Bangladesh Physiography

Bangladesh Physiography

Meghna in Borisal

Meghna in Borisal

The Bangladeshi part of the Joint River Commission in Bangladesh has over 400 rivers in total. These include 54 rivers that flow mostly from India to Bangladesh and three rivers that come from Myanmar. The rivers Ganges / Padma and Brahmaputra / Yamuna are counted among the ten largest rivers on earth, measured by the average water volume at the lower reaches of the respective river. Ganges / Padma is mostly classified as the fourth largest, Brahmaputra / Yamuna as the ninth largest river.

The climate in which Bangladesh is located also contributes to the size of these rivers. As a country located in southern Asia according to usaers, Bangladesh is in the northern tropic, which means a tropical climate and monsoon (transliterated: mausumi) for the entire country. Usually from March to the end of May, known as summer or ‘heat’ (transliterated: grīṣma, grīṣmakāl) in Bangladesh, temperatures average 26-29 °C. Evaporation is greatest during summer. Thunderstorms and cyclones (transliterated: ghūrṇijhaṙ, jhaṙ) due to these climatic conditions. Cyclones are tropical cyclones that can develop high wind speeds. For example, the maximum speed of cyclone Sidr (transliterated: SiḍꞋr) was 215 km / h in 2007. They mostly affect the coastal areas of Bangladesh and neighboring countries. June to September is the rainy season (transliterated: barṣā). Precipitation, humidity and degree of cloudiness are highest during this period. Up to 80% of the annual precipitation falls during the four months at constant temperatures, an average of 30 °C. The amount of annual precipitation varies in the individual Bangladeshi areas. In the northeast of the Sylhet district (transliterated: Sileṭ), on the border with the Indian state of Meghalaya (transliterated (bengal.): Meghālaẏ), the country’s highest annual rainfall is measured at around 5,500 mm per year. In the capital Dhaka (transliterated: Ḍhākā) it is about 1,750 mm. After the rainy season, a kind of autumn follows from the end of September to mid-November. Then the temperatures are around 27 °C and the weather conditions are hot, sunny and humid. Also at this time of year cyclones can form over the Bay of Bengal and damage the coastal regions of the Gulf. The dry season after that, from December to February, is called winter or cold season (transliterated: śītꞋkāl, śīt). The temperatures are then around 15 °C.

Dry season - agriculture near Nawabganj

Dry season – agriculture near Nawabganj

The average annual temperature in Bangladesh is given as 25 °C. However, under special conditions and in certain areas, maximum temperatures of over 40 ° C or lowest temperatures of 4 °C can occur. The latter and also ground frost can form during the dry season – very rarely and exclusively on exposed relief elevations, for example in the Barind Tract (transliterated: Barendra Bhūmi) in western Bangladesh.

Winds are usually light. They blow depending on the season – before and during the rainy season, air flows in a north-westerly, northerly direction, which is reversed after the rainy season. Thunderstorms and cyclones before and after the rainy season are a few exceptions. Because cyclones occur more frequently in these periods, the casual term ‘cyclone season’ can sometimes be found for these months – in conversation with locals or in the local and international media.

Bangladesh’s land area is 147,570 km². Of this, around 9,700 km² are permanently flooded by rivers, lakes, artificially created reservoirs, baths and the like, i.e. also during the less rainy period between October and April. However, these figures vary widely. The two countries India and Myanmar are the only direct neighbors of Bangladesh. The border with India is approximately 4,142 km and that with Myanmar 271 km.

River bed erosion on the Katcha River

River bed erosion on the Katcha River

Bangladesh consists of different types of relief. The so-called Chittagong Hill Tracts (transliterated: Pārbatya Caṭṭagrām) are the only mountainous region. They are located in the southeast of Bangladesh. The highest mountain there is 1,052 m high and at the same time the highest point in the entire country. With a few exceptions, the relief in the rest of Bangladesh does not exceed 10 m above sea level. This type of landscape takes up about 80% of the country’s area and is characterized by wide plains as well as lowlands and beds of water. The majority of Bangladesh is therefore a wide alluvial plain, in which a lot of water cyclically collects through rivers and rainwater and runs wide. Seasonal, meter-high floods (transliterated: banyā) occur naturally in this delta and have also been archaeologically proven for centuries, for example. An exception to this type of landscape is the Chittagong Hill Tracts, the Barind Trakt (transliterated: Barendra Bhūmi). It is an elevation and platform of about 20-40 m above sea level, which lies in western Bangladesh on the border with India and continues in the neighboring Indian state of West Bengal (transliterated: PaścimꞋbaṅga).

Political map of the Bangladeshi districts

Political map of the Bangladeshi districts

Basic data

Apart from these articles, basic knowledge about Bangladesh can be viewed online at the Asian Development Bank and in the CIA’s World Factbook. They contain the most important information and statistical data. Other organizations that make comparable data available on their websites are the Bangladesh Bureau of Statistics, the World Bank and the United Nations database.

At Barisal

At Barisal

 

High risk from natural disasters

In the Sundarbans National Park

In the Sundarbans National Park

Mangroves supply themselves with oxygen

Mangroves supply themselves with oxygen

A high risk from natural disasters is referred to in the specialist literature using different terms. Examples are ‘disaster prone’, ‘(natural) disaster risk’, ‘high (natural) disaster risk’ or even ‘high (natural) disaster risk’. The whole of South Asia is sometimes referred to as a ‘disaster prone area’. The reasons for this include relatively frequent weather phenomena such as cyclones, heavy rain, high drought at high temperatures and others. Such climatic or weather conditions can occur not only in Bangladesh, but also in much of South Asia and endanger the lives of local residents. They are largely climatic and are promoted in extent and frequency by human influence. On the “United Nations University Institute for Environment and Human Security, most of the countries of South Asia are listed among the moderately to most vulnerable to natural disaster countries. According to this listing, Bangladesh is considered to be the most vulnerable.

City garden in Dhaka on the grounds of the Armenian Church

City garden in Dhaka on the grounds of the Armenian Church

It should be added that the Himalayan region (transliterated: Himālaẏ), northeast India and Myanmar are seismically active. Earthquakes (transliterated: bhūmikampa, bhūkampa) with epicentres in Bangladesh’s wider area can also be measured in Bangladesh. Occasionally people died in an earthquake and parts of the infrastructure were destroyed or damaged. In the past ten years there have been at least three weather events in which over 100 people have died in Bangladesh: 1. Floods in July-September 2017; 2. Landslides in Southeast Bangladesh June 2017; 3. Cyclone Aila (transliterated: Āilā) May 2009.

Fruits on the jackfruit tree

Fruits on the jackfruit tree

Most recently, in May 2020, Cyclone Amphan caused severe damage to large parts of western Bangladesh and some neighboring Indian states. In Bangladesh, this particularly affected the Bangladeshi part of the Sundarban nature reserve and other areas of the Khulna division. Authorities reported that 200,000 residents.

Test area for new breeds

Test area for new breeds

River bed erosion

River bed erosion