EVAPOTRANSPIRATION CALCULATION AND DETERMINATION OF EVAPORATION EFFECT IN THE SOIL USING STABLE ISOTOPES (18O AND 2H) AND HYDROMETRIC MEASUREMENTS

Samuel Jonson Sutanto

Abstract


Perhitungan evapotranspirasi sangat dibutuhkan dalam perencanaan hidrologi, agronomi, kehutanan,
sumber daya air, irigasi, pemodelan ekosistem, dan lain sebagainya. Evapotranspirasi dapat dihitung dengan
berbagai macam metode, namun perhitungan langsung dari aktual evapotranspirasi sangat jarang ditemui
dan mahal. Neraca air dan pemodelan numerik HYDRUS1D
digunakan untuk menghitung aktual
evapotranspirasi dengan metode PenmanMonteith
sebagai pembanding. Perhitungan dilakukan pada
sebuah lisimeter dengan rumput sebagai tanaman. Hasil dari perhitungan menunjukkan bahwa PenmanMonteith
dan model HYDRUS1D
mempunyai pola yang sama, sementara hasil dari perhitungan neraca air
sangat dipengaruhi oleh perubahan tampungan air di dalam tanah. Evapotranspirasi ratarata
dari neraca
air, PenmanMonteith
dan HYDRUS1D
secara berurutan adalah 3,4 mm/hari, 3,6 mm/hari dan 4,2
mm/hari. Kedalaman dari efek evapotranspirasi adalah 20 cm yang dapat dideteksi dengan menggunakan
pengukuran isotop 2H dan 18O.


Keywords


Evapotranspirasi, neraca air, PenmanMonteith, HYDRUS1D, dan isotope

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DOI: https://doi.org/10.32679/jth.v2i2.252

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