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The Hydrology Reddit

Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability. A practitioner of hydrology is a hydrologist, working within the fields of earth or environmental science, physical geography, geology or civil and environmental engineering.

Domains of hydrology include hydrometeorology, surface hydrology, hydrogeology, drainage basin management and water quality, where water plays the central role. Oceanography and meteorology are not included because water is only one of many important aspects within those fields.

Hydrological research can inform environmental engineering, policy and planning. The term hydrology is from Greek: ὕδωρ, hydōr, "water"; and λόγος, logos, "study".

Wikipedia: hydrology

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Future thoughts

So I’m a freshman environmental science major at Virginia Tech right now and I’m starting to develop an extreme interest for geophysics, geoscience, and hydrology. I’m super interested in the movement of sediments and water as well as water management and geology. I’ve also been super into looking at maps of rivers with tons of cool data put into them (like river migration, flow rates, ect). I would like to do these things in my professional career no doubt. Will Environmental Science get me into those industries? Or do I need to switch to an engineering major (civil/environmental Eng), or even something like a geology major? I’ve looked at my table of classes and environmental science takes a TON of chemistry, hydrology, geology, and geoscience classes. Switching is extremely difficult and I personally feel like if I just get the envsci degree and get lots of experience with internships and research I shouldn’t have much trouble getting a job in the fields mentioned in the beginning….right? I feel like I have to make a decision ASAP cuz every semester I spend here is costing me a BAG. I’ve talked with my advisors but I’m curious to hear what people on Reddit have to say.

05:16 UTC


GW in python path

Groundwater modellers who use python exclusively, what coding path did you take to learn everything you needed to use python effectively in groundwater modelling?

I am a hydrologeologist with 7 years of work experience, but I am looking for some new challenges. I want to become a GW modeller because my company currently does not have one and it looks like fun based on what I have seen from the USGS. However, I would prefer to go the flopy route over modflow to avoid the GUI.

This is the plan I want to follow, but would appreciate feedback.

I am currently taking the Python for everybody course through Michigan State on Coursera as a starting point. I want to supplement that with a few additional free fundamental courses and then dig deeper into Numpy, Pandas, and Mayplotlib. Then I would like to work on some of the easier 1D and 2D python flow modelling from the Australian Water Science School to ease into the 3D modelling. I purchased a great book by Mary Anderson et. al. called Applied Groundwater Modelling that I will go through as time allows. Hopefully by the end of all that I'll be able to get into the flopy and modflow documentation and examples and begin doing some small models for fictitious basins with simple uniform aquifer properties, recharge, and discharge. Then scale up one module at a time until I can use one of our aquifer studies.

00:44 UTC


Flood Modelling / Water Resource Management career Pathway

Hi fellow engineers, I hold a Ph.D. degree in Civil Eng (Water Sensitive Urban Design topics) & a Bachelor's degree in Civil Engineering and am seeking a job very soon.

I've been living in Melbourne (Australia) for a few years so it's not an option to move out of the town for a job.

During my Ph.D., I gained fundamental knowledge in WSUD (though not too much modeling experience), but I talked to someone in the field who did flood modeling for 5~7 years who recommended that flood modeling might be a better job option than water resource engineer.

I'm also pretty much interested in broader property development topics, so I guess my career can also be easily directed to a subdivision-ish job. I had no working experience in town, so I'd like to hear from you guys on the career path to up-play this PhD degree.

Would appreciate it if insights could be given, including how the next 5~10 years would look like in the job & future opportunities on the way.

Sincerely, Reddit user.

12:48 UTC


Hi, I am by no means a hydrologist (I'm a computer programmer) but I would like to ask a question. I am working on a planet terraforming simulation, and I would like to make it as scientifically accurate as practical. How would water behave on a barren planet (please see details)?

Suppose a planet similar to Earth had no water. A very dry athmosphere that did contain hydrogen and oxygen, but for some reason I can easily make up (this is sci-fi) they don't mix, until some event makes it finally start raining Starting from 0 water on the planet, with no plants to absorb water from the soil and so forth...

How would you expect water to act in these conditions? This is a rocky surface not yet made into soil. More specifically: How much would such a surface absorb? what would the evaporation rate be like (assuming conditions are otherwise like Earth's)? how much would end up into lakes? how fast would erosion start changing these things?

Any help tackling these questions would be appreciated.

Please keep it in laymen's terms, although I am familiar with mathematics, so formulas are very welcome.

01:22 UTC


Shields Curve plot

This is probably a long shot, but I'm hoping to plot some of my calculated tau c against the Shields Curve for incipient motion. Does anyone have a plot for this? Or the data to make one? I'm specifically working in R, but I can also plot this in excel if needed...

20:07 UTC


Data Questions: Precip and Streamflow

Hi all, not sure if this is the right place to post this but I'll give it a go. I was recently hired on as an analyst for a water resource protection agency. I'm going to be the new program lead for hydrologic/meteorologic monitoring as it relates to our target watershed (120,000 acres give or take). I come from a fish/stream ecology background, so there are some things I'll be learning by trial and error. I have a couple of logistics questions that I'm hoping someone might be able to help me with.

(1) My supervisor has tasked me with data collection and maintenance for our precipitation monitoring stations. He has specifically asked that I find a way to keep our precip gages from freezing. Does anyone have a suggestion as to how to do this? All I've been able to find are expensive heated precip units which I don't think would serve our purposes.

(2) I'm going to need to develop rating curves for our study tributaries which is ultimately not a problem; however, my supervisor wants to capture all events including high-flow storm events. Does anyone have suggestions for either safely collecting flow measurements in a high-velocity system using a flow meter or doctoring the rating curve to account for these events? My research has produced very little beyond vague SOPs.

Any help is appreciated!

18:16 UTC


ToC Calc Question.

In calculating the time of concentration, after calculating the sheet flow and shallow concentrated flow, we calculate the remaining sections of the longest flow path with mannings equation as cahnnelized flow. What do you guys use as the hydraulic radius (r) wiith no flow/depth data when the areas in question sees water. I've been doing what another hydrologist suggested and just use r=.5 conservatively. In TR-55 it recommends using the 2yr reoccurance interval. Looking for opinions from my fellow hydrologists. Thanks guys!

23:46 UTC


Hi! I’ve got a job on groundwater modeling, but I’m new to the field and know nothing about it.

I used to work in mechanical industry, but I changed career to groundwater modeling. I’m new to this field and I have to learn from scratch.

There’re so much knowledges and informations I need to know and it scares me. I hope to plan my learning path efficiently to be a competent modeler.

I know I’ve got a lot to learn, so I’ve done some research on the knowledge I need. If there’re any knowledge that I need other than this list. Please let me know.

  1. qgis

I think this will be the easiest to learn.

2.programming I’m learning Python now. I hope I will be able to write model codes in a year

3.hydrology Don’t know anything about it. I’m learning it on textbooks and videos

4.programming I’m learning Python now. I hope I will be able to write model codes in a year

5.modeling software I will be learning feflow first.

From my research, I think these will be the skills I need. What scares me the most is having to tweak equations and apply it in the models. I haven’t been studying very much and doesn’t have a strong mathematical/physics background.

If there’re any advices, learning platform please let me know. Thanks a lot.

14:49 UTC


Hydrology information

I am in grammar school in the Czech republic and I would llike to study hydrology and hydrogeology, but there are not much informations on what is like to work in hydrology. What is your typical day like? How high is your salary? Is it hard degree? How would you rate your job after school on scale 0-10? Can you travel in this job abroad? Do you work with people or alone? What qualities should good hydrologist have? Thanks for the information and sorry for my English, I am not a native speaker.

17:38 UTC


Advice on choosing a masters program for someone interested in a career in floor forecasting/risk assessment

There are three courses offered by TU DELFT that I am having troubles choosing from:

- Water resources engineering, courses:

  • Quality, Quantity and Design, Information and Advice
  • Water Quality and Principles of Environmental Engineering
  • Design and Modeling of Urban Water Infrastructure Systems
  • River Basin Hydrology and Water Management
  • Water Treatment Technologies
  • Operation, Control, Management and Adoption of Urban Water Infrastructure Systems
  • Regional Hydrology
  • Water Resources Engineering and Management

- Hydraulic Engineering, courses:

  • Base: Hydraulic Engineering Fundamentals and Environments Part I
  • Hydraulic Engineering Fundamentals and Evironments Part II
  • Coastal Engineering
  • River Engineering
  • Advanced Design of Ports and Waterways Systems and Interventions

- Hydraulic and Offshore structures, courses:

  • Base: Hydraulic and Offshore Structures
  • Hydraulic Structures
  • Offshore Structures
  • Marine Renewables
  • Dams, Dikes and Breakwaters
  • Floating and Submerged Structures

Reason I am confused is because they all have aspects relevant to the topic of flood management. Maybe because I still have a shallow idea on the topic but going through the courses materials just made me more confused rather than anything. Any advice would be greatly appreciated!

Edit to add info on courses

12:16 UTC


[Advice] what types of projects or training would you recommend for an early-career hydrologist?

Hi everyone,

I’m 8 months into my first hydrology job working for state government in the US and I’m looking for recommendations on what types of trainings or projects you think would be most beneficial for long term career success.

Currently, I’ve been learning how to take water level measurements in some of our wells and analyzing that data, updating our hydrology website as part of a multi-year series of meetings I attend relating to drought, learning GIS and R for creating maps for presentations and analyzing water demand data. I will hopefully be learning how to perform geophysical logging soon as well.

I love my job and have no plans to leave for several years, however, the pay is low and I’ve heard that working at the Federal level is more lucrative than state, and I’ve heard that geophysical logging is very useful to private well drilling companies.

What do you suggest?


14:01 UTC


HECRAS 6.4.1 Reference Manual: Calculating the Cell Velocity from Faces Normal Velocities.

Hello I am attaching screen capture from HECRAS Reference Manual 6.4.1.

Calculating cell center velocity based on normal velocities

Does anyone know how are the weights (w_k) calculated? This is supposed to be understood from Perot (2000) article titled: " Conservation Properties of Unstructured Staggered Mesh Schemes". However I didn't manage to understand what is w_k.

12:09 UTC


Textbook recommendations

What is a good reference book to study hydrology?

I want it to cover (hydrologic cycle, water vapor dynamics, soil-water dynamics and infiltration, catchment storage, hydrograph analysis, flood routing, design storm, probable maximum precipitation and flood frequency analysis....)

11:46 UTC


Boundary condition lines for 2d flow areas

Hey, I'm new to hec-ras and I'm having trouble setting up boundary conditions.

I want internal boundaries and I've placed then inside my 2dflow mesh but they are still external boundaries. How do I change this??

1 Comment
04:42 UTC


MATLAB Automated Theis Curve Matching

Hi friends, this is for a school project. I wanted to create a code that would automatically tell me the Storativity and Transmissivity using Theis's equation given drawdown, time and radius data. I'm using Monte Carlo methods to estimate S and T within a certain tolerance level. I'm getting accurate numbers for transmissivity but my storativity is three decimal points off what other models are showing me. Apologizes if this is the wrong subreddit for this!

data1 = xlsread('TestPumpingData.xlsx'); %Change to the excel sheet of whatever data you would like to test
drawdown = data1(:, 2); %assuming drawdown is in the second column
r = ones(length(data1), 1) * 60; %Change what this is multplied by to change the radius
time = data1(:, 1); %MINUTES
Q = 2500; %Change the pumping rate
num_iterations = 1e7; %how many times you would like the code to run
tolerance = 0.025; %Accuracy, will cause the code to not work if too small
CalculatedDrawdown= 0; %initalizing
for i= 1:num_iterations;
u = (((r.^2).*S)./(4.*T.*time));
CalculatedDrawdown = (Q./(4*pi.*T)).*Wellfunction(u);

if abs(drawdown-CalculatedDrawdown)<= tolerance;
S= 0.00000001 + (1 - 0.00000001) * rand;
T= 0.00000001 + (10000 - 0.00000001) * rand;
loglog(time, drawdown, '-o', 'DisplayName', 'Drawdown');
hold on;
loglog(time, CalculatedDrawdown, 'DisplayName', 'Calculated Drawdown');
ylabel('Drawdown/Calculated Drawdown');
title('Log-Log Plot of Drawdown vs. Time');
grid on;
StorativityFactor= (S/1440); %Converts measurement from minutes to days, no need to do this with Transmissivity
function results=Wellfunction(u)
results= -0.5772-log(u)+u-((u.^2)/4);

EDIT: I figured out why I was getting the wrong storativity and suprise suprise it was units... oops! I have time in minutes, and so to get the right storativity if your data is in minutes divide it by 1440 at the end.

20:01 UTC


Flood Mapping program

Hi there, I’m a Landscape Masterplanner/Designer by profession. I deal with a lot water-adjacent masterplanning and landscape projects (rivers/coasts/stormwater) and usually approach designs to be more resilient via detailed flood mapping analysis works received externally via a hydrologist/other engineer, or something much more simplified and juvenile in comparison generated by myself (GIS/3D software)

I wanted to do the leap into learning more detailed 1D/2D(potentially 3D) flood analysis mapping and wanted to ask what software you recommend?

I want to truly expand and dive deep into flood mapping analysis works as I already work intensively in climate adaptive design and designing for water resiliency, it only makes sense to bridge the gap. I understand this a commitment that can be several years in the making, luckily work for a company that can pay for licenses and training if required, but I’m unsure of where to jump onto.

HEC-RAS or TuFlow perhaps? To note, I do work with ArcGIS Pro/AutoCAD etc as well, so integration would be great.

Thank you for any answers, it is much appreciated!

10:53 UTC


Advice on resources for ICM InfraWorks and how to gain the knowledge to use it in the first place

Hello hydrology experts, so I recently graduated in civil engineering and am interested in pursuing a career in flood risk assessments/stormwater management. Where I am, ICM Infraworks and HEC-HMS/ HEC-RAS are really popular in the field but I wanna focus on ICM. So I'm here to first ask resources on how to learn this software.

Second thing , which maybe even more important, is how to gain knowledge to know how to use this software. Now I had to use HEC-HMS for my thesis project, and what was even more painful than learnign the software was that I had not enough knowledge in hydrology/hydraulics to even understand what I was doing. I couldn't understand my process nor my results, yes it was a mess. So I want to know if you have any crash course sort of thing that would supplement me with knowledge that would assist me in my ICM journey, a book, youtube channel, or an actual course.

I'd appreciate any advice, thank you!

11:50 UTC


Civil engineering student trying to decide between water/wastewater treatment vs. hydrology

I'm a final year civil engineering student from Canada trying to decide between water/wastewater treatment vs hydrology/river engineering.

I've done 2 internships in water/wastewater (design & field), 1 internship in hydrology (modeling), and 1 involving both in Asia. My internship in Asia invovled designing constructed wetlands, river pollution treatment (in situ), and redesigning river channels. That was my dream job in terms of what I did, but the work culture and salary there was unacceptable. I wouldn't want to work there long term.

Honestly, I would like to work a job involving both fields, but there doesn't seem to be any here in North America. So it looks like I need to choose one or the other despite my interest in both fields.

Can you convince me why I should choose hydrology over water/wastewater treatment ? Or, can you suggest a field that involves both that I should look into?

05:31 UTC


Looking for advice: applying to masters, missing pre-reqs.

Hey, people of r/Hydrology,

This is going to be a long-winded post looking for advice so leaving this warning at the top.

I recently graduated undergrad in Environmental Geosciences from a public university. Taking some courses in my electives focusing on Hydrogeology and Geochemistry. In my last year of undergrad, I did research in a geochemistry lab, I worked as an assistant at my state's land grant cooperative extension. Studying nitrate pollution from groundwater and surface water interactions. Now, I'm about to start a full-time gig as a geologist at a consulting firm.

I hope to go to grad school and eventually work for local/state/federal gov't in water resources. I'm a little wary of starting for a private firm. I'm interested in Hydrology, especially groundwater, hydrologic modeling, and groundwater contamination and scarcity. But I'm struggling to hone in on a topic. My experience in geochem research made me realize how much I dislike lab work. I enjoy fieldwork, and I am super interested in computational and data analysis work I've been exposed to in class in R & GIS groundwater modeling, and geochemical modeling.

When I look at grad programs, I notice they often require a lot of math, up to differential equations. My undergrad program didn't cover much math beyond Calculus 1, so I'm concerned about my readiness.

I feel like my problem is twofold: I'm not sure if I'd be a strong candidate for grad school without making up these deficiencies and if should I be taking the time working to save up and maybe take classes at a community college to make up some prereqs.

I feel lost in what steps I should take, and if anyone can give me some advice, I'd really really appreciate it!!

22:44 UTC


Hybrid Modelling in Hydrology

Hello everyone, I will like to make a request to this group for assistance. I am an hydrologist and new to hybrid Modelling and I want to develop a hybrid model(Process-based and data-driven). Does anyone know a particular platform that can help me get started or guide me through it. Thank you very much.

05:15 UTC


Sediment transport modeling cross sections

For 1D sediment modeling, how many cross sections should there be on the river for sediment transport purposes?

18:28 UTC


HEC-RAS 2D abnormal flow depths

I'm trying to get my HEC-RAS model to have flow depths that match my measured flows however I keep getting numbers that are off by a significant order of magnitude. What is the most common cause for this type of error and how do I fix it?

04:03 UTC


USBR Water Supply Competition

This came along my LinkedIn scroll today and I thought it was pretty interesting: USBR Water Supply Competition. Has anyone ever heard of this contest? Or entered a similar one since they seem to occur annually?

01:35 UTC


Question regarding HEC-HMS to RAS.

How do you guys input/implement the results of hec-hms to hec-ras. I only have the IDF curve for my watershed and no streamflows. I've read that some do a hms to ras methodology by setting a very little subbasin area in hec-hms then the flow at the junctions would be the flow hydrograph input in hec-ras. Is this a valid considerations or methodology? What do you guys usually use?

14:25 UTC


How does HECRAS process the input terrain?

I provide HECRAS with a raster terrain which if inserted into QGIS would appear to be a stepped regular square grid (RSG):

Screenshot from QGIS of some area in the terrain

when I insert such terrain into HECRAS, If i take a screen shot in RASMapper I get the following terrain:

Screenshot from QGIS of some area in the terrain

Obviously, HECRAS processed the terrain. I have two questions:

  1. Does HECRAS use the new representation of the terrain in the computations or does it rely on the stepped version?
  2. what is the technique used for the conversion. I found in the literature the following:

TIN, stepped RSG and triangulated RSG (De Floriani and Magillo 2003)

Most probably the technique used in HECRAS is close to the right technique: triangulated RSG but not identical, since this method doesn't explain the pyramid like shapes produced in HECRAS.

1 Comment
10:58 UTC


I have a Hydrology joke

But it has run off

19:23 UTC


HECRAS 6.0: Extracting Hydraulics Property Tables or Values throughout simulation

Hey :)I'm using HECRAS 6.0 and I want to extract the hydraulics properties used when solving the diffusion wave approximation. I need:

  • The cell water volume for each t (time index)
  • Face wetted area for each t
  • Face wet perimeter for each t

I found the cell water volume from the HDF file under a key named 'Cell Volume'. For the wetted area, I didn't find a matching output from HDF but thought that I can obtain it by dividing the 'Face Flow' output by the the 'Face Velocity' output (hoping I'm understanding the face flow correctly).

However, I'm not managing to find the wet perimeter. In RASMapper I have access to all property tables: Cell volume, face wet area and face wet perimeter as a function of water surface elevation. However, these tables (calculated by processing the geometry) are stored in a file .C# (where # denotes the number of the plan), which I don't know how to open.

Two questions:

  1. How can I obtain the wetted perimeter as a function of water surface elevation for each face in the study area

  2. Did anyone manage to open these property tables created by the geometry processor (even before running a simulation)?

Thank you :)

15:30 UTC


HEC HMS Error Message Help

Hello all, I'm using HEC-HMS 4.10 version right now and I keep getting this error message:

Warning 15303: Aborted run "2 yr" at time 19Oct2023, 10:48:36

I think it has to do with HEC-HMS messing up with control specifications dates but I don't know for sure.

Any comment or advice would be very much appreciated! Thank you so much!

16:10 UTC


Sediment Budget Analysis

Hi! We're trying to quantify sediment yield of a certain subwatershed in the Philippines using SWAT. Unfortunately, we're fairly new with the process and I would love to hear some insights and references from you guys. We'll be needing this for river management in the area. Thank you very much!

1 Comment
05:18 UTC

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