A drainage basin refers to the whole drainage area of a river up to its confluence e.g. the Ganga-Brahmaputra-Meghna basin. When we say catchment area, it generally means the drainage area up to a certain point on the river, say a discharge observation site e.g. catchment area of Brahmaputra river up to Pandu. Watershed generally refers to the ridge line i.e. drainage divide of the basin, but is also used interchangeably with drainage basin. Thus, drainage basin and watershed can be said to be synonymous, but catchment has a different connotation. 

A drainage basin refers to the whole drainage area of a river up to its confluence e.g. the Ganga-Brahmaputra-Meghna basin. When we say catchment area, it generally means the drainage area up to a certain point on the river, say a discharge observation site e.g. catchment area of Brahmaputra river up to Pandu. Watershed generally refers to the ridge line i.e. drainage divide of the basin, but is also used interchangeably with drainage basin. Thus, drainage basin and watershed can be said to be synonymous, but catchment has a different connotation. 

They are all the terms used in a hierarchical sense with basin being the largest, catchment next and watershed at the lowest level. We can further divide watershed into sub-watersheds and micro-watersheds.

You may also want to read the definitions on Wikipedia at https://en.wikipedia.org/wiki/Drainage_basin

In my opinion catchment, watershed, river basin are used by different authors for the same meaning.

Thank you very much Dweependra nath Kalita, Ghulappa S Dasog and Chong-Yu Xu for your interest and kind responses! The terms catchment, drainage basin, watershed are interchangeably used. But, my main concern here is that do we have common consensus or standard methodology of its mapping? Looking forward....thanks once again!! 

Earlier, when we used planimeters, we went along the drainage divide from the outlet and measured the area, or sometimes traced the area on tracing graph papers and measured it. Nowadays the map-making features of GIS software are quite handy. I personally like ILWIS and MapWindow, but the principle obviously remains the same. That way I think the methodology is pretty standard. Regarding common consensus of mapping, I am not aware. I will also like to know if there is such a thing. 

please visit www.india-wris.gov.in

Indeed, these terms may overlap & coincide. The best thing is for the "user" to define exactly what he/she is talking about & thus carry on safely with the research according to the purpose at hand.

Delineating a drainage basin has to deefine 3 major aspects of the water in that basin: 1. Source(s); 2. Paths / with their water consumption (either by humans & biodiversity, or by natural surface/subsurface flows; 3. Outlets where water (surface/subsurface) is going/leaving the basin.

I  am  agree  to Chong-Yu Xu 

Catchment, watershed, river basin are used by different authors as synonymous.

I think in every book  and article  must first clearly define these words .

Hi, Pankaj. About the methodology of catchment mapping, there are some methods of catchment mapping using geographic information systems. There is a radar mission called SRTM that sampled worldwide elevation data in 30 m resolution.These data might be used to delineate catchment areas by morphometric analysis in GIS softwares.

Fortunately some of these sotwares are free, as Quantum GIS (QGIS). QGIS has a plugin that may be used to preform the task you are looking for.

A drainage basin or catchment area is an extent or an area of land where surface water from all types of precipitation and ground water (hydrogeology) from different recharge areas of the basin converge to a lower elevation point, usually the mouth of the river or outlet of the basin.

Whereas the term watershed is an area or ridge of land that separates waters flowing to different rivers, basins, or seas. Commonly it is used to mean a drainage basin bounded by the drainage divide, i.e. the perimeter with higher geographical features (such as a ridge, hill or mountain) forming a barrier of that area dividing one basin from the next.

But the topographic drainage divide and hydrogeological drainage divide both are not always the same, because ground water contribution into a drainage basin depends upon the location of the recharge area. Suppose there is a N-S trending ridge formed by a cuesta or hogback comprising bedded sedimentary rocks, which happens to be the drainage divide. If the beds are dipping towards east, then the recharge area of the rocks will extend further to the west of the topographic drainage divide. In such a case the hydrogeological water divide line will have to be extended further west of the topographic drainage divide to enclose the recharge area also. Hence the topographic divide will be not the true drainage divide in such cases. In this context the term watershed may be differentiated from drainage basin or catchment area.  But many authors consider them as  synonymous as mentioned by Chong-Yu Xu  and Reza Khoshraftar.

 in scientific literature the "drainage basin" for the British and the "watershed" in US English.

For more information click on the following link:

http://www.hypergeo.eu/spip.php?article483

Thank you very much every one for your interest and time especially to them who have given links! Sir, Jogendra Nath Sarma thank you very much for enlightening with the concepts.

Sir, Kenneth M Towe, I have seen the paper of A N Strahler. The paper reviews the quantitative aspects of basins but not the delineation methodology what is the main concern of mine. Anyway thank you very much. Looking forward from senior scholar like you all.

to prepare a drainage map, kindly digitize the finger tip or first order stream, then second order and so on. feed the attribute table. clean and build your vector layer you will get not only your streams with orders as a vector layer but also the total number of first order stream and others separately and also the length of each stream order in the attribute table. now since you have dizitized all the stream of a basin or sub-basin or water shed or sub or micro watershed of your AOI your can easily delineate the basin boundary as a polygon vector layer. after getting the all these info you can calculate all other morphometric parameters for your study. regards

Are catchment basin and drainage basin synonymous? If so, what are the criteria to delineate a drainage basin?

In theory all the concepts are the same, but there is another, more deificil assess groundwater basin.

To draw a topographic watershed, or digital elevation model (DEM) map is used, the line must start and end at the same point. Must be careful not to get out of the watershed or watershed divide.

Due to good progress in the technology , I think , the best way to specify of  drainage basin  or catchment is , use of GPS , field work and topographic maps with  appropriate scale .

In a pure geological sense, drainage basin, watershed and catchment area are synonymous and used interchangeably in scientific notes, while in the community of hydrology, more often than not, catchment area is preferred and drainage basin is rarely used.

By definition, all these 3 represent an area, within which, all the water will drain to a single point, which is defined by their pour points.

Thank you all for your time and responses!

My general observation is that scholars are agree with the synonymity of catchment, drainage basin and water shed. But, a few scholars have forwarded their views on criteria to delineate a catchment.  

I've just change the sequence of the questions so that hopefully, we can make a general consensus.

good luck defining its downstream end / or the lateral-width at the downstream end if you decide to arbitrarily cut off the area somewhere

Pankaj, as many of the others have stated, I believe that catchment, watershed, and drainage basin are fairly synonymous. However, this appears to be based on the scale of your study. As is typical in the geological sciences, there are many terms that describe the same the same process or parameter. In terms of delineation, you may consider the National Watershed Boundary Dataset (WBD) as an example, http://nhd.usgs.gov/. In this case, they have designated 8 nested levels of closed-basin delineation. In this case, a user can determine the delineation precision or watershed boundary based on the study objective.

Dear Pankaj,

I have been waiting for the views of other colleagues, and I read the contributions with much of interest. It seems to me that it has not been mentioned what I am about to say, I would like to add my two pence opinion to the discussion.

Most of the contributors agree what you, Pankaj have  concluded that these terms can be used interchangeably. In my view it is true in many cases, but not exactly.

The difference is related to the scale.

At any scale you can speak about watershed: from a big river down to a small piece of land, a part of a cultivated plot, a corner of a garden, or even if you do analog modelling of the erosion, a small area of a decimeter scale sandbox model.

This is more or less true for the term catchment, maybe some of the colleagues would not use this term for a set of rills or for the part of the sandbox model.

And, IMHO, what distinguishes the drainage basin from the other two terms, for that you need definitely at least a few confluences of watercourses (for the planet Mars maybe paleowatercourses). I am mentioning that because at the scale of the soil particles, gravels, cobbles or boulders, or especially in case of an unsorted glacial till, one can still define runoff-models based on e.g., laser scanning (LiDAR) data that would include catchments, but certainly there are no proper watercourses (to apply e.g., the classic Horton's, Strahler's or Shreve's rules) because some particles may reach or exceed the scale of parts the "drainage basin". At that scale the classic drainage basin cannot develop.

Therefore my conclusion would be that above a certain scale they can be used interchangeably (must be proper used), but on small gully and rill scales (and below) they are different.

Thank you for the interesting discussion and kind regards,

Balázs

In order to delineate a drainage basin on a SOI topographical sheet, the line to be drawn starting from confluence point of that particular stream following middle portion of the ridges (round shaped contour lines) just beyond the first order streams.and return to the starting point.  The line should be drawn in free hand without much crenulations like contour lines. This line will separate this particular drainage basin from the adjacent basin as watershed. 

If the drainage basin is marked in GIS environment, then after digitization the vector layer can be overlaid on satellite image.  

Criteria (criterion) could refer to the bases (basis) for an action, but in the context of this question, we assume “criteria” to mean the step-by-step methods or procedure for establishing the limits of a drainage basin. To delineate means to delimit or to mark out or to draw a line indicating the limits of a geometric figure. So, to delineate a drainage basin implies establishing its exact boundary in relation to any other contiguous drainage basin(s).

Technically, a drainage basin is a hydro-morphological unit or area on the surface of the earth which supplies water, sediments and other fluvial materials to a river or a network of rivers.

            The first step in delineating a drainage basin is to precisely establish or identify the river or river network that drains the basin in question.

            The second step is to use a topographical map and identify all the summits or closed contours and interfluves surrounding the basin that is being delineated.

            The third and final step is to run a partitioning or dividing line through the identified summits and interfluves and ending at the outlet. The shape that emerges is the drainage basin so delineated.

Inasmuch as a “catchment” defines the area from which a drainage basin catches or derives the water that sustains it; and a “watershed” is the area that sheds surface water to a basin; and a “drainage basin” is the area that supplies water to a river network, the three terms are simply synonymous.

Thank you very much Sir, Christopher L. Shope, Balázs Székely and Joel Umeuduji for  your kind attention and meaningful replies to this discussion where we arrive in a general consensus. From your replies, and as per my understanding, one thing is clear that the terms are scale specific. Yes! it is. If we consider the scale and put them in a descending order it will look like this: "Watershed>drainage basin>catchment" (Reverse to Ghulappa S Dasog's order). But, if we use them in a most generic way ignoring the parameter of scale, these terms can be considered as synonymous as most participators (Dweependra nath Kalita, Chong-Yu Xu, Jogendra Nath Sarma, Mohamad Radwan Khawlie, Reza Khoshraftar, Luis g. Salazar Mondragón, Ramendra Sahoo, Joel Umeuduji ) of this discourse are agreed upon and seen to be used interchangeably in literature. 

Thank you very much once again for your time and replies. Please don't forget to direct me towards the correct conclusion especially in case of hierarchical ordering of them and anything else which may related to this issue. 

I think, the perfect and precise delineation of catchment/drainage basin/watershed needs its proper definition as well as a step-by-step methodology. This is not a problem of me alone but for many others all over the world. 

Special Thanks to them, who forwarded their ideas, views, experiences and technical skill and methodological narratives to delineate a drainage basin either in a traditionally accepted manual or a modern ways.

Thank you all once again especially to them whose names I didn't mention above.

Frame work of watershed

                                       base map for delineation

regions                          1:6 M scale

basins                             1:1 M 

catchments                      1:1 M

sub catchment                  1: 250,000

watersheds                      1:50,000

sub watersheds                1:50,000

micro watershed                1:50,000

Thank you Shukla Acharjee for enlightening the discussion!  Hope this scale base classification or framework is in reference to Central Water Commission (CWC), India. I think we all have good time to go little deeper. Is this classification universally acceptable?

If we delineate the watershed based on the stream ordering of a particular drainage network and we may get 'n' number of ordering. Hypothetically, lets say 5 is the highest order of a drainage system. Which order of watershed can be considered as sub watershed or micro watershed for that particular drainage system?

Is it recommendable or convenient to delineate a micro watershed at 1:50,000 scale?