The application and analysis of three evapotranspiration models in eastern North Carolina / by Stephen Powell Moore.

Author/creator Moore, Stephen Powell author.
Other author Steila, Donald, 1939- degree supervisor.
Other author East Carolina University. Department of Geography.
Format Theses and dissertations
Publication InfoGreenville, N.C. : East Carolina University, 1977.
Description105 leaves : illustrations ; 28 cm
Supplemental ContentAccess via ScholarShip
Subjects
Evapotranspiration.

Summary The Thornthwaite, Blaney-Criddle, and Holdridge methods of calculating evapotranspiration have been applied in a broad range of climatic regimes. Each model has proved in certain areas to yield more accurate results than the other two depending on the soils and climate. This research examines the applicability of the three methodologies for prediction of actual ̌vapotranspiration in eastern North Carolina. Soil moisture retention was calculated with the use of Bouyocos gypsum blocks on ten soil series under a uniform stand of field corn (Zea mays L.). Field observations were conducted twice weekly, while rainfall, temperature, humidity, and crop growth stages were continuously monitored. From the soil moisture retention values, AS was calculated which was then compared to each of the computed values of the three methodologies being examined. Correlation coefficients indicated substantial agreement between the predictive ability of the three methodologies but revealed a weak relationship between the actual data and the three methodologies. The predicted values had a tendancy to lag behind the actual moisture release values as evidenced by the moisture stress on the crop. On the average the methodologies deviated from the actual values by 20% but this does not emphasize these periods when actual soil moisture would be as little as 5 mm the rooting zone and the predicted values would indicate moisture in the rooting zone to be as high as 55 mm (a range of error of 110%). This large departure could severely endanger crops if irrigation periods v/ere based upon these theoretical predictions. The theoretical data was subsequently divided into four 25% categories from the highest to the lowest moisture holding values and a correction factor was derived for each category. This corrected data was then compared with the actual data and yielded significantly stronger correlations than the previous comparison. This corrective alteration of the theoretical methodologies could prove invaluable in the determination of irrigation practices and serve as a guideline for further experimentation on predictive moisture-exchange models in other climatic regimes.
General note"A thesis presented to the faculty of the Department of Geography ... in partial fulfillment of the requirements for the degree Master of Arts in Geography."
General noteAdvisor: Donald Steila
Dissertation noteM.A. East Carolina University 1977
Bibliography noteIncludes bibliographical references (leaves 102-105).

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