UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Water resources of the vernon irrigation district 1971

You don't seem to have a PDF reader installed, try download the pdf

Item Metadata

Download

Media
UBC_1972_A7 J63.pdf
UBC_1972_A7 J63.pdf [ 3.56MB ]
UBC_1972_A7 J63.pdf
Metadata
JSON: 1.0050550.json
JSON-LD: 1.0050550+ld.json
RDF/XML (Pretty): 1.0050550.xml
RDF/JSON: 1.0050550+rdf.json
Turtle: 1.0050550+rdf-turtle.txt
N-Triples: 1.0050550+rdf-ntriples.txt
Citation
1.0050550.ris

Full Text

WATER RESOURCES OF THE VERNON IRRIGATION DISTRICT by RONALD HARVEY JOHNSTON B.Sc.(Eng.), University of Guelph, 1968 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE in the Department of C i v i l Engineering We accept this thesis as conforming to the required standard The University of B r i t i s h Columbia November* 1971 In present ing th i s thes is in pa r t i a l fu l f i lment o f the requirements for an advanced degree at the Un ivers i t y of B r i t i s h Columbia, I agree that the L ibrary sha l l make it f r ee l y ava i l ab le for reference and study. I fu r ther agree that permission for extensive copying of th i s thes is for scho la r l y purposes may be granted by the Head of my Department or by h is representat ives . It is understood that copying or pub l i ca t ion of th is thes is fo r f i nanc ia l gain sha l l not be allowed without my wr i t ten permiss ion. Department of Civil Engineering The Univers i ty of B r i t i s h Columbia Vancouver 8, Canada Date November 26, 1971 i . ABSTRACT The Okanagan Valley i s an important agricultural area i n south-central B r i t i s h Columbia. Due to the low annual precipitation and a high rate of evapotranspiration, irrigation i s necessary for the production of most crops. Since water shortage problems in the valley are l i k e l y to arise i n the future, since irrigation accounts for over 90% of the consumptive use of water in the valley, and since data on the actual ir r i g a t i o n operation i s sparse, a detailed study was made of one d i s t r i c t . Vernon Irrigation D i s t r i c t , the largest d i s t r i c t i n the Okanagan Basin, was selected for detailed study. Its distribution system has recently been modernized. The history of the development of the d i s t r i c t i s outlined and the old system and the way in which i t operated are described. The reasons for selection of the new system, the c r i t e r i a used in i t s design, and the way in which the new system now operates are described. Particular attention i s paid to scheduling—the timing of the application of water to the crops—since this offers one of the best opportunities for the conservation of water in the future. Minor conflicts with other users of the water resource , are identified and suggestions given for minimizing such conflicts. TABLE OF CONTENTS Page ABSTRACT i LIST OF TABLES i i LIST OF FIGURES i i i ACKNOWLEDGMENTS i v Chapter I. INTRODUCTION . . . . . 1 II. VERNON IRRIGATION DISTRICT 4 III. GENERAL DESCRIPTION . k CLIMATE 6 HISTORY 8 OPERATION OF THE OLD IRRIGATION SYSTEM 14 III. NEW IRRIGATION SYSTEM 17 DESIGN 17 Comparison of Alternatives . . . . . . . . . . 17 Design C r i t e r i a for the Old Pipeline System . . 19 Duty . . . . . . . . . . . . . . . . . . . . . . . 19 Maximum Demand Rate 20 Pressure . . . . . . . . . . . . 21 OPERATION OF NEW IRRIGATION SYSTEM 21 Distribution System „ 21 Reservoir System -26 Chapter Page IV. SCHEDULING THE APPLICATION OF WATER . . 33 EQUIPMENT USED IN SCHEDULING , 33 GENERAL PROCEDURE 35 CREDIT FOR RAIN 37 CHOOSING A SITE FOR THE EVAPORIMETER 39 SCHEDULING FOR IRRIGATION DISTRICTS 39 ADVANTAGES OF SCHEDULING 40 PROBLEMS WITH SCHEDULING 41 USE OF SCHEDULING 43 V. ADDITIONAL USES OF DUTEAU CREEK 45 FISHERIES 45 FLOOD PROTECTION AT LUMBY 49 VI. PLANS FOR THE FUTURE 50 CONSTRUCTION OF ADDITIONAL STORAGE 50 MANAGEMENT . . 51 Economic Incentive 51 Extra Equipment . . . . . . . . . 52 Better Operation of Reservoirs . . . . . . . . 53 Scheduling 53 Drip Irrigation 5̂ SUMMARY 54 VII. CONCLUSIONS 56 BIBLIOGRAPHY 57 GLOSSARY 59 i i . LIST OF TABLES , Table Page I . CLIMATIC DATA 7 II. LAND USE 8 I I I . CATCHMENT AREA, STORAGE, AND GOVERNING WATER LEVELS OF VERNON IRRIGATION DISTRICT RESERVOIRS 28 i i i . LIST OF FIGURES Figure Page 1. OKANAGAN BASIN IN BRITISH COLUMBIA 5 2. HISTORIC DITCHES 10 3. NEW IRRIGATION PIPELINE 22 4. STORAGE RESERVOIRS OF VERNON IRRIGATION DISTRICT . . . 2? 5. HYDROGRAPHS OF LAKE INFLOW AND RELEASE IN HIGH FLOW YEAR 30 6. HYDROGRAPHS OF LAKE INFLOW AND RELEASE IN LOW FLOW YEAR 31 7. BALANCE SHEET 34 8. BELLANI PLATE EVAPORIMETER 36 9. OGOPOGO EVAPORIMETER 36 10. DAILY EVAPOTRANSPIRATION AT SUMMERLAND RESEARCH STATION, 1971 42 11. FLOODING AND SPAWNING LOCATION IN DUTEAU CREEK WATERSHED 46 12. DISCHARGE IN DUTEAU CREEK BELOW THE VERNON IRRIGATION DISTRICT DIVERSION, LOW FLOW YEAR, I963 47 13. DISCHARGE IN DUTEAU CREEK BELOW THE VERNON IRRIGATION DISTRICT DIVERSION, HIGH FLOW YEAR 48 i v . ACKNOWLEDGMENTS During the course of this study, many people have given freely of their time in order to assist me. To the following I express my sincere appreciationi B. S, Harvey, Irrigation Manager-Engineer, Vernon Irrigation D i s t r i c t , for his time spent i n showing the irrigation system and for access to the Vernon Irrigation D i s t r i c t records, P, Kowalchuk, Chief Water B a i l i f f , Vernon Irrigation D i s t r i c t , for his time spent showing the storage reservoirs of the D i s t r i c t , D. S, Stevenson, Irrigation Specialist, Summerland Research Station, for demonstrating scheduling and providing evaporation data, C, H, Brownlee, Irrigation Specialist, B r i t i s h Columbia Department of Agriculture, Kelowna, for time spent in discussing various aspects of irr i g a t i o n i n the area, J, Eby, Water Investigations Branch, B r i t i s h Columbia Department of Lands, Forests, and Water Resources, Victoria, for time spent discussing the design of the new irri g a t i o n system, T, J, Wilcox, Canada Department of Fisheries, Vancouver, for time spent discussing the fisheries resource of the Vernon area, S. 0, Russell, Department of C i v i l Engineering, University of B r i t i s h Columbia, Vancouver, for ably supervising the development of this thesis. 1 CHAPTER I INTRODUCTION The Okanagan Valley i s a broad, irregular r i f t - v a l l e y i n the interi o r of B r i t i s h Columbia extending approximately 120 miles north from the Canada-United States border. The average annual precipitation varies from about 15 inches i n the northern part of the valley near Vernon, which i s barely sufficient for the production of some forage and pasture crops, to about 8 inches at Osoyoos i n the south.Many crops flourish i f provided with additional moisture through i r r i g a t i o n . Since before 1900, agriculture has been the most important economic a c t i v i t y i n the valley although tourism has expanded greatly i n the l a s t decade. The ir r i g a t i o n systems which supply water for the farms were mostly begun early i n the century and consequently by the 1950's, had not only become rather obsolete i n terms of todays ir r i g a t i o n technology but also most of the systems needed rehabilitation to conserve water and increase their r e l i a b i l i t y . In the l a s t decade many of the distribution systems of the irr i g a t i o n d i s t r i c t s i n the Okanagan have been rehabilitated under the A.R.D.A. agreement •whichallows for federal and provincial assistance. With growing problems of water shortage and water pollution as the valley population and i n d u s t r i a l i - zation increases, the federal and provincial governments have undertaken a joint study of water quantity and quality management i n the Okanagan basin. 2 Since irrigation accounts for more than 90% of the consumptive use of water, familiarity with ir r i g a t i o n i s necessary in order to carry out studies of water resources i n the Okanagan Valley, Unfortunately, discharge and consumptive use data are at best scattered and incomplete and, in any case, records of the amount of ir r i g a t i o n water used, say, twenty years ago are of limited use today when irri g a t i o n practices, efficiency of application, and crops are substantially different from what they were. To obtain an understanding of irrigation practice in the Okanagan, i t was decided to study a particular i r r i g a t i o n d i s t r i c t in detail to find out how i t actually operated and to try to identify problems and conflicts with other resource users and opportunities for better management. Vernon Irrigation D i s t r i c t , the largest d i s t r i c t in the Okanagan Valley was selected for the study. Although i t has a lower water consumption per acre than other d i s t r i c t s i n the Okanagan, Vernon Irrigation D i s t r i c t i s typical in that i t has several reservoirs with a relatively complex operating pattern, and records of water a v a i l a b i l i t y and consumptive use are not available. Also replacement of the old distribution system by a new one has just been completed, thus offering an opportunity to study a modern in s t a l l a t i o n . In this thesis, the history of the development of the d i s t r i c t i s f i r s t outlined to give some background perspective, and the old system and i t s operation i s described. The reasons for selecting the new system are outlined and the c r i t e r i a used in i t s design are given. Operation of the pipeline and reservoir systems, and scheduling, the 3 procedure for deciding when to apply water to a crop are described. Some minor conflicts for water use were evident and these are described together with suggestions for managing the water supply to minimize such conflicts i n the future. 4 CHAPTER II VERNON IRRIGATION DISTRICT GENERAL DESCRIPTION The Okanagan Valley i s a dry valley i n the south-central interior of B r i t i s h Columbia (Figure l ) . Summers are warm and dry and winters are cool and moderately dry. Historically, the main industry has been agriculture although i n recent years tourism has become increasingly important. Since the climate i s so dry, i r r i g a t i o n i s required for almost any form of agriculture in the valley. The Vernon Irrigation D i s t r i c t (referred to as V.I.D. in this thesis) l i e s at the north end of the Okanagan Valley. I t encompasses a total of 27,400 acres of which approximately 9200 acres were registered for tax purposes as being irrigated i n 1971. The irrigated lands l i e generally along the east-west Coldstream Valley and the north-south valley which leads from the Columbia-Fraser watershed boundary in the north to Okanagan and Kalamalka Lakes in the south. The altitude of irrigated lands varies from 1200 to 2100 feet. High, tree covered terrain extends beyond the steep-sided valleys both north and south of the D i s t r i c t to an elevation of about 6000 feet. Since precipitation increases with elevation while evaporation decreases with elevation, most of the run-off originates from the higher levels. Most of the run-off comes from snowmelt and as a result peak flows occur i n May and early June, Excess water i s stored i n Haddo, Aberdeen and King Edward 5 KEY MAP Fig. I OKANAGAN BASIN IN BRITISH COLUMBIA. Lakes which l i e to the south of the D i s t r i c t at an elevation of 4000 to 4500 feet. The stored water i s released to meet i r r i g a t i o n needs later i n the i r r i g a t i o n season when the demand exceeds the unregulated flow from the remainder of the watershed. Although Irrigation i s required for most crops, precipitation (which i s higher in the D i s t r i c t than elsewhere i n the Okanagan Valley and much higher than i n the southern portion of the valley) i s sufficient to permit some crops such as hay, to grow without i r r i g a t i o n . CLIMATE With an average of 150 frost free days a year, Vernon at lattitude 50° 15' north, l i e s at the approximate northern l i m i t for the commercial growing of tree f r u i t s In the interior of B r i t i s h Columbia. The climate i s mild continental with warm summers, cool winters, and low annual precipitation. Cold spells of below zero temperatures may be expected every winter with below freezing temperatures occurring between mid-September and mid-May, though prolonged periods of extreme cold are rare. The following table gives an indication of the climatic conditions of the area. 7 TABLE I CLIMATIC DATA Vernon Vernon (Coldstream) Elevation in feet 1383 1582 Average January Temperature 23°F 21°F Average July Temperature 68°F 66°F Average January Precipitation 1.7" 1.5" Average July Precipitation 1.0" 1.2" Average Annual Precipitation 15.5" 15.1" Average Frost Free Days 151 147 The proportion of the land devoted to various agricultural a c t i v i t i e s varies from year to year but the following table taken from "Farming i n the Vernon Irrigation D i s t r i c t " (l4), gives an indication of the relative importance of the various crops 0 8 TABLE II LAND USE UNDER IRRIGATION CROP TOTAL ACRES ACRES PERCENT OF CROP PERCENT OF TOTAL IRRIGATED AREA Fruit- 2553 2519 99 37 Vegetables 709 707 100 10 Grain II65 312 27 5 Hay 3265 I887 58 27 Pasture 3337 1097 33 16 Other 6551 366 6 5 Total 17,580 6888 Of a total of 6888 acres irrigated, 3268 acres comprised grain, hay or pasture with a low Irrigation water requirement compared to tree f r u i t s . This, along with higher precipitation and lower evaporation, accounts for the fact that Vernon Irrigation D i s t r i c t has a lower total annual water demand than d i s t r i c t s i n the south Okanagan Valley where tree f r u i t s form a higher proportion of the total crop, HISTORY In I892, the Earl of Aberdeen purchased the Coldstream Ranch from the Honorable Forbes George Vernon, His intention was to develop the land by bringing i r r i g a t i o n water to i t and then s e l l the improved 9 land to settlers. It can be said that this was the beginning of commercial f r u i t growing i n the Okanagan. Irrigation was actually- instituted by the Honorable Couttes-Marjorie Banks, manager of the Coldstream Ranch, who employed Mr. F. B. Kirby, B.C. Land Surveyor to survey a ditch for irrigation of part of the Ranch, This ditch was constructed and expanded in later years to serve lands further down the valley. I t became known as the North Ditch and was s t i l l in use i n I965. The Coldstream Estate Company was formed to develop and to s e l l the irrigated land. Another Ranch manager, Mr. Ricardo, developed the Orchard Ditch, King Edward, Abbotsford and Walker systems from l o c a l sources of water—mostly diversions of Coldstream Creek (Figure 2 ). In 1905, Mr. Ashcroft was engaged to survey the Duteau Creek watershed to determine the f e a s i b i l i t y of using i t for i r r i g a t i o n supply purposes. On his recommendation, the canals now known as the Grey and South Canals were subsequently constructed along the north and south sides of the Coldstream Valley, For the control and ownership of this new system, which was to serve the lands east of the B.X, Creek, The White Valley Power and Irrigation C- was formed, the shares in this company being :ginall; i the Coldstream Estate Company. By an arrangement with the Land and Agriculture Company, the Grey Canal was extended west and north, and f i n a l l y across the Swan Lake Valley to Goose Lake in 1910, and north and south from there to eventually s p i l l excess water into Okanagan Lake in 1914. By 1915, approximately $423,000 had been spent on the system,  1 1 the operating loss that year was $ 1 2 , 0 0 0 , and the system was badly i n need of repair. On the advice of Mr. E. A. Cleaveland, Comptroller of Water Rights, the land owners petitioned the provincial government to form an improvement d i s t r i c t under the Water Act. As an improvement d i s t r i c t , the area would be e l i g i b l e for provincial assistance for improving the water distribution system. The petition was granted and in 1 9 2 0 the area was formed into a d i s t r i c t and named the Vernon Irrigation D i s t r i c t . Under the Water Act, the Lieutenant Governor in Council has the power to incorporate an area into an improvement d i s t r i c t by Letters Patent. An improvement d i s t r i c t i s a public corporate body and may have a l l the powers necessary to carry out i t s objectives. Among i t s powers are the power to sue and be sued, to borrow money, to issue bonds, to levy and c o l l e c t taxes and t o l l s , and to construct and maintain works for the distribution of water. The powers of the d i s t r i c t are exercised by Trustees who are elected by the landowners in the d i s t r i c t . Since incorporation i n 1 9 2 0 , the Vernon Irrigation D i s t r i c t has passed through several periods of hard times, Mr. G. C. Tassie was engaged as General Manager in 1937» a n d- under his guidance a program of more permanent works was instituted. However, lack of funds prevented any major program of rehabilitation, and only the more c r i t i c a l parts of the system received attention. Between 19^5 and 1 9 6 3 , repairs included l i n i n g of parts of the canal system with concrete slabs to prevent seepage, replacement of steel flumes, and laying of some asbestos- cement pipe. 12 In general, up u n t i l construction of the new system commenced in 19^5» lack of money prevented any but the most urgent repairs and replacements from being made. In l Q 6 l , the federal government passed the Agricultural and Rural Development Act (A.R.D.A.). This act states that the minister may, with the approval of the Governor i n Council, enter into an agreement with any province providing for the joint undertaking of projects for the development of income and employment opportunities i n rural areas. Included are projects for the development of water supplies for agricultural or other rural purposes and projects for the more e f f i c i e n t use and economic development of rural lands, Under this agreement, project costs are divided equally among the provincial and federal governments and the landowners in the benefiting area. When, in 19&2, the Vernon Irrigation D i s t r i c t manager resigned, the d i s t r i c t trustees decided to try to operate the d i s t r i c t without an i r r i g a t i o n manager. An engineering consultant who was called i n to assi s t in the operation of the system, suggested that a renewal program be instituted. The trustees went to the Department of Lands, Forests, and Water Resources to obtain assistance i n planning. The Water Investigations Branch carried out a study of the V.I.D. in 1964 and I965, under the A.R.D.A. agreement with the assumption of A.R.D.A. financing. In I965 a report was prepared which compared the f e a s i b i l i t y of rehabilitating the old system with the construction of a completely new pipeline system,, The study considered only the water distribution system although the application method was a consideration in design. The study was quite comprehensive since, to quote the report, "any decision to adopt an alternative which involves abandoning works that have successfully provided irrigation water to the Di s t r i c t for over f i f t y years, should not be made before an alternative of improving the existing system i s carefully scrutinized" (5). Although the study dealt mainly with the rehabilitation of the ditch system and the construction of a pipeline system, other alternatives considered in the study were j 1, pressurization of the existing system 2. canalization of Coldsteam Creek 3. pumping from Okanagan, Kalamalka, and Swan Lakes 4, pumping from Okanagan Lake to supply the Belle Vista area These alternatives posed problems of screening, blockage of sprinklers, high cost of pumping schemes compared to gravity, and generally higher costs than rehabilitating the ditch system or construction of a buried pipeline system. Therefore, no extensive consideration was given to the alternatives l i s t e d above, and instead, the study concentrated on the alternatives of rehabilitating the ditch system and providing a new pipline system. The main points considered in the study are outlined i n Chapter III, The pipeline system was chosen and between 1965 and 1970» the Vernon Irrigation D i s t r i c t gradually changed to the pipeline system. In 1971 the D i s t r i c t operated entirely without delivery ditches. 14 OPERATION OF THE OLD IRRIGATION SYSTEM The old distribution system of the Vernon Irrigation D i s t r i c t , parts of which were in use u n t i l 1970, consisted of some 57 miles of open canals and about 37 miles of distribution pipeline. Most of i t was constructed between 1900 and 1920 or before the D i s t r i c t was incorporated. Water was regulated by storage and release from Aberdeen and Haddo Lakes. After release from Haddo Lake, the water flowed down Duteau Greek to the Vernon Irrigation D i s t r i c t diversion at which point the water entered the Grey Canal at the approximate elevation of 2150 feet. From the canal, the water was conveyed by syphon and flume to the irrigators land. The farmers had to order water for irr i g a t i o n at least twenty- four hours i n advance of the desired delivery time. The water was ordered from the Water B a i l i f f who i n turn ordered the water from the Chief Water B a i l i f f . The Chief Water B a i l i f f added up a l l the water required for a l l the areas, added an amount for seepage losses, and ordered the dam operator at Haddo Lake to open or close the control as required to supply the estimated amount. The amount of excess water ordered to satisfy seepage losses was in the order of 30 per cent. Regulation of water was generally by means of gates and valves located along the canal. The morning that the irrigat o r was to receive water, the Water B a i l i f f arrived to open the control at the 15 farmer's outlet. This control was the property of the D i s t r i c t and only employees of the D i s t r i c t were permitted to adjust i t . Irrigators paid only for water actually used hy them, and i t was measured by means of weirs or gates or by calculation from sprinkler nozzle sizes and supply pressure. There were problems with this type of measurement as sometimes the measuring flumes were t i l t e d by frost action or blocked by debris from the canal. When the frost action occurred, i t was necessary to recalibrate the flume, whereas i n the case of debris blockage, the D i s t r i c t was usually obliged to extend the period of flow to make up for the reduced discharge rate. Twenty-four hours before the farmer finished i r r i g a t i n g , he would again c a l l on the Water B a i l i f f to shut off the water. The farm irrigation systems in the Vernon Irrigation D i s t r i c t consisted mainly of furrow irrigation in which the f i e l d had furrows constructed with gentle slopes to prevent erosion. The irr i g a t o r allowed water to flow down a furrow u n t i l the ground had enough moisture, then sealed off that furrow and transferred the flow to the next furrow. This operation was repeated u n t i l the f i e l d or farm was irrigated. The farmer had no s c i e n t i f i c method of knowing when the land was suffi c i e n t l y moist, but re l i e d on his experience and knowledge of the physical characteristics of his own s o i l — t h e f e e l , look and smell of i t . If insufficient water were applied to the crop, consequences ranged from sub-optimal growth to permanent wilting and loss of the crop. Therefore, i t was natural that the irrigator would try to apply 16 more water than necessary in order to have a safety margin. This safety margin was also good from the point of view of s a l t build-up as s a l t concentrations may build up to levels toxic to the crop, i f insufficient drainage water passes through the root zone. Therefore, some application of irrigation water over and above that required for consumptive use i s desirable to leach soluble salts from the root zone. For the Okanagan, leaching requirements are f a i r l y modest and i t i s generally considered that over winter precipitation i s almost sufficient to leach undesirable salts from the root zone. 17 CHAPTER III NEW IRRIGATION SYSTEM DESIGN In order to take advantage of the opportunities offered under the Agricultural and Rural Development Act, the trustees of the Vernon Irrigation D i s t r i c t requested the Department of Lands, Forests, and Water Resources to carry out a study to determine the best method of rehabilitating the irrigation system. This was done and i n the report, which was published i n 19&5» two main alternatives were examined. The f i r s t involved replacement of a l l components in the existing system with a remaining l i f e of less than twenty-five years and l i n i n g the canals. The second scheme involved a new system consisting entirely of pipeline buried below the frost l i n e . The supply pressure would be supplied generally by gravity, but some pumping would also be involved. Comparison of Alternatives The estimated annual cost per acre over twenty-five years was twenty-three dollars for reconstructing the ditch system and twenty- eight dollars for the new pipeline system. Despite the cost difference, the pipeline system was chosen. The main reasons for the choice of the pipeline are outlined in the following paragraphs, 1, Rebuilding the old system would mean that the area was s t i l l served by a f i f t y year old system. 18 2, The ditch system was designed for furrow ir r i g a t i o n which depended on a pl e n t i f u l supply of cheap labour. Many farmers had changed to sprinkler i r r i g a t i o n and the trend appeared to be toward an increase i n sprinkler i r r i g a t i o n and a decrease i n furrow i r r i g a t i o n . With the ditch system, many small pumps would be required for sprinkling and i f the cost of pumping were added to that of rebuilding the ditches, the total would be much more than the cost of supplying the water under pressure i n the pipeline. In other words, the total cost of supplying water to the sprinklers would be less with the pipeline conveyance system than with the ditch system, 3. A ditch system i s subject to the ingress of debris and weeds which tend to clog sprinkler heads unless screening i s undertaken at the intake. With the pipeline system, debris could be removed by one set of screens at each intake, whereas, with the ditch system, each ir r i g a t o r would require a set of screens, 40 The new system would be constructed of long lasting components not exposed to frost or other mechanical damage and hence should have low maintenance costs, 5« The water losses of about JO per cent, due mainly to seepage from canals, would be reduced to almost n i l with the construction of the pipeline system. The water saved i n this way was estimated to be enough to irrigate 1500 to 2000 additional acres. 6. During the rehabilitation of the old system, a l l components 19 with a useful l i f e of twenty-five years of less would be replaced. After that time, further expenditures would be required. The pipeline system should not require significant capital expenditures for f i f t y years, In summary, i t was f e l t that, from a long term point of view, the pipeline system offered the cheapest and best i r r i g a t i o n service. With the pipeline system, the area could also be served with chlorinated water at l i t t l e additional cost. This was an important consideration as many areas were serviced with shallow wells which probably derived a large amount of recharge from the seepage losses from the canals. The rehabilitation of the system would have tended to reduce seepage which could have perhaps resulted i n dry wells. Design Cr i t e r i a for the Pipeline System Duty. The water sales records of the Vernon Irrigation D i s t r i c t were studied by the Water Investigations Branch to determine the so-called 'duty' of water for the D i s t r i c t ( i . e, the total depth of water application in a season). It was found that there had been a slight decline i n total water demand over the years between 1950 and 1963 and this was attributed to the increase in sprinkler i r r i g a t i o n and the associated increase in application efficiency. The maximum duty of water between 1953 a r^d 1963 w a s calculated to be an average of 15.O inches over the irrigated area. In 1959* a, s o i l survey of the North Okanagan Valley was undertaken by the Soil Survey Branch, B r i t i s h Columbia Department 20 of Agriculture. The Vernon Irrigation D i s t r i c t was divided into s o i l s areas to compare the water requirements. Tree f r u i t i r r i g a t i o n demands are higher than those for other types of crops. Therefore, to obtain a maximum figure for water requirements of the area, tree f r u i t demands were used i n the calculations. An average duty of 18,3 inches was calculated. The large difference with the 15.0 inch figure calculated from records was accounted for by the fact that large areas such as those growing grain and hay crops were l i g h t l y irrigated, thus bringing down the overall average. For design purposes, the duty assumed by the Water Investigations Branch was an average of 16 inches. Maximum demand rate. From the D i s t r i c t records i t was •.. calculated that the average maximum demand rate for the hottest sixteen day period (July 16 to 31) was 4,2 U.S. gallons per minute per acre. The actual design rate would have to exceed the average maximum demand rate to meet requirements of areas with above average maximum demand rates and to meet instantaneous peaks. However, a continued decrease in furrow irrigation would tend to reduce the maximum demand rate. Based on s o i l and consumptive use requirements, the maximum demand rate was calculated to 5*6 U.S. gallons per minute per acre. Using these figures as a guide, the Water Investigations Branch decided to use 6.0 U.S. gallons per minute per acre for the re h a b i l i - tation of the ditch system and 5*0 U.S. gallons per minute per acre for the pipeline system for purposes of comparing the two systems. The p i p e l i n e scheme would supply water under pressure and i t was assumed t h a t w i t h i t , s p r i n k l e r i r r i g a t i o n would be adopted throughout the D i s t r i c t w i t h a r e s u l t a n t l o w e r i n g of the maximum demand r a t e . As d e s c r i b e d i n the previous s e c t i o n , the p i p e l i n e system was chosen. The f i g u r e of 5 U.S. g a l l o n s per minute per acre was r e t a i n e d as a de s i g n c r i t e r i a n . P r essure. The p i p e l i n e system was designed to provide 100 f e e t of head of water a t the o l d c a n a l l e v e l . This pressure would be s u f f i c i e n t t o i r r i g a t e by s p r i n k l e r s a l l l a n d f o r m e r l y served by g r a v i t y from the o l d system. OPERATION OF NEW IRBIGATION SYSTEM D i s t r i b u t i o n System The Vernon I r r i g a t i o n D i s t r i c t system i s now a newly renovated system c o n s i s t i n g of approximately nineteen m i l e s of 50 i n c h to 24 i n c h concrete and s t e e l pipe i n the main l i n e ( F i g u r e 3 )• Branch l i n e s s e r v i c e each area w i t h l a t e r a l s and o u t l e t s d e l i v e r water t o each farmer. The water i s r e l e a s e d from the dam a t Haddo Lake and fl o w s approximately f i f t e e n m i l e s down Duteau Greek. A t t h i s p o i n t a s m a l l d i v e r s i o n dam has been c o n s t r u c t e d which impounds about t h i r t y a c r e - f e e t when f u l l . This r e s e r v o i r i s s u f f i c i e n t to supply the d i s t r i c t f o r f o u r hours and twenty minutes a t maximum demand r a t e of 38,000 U.S. g a l l o n s per minute. Water i s screened before i t enters the main i n t a k e p i p e . The i r r i g a t i o n water from t h i s p o i n t i s  delivered through a completely closed system. 23 Similarly, water released from King Edward Lake flows down Deer Greek and passes into the system at a small diversion. There i s very l i t t l e storage at this diversion, so releases from King Edward Lake are controlled very carefully to avoid wastage. At the irrigators' delivery point, the D i s t r i c t maintains two valves; both are below frost l i n e . One opens the line into the stand- pipe and the other drains the stand-pipe. At the upper end of the stand-pipe i s the farm valve owned and maintained by the ir r i g a t o r . In the spring when the farmer i s ready to start i r r i g a t i o n , he c a l l s the D i s t r i c t and requests that his water be turned on. An employee of the D i s t r i c t then proceeds to close the drain valve and open the main valve. From this time to the end of the ir r i g a t i o n season, the farmer has water "on tap". He may use the water for the length of time he wishes—only the maximum rate i s fixed. The maximum rate of application for the d i s t r i c t as a whole of 5 U.S. gallons per minute per acre was determined as described i n the previous section. This rate also applies to the farmer's individual i r r i g a t i o n system. Each system i s thus designed to use water at a rate calculated on the basis of 5 gallons per minute per acre over the whole acreage. In practice the water i s applied at a much greater rate at any one time, the area which must be irrigated at any one time depending on the safe ir r i g a t i o n interval which in turn, depends on the water holding capacity of the s o i l and the consumptive use. For example, i f a farmer had a twenty acre plot with a safe interval of ten days, his system would be designed to deliver (20 x 5) 100 gallons per minute , and this would be applied to two acres at a time i f he operated on a one day cycle or one acre at a time i f he operated on a twelve hour cycle. Thus, the farmer requires sufficient equipment to enable him to irrigate at least one acre at a time. The larger the spread of the equipment, the less frequently i t has to be moved. In order to control the application rate under varying pressure conditions, the D i s t r i c t requires that a flow control valve be placed under each sprinkler head. The flow control valves used i n the Vernon Irrigation D i s t r i c t (Dole type) consist of a metal cylinder with a rubber diaphragm inside i t . In the rubber diaphragm i s a hole arranged such that, as the pressure increases, the size of the hole decreases and the flow decreases. I f the pressure decreases, the size of the hole increases, thereby allowing the flow to increase. In order to encourage i t s policy concerning flow control valves, the D i s t r i c t supplies them to the irrigators free of charge. The D i s t r i c t polices the system and the Water B a i l i f f s have the power to shut off the water i f flow control valves have been altered or removed. Operation of the system requires that the pipeline be kept f u l l at the headgates diversion at a l l times by regulation of water releases from Haddo Lake. This system requires a new s k i l l on the part of the Chief V/ater B a i l i f f i n that, since irrigators no longer are required to order water in advance, he must now be able to accurately predict the water use over the next twelve hour period. I f too much water i s ordered from the reservoir, i t w i l l s p i l l over the diversion at the headgates and be wasted. If too l i t t l e water i s ordered, the pipe w i l l empty and pressure loss at the lower end of the system w i l l prohibit i r r i g a t i o n . When determining the amount of water to order from Haddo Lake, the Chief Water B a i l i f f considers the weather, the time of year and the time of week, A change in weather from cool to warm or wet to dry would dictate an increase i n flow. The time of year indicates what the irrigators are doing with their crops. I f they are starting harvest, they w i l l be stopping i r r i g a t i o n . Variation in demand with the time of week i s a phenomenon which has developed with the new system. For example, at the Coldstream Ranch, with over 1200 acres under ir r i g a t i o n , the manager has determined that by shutting down ir r i g a t i o n during the weekend, the ranch can save money which otherwise would have to be paid i n overtime to workers moving irr i g a t i o n pipes, without risk to their crops. After balancing a l l the above factors the Chief Water B a i l i f f makes an educated guess as to the water demand and orders the water from Haddo Lake, The water takes approximately eight hours to travel from the dam at Haddo Lake to the headgates and the pond at the headgates holds enough water for about four and one-third hours at maximum demand, A delicate balance must be maintained i f water wastage i s to be kept to a minimum0 For the f i r s t year of operation, the demand at the headgates was observed to change relatively slowly and almost linearly during both the increasing and decreasing demand 26 cycle. This i s probably due to the fact that the D i s t r i c t i s so large that the variations caused by individuals are insignificant. No problems are anticipated with prediction of water demands on a daily basis. Plans have been made to i n s t a l l an automatic gate system at the lake outlet when finances permit. The water level in the headgates pond w i l l be monitored continuously and the gate operation at the lakes w i l l be radio controlled. As the level i n the headgates pond goes down, the control at the dam can be opened to release more water. This procedure w i l l ensure an adequate supply of water at the headgates while keeping s p i l l to a minimum. Also, natural flow from the uncontrolled portion of the watershed can be u t i l i z e d more readily. However, in view of the limited storage at the diversion of only about four hours supply and the time of travel of eight hours from the reservoir, very careful design w i l l be necessary. Reservoir System The Vernon Irrigation D i s t r i c t has four storage reservoirs as shown in Figure k. Aberdeen, the largest, drains directly into Haddo Lake which i s much smaller in storage volume (Table III). From Haddo Lake water i s released into Duteau Creek and after travelling about fi f t e e n miles, can be diverted into the Vernon Irrigation D i s t r i c t i r r i g a t i o n scheme at the diversion dam at Headgates,, If the water i s not diverted, i t continues down Duteau Creek and eventually into the Fraser Watershed, About seven and one half miles to the west  28 l i e s King Edward Lake 0 The water from this lake flows down Deer Creek to a diversion dam and then, i f i t i s not diverted into the irrigation scheme, this water flows into Kalamalka Lake. The l a s t storage lake i s Goose Lake, a balancing reservoir on the north-west side of the D i s t r i c t . Goose Lake has l i t t l e natural inflow but has a l i v e storage of 1275 acre-feet. TABLE III CATCHMENT AREA, STORAGE, AND GOVERNING WATER LEVELS OF VERNON IRRIGATION DISTRICT RESERVOIRS (5) RESERVOIR CATCHMENT LIVE WATER ELEVATIONS SURFACE AREAS AREA STORAGE FEET (GEODETIC) ACRES SQ. MI. AC. FT. MAX. MIN. MAX. MIN. Aberdeen Lake 20.7 8,693.6 4,196.0 4,172.0 576.2 112.0 Haddo Lake 19.2 2,498.3 4,167.1 4,146.6 176.3 30.0 King Edward Lake 4.6 1,253.5 4,485.0 4,465.0 82.3 7̂.0 Goose Lake Negligible 1,275.0 1,637.0 1,617.0 89.0 47.0 The D i s t r i c t Irrigation Manager-Engineer has the responsibility for operation of the reservoirs and the main c r i t e r i a used to operate the dams i s that there i s maximum carry over, for insurance against drought next season. At the end of the irr i g a t i o n season, the lake outlets are closed and remain closed u n t i l the beginning of the next irr i g a t i o n season (except for domestic water releases from Haddo Lake), During the spring freshet, there i s seldom sufficient run-off to completely 29 f i l l Aberdeen Lake since i t has a large storage volume in comparison to i t s watershed area. King Edward Lake sometimes f i l l s and s p i l l s but not as often as Haddo Lake which almost always s p i l l s large amounts of water. In order to use some of the spilled, water, i t i s channelled to Goose Lake through the irr i g a t i o n system and may f i l l Goose Lake before the irr i g a t i o n demand has become substantial. The pattern of reservoir releases i s as follows: during the f i r s t part of the irrigation season while the demand i s rela t i v e l y low, water i s drawn from Haddo Lake which i s r e f i l l e d from Aberdeen Lake as necessary. As the demand increases King Edward Lake i s tapped. At the peak demand of the season Goose Lake i s also opened and a l l inputs into the system are used. The ideal situation at the end of the irr i g a t i o n season i s to have Goose and Haddo Lakes empty, some carry over in King Edward Lake and as much carry over as possible in Aberdeen Lake, The above procedure i s illu s t r a t e d in Figures 5 a n ( l 6 . The hydrographs shown have been derived from recorded discharges in B.X. Greek in 19&7 since detailed records of inflow into the lakes are not available. B.X, Creek, has the same general watershed characteristics as the lakes in the Vernon Irrigation D i s t r i c t and the hydrograph shown i s believed to be reasonably representative. The vertical lines show that the reservoir i s f u l l and the inflow i s transmitted directly to outflow. For example, on May 18, (Figure 5) Haddo Lake was f u l l and the water was diverted to Goose Lake. On June 21, the outflow from the watersheds became less than the irrigation demand. Therefore, storage water had to be released to satisfy the demand. On July 15, a l l the reservoirs 30 co u.' o 5 o 6 0 1 4 0 1 2 0 100 8 0 6 0 4 0 2 0 IS 2S 3S 4S 5S 6 R 2R 3R 5R HADDO L A K E S T O R A G E KING EDWARD LAKE STORAGE GOOSE L A K E S T O R A G E GOOSE L A K E STORAGE A B E R D E E N L A K E STORAGE SPILL FROM KING EDWARD L A K E HADDO L A K E R E L E A S E KING EDWARD L A K E RELEASE GOOSE L A K E R E L E A S E ABERDEEN LAKE RELEASE ABERDEEN L A K E C A R R Y - O V E R I300ac . f t . HADDO,KING EDWARD AND ABERDEEN L A K E S HADDO AND KING EDWARD LAKES RRIGATION DEMAND HADDO LAKE MARCH APRIL MAY JUNE JULY AUGUST SEPTEMBER Fig.5 HYDROGRAPHS OF LAKE INFLOW AND RELEASE IN HIGH FLOW YEAR . 31 6 0 140 _ 120 to u. (J _ 100 ? o _ i u. 8 0 6 0 - 4 0 - 2 0 IS 2S 3S 4S 5S HADDO LAKE STORAGE KING EDWARD LAKE STORAGE GOOSE LAKE STORAGE GOOSE LAKE STORAGE ABERDEEN LAKE STORAGE HADDO LAKE RELEASE KING EDWARD LA K E RELEASE GOOSE LA K E R E L E A S E ABERDEEN L A K E R E L E A S E R E L E A S E OF ABERDEEN LAKE CARRY - OVER HADDO, KING EDWARD AND ABERDEEN LAKES IRRIGATION DEMAND HADDO AND KING EDWARD LAKES MARCH APRIL MAY JUNE JULY AUGUST SEPTEMBER F i g . 6 HYOROGRAPHS OF LAKE INFLOW AND RELEASE IN LOW FLOW YEAR . were contributing to the peak irrigation demand. 32 During any one year, the total demand might be larger than the total inflow to the lakes. The carry over from the previous year would then be used to satisfy the demand (Figure 6 ). In the year illu s t r a t e d in Figure 5 the total demand was less than the total inflow so there was carry over for the next year. 33 CHAPTER IV SCHEDULING THE APPLICATION OF WATER Scheduling of irr i g a t i o n means the application of the correct amount of water at the time when i t i s needed by the s o i l (17). The objective of scheduling i s to maintain the s o i l moisture content within an optimal range, while applying as l i t t l e water as possible. Since scheduling offers one of the main opportunities for economising on the use of water, i t i s considered i n some detail i n the following sections. EQUIPMENT USED IN SCHEDULING The most common method of scheduling used i n the Okanagan Valley was evolved by Dr. Wilcox, of the Summerland Research Station who named i t the "Balance Sheet" method. The equipment for this method consists of a balance sheet (Figure 7 ), a rain gauge and an evaporimeter. The Black Belanni Plate evaporimeter, (Figure 8) was introduced to Canada i n 1957 a n d met a l l but one of the requirements for use i n the Okanagan? i t uses water as an evaporating medium and the water froze i n the spring and f a l l as the temperature dipped at higher sites along the valley wall. The evaporimeter was sometimes damaged, and the records were lo s t for the period while the evaporimeter was frozen. Dr. Wilcox developed an evaporimeter especially for use in the Okanagan Basin and termed i t the "Ogopogo" evaporimeter Figure 7. BALANCE SHEET Grower: John Doe Month: May, 1964 Safe Irrigation Interval: 6 days Credit Depth: 1.68 inches Date Water Use Rain Credit Depth Balance i 1 .20 1.68 1.48 Started irrigating 7 a.m. 2 .24 1.24 3 .25 .99 4 .19 .80 5 .19 .61 6 .25 .36 Finished irrigating 7 a.m. 7 .18 .16 .34 8 .23 .11 9 .26 1.68 1.42 Started irrigating 7 a.m. 10 .16 .20 1.42 Raining 11 .08 .23 1.42 Raining 12 .10 .15 1.42 Raining 13 .18 .06 1.30 14 .28 1.02 Finished irrigating 7 a.m. 15 .23 .79 16 .10 .50 1.02 (Rainfall credited to balance on May 17 .22 .80 1*) 18 .30 .50 19 .30 .20 20 .30 -.10 Stopped for mowing 21 .25 1.68 1.33 Started irrigating 7 a.m. 22 .30 1.03 23 .28 .75 24 .25 .50 25 .26 .24 26 .27 -.03 Finished irrigating 7 a.m. 27 .20 1.68 1.45 Started irrigating 7 a.m. 28 .15 1.30 29 .20 1.10 30 .20 .90 31 .25 .65 Balance of .65 carried over to June 35 (Figure 9) (l6). The evaporating surface i s the end of a cyl i n d r i c a l carborundum block approximately 5 c m « i n diameter and 6.6 cm. long which has been placed in a bottomless polyethylene bottle. A tube leads from the bottle to the reservoir which has a capacity sufficient to supply the evaporimeter with l i q u i d for the period between readings. A glass shield ten to twelve inches in diameter i s placed three inches above the evaporating surface to protect i t from rain. The evaporating l i q u i d used i s a mixture of methanol and d i s t i l l e d water which does not freeze u n t i l the temperature reaches about 10°F. The rain gauge may be of any type, but the commercially made wedge-shaped plastic model i s the most popular. GENERAL PROCEDURE When the irri g a t i o n i s started, the appropriate credit depth i s added to the balance on the sheet. Each day thereafter, the balance sheet i s debited with the amount of water used by the crop which i s estimated from the evaporation measured by the evaporimeter. If the irrig a t i o n cycle i s completed before the balance on the sheet reaches zero, the sprinkler lines are shut down and l e f t idle u n t i l the balance reaches zero. At this point, the next irrigation i s started and the balance sheet credited with the amount of water applied. The balance sheet shown (Figure 7) i s for a plot of land with an irrigation interval of six days and a credit depth of 1,68 inches. The depth of application would be determined by multiplying the credit depth by a factor which accounts for the application efficiency. In Figure 8 . B e l l a n i Plate Evaporimeter Figure 9 « Ogopogo Evaporimeter the i l l u s t r a t i o n , i r r i g a t i o n was begun on panel one on the f i r s t of May. This i s the panel for which the s o i l moisture balance was kept. The farmer then added the 1.68 inches to the previous balance, subtracted the water use or evapotranspiration for that day, and entered the balance (i.48). Irrigation continued with the lines being changed every twelve hours and, each day, the water use was subtracted from the previous balance to show how much water was l e f t i n the s o i l i n panel one. At the end of the sixth day, one i r r i g a t i o n cycle was completed and the balance sheet showed that there was s t i l l moisture (O.36") in the s o i l . The system was shut down and the ir r i g a t o r waited u n t i l the balance sheet reached an amount approximately equal to the daily water use, whereupon he started i r r i g a t i n g again. CREDIT FOR RAIN When rain occurs, any unsaturated panel benefits, but can only hold additional water up to f i e l d capacity. When a panel i s irrigated, i t s moisture content i s raised to f i e l d capacity, and therefore, rain occurring on that same day can be counted only up to the amount of evapotranspiration occurring while the panel i s being irrigated. In order to take f u l l advantage of rain, a budget would be needed for each panel i n the f i e l d . In practice, however, a budget i s kept for only one panel of the f i e l d rather than each individual panel. Therefore, an elaborate set of rules has evolved to ensure that the f i e l d does not dry to the point where crops are damaged. With this system, i f ir r i g a t i o n i s 38 i n progress, credit i s only given for rain up to the evapotranspiration for the day; any more credit could cause an unwarrented delay i n starting the next ir r i g a t i o n which could result i n excessive drying of the s o i l at some point in the f i e l d during the next i r r i g a t i o n . When no ir r i g a t i o n i s i n progress, credit for rain can be given only up to the balance on the sheet at the time when the l a s t i r r i g a t i o n cycle was completed. Between irr i g a t i o n cycles the whole f i e l d receives benefit from the rain. The wettest part of the f i e l d receives the least benefit; in fact, only up to f i e l d capacity at that point. The wettest part i s , of course, the s o i l at the l a s t point irrigated, and f i e l d capacity there i s represented by the balance at the f i r s t setting, as shown on the balance sheet at cessation of ir r i g a t i o n . Giving more credit than this for rain could cause an unwarrented delay in the start of the next ir r i g a t i o n ( 1 9 ) , These rules are il l u s t r a t e d on the balance sheet (Figure 7 ) . On the tenth, rain amounted to 0.20 inches, 0,04 inches more than the evapotranspiration. Even so credit for that rain could be given only to the balance on the previous day, (1.42") as irr i g a t i o n was i s progress. The same applies to the rain which occurred on the eleventh and twelfth. On the sixteenth, i r r i g a t i o n was not i n progress and rain occurred. Credit for this rain was given up to the level or balance on the day that i r r i g a t i o n ceased (l,02). 39 CHOOSING A SITE FOR THE EVAPORIMETER Evapotranspiration from a small irrigated plot is greater when the plot is surrounded by dry unirrigated land than when i t is in the middle of a large irrigated area. This is due to the advection of heat from the surrounding dry land and is sometimes referred to as the "oasis effect". In the Okanagan, a high proportion of the irrigated land abuts or lies close to dry land and in these circumstances placing the evaporimeters in the centre of the irrigated land would give readings too low to represent the very long marginal areas. Evaporimeters placed on dry land often show much higher rates of evaporation than those placed within an irrigated area and hence cannot represent conditions over the irrigated land satisfactorily. A reasonable compromise is a site chosen near the edge of the irrigated land where i t adjoins dry land or in a small non-irrigated plot within the irrigated area. In any case, the evaporimeters must be placed where they do not receive water from the sprinklers. SCHEDULING FOR IRRIGATION DISTRICTS Some Irrigation Districts operate evaporation stations for the use of irrigators throughout the district. In this case the evapori- meters must be located so that the readings will represent the driest irrigated area within the district. This means that some orchards will receive excess water, but at least a l l orchards should receive enough. The problem of orchards receiving too much water can only be solved by installing more evaporimeters. 40 The D i s t r i c t evaporimeters are read by an employee and the water use figures are posted on a bulletin board on the side of a road travelled frequently by the irrig a t o r s . Irrigators copy the figures and keep the balance sheet for their own orchards. One improvement which might be applied to the system i s the install a t i o n of an automatic telephone answering service. The evaporation readings could be read into a tape recorder and irrigators would only need to d i a l the appropriate telephone number to obtain the evapotranspiration figures, which they need to keep their own water balance. ADVANTAGES OF SCHEDULING The main advantage of scheduling i s that i t permits maximum use of the available water resources. Other benefits include: 1. Water wastage i s reduced to a minimum which results i n lower pumping costs, reduced seepage and less leaching of nutrients from the s o i l . 2. Less time i s spent i r r i g a t i n g ; this saving i n time may amount to as much as 10% i n the Vernon area, 3. In cool or rainy weather, irr i g a t i o n can be discontinued without fear of damage to crops due to lack of water, 4. As the same amount of water i s applied at each i r r i g a t i o n , the design features of the system may be standardized (nozzle size, pressure, length of set). 5. The irr i g a t o r can have greater confidence and peace of mind knowing his crop w i l l not suffer because of lack of water. Before the advent of scheduling, some irrigators shut down during wet or cool weather "but they worried about the damage that could occur i f they did not start i r r i g a t i n g soon enough. With scheduling, they can be confident that no damage w i l l result to their crops. PROBLEMS WITH SCHEDULING Scheduling as i t i s practised, using a simple budget for a farm rather than a budget for each panel involves the assumption that the weather remains constant or changes only gradually. Weather however, i s not always so co-operative and some wilting of the crop can occur i f precautions are not taken (Figure 10'),. As an example, assume that an orchard requires two inches of water every ten days i n the heat of summer. This means that the average peak evapotranspiration i s 0 .20 inches per day. I f during cool weather i n June, the average evapo- transpiration happens to be only 0.10 inches per day the grower who l s using the balance sheet procedure finishes his ir r i g a t i o n and waits for ten days before starting to irrigate again. I f the weather then turns hot and the average evapotranspiration becomes 0 ,20 inches per day, by the time the l a s t part of the orchard i s irrigated, the s o i l there contains 1.00 inch less water than i t had the l a s t time when i t was irrigated and the s o i l water d e f i c i t now i s 3.00 inches. I f the s o i l i s now given the standard application of two inches, a d e f i c i t of one inch w i l l remain. The d e f i c i t can be cumulative over the irrigation season and could build up to the point where the crops could be permanently damaged. In order to avoid this d i f f i c u l t y the rule was developed that i r r i g a t i o n must be started when the available water content at the starting point f a l l s to 60%, In the example cited this TEMPERATURE BELOW AVERAGE PRECIPITATION ABOVE AVERAGE TEMPERATURE ABOVE AVERAGE 0 . 3 0 cn to £. U 1 0 . 2 0 UJ o o o o o o o O o o o o o oo o o o o oo O 00 O O o o o o o o o o O 000 o o o o 0 .10 o o o o o o o o o o 00 o 00 o oo O o 00 o coo O o o 00 o o o o o o o oo o oo o o oo o oo o o o o o °u ° 00 o o o o o o o o 00 o o o o o o 00 o o| o J. May I 15 June I 15 July 1 15 August I 15 September I 15 •p- F i g . 1 0 D A I L Y E V A P O T R A N S P I R A T I O N A T S U M M E R L A N D R E S E A R C H S T A T I O N , 1 9 7 1 . 43 would allow the water content just before ir r i g a t i o n to f a l l to as low as of the s o i l moisture storage, a value which does not seem to damage f r u i t trees, although shallow rooted cover crops may wi l t occassionally, USE OF SCHEDULING Although the "Balance Sheet" method of scheduling has been developed to a very sophisticated state, relatively few of the growers i n the Okanagen Valley are using i t . Some growers have their own set procedure which they f e e l i s satisfactory, and they see no need for change. Some are not suited by temperament or education to the keeping of balance sheets and regulating their irrigation accordingly. Perhaps some irrigators f e e l that a plentiful supply of water i s a natural right inherited from their forefathers and see no need for conservation. Some, certainly, are not aware of the need for conservation nor of the a v a i l a b i l i t y of scheduling procedures. Also, the present "tax" method of payment for ir r i g a t i o n service does not encourage farmers to save water since under this system farms for which water service i s maintained, must pay a f l a t rate whether of not the maximum allowable water i s used. The minimum requirement of an irr i g a t i o n system i s that i t i s designed to cover the f i e l d with sufficient i r r i g a t i o n water during the one or two weeks of hottest weather i n summer. Some growers turn on the water i n the spring and run their system a l l season at the maximum rate. Therefore, for most of the year, water i s being applied at a rate in excess of the evapotrans- piration rate. This water as well as being wasted, leaches nutrients 44 such as nitrogen and boron from the s o i l , nutrients which not only are expensive to replace but also can cause water quality problems i n the water down stream from the irrigator's f i e l d . The cost of setting up an individual evaporimeter station in 1971 i s less than $50*00 and Department of Agriculture and Summerland Research Station personnel are always available and willing to assist with the in s t a l l a t i o n . At the time of writing evaporimeters were supplied from the Research Station and rain gauges were obtained loca l l y from a commercial source. 45 CHAPTER V ADDITIONAL USES OF DUTEAU CREEK FISHERIES Paxt of Duteau Creek, "below the Vernon Irrigation D i s t r i c t diversion, provides a spawning and rearing area for Pacific Salmon (Figure 11). As many as two thousand Chinook have been known to spawn i n Duteau Creek ( 2 3 ) . A constant supply of clean water i s c r i t i c a l i n the l i f e cycle of the salmon. The adults lay their eggs i n gravel on the creek bed i n the f a l l of the year. It i s necessary to have an adequate flow of water over the gravel so that the eggs w i l l be provided with enough oxygen through the winter. In the spring, the eggs hatch and the young f i s h remain i n the fresh water system for one year and then they migrate to the ocean. When they are three to seven years old, the salmon return to the stream from which they originated, to spawn and die. During the spawning season, enough water must be provided to allow the f i s h to swim and spawn. If the f i s h population i s to be maintained there must be a year round supply of water below the Vernon Irrigation D i s t r i c t diversion (Figures 12 and 13 ). The old V.I.D. diversion dam i s reported to have leaked badly enough so that sufficient water escaped down stream to maintain the f i s h population. With the erection of the new watertight diversion dam, the water w i l l have to be released i f the f i s h population i s to be maintained. The Canada Department of Fisheries 46 F i g . I I F L O O D I N G A N D S P A W N I N G L O C A T I O N I N D U T E A U C R E E K W A T E R S H E D . Fig. 12 DISCHARGE IN DUTEAU CREEK BELOW THE VERNON IRRIGATION DISTRICT DIVERSION, LOW FLOW YEAR , 1963 . 18 23 28 3 8 13 18 23 28 3 13 23 3 13 23 3 13 23 3 13 APRIL MAY JUNE JULY AUGUST SEPTEMBER Fig.13 DISCHARGE IN DUTEAU CREEK BELOW THE VERNON IRRIGATION DISTRICT DIVERSION, HIGH FLOW YEAR . 49 i n Vancouver estimated flow requirements at 4.0 c f s . during non-spawning periods while 7.0 c f s . are required for four months (September through December) during spawning,. (23). This amounts to 36OO acre feet per year which represents 26% of the total storage capacity of Vernon Irrigation D i s t r i c t . FLOOD PROTECTION AT LUMBY Approximately seventeen miles east of Vernon i s the small town of Lumby, where the main economic a c t i v i t i e s are cattle ranching and wood processing. The town has suffered i n the past from flood damage from the combined effect of high flows i n Bassette and Duteau Creeks. The main concern has been the loss of employment for approximately twenty-five men for two weeks per year while a sawmill i s rendered inoperable by high water. The Water Investigations Branch of the B r i t i s h Columbia Department of Lands, Forests and Water Resources has studied the problem, recommended channel improvements and proceeded with the necessary construction. The estimated cost of the project was $46,000,00 and the design peak daily discharge was 650 c f s . corres- ponding to a flood with a return period of 50 years (2). For the present, i t appears that Lumby i s out of danger from floods from the two creeks. However, in the face of increasing population and lack of zoning, there i s l i t t l e doubt that problems w i l l arise in the future. Therefore, the problem of flooding i n Lumby should be included in any comprehensive plan for increased control of water from Duteau Watershed. 50 CHAPTER VI PLANS FOR THE FUTURE At the present time, there i s some minor c o n f l i c t over the use of water from Duteau Creek and i t i s probable that this c o n f l i c t w i l l increase i n the coming years unless remedial measures are undertaken. Two obvious types of solution to this water resource problem are construction of additional storage and better management of the existing system. CONSTRUCTION OF ADDITIONAL STORAGE This has been the traditional solution to water shortage problems, perhaps because the engineering profession has h i s t o r i c a l l y been commissioned to solve problems by construction of new f a c i l i t i e s . Studies have already been made of constructional measures to increase water a v a i l a b i l i t y i n Vernon Irrigation D i s t r i c t . Present dams could be enlarged and new dams could be b u i l t to hold more of the spring freshet waters from snowmelt. The Haddo Lake watershed also has a unique feature which could be u t i l i z e d to produce another water saving project. Haddo Lake watershed i s divided into two di s t i n c t partsj that which drains f i r s t into Aberdeen Lake, and that part of the water- shed which drains directly into Haddo Lake without f i r s t passing through Aberdeen Lake (Figure i l ) . These two areas are each approximately twenty square miles and would be expected to produce approximately the same amount of run-off 0 Aberdeen i s usually capable of containing 51 a l l the run-off from i t s watershed and in fact rarely f i l l s . Haddo Lake however, has only about one quarter the storage volume and as a result the lake f i l l s and then much of the freshet water i s s p i l l e d and, from the point of view of irr i g a t i o n , i s wasted. The topography of the watershed lends i t s e l f to the construction of a canal which would take water from the Grizzly Swamp area, which would ordinarily drain dir e c t l y into Haddo Lake, and convey this water to Aberdeen Lake thus u t i l i z i n g more of the storage volume available at Aberdeen Lake. Increasing the height of the Haddo Lake dam i s less feasible as this would involve a number of saddle dams around the perimeter of the storage area, MANAGEMENT The second method of solving the water conservation problem involves better management. Many suggestions have been made but a l l involve some special problems and before these suggestions can be Implemented, the problems must be resolved. These problems are examined i n the following section. Economic Incentive Economists show that the consumption of a commodity decreases as i t s cost increases. This could be applied to irr i g a t i o n water i n the Vernon Irrigation D i s t r i c t by the implimentation of a unit cost for water. In 1971, the tax for ir r i g a t i o n water service i n V.I.D. was $27.00 per acre. This i s rather insignificant when compared to the annual prunning, spraying, picking and other costs which are estimated 52 at $300.00 per acre. However, $27.00 i s significantly greater than the $2,00 to $5.00 per acre per year charged to irrigators i n other parts of Canada and an increase i n the cost of water might raise the farmers' annual costs above annual revenue thereby squeezing out those presently operating on a small p r o f i t margin. Unemployment i s already a problem and the cost of supporting unemployed farmers could be much greater than possible gains from higher charges. Also, i t was estimated i n the 1965 report that the cost of water-meters for a l l users would be $150,000.00. Changing to a different form of charging for water use could create severe social problems and would require a major change in government policy. I t seems that such a change could not be quickly brought about. Extra Equipment Under some circumstances, i f an irriga t o r purchases extra equipment he can conserve water. Extra equipment allows the irrigator to cover his f i e l d i n a shorter time interval and this means he can shut down his lines while the weather i s cool or wet, but, i f there i s a sudden change to hot dry weather, he can s t i l l irrigate the whole farm before the s o i l drys out too much. In Vernon Irrigation D i s t r i c t , however, the maximum delivery rate to a farm i s set at 5 U.S. gallons per minute per acre. Extra equipment would be of l i t t l e advantage since lower application rates would have to be used in conjunction with extra equipment thus lengthening the time for each application. 53 Better Operation of Reservoirs At present the Vernon Irrigation D i s t r i c t operates two snow courses in the Haddo Lake watershed. These yie l d results which t e l l whether this run-off w i l l be greater or less than usual but do not give precise estimates of the expected run-off. Therefore, the reservoirs are operated with l i t t l e knowledge of the inflow which w i l l occur. If better hydrologic data were available to the manager of the d i s t r i c t , the lakes could be operated to obtain maximum use of available water for a l l resource users. However, techniques w i l l have to be perfected and hydrologic stations installed i n the area before this type of management can become a r e a l i t y . Scheduling This method of determining the precise time i r r i g a t i o n i s required, holds promise of water conservation i n the Okanagan Valley. The biggest problem i s to get the irrigators to use i t . Teaching programs so far have proved unsuccessful i n inducing large numbers of irrigators to switch to scheduling. Perhaps few people see the need for water conservation. However, i t i s not hard to visualise the valley divided into zones by evapotranspiration rates, and daily water use figures for farmers use published i n newspapers, included with farm news and available by telephone. At present, no commercial production of the Ogopogo evaporimeter i s underway and the only models available have been those produced by Summerland Research Station. Also, extension personnel i n the valley are probably already too overworked to introduce and back up a significant scheduling education program. Drip Irrigation Research i s currently underway at the Summerland Station on a new type of ir r i g a t i o n system. The system u t i l i z e s small diameter (l/l6" to l/32") tubes called "drippers", as a method of delivering the water to the trees. The ir r i g a t i o n water i s delivered to the f i e l d i n the conventional manner but perhaps at a lower pressure. Plastic tubing of two to three inch diameter i s then used to deliver the water near the trees—probably between every second row of trees. The water then enters a dripper which takes i t to a header. Prom the header, drippers lead to between five and ten points around the tree to deliver the water to the s o i l where i t w i l l be quickly picked up by the roots. With drip i r r i g a t i o n , the whole f i e l d i s irrigated at the same time. SUMMARY The problems and conflicts of the water resource users of Duteau Greek watershed seem l i k e l y to increase i n the future. Alternative solutions of these problems at the system level include construction of more reservoirs, construction of a diversion canal, and improved management of the existing system i n a number of ways. There may be room for better reservoir operation but the need for better hydrologic data w i l l have to be sati s f i e d f i r s t , and the implementation w i l l involve learning more about the hydrology of the area and about the system as a whole. There i s also some oportunity for conserving water through scheduling which involves learning at the farmer l e v e l . It seems that management of the system should be looked on partly as a 55 learning process which w i l l allow both the system managers and the farmers to anticipate their problems, understand the opportunities and alternatives, and deal with problems i n good time. 56 CHAPTER VII CONCLUSIONS This study has examined the Vernon Irrigation D i s t r i c t , the largest i r r i g a t i o n d i s t r i c t i n the Okanagan Valley, and one which has recently been modernized. The old system has served the residents well and i t i s to be hoped that the new one w i l l serve equally well. Reasons for the selection of the new system, design c r i t e r i a , and details of the operation of the system have been given i n the hope that they may prove valuable to designers of future systems, farmers and ir r i g a t i o n managers. As water demands continue to grow, management problems w i l l become more complex and w i l l require more accurate information about the a v a i l a b i l i t y and use of water for their solution. New multi-use management policies w i l l have to be formulated to include non-irrigation demands. Eventually, i t may be necessary to construct additional storage f a c i l i t i e s and also perhaps to induce the farmers to conserve water. Water can be conserved by scheduling, and the problems and potential of this process have been examined i n some d e t a i l . Before i t can be widely adopted, however, there w i l l have to be an extensive learning program, not only on the part of the irriga t o r s , but also on the part of the planners and system managers. Also new techniques such as drip i r r i g a t i o n which w i l l make water conservation easier may be developed, provided there i s continued research in i r r i g a t i o n . 57 B I B L I O G R A P H Y 1. B r i t i s h Columbia. Department of Agriculture. British Columbia Irrigation Guide. Victoria, B.C. 2. . Department of Lands, Forests and Water Resources. Water Resources Service. Preliminary Report. Corporation of the Village of Lumby Flood Protection. Victoria, 1969. 3. . Water Act and Regulations. 1968. 4. Canada. Department of Agriculture. Farming in the Vernon Irrigation District. Unpublished Report. Ottawa, Canada. 1963. 5. Fuller, J. D. C. Vernon Irrigation District Engineering Study. Department of Lands, Forests and Water Resources. Victoria, 1965. 6. Gabriel, Theresa. A Brief History of Vemon3 B.C. Vernon Centennial Committee, Vernon, B.C. 1958. 7« Linsley, R. K., M. A. Kohler and J. L. H. Paulhus. Hydrology for Engineers. Toronto: McGraw H i l l Co. Inc., 1958. 8. MacKenzie, A. R. Report of the Coldstream Estate. Consulting Engineer's Report. Vancouver, 1913. 9. O'Riordan, J. "Efficiency of Irrigation Water Use." Unpublished Doctor's Dissertation, University of B.C., 1969. 10. Pennington, D. J. North Okanagan Irrigation and Domestic Water Supplies. Vol. I, Irrigation Water Supplies. B.C. Department of Lands, Forests and Water Resources, Victoria, 1961. 11. . North Okanagan Irrigation and Domestic Water Supplies. Vol. II, Domestic Water Supplies. B.C. Department of Lands, Forests and Water Resources, Victoria, 1961. 53 13. Russell, S. 0., M. C. Quick and W. D. Finn. Water Resources of the Nicola-Kamloops Area: Preliminary Appraisal. Report No. 1, University of Br i t i s h Columbia, Vancouver, 1969. 14. Schwab, 0. S. and others. Soil and Water Conservation Engineering. New York: Wiley, 1966. 15. Spence, C. C. An Appraisal of the Economic Benefits of the Vernon Irrigation District. Canada. Department of Agriculture, Ottawa, 1964. 16. Vernon Irrigation District Annual Report. Vernon, B.C., 1920 to 1970. 17. Wilcox, J. C. "A Simple Evaporimeter for use i n Cold Areas," Water Resources Research^ Vol. 3, No. 2 ( 1 9 6 7 ) . 18. , and C. H. Brownlee. Scheduling of Irrigations in Orchards. Summerland Irrigation Technical Bulletin No. 5, Summerland, 1969. 19. . Some Estimates of Irrigation Requirements in 1967. Canada Land Inventory Evaporation Stations, Summerland, 1969. 20. . "Credit to Give for Rain When Scheduling Irrigation in Semi-Humid Areas," Canadian Agricultural Engineering^ Vol. 12, No. 2, pp. 33-38. 21. and H. C. Korven. "Effects of Weather Fluctuations on the Scheduling of Irrigation," Canadian Journal of Plant Science3 Vol. 44 ( 1 9 6 4 ) . 22. Willcocks, T. J. "Irrigation Requirements for A l f a l f a i n the Nicola Valley," Unpublished Master's Dissertation, University of B.C., 1970. 23. 24. Zimmerman, J. D. Irrigation. New York: John Wiley & Sons, 1966. Personal interview with T. J. Willcocks, Canada Department of Fisheries. 59 GLOSSARY Application Efficiency - The ratio of net volume of desired application to the gross volume of water delivered by the sprinklers to effect the desired application. Application Rate - The rate at which irr i g a t i o n water i s applied to the s o i l . Units: inches per hour. Effective Rooting Depth - That depth i n the s o i l above which the roots obtain 90% or more of their water between irrigations. Evapotranspiration - Mater transpired by plants, b u i l t into plant tissue, and evaporated from the s o i l surface. Also called "Consumptive Use", Evapotranspiration Rate - Rate of evapotranspiration expressed i n inches per day, per ir r i g a t i o n interval, per month or per growing season. Field Capacity - Soil water content retained by the s o i l following an irr i g a t i o n or heavy rain, after downward movement of water has materially decreased. I t i s the upper l i m i t of s o i l water available for plant use. Units: percentage of dry weight of s o i l , inches of water per foot of s o i l or per pr o f i l e . I n f i l t r a t i o n - The downward movement of free water into the s o i l through the s o i l surface. I n f i l t r a t i o n Rate - The rate of downward movement of free water into the s o i l through the s o i l surface. Units: inches per hour. Irrigation Cycle - The number of days to irrigate a given area not counting the time l o s t during or between irrigations. I r r i g a t i o n I n t e r v a l - The number of days between the s t a r t of an i r r i g a t i o n a t any one spot and the s t a r t of the next i r r i g a t i o n a t the same spot. Leaching - The process of removing s o l u b l e m a t e r i a l from the s o i l by passage of water through the s o i l . Maximum Allo w a b l e S o i l Water D e f i c i t - The range of water content between f i e l d c a p a c i t y and t h a t water content below which growth and y i e l d are a f f e c t e d a d v e r s e l y . Peak E v a p o t r a n s p i r a t i o n - The average d a i l y e v a p o t r a n s p i r a t i o n d u r i n g the p e r i o d of maximum e v a p o t r a n s p i r a t i o n , f o r a p e r i o d of any s t a t e d l e n g t h . U n i t s : inches per day. Permanent W i l t i n g P o i n t - The water content of the s o i l when p l a n t s growing i n i t are w i l t e d t o the p o i n t where they w i l l not recov e r when placed i n the dark f o r 12 hours i n an atmosphere of 100% r e l a t i v e humidity. I t occurs a t about 15 atmospheres or 15 bars o f s o i l moisture t e n s i o n . U n i t s : percentage o f d r y weight o f s o i l . A l s o c a l l e d "Permanent W i l t i n g Percentage", Safe I n t e r v a l - The maximum i n t e r v a l i n days t h a t can be allow e d between i r r i g a t i o n s i n the heat o f the summer without danger of i m p a i r i n g p l a n t growth or y i e l d . Scheduling o f I r r i g a t i o n - A procedure whereby water i s a p p l i e d i n such a manner t h a t the s o i l water content i s maintained w i t h i n the optimum range, without unnecessary wastage of water. Seasonal E v a p o t r a n s p i r a t i o n - The t o t a l e v a p o t r a n s p i r a t i o n d u r i n g the growing season o f the crop. U n i t s : inches of water . S o i l Water D e f i c i t - F i e l d c a p a c i t y minus a c t u a l s o i l water content. U n i t s ; inches per f o o t of s o i l or per p r o f i l e . T r a n s p i r a t i o n - Evaporation of water from the sur f a c e of the p l a n t , and in particular from the leaves. It does not include evaporation of water adhering to the outside of leaves because of r a i n f a l l , i r r i g a t i o n or dew.

Cite

Citation Scheme:

    

Usage Statistics

Country Views Downloads
Canada 5 0
United States 5 0
France 1 0
United Kingdom 1 0
City Views Downloads
Unknown 5 28
Mercer Island 3 0
Nanaimo 2 0
York 1 0
Ashburn 1 0

{[{ mDataHeader[type] }]} {[{ month[type] }]} {[{ tData[type] }]}

Share

Share to:

Comment

Related Items