New Delhi, Oct. 4 -- The Delhi government is set to conduct detailed topographic and bathymetric surveys of the entire 48-km stretch of the Yamuna from Palla on the Delhi-Haryana border to Jaitpur on the Delhi-Uttar Pradesh border, in a bid to build a comprehensive picture of the riverbed, identify obstructed stretches and track changes in the river's course.
The Irrigation and Flood Control (I&FC) department invited bids on October 1 for carrying out the two surveys. Officials said the exercise will cover not only the river channel but also embankments, spurs, drains, islands, encroachments and ghats located within 100 metres of either bank. The bathymetric survey will examine the underwater profile of the river, with cross-sections to be taken at intervals of 250 metres along the 48-km stretch. The topographic survey, meanwhile, will prepare a contour map of the river and surrounding terrain, helping identify changes in its alignment and physical features.
"Both surveys will involve the use of electronic total station machines, echo sounders and sonar systems mounted on motorboats," a senior government official said.
Bathymetric mapping essentially provides an underwater equivalent of a land survey by recording water depths and the contours of the riverbed. Officials said technologies including single-beam and multi-beam sonar, acoustic Dopplers, GPS and motion sensors would be deployed from boats. The data collected through sound velocity measurements and other sensors will subsequently be processed to generate a digital representation of the underwater surface.
The survey is expected to provide inputs for flood management by identifying clogged or altered portions of the river and understanding changes in its channel. The findings will also be used while planning proposed riverfront development and future boat navigation activities.
According to officials, the project is estimated to cost around Rs 80 lakh and the selected agency will have eight months to complete the work. The exercise comes amid the government's earlier plans to undertake dredging of the Yamuna riverbed. Last year, the Delhi government had said it would approach the National Green Tribunal seeking approval for the first such dredging exercise. The proposed intervention was aimed at restoring the river's natural flow, reducing pressure on regulator drains and improving flood resilience in low-lying areas along the Yamuna.
Dredging involves removing accumulated silt, sludge and solid waste from the riverbed and is more commonly undertaken in smaller water bodies such as canals and lakes. The proposed survey will provide detailed data on the riverbed before any such intervention is planned, officials said.
Published by HT Digital Content Services with permission from Millennium Post.