1. Distributional Maps
Complete solutions to the Exercise. Maharashtra State Board (Balbharati), Grade 9 Geography.
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Exercise
(1) The main aim of distributional maps is to show location.
Wrong. The main aim of distributional maps (thematic maps) is to show the distribution of variables (like temperature, rainfall, population, etc.) in a particular region. Location is typically shown by standard physical or political maps.
(2) In choropleth maps, only one value is assigned to the sub-administrative unit.
Right. In the choropleth method, the data used is obtained through measurement or surveying, and a single average value or category is assigned to one entire sub-administrative unit.
(3) In choropleth maps, colours/tints do not change according to the values of the variables.
Wrong. In choropleth maps, the shades or tints specifically change according to the values. The patterns or colours become progressively darker with the increasing values of the given variable.
(4) Choropleth maps are used to show altitudes.
Wrong. Altitude is a continuous variable. Continuous variables are best represented using the isopleth method (using contour lines), not the choropleth method.
(5) Isopleth maps are used to show population distribution.
Wrong. Population distribution is discontinuous and discrete, so it is best shown using the dot method or choropleth method. Isopleth maps are used exclusively for continuous variables like temperature or rainfall.
(6) In dot method, every dot should have an appropriate scale.
Right. To show distribution accurately through the dot method, the value of a single dot has to be determined carefully by considering the lowest and highest values of the variable and the scale of the map.
(7) Isopleth maps are not made using isolines.
Wrong. Isopleth maps are precisely made using lines joining places of equal values. These lines of equal value are called isolines or isopleths.
(8) Distribution of various geographical elements can be shown using dot method.
Right. The dot method is highly suitable for various geographical elements that are freely scattered across a region, such as population or distribution of domestic animals.
(1) Explain the use and types of distributional maps.
Use of distributional maps: They are special-purpose (thematic) maps primarily used to explain the distribution of various geographical variables in a region, such as temperature, rainfall, and population. They easily bring out patterns of distribution that would be hard to understand from tables of raw statistical data.
Types of distributional maps: There are three main methods used to draw these maps:
- Dot method: Uses dots of a pre-determined uniform value to show the distribution of freely scattered variables (e.g., population distribution).
- Choropleth method: Uses shades or tints of colours, or black-and-white patterns, to show data values grouped into classes and assigned to specific sub-administrative units (e.g., population density).
- Isopleth method: Uses lines joining points of equal values (isolines) to show continuous variables (e.g., altitude, temperature, average annual rainfall).
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(2) Differentiate between choropleth and isopleths methods.
| Choropleth Method | Isopleth Method |
|---|---|
| Data is assigned and plotted according to specific sub-administrative units (like talukas or districts). | Data is point-related; administrative boundaries are not taken into consideration. |
| Suitable for discrete or discontinuous variables, such as population density or agricultural yield. | Suitable for continuous variables, such as temperature, rainfall, or altitude. |
| Uses colour tints, shades, or black-and-white patterns to represent different data classes. | Uses isolines (lines joining places of equal values) to represent the data. |
| A single average value is assigned to the entire unit, so variations within that specific unit are not shown. | Shows natural trends and gradients (whether the change is steep or gentle) irrespective of boundaries. |
(3) Explain with reasons the method which is best suited to show the distribution of population in a region.
The Dot method is the best suited method to show the distribution of population in a region.
Reasons:
- Population is a variable that is freely scattered across a region rather than being uniform.
- The dot method allows for highly accurate representation by determining a specific value for each dot (for example, 1 dot = 10,000 people).
- It accurately reflects real-world patterns, showing exactly how population concentrates densely in cities (shown by larger circles) or scatters loosely in rural areas (shown by individual dots).
- It naturally incorporates physical factors; when placing dots, physiography, water sources, and transport systems are considered, giving a realistic visual pattern of where people actually live.
- (1) Talukawise wheat production in the district — Dot method or Choropleth method
- (2) Distribution of the altitude of the land in the district — Isopleth method
- (3) Distribution of domestic animals in the State — Dot method
- (4) The distribution of population density in India — Choropleth method
- (5) Temperature distribution in Maharashtra State — Isopleth method
(1) Which method has been used to show the distribution of population in the district?
The dot method has been used to show the distribution of population in the district.
(2) Explain the directionwise distribution of population from dense to sparse.
The population is densely distributed in the eastern and north-eastern parts of the district (such as Hatkanangale, Shirol, and Karvir). It becomes gradually sparser towards the western and southern parts of the district.
(3) What is the population shown by the largest circle? Which place is that?
The population shown by the largest circle is Twenty Lakhs (20,00,000). That place is Kolhapur city (Karvir Taluka).
(4) Which Taluka has the least population?
Gaganbavada taluka has the least population, as it has the fewest dots.