CZ307090B6 - A rain simulator for measuring systems - Google Patents

Description

Technical field

The present invention relates to a rain simulator especially for warning systems allowing to quantify the risk of surface runoff formation in a basin by directly measuring infiltration potential in the field under conditions very close to the current hydrological situation.

BACKGROUND OF THE INVENTION

Infiltration of rainfall into the soil is related to the formation of surface runoff, which is a major factor in the development of negative phenomena in river basins, such as floods and soil erosion. Decreasing the infiltration capacity for water leads to an increase in surface runoff. Direct measurement of infiltration in the field is usually carried out in the framework of experimental work, because of its labor intensity and difficult interpretation of results. The basic infiltration parameters are the current infiltration rate and the cumulative total of infiltrated water. The factors influencing infiltration include the input resistance of the soil surface against water penetration, the actual filling of soil pores with water including their hydraulic parameters, water pressure height depending on the roughness and slope of the surface, eventually the properties of terrain depressions etc.

Controlled parameters for measuring infiltration include the start date of the test, the intensity of the simulated rainfall episode (variable or constant) and the height of the initial surface accumulation of water (the equivalent maximum water column height on the soil surface that represents the conditions of the start of surface runoff). The measured parameters include the critical duration of precipitation of the selected intensity and the precipitation total for determining the start of surface runoff formation. As the test continues, infiltration data such as infiltration intensity and cumulative infiltration are collected.

For complex measurements, a classical rain simulator is used in experimental practice, which generates surface runoff and provides parameters of the infiltration process, but it is an operationally complex device, usually of larger ground plan (with infiltration area from several tens of dm ² to tens to hundreds of m ² ) water-intensive and pump-intensive. This practically does not allow simultaneous automated operation of the system of devices side by side (would lead to an increase in the weather station area) and thus does not allow simultaneous testing of more rain intensities. At the same time the soil surface is damaged by water erosion of running water. Portable rain simulators such as McQueen (283 cm ² ) or Kamphorst (625 cm ² ) are also available. However, their use does not imply continuous reuse, is not designed for automated operation, and therefore cannot be operated within flood warning systems.

Other similar devices include infiltrometers, but the inflow intensity is not regulated, thus providing only information on the limit speed and the amount of infiltrated water. Their design (complete covering of the soil surface) separates the test area from the surrounding environment and the condition of the projection of the influence of current meteorological phenomena into the infiltration process is not fulfilled.

In general, the traditional use of field rain simulators and infiltrometers is fundamentally different from the use in warning systems and their rebuilding or refilling is demanding (notwithstanding the high initial cost).

- 1 GB 307090 B6

SUMMARY OF THE INVENTION

The above mentioned drawbacks are eliminated by a rain simulator for measuring systems according to the invention, which consists of at least one infiltration unit comprising a spacer cylinder driven into the soil surface, a level tip connected by an electric line to a control unit connected to the metering units. unit and water distribution from a water source to infiltrate water into the soil through a sprinkler, while the operation data are stored in a data logger.

The rain simulator for the measuring systems according to the invention is characterized in that it is located in a solid terrain at a representative location of the catchment area during the measurement of the infiltration by a duct. The theoretical basis of the device principle is then the genesis of surface runoff from the elemental runoff surface.

The rain simulator for the measuring systems of the invention is also characterized in that the start date of the test and the inflow rate of infiltration water are controlled by the control unit.

The rain simulator for the measuring systems of the invention is further characterized in that it is suitable for automated field measurement of infiltration potential of the soil surface at actual condition, coverage and humidity and is adapted to measure the time to reach an adjustable highest water level after sprinkling the soil surface with selected water inflow rate. .

The rain simulator for the measuring systems according to the invention combines the advantages of both prior art devices (conventional rain simulator and infiltrometer) while being adapted for continuous automated operation within the meteorological station of the flood warning system.

The rain simulator for the measuring systems according to the invention finds its application as an autonomous sensor of stationary or mobile weather stations with the added function of generating warning messages about local flood risk or as a calibration value of model solutions of precipitation-runoff relations. Thus, the alert generation is based either on direct interpretation of instantaneous measurement results or indirectly using concurrently operated numerical models. The set of controlled and measured parameters of the infiltration integrates the influences that act under real conditions in the basin in the formation of surface runoff, mainly as a result of soil saturation with water.

The rain simulator for the measuring systems according to the invention consists of an optional number of infiltration units 8 located at the infiltration measurement site (eg in the area of a weather station). The infiltration units 8 have a common water source 5 (for example, a canister, a watercourse or a water tank) and a common data logger 7 for recording operational data (operating time, infiltration intensity, cumulative infiltration) of each of the installed infiltration units 8.

The infiltration unit 8 consists of a spacer roller 1 driven into the soil surface 9 so as to limit the infiltration area and to vertically direct the infiltration process. The height-adjustable level tip 2 is installed from above, which allows the maximum flood level of the spacer cylinder 1 to be controlled on an electric principle. from below, respectively. from the sloping shallow subsurface runoff. A sprinkler nozzle 3 is installed in the inner part of the spaceblock 1 in such a way as to prevent water loss outside the defined area of infiltration during artificial sprinkling. Each infiltration unit 8 is further equipped with a water dispensing unit 4 that provides water for infiltration at a desired time and intensity. The operating mode of the water dosing unit 4 is monitored by the datalogger 7 and the operation is controlled by the control unit 6. The infiltration water supply is blocked if the level tip 2 indicates that the set water level 10 has been reached. 4 water and further to the sprinkling nozzle 3 is secured by piping

-2GB 307090 B6 water distribution 11. The control unit 6 is connected by the electric conductor 12 to the level tip 2. The electric conductor 12 transmits signals from the control unit 6 for the operation of the dosing unit 4 and for data archiving in the datalogger 7 (start time, end of artificial sprinkling). level tip 2).

The principle of operation of the rain simulator for the measuring systems according to the invention is based on:

selecting the start time of the site's infiltration potential testing (usually by identifying an increased risk of precipitation or surface runoff);

selecting the i-th infiltration unit 8, or selecting the operation of several infiltration units 8 simultaneously (with the same or different sprinkling parameters);

the choice of sprinkling intensity (given by the site conditions and the periodicity setting of the critical rain): determines the setting of the dosing unit 4;

selection of the height of the initial surface water accumulation, determined by setting the level tip 2 (taking into account the slope conditions, the type of surface including the agrotechnics performed and other influences);

selecting the number and placement of the infiltration units 8 at the infiltration measurement site (given by the anticipated concurrence and periodicity of testing, as well as the hydrophysical properties of the soils so as to ensure sufficient time lag between tests in the same i-th infiltration unit 8);

the operating data are registered in the datalogger 7 and in connection with the operation of the warning systems it is particularly important: the sprinkling intensity and the time required to reach the set highest level of water level 10 above the infiltrated soil surface 9 in the spaceblock

1.

In the period prior to testing the infiltration potential of the i-th infiltration unit 8, the soil surface 9 including vegetation as well as the natural soil profile are exposed to normal meteorological and hydrological conditions of the site of installation. Upon reaching the criterion for initiating artificial infiltration (sprinkling), the water from the water source 5 is fed by water distribution 11 via a dosing unit 4 at a selected flow rate to the sprinkling nozzle 3 and distributed over the soil surface 9 the infiltration should correspond to the probable rainfall intensity of the selected critical duration of rain.

After the start of artificial sprinkling, continuous infiltration with controlled water supply infiltration rate into the soil is carried out in the first phase of the measurement until the highest water level 10 is reached in the limiting cylinder for the first time L Measured duration of sprinkling of given intensity and total units of water column) expresses the parameters of critical rain that would cause surface runoff (the infiltration capacity of the soil profile in specific natural conditions is exceeded). This data is subsequently used by the flood warning system according to various methodologies. If this rainfall is measured in the vicinity of the installed rain gauge, either the risk is reported by an autonomous warning station or the measurement is used as a control value of a parallel running numerical model of a small flood warning system.

The continuous measurement then passes to the second phase of water infiltration into the soil. Upon reaching the level tip 2 with the rising water level 10 above the surface of the soil 9, the water supply is stopped until the level 10 drops below the level of the tip 2 (the imaginary contact of the tip 2 and the level 10 does not open). Thereafter, the water supply process is resumed by the dosing unit 4 and the intermittent sprinkling continues as long as set by the control unit 6. Measured data of the i-th infiltration

They are registered by the datalogger 7 and are further used in the evaluation of the course of infiltration.

The advantages of the rain simulator for the measuring systems according to the invention can be summarized as follows:

versatility of the device for the determination of critical parameters of rain (phase 1 of measurement), causing surface runoff at the measured site, and providing information on current conditions of water infiltration into soil (phase 2);

possible concurrence of measurements with different parameters of sprinkling, soil surfaces, etc .;

compactness of the constructional solution and structure of the system including simplicity of connection to existing or newly built flood warning systems (solution as an autonomous sensor of an automatic monitoring station);

simplicity of construction, measurement automation and the possibility of adaptation to local conditions (selection of the space of the spacer cylinder, number of infiltration units), saving of financial resources;

respect of current meteorological and hydrological conditions at the time of measurement (surface properties, soil moisture, etc.).

Clarification of drawings

In the accompanying drawings, FIG. 1 shows the basic functional connection of one infiltration unit 8 with links to other components of the rain simulator for the measuring systems according to the invention. In FIG. 2 is a multiple circuit diagram of infiltration units 8 for sequential or concurrent measurement of infiltration with an arrangement allowing data transmissions to a common central data logger 7 for several infiltration units 8 (i = a to z). An exemplary embodiment of the spacer roller (left) with the means for driving it into the soil (right) is shown in FIG. 3. The spacer roller 6 is driven into the soil up to the level of the upper annular surface of the level tip 2, and another design can be chosen.

DETAILED DESCRIPTION OF THE INVENTION

The following examples of embodiments of the rain simulator for the measuring systems according to the invention merely illustrate without limiting it.

Example 1

The rain simulator for the measuring systems according to the invention was manufactured in 2010 at the Research Institute of Soil Rehabilitation and Soil Protection, Prague, CZ, and was connected to the Fiedler-Mágr weather station České Budějovice, CZ.

The spacer roller is formed by a stainless steel ring of internal diameter 100 mm, height 50 mm (F = 78.5 cm ² ) and is driven into the soil by a turning adapter and a hammer - see Fig. 3. An adjustable level tip 2, made of stainless steel screw M4, is attached to the cylinder 6 by a ring.

The IWAKI model HRP-54H-1P2 (built-in horizontal with pulse control, 12 V supply voltage, digitally controlled stroke range up to 720 strokes / min ⁾ , representing a maximum flow rate of 38 ml.min ' , which in relation to the infiltration area of 78.5 cm ² corresponds to the minute total

-4GB 307090 B6

4.8 mm). The water distribution 11 is solved by a transparent PE hose of 6 mm diameter, any mechanical impurities from the water source 5 are captured by the Pe filter of the suction basket. The electronic part of the control unit 6 is based on a voltage-controlled frequency generator up to 12 Hz and a level 10 detector (both according to the NE555 circuit) and a logic electronic circuit - gate. The measurement start command is generated by the M4016-G Universal Recording and Controller Relay 6 of the telemetry station. Fiedler-Mágr after evaluation of incoming SMS message or based on evaluated information about the beginning of rain. The same unit 6 performs the role of a data logger 7 in addition to the remote data transmission function to the Internet server. The whole measuring set is powered by a common maintenance-free gel accumulator 12 V / 9 Ah.

If the general empirical equation Duba and Němec (Dub O., Němec J. et al. 1969: Hydrology, SNTL Prague) is used for the relationship between the duration, intensity and periodicity of rain

H _s = [a. log (t) + b]. N ⁿ and the parameters are set eg for the Hamry station (Chrudim district):

a = 8.86; b = 1.8; n = 0.22; and successively times t [min] = 2, 5, 10, 15, 30, then the described rain simulator design solution for measuring systems is able to simulate the following critical rains according to the given relation:

H _s = 9 mm for t = 2 min and the corresponding repetition time N = 20 years

H _s = 22 mm for t = 5 min and repeat N = 100 years

H _s = 42 mm for t = 10 min and repetition N = 500 years

H _s = 65 mm for t = 15 min and repetition N = 2000 years

H _s = 113 mm for t = 30 min and repetition N = 10 000 years.

Thus, the implemented rain simulator variant for the measuring systems according to the invention makes it possible to simulate virtually any critical totals for a given rainfall station with any real comparable repetition rate (see maximum sprinkling intensity 4.8 mm.mm -1).

Industrial applicability

The solution concerns a rain simulator for measuring systems for measuring the infiltration potential of soil in the field, under the conditions of the current meteorological and hydropedological situation. From the results of measurements it is possible to deduce the critical parameters of rain, which with a given probability will cause a surface runoff at a particular habitat, which is risky both in terms of the development of erosion processes and in terms of flood formation in small catchment areas. The equipment can be manufactured either as an autonomous sensor of automatic monitoring stations or as a stand-alone device. The rain simulator for measuring systems consists of one or more infiltration heating units depending on the application.

Claims (4)

PATENT CLAIMS Rain simulator for measuring systems, characterized in that it comprises at least one infiltration unit (8) comprising a spacer roller (1) driven into the soil surface (9), further a level tip (2) interconnected by an electric line (12) ) with a control unit (6) which is connected to a dosing unit (4) and a water distribution (11) from a water source (5) to infiltrate water into the soil (9) through a sprinkler (3), and the control unit (6) is connected to a data logger (7) for archiving the measured data. Rain simulator for measuring systems according to claim 1, characterized in that the metering unit (4) allows operation for various preset sprinkling intensities. Rain simulator for measuring systems according to claims 1 and 2, characterized in that, during the measurement of the infiltration by means of a duct, it is placed in a solid terrain at a representative basin location. Rain simulator for measuring systems according to claims 1-3, characterized in that the control unit (6) is adapted to set the start of the test and the inflow rate of infiltration water.