Introduction to Land Use Land Cover (LULC) Maps

Graduate course, Tribhuvan University, College of Applied Sciences-Nepal , Hydrology Department, 2024

The terms land use and land cover are often used interchangeably, but each has its own distinct meaning. Land cover refers to the physical material found on the Earth’s surface, such as vegetation, urban infrastructure, water bodies, and bare soil. Identifying land cover forms the foundation for activities like thematic mapping and change detection analysis. On the other hand, land use refers to the purpose or function of the land, such as agriculture, wildlife habitat, recreation, or urban development.

When combined, the term Land Use/Land Cover (LULC) generally refers to the categorization or classification of both human activities and natural elements on the landscape, within a specified time frame. This classification is based on scientific and statistical methods using relevant source materials.

Land Cover vs. Land Use

Land cover is the physical material on the surface of the Earth, while land use describes how humans utilize the land for socio-economic activities. Both are crucial in understanding the environment, managing natural resources, and making informed decisions about urban planning, resource management, and conservation efforts.

Why Do We Need LULC Maps?

LULC maps play a vital role in planning, management, and monitoring programs at local, regional, and national levels. They are essential tools for understanding land utilization and can inform the creation of policies and programs necessary for sustainable development. These maps provide insight into the land’s current condition, helping stakeholders make informed decisions about land use and environmental protection.

For instance, ensuring sustainable urban development and curbing the haphazard expansion of cities requires an understanding of the current and past land use/land cover patterns. This can help authorities design planning models that maximize the use of available land in the most rational and optimal manner. By examining LULC maps, we can track changes in ecosystems and environmental conditions, which are critical for developing policies aimed at environmental conservation.

Example: Change Detection

A common application of LULC maps is change detection, which compares the land cover of a specific area at two different points in time. This can reveal patterns of urban sprawl, deforestation, agricultural expansion, and other environmental changes.

LULC Classification

LULC classification is one of the most widely used applications of remote sensing. The two most common approaches for classification are:

1. Unsupervised Classification

In this method, software analyzes the image without requiring the user to provide sample classes. The software groups pixels with common characteristics into classes using algorithms. The user specifies the number of output classes, but the software determines the classification.

Steps Involved:

The image is segmented based on its spectral properties.
Pixels are grouped into clusters, and the software assigns a class label.

2. Supervised Classification

In supervised classification, the user selects sample pixels that represent specific classes (such as forests, wetlands, or urban areas) and guides the software to classify all other pixels in the image. The user also sets the bounds for how similar other pixels must be to those training sites.

Steps Involved:

Select training areas (representative pixels of specific land classes).
Specify spectral properties (e.g., reflectance in different bands).
The software uses the training sites to classify all pixels in the image.

Types of LULC Classes

Here are some of the common LULC classes that are typically used in mapping:

Urban or Built-up Land: Residential, commercial, industrial, and mixed-use areas.
Agricultural Land: Cropland, pasture, orchards, and horticultural areas.
Rangeland: Herbaceous, shrub, and mixed rangelands.
Forest Land: Deciduous, evergreen, and mixed forests.
Water: Rivers, lakes, reservoirs, bays, and estuaries.
Wetland: Forested wetlands and non-forested wetlands.
Barren Land: Dry salt flats, beaches, sandy areas, and exposed rock.
Transitional Areas: Areas in transition between land types.
Perennial Snow or Ice: Snowfields and glaciers.

Geospatial Data and LULC

With advancements in remote sensing and geographic information systems (GIS), the availability of spatial data has increased significantly. Geospatial data now includes not only LULC maps but also attributes such as socioeconomic data, environmental conditions, and more.

Remote sensing, particularly through the use of satellite imagery, provides valuable, real-time information about vegetation growth, which can be quantified using indices like the Normalized Difference Vegetation Index (NDVI). NDVI uses reflectance data from visible (red) and near-infrared (NIR) bands to assess the health and density of vegetation over large areas.

Applications of LULC Maps

LULC maps have diverse applications across many fields, including:

Natural Resource Management: Monitoring and managing forests, wetlands, water resources, and soil.
Wildlife Habitat Protection: Identifying and protecting critical habitats.
Baseline Mapping for GIS Input: Providing a foundational dataset for further geographic analysis.
Urban Expansion / Encroachment: Tracking the growth of urban areas and the encroachment on natural resources.
Routing and Logistics Planning: Aiding in planning for infrastructure development, such as roads and utilities.
Damage Delineation: Mapping damage from natural disasters such as floods, fires, or tornadoes.
Legal Boundaries: Assisting with tax assessment and property boundary delineation.

Summary

Land Use/Land Cover (LULC) mapping is crucial for understanding and managing both natural resources and human activities. It provides a comprehensive categorization of the physical land cover and how it is used, which helps guide policies for sustainable development. LULC maps are generated through various classification methods, such as unsupervised and supervised classification, and have broad applications in fields like urban planning, resource management, and disaster response.

As the availability of geospatial data grows, the importance of LULC maps will continue to rise, making them essential tools for making informed decisions about the environment and land use planning.

Bishwa Prakash Puri