A MODEL FOR THE DETERMINATION OF THE NATURAL STREAMFLOW OF VENISON CREEK
R.W. Irwin W.T. Dickinson W. Lammers Member CSAE School of Engineering Hydrologist School of Engineering University of Guelph Water Resources Division University of Guelph Guelph, Ontario Ministry of the Environment Guelph, Ontario Toronto, Ontario
INTRODUCTION model, the basin characteristics being model that the effects of groundwater suitable for the study, and hydrometric takings on streamflow, observed at an Water takings for the irrigation of and observation well data being available inventory point at a downstream gauge, tobacco in Ontario reduce streamflow (3). will lag the actual takings by several days. during the months of July and August in Initially, there will be local adjustments most years. Yakutchik and Lammers (5) in the water table. Additional takings at estimated streamflow reduction for Big MODEL DEVELOPMENT the same or nearby sites will result in Creek at Delhi in the order of 70% for the additional water-table adjustments. The period July 30 to August 1, 1964, due to For this study, the natural discharge of effects of these takings are cumulative, irrigation takings in that basin. These a stream is defined as the discharge because each additional groundwater reductions affect the natural functions of generated in the basin under existing land taking will add to the existing effects of streams, and cause water use conflicts use. A large number of man-made ponds previous takings. Therefore, the effects of between stream users. are part of the existing land-use pattern groundwater takings on streamflow will of Venison Creek and have increased the be of little significance during the start of For the management of water total free water surface of the basin. the irrigation period but will increase resources in such basins, knowledge is Their effects are incorporated in the steadily as the irrigation period progresses required regarding (i) the amount of natural discharge as defined. until groundwater takings cease. water available during peak water demand periods; (ii) the amount of water likely to The model is based on three assump A basic relationship for natural stream- be used from various sources; and (hi) the tions regarding the effects of various flow determination may be expressed: relative effects of water takings from types of water takings on streamflow different sources on streamflow. Informa reduction: (1) tion regarding the natural flows available (i) Takings from streamflow have a for use is often scarce, since streamflow direct effect on streamflow reduc where records for many of the streams in tion, Southern Ontario began after the practice (ii) Takings from surface-water storage Q = natural streamflow; of tobacco irrigation was established in areas not located on the stream (i.e. M = measured streamflow; D = direct streamflow losses due to stream- the early 1950's. Therefore, there is a farm ponds) do not affect stream- flow takings; and need for a method to estimate natural flow, / = indirect streamflow losses due to ground streamflow patterns in order to evaluate (hi) Takings from groundwater resources water takings. the effect of water takings. Such have an indirect effect on streamflow information is important to the develop reduction. For a consideration of mean daily ment of improved water management streamflow values, the D and / terms may systems in the region. Assumption (i) is readily apparent. be expressed as: Assumption (ii) is valid for the case A streamflow determination model has involving intermittent streams, but is not (2) been developed for the generation of strictly true for permanent streams. ^L-(r-i)5' estimates of natural mean daily stream- Assumption (hi) considers that ground flow. Input for the model includes water takings, whether from wells or and records of existing daily streamflow, and ponds dug to below the water table, n - b water takings from ground and surface reduce the rate of groundwater discharge U =AR2 Gtfoin
12 CANADIAN AGRICULTURAL ENGINEERING, VOL. 17 NO. 1, JUNE 1975 direct streamflow takings, on the «th TABLE I STATISTICS ON IRRIGATORS AND WATER-TAKING RECORDS day following the commencement of irri gation in the basin for a selected year understudy; Year: 1967 1968 1969 P = scale factor to convert reported daily streamflow takings to total daily stream- Total irrigators 102 102 105 flow takings; Irrigators holding permits * 99 99 102 T = travel time, in days, of streamflow from Permitted water sources* 108 108 113 farthest water-taking site on the stream Irrigators submitting suitable to the inventory station at downstream records (%) 65 61 54 gauge; n = day number following the commence * Certain irrigators are exempted. ment of irrigation in basin; * Certain irrigators use more than one water source. t = time, in days; S( = reported daily streamflow taking on day t\ crops was estimated from water-taking records satisfactory for analysis. Statistics Itn ~ mean daily streamflow loss on the «th records3 on file with the Ministry of the on irrigators and water-taking records are day due to takings from groundwater; Environment for the 1967, 1968 and shown in Table 1. A- constant, characteristic of the study basin; 1969 irrigation seasons. This estimation R = scale factor to convert reported ground was carried out by: Figure 2 reveals a histogram of the water takings to estimated total ground 1. Compilation of a list of permits issued number of irrigators reporting water water takings; by the Ministry to tobacco growers in takings and the histogram of the total b = average delay time, in days, before the the study basin. reported daily takings. These histograms effects of groundwater takings on previ 2. Compilation, assessment, and classifi portray three patterns of water use. The ous days are felt in streamflow reduction cation of water-taking records submit histogram for 1968 shows a period of at the inventory station; ted to the Ministry by the permittees intensive water use as compared to 1967 Gf = reported groundwater taking on day t; C = constant, characteristic of the study for the three irrigation seasons. and 1969. basin; 3. Determination of daily totals of m = day number, counted from first day of reported water takings from each of Water is withdrawn from three main irrigation, for last day of water takings the categories and sources of supply. sources in the basin: groundwater, from groundwater. streamflow, and surface-water storage. Classification of these records was Figure 3 shows histograms of water use Equations (2), (3) and (4) were substi based on the following types of with by source for 1968. tuted into equation (1) to form: drawal sites utilized: 1. Withdrawal from groundwater re n-S The following assumptions were used Qtn =Mtn +^ [Stn - 1+Stn] +AR X Gt sources through water takings from to estimate total daily and seasonal L f = 1 wells and sandpoints and from dugout irrigation water use in the study area: ponds not connected to a stream or (i) All irrigators possessing permits to for located in a streambed of an intermit take water would have submitted tent stream. «
CANADIAN AGRICULTURAL ENGINEERING, VOL. 17 NO. 1, JUNE 1975 13 />;Xyv>\
-N-
* . Wtll or «onde«iM • Dugout, not connected to ttroom Y-~*r- Ougout, connected to streom ,X~ < Dugout, on-itreom pond &&%&o> J>. Withdrowgl from «r«t«rcourM ^a Storage and witndrowol
A Mf-tl— Streomflow gouging ttotion 0 3 A ObMaatlen wen
VENISON CREEK DRAINAGE BASIN
SCALE IN MILES
Figure 1. Venison Creek drainage basin.
14 CANADIAN AGRICULTURAL ENGINEERING, VOL. 17 NO. 1, JUNE 1975 relationship, but were not consistent among the 3 yr. The exception in 1968 was caused by an unusually heavy storm which resulted in a substantial rise in the water table.
Seasonal curves of groundwater stage and stream discharge under baseflow conditions were used as rating curves to estimate the natural baseflow during and shortly after the irrigation period using groundwater stage as control. A trace of the estimated natural groundwater dis charges is showri in Figure 5 for the 1968 irrigation period.
10 20 10 20 31 10 MODEL FITTING AUGUST JULY AUGUST Four basin constants, A, b, C, and T9 Figure 2. Number of irrigators reporting taking water and their total daily takings. 1967-1969. were determined for the Venison Creek basin. The travel time, T, of equation (2) was estimated to be 2 days. The time of concentration under storm runoff condi tions was calculated to be about 9 h. Under baseflow conditions, the travel time would be considerably larger due to energy losses in the stream channels. It r r was assumed, therefore, that the effects of water withdrawal from the headwaters of Venison Creek would be observed the r next day in a reduction of natural r •^ - z streamflow at the inventory station. 5 5
s The terms A and b of equation (3) z U were empirically determined from rating z ° TfMTfi^ Jl Al "L flh curves of groundwater stage versus GROUNO-VVATER TAKIN GS SURFACE-VVATER TAKING S < groundwater discharge using stage data as
tr control. From trial runs on 3 yr of •" 15 irrigation and baseflow data, the values 1 A = 0.03 and b = 5 days were selected. LU (J < cc The C term of equation (4) was > 10 < calculated from 3 yr of water-use data by - solving the common ratio of the geo " -n metric series whose first term was equated to the unaccountable streamflow reduction effects of groundwater takings. The C values were 0.93, 0.94, and 0.95 Jfid 'li _nrlll£. lb for the 3 yr of record. A mean of 0.94 was selected for use in equation (4). ST 1EAMFLOW TAKINGS ON-STREAM-STORAGE TA KING S Equations (5) and (6) were used to estimate daily values of natural stream- 5 10 15 20 25 31 5 10 5 10 15 20 25 31 5 10 flow during and after each annual AUGUST JULY AUGUST irrigation period during 1967-1969. Figure 3. Reported daily water takings from indicated sources in 1968. The hydrographs of recorded stream- flow, estimated natural streamflow, and well was selected because the water table commenced to provide flow data for a natural baseflow for the 1968 irrigation at this site would not have been affected certain water stage range. However, these season are shown in Figure 5. The by water takings from the nearest data were for the early part of the closeness of fit between the model output groundwater-taking sites. Relationships irrigation period and were adjusted values of natural streamflow and the were established for June to September upwards for amounts of estimated daily independently derived estimates of natur periods, 1967 to 1969. water takings from streamflow. al streamflow under baseflow conditions is good, despite the fact that satisfactory The relationships for 1968 are shown The annual relationships were consis water use information was available for in Figure 4. It was often necessary to use tent within each June to September only about 61% of the known 1968 streamflow data after irrigation had period, with the exception of the 1968 irrigators.
CANADIAN AGRICULTURAL ENGINEERING, VOL. 17 NO. 1, JUNE 1975 15 o < CONCLUSIONS
The natural streamflow determination Q Z 125 model satisfactorily estimated the natural streamflow of Venison Creek O co during periods of intensive irrigation 150 water use. The closeness of fit between the model output values and independently derived estimates of natural streamflow under baseflow con < S ditions is good. Testing of the model te s suggested that reliable estimates of AUG
< natural streamflow could be generated 225 with water-use information from about Q Z 54 to 65% of the known irrigators. D O 0.9 The streamflow reduction due to GROUND-WATER DISCHARGE IN M3/SEC groundwater takings in Venison Creek (HYDROMETRIC STATION 02GC021) basin was found to be significant, Figure 4. Groundwater stage and groundwater discharge relationships, Venison Creek drainage particularly during the latter part of the basin, June - September, 1968. irrigation period. In 1968, about 56% of the estimated groundwater takings were accounted for in streamflow reduction estimates at the end of the irrigation period. These effects should be con sidered in the development of a water management scheme in the Venison Creek basin.
SUMMARY
Water takings for irrigation reduce streamflow during the months of July and August in most years. A determina tion model was developed for Venison Creek basin based upon inputs of streamflow, groundwater levels and water takings from several types of source by irrigators.
The model satisfactorily determines realistic estimates of natural streamflow - RECORDED DISCHARGE ESTIMATED NATURAL GROUND-WATER and the effects on streamflow due to DISCHARGE BASED ON OBSERVATION WELL 3A DATA - ESTIMATED NATURAL DISCHARGE AS PER MODEL water takings for irrigation. ESTIMATED NATURAL DISCHARGE AS PER MODEL. -_-. ESTIMATED EFFECTS OF • MINUS THE EFFECTS OF GROUND-WATER TAKINGS STREAMFLOW TAKINGS ON STREAMFLOW DEPLETION _l_ I
OBSERVATION WELL 3A ACKNOWLEDGMENTS
Water-taking and observation well data made available by the Ontario Water Resources Commission and its financial assistance is gratefully acknow ledged.
250 I I I I I I I I I I I I I I III I I I I I i I I I I I I I I I I I I I I I I I I 1 I I II I I I \ I 1 I I I I I I I I I I I 5 10 15 20 25 31 5 10 15 20 25 3 REFERENCES JULY AUGUST 1. Canada Department of Energy, Mines and Figure 5. Estimated basin precipitation, and hydrographs of streamflow and water-table Resources. 1967. Water Survey of fluctuations, Venison Creek drainagebasin, July and August, 1968. Canada, Surface Water Data, Ontario.
16 CANADIAN AGRICULTURAL ENGINEERING, VOL. 17 NO. 1, JUNE 1975 TABLE II NUMBER OF IRRIGATORS REPORTING TAKING WATER, HAVING PERMITS AND NOT REQUIRING PERMITS, AND SCALE FACTORS TO CONVERT REPORTED TO ESTIMATED TOTAL TAKINGS BY SOURCE, 1967-1969
No. of irrigators Scale facteirs ]Reporting Having to convert Reporting taking water by permits to take Exempted from reported to estimated Source taking water source water from source requiring permits total takings*
(1) (2) (3) (4) (5) '67 '68 '69 '67 '68 '69 '67 '68 '69 '67 '68 '69 •67 '68 '69
Groundwater 29 29 15 18 22 11 47 47 51 3 3 3 1.7 1.4 1.5 Surface water 37 41 13 25 34 12 58 58 59 0 0 0 1.5 1.2 1.1 Streams and dugout ponds connected to streams (streamflow) 29 32 10 21 27 9 44 44 45 0 0 0 1.4 1.2 1.1 Storage in permanent and intermittent streams 8 9 3 4 7 3 14 14 14 0 0 0 2.0 1.3 1.0
t The difference between the values in columns (1) and (2) is equal to the number of irrigators reporting taking water, but whose records were unsuitable for analysis. * The scale factors were derived using the following equation; the terms in the equation refer to the values in the numbered columns:
Col.(l) (Col. (3) + Col. (4)) Scale factor = X Col. (2) Col. (3)
Canada Department of Energy, Mines and determination of the natural streamflow Toronto, Ontario. Queen's Printer, 1970. Resources. 1968, 1969. Water Survey of of Venison Creek. M.Sc. Thesis, Univer Canada, Provisional Streamflow Records, sity of Guelph, Guelph, Ontario. Yakutchik, T.J. and W. Lammers, 1970. Ontario. Water resources of the Big Creek drainage The Ontario Water Resources Com basin (Water Resources Report No. 2), Lammers, W. 1970. Model for the mission Act, R.S.O. 1960 Chapter 281, OWRC, Toronto, Ontario.
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