@Pankaj,

Try Surfer ! a contouring and 3D surface mapping software program

http://www.goldensoftware.com/products/surfer

https://www.rockware.com/product/overview.php?id=129&utm_source=bing&utm_medium=cpc&utm_campaign=surfer2

Try Hydrognomon - Hydrometry calculations module

http://hydrognomon.org/download.html

Dear Pankaj Roy

you can use SPH method

www.sphysics.org

or use openfoam software

www.openfoam.org

Dear Panjape: you can use one of these programs: Exell Or GIS< or use the drwer but this take long time , greeting

Thank you very much Ivan Radevski for your quick response to my question. I have gone through the link that you provided. I downloaded the package and installed it in my system. From the interface, it seems not for my sole purpose. Any way I am trying to learn it. But, facing some problem in loading data set which prevented further processing of it. So far I have been trying with it...may I ask more help in future! 

Thank you very much Pooyan Nikeghbali and Abdul Atheem Mushtaha for your quick responses to my question. My sincere thanks to you all. So far I am try to find hands on hydrognomon suggested by Ivan Radevski. May I ask Atheem Mushtaha how can I prepare in channel velocity distribution diagram in excel/GIS? 

my dear;

you can sea:

http://www.crwr.utexas.edu/gis/gishydro04/Introduction/Exercises/Ex4.htm

https://www.youtube.com/watch?v=jEQpwaITkqg

http://criticalzone.org/national/research/local-discipline/boulder-geomorphology/

my greeting

Hi, you can try Qgis. It is an open source GIS software.

https://www.qgis.org/en/site/forusers/download.html

Dear Pankja,

You can try SAGA.

It is an open source and powerful GIS software.

Bests

have you try ODV ? http://odv.awi.de/en/home/ I dont sure, but I think it can make horizontal and vertical distribution of flow velocity in the ocean..

regards,

ramdhan

Thank you very much Abdul Atheem Mushtaha for your responses again. The second link of YouTube shows the cross section drawing from DEM which is not an issue related with my work. That can be done easily for considerably hilly areas, but its difficult for flat plain alluvial rivers. I guess, the first link is helpful for me. But thing is that the website is displayed with error in the later part due to which I couldn't go through the steps or the proper methodology. Looking forward. Thanks once again!

Thank you one and all for your indispensable suggestions to help improve my understanding and short out the real problem. I have got overwhelming responses from different experts of various fields. Frankly speaking I am little confused to chose which one is better for tackling the problem. Once again I want to repeat that I need to draw some Isovel (the line joining the same velocity points of water) within a river cross section.  I never work with any software to draw those line, therefore, I need immediate help! Looking forward!!

QGIS and GRASS are open source and very powerful. 

Q- GIS new version and ILWIS is also very much effective in different sorts of spatial analysis. Many "Spatial analysis" functions are available in both the softwares.

QGIS

@Pankaj,

Try Surfer ! a contouring and 3D surface mapping software program

http://www.goldensoftware.com/products/surfer

https://www.rockware.com/product/overview.php?id=129&utm_source=bing&utm_medium=cpc&utm_campaign=surfer2

Thank you very very much Rodrigo Alejandro León Loya, Kalyanjit Sarmah da and Rakesh Arya for your valuable suggestions.

Thank you very muchRaoof Mostafazadeh for your valuable suggestion and the links for softwares. To be precise, I am looking for open source software only. Thanks!

What I need to develop/draw is something looking like this...if anybody can do a favour! 

Origin, Surfer and MATLAB are very useful in making contour plots

 Thank you very much Vijayasree B.A for your kind reply to my question. Actually, I need to draw isovel within a channel/river cross section. Many of my friends have already suggested me but, I have not got a proper solution for that. Anyway thanks to all!

For vertical distribution of flow velocity i.e. velocity gradient, values as recorded by the Current Meter at a particular point of observation, may be plotted according to the selected scale and then a line graph may be drawn. For horizontal distribution of  flow velocity, all the values at different depths at different point of observations along the section line may be plotted and then isovels can be drawn. 

Golden software surfer is good solution.

Madam, from my perspective I would like to suggest you QUANTUM GIS. Its a very much user friendly version of RS & GIS software. Besides this you can also try ILWIS is also a open source software. Both of these softwares are quite simple for both GIS and Image processing relevant works.