What is low water in hydrology? Features, types and criteria for determining the intergalactic

About such concepts as flood and high water, many of you have heard. But not everything is known about what a low-water day is. This is one of the phases of the water regime of the river, which will be discussed in our article.

The regime of the river and its main phases

There are several million rivers and streams in the world. And each of them is unique in its own way! Each river has its own "character" and its own regime. Under the regime of the river means a complex of all seasonal changes in the state of the watercourse, which are due to the physico-geographical conditions of its basin (primarily the climate of the territory).

Seasonal climate changes are reflected in the state of almost all the rivers of the Earth. On some - stronger, on others - less noticeable.

In the summer, when high temperatures are set in temperate latitudes, water from the earth's surface evaporates actively. Accordingly, all the rivers in these latitudes gradually become shallow, algae begin to actively propagate in them, coloring their channels in a bright green color. In the early spring, on the contrary, the rivers become deep-watered. First of all, due to the melting of ice in the riverbed and snow within its catchments.

The regime of any river includes three main phases. It:

1. Flood (the highest level of water in the river).
2. Flooding (a sharp and short-term rise in the water level in the river, provoked by heavy rainfall).
3. Mezhen.

What is a low-water? In geography, this is one of the phases of the watercourse regime. More details about the features of this phase will be discussed later.

What is the meadow: the definition and essence of the concept

So, we found out that each of the rivers has its own water regime. Now let's figure out what is the low water, what features are characteristic for this phase of the river regime.

Mezhen - this is the lowest level of water in the river, as well as a relatively long period of time at which this level is maintained. As a rule, this period is not less than 10 days. At this time, the river feeds mainly by groundwater.

In temperate, as well as high latitudes of the Northern Hemisphere, the lowland begins at the end of summer or in autumn (less often in winter) and continues until the freeze-up begins. On mountain rivers it can temporarily be interrupted by powerful floods, caused by heavy rainfall.

In order to better understand what is the middle of the river, it is necessary to find out from which factors it depends. These factors include:

• Geographical location of the basin;
• Climatic features of the region in which the catchment area is located;
• Terrain relief;
• Geological structure of the territory;
• Vegetation prevailing within the river catchment area;
• The degree of anthropogenic influence of man.

In general, the low water is a rather volatile, variable phase of the water regime, which is explained by the "fragility" of the river system itself. Even the most insignificant impact can significantly change the nature and duration of the river mezhdeni.

What is the meadow: the meaning and origin of the word

Why does water in the riverbed suddenly become smaller? The answer is simple: it occurs as a result of the restriction (or complete cessation) of the supply of a watercourse from a particular source. In the arid regions of the planet, the riverbed during the intergrade may dry up altogether. And sometimes it even has time to cover with scarce vegetation.

What is the meadow from a philological point of view?

The origin of this scientific term is most likely connected with the word "interstitial". This is the boundary between something. In this particular case we are talking about the boundary between the seasons of the year. Probably, in the olden days segregated precisely based on the water level in local rivers.

Types of river mezhdeni

Mezhen can be different. Depending on the weather conditions of the terrain, hydrologists distinguish:

• Summer (or summer-autumn);
• Winter low-water season.

Summer-autumn low water begins immediately after the spring high water (in July-August) and continues until the period of autumn floods. If the latter are not observed, then this phase can continue throughout the winter, until the next spring high water (winter low).

Depending on the time criterion, the river low water can happen:

• Short-term (lasts from 10 to 30 days);
• Long (lasts more than 30 days).

But in most cases, the low water is broken in time, intermittent.

Criteria for determining the intergalactic

It should be noted right away that the separation of the meadow (like any other phase in the river's water regime) is rather subjective. Especially when it comes to its time frame. That is, it is not possible to determine concretely and unambiguously when the onset of the low water begins on a particular river.

The main criterion for determining mezhdeni is considered to be a change in the volume of runoff in the riverbed. So, if at some period this indicator does not exceed 10-15% of the total annual flow, then we can talk about intergeneration in this particular period of time. An interesting fact: on large-scale topographic maps, the contours of river beds are depicted precisely according to their state in the period of intergeneration.

For the majority of Russian rivers and streams, the summer-autumn low water (from August to November) is characteristic. Summer showers on the territory of Russia, as a rule, are short-lived and can not significantly affect river floods. Exceptions are only the mountainous regions of the country, as well as the Far Eastern region, where on the rivers the low water can not be observed at all.