After completing the table, be sure to indicate how you assess the general condition of the river and the quality of the water in it.
Please note that for convenience, the table can be turned over and the names of the graphs can be written not in rows, but in columns. Then the descriptions of the samples will be arranged line by line. Draw and fill in the tables in the way that suits you, just remember that they should be understandable not only to you, but also to other researchers.
Hydrological regime
The type of river, the amount of water in it, the speed of its flow varies significantly throughout the year. These changes are connected, first of all, with the change of the seasons, with the melting of snow, droughts, rains, i.e. those natural factors that determine the flow of waters feeding it into the river. Characteristics changes in the state of the river over time are called its hydrological regime. The height of the water surface in centimeters, which is measured from some accepted constant mark, is called water level. In the annual cycle of the life of a river, such main periods are usually distinguished (they are called phases of the hydrological regime):
1. high water;
2. flood;
3. low water.
High water is the time of the highest water content of the river. In the European part of our country, floods usually occur at the time of spring snowmelt, when meltwater flows from the entire catchment rush to the channel of the main river and its tributaries. The amount of water in the river increases very quickly, the river literally “swells”, it can overflow its banks and flood floodplain areas. The high water is regularly repeated every year, but can be of varying intensity.
Floods are rapid and relatively short-term rises in the water level in the river. They occur, as a rule, as a result of rainfall, downpours in summer and autumn, or during thaws in winter. Floods usually occur every year, but unlike floods, they are irregular.
Low water is the least water phase of the water regime. On our rivers, two periods of low water are distinguished - summer and winter. At that time precipitation cannot provide sufficient nutrition to the river, the amount of water in it is significantly reduced, big river can turn into a small stream and life in it is supported mainly by underground power sources - springs and springs.
Human economic activity in the catchment area of the river and its banks also affects the hydrological regime. Drainage of swamps, withdrawal of water for domestic and industrial needs, discharges Wastewater etc. lead to a change in the flow of the river. Particular attention should be paid to cases when water is withdrawn for household needs from the catchment area of one river, and the water is used or returned to nature in the catchment area of another. This greatly affects the natural distribution of water and can lead to the drying of some areas and waterlogging of others.
Ill-considered human actions can disrupt the natural course of the change in the phases of the water regime. There are cases when small rivers flowing within settlements suddenly experience floods caused by large discharges of wastewater from industrial enterprises. Such changes affect the ability of the river to
self-purification and affect the quality of the water in it. Therefore, the study of water level fluctuations in rivers and lakes is of great scientific and practical importance.
Water level monitoring
To organize the monitoring of the level is quite simple and quite within the power of schoolchildren and students. Data on regular measurements of the level with an accurate indication of the location of the target, the time of the observation and the characteristics of the weather are valuable information, and the larger the number of these observations, the great value they acquire.
State level observation posts consist of special devices for measuring levels, such as rods or piles. These battens and piles are securely fastened to withstand heavy seas and ice drift. Each post has its own exact topographic mark (height above sea level), which makes it possible to compare the readings of different posts with each other and assess the general situation in the catchment area, basin, etc. If there is no such state water measuring station in your area, on your river or lake, you can organize your own temporary water measuring station. Of course, its data cannot be compared with the observational data of the state hydrometeorological service, since this would require complex geodetic measurements. However, you will be able to trace the change in the water level in the river from season to season and from year to year. The post can also be used as a sampling site for hydrochemical observations.
The most convenient way to equip a water metering post is to use a permanent rail fixed on a bridge support across the river (Fig. 6b). Markings are applied to the rail, preferably with bright oil paint, so that it does not wash off with water and is clearly visible from afar. The rake is installed on the downstream side of the bridge so that it is not broken or torn off by passing ice floes during ice drift.
Rice. 6. Arrangement of water measuring posts (a - pile, b - rack)
Level measurements should be carried out with an accuracy of one centimeter. The mark below the lowest level is taken as the initial measurement mark. It is best noted at the end of summer, during the period of deep low water. This initial height is called the zero of the graph and all other levels are measured in excess above it.
The pile water measuring post looks different (Fig. 6a). First, one pile is installed at the zero level of the graph (5th in Figure 6a). Then, above it, through a certain height (0.5 m, 1 m), other piles are installed using a level. So that the piles do not rot longer, they can be burned at the stake or smeared several times vegetable oil and let the oil soak in. It is even better to hammer scraps of metal pipes into the ground, and in
them to strengthen the wooden piles. On the upper end of the pile, you can put on a nozzle cut out of used plastic dishes. It turns out beautifully and firmly, and most importantly - such piles are clearly visible. Then the piles are numbered in order from top to bottom, and for each pile its height relative to the zero of the graph is noted. To determine the level, a water gauge (a simple ruler can be used) is placed on the pile immersed in water closest to the shore, and the water level mark is noted. The measured water height above the pile is added to the relative height of the pile to obtain a water level mark. For example, pile No. 4 is located at a height of 100 cm above the zero of the graph and is hidden under water by 12 cm. Therefore, the water level is at H = 100+12=112 cm.
Observations of the water level at hydrological posts are usually carried out twice a day - at 8 and 20 o'clock, but you can limit yourself to a single morning observation. If you can't measure the water level exactly at that time, don't worry, measure when you can, just don't forget to indicate the time and date of observation. In cases where you can take readings over several days, try to do it at the same time.
The received data are recorded in the journal in the form of a table 5 . During the flood period, when the water in the river rises especially quickly, observations are carried out more often - after 3-6 hours. The same applies to periods of heavy rains and floods on the river.
Table 5. Results of observations of the water level in the river
Name of the river ........................................
Location of the post...................................
Time (h, min)
Water level above zero graph H, cm
Level change ± h, cm*
FULL NAME. observer
* level change compared to the previous observation.
Based on the data obtained, it is possible to construct a graph of water level fluctuations over the observation period. Then it will be easier for an interested person to navigate your results, moreover, the graphs are clearer than numbers.
Measuring the depth and width of a river
To determine the depths of the river and the features of the topography of its bottom, measurements of the riverbed are carried out. Based on the results of measurement work, it is possible to obtain plans for the riverbed in lines of equal depths - isobaths, as well as determine the areas of water sections of rivers.
Necessary equipment:
rope with markings;
rail with markings;
log to write.
The depth of a river can only be determined by direct measurements using gauge rail or lot. On the major rivers with depths up to 25 m, a lot is used - a metal load weighing from 2 to 5 kg, attached to a strong cable with appropriate markings. AT
In the case of studying small rivers, a water gauge is quite sufficient. It is a wooden pole with a diameter of 4-5 cm with centimeter markings applied on it, while the zero division should coincide with one of the ends of the pole. When measuring depth, the rod is lowered with the zero mark down. The length of the rail can be chosen based on the estimated depths of the rivers under study, but usually it is made no longer than 1.5-2 m. If the river is shallow, then you can measure the depth by fording the river. If the river is deep, then measurements have to be taken from a boat. The easiest way to determine the depth is from a bridge hanging over the river, if there is one nearby.
Attention! Let young explorers measure the depth of the river themselves only in those places where the water is no higher than their rubber boots! Reassure them that this can only be done under the supervision of the group leader or adult assistants. The depth of an unfamiliar bottom can be found out by measuring the bottom of the river in front of you with the help of a water gauge and slowly, step by step, moving after it. You should be very careful, as there may be unexpected holes and cliffs in the river bottom.
In addition to the rail, for measuring work you will need marked rope to determine the width of the river and the location of measurement points and a special journal for entries. The rope is usually marked in advance, before work is carried out. The easiest way to do this is with ordinary threads of different colors, for example, red and blue - each ten-centimeter division should be marked with blue threads, and each meter division with red. You can also select every 0.5 m, for example, with red and blue threads at the same time, this will make it possible not to make mistakes when counting the distance between the measurement points. Instead of threads, you can use multi-colored ribbons, cords, an indelible felt-tip marker or oil paint - the main thing is that the marks on the rope are clearly visible, easily seen during measurements and securely fastened.
The points on the alignment at which the depth of the river is measured are called sounding. The number of measurement points for the river under study should be determined as follows: on rivers 10-50 m wide they are assigned every 1 m, on rivers 1-10 m wide - every 0.5 m, for a river or stream up to 1 m wide, 2-3 measurement points are enough points.
How to measure the depth and width of a river:
On the selected site of the river under study, across the current (this is important!) A marked rope is stretched, and the width of the river is determined from it.
In accordance with the measured width, the number of measurement points and their position on the alignment are determined. It must be remembered that the first and last points should be located directly on the water's edge.
Moving along the rope at the designated points, they lower the measuring rod to the bottom (try to keep the rod vertical!) And fix the division at which the water is located - this is the depth of the river in this place.
Measurement data are logged in the form tables 6 . At the same time, data on the date and time of the measurements and indicate the location of the alignment must be entered in the log. It is also necessary to note the nature of the soil (silty, sandy, rocky), as well as the presence and nature of vegetation in the riverbed (“vegetation absent”, “vegetation in the coastal zone”, Vegetation along the entire riverbed”, dense or sparse vegetation).
Distance from the beginning of the alignment,
Distance between points, m
Depth, m
Soil nature
Vegetation
Who did the work..............
Based on the measurement data, it is possible to build a transverse profile of the riverbed and calculate the area of the water section, i.e. section of the river flow by an imaginary plane in the place of the measurement site (Fig. 7). The area of this section can be found as the sum of the areas of simple geometric figures formed by measuring verticals. These figures can be rectangular trapezoids rotated by 90o (S2, S3 and S5), rectangles (S4) or right-angled triangles (S1), the area of \u200b\u200bwhich is determined according to known rules - the area of \u200b\u200ba rectangular trapezoid is equal to the product of half the sum of the bases (in the example - h1 and h2) height, the area of a right triangle is half the product of the legs, and the area of the rectangle is the product of its two sides. In our case, the bases, legs and sides of the figures will be the measured depths and distances between the measurement points. The resulting cross-sectional area must be recorded in the log in table 7.
Rice. 7. Determination of the cross-sectional area of the riverbed w (m2)
S1 = h1 * b1 / 2 w = S1 + S2 + S3 + S4 + S5
S2 = (h1 + h2 ) / 2 * b2
S3 = (h2 + h3 ) / 2 * b3
S4 = h3 * b4 = h4 * b4
S5 = (h4 + h5 ) / 2 * b5
Dividing the resulting cross-sectional area (w, m2) by the measured width of the river (B, m), we obtain the value of the average depth of the river at the site: hav = w/B.
The water level in a reservoir is the height of the water surface relative to the conditional horizontal plane (that is, the height above sea level).
The following levels of water in the river are distinguished:
- High water is the highest of them. It is formed after the melting of snow, glaciers.
- A flood is a high water level formed after heavy continuous heavy rains. A peak stands out at the flood - a wave that moves along the river at the speed of the river. Before the flood peak, the water in the river rises, and after the peak it decreases.
- Low water is the lowest level, natural and established for a given reservoir.
The Altai rivers mainly belong to the Ob river system. This river crosses the Altai Territory in its upper course. The Ob and its tributaries - Alei, Barnaulka, Chumysh, Bolshaya Rechka and others - have wide, well-developed valleys and a calm current. The water level in the rivers of the region is defined as winter low water and summer flood. They mainly have a mixed diet: glacial, snow, rain and soil.
Water level in the Altai rivers
The river network of the Altai Mountains is well developed (with the exception of the southeastern part). Rivers originate from glaciers, swamps and lakes. For example, on flat mountain ranges from the swamp, the tributary of the Chulyshman River - Bashkaus originates, the Biya River flows out of the Teletskoye Lake, the source of the Katun River is located at the Belukha Glacier.
The rivers of the Kulunda lowland are fed mainly by rain and snow with a pronounced spring flood. In summer, very little precipitation falls on the territory of the region, and the water level in the rivers drops sharply, many of them become shallow, and in some areas they even dry up. In winter, they freeze, and from November to April, freeze-up lasts.
Mountain rivers belong to the mixed Altai type of food. They are rich in water, they are fed by thawing glaciers, atmospheric precipitation and groundwater.
Snowmelt in the mountains lasts from April to June. Snow melts gradually, starting from the north of the Altai Mountains, then in the low mountains, after which it begins to melt in the middle mountains and in the southern highlands. Glaciers begin to melt in July. In summer, rainy days alternate with clear and sunny ones. But prolonged downpours here are a fairly frequent phenomenon, which is why the water level in the rivers rises sharply and quite strongly.
The rivers of high mountains are characterized by glacial and snow type of nutrition. The summer flood is pronounced, although it also occurs in autumn.
For the rivers of the middle mountains and low mountains, two high levels are characteristic in the regime:
- In spring and summer - high water (from May to June).
- In summer and autumn - floods due to autumn rains and melting glaciers.
In autumn and winter, rivers are characterized by low water - the lowest water level in the rivers.
In the mountains, they are covered with ice much later than in the plains, but they usually freeze to the bottom. In some mountain rivers, ice formation occurs on the surface and along the bottom at the same time. Freezing, as a rule, lasts about 6 months.
Mount Belukha is the most important source of food for the rivers of the Altai Territory. The Belukha glaciers are very active, they go down very low, they melt a lot and receive a lot of precipitation.
Rivers receive approximately 400 million cubic meters from this melting process. m. of water per year.
Water levels in the Ob River
Ob — a typical lowland river, but its sources and large tributaries are in the mountains. The Ob is characterized by two floods - in spring and summer. Spring occurs due to water from melting snow, summer - due to water from melting glaciers. Low water is observed in winter.
The river freezes for a long time. Freezing on the Ob lasts from November, and only in April does the ice drift begin, when the river is freed from the ice mass.
Katun River
The Katun is a typical mountain river, its source is in the glaciers of the Belukha mountain. The supply of this waterway is mixed: from the melting of glaciers and due to precipitation. Water levels in the Katun River look like a flood in summer and low water in winter. The flood period starts from May and lasts until September. In winter, the river freezes to the bottom.
Biya river
The Biya flows out of Lake Teletskoye. It is full of water throughout its length. Biya is a river both mountainous and flat.
The water levels in the Biya River look like high water in spring, and in autumn and winter - low water. High water sets in in the spring (starting from April), but in the summer its water level is also quite high, although a gradual decline in water already begins at this time. In November, low water is established on the river and freeze-up begins, which continues until April. Ice starts in April.
Hydrological surveys include a wide range of field work such as monitoring water levels in rivers, lakes and artificial reservoirs, determining river slopes, living areas, flow rates, water discharges, studying river load and much more.
Observations of these elements of the water regime are carried out on specially arranged permanent or temporary water measuring posts and hydrological stations. Depending on the tasks set, the timing of observations and the amount of information, stations and posts (in the GUGMS system) are divided into several categories. Hydrological stations are divided into two categories, river water-measuring posts - into three categories. At posts of category III, observations are made of level fluctuations, water and air temperatures, and ice phenomena. At posts II and I of the category, the volume of observations is additionally increased by determining the flow of water, the flow of suspended and bottom sediments.
When surveying for the construction of engineering structures, departmental organizations arrange posts with a limited period of their work, although this period can range from several months to several years. The composition and timing of observations at such posts are determined by the range of tasks solved in the course of designing an engineering structure. Therefore, in addition to their direct functions - to provide information about the water regime of the watercourse, water measuring posts play an important role in channel surveys, in the work on compiling a longitudinal profile of the river, etc.
water level called the height of the position of the free surface of the water relative to the constant horizontal reference plane. Graphs of level fluctuations make it possible to judge the dynamics of hydrological phenomena and, accordingly, the long-term and intra-annual distribution of runoff, including during floods and floods. To monitor the water levels in the river, water-measuring posts of various design are used: rack, pile, mixed, self-registering.
Rack posts, as the name implies, is a rail fixed on a pile securely driven into the ground, on the bridge abutment, embankment lining or natural vertical coastal rock. The length of the rail attached to the pile is 1¸2 m. The size of the divisions on the rail is 1¸2 cm. Readings of the water level along the rail are taken by eye with rounding up to 1 cm (Fig. 1). It is difficult to fix the level of the current, and often undulating water surface with a higher accuracy, however, for most engineering problems, such accuracy is quite sufficient. If higher accuracy is required, then the rail is placed in a small backwater (bucket), arranged on the shore at the water's edge and connected by a ditch to the river.
Rice. 1. Rack water measuring post
Rack gauge posts are mainly used to observe levels when their fluctuations are relatively small. On rivers with a large amplitude of level fluctuations or during periods of floods and floods, pile posts are used.
Pile water gauge(Fig. 2) consists of a row of piles located along the alignment perpendicular to the river flow. Piles made of pine, oak or reinforced concrete with a diameter of 15¸20 cm are driven into the soil of the bank and the bottom of the river to a depth of about 1.5 m; the excess between the heads of adjacent piles should be about 0.5¸0.7 m, and if the coast is very gentle, then 0.2¸0.5 m. On the ends of the piles, their numbers are signed with paint; the topmost pile is assigned the first number, subsequent numbers are given to the piles located below.
To fix the level on pile posts, a small portable rail is used with divisions every 1¸2 cm; transverse section slats - rhombic, while the slat is better flowed around with water; on the lower part of the rail there is a metal fitting, which allows you to confidently fix the installation of the rail on the head of a forged nail hammered into the end of the pile.
When reading the level, the observer places a portable rail on the pile closest to the shore, covered with water, and writes down the reading on the rail and the number of the pile in the journal.
Of the special tools for measuring levels, one can name the maximum and minimum rails, i.e. the simplest devices that allow you to record the highest or lowest levels for a certain period of time.
Rice. 2. Scheme of the device of the observation tower and the pile water measuring post: 1 - tower; 2 - theodolite; 3 - benchmark; 4 - pile; 5 – water gauge ( h- reading on the rail); 6 - float
Mixed water meters are a combination of a rack post with a pile post. At such posts, fixing a high level is done on piles, and low levels - on a rail.
For continuous recording of level fluctuations, special devices- limnigraphs, which record all level changes on a tape driven by a clockwork. Water metering stations with water level recorders have a great advantage over simple water metering stations. They make it possible to record levels continuously, but the installation of a recorder requires the construction of special structures, which greatly increases the cost of their use.
For constant control over the stability of the rails or piles near the water gauge, a benchmark is installed (Fig. 1), usually along the alignment of the piles of the water gauge, then it is also a constant start (PN) for counting distances, a kind of picketing start.
The mark of the benchmark of the water measuring post is set in the course of leveling work from the benchmarks of the state leveling network. The benchmark of the water measuring station is laid in the ground in compliance with the general rules for installing benchmarks, i.e. its monolith must be below the depth of maximum soil freezing, in a place convenient for leveling, and always outside the zone of flood waters, i.e. above the high water horizon (HWA).
As indicated above, at most water measuring posts, the height system is conditional. The beginning of the height count is null post graph- the height mark, which remains constant for the entire period of the existence of the post. This conditional horizontal plane is located at least 0.5 m below the lowest water level that can be expected in the alignment of the post. At rack water gauge posts, the zero of the graph is often combined with the zero of the gauge rail.
Measurements are started at the post after the zero mark of the post schedule is assigned and the leveling determines the zero mark of the pile head areas, and the difference between the zero marks of the post schedule and the marks of the pile heads is determined. This difference in marks is called registration.
A private system of heights at a water-measuring station makes it possible to solve the overwhelming number of problems in studying the water regime of a river. However, for a number of problems in the design of structures, it is required to know not only conditional, but also absolute (Baltic) level heights. For this purpose, water metering posts, or rather the benchmarks of water metering posts, are tied to the nearest benchmarks of the state leveling network.
The composition of observations at the water gauge, in addition to observations of the level, includes visual observations of the state of the river (freeze, ice drift, clear), weather conditions, water temperature, air, precipitation, ice thickness.
The thickness of the ice is measured with a special rail; air temperature - with a sling thermometer, and water temperature - with a water thermometer.
At permanent water-measuring posts, observations are carried out daily at 8 a.m. and 8 p.m. Average daily level is defined as the mean of these observations. If the level fluctuations are insignificant, then observations can be made once a day (8 hours). When solving special problems, as well as during periods of high water or high water, fixing the level is done more often, sometimes after 2 hours.
The results of observations at the water-measuring post are recorded in the journal.
Primary processing of water gauge observations consists of bringing readings along the rail to zero of the chart of the water gauge station, compiling a summary showing daily average daily levels, and plotting daily levels, on which conditional icons show freezing, ice drift and other ice phenomena that occurred on the river.
Systematized results of level observations at the entire network of water-gauging stations in a given river basin are periodically published in hydrological yearbooks.
In order to obtain full-fledged observational materials and guarantee the safety of the water-measuring station for the entire planned period of operation, it is recommended to specially select a place for installing the station. At the same time, it is desirable that the section of the river be straight, the channel is resistant to erosion or alluvium, so that the bank has an average flatness and is protected from ice drift; there should not be river moorings nearby; the readings of the post should not be affected by the backwater from the dam or a nearby tributary; the post is more convenient to use if it is near locality. There is no need to strictly combine the water metering station with the axis of the future engineering structure.
At hydrological stations, water measuring posts of I and II categories, as well as during departmental surveys, a hydrometric section is broken, used for regular determinations of current velocities, water discharges and sediments. In this section of the river, the water flow should be parallel to the stream, which is ensured by its straightness and the correct - trough-shaped profile of the bottom. If it is planned to conduct regular and long-term observations on the hydrometric site, then it will be equipped with walkways, suspension cradles, or equipped with swimming facilities (ferry or boats).
The benchmark mark of the water measuring station is set during leveling work from the benchmarks of the state leveling network, for periodic monitoring of the stability of the rail or piles of the water measuring station, during measurement work, as well as when creating a high-altitude survey justification.
The benchmark of the water measuring station is laid in the ground in compliance with the general rules for installing benchmarks, i.e. its monolith must be below the depth of maximum soil freezing, in a place convenient for leveling, and always outside the zone of flood waters, i.e. above the high water horizon.
On permanent watercourses, the most characteristic water levels are:
VIU– high historical level, i.e. the highest water level ever observed on this river and established by surveys of old-timers or by visual traces on capital structures;
USVOS– the level of the highest waters for the entire observation period;
WWW– high water level as the average of all high waters;
RUVV- the design level of high waters, which corresponds to the design water flow and is accepted as the main one in the design of structures;
DCS- the design navigation level, which is the highest water level in the navigation period, is necessary when determining the altitude position of the bridge elements;
UMV– the low water level corresponds to the water level in the period between floods;
USM- the level of the average low water;
UNM– low water level;
UL– freezing level;
UPPL– level of the first ice movement;
UNL- the level of the highest ice drift.
During surveys, fluctuations in water levels throughout the area can reach large values, therefore, to compare the depths across the cross section, we introduce cutoff level– a single instantaneous level for the entire survey area. Usually, the instantaneous minimum level in the studied section of the river for the entire time of measurements is taken as the cutoff level. To do this, it is necessary to determine the top marks of the edge stakes in each hydraulic section by leveling.
All measurement results are reduced to a single position of the free surface of the river, which is further considered zero for various constructions: transverse and longitudinal profiles, the river plan in isobaths. In this case, it should be borne in mind that the accepted reference surface corresponding to the cutoff level, like any free surface of the river, is not horizontal.
