地下河流/小溪流动枯竭时在表面吗?- 江南体育网页版- - - - -地球科学堆江南电子竞技平台栈交换 最近30从www.hoelymoley.com 2023 - 07 - 08 - t21:03:23z //www.hoelymoley.com/feeds/question/5148 https://creativecommons.org/licenses/by-sa/4.0/rdf //www.hoelymoley.com/q/5148 13 地下河流/小溪流动枯竭时在表面吗? reddit //www.hoelymoley.com/users/3087 2015 - 07 - 07 - t05:44:58z 2015 - 07 - 13 - t14:18:28z < p >在我当地有一条小溪,在夏天完全枯竭,流动强烈在冬天。的情况,在小溪的位置枯竭,它继续流动的地下?< / p > < p >如果是采取相同的轨迹溪吗?在典型的深处开始流动的“转发”吗? < / p > //www.hoelymoley.com/questions/5148/-/5150 # 5150 11 答案为河流/ user2821小溪流动的地下枯竭时在表面吗? user2821 //www.hoelymoley.com/users/2536 2015 - 07 - 07 - t13:25:45z 2015 - 07 - 13 - t14:18:28z < p >水液态总是最快的路线降低高度。雨水会流垂直到地下水表面如果不是渗透率是< a href = " https://en.wikipedia.org/wiki/Darcy%27s_law " rel = " noreferrer " > < / >有限的< a href = " http://all-geo.org/highlyallochthonous/2011/01/geology-is-destiny-globally-mapping-permeability-by-rock-type/ " rel = " noreferrer " > < / >材料属性。< / p > < p >渗透率控制水速度< a href = " https://en.wikipedia.org/wiki/Surface_runoff " rel = " noreferrer " > < / >渗透和渗透材料。例如,地表径流水量的硬路涂料,当水从一个喷壶进入花坛的软土。砾石、砂和破碎岩石渗透率高的页岩和non-fractured火成岩低渗透。如此之低,这在许多情况下,似乎是完全令人费解的人类时间尺度。< / p > < p >河流也是一样。如果河流透水岩石,典型的沉积物沉积在河边本身< em > < / em >(见图),地下水也会流入河床下的沉积物,允许水仍然是进入上游。< / p > < p >一个更好的方法来了解河流或湖泊在这种背景下,是它的表面表现< A href = " https://en.wikipedia.org/wiki/Water_table " rel = " noreferrer " > < / >地下水表。如果你挖一个好身体旁边的水你会达到地下水与河水表面相同的高度。 The gradient of the groundwater surface and the permeability of the material controls the direction and velocity of the flow.

However, if more water enters a system than the surface can infiltrate, the surplus will flow as surface runoff, typical for wadis (See picture) in desert areas.

Wadi. Photograph taken by Mark A. Wilson, The College of Wooster

So, to answer your question. It depends on the local geology, but ground water will always flow from the precipitation area to the oceans (or a lower point where it can evaporate or being pumped up). Ground water exists everywhere and the gradient of the hydrostatic pressure controls the direction of the flow. As viable rivers shows the ground water table, it is usually rather safe to assume that the ground water under the dry river flows more or less the same direction.

However, ground water flow can be changed by e.g. pumping from irrigation wells. Imagine a flat lying river bed with a well upstream. When enough water is removed from the well and eventually evaporated, ground water will flow towards the well. The water don't 'remember', but follows the law of gravity.

//www.hoelymoley.com/questions/5148/-/5156 # 5156 9 答案为河流/ haresfur小溪流动的地下枯竭时在表面吗? haresfur //www.hoelymoley.com/users/1242 2015 - 07 - 10 - t02:21:21z 2015 - 07 - 10 - t02:21:21z < p >要回答这个问题,我先备份,谈论发生了什么雨,流流然后会发生什么当溪流干涸。< / p >

When it rains, some of the rain hits the ground or trees/plants and is evaporated before it flows away from where it hits and before it sinks into the soil very far. Some enters the soil but is taken up by plant roots and transpires back into the atmosphere. We don't need to worry about those components for this question.

Some of the rain flows down the ground surface, more or less as sheet flow and eventually merges into little flow paths to the creek or river. That's called runoff.

Typically, some rain will enter the ground and flow down to the water table, which is the surface of the saturated groundwater. By that I mean permanent water in the subsurface where all the void spaces in the rock or sediment are completely filled with water (there are some different definitions of groundwater that include the unsaturated zone but I'll keep them separate). Groundwater flows downgradient under gravity towards a stream, river, lake, or the coast.

In between there is sort of a fuzzy situation where water flows in the unsaturated soils, moving downward and or sideways until it concentrates in a perched aquifer or a seepage face at the stream. That water will discharge to the surface water system. Importantly, it typically reaches the surface water more quickly than the groundwater flow but slower than the runoff. Its often called quickflow, interflow, or perched flow. Let's not worry about this too much - you can think of it as slow runoff or fast groundwater that kind of smears out the streamflow peaks.

Streamflow, then, is mostly made up of these 3 components. Why do streams flow between rain storms? It does take runoff some time to reach the stream and flow downstream so it doesn't stop instantly but it goes away the fastest of the three. Quickflow will keep going a bit longer and depends a lot on the geology, soils, and topography. Simplistically, it will keep streams flowing longer than pure runoff would. Saturated groundwater is a slower process in terms of its discharge to a stream and, particularly for big rivers can keep them flowing year round. The first take-away message is the groundwater and surface water are interconnected - at least in the big picture.

A couple of interesting things can happen to the groundwater-surface water connection. First, there might not be enough groundwater flow to keep it discharging to a stream, either seasonally like your creek or permanently in some places. If the stream still has water it can reverse the connection and lose water to the groundwater - a losing stream instead of a gaining stream. Without more rain or flow from upslope the stream will dry up. In some cases the groundwater level can drop faster than the stream drains into the sediments and the system can become disconnected. The groundwater flow direction shifts so it is not towards the stream but towards a more regional discharge location. Since streams also flow down to the regional surface water system, the groundwater will often take a similar path but overall I don't think of it as an underground stream.

Finally though, things aren't always that straight-forward. One thing that often happens is that valleys fill up with sediments that are more permeable than surrounding sediments or rock formations and allow more flow. In that case the groundwater flow is mostly along the stream flow direction in the valleys and stream bed. It then looks similar to an underground river. That can happen when the river or creek is flowing or when it stops. The fancy word for it when the river is flowing (particularly when you are talking about pretty local scale effects) is hyporheic flow - meaning flow below the river.

So that's probably more than you wanted to know, but for your creek it might go each year from pretty much all runoff, to gaining groundwater, to losing to the groundwater, to disconnected, to dry with some subsurface flow through the stream bed to more overall groundwater flow that doesn't see any influence from the stream location. But it depends on the weather, the sediments, how steep the land surface is, and perhaps some other complicating factors.

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