3.2 Data Preparation:
Flood sensitive area
We used the source data for all parameters except flood sensitivity. To create a flood severity map, we downloaded Sentinel-2 data from August 16, 2018, from the Sentinel Hub. This data captured the flood that occurred in Lalitpur on August 15, 2018. We then calculated the NDVI using the NIR and Red bands. We considered NDVI values less than 0 as water, indicating the flooded areas. We also properly monitored the unflooded areas. Finally, we used the output for the study.
Slope calculation:
The initial step is to work with a Digital Elevation Model (DEM), which provides information about the elevation values of the terrain across the study area. This raw DEM may contain sinks or depressions, which are areas where water would accumulate or flow inward, creating anomalies in the elevation data. Fill Sinks: Filling sinks in the DEM is a preprocessing step that aims to remove these depressions and ensure a continuous and consistent surface. By filling sinks, you are eliminating data anomalies and creating a more accurate representation of the terrain. This is crucial for subsequent terrain analysis. Slope Calculation: Once the sinks are filled, the resulting filled DEM provides a more reliable foundation for slope calculations. Slope calculations involve determining the steepness of the terrain at each location, which requires measuring the rate of elevation change in the steepest direction. By having a continuous and accurate representation of the terrain (after filling sinks), the slope calculation becomes more meaningful and freer from division by zero errors that could arise in the presence of sinks or flat areas.
Proximity CBD data:
The boundary of the CBD was digitized and converted into a point layer representing the CBD location. The buffer analysis tool in QGIS was employed to create buffer zones around the CBD point layer. Distances of 500 meters, 1000 meters, 1500 meters, 2000 meters, and more were chosen to represent different proximity ranges from the CBD. The buffer zones were generated by setting the respective distance values while keeping the buffer segment options appropriate for the study area.
Proximity to Landfill:
The boundary of the land fill was digitized and converted into a point layer representing the landfill location. The buffer analysis tool in QGIS was employed to create buffer zones around the landfill point layer. Distances of 500 meters, 1000 meters, 1500 meters, 2000 meters, and more were chosen to represent different proximity ranges from the landfill site. The buffer zones were generated by setting the respective distance values while keeping the buffer segment options appropriate for the study area.
Proximity to Infrastructure:
The point data of the infrastructures (education and health institution) was digitized representing the infrastructure location. The buffer analysis tool in QGIS was employed to create buffer zones around the infrastructure point layer. Distances of 500 meters, 1000 meters, 1500 meters, 2000 meters, and more were chosen to represent different proximity ranges from the infrastructure. The buffer zones were generated by setting the respective distance values while keeping the infrastructure segment options appropriate for the study area.
Proximity to Road:
The primary, secondary, and tertiary road data was digitized representing the road network. The buffer analysis tool in QGIS was employed to create buffer zones around the road network. Distances of 500 meters, 1000 meters, 1500 meters, 2000 meters, and more were chosen to represent different proximity ranges from the road network. The buffer zones were generated by setting the respective distance values while keeping the road network segment options appropriate for the study area.
Proximity to Brick factory:
The point data of the brick factory was digitized representing the brick factory location. The buffer analysis tool in QGIS was employed to create buffer zones around the brick factory point layer. Distances of 500 meters, 1000 meters, 1500 meters, 2000 meters, and more were chosen to represent different proximity ranges from the brick factory. The buffer zones were generated by setting the respective distance values while keeping the brick factory segment options appropriate for the study area.
3.3 Reclassification Based on Normalized Weight:
Table 3
Rank
Suitability grade
|
Very high opportunity
5
|
High opportunity
4
|
Moderate opportunity
3
|
Low opportunity
2
|
Very low opportunity
1
|
Land Cover (Luan, Renzhi, & Sicheng, 2021)
|
Bare Ground
|
Grass, Shrub
|
Built-up area
|
Trees, Crops
|
Water
|
Slope (Luan, Renzhi, & Sicheng, 2021)
|
0–17
|
17–33
|
33–48
|
48–67
|
67–89
|
Terrain Elevation (Luan, Renzhi, & Sicheng, 2021)
|
0-446
|
446–1016
|
1016–1589
|
1589–2000
|
2000–2375
|
Population Density
|
Very low density
|
Low density
|
Moderate density
|
High density
|
Very high
density
|
Proximity to
Infrastructure
|
< 500
|
500–1000
|
1000–1500
|
1500–2000
|
> 2000
|
Proximity to Road (Luan, Renzhi, & Sicheng, 2021)
|
< 500
|
500–1000
|
1000–1500
|
1500–2000
|
> 2000
|
Proximity to Brick Factory
|
> 2000
|
1500–2000
|
1000–1500
|
500–1000
|
< 500
|
Proximity to Landfill
|
> 2000
|
1500–2000
|
1000–1500
|
500–1000
|
< 500
|
Proximity to Sensitive Zone (Flood)
|
Not sensitive area
|
Mildly sensitive area
|
Moderately
Sensitive area
|
Highly sensitive area
|
Extremely sensitive area
|
Proximity to CBD (Luan, Renzhi, & Sicheng, 2021)
|
< 500
|
500–1000
|
1000–1500
|
1500–2000
|
> 2000
|
The most suitable areas for urban development are those with bare ground, grass, or shrub cover, a slope of 0–17 degrees, a terrain elevation of 0-446 meters, low population density, proximity to infrastructure, proximity to the CBD, and distance from brick factories and landfills because these areas are relatively flat, have low population densities, and are convenient for residents and businesses (Howley, Scott, & Redmond, 2009). They are also less polluted and have a better quality of life.
The least suitable areas for urban development are those with built-up areas, trees, or crops, a slope of 17–89 degrees, a terrain elevation of 446–2375 meters, high population density, distance from infrastructure, proximity to brick factories and landfills, and location in flood sensitivity zones. These areas are already developed, may be difficult to develop, and may have traffic congestion, noise pollution, pollution, and flooding (Luan, Renzhi, & Sicheng, 2021).
The results of the proximity analysis can be used to inform decisions about where to locate new urban development projects. By considering the factors that were found to be most important, planners can help to ensure that new development is sustainable and contributes to the overall well-being of the community.
Here are some additional details about the factors that were considered in the proximity analysis:
-
Land cover: The land cover provides aggregate information on land. For example, a forest is a landcover but the type of the forest is land use. In this study as built-up area, water bodies, agriculture and forest land are given less value as compare to the barre land to protect the agriculture, forest area where as built-up area already contain settlement.
-
Slope: Slope is the angle of the land surface. Areas with a slope of 0–17 degrees are considered to be flat. Areas with a slope of 17–89 degrees are considered to be hilly. Areas with a slope of 89 degrees or more are considered to be mountainous.
-
Terrain elevation: Terrain elevation is the height of the land surface above sea level. Areas with a terrain elevation of 0-446 meters are considered to be low-lying. Areas with a terrain elevation of 446–2375 meters are considered to be mountainous.
-
Population density: Population density is the number of people per square kilometer. Areas with low population densities are considered to be more desirable for urban development than areas with high population densities.
-
Proximity to infrastructure: Infrastructure includes roads, schools, hospitals, and other essential services. Areas that are close to infrastructure are more convenient for residents and businesses.
-
Proximity to brick factories and landfills: Brick factories and landfills can pollute the environment and have a negative impact on the quality of life. Areas that are close to brick factories and landfills are less desirable for urban development.
-
Proximity to flood sensitivity zones: Flood sensitivity zones are areas that are prone to flooding. Areas that are located in flood sensitivity zones are less desirable for urban development.