Anurag Kumar
A combination of unusually heavy rainfall in the upper reaches of Himachal Pradesh and Uttarakhand, leading to a heavy flow of water from the Hathinikund Barrage that regulates the flow of water into Delhi (it is not a dam, so it does not have a reservoir for storage or overflow channels), and environmental factors such as the reduced absorption capacity of the riverbed and riverbanks, and encroachment of the Yamuna floodplain have caused the unprecedented flooding. The situation at the barrage stabilised on Thursday after reaching a peak at 11 a.m. on Tuesday, according to officials. However, a fresh spell of rain in Himachal Pradesh and Uttarakhand on Thursday morning could result in an increase in the flow of water on Friday, although experts say Delhi is unlikely to experience a worsening of the situation unless there is another cloudburst in Himachal or Uttarakhand.
The rivers comprising the Yamuna river system swelled to unprecedented levels, according to rainfall data from areas that drain into the Yamuna. Between July 8 and 10, the Himachal Pradesh districts of Sirmaur and Shimla, which are major Yamuna catchment areas via the Giri and Pabbar rivers, received over 200 millimetres of rain, which is double the normal amount. The Uttarkashi district in Uttarakhand, where the Yamuna begins at the Yamunotri glacier, received 133% more precipitation than usual between July 6 and July 12. The Dehradun district, which contributes water to Yamuna via lesser rivers such as Asan, Sunheri, Pabbar, and Aglar, received 139% more rainfall than usual between July 6 and July 12.
All of this resulted in a sharp increase in water flow at the Hathinikund barrage between July 10 and 11, compelling Haryana to open the sluice gates. The barrage, constructed in 1996 and put into operation in 1999 to supersede Tajewala, which was constructed in 1873, is located in Yamunanagar, in northern Haryana, and has ten main gates. At 2 p.m. on July 10, the water flow was 2.13 million cusecs, and it peaked at 3.59 million cusecs at 11 a.m. on July 11.
Since then, the water flow has decreased steadily; it was 61,019 cusecs at 6 p.m. on Thursday, leading to the closure of the gates at 6 p.m. on Thursday, which officials say will provide significant respite to several districts in Haryana and Delhi. The reopening of the gates will depend on the water flow from Himachal Pradesh and Uttarakhand, they said.
The average water discharge at the barrage in July is approximately one million cusecs per second.
The Chief Minister of Delhi sent a letter to the Union Government on Wednesday, blaming the water from the barrage for the deteriorating situation in Delhi. The water level in the Yamuna in Delhi is rising not because of rainfall in Delhi, but because of water discharged from the Hathinikund barrage in Haryana.” He requested that Union Home Minister Amit Shah limit the rate of water discharge so that “the Yamuna level in Delhi does not rise further.”
The issue was that a barrage cannot accomplish this. The Delhi chief minister himself admitted as much much later in the evening, when he said he received a phone call from Union Minister Gajendra Singh Shekhawat, who informed him that Hathinikund was “just a barrage” and lacked a water storage reservoir. The discharge of water from Himachal Pradesh has decreased, and the situation will improve. But it will take time for the Yamuna’s water level to reflect this,” Kejriwal said at a Thursday evening press conference.
Officials stated that heavy precipitation in areas of the Yamuna river system downstream of the barrage contributed to the inundation in Delhi. According to the India Meteorological Department (IMD), between July 6 and July 12, Yamunanagar received 400.6 mm of precipitation, which is nearly six times the average for that period, while Karnal received 186.2 mm, which is three times the average. Panipat received 131.3 mm of precipitation, four times the average amount.
This also caused several local monsoon-fed rivers, such as the Somb and Pathrala, which originate in the Shivalik highlands, to overflow their banks. A senior government official from Haryana stated, “It played a crucial role in the rapid increase of Yamuna water.”
Himanshu Thakkar, an independent expert who has conducted extensive research on river systems, remarked, however, that inadequate management of the Yamuna was one of the primary causes of the flooding in Delhi. “The peak flow of water from Hathinikund on July 11 was less than in 1978, 2019 and 2012-13, when it reached up to 9 lakh cusecs, indicating that the rains in the hills may have played only a minor role.” It is primarily due to what is occurring in and around Delhi’s Yamuna floodplains, he explained. In 1978, water flow was regulated by the Tajewala barrage, which was superseded by the Hathanikund barrage.
Thakkar noted that the effluent dumped into the river and the prevalent sand mining along its banks have diminished the Yamuna riverbed’s capacity to absorb water. Due to deforestation along flood basins and the disappearance of water bodies, there is very little flushing of water.
Officials in Haryana expect the water flow in the Hathinikund barrage to increase over the next two days, but remain encouragingly below the levels of July 11. After Tuesday’s lack of precipitation, Himachal Pradesh and Uttarakhand’s Yamuna catchment areas received additional precipitation on Wednesday and Thursday. Thursday morning at 8.30 a.m., Dehradun received 62 millimetres of precipitation, 220% more than normal. IMD has issued an orange alert for Friday for Himachal and Uttarakhand and a red alert for Saturday and Sunday.
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According to officials, it typically takes between 24 and 48 hours for rainwater from these two states to reach the plains. An official stated, “However, we do not anticipate a repeat of the June 11 situation in Delhi because there is very little precipitation downstream of Hathinikund.” Despite a potential increase in flow from Hathinikund, a second official from the Central Water Commission expects the water level in the Yamuna in Delhi to fall below 208 metres by Friday evening, given the absence of localised sources of rainfall.
