Environmental Impact Assessment of Hydro Project

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Figure 1: Rupin Hydro Electric Project-Nargani Barrage Site

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Figure 2: Rupin Hydro Electric Project- Power House Site

Though seven locations were analyzed on factors like environment, economy, water availability, peaking power, cost of structures and infrastructure, head/location of diversion structures etc. for the project, the present project location was selected because the construction of dam on Rupin River, downstream the confluence the river with Nargani River, would increase the power generation output, thus bringing an effective cost-benefit Ratio.

The project location Map is shown below.

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Figure 3 Project location State

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Figure 4 Project location District

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Figure 5 Project Location topography Map

Salient Features

The river catchment area of River Nargani is 168sq.kms, while that of River Rupin is65 sq.kms. On the other hand, the snow fed catchment area of River Nargani is 31.5sq.kms, while that of River Rupin is 8.4sq.kms. While the average net lean season flow of the area is 4.65 cubic meter per second, the minimum net lean season flow of the area is 4.1 cubic meter per second. With rain, snow and glacier melt being the source of runoff for the area, the average annual rainfall in the area is 95.8 centimetres. The flood discharge for 50 year frequency at Nargani diversion site is 1500 cubic meter per second and at Rupin diversion is 700 cubic meter per second. The flood discharge for 500 year frequency at Nargani diversion site is 2150 cubic meter per second. At Nargani site, 6 Barrage bays are proposed, each of 11 meters width and a vertical lift gate of 6.25 meters. The reservoir capacity is 85,200 cubic meters, with full reservoir level at estimated 2206 meters MSL and minimum draw down level at 2202 meters MSL. On the other hand, at Rupin site, the trench weir crest is planned at 2207.16 meters MSl, with flushing discharge of 7.85 cubic meter per second and flushing velocity being greater than 3 meter per second.

The barrage across Nargani River is planned to be at a distance of 2.6 kilometers from Upstream of the confluence of Rupin and Nargani Rivers, The Trench Weir at Rupin River to be at a distance of 1.9 kilometers from Upstream of the confluence of Rupin and Nargani Rivers and power house site at 5.9 kilometers from downstream of the confluence of Rupin and Nargani Rivers. The project envisaged to be completed in 4 years, excluding the pre-construction activities is estimated to cost Rs.392.61 crores , generating 4.58 Kilowatts of electricity per hour, once completed.

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Figure 6 Project lay out plan of Rupin Hydro-electric project

The planned civil engineering structures to optimize the power potential of Rupin and Nargani rivers are: Diversion Structure at River Nargani, Intake and Feeder Tunnel at Nargani site, Trench Weir at River Rupin, Desilting Basin cum storage tank, Intake and Feeder channel to desilting basin cum storage tank, Tunnel Intake, Headrace Tunnel, Surge Shaft, Pressure Shaft/ Surface Penstock, Surface Powerhouse, Tailrace Channel, Switchyard, Transmission and Energy Benefit. The infrastructure facilities planned as part of the project are: Main Access road to the project, access roads to project components: tunnel; surge shaft; outlet portal; Dam site, Residential and non-residential buildings: Workshops; offices etc.

Environmental Description

The below details provide environmental status of area in 10 kilometers radius from the each of project locations: Dam site, Diversion Site and Power house site.

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Figure 7: Study area around project sites for Environmental Description

Meteorology

The district’s climate based on altitude varies from sub-tropical to temperate. While subtropical climate is observed in southern low tracts of the area, temperate climate is observed in northern and eastern high mountains. There are four seasons observed in the region: Summer in the months of April-May-June, Monsoon during July-August-September, Post-monsoon during October-November and Winter in the months of December-January-February-March. The areas precipitation is seen in form of rain and snow. The area has very good rains in the monsoon season and has little rains in for of snow in winter season. The climate at the project site is observed to range from subzero to 35 degree Celsius. Also, the climate is warm in summers which are driest part in year, humid in monsoons, cold in winters.

Air Environment

The Rupin Hydroelectric project, lies in an area which is clean from any of the harmful air pollutants as no industrial facilities operates near to project site. With the fact that most of the area within 10 kilometers radius of the project site lies under forest cover, any pollutants released from human interferences and activities are absorbed. The impact on air quality by hydroelectric projects are not direct but indirect due to cutting of tress for building civil structures or muck disposal and the transient emissions are only limited to construction phase.

The readings taken for three seasons i.e. Pre-Post monsoon and winter at air quality monitoring stations established at three villages around the project site i.e. Gaon Pujarli, Jiskun, Gosungu provide following results:

Particulate Matter (PM10)

While central pollution control board’s (CPCB), year 2009 standards allow for 100 μg/m3, for eco-sensitive areas including rural, residential and industrial areas, the 24 hours average PM10 levels recorded at the three stations during pre-monsoon, post-monsoon and winter seasons are 54.99 μg/m3, 52.40 μg/m3 and 56.56 μg/m3.

Particulate Matter (PM2.5)

While central pollution control board’s (CPCB), year 2009 standards allow for 60 μg/m3, for eco-sensitive areas including rural, residential and industrial areas, the 24 hours average PM2.5 levels