# Questions tagged [hydrology]

Hydrology is the study of the properties and behaviour of water. It concerns both surface as well as subsurface water, although water in the oceans and atmosphere is generally excluded. Those are studied by oceanography and meteorology, respectively.

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### How to check the recurrence intervall of heavy rain events

Heavy rain or flood events have recurrence intervalls. I.e. 100 year, 50 year or 25 year events. However, with increasing data and global warming and other factors these intervalls change. How can I ...
4k views

### How do oases form in the middle of the desert?

I am wondering if there are any theories about the formation of oases, and I am also curious about why an oasis can even last for a very long period of time. I have heard that fresh water exists on ...
17 views

### what is a sensitivity analysis in heavy rain 2D surface / 1D drainage network models

For my thesis, the lecturer proposed to make a "sensitivity analysis" with a 2D surface model connected with a 1D drainage Network model for a storm rain event. However, I'm having problems to figure ...
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### formula to convert precipitation in mm/h to runoff in m³/s

I have precipitation data in mm/h but to use them for my model I need them in m³/s. Is there a formula to convert them?
21 views

### Modelling extreme rainfall events: 'blanket approches' when considering soil infiltration

For my thesis on modelling an extreme rainfall event with a 2D surface runoff model I'm supposed to consider the effect of soil infiltration on the runoff: In my work description it says I'm supposed ...
3k views

### Do dams reduce the flow of river downstream?

There is a conflict between Egypt and Ethiopia, because the latter wants to build a dam on the Nile river. Citing this article: [Egypt] fears the Nile dam will reduce its share of the river and ...
94 views

### Loop in the continental divide

Various maps of the Continental Divide (the hydrological feature, not the trail) contain a loop that looks like this: What is the hydrologic meaning of the loop in Wyoming? Even if it's a basin, ...
18 views

### Avra valley aquifier region boundary

Attached is an image of the Avra valley in Southern Arizona, USA from Effects of Kriging and Inverse Modelling on Conditional Simulation of the Avra Valley Aquifier in Southern Arizona -- Clifton and ...
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### How are aquifers found and traced?

Recently a line from a news article about an aquifer in the path of a tunnel boring machine for Metro networks caught my attention: Ahead of tunnelling, the builders conduct hydrogeology, a study ...
38 views

### Run Hydrus-1D from the command line

Hydrus-1D, is a modeling environment for analysis of water flow and solute transport in variably saturated porous media. This program has a graphical environment which works very well, however a lot ...
38 views

### What does a “closed basin” mean in groundwater terms?

This answer talks about a "closed basin" that has an outflow to the sea. I had previously assumed that "closed basin" meant the same as "endorheic basin", but that is obviously not the case. What is ...
45 views

### How to recharge ground water directly from river water

I am not sure if I am asking it on a correct platform or not. A rainy river passes through my village. We suffer both in summer and in rainy seasons due to this. Could anyone explain how to recharge ...
85 views

### Code for DEM based flow routing in R

I have a DEM as shown for which I have determined flow paths using D8 algorithm (My own code) in R. The resulting DEM with the flow paths is also shown. The flow paths are generated in the form of ...
71 views

### Can I interpolate rainfall data from stations outside of watershed for the watershed?

I have only few station inside the watershed so I want to use the stations outside if I can to get better results
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### Flood and Statistics

A recent flood was due to combined effect of rainfall(precipitation) and reservoir storage. I have daily rainfall data and reservoir storage data. How can I correlate these two to get a statistical ...
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### Hydrology- flow accumulation

I'm not specialist in hydrology, and I would be very grateful if you answer my question: What is flow accumulation in hydrology? Why algorithms used to calculate it over a raster DEM don't take ...
79 views

### What effect does concretization (paving/flooring with concrete) has on ground water table

I am a newbie for hydrology. If the question seems to have "well known answer", I appreciate if you point me to the resources. I will add details to the question based on comments. Consider a town of ...
42 views

### What would be a reasonable set of thresholds for flood severity classes?

When working with extreme hydro-meteorological events, flood in particular, it is common procedure to classify each event by its return period/recurrence interval. This probabilistic measure has the ...
98 views

### Is there an approximate rate for water temperature by depth that could be modeled simply?

I know that there are a couple of questions covering latitude and longitude for water temperature, but overall I'm more interested in the rate of temperature change by depth. Thought Process: ...
3k views

### How is it possible to use up the water in a region?

The Dead Sea, rivers in California and the Aral Sea are said to be shrinking due to water usage, e.g. for agriculture. Yet the water must go somewhere. After the fields are irrigated, the water ...
59 views

### In winter, is pond water warmer with or without a fountain? I have goldfish [closed]

I know that goldfish can hibernate but I'd like to keep the water warmer for them. Is moving water colder or warmer than still water? The water shoots out of "pipes" about 3" above the water's ...
389 views

### Are the water year/hydrological year different around the world?

Following the commonly-known USGS definition of Water Year (or Hydrological Year) we know that it starts on the 1st October and ends on the next 30th September. Is this definition valid only for ...
62 views

### When will the weight of melted polar ice release the (currently stuck) subduction of the oceanic plate West of the Oregon coast?

Melted polar ice water makes the oceans deeper on average. The extra water on top of the oceanic plates makes them sink relative to the continental plates. This relative vertical displacement will ...
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### How to obtain the correlation between monthly streamflows based on physical concepts?

I've been tasked with generating synthetic streamflow scenarios through disaggregation. First, I will generate 50 years of streamflow data. For that, I will probably use a simple model as AR(1) or an ...
31 views

### Environmenal flow in the context of global gridded hydrological analyses

Environmental flow (EF) is a widely used concept in river basin management and river ecology. There are more than 200 methods to estimate the flow that should be left to the rivers to ensure a ...
481 views

### Why do we consider hydrostatic pressure and lithostatic pressure separately?

In petroleum geology, why do we consider hydrostatic pressure and lithostatic pressure separately? Surely the pressure at any point, whether fluid or rock, at depth is simply equal the weight of all ...
44 views

### Do desalination plants affect the ground water table?

I saw an article recently in the newspaper stating that a desalination plant near the seashore was causing the ground water to become saline. Usually I would expect that areas where saline water ...
22 views

### What's the difference between “loading” and “receiving” in water quality modeling?

I see some models described as simulating 'receiving water quality' and others as 'pollutant loading' models. What is the difference between loading and receiving models in this context? I am more ...
557 views

### Rivers - How to calculate maximum velocity from average velocity in a cross section

I'm studying flow velocities in a small river. I have a lot of data of average flow velocities in cross sections throughout the entire catchment. And I know the river develop a stream velocity profile ...
86 views

### Rocks sparking under water

I have searched for an answer to this question for years, to verify if it was true. A man that lived on a river in the rugged part of the northern Washington Cascades told me an interesting story. He ...
79 views

### How did the Rhine originally look like? (before human intervention)

For personal reasons I decided to examine the shape and formation of the Rhine. Unfortunately though, the Rhine has long been diverted from its original course by human intervention, so I tried to ...
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### Does the configuration of a confined layer change the storage?

I have a confined aquifer of sand. I will temporarily drain the aquifer, remove the top one meter of the aquifer and then replace that with a layer of gravel. After that I will restore the layer (and ...
224 views

### Lake outflow forming a “reverse delta”?

While rivers often form a delta when they flow into a lake, the outflow of a lake is usually a single stream. Are there lakes where the water flows off in multiple channels that merge into a single ...
117 views

### Is it possible to create clouds by pumping water into volcanoes?

Suddenly, there is this idea in my mind that if an important effect of global warming is rainfall reduction and drought, is it possible to use volcanoes as water vaporizers (regardless of costs)?
127 views

### Searching for ground water

I would like to attempt to build a well-type structure in a woodland area. This woodland is mainly inhabited with Silver Birch and Sycamores and there is a shallow stream running down off of a ...
149 views

### Comparing Pros and Cons of SWAT and HSPF

To model hydrology in a watershed, two of the most famous and widely used distributed models are SWAT and HSPF. I have some good understanding of HPSF, but I don't know when and why should one prefer ...
104 views

### Hydrology - Flowrate vs. radius of influence

I am using the following equation (Theim/Dupuit) to determine radius of influence for an unconfined aquifer. Assume all other variables are held constant. If Q increases, does the Radius of ...
169 views

### Clarification of overbank flows

Apologies for what may be a very basic question, but I am struggling to understand the definition of overbank flow. Overbank flow is defined along the lines of this: Water flow over the top of the ...
83 views

### how to know the correct results in watershed delineation in ArcGIS?

When I use one DEM in my study area to delineate watersheds, the results are different from when I mosaic 4 DEM layers adjacent to each other. After the mosaic process, 3 of the basins were merged in ...
117 views

### What's the difference between these most basic, first-order models for estimating runoff?

There are a lot of variations of basic, first-order hydrology models to estimate runoff from rainfall with a few other parameters. From what I can tell, most very basic rainfall-runoff models use one ...
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### Does nitrate take a particular long time to percolate from surface into groundwater?

In a recent discussion with a farmer, the (at least in northwestern Germany) "popular" topic of nitrate infiltration into groundwater came up. The general view is that lots of fields receive more ...
714 views

### Rivers flowing into Pakistan

Why do Rivers flowing into Pakistan come from either Afghanistan or India and not from inland mountains? Is it possible for Pakistan to source fresh water from its northern mountains avoiding India ...
501 views

### Concept of artesian aquifers and pressure is not clear.

I do not understand how the Artesian aquifer is causing the water in the flowing well to reach a level higher than the ground surface? And what role does the piezometric surface play in it?
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### Who would know how to manage rainwater erosion on a sloped property?

I'm a meteorologist with little experience in hydrology. I'm studying my land with the rainwater flow patterns during heavy rain events and looking to manage the erosion, flash flooding, and ponding ...
4k views

### If water is a renewable resource, why is there water scarcity?

Water is a renewable resource, renewed by the water cycle. If we use water too quickly, water should get evaporated and come down again as precipitation. So, Why is there water scarcity if water ...
224 views

### Is there a special name for along-course elevation profiles of rivers, and where you can you find them?

Was discussing the terrain and rivers of Europe today with my father and it became apparent that a graph of the elevation versus course of a river would offer interesting insight, including a quick ...
62 views

### Looking for a reference for identifing stream regimes(Intermittent, Perennial)

I'm a hydrologist with a good background in GIS. I'm looking for a reference (Methodology, Technical guide) for identification of temporary, intermittent and perennial streams. I google and only found ...
166 views

### How to relate RCM/GCM RCP climate projections to observational data for use in a hydrologic model

As a (smaller) part of my research, I want to look at climate projection data and how that might influence the hydrology within a study catchment in Rajasthan, India. For "the present day" climate, I ...