# How do you calculate rainfall intensity?

## How do you calculate rainfall intensity?

Formula Of Rainfall Intensity The intensity of rainfall (p) in mm/hr is given by the following general formula: p = 254a / (t+b) mm/hr Where, t = Duration of storm in minutes, a and b are constants. The following value of a and b are considered adequate. a = 30 and b = 10 when t is 5 to 20 minutes.

How do you calculate rainfall depth and intensity?

Rainfall intensity is often Rainfall Depth over a particular time. You need to accumulate the rainfall data for the the time step you are interested and then divide by that time. If you have rainfall intensity already, just multiply by the time step to get the depth.

### How is duration of rainfall intensity calculated?

Once this is done, the equation we will have two equations relating time to precipitation for the specific MSP. Then, I = P/T*60 can be used to determine the rainfall intensity “I” for any time of concentration “T” between 5 and 60 minutes.

How many mm rainfall in Mumbai today?

Today’s Weather We expect around 5.3 mm of precipitation to fall and cloud covering 42% of the sky, the humidity will be around 73%.

## How do you calculate rainfall intensity in Excel?

The Excel formulas in the spreadsheet are set up to calculate the constants, a and b, in the equation i = a/( d + b ), by linear regression of 1/i vs d. Then the design rainfall intensity is calculated with the equation i = a/( d + b ) using the calculated values for a and b.

How do you calculate rainfall intensity from annual rainfall data?

It is calculated by dividing the depth by the duration and is simply a measure of the ‘heaviness’ of the rainfall.

### What is the total rainfall in Mumbai?

Mumbai recorded 3,163.5 mm rainfall from June 1 to September 30 as against the seasonal average of 2,205.8 mm. Last year, Mumbai recorded 3,686.8 mm rainfall from June 1 to September 30 as against the seasonal average of 2,205.8 mm, which was also the second wettest monsoon for the city.

What is average rainfall in Mumbai?

95.35 inches
Mumbai’s climate can be best described as moderately hot with high level of humidity. Its coastal nature and tropical location ensure temperatures do not fluctuate much throughout the year. The mean average is 27.2 °C and average precipitation is 242.2 cm (95.35 inches).

## Is 7.5 mm a lot of rain?

Moderate rain – rain rate of fall is 2.6 to 7.5 mm/h (0.1 to 0.3”/hr) or 0.04 to 0.125 mm/min (0.0017 to 0.005”/hr), which for a 0.1 mm resolution rain gauge equals 26 to 75 full tipping buckets per hour (26 to 75 pulses/hr).

How do you use Horton equations?

The original Horton equation was given as follows. (1) f ( t ) = f c + ( f 0 – f c ) e – k t where f0 is the initial value of infiltration capacity (mm/h) at the beginning of rainfall; k is the soil-specific decay constant.

### What is Philip’s equation?

The equation was reformulated as / – cKf = l/2Sr “*, where / is the infiltration rate,S the sorptivity, t the time, Kf the field-measured final infiltration rate, and c, a coefficient relating Kf to the Philip parameterA.

Why there is so much rain in Mumbai?

Reason behind Mumbai’s unseasonal rainfall “The rainfall in the city in the winter season is owing to a cyclonic circulation over the south-east Arabian Sea and adjoining Lakshadweep area which as of Wednesday was over south-east and adjoining east-central Arabian sea,” said Shubhangi Bhute, scientist at IMD, Mumbai.

## Why does Mumbai get heavy rainfall?

What is the highest monthly rainfall in Mumbai?

On average, July is the wettest month with 713 mm (28.1 inch) of precipitation. On average, March is the driest month with 0 mm (0 inch) of precipitation.

### What is a high rainfall intensity?

Heavy rain — when the precipitation rate is > 7.6 mm (0.30 in) per hour, or between 10 mm (0.39 in) and 50 mm (2.0 in) per hour. Violent rain — when the precipitation rate is > 50 mm (2.0 in) per hour.

How much mm is heavy rainfall?

Heavy rain: Greater than 4 mm per hour, but less than 8 mm per hour. Very heavy rain: Greater than 8 mm per hour. Slight shower: Less than 2 mm per hour. Moderate shower: Greater than 2 mm, but less than 10 mm per hour.

## What is K in Horton’s equation?

K = decay time constant. At any point in time during the storm, the actual infiltration rate must be equal to the smaller of the rainfall intensity i(t) and the infiltration capacity fcapac. Thus the Horton model for abstractions is given by equations [7-22] and [7-23]. for i > fcapac.

What is the average rainfall intensity in Mumbai?

( Figu re 4 and Figu re 5 respectively) is 117. 65 mm/hr and 117.39 m m/hr respectively. However, as per past rainfall rec ord, Mumbai has experie nced 190 mm/ hr rainfal l intensity i n July 2005. Thus the IDF curves deve l- does not show the proper res ults in the recently changing hydrologic condi tions for the Mumbai ci ty. In view of

### How do you calculate the intensity of rainfall?

The intensity of rainfall is greater when shorter periods are considered while it is lower when large periods are considered. The intensity of rainfall (p) in mm/hr is given by the following general formula: p = 254a / (t+b) mm/hr Where, t = Duration of storm in minutes, a and b are constants. a = 30 and b = 10 when t is 5 to 20 minutes.

Can intensity duration frequency (IDF) curves be derived for Mumbai rainfall?

For the appropriate design and planning of urban drainage system in an area, Intensity Duration Frequency (IDF) curves for given rainfall conditions are required. The aim of the present study is to derive the IDF curves for the rainfall in the Mumbai city, Maharashtra, India.

## How many rain gauge stations were there in Mumbai before 2005 floods?

Before 26thJuly 2005 floods, there were only two rain gauge stations in Mumbai. The observed daily rainfall data for a period of 108 years (1901 to 2008) from Colaba rain gauge station, and 58 years (1951 to 2008) from the Santacruz rain gauge station were used in deriving the IDF curves using the equation given by Kothyari.