Where in the irrigation system of the tree nursery water drops away?
Irrigation optimisation: where irrigation water could be economised?
Required data:
·
Irrigation
amount according to areas
·
Precipitation
·
Terrain division with slopes and sewers
·
Flow in field-sewers in inflow- and outlet areas
·
Plant type, pot size, pot arrangement
·
Evapotranspiration of the different pot- and
planttypes
·
Wind, temperature, solar radiation
·
Evapotranspiration subsoil
Water loss evaluation
Seepage though/ besides plastic foil
Irrigation
water + precipitation water– transpiration – flow sewer inflow-area
leakage pipe system
flow sewer inflow-area – flow sewer outlet-area
Irrigation optimisation
Soil
humidity in pots in the course of a day
Irrigation
and precipitation in the course of a day
Flow rate
Optimal
irrigation water amount: sufficient humidity in pots with minimal outflow
Needed data set
·
Intra-day temperature
·
Intra-day wind velocity
·
Intra-day weight loss div. Pots
·
Intra-day
soil humidity in pots
·
Daily
precipitation
·
Daily
irrigation water amount
·
Intra-day
flow sewers inflow and outlet areas
Data Collection
Irrigation amount
Data nursery. Nozzle type and amount, water bills, pump activity. Frequency and time
of irrigation.
Calculation
irrigation per square meter depeding different areas, plants and pot sizes.
Terrain classification
with slopes and sewers
Data nursery, maps
Precipitation measurement
Precipitation gauges (or raingauges if only liquid precipitation can be
measured) are the most common instruments used to measure precipitation.
Generally, an open receptacle with vertical sides is used, usually in the form
of a right cylinder, with a funnel if its main purpose is to measure rain.
Since various sizes and shapes of orifice and gauge heights are used in different
countries, the measurements are not strictly comparable (WMO, 1989a). The
volume or weight of the catch is measured, the latter in particular for solid
precipitation. The gauge orifice may be at one of many specified heights above
the ground or at the same level as the surrounding ground. The orifice must be
placed above the maximum expected depth of snow cover, and above the height of
significant potential insplashing from the ground. For solid precipitation
measurement, the orifice is above the ground and an artificial shield should be placed around it. The most commonly
used elevation height in more than 100 countries varies between 0.5 and 1.5 m
(WMO, 1989a).
The
measurement of precipitation is very sensitive to exposure, and in particular
to wind.
(World
Meteorological Organization, (1989))
Flow rate pipes
To measure
the flow rate there are a couple of options. The first would be optical
detection. If we can add view ports to your piping and the liquid is not clear
it should work. We could use aligned LEDs and photocells for a rough level
measurement. Or, even simpler, if there is an access to the pipes, we could
measure the water height in the pipe every hour. The next option would be
ultrasonic level sensors. I don't know how having multiple on the same line
would effect them. If you are just looking for an emergency shut off in case
the level drops a single sensor would do.
ExactSonic II - portable ultrasonic flow meter for liquids
This
principle of measurement is also referred to as the transit time difference
method. For measuring the flow rate of liquids using this technique, ultrasonic
pulses are sent and received simultaneously through the medium in the direction
of flow and against it. The sensors work alternately as transmitter and
receiver. The transit time of the acoustic signals filtered through the medium
in the direction of flow is shorter than that against it. The difference in
transit time Δt is
measured and can be used to calculate the average flow velocity of liquids
filtering through the acoustic path. After measuring the flow velocity and with
the pipe cross-sectional area, volumetric flow can be calculated.
These
ultrasonic flowmeters have many benefits, for example, the measuring
instruments produce accurate results in just a matter of minutes, they are easy
to install and operate, there is no process interruption and there are no pipe
restrictions. As a result, there is no pressure loss and therefore, time and
cost savings as the ultrasonic flow meter is easy to install on the pipe.
Advantages
of non-invasive measuring with the ultrasonic flowmeters:
- installation without process
interruption or shut-down
- easy and
cost-effective assembly
- light-weight
ergonomic design
- ideal for use in maintenance
areas and commissioning
- testing
fixed measuring equipment
Device-related
advantages of the ultrasonic flow measurement equipment compared to other
products:
- no zero point alignment of
the flow meter necessary
- coverage of the most frequent
industrial applications for flow measurement of liquids with just two
transducer sets
- high-capacity data logger with
numerous parameters for pipe materials and mediums
- stable and reliable results
even under difficult conditions
- excellent
reproducibility of results
Measurement-related
advantages of the ultrasonic flow meter:
- non-contact
measurement
- independent of pressure,
temperature, conductivity and viscosity
- unlimited plant availability,
as no process interruption
- no pressure losses when
measuring flow rate, no risk of leakage, no cleaning necessary
- no mismeasurements as a result
of blocked impulse pipes
- logging of lowest flow
velocities (min. 0.2 m/s) resulting in high measuring dynamics
(Hönzsch GMBH (2014))
Weight measurement plants
Continous
weighing of pots.
Maybe
possible to film analogue scale next to watch during day to have continuous
data.
Evapotranspiration subsoil
Weight measurement soil
Continous
weighing of a part of soil, packed in tissue and stored in the soil when not
weighed in order to be able to calculate a realistic transpiration rate.
Tensiometer (Soil humidity)
A
tensiometer is a device for monitoring soil water. It consists of a porous cap
(usually made of ceramic with very fine pores) connected to a vacuum gauge.The soil humidity must me measured to be able to calculate the water circles of this area.
Best would be to install several devices on strategic points of the area and to make continuous measures, which can be compared with the irrigation, flowrate and temperature data.
Temperature, Air humidity
Continuous
measuring necessary for comparability of data
Analogue measuring
Stationary measuring
on fields with thermometer. Continuous notation by hand.
Data logger for humidity,
temperature, air pressure and CO2
·
Continuous data recording
over long periods owing to the long battery life and the large data
memory.
·
The data loggers can
operate in an Ethernet network. The measured data is available in real time
and it can be displayed and saved simultaneously on a computer.
·
Maximum reliability of
measurement data transmission is guaranteed by the integrated Ethernet
interface.
·
Easy evaluation and
visualisation of measurement data. The powerful SmartGraph3 software is
included in the scope of supply.
·
Local visual and acoustic
alarms for fast decisions in the field.
·
Modern enclosure with
large display.
(E + E Elektronik Ges.m.b.H (2016))
Wind
Wind
velocity is less difficult to measure than atmospheric moisture A number of
different whirling cup anemometers are available that either register total
miles of wind passed in a given time interval or give continuous records of
wind velocity These instruments measure only the average values of the
horizontal component of the wind To measure the instantaneous velocities in the
major direction as well as those to the right and left and up and down is much
more difficult and requires specialized equipment Pressure plate anemometers
hot wire anemometers or pressure tube anemographs are generally used for this
purpose and the scale and frequency of the fluctuations measured depends upon
the inertia of the instrument used The wind measurements required in the
evaporation equation can be obtained with standard instruments Wind velocity is
measured at two levels with a pair of contacting cup type anemometers Wind
direction is measured at the upper level only The type of wind record required
depends on the kind of humidity instruments being used If continuous records of
atmospheric moisture are being obtained as from dew point recorders or hygro
thermographs continuous records of wind velocity will be required in order to
determine the rate of evaporation for short tune intervals If however only
integrated values of atmospheric moisture are being obtained as from chemical
absorption hygrometers continuous records of wind velocity are unnecessary but
only an indication of the total miles of wind passed during the time interval
for which the moisture measurements apply The fact that the required wind value
in the evaporation equation is the difference in velocity at the two levels
makes it unnecessary to apply a correction factor to the readings of either
instrument Wind velocity enters the formula also in the determination of z zi
and here actual velocities are required However failure to apply the small
correction factors to get true wind speeds at the two levels will result in
errors so small they can be neglected.(Charles
Warren (1942))
Literature
World
Meteorological Organization, (1989): International Workshop on Precipitation Measurements B. Sevruk, ed.)
Hönzsch GMBH (2014). Retrieved
from http://www.hoentzsch.com/en/products/ultrasonic-ua/ on
18.03.2016.
E + E Elektronik Ges.m.b.H (2016). Retrieved
from http://www.epluse.com/en/products/humidity-instruments/humidity-temperature-logging/humlog20/ on
18.03.2016.
Measurement
of Evaporation from Land and Water Surfaces (1942) by Charles Warren
Thornwaite,Benjamin Holzman
