LAND USE LAND COVER
(CHORO-CHROMATIC METHOD)
DEFINITION:
The word Chorochromatic consist of two Greek words, namely “chora” meaning “region”
and “chroma” meaning “colour”, the full meaning of which is “Colour of the region”. This
map is known by multiple names such as colour-patch map, area class, qualitative class or
mosaic map etc.
A Chorochromatic map is a type of thematic map where-without considering any form of
numerical or statistical information within the boundaries of the respected administrative unit,
first outlined single and multiple spatial patterns of the ground surface and then displayed
with colour symbols such as tints or colours. With the help of such map landuse components
or landuse patterns, soil groups, vegetation zones, crop regions etc are easily displayed.
PROBLEM:
To prepare a thematic representation of spatial information in polygon features
OBJECTIVE:
To identify the different spatial information
DATA:
The data has been provided by Department of Geography, NEHU
METHODOLOGY:
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The given toposheet is georeferenced/registered into QGIS
Select an area from the given toposheet and then create a shapefile for the study area
Create different shapefile for each feature such as rivers, settlements, forest area etc
and the start digitizing using polygon
After digitization, go to properties
symbology and assign different colours for
different features
Go to open attribute
open field calculator, and calculate the area
Open new print layout and add the map, legend, scale, title and north arrow
Export the final output
ANALYSIS AND INTERPRETATION
The following study area was taken from the toposheet no. G46H12_78N12 and was
surveyed in 1987-88. The longitude of the study area is 91040N-91045N and latitude is
2607’30E-26012’30E
Here in the study all the features are being represented by polygons and it represent spatial
information like tank, swamps, rivers, forests, settlements, barren land and cultivated land.
River: The river Brahmaputra lies in the northern part of the study area flowing from east to
west direction and covering an area of 13 sq.km. River Brahmaputra plays a vital role in our
ecosystem and provide numerous benefits to both humans and the environment such as fresh
water supply, transportation, water for irrigations, bio-diversity and many more.
Settlement: settlements are mostly located in and around the river bank and covers roughly
30sq.km. The settlement are located near river because it provides a consistent and easily
accessible water resource for human settlement and agriculture. River also provides natural
resources such as fish, freshwater for drinking and energy potential through hydropower
generation. It also serves as an important transport routes. Settlement near river has easy
access to water-based transportation allowing people to transport goods and engage in trade
with other communities.
Cultivated land: River often has floodplains adjacent to their banks. These floodplains
received periodic floods which deposit rich nutrient sediments, farmers take advantage of
these and practice agriculture. Cultivating crops near river can lead to higher agricultural
productivity and better yield. Floodplains near Brahmaputra are one of the most fertile lands.
Forests: The reserved forests can be found in the northwestern and the southern part of the
study area covering an area of about 12sq.km. The forest is incredibly valuable ecosystem
that offer wide range of benefits such as biodiversity conservation, recreational and tourism,
carbon sink and many more.
Wet Land: The wetland, covering a total area of 5sq.km can be found in the northern, western
and some patches can be found in the eastern side of the study area, typically in low-lying
areas with high water content dominated by trees, shrubs and other vegetations. Wetland
despite their challenging and inhospitable conditions provide numerous benefits such as
storing of carbon, ground water recharge zone and water filtration, flood control etc.
Tank: The tanks is found in the northern and western part of study are. They formed by rivers
or groundwater and serves as water supply, irrigation, flood control, biodiversity and
ecosystem support and many more
Barren Land: The Barren land can be seen in the eastern and southern parts of the study area,
covering an area of 4sq.km. It is characterized by low-growing scrubs, occurs in arid or
semi-arid climate where the availability of water is limited.
CONCLUSION:
The chorochromatic map, through its different shades of colours enable the representation of
different spatial information/phenomena and its relationship. By employing chorochromatic
map we can organize and analyse data in a structured and meaningful way, enabling better
decision making and understanding of the area around us