Since the Hathinikund Barrage is not a dam and lacks either a reservoir for storage or overflow channels, a combination of unusually heavy rainfall in the upper reaches of Himachal Pradesh and Uttarakhand and environmental factors like the diminished absorption capacity of the riverbed and riverbanks and encroachment of the Yamuna floodplain have resulted in the unprecedented flooding. Although experts say Delhi is unlikely to experience a worsening of the situation — unless there is another cloudburst in either Himachal Pradesh or Uttarakhand — officials have stated that while the situation at the barrage stabilised on Thursday (it reached a high at 11 am on Tuesday), a fresh spell of rain in Himachal Pradesh and Uttarakhand on Thursday morning may mean an increase in the flow of water on Friday.
Data on rainfall in the Yamuna’s feeding regions indicate that these areas got rainfall substantially above average in the days before Wednesday, which caused the rivers that make up the Yamuna river system to overflow to previously unheard-of heights. For instance, the Himachal Pradesh districts of Sirmaur and Shimla, which serve as significant Yamuna catchment regions through the Giri and Pabbar rivers, got more than 200 mm of rain between July 8 and July 10, which is double the usual amount. The Yamuna originates from the Yamunotri glacier in Uttarakhand’s Uttarkashi district, which had 202.3 mm of rain between July 6 and July 12—133% more than usual. Between July 6 and July 12, the Dehradun area, which supplies water to the Yamuna via smaller rivers including the Asan, Sunheri, Pabbar, and Aglar, received 345.3 mm of rain, which is 139% higher than usual.
All of this resulted in a sharp increase in water flow at the Hathinikund barrage on July 10 and 11, which compelled Haryana to open the sluice gates. The barrage, which was constructed in 1996 and put into service in 1999 to replace Tajewala, which was constructed in 1873, is situated in Yamunanagar, at the northernmost point of Haryana, and has 10 major gates. Water flowed at 2.13 lakh cubic seconds between 2 p.m. on July 10 and reached a high of 3.59 lakh cubic seconds at 11 a.m. on July 11.
Since then, the water flow has progressively decreased; by 6 p.m. on Thursday, it was just 61,019 cusecs. This finally caused the gates to shut, which should be a huge relief for several regions in Delhi and Haryana. According to them, the decision to reopen the gates would be made in accordance with the water flow from Himachal and Uttarakhand.
At the barrage, the normal average water flow in July is close to one lakh cusecs per second.
It hasn’t rained in Delhi for the last three days, the frightened Delhi Chief Minister wrote in a letter to the Union Government on Wednesday, blaming the water from the barrage for the deteriorating situation in Delhi. Rains in Delhi are not raising the water level in the Yamuna; rather, water discharged from the Haryana-based Hathinikund barrage is to blame. He requested that Union Home Minister Amit Shah slow down the water discharge so that “the level of the Yamuna in Delhi does not rise further.”
Problem was, a barrage couldn’t do this. Later that evening, when he claimed to have received a phone call from Union Minister Gajendra Singh Shekhawat, who had said that Hathinikund was “just a barrage” without a reservoir to hold water, the Delhi chief minister himself acknowledged as much. “The amount of water being released from Himachal Pradesh has decreased, and things will get better. But it would take time for it to show up in the Yamuna’s water level, Kejriwal remarked at a news conference on Thursday night.
According to officials, the flooding that has occurred in Delhi has also been caused by heavy rainfall in regions that correspond to the Yamuna river system downstream from the barrage. Yamunanagar got 400.6 mm of rain between July 6 and July 12, which is about six times the average amount for that time period, while Karnal received 186.2 mm, which is three times the typical amount. Four times as much rain fell in Panipat—131.3 mm—than average.
As a result, numerous nearby rivers that rise during the monsoon, like the Somb and Pathrala, which flow from the Shivalik hills, became larger than they should have. An essential part was played in the rapid surge in Yamuna water, according to a top Haryana government official.
However, Himanshu Thakkar, a self-employed specialist who has conducted considerable research on river systems, stated that the Yamuna river’s mismanagement was one of the main causes of the floods in Delhi. The peak water flow from Hathinikund on July 11 was lower than it was in 1978, 2019, and 2012–13, when it even reached 9 lakh cusecs, indicating that the function of the hillside rainfall may have been restricted. According to him, the Yamuna flood plains in and around Delhi are the main culprit. To be sure, the Tajewala barrage, which was later replaced by Hathanikund, was responsible for controlling water flow in 1978.
Thakkar made the observation that the filth dumped into the river and the widespread sand mining along its banks had reduced the Yamuna riverbed’s ability to absorb water. Deforestation in the flood plains and the loss of water bodies result in very little water flushing.
According to Haryana officials, water flow in the Hathinikund barrage is expected to rise over the next two days but, encouragingly, remain below levels from July 11. This is due to the fact that on Wednesday and Thursday, in the Yamuna catchment regions of Himachal Pradesh and Uttarakhand, rain fell again after there was no rain on Tuesday. On Thursday morning, Dehradun got 62 mm up until 8:30 a.m., 220% more than usual. For Himachal and Uttarkhand on Friday, IMD has issued an orange advisory, and for Saturday and Sunday, a red alert.
According to officials, it typically takes 24 to 48 hours for rainwater from these two states to reach the plains. However, an official said, “We do not anticipate a situation in Delhi similar to that on June 11 again because there has been very little rainfall in areas downstream of Hathinikund.” Despite a potential increase in flow from Hathinikund, another Central Water Commission official predicted that the Yamuna in Delhi will drop below 208 metres by Friday evening due to the absence of concentrated sources of rain.
