Dumpsites are a major urban challenge, contributing to air pollution, water contamination and various health hazards. Yet most cities in India continue to struggle with managing them. Delhi, for instance, is home to three major dumpsites—Ghazipur, Okhla, and Bhalswa—which have become environmental time bombs. These landfills release toxic gases into the air and contaminate groundwater through harmful leachates, exposing nearby communities to a wide range of health risks.
Despite the growing concerns, most cities still lack an accurate understanding of the size and waste burden of their dumpsites. Delhi alone generates about 11,000 tonnes of solid waste daily, a figure that excludes waste generated by the city’s floating population. The bulk of this waste ends up in these three overflowing dumps, making it difficult for authorities to manage or remediate it effectively. Efforts by municipal authorities, including bioremediation, biomining and waste-to-energy plants, are simply not enough to tackle the sheer volume of this waste.
Currently, most cities rely on manual estimation to understand the quantum of waste in the dumpsites. The process is lengthy, costly and in certain cases also not accurate, derailing the planning process. Instead, cities can use satellite imagery and Geographic Information System (GIS) technologies to efficiently quantify and monitor dumpsites. Satellite imagery makes the entire process of waste quantification quicker and cheap. Moreover, it provides a comprehensive view of changes in waste volume and surface conditions over time, making it easier to track the progression of these dumps.
Using satellite imagery, we tried to ascertain demarcation of the three dumpsites in Delhi, quantify their waste volume and study the change in their mean land surface temperature (LST) over time. LST, which tends to increase with higher waste levels, was utilised as a key indicator to track waste volume changes and validate our findings.
Our study spanned a decade (2013-24) and relied on satellite imagery from the US Geological Survey’s Landsat missions, specifically Landsat 5 and Landsat 9. These images were processed using QGIS to identify the dumpsites with coordinates (latitude and longitude) and superimpose them on composite satellite images to observe significant changes. LST was calculated using scientifically validated algorithms. To estimate dump volumes and areas, we employed a Digital Elevation Model from US space agency NASA’s Shuttle Radar Topographic Mission for 2013, and India’s IRS-Cartosat satellite data for 2024.
Heaps of trouble
Results from our study reveals significant changes at the Bhalswa, Ghazipur, and Okhla dumpsites over the past decade. While the overall area of the dumpsites remained unchanged, the amount of waste they contain has more than doubled.
The Bhalswa dumpsite, covering 29.36 hectares (ha), saw an 88 per cent increase in waste, rising from 1.59 million tonnes (MT) in 2013 to 2.94 MT in 2024. Despite being the largest in size, Bhalswa’s waste burden is still outpaced by Ghazipur, which spans 28.72 ha. Ghazipur’s waste almost tripled in 10 years, reaching 3.34 MT in 2024—the highest among the three. The Okhla dumpsite, although smaller at 16.71 ha, experienced a 52 per cent rise in waste volume, going from 1.52 MT in 2013 to 2.31 MT in 2024.
In addition to the rising waste volumes, there has been a notable increase in mean LSTs at all three sites, a clear sign of escalating environmental pressure. Bhalswa recorded the sharpest temperature rise, from 31.39°C in 2013 to 35.89°C in 2024. Okhla’s mean LST jumped to 35.4°C in 2024 from 32.1°C, while Ghazipur saw an increase of nearly 2°C, reaching 34.11°C in 2024. The high temperatures indicate that much of the waste being dumped is organic, which generates significant heat as it decomposes.
We also generated 3D models of the dumpsites to visualise how their shapes have changed over time. Both Bhalswa and Ghazipur have transitioned from having multiple peaks in 2013 to a single peak in 2024, likely because of ongoing bioremediation efforts. Despite the reclamation initiatives, the waste burden continues to outpace efforts to reduce it, highlighting the need for more effective management strategies.
