PROJECT 8: MULTICRITERIA DECISION ANALYSIS FOR SUITABILITY ANALYSIS

One of the major challenges in waste management is identifying an appropriate site for the disposal of municipal solid waste (MSW), a task that demands careful consideration of multiple factors and constraints. Landfill siting is a complex process that requires the integration of environmental, economic, and social criteria, alongside compliance with regulatory frameworks and the analysis of various spatial datasets. Geographic Information Systems (GIS) combined with Multicriteria Decision Analysis (MCDA) provide a powerful and systematic approach to address this complexity. By enabling the evaluation and comparison of potential sites based on multiple weighted criteria, MCDA ensures a more objective and informed decision-making process. This integration of GIS and MCDA not only facilitates the identification of optimal landfill locations but also minimizes environmental impacts and enhances public acceptance, making it an invaluable tool for sustainable waste management practices.

The suitability mapping process for landfill placement in the Selangor River Basin is critical because of the basin's environmental and socio-economic importance. The Selangor River serves as a vital water source for the region, and improper landfill siting could lead to contamination of this resource, affecting both ecosystems and human populations. By using tools like GIS and MCDA to identify suitable locations, potential environmental hazards such as leachate leakage or pollution can be minimized. Additionally, proper siting helps balance economic development and environmental conservation, ensuring sustainable waste management while safeguarding the basin's role as a key natural asset for the region. This approach also promotes community acceptance and regulatory compliance, reducing the risk of future conflicts. These classifications are based on a Multicriteria Decision Analysis (MCDA) framework, which combines several weighted spatial criteria which are Elevation (8%), Slope (8%), Soil Type (18%), Land Use (20%), Proximity to Water Bodies (20%), Proximity to Residential Areas (20%), and Proximity to Roads (6%) to determine the optimal landfill sites.

ELEVATION (8%)

The image above shows the map extraction for elevation. the legend shows the elevation rate. Elevation plays a significant role in determining the suitability of landfill sites, as it influences factors such as flooding risk, waterlogging, and overall environmental impact. Areas with elevations below 1000 meters were deemed unsuitable due to their high susceptibility to flooding, waterlogging, and potential contamination of nearby water resources. Elevations between 1000-1500 meters were assigned moderate suitability scores because they provide a balance between accessibility and reduced flood risk, although they may still be prone to occasional environmental challenges. In contrast, elevations above 1500 meters were ranked as the most suitable for landfill placement. These higher elevations are generally more isolated, minimizing potential human and ecological disturbances. Additionally, the reduced likelihood of flooding and lower water table levels at these elevations decrease the risk of leachate contamination, making them more environmentally viable for long-term waste disposal.

SLOPE (8%)

Slope is a critical factor in landfill site selection, as it directly impacts the stability, construction feasibility, and long-term management of the landfill. Gentle slopes ranging from 0-5 degrees were assigned the highest suitability scores because they provide a stable foundation for landfill construction, minimizing risks of landslides, structural failures, or uneven settlement. These slopes also facilitate efficient waste compaction and leachate management by preventing excessive runoff. On the other hand, slopes greater than 15 degrees were classified as unsuitable due to the significant challenges they pose. Steeper slopes increase the risk of erosion, which can lead to leachate contamination of surrounding areas and destabilization of landfill liners. Additionally, constructing and maintaining landfills on steep terrain is technically complex and cost-intensive, making such locations impractical for sustainable waste management. Moderate slopes (5-15 degrees) may be considered with additional engineering measures, but they typically require more resources to ensure stability and mitigate environmental risks.

SOIL TYPE (18%)

Soil type is a crucial factor in landfill site selection, as it plays a significant role in controlling leachate movement and protecting groundwater resources. Soils with low permeability, such as clay, were ranked the highest for landfill suitability because they act as a natural barrier, effectively minimizing the seepage of leachate into the surrounding environment. Clay soils can significantly reduce the risk of groundwater contamination by slowing down the infiltration of harmful substances and providing an additional layer of protection beneath engineered landfill liners. Conversely, highly permeable soils, such as sandy or gravelly soils, were deemed unsuitable due to their inability to retain leachate. These soils allow rapid infiltration, increasing the risk of leachate reaching and contaminating groundwater sources, which can have serious environmental and public health implications. Moderate permeability soils may require extensive engineering interventions, such as the addition of synthetic liners or leachate collection systems, to ensure adequate protection. Therefore, prioritizing low-permeability soils is essential for creating a landfill that is both environmentally secure and cost-effective.

LAND USE (20%)

Land use is a pivotal criterion in landfill site selection as it determines the potential environmental, social, and economic impacts of development. Vacant land received the highest suitability ranking (score 10) because it is readily available for development with minimal conflicts or displacement of existing land use activities. Utilizing vacant land ensures a smoother approval process, reduces costs associated with land acquisition, and minimizes negative impacts on the surrounding environment or local communities. Agricultural land was considered moderately suitable (score 6) due to its significant value for food production and the economic livelihoods it supports. While it may be used as a last resort, prioritizing agricultural land for landfill development could result in a loss of fertile soil and reduced agricultural productivity, necessitating careful consideration of trade-offs. Forested areas were assigned a low suitability score (score 3) because of the critical ecological functions they provide, such as carbon sequestration, biodiversity conservation, and protection against soil erosion. Developing landfills in forested areas could lead to habitat destruction, disruption of ecosystems, and public resistance due to environmental conservation concerns. Ultimately, prioritizing the use of vacant land while preserving productive and ecologically sensitive areas aligns with sustainable waste management and land use planning principles.

PROXIMITY TO WATER BODIES (20%)

Proximity to water bodies is a critical factor in landfill site selection due to the potential risks of water pollution from leachate. Areas farther from water bodies were deemed more suitable as they significantly reduce the likelihood of contaminating surface and groundwater resources. Greater distances provide a natural buffer zone, minimizing the risk of leachate infiltration into water systems even in the event of a containment failure. This is particularly important for protecting aquatic ecosystems, maintaining water quality, and safeguarding drinking water sources for nearby communities. In contrast, areas within 500 meters of water bodies were classified as unsuitable due to the heightened risk of leachate leakage and runoff directly impacting these sensitive environments. The closer proximity increases the chances of pollutants entering rivers, lakes, or groundwater aquifers, leading to long-term environmental degradation and public health hazards. Moreover, siting landfills near water bodies may contravene environmental regulations and lead to public opposition. Ensuring a sufficient distance from water bodies aligns with sustainable waste management practices and helps maintain the ecological and hydrological integrity of the surrounding area.

PROXIMITY TO RESIDENTIAL AREA (20%)

To minimize potential adverse impacts on human health and reduce nuisance effects, proximity to residential areas is a critical factor in site suitability assessment. Sites situated more than 2000 meters from residential zones are considered the most suitable, as they significantly mitigate the risk of air, noise, and light pollution, which can negatively affect nearby populations. These sites also reduce the likelihood of disturbing daily human activities, promoting a safer and more comfortable living environment for residents. On the other hand, sites within 500 meters from residential areas are deemed unsuitable due to the increased potential for nuisance impacts, such as odors, noise, and visual disturbances, which can adversely affect residents' quality of life. These sites are also at a higher risk of exposing local communities to harmful emissions or accidents, particularly if the development involves industrial processes or activities that produce pollutants. To strike a balance between the need for development and the protection of residential well-being, a buffer zone of 500 meters to 2000 meters is considered optimal for balancing these concerns. Sites within this range may still be viable, depending on specific local factors such as topography, existing infrastructure, and environmental safeguards. However, appropriate mitigation measures must be put in place to further minimize risks to nearby populations.

PROXIMITY TO ROADS (6%)

The proximity to existing road networks plays a significant role in determining site accessibility and logistical feasibility. Locations situated between 1000 and 2000 meters from roads are considered favorable because they offer a balance between accessibility and minimizing infrastructure costs. Being within this distance ensures that the site is easily reachable for transportation of materials, workforce, and goods, which is crucial for operational efficiency. Sites within 1000 meters of roads provide even greater accessibility but may also come with higher development costs due to the potential need for road upgrades, increased traffic management, and enhanced infrastructure to handle the added demand. Conversely, sites farther than 2000 meters from roads may face challenges related to accessibility, leading to higher transportation and logistical costs and potentially limiting the site’s attractiveness for development. By selecting locations within the 1000 to 2000-meter range, the goal is to ensure that transportation routes are sufficiently close to reduce costs associated with the construction of new access roads or transportation infrastructure. This also minimizes the environmental impact of road development, such as habitat disruption or increased emissions from longer transport distances. Furthermore, this range allows for better integration with existing road networks, promoting efficiency in the movement of goods, services, and personnel. The 6% weight assigned to proximity to roads reflects its importance in ensuring the practical viability of a site. It ensures that the site remains accessible without requiring significant additional investment in infrastructure, helping to keep project costs reasonable while also promoting sustainability and operational efficiency.

THE SUITABILITY MAP

The suitability map for landfill placement in the Selangor River Basin visually represents the spatial distribution of areas based on a comprehensive evaluation of multiple factors, guiding the identification of locations most appropriate for landfill development. The map categorizes areas into four distinct suitability classes, each reflecting the degree to which specific criteria are met and the potential risks or benefits associated with each location.

1. Unsuitable (Grey): Areas classified as "Unsuitable" are those that fail to meet essential criteria for landfill placement, posing significant risks to both the environment and public health. These regions may include areas with high environmental sensitivity, such as those near water bodies, wetlands, or protected ecosystems. They may also include sites with steep slopes that are prone to erosion, making it difficult to properly contain waste and prevent leachate contamination. Additionally, areas too close to residential zones, critical infrastructure, or other sensitive areas are deemed unsuitable due to the potential for adverse impacts on human health and safety.

2. Less Suitable (Yellow): "Less Suitable" areas partially meet the necessary criteria but come with some constraints that reduce their overall viability for landfill development. These locations may feature moderate slopes, which could complicate waste containment and increase the potential for runoff or instability over time. While these sites may not pose immediate risks to the environment, their proximity to sensitive areas (such as agricultural land or residential zones) can still present challenges. Proper mitigation measures would be needed to minimize the risks associated with these sites, such as controlling waste seepage and managing traffic or odor issues.

3. Suitable (Blue): "Suitable" regions meet most of the criteria for landfill placement, offering favorable conditions for development. These sites typically have gentle slopes, sufficient distance from sensitive zones, and a manageable environmental impact, making them viable for landfill operations. However, these areas may present some minor limitations, such as the need for additional infrastructure development or environmental monitoring to ensure long-term sustainability. Though these areas are generally considered favorable for landfill placement, further detailed assessments and precautions may still be necessary to mitigate any residual risks.

4. Most Suitable (Red): "Most Suitable" areas represent the optimal locations for landfill placement, based on the comprehensive evaluation of all relevant factors. These sites meet the strictest criteria, demonstrating ideal conditions for safe, efficient, and environmentally responsible landfill operations. They are located away from sensitive environmental zones, have minimal slope, and are sufficiently distanced from residential and commercial areas to avoid health and safety risks. These sites are considered the best candidates for landfill development, requiring minimal mitigation efforts to meet the highest standards of waste management and environmental protection.

By categorizing these locations, the map helps decision-makers prioritize areas that strike the best balance between waste disposal needs and the preservation of natural resources and human health. It provides an essential tool for planning and managing landfill operations, guiding the selection of sites that will have the least adverse impact while accommodating necessary waste disposal activities.

CONCLUSION

In conclusion, this project presents a thorough and data-driven suitability assessment for landfill placement within the Selangor River Basin, employing multiple evaluation criteria to identify the most appropriate sites for development. The use of a suitability map, categorizing areas into four distinct classes, allows for a clear visualization of regions that meet the necessary requirements for safe and efficient landfill operations. By considering factors such as environmental sensitivity, proximity to residential zones, slope stability, and infrastructure access, the assessment ensures that landfill sites are selected with careful consideration of both ecological preservation and human health protection. The findings from this project provide crucial insights for decision-makers, helping to prioritize areas that minimize environmental risks, reduce logistical costs, and ensure the long-term sustainability of waste management practices. The identification of the most suitable and least suitable locations, alongside the recognition of potential constraints and mitigations, contributes to more informed and strategic urban planning. Ultimately, the project fosters responsible landfill development that supports sustainable waste management while safeguarding the environment and local communities for future generations.