The difference between a given surface and the actual time of advance of water in a surface irrigation event is known as ____________.
Surface Irrigation: Understanding Intake Opportunity Time
In surface irrigation, water advances across the field over time. The duration for which water remains on the soil surface at any given point, allowing it to infiltrate, is termed the intake opportunity time.
This is the time available for the soil to absorb water at that specific location during the irrigation event.
Analysis of Options
- Time of concentration: Refers to the time taken for water from the furthest point of a catchment area to reach the outlet in hydrology. This doesn't fit the context of irrigation advance on a surface.
- Lag time: The time delay between a cause (like rainfall) and its effect (like peak streamflow). Not relevant here.
- Time to peak: The time to reach the maximum flow rate in a hydrograph. Not relevant to the duration of water contact on the soil surface during advance.
- Intake opportunity time: This correctly describes the period water is available for infiltration at a specific location as it advances across the surface. It is directly influenced by the water's advance time and subsequent recession.
Therefore, the difference between the presence of water on a given surface area and the time it takes for water to fully advance is best described by the period water has to soak in, which is the intake opportunity time.
Important Questions from Surface Irrigation Methods
- Uniformity of irrigation is checked in a border strip by measuring water penetration depth at 16 equally spaced stations along a border strip. The depths of penetration of water recorded in mm are as follows:
$0.65, 0.83, 0.79, 0.87,$
$0.67, 0.85, 0.86, 0.68,$
$0.88, 0.77, 0.73, 0.59,$
$0.89, 0.63, 0.72, 0.70$
The distribution uniformity low-quarter (DULQ) (in fraction) is ________
(Rounded off to two decimal places) - Furrows of 120 m length with 0.5% slope are made at 90 cm spacing. The maximum non-erosive stream flow rate is applied in a furrow that takes 1.0 hour to reach the lower end. Then this flow rate is reduced to half of its size and, subsequently, continued for another 1.0 hour. The average depth of applied water is ________ cm.
Graded furrows of 80 m length and 0.75 m spacing are used for irrigating a field with an initial furrow stream of 100 L $min^{-1}$. The initial furrow stream flow reaches the lower end of the field in 40 min. Thereafter, the furrow stream flow is reduced to 30 L $min^{-1}$ and the cutback stream flow is continued for 1 hour. The average depth of irrigation over the field in cm will be ______________.
- A border strip of $8 \times 250 \text{ m}$ is being irrigated by a border stream of $50 \text{ lps}$. The infiltration capacity of the soil is $25 \text{ mm h}^{-1}$ (assumed to be constant throughout the period of irrigation). The average depth of the advancing sheet of water over the land is $70 \text{ mm}$. The time required to irrigate the border strip, in minutes, will be
