Comparison of Evaporation Computation Methods, Pretty Lake, Lagrange County, Northeastern Indiana GEOLOGICAL SURVEY PROFESSIONAL PAPER 686-A Comparison of Evaporation Computation Methods, Pretty Lake, Lagrange County, Northeastern Indiana By JOHN F. FICKE HYDROLOGIC AND BIOLOGICAL STUDIES OF PRETTY LAKE, INDIANA GEOLOGICAL SURVEY PROFESSIONAL PAPER 686-A Studies using Jive common computation methods found the mass-transfer method best suited for year-round measurement of evaporation rates UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1972 UNITED STATES DEPARTMENT OF THE INTERIOR ROGERS C. B. MORTON, Secretary GEOLOGICAL SURVEY V. E. McKelvey, Director Library of Congress catalog-card No: 78-179296 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price 70 cents (paper cover) Stock Number 2401-1144 CONTENTS Page Page Symbols. __________________________________________ V Water-budget studies______________________________ A23 Abstract_ ________________________________________ Al Instrument records_______________-__---_--_--_ 23 Introduction. ______________________________________ 1 Balancing the water budget (seepage correction) _ _ _ _ 24 Acknowledgments___ __________________________ 2 Evaporation from the water budget.___-______--__ 28 Description of Pretty Lake_________________________ 2 Evaporation-pan studies.__________-______----------_ 29 Temperature patterns.__________________________ 5 Kendallville station data____________ ___________ 29 Instrumentation and its operation ____________________ 5 Computed pan and lake evaporation-_____________ 32 Instrumentation for water budget_______________ 5 Advection and energy-storage effects._____________ 32 Instrumentation for energy budget._______________ 7 Wintertime evaporation and energy budget _______ 33 Thermal surveys__________________________ 9 Observed winter conditions_____________________ 34 Instrumentation for measuring mass-transfer para­ Application of open-water evaporation methods to meters-,..............,,. ____________________ 9 winter conditions___ ____________________ 35 Evaporation pans_____________________________ 9 Energy-budget studies__.__________________________ 9 Limited pan season__ _ ______________----_---- 35 Instrument records.___________________________ 10 Water-budget application_________._--_----__ 35 Changes in energy storage.______________________ 14 Mass-transfer method_____________-___-_-- 36 Interrelation of Q e, Qh, and Q w and the Bowen ratio. _ 14 Winter energy budget_____ _ ____________----_---_- 36 Results of energy-budget studies________________ 15 Comparison of results__ _ ________________--_-------_ 38 Sediment heating effects.____________________ 15 Results summarized.__________________-_--_----- 38 Mass-transfer studies______________________________ 18 Characteristics of results from individual methods. _ 38 Instrument records____________________________ 19 Conclusions._ _________________-_---------_--------- 46 Mass-transfer coefficient from energy-budget calibration. __________________________________ 19 References.___________________-_------------------- 47 Computation of evaporation by mass transfer. _____ 22 Index---____-----_--------_-- ------------------ 49 ILLUSTRATIONS Page FIGURE 1. Map of Pretty Lake study site. _ _____________________-__-----_----------------------------------- A3 2. Map of bottom configuration of Pretty Lake_____________________----_-------_--------------------- 3. Graph of temperature patterns.___________________-____-______----------------------------------- 4-9. Photographs: 4. Stream-gaging station on Pretty Lake inlet-_________-_----_--------------------------------- 5 5. Lake-stage control weir and recording gage on outlet channel-________-____-------------------- 6 6. Nonrecording rain gage at edge of Pretty Lake__________________----_----------------------- 6 7. Lake-stage gage located at public access area____________-_---------------------------------- 7 8. Temperature- and radiation-measuring equipment--______-_____------------------------------ 7 9. Instrument raft,____________________________--_____-_------_----------------------------- 9 10. Time graphs of solar radiation (Q.)_______________________-___------------------------------------ 10 11. Graphs showing relation of long-wave radiation (Q~) as measured by flat-plate radiometers and as computed by the Koberg method._____________________________________-------------------------------- 11 12-14. Time graphs: 12. Long-wave radiation (Qa)_____._________________________---_------------------------------ 12 13. Air and water-surface temperature records. _ _____________-_--_----------------------------- 14. Vapor-pressure records.______________________-______----__------------------------------- in IV CONTENTS Page FIGURE 15. Graphs showing yearly temperature and heat-storage pattern of Pretty Lake sediment-__. ____--._______ A17 16. Graph showing estimated annual cycle of average heat storage in sediment_________________________ 18 17. Time graphs of wind speeds__________________________________________________________________ 20 18. Graph showing relation of mass-transfer product to evaporation measured by the energy-budget method 21 19. Graph of mass-transfer coefficients determined by different methods _______-____--_-_-____!.--__-__-. 22 20. Pretty Lake inlet hydrographs.___________________-____-____-___----_--___--_----__---_----_.. 24 21. Pretty Lake outflow hydrographs._______._________________-___-__---_-__--_--- 25 22. Pretty Lake stage hydrographs....__._.___..._______________________-_____---_ 26 23. Graphs of daily precipitation measured at Pretty Lake___________________________ 26 24-26. Graphs showing: 24. Relation of corrected stage change to the mass-transfer product.---________ 27 25. Relation of corrected stage change to the mass-transfer product by subperiods _ 29 26. Seepage during 1964 and 1965 open-water periods. ___-___-_______-._____-- 30 27. Graph showing diurnal fluctuation of air and ice-surface temperatures.- - _____________ 36 28. Time graphs of wintertime vapor pressure _________-______-_---_-----_---_------- 37 29. Graphs showing wintertime relation of the mass-transfer product and the water budget. 38 30. Hydrographs of evaporation rates computed by different methods. __________________ 42 31. Bar-graph comparison of summarized evaporation results __________________________ 44 TABLES Page TABLE 1. Periods of use for flat-plate radiometers at Pretty Lake---------------------------------------------- A10 2. Summary of data from flat-plate radiometers.________________-_____--_--___------------------------ 11 3. Summary of energy-budget terms and evaporation computation for open-water periods, l963-65-_____.-_- 16 4. Estimated energy conducted as sensible heat (Q A), according to equation 7 and assuming JV=0.0060_ _____ 17 5. Summary of mass-transfer terms for open-water periods, 1963-65_______-___-_____---_--_------------- 22 6. Summary of water-budget terms for Pretty Lake open-water periods, 1963-65______________-_---_-__--- 28 7. Corrections for seepage applied to. water budget, and water-budget evaporation.---_________-_-_-___---- 29 8. Daily evaporation from U.S. Weather Bureau class-A pan at Kendallville, IncL____---_---------------- 31 9. Daily evaporation from U.S. Weather Bureau class-A pan at Culver Experiment Farm, Ind_____-__-___-- 31 10. Lake evaporation based upon data from Kendallville or Culver pan and average annual coefficient of 0.76, computed by Pretty Lake energy-budget periods__________________---_-------------------------- 32 11. Computed pan and lake evaporation by use of U.S. Weather Bureau method with Pretty Lake station data__ 33 12. Advection and storage corrections for pan-based evaporation data__________________---.-------------- 34 13. Computed wintertime pan and lake evaporation for open-water periods that were not included in table 11- 35 .TABLE 14. Wintertime water-budget terms_________________________-_________-------_------------------------ 35 15. Summary of wintertime mass-transfer terms for Pretty Lake, with evaporation computed by equation 14_. 36 16. Estimated terms for wintertime energy budget. ____________________--__-__-_----------------------- 39 17. Summary of data requirements for different evaporation computation methods____________-_----------- 39 18. Pretty Lake evaporation as computed by different methods for open-water periods, 1963-65 ___-_-_-_:- 39 19. Pretty Lake evaporation as computed by different methods for wintertime periods, 1963-65 ___________ 41 20. Summary of Pretty Lake evaporation, as computed by different methods, for similar periods during 1963-65_ _ 41 21. Annual and May-October evaporation from Pretty Lake--------------------------------------------- 46 SYMBOLS A Surface area. Incoming solar radiation. c Specific heat of water. Net energy advected into the lake. E Evaporation. Energy advected by evaporating water. EEB Evaporation computed by the energy-budget method. Increase in stored energy. EMT Evaporation computed by the mass-transfer method. Bowen ratio. EWB Evaporation computed by the water-budget method. Thermal conductivity of the sediment. ea Vapor pressure of the air. Dry-bulb air temperature. e,Q Saturation vapor pressure at the temperature of the water Arbitrary base temperature (0°C) used in energy surface. computations. G Net underground seepage. Temperature of evaporated water. I Surface inflow. Amplitude of temperature stress on sediments. Iv Precipitation falling