# Talk:Alluvial fan

Can anyone tell me what the difference between a River delta and Alluvial fan is? If there is not a difference then perhaps the two articles should be merged? --Daleh T 07:50, 2 October 2007 (UTC)
There is no difference.  —Preceding unsigned comment added by Bonescrusher (talk • contribs) 16:44, 6 June 2008 (UTC) 
They are related yet significantly different.  A delta forms mostly underwater as a stream enters a lake or river.  Deltas have nearly level surfaces very near sea level or lake level.  An alluvial fan is terrestrial, not underwater.  It has a sloping surface that is highest at the apex where the stream emerges from the mountain front, usually in a canyon or gully.  Alluvial fans can be fairly steep in the case of a (normally) small stream carrying gravel and boulders which the stream can't transport without the help of a high gradient. I wouldn't want to merge the two articles, although they could be cross-referenced. LADave (talk) 20:34, 30 August 2008 (UTC)

"The deposits are usually poorly-sorted."
It would help to define "sorting" with respect to sediment. Its meaning here is unclear to the layman.  —Preceding unsigned comment added by 74.103.193.208 (talk) 08:04, 19 April 2010 (UTC) 

Thanks for pointing that out, the term is now wiki-linked to the Sorting (sediment) page, which hopefully is clear enough (the diagram helps I think). Mikenorton (talk) 19:31, 19 April 2010 (UTC)

I believe it was David Dawdy who developed the alluvial fan hydraulic analysis program for Baker. It would be good to include a reference to his probabilistic approach and a link to the model. FEMA has a runtime version of the program, but I cannot find a copy of the source code (BASIC).  — Preceding unsigned comment added by Drdbthompson (talk • contribs) 21:40, 27 June 2011 (UTC) 

I'm confused why the last few edits have removed the lead section and replaced it with an introduction header. Also, the rewritten introduction section now no longer has any links, and the citations there point to some biomedical essay... Should this be reverted? Gary600playsmc (talk) 13:45, 13 March 2019 (UTC)

This review is transcluded from Talk:Alluvial fan/GA1. The edit link for this section can be used to add comments to the review.
Reviewer: Reaper Eternal (talk · contribs) 06:45, 1 April 2022 (UTC)

Hello! Over the next several days, I will be reviewing this article and posting my thoughts here. I may also make minor corrections or improvements as needed. You can check the overall status of the article using the template below.
GA review – see WP:WIAGA for criteria

Is it well written?
A. The prose is clear and concise, and the spelling and grammar are correct: 

B. It complies with the manual of style guidelines for lead sections, layout, words to watch, fiction, and list incorporation: 

Is it verifiable with no original research?
A. It contains a list of all references (sources of information), presented in accordance with the layout style guideline: 

B. All in-line citations are from reliable sources, including those for direct quotations, statistics, published opinion, counter-intuitive or controversial statements that are challenged or likely to be challenged, and contentious material relating to living persons—science-based articles should follow the scientific citation guidelines: 

C. It contains no original research: 

D. It contains no copyright violations nor plagiarism: 

Is it broad in its coverage?
A. It addresses the main aspects of the topic: 

B. It stays focused on the topic without going into unnecessary detail (see summary style): 

Is it neutral?
It represents viewpoints fairly and without editorial bias, giving due weight to each: 

Is it stable?
It does not change significantly from day to day because of an ongoing edit war or content dispute: 

Is it illustrated, if possible, by images?
A. Images are tagged with their copyright status, and valid non-free use rationales are provided for non-free content: 

B. Images are relevant to the topic, and have suitable captions: 

Overall:
Pass or Fail: 

Cheers! Reaper Eternal (talk) 06:45, 1 April 2022 (UTC)


### Review
Lead section
Citations are not needed for material in the lead when the material is repeated in the body.
I've moved the citations into the article body. Where the body did not plainly state what was cited in the lead, the necessary material was added to the body along with the citations. --Kent G. Budge (talk) 17:07, 4 April 2022 (UTC)
The first couple sentences in the lead are too technical. Assume the reader does not have a background in geology and may not understand technical terminology. Try to keep it more like the last sentence in the lead, where if you do use a technical term ("nodal avulsion" in this case), you also give an explanation of what it means.
I've rewritten the lead sentence to be (I think) more comprehensible, without losing too much precision. The more precise description is moved into the body (and I may rework it further there.) --Kent G. Budge (talk) 17:07, 4 April 2022 (UTC)
Much better! Great job! Reaper Eternal (talk) 16:15, 18 April 2022 (UTC)
Wikilink the first occurrence of "sediment".
Done. --Kent G. Budge (talk) 17:07, 4 April 2022 (UTC)
As far as I am aware, alluvial fans do not come from point sources. Glaciers, streams, etc have width. Perhaps replace with just the word "source"?
Done. The cited sources do use the term "point source" but I can see this causing confusion, and it's not necessary to convey the idea. --Kent G. Budge (talk) 17:07, 4 April 2022 (UTC)
Source review
All sources appear to be reliable.
The short citations do not follow the style guideline in WP:CITESHORT. The full citations should be split off into a separate section below the short citations, and then the short citations should link to the full citations.
Done. --Kent G. Budge (talk) 18:12, 4 April 2022 (UTC)
Remove the abbreviations in what is currently citation #31. Specifically, "Intern. Ass. Sci. Hydrol. Gen. Ass. Toronto." is unreadable.
Done. --Kent G. Budge (talk) 18:15, 4 April 2022 (UTC)
Many citations go to 20 or more pages in an entire paper. This fails verifiability, since readers will need to page through the entire article to find the source. For example, citation 12 goes to an entire book and is used to support 5 different claims. Please link to individual page(s) or section(s) where possible. This should be solved as part of point two of my source review, since {{harvnb}} and {{sfn}} both provide options for page and section numbers. Alternatively, you could do it manually.
Mostly done. In a few cases, the very title of the paper, or its abstract, should be sufficient for verifiability. --Kent G. Budge (talk) 16:09, 7 April 2022 (UTC)
Wow. Very well done—this alone fixes the glaring issues with the article, so it should be able to be passed as soon as we've worked out the remaining minor kinks. Cheers! Reaper Eternal (talk) 16:23, 18 April 2022 (UTC)
When I attempted to spot check citation 5b, I was unable to find the source for the "1.5 to 20 degrees" claim in the article. This may be due to missing page numbers as just mentioned.
Scrambled the sources. This turns out to have been in Boggs; I've added a cite with the precise page. Going through others as well, in some cases finding better sources than the original. --Kent G. Budge (talk) 00:39, 5 April 2022 (UTC)
I'm going to start being a bit pedantic now. Sorry. :)

I've looked through some of the remaining short citations without locations / page numbers and noticed, as you mentioned, that they are sourced to the abstract. However, I believe (I might be wrong here, so please correct me if so) Harvard citations, which are what you're using, use [Abstract] instead of the page number when the citation goes to the abstract. I've made a few of these changes in the article, (specifically, citations #18 and #54), but could you finish this for citations to the abstract? Alternatively, correct me if I'm wrong.
Done. There are a very few sources (typically short web blurbs or news stories) where there just isn't a place to point to, but otherwise there are references now to either page numbers, section titles, or the abstract. --Kent G. Budge (talk) 18:56, 21 April 2022 (UTC)
On another citation (currently #40), I added the chapter number. I know the link goes directly to the chapter being cited, but it should still be included in the short citations for consistency with the manual of style.
Pedantic is good; Wikipedia has been around long enough now that we all need to be a little more ruthless. Yes, putting "abstract" as the location seems very reasonably and I'll try to wrap up doing so later today.--Kent G. Budge (talk) 17:34, 18 April 2022 (UTC)
One more minor nitpick:

The references should be in alphabetical order.
Organization & topics
This article's organization overall seems rather weak. All cleaned up now!

Section 1, "Size and geomorphology" is in the right spot, but the section title is too technical. This is the first section that the lay reader will read, so lets try to keep the section headings free of technical terminology. Would "Description" work better as a title?
Done. --Kent G. Budge (talk) 19:03, 4 April 2022 (UTC)
Section 2, "Formation" has two subsections. These subsection titles are filled with hyphens and unnecessarily refer to alluvial fans (see MOS:HEAD). Should the titles be rewritten to something like "Dominated by debris flow" and "Dominated by stream flow"? Speaking of hyphens, by the way, when I searched papers on this, it seems the majority just use one hyphen, as in "debris-flow dominated" or "stream-flow dominated".
The extra hyphen is because the direct reference to alluvial fans; removing those references removed the need for the second hyphen. --Kent G. Budge (talk) 19:03, 4 April 2022 (UTC)
Section 2.2, "Stream-flow-dominated alluvial fans", jumps around. It should first explain to the reader what they are before discussing other properties.
A lead paragraph has been added to introduce the concept better, and the remainder has been rewritten some. --Kent G. Budge (talk) 01:52, 7 April 2022 (UTC)
Much cleaner. Thanks! Reaper Eternal (talk) 16:35, 18 April 2022 (UTC)
Most sections in this article contain unnecessary references to the article title.
Should be better now. --Kent G. Budge (talk) 01:52, 7 April 2022 (UTC)
Sections 5 & 6, "In arid climates" and "In humid climates", should probably be combined. They could alternatively divided into subsections under one level 2 section heading (possibly just called "Climate" or "Climate effects").
They've been brought into an Occurrences section, together with the section on fans in other parts of the Solar System. --Kent G. Budge (talk) 19:03, 4 April 2022 (UTC)
Section headings should not be prepositional phrases.
Fixed. --Kent G. Budge (talk) 19:03, 4 April 2022 (UTC)
Section 6, "In humid climates", just gives two examples of alluvial fans, but doesn't tell me anything special about alluvial fans in humid climates. Are they bigger than average? Smaller? Wetter? Thicker? Do they flood more?
Not an independent section now. --Kent G. Budge (talk) 01:52, 7 April 2022 (UTC)
Is the second paragraph under section 7, "Flood hazards", useful to the reader? It does give an example of the risks of flooding in alluvial fans, but I'm not sure that level of detail is necessary. It seems more relevant to Koshi River or maybe Bihar. This also applies to the picture of the rescue efforts—I don't see what value this brings to the article.
Much more material on the special flooding hazards of alluvial fans, with sourcing. A second example has been added, and the Koshi example has been expanded to emphasize the megafan aspects. --Kent G. Budge (talk) 01:52, 7 April 2022 (UTC)
And I found a better image to illustrate this section -- a map of the actual flooded areas on the megafan. --Kent G. Budge (talk) 16:09, 7 April 2022 (UTC)
Thanks! The relevance is now a lot clearer. Reaper Eternal (talk) 16:35, 18 April 2022 (UTC)
Prose
These can be resolved in a number of different ways. I may give some examples of how I think the issues can be fixed, but if you can think of something that you prefer, that's probably better. It's your article after all.

Section 1: This sentence is not concise. Possible solution: "Alluvial fans vary greatly in size can exist on a wide spectrum of size scales..."
Fixed. --Kent G. Budge (talk) 01:52, 7 April 2022 (UTC)
Section 1: This sentence needs a rewrite since at first glance it appears to be self-contradictory: "The sediments in an alluvial fan are usually coarse and poorly sorted, with the sediments becoming less coarse toward the distal fan."
Reworded to sound less contradictory. --Kent G. Budge (talk) 01:52, 7 April 2022 (UTC)
Wikilink the first occurrence of "facies".
Done. --Kent G. Budge (talk) 16:09, 7 April 2022 (UTC)
Section 2: Could there be a better explanation of "toe-trimmed"? Is this really a common term for the eroded edge of an alluvial fan or should we just drop it? It's only mentioned once in an image caption.
The term pops up a few interesting references on a Google Scholar search. One is to a paper on Martian alluvial fans, where the toe trimming is interpreted as supporting evidence for a fluvial system. Than seems interesting enough to keep the mention -- I've added a mention of the Martian fans to that section with a source. --Kent G. Budge (talk) 00:37, 5 April 2022 (UTC)
Works for me if it's used in sources. Reaper Eternal (talk) 16:35, 18 April 2022 (UTC)
I'm glad you flagged it. I wasn't aware of the Martian toe-trimmed fans, and running across it while trying to establish the notability of toe trimming was a real treat. --Kent G. Budge (talk) 17:36, 18 April 2022 (UTC)
Section 2.1: This sentence is not concise. Possible solution: "Debris-flow-dominated alluvial fans are found to consist of a network of mostly inactive distributary channels..."
Rewritten. --Kent G. Budge (talk) 01:52, 7 April 2022 (UTC)
Section 5: The term, "fan-toe phreatophyte strips", should be defined for the reader. If the following sentence is supposed to be the definition, then the relationship should be made clearer. For example, instead of "Phreatophytes...characteristically form fan-toe phreatophyte strips. The phreatophytes may form sinuous lines radiating from the fan toe." try "Phreatophytes...characteristically form sinuous lines radiating from the fan toe sometimes (often? occasionally?) called 'fan-toe phreatophyte strips'."
Rewritten per your suggestion. --Kent G. Budge (talk) 01:52, 7 April 2022 (UTC)
Section 7: This sentence needs a rewrite: "Hyperconcentrated flows are intermediate between floods and debris flows, with a water content between 40 and 80 weight percent." Water concentrations have not been discussed before the "intermediate" claim, leading to a confusing sentence.
Better explained now. --Kent G. Budge (talk) 01:52, 7 April 2022 (UTC)
Section 7: Is the alluvial fan the part of the Koshi River that flooded? If yes, this should be explained in this section. If no, is this material relevant?
Explained now; relevance should be clearer. --Kent G. Budge (talk) 01:52, 7 April 2022 (UTC)
Section 8: The abbreviation "SAR" is defined but never used. It should be removed.
Done. --Kent G. Budge (talk) 15:06, 5 April 2022 (UTC)
I've done my final pass on the prose now, and here are a few things I found:

Section 2: "When there is enough space in the alluvial plain for all of the sediment deposits to fan out without contacting other valleys walls or rivers..." This is missing punctuation. I'm not sure if it's supposed to be "valleys' walls or rivers" (you really shouldn't use possessive case for inanimate nameless objects in most cases) or "valleys, walls, or rivers" (a list).
Section 2: Similarly, this clause is also missing something: "When the alluvial plain is narrow or short [and is (?)] parallel to depositional flow..."
Section 3.1: "Alluvial fans are characterized by coarse sedimentation, though with an overall proximal to distal fining." This sentence is a nightmare since it can be taken two completely different ways. I had to read it three times before I realized you were saying that the sediments become finer as you move from the source towards the distal edge. Additionally, most people aren't going to know the definition of "fining", so do you think maybe using a simpler and/or more verbose method of explaining the topic would be better? Your next sentence even explains this, so I'm just going to boldly condense the two into a simpler sentence. Let me know if you agree with the results.
Section 4.1: "The upwards coarsening of beds..." What type of beds? (I'm assuming stream / river beds, but that should be made clear for the reader.)
Section 4.1: Don't mix numerals and words when writing numbers, especially when they are less than ten million. Pick one or the other. (i.e. Use 10,000 or ten thousand, not 10 thousand.)
Section 4.1: "15,000 km2 (5,800 sq mi)". Pick one style. {{convert}} might have some option to force this, but I don't know it off the top of my head. Alternatively, just do the math by hand.
This should be the last group of things to fix and then this article should be ready to pass! Reaper Eternal (talk) 06:52, 22 April 2022 (UTC)

I've done my best to address these. Your tweaks look fine -- thanks. --Kent G. Budge (talk) 17:27, 22 April 2022 (UTC)
Images
Images need alt text for blind or visually impaired readers who are using screen readers.
Done. In some cases "refer to caption" seems adequate per WP:ALTTEXT. --Kent G. Budge (talk) 15:45, 5 April 2022 (UTC)
The fourth image has a short article for a caption. See WP:CAPTION.
Abbreviated considerably. --Kent G. Budge (talk) 15:48, 5 April 2022 (UTC)
Copyright
Enough spot checks are  Done that I'm satisfied. No close paraphrasing or copyright violations were found.
The newly-added image, File:Bihar Floods.jpg needs an appropriate image license. The link given on the image page is dead, but I was able to find a copy here on CERN's (!) website. Reaper Eternal (talk) 06:10, 22 April 2022 (UTC)
Hey Kent, did you see this? I can't find the copyright on UNISAT / UNITAR's website, and the user who uploaded it put CC-by-SA on it, but claimed to not actually know if that is correct. Reaper Eternal (talk) 14:42, 25 April 2022 (UTC)
Good catch. I dug around and found that it's licensed as CC BY-NC-SA 3.0, which is not considered an acceptable free work license by the Wikipedia Foundation. That might be fixed by replacing with a low-resolution version with a free use rationale, which is tempting -- it's such a nice image to illustrate the concept. Let me know if you think the image is valuable enough for that and whether a low-resolution image (which would blur most of the legend) is still useful. Otherwise, it's a pinch, but it will have to go. --Kent G. Budge (talk) 16:35, 25 April 2022 (UTC)
I've gone ahead and deleted the image as a copyvio. Thanks for that information. I'm no image expert, but I believe a low-res image would violate NFCC #1 and possibly #8, since a free equivalent could be created. In any case, it certainly isn't necessary to have a map of the Bihar flood for this article to pass GAN. Reaper Eternal (talk) 21:29, 25 April 2022 (UTC)
Overall
I'm going to stop reviewing this for now, and re-review it once you've fixed the issues mentioned above. As it stands, this article does not meet the good article criteria. Reaper Eternal (talk) 06:45, 1 April 2022 (UTC)

I'm going to go over the notes to be sure they're specific enough on page number (where this is possible; difficult for some online papers.) Should then be ready for further review. --Kent G. Budge (talk) 01:52, 7 April 2022 (UTC)
Okay, I think I've addressed all the concerns. Back in your hands. I'll add that even if the article ultimately fails GR, the review has at least resulted in the article being much improved. --Kent G. Budge (talk) 16:09, 7 April 2022 (UTC)
Kent, I don't think the article will need to fail GAN since you're doing a lot of good work on fixing the issues. I'm currently in the process of trying to get access to some more of the papers so I can do appropriate plagiarism / source verification spot checks. Once that's out of the way, I'll continue with my review. Thanks for all the work you've done so far! Reaper Eternal (talk) 15:14, 12 April 2022 (UTC)
Kent G. Budge, I can't seem to get access to most of these sources. I'm going to go ahead with this review under the presumption that you probably know how not to plagiarize since you have a PhD. ;) Does that work for you? Cheers! Reaper Eternal (talk) 04:37, 16 April 2022 (UTC)
Yes, that should be okay. I am reasonably careful about rephrasimg cited material to avoid directly quoting.--Kent G. Budge (talk) 16:14, 16 April 2022 (UTC)
This article now meets all criteria for good articles. As such, I am now passing it. Great work on this article—I feel like I learned something from it too! Reaper Eternal (talk) 21:32, 25 April 2022 (UTC)