# Questions tagged [hydrology]

The study of the occurrence, distribution, movement, and properties of the waters of the earth an their relationship with the environment within each phase of the hydrologic cycle.

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### Is my basement flooding because the city floods a neighboring field to make an ice rink?

I bought a house about a year ago that was built in 1952, and the original house has French drains and a sump pump which keeps the basement dry. There is an extension, however, which was added at some ...
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### Computing the velocity of water under reverse flow conditions from storm water drain

I am trying to compute the approximate velocity of water during reverse flow from the outfall location to the street through storm inlets. This is generally seen during what is commonly referred to as ...
18 views

### HEC RAS and storm sewer

It is required to simulate the surface runoff in the city on the basis of the DEM and see how well the storm drains are coping. But I do not know how to make a water intake not from the edge of the ...
19 views

### How flood risk is determined

If you live in a 1% AEP flood zone, you have a 50.3% chance of being flooded in a typical lifetime (70 years), and a 15.6% chance of being flooded twice in this period. My Solution for 50.3% = 1 - exp(...
37 views

### Estimate cycle of the pump per day

I have a pump system that is on for 5 days. For the entire 5 days, there are 3 days that the pump system is able to complete on and off cycle. I want to estimate the cycle of the pump (on/off) per day?...
1 vote
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### Estimating circular pipe flow velocity through a known elevation profile and known length with a known initial pressure and flow velocity

I have a known elevation profile spanning the length of my pipe (~600 meters). An elevation value is given for every five meters of pipe. At the beginning of the pipe, I have a known velocity (1.1 m/s)...
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### Typical Runoff velocity values

I am computing runoff velocities for rainfall falling over an area using St-Venant 1D momentum equation. I wanted to have some idea if my computed velocities are within a reasonable range of what one ...
154 views

### Trinity Lake Leak

Why was Trinity Lake's control regulating discharge increased from 0 to 1,477 CFS on March 6 .. 20, 2023? (During historic drought in California.) What is "control regulating discharge"? It ...
47 views

### Can saline water be used in a hydro storage system and would the ambient temperature or higher liquid viscosity affect performance?

In regards to this question: How to determine the efficacy and potential energy of hydro power energy storage?. I'm searching for a cheap liquid that I can use for a small scale pumped hydro storage. ...
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### How can I eliminate oscillations in Sim-Routing for HydroCAD?

I am currently attempting to model a stormwater system that has a high likelihood of backflow because the proposed basins are interconnected and there are no intervening structures which would impede ...
143 views

### Why were so Many Older Bridges Built so Low to the Water?

Why were so many pre-1970 bridges built so low to the water that they do not even allow a single-level stand-up boat (serving as water buses or small fishing/research vessels) to pass underneath ...
1 vote
128 views

### How much energy is needed for the USA to only use desalinated water?

What amount of energy would it take to replace the entirety of America's water consumption with desalinated water? And how does it compare with the country's current energy generation capacity? By &...
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628 views

### Determining depth of flow in open channel flow

Open channel flow in a circular pipe has a maximum flow $Q_{max}$ at a flow depth approximately 93.8% of the pipe diameter. Calculating flow Q from depths 92.5% and 94.9% both give the same value for ...
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### How to cut a pipe such that water comes out evenly across the length?

I am trying to build a wetland filter for a pond. Basically, you dig a big hole, fill it with rocks (large at bottom, small at the top), and pump water deep under these rocks, so the water slowly ...
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### Is VLF-EM scanning for fractures a valid way to find groundwater for a well?

I need to choose where to drill an agricultural well. I am trying to get as much water as possible (at least 100 gpm). I am considering hiring a guy who claims to be able to find water using a device ...
122 views

### Why do dams deplete rivers?

I have often heard of cases where dams reduce the flow rate of rivers downstream. This makes sense in cases where some of the water that is captured by the dam is used for irrigation and such, but in ...
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### Why is the wet/dry boundary of ground not dangerous for foundations?

A building, such as a house, rests on a foundation. Beneath it is natural earth. When it rains, the ground around the foundation becomes wet. But the ground underneath the foundation does not. There ...
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1 vote
753 views

### Open Channel flow with pressure losses - flow depth?

In a horizontal channel that feeds off a river, does the head/pressure loss due to friction, turns etc in the channel translate to a drop in the water level between its inlet and outler? If so, could ...
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1 vote
48 views

### 2 mm accuracy in an affordable water level sensor (pressure transducer) - Does one exist? [closed]

I'm looking to conduct water level monitoring in streams and rivers for water resource engineering purposes. My plan is to use Arduinos and Raspberry Pis in conjunction with a pressure transducer, as ...
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351 views

### What is the technical name for a water reservoir that retains its contents via vacuum and ambient air pressure?

This is a strange question for me because this is so extremely common, but I have never heard a name to describe exactly what it is. This is commonly used to provide water to animals from a trough or ...
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### What is this structure in a park

It really has no informative signs on it just signs warning not climb or careful with your ball. It is in a Japanese park. I thought it is a water mound with its lots of pipes coming out it for ...
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1 vote
810 views

### Peak flow calculation using rainfall data

I am trying to use the Curve Number Method to calculate the peak flow over an area. The precipitation is provided in a table, with the first column being the time (hr), second column being the ...
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1 vote
911 views

### What is the difference (if any) in capacity factors and efficiency between reservoir hydropower and run-of-river power plants?

My question is about differences between reservoir-hydropower and run-of-river power plants. Are run-of-river plants less efficient? what would be an approximate guess of the differences? (assuming ...
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552 views

### Transporting water uphill at the highest efficiency possible?

I have a passing interest in water desalination projects. One of the challenges of desalination is simply moving the water from the ocean to the desalination plant. Typically the plant is built above ...
• 226
559 views

### Is there a method to determine the runoff for arid areas in developing countries?

Note: this question was totally rephrased and expanded on, addressing the comments and questions posed to the first version. The de-facto standard source for runoff calculations in South Africa is ...
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### How much air gap is required in a storm pipe?

I'm studying the design of storm sewers and I had two questions relating to air gaps in storm pipes: According to sources I've come across, flow through storm pipes require an air gap so as to ...
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### Terminology for ponding behind a bridge during a flood

I have read a specific term to describe the process when water pools behind a restriction such as a bridge during a flood. I cannot for the life of me remember what the word was. The term ...
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### Engineering in Kazakhstan and Rainfall Intensity

We are about to commence a large project in Astana, Kazakhstan worth several hundred million dollars. The design of Stormwater quantity, quality, and hydrology will be a large component of our works, ...
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### What is the purpose of these "steps" in rivers?

I have seen a number of structures within rivers, which resemble steps, and which allow the water to cascade down them instead of flowing naturally down the course of the river. Example 1: River ...
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### Differences between 2D hydrological modelling programs eg. HECRAS 5.0 (2D), TUFLOW, MIKE Flood

Just wondering what the difference is between 2D flood modelling programs. I am primarily considering whether HECRAS 5.0 (2D - currently in Beta) would be an acceptable alternative for simple 2D flood ...
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