How do you calculate ponding time?

To determine the amount of infiltration from a rain storm of duration, tr, and intensity P you will have to first determine the time at which surface ponding occurs (Eqs. 4 & 5). If tr < tp or P < Ks then the amount of infiltration, F = Ptr and the infiltration rate, f = P. If td > tp, then you will have to use Eq.

What is Green Ampt equation?

The Green and Ampt equation (1911) is a half-empirical and half-theoretical model describing the soil water infiltration process, originally in homogeneous soil and later extended to layered soils [18,19].

What is the physical meaning of ponding time in infiltration?

‘Ponding time’ is the period from the beginning of rainfall until the occurrence of ponding. This model also can compute the variation in the infiltration capacity for constant or variable rainfall rates. A simple conceptual model is valuable for carrying out the stormwater runoff analysis.

How do you calculate infiltration capacity?

It is usually measured by the depth (in mm) of the water layer that can enter the soil in one hour. An infiltration rate of 15 mm/hour means that a water layer of 15 mm on the soil surface, will take one hour to infiltrate. In dry soil, water infiltrates rapidly.

What ponding means?

Ponding is the (typically) unwanted pooling of water, typically on a flat roof or roadway. Ponding water accelerates the deterioration of many materials, including seam adhesives in single-ply roof systems, steel equipment supports, and particularly roofing asphalt.

What are the factors affecting infiltration?

Factors Affecting Infiltration Capacity

• Texture of Soil. The texture of soil influence the rate of infiltration of water.
• Groundwater Table.
• Rainfall Intensity.
• Temperature.
• Quality of Water.
• Content of Soil Moisture.
• Agriculture.
• Human Activity.

What is suction head in soil?

The suction head, represented in millimeters, is the capillary attraction on the soil voids. It is large for fine grain soils such as clays and smaller for sandy soils.

What is hydraulic conductivity used for?

Hydraulic conductivity: Why you need it Hydrologists need hydraulic conductivity values for modeling, and researchers use it to determine soil health or to predict how water will flow through soil at different field sites.

What is ponding in hydrology?

Ponding. In hydrologic terms, in flat areas, runoff collects, or ponds in depression and cannot drain out. Flood waters must infiltrate slowly into the soil, evaporate, or be pumped out.

How do you solve infiltration?

Solution. The measured data are given in Columns 1, 3 and 4. Cumulative infiltration F is calculated by subtracting the cumulative runoff from the cumulative rainfall. Infiltration rate is then determined by dividing the F by the total duration of infiltration.

What are the methods of infiltration?

Infiltration rate usually is determined from field data. Many dif- ferent methods and types of equipment have been used for measuring infiltration rate, but the principal methods are flooding of basins or furrows, sprinkling (to simulate rain), and measuring water entry from cylinders (infiltrometer rings).

What is water ponding test?

What is a water ponding test? It’s a type of test for your bathroom floor to see if the waterproofing membrane underneath actually prevents water from seeping through and leaking into the ceiling below it. And a non-waterproofed grout allows bacteria to penetrate into its pores overtime.

How long does it take to solve equation for time?

When you divide 720m by 3m/s the meters cancels out and you are then left with time which would be 240 seconds. This equation though is just a manipulation of

How to solve for time rate and distance?

So if we flip it around, you get distance is equal to rate times time. So these are all saying the same things. And then if you wanted to solve for time, you could divide both sides by rate, and you get distance divided by rate is equal to time. And that’s exactly what we got.

What is the formula for time of concentration?

t= travel time (hr) L = flow length (ft) V = average velocity (ft/s) 3600 = conversion factor from seconds to hours. Time of concentration ( T c) is the sum of T tvalues for the various consecutive flow segments: TT T T ct t t m 12 K[eq. 3-2] where: T c= time of concentration (hr) m = number of flow segments

How is travel time and concentration of water determined?

Computation of travel time and time of concentration. Water moves through a watershed as sheet flow, shallow concentrated flow, open channel flow, or some combination of these. The type that occurs is a function of the conveyance system and is best deter- mined by field inspection.