The Sahibi River Originates in Jaipur Distt. of Rajasthan. After passing through Alwar Distt. in Rajasthan and Gurgaon Distt. In Haryana enters U.T. of Delhi near Dhansa. In the earlier years, the discharges in Sahibi used to moderate till the same reached Delhi. Due to interception of Jahajgarh and other jheels and the under ground reservoirs of Rajasthan and Haryana,very little quantity of water used to enter U.T. of Delhi. Due to land developments and improvement in Drainage system in Haryana, it is seen that every year, the quantity of water entering Delhi is increasing very fastly and the Najafgarh Jheel areas started remaining under water for full year. To check this entry of water in Delhi, the bund and regulator at dhansa were constructed in the Year 1964 and the same year there had been an unprecedented heavy flood in Sahibi which caused breach in Dhansa Bund and resulted in submergence of most of areas of Najafgarh Block in deep waters.
Similar instances of heavy flood in Sahibi have been in the years 1967 and 1977. Though the flood of 1967 did not make any damage in Delhi area but 1977 flood created even worse position than 1964, when even the far off colonies of Delhi like Janakpuri, etc. were threatened by the Sahibi Floods.
Every time after the flood in Yamuna & Sahibi different experts Committees had been set up who always recommended for increasing the capacity of N.G. Drain and Dhansa Regulator and also the raising of the banks to accumulate higher discharges inside them.
History of Past Flood by Sahibi Nadi:-
Sahibi river belongs to special category of rivers in arid and semi arid areas in Rajasthan. The Sahibi river occassionaly does rise in floods when ul0timately its flood water travels down upto Yamuna through Rajasthan, Haryana and Delhi. However in year like 1964 , it did cause considerable damage to agricultural area, roads and rail communications and villages in Haryana.
In Delhi flooding and consequent damage is caused mainly in the rural area of Delhi in and around Najafgarh Jheel. It also causes damage to the urban areas situated along the banks of the Najafgarh Drain. There is no record of flooding and damage in Delhi area prior to 1964, when the capacity of the Najafgarh Drain was only 900 cusecs. Even the Reddy committee which examined the problem of floods and drainage in Delhi in 1957-58 did not mention any damage caused by Sahibi floods in the past. The first major flood of Sahibi as known in the recent past occurred in 1964. The Dhansa bund which was constructed in 1961-62 suffered damage when the level U/s rose considerably. A controlled cut was made through Dhansa bund which later on widened and resulted in a breach and the flood waters could not be contained within the Najafgarh drain, thus caused damage both in the rural and urban areas of Delhi. In the years 1967, 1975 & 1976 the flood was of less magnitude and there was some damage in Haryana, without effecting Delhi as Sahibi water could pass down the Najafgarh drain through Dhansa regulator. The real major flood after 1964 was that of 1977.
Floods of 1977:-
During 1977 two major floods were experienced in the Sabhibi catchment, the first storm occured between 29th to 31st July and the second between 4th & 6th of August. The Yamuna was already in floods when the Sahibi rose in floods. The level of Yamuna on 27th of July at old Railway Bridge in Delhi was 204.85m(672.07ft.) against a danger level of 204.83 m (672 ft.). The maximum level of Yamuna recorded at old railway bridge in 1977 was 205.85m (675.29 ft.) on 7th August 1977.
The Water level U/s of Dhansa was 210 M (688.98 ft.) on 11.7.77 i.e. 2.5 M less than the FRL. It started rising gradually and reached a level of 210.80M (691.58 ft.) on 28.7.77. Thereafter due to floods in the Sahibi, the level started rising rapidly and reached 213.575 M (700.71 ft) on 6th of Aug. 1977 whereas top of the bund at Dhansa is at a level of 214 M (702 ft.). Anticipating such a high rise of water U/s of the bund Delhi Admn., had started from 2nd August, temporarily raising the bund by means of sand bags, and on this account bund remained safe. As the bund is not connected to high ground at its southern end, considerable flow started through that gap, which got further developed on account of high level on its U/S. During this period both the regulator were kept open and max. discharge of about 6000 cusecs was passing through regulators against the designed capacity of 3000 cusecs. It is roughly estimated that the max. discharge passed through Dhansa bund (Regulator as well as by-pass channel) was of the magnitude of 36,000 cusecs. On account of this heavy flow from Dhansa and also due to inflow from direct catchment of Najafgarh lake, the Jhatikara bund on the left-bank of Najafgarh Drain in Delhi breached on 6.8.77. Consequently the entire Najafgarh Jheel and vast area of Delhi came under submersion. The Najafgarh drain had a designed capacity of 3000 cusecs. Due to such heavy inflow, the Kakraula regulator was also by-passed and lot of water started flowing over-Najafgarh Dhansa road. The Najafgarh drain was carrying a discharge of about 6000-6500 cusecs for number of days against the designed capacity of 3000 cusecs. The excess discharge resulted in overflowing the banks of the drain inspite of the attemps made by Delhi Admn., to temporarily raise the banks by sand bags.
The max. level recorded D/s of Dhansa regulator was 212.80 M (697.98 ft) on 9.8.77 and the max. level recorded at Kakraula was 212.125 M (695.77 ft) on 16.8.77 and the same level was recorded at Basaidara on 17.8.77. The rural area in Delhi remained under water for about 3½ months and were free from submersion only in the second week of November.