River of ice

Lambert - Fisher Glacier, Antarctica. Image from Google earth

 

 

Glacier is a moving mass of ice. It is different to iceberg in that, it moves over land and is much larger in size. The term “glacier” is from the French word ‘glace’, which has been taken from latin word ‘glacies’, both meaning ice.

Glaciers are formed due to snow fall and accumulation of ice over longer periods of time. With increasing snowfall, ice accumulates in glaciers. This leads to two different processes in a glacier formation. First is the process of compression within the glacier. It makes the glacier much denser and heavier. Secondly, increased weight of the glacier makes it move downwards, towards a lower area.

While moving down, glaciers erode and deposit, thus creating many features. Antarctica, Greenland, Alaska, Himalayas are some of the regions with glaciated landscapes.

Why are glaciers relevant?

Though, the relevance of a glacier may be mainly as a vacation spot for people not living in its vicinity. Glaciers are much more than that. It is relevant to human life economically, environmentally as well as socially.

It is very difficult to assess the tangible economic value of a glacier for a nation or state. But it a priceless resource with immense direct and indirect values. Its importance can be analysed from a 2014 report by U.S. Geological Survey economists Catherine Cullinane Thomas and Christopher Huber and National Park Service economist Lynne Koontz. The report is about the economic gains from Glacier national park in 2014. The report shows the one year benefits received from the glacier park to the economy, in form of income and the employment generated in the area. This study is not only the single example of the economic relevance of a glacier. In reality, there are immense benefits and gains which are still not explored.

Environmentally, glaciers provide nutrients to soils, rivers, lakes and oceans. They are a great source of fresh water and has an important role in maintaining the water balance in climate. They are also important in maintaining the salinity level of the oceans. Infact, if we realise, glaciers are a relevant part of the whole environmental balance of nature. A minor change in this natural equilibrium may disrupt the whole system.

Khumbu Glacier- Highest glacier in the world. Image from Google Earth

 

Glaciers are relevant socially as well as culturally. They are sites of powerful sacred and symbolic meanings for local communities (Allison 2015). A study by Allison (2015) shows the spiritual connection of the communities in the Peruvian Andes, the Nepalese Himalaya, and the Meili Snow Mountains of Yunnan, China to the glaciers. Glaciers are source of many important rivers which are considered sacred by its masses.

Some Facts about Glaciers -

Largest glacier in the world - Lambert-Fisher Glacier in Antarctica, 400 km long, and up to 100 km wide.

Highest glacier in the world - The Khumbu glacier in north-eastern Nepal. Its elevation is 4,900 m at its terminus to 7,600 m at its source.

Oldest glacier – The oldest glaciers ice can be found in Antarctica which is about 1,000,000 years old. In Greenland it is more than 100,000 years old.

References –

Allison, Elizabeth. (2015). The spiritual significance of glaciers in an age of climate change. Wiley Interdisciplinary Reviews: Climate Change. 6. 10.1002/wcc.354.

Decoding the satellite image - Baitarni Estuary, India.

LISS III image Baitarni Estuary, Odisha

The LISS III satellite image is acquired from Bhuvan portal by National Remote Sensing Centre, ISRO, Government of India, Hyderabad, India.

Decoding the Satellite image -

Google Earth Image of Baitarni Estuary, Odisha

The LISS III image is taken on February 2018. As you can see, it is not a natural colour image. A natural colour image of the same region will not have much brighter colours, like the Google Earth image given here. The hues of the features have the same shades as it is present in the nature. However, it is somewhat difficult to distinguish the features as all the colours merge into each other.

The colourful image i.e. the LISS III satellite image is a false colour composite (FCC). The regular RGB bands are not used in a FCC image, instead other band images are taken. In the FCC image here Red, Green and Infra-red band has been used. The FCC image highlights the features with bright shades which reveal lots of information. LISS III is a multi-spectral sensor employed in ISRO's Resourcesat satellites which capture images in visible and infra-red bands.

In this LISS III image, many distinguishable features in bright shades are visible. One can easily distinguish between the triangular landmass and surrounding water feature in the region by the tone and texture of the features. Another distinguishable feature here is the curvy, meandering bright blue Baitarni river dissecting the landmass. The dissimilar shades of blue in different section is due to presence of suspended particles and sediment brought by the river. As it falls into the Bay of Bengal, the extent of the suspended sediments is clearly visible in different shades of the sea.

Kanika sand island is visible in the Bay of Bengal as bright red patch, east of the main landmass. It is a densely vegetated mangrove forest confirmed by the bright red shade in the FCC. In the mainland, two major and many minor bright red patches are also discernible. The patches are in dissimilar shade/tone of red owing to type, health, and density of vegetation in the region. The two major patches are forested part of the Bhitarkanika national park and wildlife sanctuary. In the northern part of the mainland, cyan/turquiose toned small sized specks of land along the river are the settlements.