How can GIS help identify areas at risk of landslides?

1 What is GIS?

GIS stands for Geographic Information System, which is a computer-based system that can store, manipulate, analyze, and display spatial data. Spatial data are any data that have a geographic location, such as coordinates, addresses, boundaries, or features. GIS can integrate different types of spatial data, such as maps, aerial photos, satellite images, census data, environmental data, and field surveys, and perform various operations on them, such as overlaying, buffering, querying, measuring, and modeling. GIS can also produce visual outputs, such as maps, charts, graphs, and animations, that can help communicate complex spatial information.

2 How can GIS help identify areas at risk of landslides?

One of the main applications of GIS in landslide risk assessment is to create landslide susceptibility maps. These are maps that show the likelihood of landslides occurring in a given area based on the combination of various factors that affect landslide occurrence. For example, GIS can use digital elevation models (DEMs) to derive slope, aspect, curvature, and other topographic parameters that influence landslide susceptibility. GIS can also use other spatial data, such as soil type, land use, vegetation cover, rainfall intensity, and seismic activity, to assign weights or scores to each factor and calculate a composite index of landslide susceptibility. GIS can then classify the index into different levels of susceptibility and display them on a map.

Another application of GIS in landslide risk assessment is to create landslide hazard maps. These are maps that show the probability and magnitude of landslides occurring in a given area over a certain period of time. For example, GIS can use historical records of landslide events, such as location, date, size, type, and trigger, to estimate the frequency and severity of future landslides. GIS can also use statistical or deterministic models to simulate the initiation, movement, and impact of landslides under different scenarios of rainfall, earthquake, or human intervention. GIS can then represent the hazard as a spatial distribution of landslide probability or intensity on a map.

A third application of GIS in landslide risk assessment is to create landslide risk maps. These are maps that show the expected consequences or losses of landslides occurring in a given area for a certain population or asset. For example, GIS can use spatial data on population density, building characteristics, infrastructure networks, economic activities, or environmental values to estimate the exposure and vulnerability of people or properties to landslides. GIS can also use spatial data on landslide susceptibility and hazard to estimate the likelihood and magnitude of landslides affecting the exposed and vulnerable elements. GIS can then combine the exposure, vulnerability, and hazard to calculate the risk as a spatial distribution of expected damage or loss on a map.

3 What are the benefits of using GIS for landslide risk assessment?

Using GIS for landslide risk assessment offers several advantages, such as its ability to integrate and analyze large and diverse spatial data from multiple sources and scales. This can improve the accuracy and completeness of the assessment. Additionally, GIS can automate and standardize the data processing and modeling procedures, saving time and resources while enhancing the consistency and reproducibility of the assessment. Moreover, it can generate spatial outputs that can help interpret and communicate the assessment results, thereby supporting decision-making and planning processes for landslide risk reduction.

4 What are the challenges of using GIS for landslide risk assessment?

Using GIS for landslide risk assessment can be challenging due to the need for reliable and updated spatial data, which may be scarce or inaccessible in some areas. Additionally, complex and uncertain data processing and modeling methods can lead to errors or biases that may affect the quality of the assessment results. Furthermore, the expertise and judgment of the users can vary depending on their skills, knowledge, and objectives, influencing the selection and application of the data and methods.

5 How can you learn more about GIS for landslide risk assessment?

If you are interested in learning more about GIS for landslide risk assessment, the United Nations Office for Disaster Risk Reduction (UNDRR) has published a guide on how to use GIS for disaster risk assessment, including landslides. The World Bank has also developed a tool called ThinkHazard! which provides hazard information, including landslides, for any location in the world. The International Consortium on Landslides (ICL) has also organized a series of webinars on landslide risk assessment and management. All of these resources can be accessed online.