Channel morphology of the Indus, and the growing risk of floods related damages in the Indus River basin

The Indus River is the mainstay of Pakistan’s agricultural economy and water supply. It supports the longest stretches of its natural fauna and flora. It has been subjected to massive changes because of the Indus Water Treaty of 1960, which led to a partitioning of water rights between India and Pakistan, the construction of dams and barrages along the rivers in Kashmir and Pakistan, and in the last few decades, occupation of its active floodplain for agriculture. This later led to the development of small towns and villages right in the middle of the dried-out river bars. We provide a systematic analysis of the evolving stream morphology using remote sensing data, in mapping each year’s pre-monsoon period from 2000 to 2023 and leading to an analysis of the impact of high flow on the river every monsoon. We used Moderate Resolution Imaging Spectroradiometer (MODIS) 250 m data to map the flood water retention by floodplains and cover plains of the Indus basin. We found that the floodplain remained inundated for up to ~ 60–85 days at a stretch, after the monsoon. The Indus River was the most affected, registering an average of ~ 1,548.81 m of channel width changes, ~ 864.81 m for Jhelum, ~ 661.50 m for Chenab, and ~ 335.80 m for Sutlej as the flow intensity of water gradually declines toward the eastern streams. In contrast, the Ravi River was impossible to map from satellite images, due to its year-round low flow. Similarly, the braid index was ~ 5.03, ~ 6.86, ~ 4.73, and ~ 0.79, respectively while the sinuosity index was ~ 1.27, ~ 1.22, ~ 1.20, and ~ 1.34. We also calculated the loss of cultivated land in the river floodplains, these are regularly cultivated despite floods and continue to increase vulnerability. A total of ~ 2260.61 km2 of cultivated land was eroded by the Indus from 2000 to 2023, and ~ 596.87 km2, ~ 712.09 km2, and ~ 518.42 km2 along Jhelum, Chenab, and Sutlej River in Punjab, respectively. Several districts of Khyber Pakhtunkhwa and Sindh remained inundated for up to ~ 700 days in the 20 years period studied. Although, Punjab benefits from raised lands between rivers (popularly known as “Doabs” between two rivers), the alluvial plains of Khyber Pakhtunkhwa and cover floodplains of Sindh allows for recurring inundation and damages.