60-A Dissertation on Environmental Flow Requirement For A Critical Reach of Beas River.

Abstract

Environmental flows assessment is a process which determines the allocated water for maintaining aquatic habitats and ecological processes in a environment. The river system attains zero flow in low flow period due to construction of hydropower generating structures, water retaining structure and withdrawal of water by water users, which possesses a tremendous threat to the environment, ecology & aquatic life. Therefore a need arises to regulate the reservoirs for releasing the adequate water in the river throughout the year as well as a flushing flow once in a year. Thus environmental flow assessment for Beas river is also requirement. In the present study the assessment of the environmental flows of Beas basis has done by Tennant method and Flow duration curve method. The origin of river Beas is in the Himalayas in central Himachal Pradesh, India flows from a height of 14,308 ft at Rohtang Pass, Himachal Pradesh, from where it flows through the Kullu valley towards south, adding from various mountains bound tributaries. The river crosses Mandi and turns west, flowing into the Kangra valley at Sandhol at 1,940 ft above sea level. The river is divided into three paths and again joins back after crossing Mirthal at 980 ft above sea level. The Beas attaches the Shivalik Hills in Hoshiarpur and turns north, making a boundary with the Kangra district, separating the Gurdaspur and Hoshiarpur districts. Beas Coming down from the valley and enters into Punjab at Kapurthala, and turns south and meets into the Sutlej River at Harike. Two dam are constructed on Beas river ,first is Pong dam and second is Pandoh dam. The Png construction began in 1961 and completed in 1974 .The Pong Dam is an earth fill embankment dam on the river Beas in Himachal Pradesh, India Just upstream in Talwar District. The Pandoh Dam is an embankment dam on the Beas River in Mandi, Himachal Pradesh, India. Under the Beas Project, the dam construction work was completed in 1977. Beas has numerous tributaries. They are known as Bain, Banganga, Luni, Uhlal, Awa, Banner, Chakki, Gaj, Harla, Mamuni, Parvati, Patlikuhlal, Sainj, Suketi and Tirthan. This study is illustrated how each estimated environmental flow duration curve can be converted into a continuous monthly time series of environmental flows using a simple spatial interpolation procedure. The final environmental water demand is therefore presented in the form of a flow duration curve and as the mean monthly flow by Tennant method. By Tennant method, environmental flows for twelve months are 996, 910, 924, 1203, 1203, 1203, 1203, 1203, 1203, 1203, 1203, and 971 m3 respectively from January to December . In 2010 environmental flows for twelve months are 902, 934, 1439, I775, 1775, 1775, 1775, 1775,1775, 1775, 1652,and 1213 m3 respectively from January to December. By Flow Duration Curve (FDC) method, total discharge per days comes as 2140470 cumec. The discharge values are 1582570, 1222005, 942710, 755755 cumec respectively under class A, B, C and D. The EMCs value are 73.936, 57.091, 44.04, 35.31 % for class A, B, C and D respectively.