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This differential equation states that the total change in oxygen deficit (D) is equal to the difference between the two rates of deoxygenation and reaeration at any time. The Streeter–Phelps equation, assuming a plug-flow stream at steady state is then
The Penman equation describes evaporation (E) from an open water surface, and was developed by Howard Penman in 1948. Penman's equation requires daily mean temperature, wind speed, air pressure, and solar radiation to predict E. Simpler Hydrometeorological equations continue to be used where obtaining such data is impractical, to give comparable results within specific contexts, e.g. humid vs ...
[2] [3] In hydrology, a water balance equation can be used to describe the flow of water in and out of a system. A system can be one of several hydrological or water domains, such as a column of soil, a drainage basin, an irrigation area or a city. The water balance is also referred to as a water budget. Developing water budgets is a ...
Vapour pressure-deficit, or VPD, is the difference (deficit) between the amount of moisture in the air and how much moisture the air can hold when it is saturated. Once air becomes saturated, water will condense to form clouds, dew or films of water over leaves. It is this last instance that makes VPD important for greenhouse regulation. If a ...
The concept of water deficit, as developed by Stocker in the 1920s, [6] [7] [8] is a useful index of the balance in the plant between uptake and loss of water. Slight water deficits are normal and do not impair the functioning of the plant, [9] while greater deficits disrupt normal plant processes.
The recommended daily amount of drinking water for humans varies. [1] It depends on activity, age, health, and environment.In the United States, the Adequate Intake for total water, based on median intakes, is 4.0 litres (141 imp fl oz; 135 US fl oz) per day for males older than 18, and 3.0 litres (106 imp fl oz; 101 US fl oz) per day for females over 18; it assumes about 80% from drink and 20 ...
The Holliday-Segar formula is a formula to help approximate water and caloric loss (and therefore the water requirements) using a patient's body weight. [1] Primarily aimed at pediatric patients, the Holliday-Segar formula is the most commonly used estimate of daily caloric requirements. [2]
The SPEI accounts not only for precipitation deficit but also for the role of the increased atmospheric evaporative demand on drought severity. [5] Evaporative demand is particularly dominant during periods of precipitation deficit. The SPEI calculation requires long-term and high-quality precipitation and atmospheric evaporative demand datasets.