Chukchi Sea organic world. Chukchi Sea - former Beringia
Let us determine the average long-term value (norm) of the annual flow of the Kolp River, Verkhniy Dvor point according to data from 1969 to 1978. (10 years).
The resulting rate in the form of average long-term water flow must be expressed through other characteristics of the flow: module, layer, volume and flow coefficient.
Calculate the average long-term runoff modulus using the relationship:
l/s km 2
Where F – catchment area, km 2 .
Runoff volume is the volume of water flowing from a catchment area over any period of time.
Let's calculate the average long-term runoff volume per year:
W 0 = Q 0 xT = 22.14. 31.54. 10 6 = 698.3 10 6 m 3
where T is the number of seconds in a year, equal to 31.54. 10 6
We calculate the average long-term runoff layer using the dependence:
220.98 mm/year
Average long-term runoff coefficient
where x 0 is the average long-term precipitation per year
The assessment of the representativeness (sufficiency) of a series of observations is determined by the value of the relative root-mean-square error of the average long-term value (norm) of annual runoff, calculated using the formula:
where C V is the coefficient of variability (variation) of annual runoff; the length of the series is considered sufficient to determine Q o if ε Q ≤10%. The value of the average long-term flow is called the flow rate.
Determination of the coefficient of variability Cv of annual runoff
The coefficient of variability C V characterizes the deviation of runoff for individual years from the runoff norm; it is equal to:
where σ Q – standard deviation annual expenses from the flow rate
If the runoff for individual years is expressed in the form of modular coefficients the coefficient of variation is determined by the formula
We compile a table for calculating the annual flow of the Kolp River, Verkhniy Dvor point (Table 1)
Table 1
Data for calculation WITH v
Let us determine the coefficient of variability C v of the annual runoff:
The relative root-mean-square error of the long-term average annual runoff of the Kolp River, Verkhniy Dvor point for the period from 1969 to 1978 (10 years) is equal to:
Relative root mean square error of the coefficient of variability WITH v when determined by the method of moments it is equal to:
Determination of the flow rate in case of insufficient observation data using the method of hydrological analogy
Fig. 1 Graph of the relationship between average annual runoff modules
the studied basin of the Kolp River, Verkhniy Dvor point and the analogue basin of the river. Obnora, s. Sharna.
According to the graph of the connection between the average annual runoff modules of the Kolp River, the Verkhniy Dvor point and the basin analogue of the river. Obnora, s. Sharna.M 0 =5.9 l/s km 2 (removed from the graph according to the value M 0a =7.9 l/s km 2)
Calculate the coefficient of annual runoff variability using the formula
C v – coefficient of runoff variability at the design site;
WITH V a – in the section of the analogue river;
M oa is the long-term average annual flow of the analogue river;
A– tangent of the slope of the connection graph.
Finally, to construct the curves we take Q o =18.64 m 3 /s, C V =0.336.
Construction of an analytical supply curve and checking its accuracy using an empirical supply curve
The asymmetry coefficient C s characterizes the asymmetry of the hydrological series and is determined by selection, based on the condition of the best correspondence of the analytical curve with the points of actual observations; for rivers located in flat conditions, when calculating the annual runoff, the best results are obtained by the relation C s = 2C V. Therefore, we accept for the Kolp River, Verkhniy Dvor point C s = 2C V=0.336 with subsequent verification.
The ordinates of the curve are determined depending on the coefficient C v using tables compiled by S. N. Kritsky and M. F. Menkel for C S = 2 C V .
Ordinates of the analytical curve of provision of average annual
water flow rates of the Kolp River, Verkhniy Dvor point
The probability of a hydrological quantity being exceeded is the probability of exceeding the considered value of a hydrological quantity among the totality of all its possible values.
We will arrange the modular coefficients of annual expenses in descending order (Table 3) and for each of them calculate its actual empirical provision using the formula:
where m – serial number member of the series;
n is the number of members of the series.
P m 1 =1/(10+1) 100= 9.1 P m 2 =2/(10+1)100= 18.2, etc.
Figure - Analytical supply curve
Plotting points with coordinates ( Pm ,Q m ) and averaging them by eye, we obtain the availability curve of the hydrological characteristic under consideration.
As can be seen, the plotted points lie very close to the analytical curve; from which it follows that the curve is constructed correctly and the ratio C S = 2 C V corresponds to reality.
Table 3
Data for constructing an empirical supply curve
Kolp River, Verkhniy Dvor point
Modular coefficients (K i)descending |
Actual security |
Years corresponding to K i |
|
Figure – Empirical security
In this article we will consider in detail the question of what the annual river flow is. We will also find out what affects this indicator, which determines the fullness of the river. Let's list the most significant rivers planets leading in annual drain.
River flow
The most important part of the planetary water cycle - this guarantee of life on Earth - are rivers. The movement of water in their networks occurs under the influence of a gravitational gradient, that is, due to the difference in heights of two points earth's surface. Water moves from a higher area to a lower area.
Fed by melting glaciers, precipitation, and groundwater Having reached the surface, rivers carry their waters to the mouth - usually to one of the seas.
They differ from each other both in the length, density and branching of the river network, and in the flow of water over a certain period of time - the amount of water that passes through a section or section of the river per unit of time. In this case, the key parameter will be the water flow at the river point at the confluence with the mouth, since the saturation or fullness of water changes upward from source to mouth.
The annual flow of a river in geography is an indicator, to determine which it is necessary to take into account the amount of water flowing per second from square meter the territory under consideration, as well as the ratio of water flow to the volume of precipitation.
Annual flow
So, the annual flow of a river is, first of all, the volume of water that the river throws out when it falls into its mouth. You can say it a little differently. The amount of water that passes over a given period of time through a cross-section of a river at its confluence is the annual flow of the river.
Determining this parameter helps to characterize the full flow of a particular river. Accordingly, the rivers with the highest annual flow will be the deepest. The unit of measurement of the latter is volume, expressed in cubic meters or cubic kilometers, per year.
Solid drain
When taking into account the amount of annual flow, it is necessary to take into account that the river does not carry pure, distilled water. River water contains both dissolved and suspended great amount solids. Some of them - in the form of insoluble particles - greatly affect the indicator of its transparency (turbidity).
Solids discharge is divided into two types:
- suspended - a suspension of relatively light particles;
- bottom - relatively heavy particles that are drawn by the current along the bottom to the place of confluence.
In addition, solid runoff consists of products of weathering, leaching, erosion, etc. of soils, soils, and rocks. The indicator of solid runoff can reach, depending on the fullness and turbidity of the river, tens and sometimes hundreds of millions of tons (for example, Yellow River - 1500, Indus - 450 million tons).
Climatic factors determining the annual river flow parameter
Climatic factors, which determine the annual flow of the river, are, first of all, annual quantity precipitation, catchment area river system and evaporation of water from the surface (mirror) of the river. The last factor directly depends on the quantity sunny days, average annual temperature, transparency of river water, as well as from other numerous factors. Important role the time period in which it falls also plays a role greatest number precipitation. If it is hotter, this will reduce the annual runoff, and vice versa. Climate humidity also plays a huge role.
Nature of the relief
Rivers flowing for the most part on flat terrain, other things being equal, less water-abundant than predominantly mountain rivers. The latter can be several times higher in annual flow than the plain ones.
There are many reasons for this:
- mountain rivers, which have a much greater slope, flow faster, which means that river water has less time to evaporate;
- in the mountains the temperature is always much lower, and therefore evaporation is weaker;
- V mountainous area more precipitation and more river filling, which means a higher annual river flow.
This, looking ahead a little, is enhanced by the fact that the nature of the soil in mountainous areas has less absorption, and accordingly, a larger volume of water comes to the mouth.
Nature of soils, soil cover, vegetation
River flow in to a large extent determined by the nature of the surface along which the river carries its waters. The annual river flow is an indicator that is primarily influenced by the nature of the soil.
Rocks, clay, stony soil, and sand differ greatly in their carrying capacity in relation to water. Highly absorbent surfaces (e.g. sand, dry soil) will radically reduce the annual flow of the river flowing through them, while almost impermeable surface types (protruding rocks, dense clay) will have virtually no effect on river flow parameters , skipping river waters through its territory without any losses.
Extremely important factor Soil water saturation is also a factor. Thus, abundantly moistened soils will not only not “take up” melt water during spring snowmelt, but are also able to “share” excess water.
Character is important vegetation cover banks of the river under study. For example, those that flow through wooded areas are more water-rich, all other things being equal, compared to rivers in steppe or forest-steppe zone. In particular, this is due to the ability of vegetation to reduce the overall evaporation of moisture from the earth's surface.
Largest rivers in the world
Let's consider the rivers with the most abundant flow. To do this, we present to your attention a table.
Hemisphere | River name | Annual river flow, thousand cubic meters km |
||
South America | R. Amazon | |||
Northern | ||||
South America | R. Rio Negro | |||
Northern | South America | R. Orinoco | ||
Northern | R. Yenisei | |||
Northern | North America | R. Mississippi | ||
South America | R. Parana | |||
Northern | ||||
South America | R. Tocantins | |||
R. Zambezi | ||||
Northern | ||||
Northern |
Having analyzed this data, one can understand that the annual flow of Russian rivers, such as the Lena or Yenisei, is quite large, but it still cannot be compared with annual flow so powerful deep rivers like the Amazon or Congo, located in the southern hemisphere.
River- natural water flow(watercourse), flowing in the depression it has developed - a permanent natural channel and fed by surface and underground runoff from its basin. Rivers are the subject of study of one of the branches of land hydrology - river hydrology (potamology).
River mode- regular (daily, annual) changes in the state of the river, due to the physical and geographical properties of its drainage basin, primarily climate. The river regime is manifested in fluctuations in water levels and flows, the time of establishment and disappearance of ice cover, water temperature, the amount of sediment carried by the river, etc.
River feeding- the flow (inflow) of water into the river from the power source. Nutrition can be rain, snow, glacial, underground (soil), most often mixed, with the predominance of one or another source of nutrition in certain sections of the river and at different times of the year.
Water flow is the volume of water flowing through a cross-section of a stream per unit time. Based on regular measurements of water flow, the flow over a long period is calculated.
Solid runoff is solid particles of mineral or organic material carried by flowing waters.
58. Lakes: classification, water balance, ecology and development.
A lake is a closed depression of land into which surface and underground waters flow and accumulate. Lakes are not part of the World Ocean. Lakes regulate the flow of rivers, retaining hollow water in their basins and releasing them at other times. Chemical and biological reactions occur in lake waters. Some elements move from water to bottom sediments, others - vice versa. In a number of lakes, mostly without drainage, the concentration of salts increases due to water evaporation. The result is significant changes in the mineralization and salt composition of lakes. Due to significant thermal inertia water mass large lakes soften the climate of the surrounding areas, reducing annual and seasonal fluctuations in meteorological elements.
1 Lake basins 1.1 tectonic 1.2 glacial 1.3 river (oxbow lakes) 1.4 coastal (lagoons and estuaries) 1.5 sinkholes (karst, thermokarst) 1.6 volcanic (in the craters of extinct volcanoes) 1.7 dammed 1.8 artificial (reservoirs, ponds)
Water balance- the ratio of water inflow and outflow, taking into account changes in its reserves over a selected time interval for the object in question. The water balance can be calculated for a watershed or area of territory, for water body, country, continent, etc.
The shape, size and topography of the bottom of lake basins change significantly with the accumulation of bottom sediments. The overgrowing of lakes creates new forms of relief, flat or even convex. Lakes and, especially, reservoirs often create a backwater of groundwater, causing swamping of nearby land areas. As a result of the continuous accumulation of organic and mineral particles in lakes, thick layers of bottom sediments are formed. These deposits are modified by further development bodies of water and turning them into swamps or dry land. Under certain conditions they are converted into rocks organic origin.