likewise, in the column headed ''Minimum," the quantity given is the mean flow for the day when the mean gage height was lowest. The column headed *^Mean" is the average flow in cubic feet for each second during the month. Computations recorded in the remaining columns are based on this average flow.
CONDITIONS AT GAGING STATIONS ON SOUTHERN CAIilPORNIA STREAMS.
Natural as well as artificial conditions in southern California are very unfavorable for accurate stream gaging. At practically all points where gaging stations have been maintained the stage-dis- charge relation imder natural conditions was continually changing. In establishing a gaging station a section of channel as favorable as possible is selected. On many streams the choice is confined to a short stretch on accoimt of the intensive developments already made for power and irrigation.
Artijicial controls. — In 1912 the first efforts were made to control the stage-discharge relation by artificial means in order to reduce the cost of maintenance of the stations and increase the accuracy of the records. The first experiment was made by driving short sec- Digitized byCjOOQlC
16 SURFACE WATER OF PACTFIC SLOPE, SOTTTHERN CALTPORNIA.
tions of wooden sheet piling across the channel immediately down- stream from the gage. A control constructed in this way was only temporary, as it was destroyed by the first high water, but it made conditions more stable during low water and indicated' that more permanent construction would be justified.
The next type of control built consisted of short sections of con- crete cut-oflf walls placed between large boulders, crossing the chan- nel in a more or less irregular manner. The sharp granite sand con- tinuously flowing over the crest eroded the concrete more rapidly than had been expected. Steel bands or angles, which were later embedded in the crest of the control, made this type of construc- tion fairly successful. The top of a short section of the control near the bank was left a few tenths of a foot lower than the other sections in order to direct the low-water flow past the gage. (See PI. V, -4.) On* several streams where there were no large boulders in the cross section to anchor the cut-oflf waUs, a concrete weir has been built with a rectangular notch to carry the low-watw discharge. (See PL V, C.) Some of these controls have been protected from gravel and boulders by bolting planks to the upstream or top face of the concrete. (See PI. XII, A and PI. XIV, C.)
Further study and experience indicated that certain changes in design were desirable. It was reaUzed that an artificial control should conform as closely as practicable to the natural cross section, so as not to disturb the stream and create new and artificial condi- tions which nature would immediately set about to destroy. This led to a plan for a control projecting but a short distance above the channel and having a concave profile about the same as that of the bed. It eliminated the sharp break in the crest due to the notch for low-water flow and made the stage-discharge relation always sensi- tive to slight changes in discharge. (See PL VI, B.) These controls were usually built of granite boulders of various sizes, bound together with concrete and placed so as to give a triangular cross section with a fairly sharp crest. The use of boulders obtained from the stream bed resulted in greater durabiUty and a sUght saving in cost over concrete.
Controls built as described above materially improve the per- manence of the stage-discharge relation and make possible the development of rating curves covering periods in which changes in stage are inconsiderable. There is a tendency for sand and gravel to collect immediately above and on each bank. This tendency is especially strong during seasons of comparatively low run-off. It is important that the gage or low-water section be placed close to the upstream side of the control.
Experiments are now being made with a double control — that is, two controls separated by a short stretch of channel. It appears that
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tJ. S. GEOLOGICAL SURVEY
WATER-SUPPLY PAPER 447 PLATE V
CONCRETE CONTROLS.
A, San Luis Rey River uear Pola, Calif.; B, Sweetwater River near Dehesa, Calif.; C Santa Ysabel
Creek near Ramoua, Calif. ^
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U. 8. OBOLOOICAL SURVEY
WATER-SUPPLY PAPER 447 PLATE VI
A. CONTROL OF CONCRETE AND SOUD ROCK ON SANTA YSABEL CREEK NEAR MESA GRANDE. CAUF.
B. CONCREl^E CONTROL ON SWEETWATER RIVER NEAR DESCAKSO, CAUF.
C WADING MEASUREMENT ON SAN GABRIEL RIVER NEAR AZ^^A. CALIF.
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ACCUKACY OF FIELD DATA. 17
the upper control accelerates the water, so that it transports the gravel and sand over the lower control, and leaves a well-defined pool in which the gage is placed. (See PL XIV, B.)
Water-stage recorders, — On account of the improvement resulting from the construction of artificial controls it has been considered advisable to collect gage-height records at important stations with greater acciu^cy by installing water-stage recorders (see PI. IV) that give a continuous record of stage. A record of this type is especially valuable during floods, as it not only indicates the time and duration of the maximum stage but furnishes a complete record from which the mean daily discharge may be acciu^tely computed.
On account of conditions in the channels previously explained, water-stage recorders could not be installed in the usual manner as shown in Plate III, B, The intake pipe connecting the well with the stream would fill up with sand and fine gravel diuing the first rise and thus seal the well. Intake pipes have been eliminated by building the well and shelter flush with or projecting into the stream. A number of small openings at various elevations are left in the stream face of the well and may be cleaned out from the inside as required. In most places the well and shelter must be built of reinforced concrete, in order to withstand floods. A number of types of wells and shelters have been used in southern California (see Pis. XI-XV). The latest design is shown in Plate XI, -4, and Plate XII, B and C,
ACCURACY OF FIELD DATA AND COMPUTED RECORDS.
The accuracy of stream-flow data depends primarily (1) on the permanence of the stage-discharge relation and (2) on the acciu^cy of observation of stage, measurements of flow, and interpretation of records.
A paragraph in the description of the station or footnotes added to the tables gives information regarding the (1) permanence of the stage-discharge relation, (2) precision with which the discharge rating curve is defined, (3) refinement of gage readings, (4) frequency of gage readings, and (5) methods of applying daily gage heights to the rating table to obtain the daily discharge.*
For the rating tables ** well defined '' indicates, in general, that the rating is probably accurate within 5 per cent; * fairly well defined,'* within 10 per cent; '* poorly defined,'' within 15 to 25 per cent. These notes are very general and are based on the plotting of the individual measurements with reference to the mean rating curve.
The monthly means for any station may represent with high accu- racy the quantity of water flowing past the gage, but the figures showing