EARTH 123Introductory Hydrology
- Units
- 0.50
- Faculty
- Science
- Subject
- Earth Sciences
When it runs
- F24
- W25
- S25
- F25
- W26
- S26
- F26
- W27
- S27
Ran in 5 of the last 7 terms. Winter 2027: scheduled, 2 lecture sections. Spring 2027: schedule not out yet.
This course is intended to provide students with a practical overview of the hydrologic cycle and all of the interesting ways water flows and interacts with its environment, both surface and subsurface. The material is both qualitative and quantitative in nature and focuses on the circulation of water through the atmosphere, soil, groundwater aquifers, as well as looking at both the global fresh and marine water systems. Emphasis is placed on the physical aspects of hydrology, and the geologic and environmental factors that control the occurrence and cycling of water on Earth, as well as the impacts caused by population growth, contamination, urbanization or land use management, and climate change.
Prerequisites
None listed.
Antirequisites
None listed.
Leads to
Fall 2026 sections
| Section | Class | Enrolled | Meets |
|---|---|---|---|
| LEC 001 | 6975 | 168 / 250 | MWF 08:30–09:20 |
| LEC 002 | 7278 | 50 / 53 | Online or by arrangement |
Winter 2027 sections
| Section | Class | Enrolled | Meets |
|---|---|---|---|
| LEC 081 | 7632 | 0 / 225 | Online or by arrangement |
| LEC 701 | 8077 | 172 / 9999 | Online or by arrangement |
Reviewed on UW Flow
92% liked it88% easy65% useful
From 102 ratings and 30 comments on UW Flow. The most helpful comments, quoted as written, without names. Read them all on UW Flow.
Waste course, I only took it because I needed a science credit.
Jan 2018 · didn’t like it · 2 found this helpfulOn UW FlowRemove this
Pretty bird but in-person final
Aug 2026 · liked itOn UW FlowRemove this
As an engineering student, this course was refreshing. I’ve always enjoyed learning about the environment, so it was nice to learn about hydrology. The only downside was the frequency of deliverables - every week, there’s a quiz and either a discussion post or assignment. Moreover, there’s a lot of content for the final but if you have a good cheat sheet, you have nothing to worry about. Although the content may not be related to your degree, it’s semi-relevant to everyday life and is nice to know. I would recommend this course as a science elective.
Aug 2026 · liked itOn UW FlowRemove this
Easy NSE if you're in engineering. only downside is that there's now a final exam for the course (or at least there is one if you take the online version) and there's alot of material to cover.
Jul 2026 · liked itOn UW FlowRemove this
Good course for Pure Science breadth requirement if you're not a SCI 206 person. Ended with low 90 without going to lecture and studying exclusively for ~5 hours before the final exam. :3
Jan 2026 · liked itOn UW FlowRemove this
Discussed on r/uwaterloo
19 posts and comments in 19 threads mention EARTH 123, August 2013 to December 2024. Quoted word for word, newest first; each reply sits under the post and the comment that started its branch. Search r/uwaterloo for newer posts.
Fall 2024
Winter 2025 Bird courses - ARTS 2 points, 1 comment
“So I'm in 3B doing a double major, and last term while I was on coop trying to plan out my last 3 study terms, I noticed I had about half the required courses for a PSCI minor, so I thought why not …”
u/Horiphic: “… EARTH 123 and 223 are a great duo if you're interested in hands-on hydrology labs, and EARTH 122/121 are easy bird courses as well. …”
Spring 2024
Earth123 Discussion Post 2 1 point, 0 comments
u/Downtown-Demand-633: “Hey all! To anyone who's taking EARTH123 this term. Can you let me know what Discussion Post 2 was about? If you have had a copy of the discussion page, that would be great! Thanks!”
Increase of Enrolment cap in EARTH 123 Online (350 to 425) 32 points, 4 comments
u/KBDEARTHSCI: “… I just wanted to spread the word on a new enrolment increase in our Earth and Environmental Sciences online course this Spring - EARTH 123: Introduction to Physical Hydrology. …”
Winter 2023
CS kid looking for which is a better elective to take ONLINE - EARTH 123 or 121 2 points, 2 comments
u/Ok_Macaroon_8323: “Taking the course online this summer and by better I mean less of a time sink just want to finish this pure science requirement, thanks.”
EARTH 121, EARTH 122, EARTH 123 4 points, 15 comments
u/ananymouse23412345: “Gotta take one of these. EARTH 121 - Introductory Earth Sciences EARTH 122 - Introductory Environmental Sciences EARTH 123 - Introductory Hydrology Anyone taken before? Any advice? Which one is the easiest? Heard 121 doesnt have an exam, is that true for the other 2 courses?”
Fall 2022
Earth Minor 5 points, 4 comments
“Would love some easy course suggestions for earth! Already took 121,122,123 and first year labs. Gonna take 281 next term. Throw in a few upper year birdy chem courses too(except 220) Thanks!!”
u/Fluffy_State_5360: “how was EARTH 123?”
Spring 2021
Easy Science courses, including 300+ 1 point, 3 comments
“Hi all, I have a new grad offer for my dream job and just want to graduate as soon and painlessly as possible. …”
u/Laeriana: “EARTH 121, 122 or 123 might be good options to look at! I've also taken SCI 238 in a regular (non-pandemic-induced) online offering which might be a good option to expand on some of the physics concepts you've seen in 111. …”
Winter 2021
Easiest BIOL, CHEM, EARTH, MNS, PHYS, or SCI course? 9 points, 8 comments
“Got waitlisted for a class I wanted to take in the spring and will need 0.5 credits from any science course for my program (this would be after taking all the required courses for my desired minors). …”
u/Listired17: “EARTH 123 with Keith! (Not sure if it’s offered in spring though)”
Fall 2020
Is a environmental resources and sustainability minor good with Chem major? 4 points, 7 comments
“Just wondering what people’s thoughts are. I am majoring in honours chem but I am wanting to use what I learn in chemistry to help the environment. …”
u/E-is-for-Egg: “Are you a good writer?”
u/Fickle_ficus: “… 4 electives that would be suited to your chem background are: BIOL 354 (prereq CHEM 120 or 121), ERS 484 (prereq ENVS 200), GEOG 405 (prereq ENVS 200 & GEOG 209 or EARTH 123), & GEOG 368 (prereq ENVS 200)”
Good prof appreciation thread 61 points, 89 comments
“This term sucks a lot and a lot of people are having some shitty experiences, especially with certain profs/TAs/instructors. But there’s a lot of profs who are not that shitty. …”
u/DaTheta: “Keith Delaney in EARTH 123 is hella helpful during this term. He has really good in depth lectures, some may take a bit of time but you can also just speed the vids up a bit in inspect. He talks at a good pace though so I rarely do that. …”
Spring 2020
No pre-requisite on-campus courses for Fall? 4 points, 1 comment
“Are there any courses that are being offered on campus next term and have no pre-requisites? (apart from MATH 135/137)”
u/2kofawsome: “… The same thing for EARTH 223 and EARTH 123.”
Water related courses and research 6 points, 7 comments
“I'm an undergrad planning student and I've realized that I'm really passionate about water and hydrology related studies (ex./ watershed management, looking at the relationship between water supplies …”
u/Laeriana: “The only water related course I've taken is EARTH 123, which might not exactly be the kind of course you're looking for. If you're interested in Hydrology though, I would highly recommend checking out UW's Water Institute. …”
Check it elsewhere for Fall 2026
- Undergraduate Calendar, 2026–27The official entry
- Requirements for Fall 2026Waterloo’s requisite checker
- Schedule of Classes, Fall 2026Instructors, rooms, live seats
- Quest Class SearchWhere you enrol
- Course outlinesSyllabi from past terms (UW login)
- UW FlowStudent ratings and reviews
- WClassesPast sections back to 2004, and who taught them