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| Titel |
Adjusting soil water balance calculations for light rainfall, dew, and fog. |
| VerfasserIn |
R. L. Snyder, D. Spano, R. Moratiel |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250058678
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| Zusammenfassung |
| The main sources of water for an irrigated crop include irrigation applications,
precipitation, water tables, fog interception, and dew formation. For a well-drained soil in a
climate where there are a few events of fog, dew, or light rainfall, computing a
water balance is relatively easy, but it is complicated in regions characterized by
considerable events of fog, dew and light rainfall. In these regions, growers are hesitant to
use ET-Based scheduling because the cumulative crop evapotranspiration is often
considerably higher than the soil water depletion. We will present a simple and practical
procedure to estimate the contribution of fog interception, dew, and light rainfall to daily
crop evapotranspiration in California and to show how to use the information to
improve water balance calculations for efficient water use in irrigation. It is assumed
that the relationship between normalized hourly ETo and time of the day is similar
to the relationship between normalized hourly ETc and time of the day. We can
describe the change in soil water depletion (ΔDSW) on that day as: ΔDsw =ETc x F
where F is the fraction of ETc coming from the soil, and F is determined using the
expression:
F = ––1–––
1+ e(t-11.265.5)
Where t is the approximate local standard time in hours when the crop dries. This
simple method improves water balance scheduling and the adoption of the ET-based
scheduling method in microclimates where fog, dew, and light rainfall are common. |
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