1) arithmetic mean – This technique calculates areal precipitation using the arithmetic mean of all point or area measurements considered in the analysis. 2) Isohyetal Analysis – This is a graphical technique that draws estimated lines of equal rainfall over an area based on point measurements.
What are the methods of calculating average precipitation?
Measuring the average amount of precipitation: 3 methods | Atmosphere | Geography
The Arithmetic Mean Method: The simplest of all is the arithmetic mean method, which takes an average of all precipitation amounts as shown in Fig.
The Thiessen polygon method:
The Isohyetal Method:
What methods are there to determine the average amount of precipitation over an area?
Estimation of the average amount of precipitation
Arithmetic Mean Method: This is the simplest method where the average precipitation amount is obtained by taking the sum of the precipitation amounts (eg1P2P3P4…………….
Polygon method according to Theissen:
Which 4 methods for areal precipitation estimation are there?
This problem is illustrated below where avg P needs to be estimated over the entire basin from measured 1P, 2P, 3P and 4P. We will discuss four methods: 1) Arithmetic Mean, 2) Theissen Polygons, 3) Isohyetal Method and 4) Grid Method.
How many methods are used to determine average rainfall by drainage basin?
Explanation: When there are more basins, three of the following methods are used to determine the average rainfall as a function of basin area. They are the arithmetic mean method, the Thiesson method and the Iso-Hyetol method.
Which method provides an accurate estimate of the average rainfall in the catchment area of hilly area?
The isohyetal method is used to estimate mean precipitation over an area by drawing lines of equal precipitation.
What is the Thiessen polygon method?
A method for assigning area importance to point precipitation values. These bisecting lines form a series of polygons, each polygon containing a station. The precipitation value measured at a station is assigned to the entire area of the enclosing polygon.
What methods are there to estimate missing precipitation data?
The following methods are most commonly used to estimate the missing records.
Simple arithmetic method.
method of normal ratio.
Modified normal ratio method.
Inverse distance method.
Linear programming method.
How is the amount of precipitation measured?
The standard instrument for measuring precipitation is the 203 mm (8 inch) rain gauge. This is essentially a circular 203mm diameter funnel that collects the rain in a graduated and calibrated cylinder. The measuring cylinder can record up to 25 mm of precipitation.
What is the average areal precipitation?
Precipitation in a given area, expressed as the average depth of liquid water over the area; the average amount of precipitation over a given area, calculated on time scales on a storm, seasonal, or annual basis.
What is the best method for determining mean annual precipitation?
To determine the mean annual precipitation in a catchment area, the isohytated method is the best method.
What are the 8 types of precipitation?
The different types of precipitation are:
Rain. Most commonly observed, drops larger than drizzle (0.02 inch / 0.5 mm or more) are considered rain.
drizzle. Fairly uniform precipitation consisting entirely of very densely packed fine droplets.
Ice pellets (sleet)
Small hail (snow pellets)
grains of snow.
Why is the Isohyetal method better than the Thiessen polygon method?
Answer: The isohyetal method is considered more accurate than the Thiessen polygon method or the gridpoint technique for estimating precipitation totals because it takes into account the effects of local features.