Thursday, March 26, 2009

River Flow Survey

River flow survey. It is the survey the Central Water commission undertakes every day in the all surface flowing rivers in our country. The main function of this survey is to assess the exact quantity of water available in the rivers irrespective of small or big.The another important work is to forecast the incoming flood to the places where river flows minimum 2 days in advance.The state Government always depend upon this forecast.

The Central Water commission established gauge sites in many points for one river so as to avoid human error as well as to asertain accuracy of flow. The data will be collected for particular river point for more than 10 years and then it will be shifted to other place of river.If the particular place is important the gauge site will be permanent and gauge observation will be taken without any interruption.
The river flow Survey is taken either by float system or by current meter system. Before establishing the gauge site a straight reach of min 1oo mts length is chosen. Before this reach there must not be curve in the river. In the chosen point A gauge post will be fixed. The base level will be fixed according MSL of the area,by undertaking level Survey. The point selected will be Centre line of gauge station. From this point 100 mtr up& down further two points will be fixed ,and gauge poles will be fixed.
Fixing of gauge post The gauge post is wooden post with metreement measur plate fixed on it.The gauge post will be fixed in such a way it will corrulate with each other. The first post will be inside the river indicating the river level. Every 5mtr distance the gauge post will be fixed on the central point.and the points selected in the upstream as well as downstream side from river watel level to top of bund.Every day at 8AM.12.00 noon,6.00PM the water level will be observed.At 8.00AM the flow of river will be observered.The river cross section is 3 times in a year in the 3 sections at 1o mtr interval and depending upon the surfaceof the river, in May (lean season before rain),Aug ( Rainy /flood season),October (After flood season) Flow observation The river velocity is taken either by float method ,by current meter etc. The will be biffercated by available means into 5mtr/10mtr depending upon the width of river.A visible float will be sent passing thro' the point( av.3 times).The time taken to cross from U/s side to D/s side point will be noted.This process will be done in all the points covering entire river water surface. The entire process will take 3 hrs time.
Then after wards the paper work starts based on the site observation for calculating the flow of river and velocity( speed) of the river and quantity of water passing in the river on this particular day and after calculation the result will be conveyed to main central station by wireless method.
Water samples will be collected daily and it will be analysed daily in the site office for the suspended particles as well as sand particles it is carrying . The sample water collected daily from the river will be sent to main division office for analysing chemical particles.
I am proud to associate this work from the field side for more than 3 years.The river is Wain Ganga ,a tributory to Godavari River and another Tributory to Mahi river. during my service life.

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