I do not necessarily devote time to writing articles on the effects of urbanization on ecology because it would take a lot of painstaking research and consume a lot of time without any prospect of attracting the attention of the concerned authorities who bear the responsibility of sustaining the environment. Scores of research papers have been written on the topic with no effect. But a Prime Time report aired on NDTV on 20th June 2019 about the water crisis last year got me thinking. The report is available on youtube. In that report, anchor Ravish Kumar alleges that in Bihar water reservoirs and public ponds are being taken over by land-mafias for illegal construction. Now, 'illegal' in this case might be considered a relative term since Ravish Kumar reports that proper documentation of those wetlands and ponds are being altered in government land registry offices by the land-mafia (obviously working in cahoots with the local political system) to remove any evidence of a wetland being present at the site of the development project and thus the property is legally acquired by the land-mafia. Hence, if some concerned citizen files a PIL (Public Interest Litigation) against the 'developers' or 'promoters', it is virtually impossible to prove a pond being present at the site prior to the construction (as the records have been altered). 

But there are some records which are out-of-reach of the land-mafias (and one may use them to prove the effect urbanization has on ecology) unless the government decides to totally censor the internet. These records are the satellite imageries available on Google Earth and can be used for various GIS (Geographic Information System) studies.

It is relatively easy to use google earth and once you become fluent in its operation, you can feel like an online sleuth - analyzing information to point out illegal wetland fillings and ecosystem destruction.

Now, how do you start? First, you download the Google Earth Pro installer on your machine. 

Once you do, follow the instructions and install the software on your machine. 

After completing the installation, launch the software.

After launching the application, type your place of interest (the satellite imagery of the place you want to see) in the 'search' bar. 

But, to prove the existence of geological feature which no longer exists (in Bihar's case - wetlands) you have to search for historical satellite imagery in the application.

It will give you access to historical imagery. 

A slider will appear (marked within red circle) where dates are noted. You have to slide the peg on the slider with your mouse to search for historical imagery as it appeared on your desired date. 

The satellite imagery depicted here is from Burdwan, a small municipal town in West Bengal, India and we will use imagery from Burdwan for our case study. 

You can see the date in the current imagery is noted at the bottom (marked by a red circle) at 3/29/2020 in the MM/DD/YYYY format.

The imagery depicts the eastern shore of the river Damodar which runs adjacent to Burdwan town. The eastern shore of the river seems to be some kind of agricultural land and some other structures. We will use the canal running parallelly with the river (the black line in the upper right corner) as our reference point to understand changes in the geographical features due to human activity.

This image depicts the same location from October 2001 (notice the date encircled in red). 

As you see in the imagery from this year (March 2020), the distance from the canal to the eastern shore is roughly 800 metres. 

The imagery from 2001 of the same spot illustrates that the eastern shore was much nearer to the canal (at least a third of the present distance of 800 metres) hence implying that the current land was claimed from the river thus degrading the navigability and the water carrying capacity of the river. 

This has been the current trend for the last two decades. Land for urbanization has been claimed from wetlands and other environmentally sensitive areas.

The above two images (the first one from 2001 and the second one from 2020) shows a pond in Burdwan known as Dhal Dighi. The width of the pond in 2001 was roughly 86 metres. Whereas the imagery form 2020 clearly shows that the width has diminished due to the land being claimed from the pond for construction of buildings (probably apartment blocks). 

These two images (the first from 2001 and the second from 2020) shows a portion of G.T Road on the outskirts of Burdwan. The place has become almost unrecognizable in 2020 with the construction of a new bus terminal and adjacent apartment complexes. As we can clearly distinguish from the above two images that urbanization has caused the loss of green cover (trees), agricultural land and waterbodies.

Even protected ecological areas are losing green cover as it is evident from the above two images showing the Ramnabagan Wildlife Sanctuary of Burdwan. From 2001 to 2020, the sanctuary has lost considerable green cover, with man-made structures clearly visible in the image from 2020 which were not there in 2001.

The issue is more pronounced in metropolitan areas.

In the above two images, we can see the 'Captain Bherry' which is a part of the East Kolkata Wetlands, a protected wetland under the Ramsar Convention. In the image from 2020 (2nd image) we can see urban construction right through the middle of the Captain Bherry. It is probably the under construction East-West route of the Kolkata Metro. The East Kolkata Wetlands are often called the kidneys of Kolkata and hosts a highly diverse flora and fauna. People living around the wetlands mainly depend on them for their livelihood. The East Kolkata Wetlands supports a large number of families through pisciculture. Destruction of the wetlands would lead to a loss of livelihood for a large community of people. So, depredation of the wetlands would not only cause ecological imbalance but economical deprivation as well. 

Google Earth's feature to view historical satellite imagery is a fascinating tool to study geographical changes over time. It clearly shows the consequences of unplanned and unsustainable urban development on the environment and on human life in the long term. But most importantly, it serves as a digital proof of land features thus ensuring that even when government records are altered, Google Earth can serve as a backup tool for the concerned citizen.