Delhi floods: Why is there a flood-like situation in the national capital - Explained

livemint.com:

Lt Governor VK Saxena has called a meeting of Delhi Disaster Management Authority (DDMA) on Thursday to discuss the flood situation in the city while CM Kejriwal has urged Union Home Minister Amit Shah that water from Hathnikund barrage in Haryana be released in a slow and pointed out manner to prevent flooding in the national capital.  Furthermore, Kejriwal on Thursday informed that rising Yamuna levels have led to the water treatment plants at Wazirabad, Chandrwal and Okhla to be shut and it could lead to a water supply issue in some areas. The highly unusual flood-like situation in Delhi can be attributed to two major factors i.e.

increased rainfall in the national captial and surrounding areas and increased discharge of water from Haryana's Hathnikund barrage. According to CWC, the flow rate from the Hathnikund barrage remained 1.5 cusecs above the normal level at night.

The normal flow rate from the barrage is 352 cusecs but heavy rainfall led to increased discharge. One cusec is equivalent to 28.32 litres per second.

Meanwhile, Delhi saw the highest rainfall in a single day in the month of July since 1982. The national capital received 153mm rainfall in the 24 hours ending 8:30 am on Sunday which was followed by 107mm rainfall in the next 24 hours.  Principal director of the Natural Heritage Division at the Indian National Trust for Art and Cultural Heritage Manu Bhatnagar blamed heavy rainfall in a short period of time as the primary reason for the rising water level in Yamuna.  "The same amount of water falling over a longer period of time would not lead to such a situation as it allows time for the water to pass through.