Monsoonal flooding in South
Asia: a frequent and dangerous peril

The South Asian countries of India, Nepal and Bangladesh experienced extensive flooding in July 2019, coinciding with the two-year anniversary of the deadly 2017 monsoonal flooding that affected 41 million people across the region.

Monsoonal flooding in the region

The South Asian monsoon affects the Indian subcontinent, including Bangladesh and Nepal. It can be sub-categorised into the south-west monsoon (SWM) and the north-east monsoon (NEM). The SWM occurs over the Indian subcontinent and neighbouring countries, with most of the rainfall concentrated between the months of June and September.

Monsoon rains are important for the survival of agricultural industry in the region. For example, the seasonal rainfall is responsible for irrigating at least 55% of India’s cultivated land. Output from agricultural farms accounts for 15% of India’s USD $2.5 trillion economy (Jadhav, 2019).

The 2019 flooding

Although the annual monsoon season started off dry in some states of India, with rainfall below average resulting in a shortage of water for crops, some locations in India, Nepal and Bangladesh received up to 613mm of rainfall between 11 and 21 July 2019 (Reuters, 2019b; NASA PPM, 2019) (Figure 1).

Figure 1: Rainfall accumulation (mm) in Bangladesh, India and Nepal from 11-21 July 2019, based on daily precipitation data collected by NASA Precipitation Measurement Mission. (Data source: NASA PPM, 2019). The darkest blue represents maximum rainfall of 613mm. JBA recognises that various international boundaries, territories, names and the designation of such are the subject of contest and dispute. Their representation on this map is solely for the illustration of natural perils and does not imply any recognition or endorsement of any such contested or disputed issues.

The worst affected areas in India were the states of Uttar Pradesh, Bihar and Assam, with 30 out of 33 districts flooded in Assam (Choudary, 2019). Between 11 and 17 July 2019, Assam received an estimated 175.3mm of rainfall (76% more than normal) while Bihar received a total of 170.3mm over the same week (88% more than normal) (India Meteorological Department, 2019a). Figure 2 illustrates the flood extents of a section of the Brahmaputra River in southern Kamrup district, Assam.

Figure 2: Left: JBA’s 1-in-20-year India 30m river flood map showing the Brahmaputra river in southern Kamrup district, Assam, India (JBA Risk Management Limited). Right: Extent of flooding, shown in dark blue, observed from satellite data as captured on the 15 July 2019. In orange, satellite imagery captured on 28 March 2019. (Data source: NASA, Sentinel-2).

One week after the floods in Assam and Bihar, the India Meteorological Department (IMD) predicted 200mm of rainfall in 24 hours for the Kozhikode, Wayanad and Kannur districts of Kerala (Nidheesh, 2019). Following the floods in Kerala in 2018, authorities have learnt the lesson of dam management and, prior to the arrival of the heavy rainfall as predicted by IMD, five dams were ordered to open in Kerala (Nidheesh, 2019).

Heavy rainfall extended to the neighbouring countries of Nepal and Bangladesh as well (Paul and Quadir, 2019). The floods killed at least 400 people and affected more than 10 million people in all three countries combined (Channel News Asia, 2019).

In the shadow of Hurricane Harvey: the unprecedented 2017 South Asian floods

The 2019 flooding experienced in India, Nepal and Bangladesh coincided with the anniversary of the 2017 flooding in the same region. The 2017 floods were widely regarded as unprecedented, with widespread monsoon rainfall generating some of the most severe flooding seen in over a decade, despite being overshadowed in the media by Hurricane Harvey.

However, many reports indicate that rainfall was only 95% of the long period average. So, what made the 2017 South Asian floods unprecedented?

Figure 3: The number of people affected (millions) by the 2017 monsoon flooding in the region, as of 1 September 2017. (Data sources: OCHA (2017), DeLorme (2012)).

Tracking the 2017 South Asian monsoon – a snapshot of events as they unfolded

The 2017 South Asian monsoon was predicted to be an average monsoon season, yet the latter half of the season saw unexpected devastation in the India-Bangladesh-Nepal border region (Solace Global, 2018). Reports state that almost 2,700 people lost their lives as a result of the monsoon, with more than 41 million affected by the event between the start of June and October (The Guardian, 2017a; Munich Re, 2018) (Figure 3).

In 2017, the SWM began around 13-14 May in the Bay of Bengal and by the end of the month had reached Kerala, in southern India, and Sri Lanka (IMD, 2017; WSWS, 2017). Between late June and early July, Assam, in eastern India, was badly hit. Average July rainfall in the district of Lakhimpur was recorded at 931.5 mm (Figure 4), over 60% greater than the July monthly average for the previous three years (IMD, 2019b).

Figure 4: Monthly average rainfall for the district of Lakhimpur in Assam, India. Rainfall in 2017 was higher in the district than adjacent years, contributing to widespread flooding and displacement of thousands of people. (Data source: India Meteorological Department).

During August, the SWM caused high totals of rainfall in higher latitude areas, including the Indian states of Sub-Himalayan West Bengal and Sikkim, as well as across Nepal, which caused flood waters to wash down major river systems. This resulted in the flooding of further lowland areas in Nepal, northern Bangladesh and the Indian state of Bihar (Figure 5).

Figure 5: Average monthly rainfall (mm) across the region, highlighting the spatial and temporal distribution of the monsoon rains in 2017. Indian central states received their highest monthly rainfall total in July. Even greater monthly rainfall totals occurred at higher altitudes later in August across the Indian states of Sub-Himalayan West Bengal and Sikkim and across Nepal. High rainfall in these three regions in August contributed to widespread flooding in the state of Bihar, India, and northern Bangladesh. (Data source: Government of Nepal (2019) and (2019)).

Nepal was struck by what was described by the United Nations as the worst rains in 15 years; in Terai, 150 people lost their lives and around 90,000 homes were destroyed (Independent, 2017). Meanwhile, some of the hardest hit areas in Bangladesh were the Bogra and Jamalpur districts that are situated either side of the Brahmaputra River in north-west Bangladesh (Figure 6). Here, over 1.18 million people were affected by floodwaters, with 41.11% of the population in Jamalpur affected (Nirapad, 2017).

Figure 6: An extract of JBA’s 1-in-100-year fluvial flood map showing areas at risk of flooding in the region. In 2017, Bihar in north-east India and the Bangladesh districts of Bogra and Jamalpur were particularly affected.

The significance of the 2017 monsoon

Although monsoons and subsequent flooding are an annual phenomenon, the 2017 monsoon was particularly significant due to the temporal extent of the event, despite reports indicating that rainfall was only 95% of the long period average across the region (IMD, 2017).

Whilst the typical SWM season runs from June to September, in 2017 the SWM season ran between April and October for Bangladesh, India and Nepal. This was particularly evidenced by the Meghna basin of Bangladesh, with flooding affecting 125,885 hectares of crop lands in early April (Floodlist, 2017b). Rainfall from the SWM then continued with a number of record-breaking events in quick succession, compared with the usual one or two events (Akanda et al., 2017).

What was the impact?

The 2017 monsoon had one of the highest number of fatalities from natural disaster that year (Munich Re, 2018). However, despite this, the insured losses of the 2017 monsoon only totalled a comparatively low USD $3.5 billion between India, Nepal and Bangladesh: USD $2.5 billion from India, USD $600 million from Nepal and USD $350 million from Bangladesh (Munich Re, 2018). In comparison, Hurricane Harvey, which occurred between 17 August and 2 September 2017, resulted in a total economic loss of USD $85 billion (Swiss Re, 2018).

This highlights the significant protection gap present in South Asia. Only 8% of losses in South Asia were insured during 2017, thus the true economic cost of damages can be difficult to calculate (Insurance Business, 2018). This is often reflected when comparing disaster events in South Asia with other disasters from around the world, with losses often one or two orders of magnitude smaller in South Asia than that seen in Europe or North America (Munich Re, 2018).

Despite this, the social impacts are usually far greater in developing countries. Again, when compared to Hurricane Harvey, 13 million people were affected across Texas (particularly Houston) and Louisiana, whereas the South Asian floods in 2017 affected 41 million (Ferreras, 2017).

Looking to the future: insurance take-up in the region and effects of climate change

The social and economic impacts of flooding could be reduced through improved take-up of insurance across South Asia to reduce the protection gap. However, having affordable and reliable insurance policies for flooding in Bangladesh, India and Nepal has proven difficult due to how prone these areas are to flood. Traditionally, insurance policies available are too expensive or inefficient, resulting in low demand for cover and a poor understanding of insurance (Cole et al., 2013).

This poses a challenge as, by the 2070s, India and Bangladesh are projected to have 14% of all global assets that are exposed to flood risk, with issues like climate change and urbanisation exacerbating Asia’s flood exposure (Geneva Association, 2015). For example, it’s believed that climate change may increase monsoonal flooding due to warmer land and ocean surface temperatures and subsequent increases in the amount of moisture in the atmosphere, two driving forces of a “wetter” monsoon (Amirith, 2018).

The impact of flooding is therefore far greater within these developing countries where the protection gap is high, despite some moves towards more sustainable housing construction to withstand large-scale flood events, including building houses on stilts and using reinforced concrete walls (Rajendran, 2019).


JBA Risk Management has nationwide return period flood maps and probabilistic flood modelling at 30m resolution for South Asia. We also offer an India Crop Model which captures multiple extreme weather perils contributing to seasonal crop failure, including flood and tropical cyclone damage. This data can help organisations understand, manage and mitigate flood risk in the region.

If you are interested in any of our products or services, please get in touch for more information.


Akanda, A., Palash, W., Hasan, M. and Nusrat, F. 2017. Understanding the Unusual 2017 Monsoon and Floods in South Asia. AGU FAll Meeting Abstracts. [online] Available at: [Accessed 8 Jul. 2019].

Amrith, S. 2018. Unruly Waters: How Mountain Rivers and Monsoons Have Shaped South Asia’s History. London: Allen Lane.

Channel News Asia. 2019. Monsoon toll tops 650 as rains unleash flood fury in South Asia. [online] Available at: [Accessed 30 Jul. 2019].

Choudhary, S. 2019. Floods ravage north-east India & Bihar, IMD declares red color warning for Assam. Livemint. [online] Available at: [Accessed 30 Jul. 2019].

Cole, S., Gine, X., Stein, D., Tabacman, J., Topalova, P., Townsend, R. and Vickery, J. 2013. Demand for Rainfall Insurance in India. [online] Abdul Latif Jameel Poverty Action Lab. Available at: [Accessed 8 Jul. 2019].

FAO. 2017. GIEWS Update - Bangladesh. [online] Available at: [Accessed 8 Jul. 2019].

Ferreras, J. 2017. Hurricane Harvey has affected 13 million, South Asian floods have affected 41 million. [online] Global News. Available at: [Accessed 8 Jul. 2019].

FloodList. 2017a. Updated: India – 150 Villages Affected as Flooding Continues in Assam. [online] Available at: [Accessed 8 Jul. 2019].

FloodList. 2017b. Bangladesh – Floods in North East Wipe Out Rice Crops. [online] Available at: [Accessed 8 Jul. 2019].

Geneva Association. 2015. Insuring Flood Risk in Asia’s High-Growth Markets. [online] Zurich: The Geneva Association. Available at: [Accessed 8 Jul. 2019].

The Guardian. 2017a. While the world's attention is elsewhere, Bangladesh faces a humanitarian crisis. [online] Available at: [Accessed 8 Jul. 2019].

The Guardian. 2017b. Floods and devastation in India, Nepal and Bangladesh – in pictures. [online] Available at: [Accessed 9 Jul. 2019].

The Independent. 2017. Floods in India, Bangladesh and Nepal kill 1,200 and leave millions homeless. [online] Available at: [Accessed 8 Jul. 2019].

India Meteorological Department. 2017. 2017 Southwest Monsoon End of Season Report. [online] Available at: [Accessed 8 Jul. 2019].

India Meteorological Department. 2019a. Customized Rainfall Information System. [online] Available at: [Accessed 8 Jul. 2019].

India Meteorological Department. 2019b. Monsoon. [online] Available at: [Accessed 8 Jul. 2019].

Insurance Business. 2018. A new normal: Natural disaster numbers hit historic highs. [online] Available at: [Accessed 8 Jul. 2019].

Jadhav, R. 2019. India to get above-average monsoon rains in next two weeks. Reuters. [online] Available at: [Accessed 30 Jul. 2019].

Munich Re. 2018. Asian floods overshadowed by Houston flooding [online] Available at: [Accessed 8 Jul. 2019].

NASA Earth Observatory. 2017. Severe Monsoon Rains Flood South Asia. [online] Available at: [Accessed 8 Jul. 2019].

NASA PPM. 2019. NASA Precipitation Measurement Missions. [online] Available at: [Accessed 30 Jul. 2019].

Nidheesh, M. 2019. Four killed as heavy rains batter Kerala, state opens 5 dams. Livemint. [online] Available at: [Accessed 30 Jul. 2019].

Nirapad. 2017. Flood Situation Updated on August 22, 2017. [online] Available at: [Accessed 9 Jul. 2019].

Paul, R. and Quadir, S. 2019. More than 60 killed, hundreds of thousands displaced by flooding in Bangladesh. Reuters. [online] Available at: [Accessed 30 Jul. 2019].

Rajendran, K. 2019. Flood-resistant housing attracts attention in Kerala. [online] Available at: [Accessed 30 Jul. 2019].

Reuters. 2019. Crop planting slows in India on weak monsoon rains. [online] Available at: [Accessed 30 Jul. 2019].

Solace Global. 2018. 2018 South Asia Monsoon Season. [online] Available at: [Accessed 8 Jul. 2019].

Swiss Re. 2018. At USD 144 billion, global insured losses from disaster events in 2017 were the highest ever, sigma study says. [online] Available at: [Accessed 8 Jul. 2019].

The Times of India. 2017. Monsoon in India: Rain fury in several states, Assam flood situation grim. [online] Available at: [Accessed 8 Jul. 2019].

World Food Programme. 2017. Nepal Terai flood August 2017. [online] Available at: [Accessed 8 Jul. 2019].

WSWS. 2017. Over 200 killed in Sri Lankan floods, now cyclone hits Bangladesh. [online] Available at: [Accessed 8 Jul. 2019].