Irrig quiz 2

Irrigation and Drainage Engineering - Lesson 1: Water Resources of the Philippines and its Demand in Various Sectors

• Irrigation is the science of artificially applying water to land based on crop water requirements during the crop period, as defined by Garg (1996).
• Irrigation engineering focuses on the analysis and design of systems that optimally supply water to meet plant needs, for food, landscape, or other purposes.
• Irrigation water supplements rainfall, soil moisture, and capillary rise, addressing situations where full crop water requirements cannot be met due to limited water availability.
• Deficit irrigation involves life saving or supplemental irrigation when water is scarce.
• Beyond crop nourishment, irrigation is used for field preparation, climate control (cooling and frost prevention), and salt leaching.

Advantages of Irrigation

• Irrigation enhances agricultural productivity and enables multiple cropping cycles each year.
• Irrigation creates employment opportunities.
• Irrigation reduces the risk of crop failures.
• Irrigation leads to a stable food supply at reduced prices, following supply and demand economics.
• Irrigation improves the socio-economic circumstances for farmers.

Disadvantages of Irrigation

• Over irrigating can lower crop yields.
• Over irrigation can result in leaching of pesticides, insecticides, nitrogen, and nitrates into groundwater and surface water.
• Inadequately drained soils can experience salinity and waterlogging.
• Faulty canals can lead to waterlogging due to excessive seepage.
• Over pumping groundwater can compromise aquifer structures and lead to land subsidence.

Purpose of Irrigation

• Irrigation provides essential moisture for plant development.
• Irrigation provides a means for fertilizer application, known as fertigation.
• Irrigation leaches or dilutes salts present in soil.
• Irrigation aids in soil preparation and manages airborne dust.
• Irrigation improves the environment for plant development with cooling and frost prevention.

Sources of Water

• Natural resources provides the water for irrigation from rain, snow, hail, and sleet as the original water supply.
• Groundwater and surface water serve as the primary sources for irrigation.
• Three main considerations appraising water resources for use in irrigation: water quantity, water quality, and reliability.
• Natural water sources include springs, rivers, lakes, rainwater, and ponds.
• Man-made water sources include tube wells, wells, hand-pumps, canals, and dams.

Classification of Water Sources

• Surface water sources: Lakes, ponds, tanks, rivers/streams, and storage reservoirs.
• Groundwater sources: Open wells, tube wells, artesian wells, springs, and infiltration.
• Water for irrigation comes from either surface water, groundwater, or both, dependent on rainfall.

Surface Water

• Surface water includes water found in oceans, rivers, lakes, ponds, and streams.
• Surface water collects from direct runoff from snow or rainfall.
• Rainfall greatly affects available surface water.
• Surface water sources include river, lake, and reservoir supplies.
• Dams and reservoirs artificially store water.
• Constructed canals or open channels move reservoir or river water to farm fields, which is then applied to fields, or farm irrigation structures.
• Water is transported by gravity or pumps using pipes.
• Rivers & streams, reservoirs, tanks, ponds, & lakes represent surface water sources.

Components of Surface Water

• Rivers are natural watercourses, usually containing fresh water, that flow toward other bodies of water, or the water may percolate into the ground, or completely dry before reaching another body of water.
• Reservoirs are natural or artificial storage areas for water derived from dam impoundments or artificial excavation.
• Lakes are inland bodies of water that are larger and deeper than ponds, and they are distinct from lagoons as they are not part of the ocean.
• Ponds are small, standing bodies of water, naturally occurring or man-made typically shallower than lakes with aquatic plants.
• Tanks consist of excavations used to store water to be used as an important water source.

Ground Water

• Ground water originates from rainfall, infiltrating the soil, and moving into the groundwater table.
• Ground water frequently exhibits elevated concentrations of dissolved solids, increased hardness relative to surface water, reduced color levels, dissolved gases, and absence of microbial contaminants.
• Wells are typically used to extract ground water.

Methods of Ground Water Extraction

• Extraction methods for groundwater: Dug wells with or without straining walls, Bore wells, Cavity bores, Radial collector wells, Infiltration galleries, Bore & tube wells.
• Springs are locations in which ground water naturally emerges from the ground.

Lesson 2 Irrigation in the Philippines - Historical Periods

Pre-Spanish and Spanish Period (17th-19th century)

• During this time the Banaue rice terraces were built.
• "Zanjeras" emerge (Spanish term for turn out).

American Colonization (20th century)

• In 1908, the government began to engage in irrigation through BPW (Bureau of Public Works).
• Act 2152 (Irrigation Act of 1912) granted authority to the Irrigation Division to utilize public waters, examine, construct, run, and maintain irrigation systems, and collect Irrigation Service Fees (ISF).
• Act 2652 (1916) authorized loans to private irrigation systems managed by landowner associations with service areas of 25 ha or less.
• In 1924 the Irrigation Division became a section in the BPW's Design Division.

Japanese Regime (1937-1945)

• Irrigation development was minimal.
• Most irrigation systems deteriorated.

Philippine Independence

• The Irrigation Division was reactivated in 1945.
• Republic Act 3601, resulting in the National Irrigation Administration (NIA), passed Congress in 1963.
• The NIA is tasked with planning, developing, executing, & maintaining irrigation-centered projects/systems nationwide (Mejia, 1999). NIA also develops water for physical infrastructure, technical maintenance, etc.
• Presidential Decree (PD) 552, implemented during President Marcos' administration in 1974, granted authority to communal irrigation systems to secure NIA assistance, while requiring Irrigation Associations to refund 10% of the direct construction fees to NIA. Implies Communal IAs should be capable of collecting payments from farmers.
• In 1975 NIA partnered with the Farm Systems Development Corporation (FSDC) where NIA constructs communal irrigation systems while FSDC would manage IAs. This was a very short lived partnership due to failures on institutional and technical collaboration.
• Participatory Pilot Projects began in Laur, Nueva Ecija (1976), to gauge the effectiveness of community organizing methodologies in securing IA involvement in rehabilitation of communal systems (Bagting-Siclong and Pinagbaryuhan CIS).
• The participatory program grew to include two additional communal irrigation systems in Camarines Sur (Aslong and Taisan) in 1979.
• In 1980 participatory approach adopted across all communal irrigation system projects.
• The Local Government Code (LGC) was enacted in 1991, instructing national agencies to transfer irrigation functions to local government units (LGUs), authorizing LGUs to utilize funds for CIS and SWIP infrastructure projects.
• Agriculture and Fisheries Modernization Act (AFMA) or RA 8435 was enacted in 1997, instructing the NIA to transfer irrigation systems to LGUs, to strengthen both agriculture and fisheries with modernization and greater participation of farmers and private sector.
• Includes two large reservoir-type projects which enable year-round irrigation: Upper Pampanga River Integrated Irrigation System (UPRIIS) Project in Nueva Ecija, and Magat River Multipurpose Project in Isabela

Comparison Between National and Communal Irrigation Systems

• National Irrigation Systems feature areas larger than 1,000 ha, implemented/constructed solely by the NIA, and they have the NIA in charge of the operational maintenance. Water fees are paid via irrigation service fees and operation uses government funds.
• Communal Irrigation Systems feature areas less than 1,000 ha, have NIA with farmers participation for implementation/construction,, and Irrigator Associations operate and maintain. Water fee amortizations provide income to Irrigator organizations and capital cost recovery.

Small Water Impounding Projects (SWIPs)

• A Small Water Impounding Project (SWIP) is a water storage structure that is used for flood and soil conservation during the rainy season.
• The reservoir serves as a supplemental source of water for irrigation and fisheries.

Small Farm Reservoir (SFR)

• Small water impounding earth dam structure to store rainfall with a typical area of 300-2,000 square meters.
• Embankments measures less than 4 meters above ground level.
• Bulldozers (or manual labor) builds this reservoir and irrigation is typically done with pumps or PVC siphon pipes.
• SFR's provide water for rain-dependent regions of the farm.
• SFR is a useful sources of water for irrigation, aquaculture, livestock and small scale watering.

Types of Irrigation Systems According to Source & Management

• According to source the various water sources for irrigation systems are:
  • Reservoir-type that utilizes a reserve water source for on demand allocation
  • Diversion-type that gets water directly from stream flow and is diverted toward the area of service
  • Pump-type source require a pump to lift the water from underground or surface water to the surface.
• According to management, irrigation systems are national or communal.
  • National systems remain under the management of government agencies that fund construction, and operations.
  • Communal systems are under a farmer's group, constructed from communal system types (indigenous, assisted and turned-over).
    • Indigenous systems are built by farmers with little-to-no government assistance.
    • Assisted systems are constructed with the government's aid in infrastructure (but are later passed down to the farmers to fully manage). -Government build turned-over systems but later shift those same system ownership.

Lesson 3: Methods of Water measurement in Open Channels

• Knowing the quantity of water available is essential for irrigation water management either where channels are open or piped.
• Determining volume of water used may be done by measuring the rate of flow as well as the rate of water.
• Conversion factors are needed to simplify changing units of measurement to another.
• Water is measured as volume of water at rest and as rate of flow while water is moving.
• Units used to measure the volume are litre, cubic metre, hectare-centimetre, hectare-metre etc.
• Units used to measure rate of flow are litres/second, cubic metres/second etc.

Measurement Units

• One litre equals one cubic decimetre (1/1000 cubic metre).
• One cubic metre is a volume equal to a cube that has 1 metre length, width and depth.
• A hectare centimetre is a volume necessary to cover 1 hectare (10,000 sq. m.) up to 1 centimetre(1 ha-cm = 100 cu m= 100,000 litres).
• A hectare metre is a volume necessary to cover ​​1 hectare (10,000 sq. m) up to 1 metre (1 ha-m =10,000 cu m= 10 M litres).
• One litres per second is equal to a continuous flow amounting to 1 litre passing a point each second.
• One cubic metre/second is equivalent to a stream at 1 meter width & depth, and flowing with 1 metre/second velocity.

Methods of Water Measurements

• Volumetric or volume methods
• Area - Velocity Method
• Measuring Structures (Weirs, Orifices and Flumes).
• Tracer methods.

Volume Methods of Water Measurement

• This method is suited for measuring small irrigation streams.
• Water is collected in a container of known volume and the time taken to fill the container is recorded.
• Rate of flow is equal to the volume of the container divided by the time required to fill (in seconds).

Area-velocity Method

• This method utilizes the multiplication the cross area of open channel with the average velocity of water to determine the rate of water flow.
• Measuring the cross sectional area is done by measuring the depths.
• The depth can be measured via soundings rods/weights, or with echo-depth sounders for measurement accuracy.
• The entire cross section is divided into subsections, whose average velocity (through current meter or float) determines total discharge amounts.
• Greater numbers of segments will increase the area of discharge to 10% of segments and segments/ velocities that contrast one another to 20%. Segment width cannot be more than 1/20-1/15th.

Float Method

• Inexpensive and simple way to measure surface velocity.
• Mean velocity is measured by using correction factor and finding the time for an object to travel downstream. Formula: Vsurface= L / t (where L is travel distance and t is travel time). - Vmean = k x Vsurface; where ‘k’ ranges between 0.8 to 0.9 (rough to smooth beds). Steps include: minimal turbulence, mark start/end, time should exceed 20 seconds (if possible), drop object upstream, begin/end watch by tracking objects' course to upstream marker (and to corresponding downstream maker).
• You should repeat the measurement at least 3 times and use the average velocity in further calculations.

Current Meters

• Using current meters can measure area velocity/flow at the location where the measurement is taken.

• Current meter is constructed from a wheel or vane that rotates from water momentum. Depth of the surface, as well as the speed of the propeller, is measured to determine velocity.

• Velocity can be determined via the revolutions/minute (with aid of calibration graphs and tables). Procedure for determining the channel velocity using the meter:

• Secure tape across the entirety cross channel, and span divisions across no less than 25 sites . Use tighter, closer, intervals for channel's deep region(s).

• Begin with at the water's edge, and cite the space firstly.

• Then, depth and velocity. Stand with meter directly down stream such that you can be accurate and least affected by momentum.

• Hold firm (vertically), with velocity meter. - Check to ensure the meter has contact with the water, and that the current and region are free of obstacles and interference . The person taking the notes must ensure that all details from the position, depth at a certain time are recorded.

• Measurements may be done once/twice per subsection. - Velocity should be done for each part at 0.6x total depth as measured at the H2O Surface (where depth (d)< 60 cm ). For 0.2-0.8 subsections (where greater d > 60cm).

• Readings require to be obtained with (minimum) 40 s.

• Calculate discharge in the field. If any section has more than 5% of the total flow, subdivide that section and make more measurements. - Current velocity and speed has to be measured in relation to linearly measuring the stream or the channel, as expressed via the following formulation: v = aNs + b, (a/b are variables, v = stream/measure velocity, and Ns relates towards (number of revolution/second) of the meter.).

Lesson 4 Weirs

• Effective irrigation water utilization must meet flow rates and volumes quantitatively. Open channel flow is hard to measure as a result of velocity variations across the channel.
• The Weir is a calibrated instrument used to measure flow rate & used at canals/outlets or channels.

Weir Terminology

-Weir Pond: Channel segment (just upwards of it) approaching the weir.

• Weir Crest: Edge across from the weir.
• Broad-crested weir: This weir has a horizontal (or approximate) crest at sufficient length according to flow. When the crest runs horizontal, lines are said running parallel, and pressure is exerted.
• Sharp Crested Weir: The edge has a thin crest allowing sheet H2O has contact with the surface. It should allow liquid/H₂O (from the weir) to flow uninhibited).
• Head: The depth of the water above the weir.
• End Contraction: Horizontal space ranging from the crest (of weir), and to where the (weir pond’s) end.
• Weir Scale/Gauge: Graduated scaling installed to measure head & crest
• Nappe: Represents discharge/overflow

Advantages

• Easily built
• Able to handle range/types of measured flows accurately
• Easily adjustable/portable
• More effective than orifices in rating discharge

Disadvantages

• Large head requirements from the free flow
• Maintenance involving removal of outside debris is pertinent.

Classification of Weirs

• These devices are primarily organized/classified by sharp crest or broad-crested notches or openings .

• Generally speaking, sharp measurements are made (especially across the farm).

  -Rectangular, Cipolleti or Trapezoidal, Triangular Weir

Cipoletti Weirs

• The Cipolletti weir is trapezoidal with a 1:4 (horizontal:vertical) sideslope inclination which obtains higher discharge. It is a fully contracting wier. The notch must be measured by least 3H, or no shorter than 4H.

• To analyze Cipolleti weir, there are notch splits amongst triangular & rectangle weirs.

    -The rectangular formulas have been measured to: Q1 = CLH1.5 (discharge in regular notch), Q2 = CH2.5  (discharge in triangular notch, so cumulative discharge is represented as: Q = Q1 + Q2, (or Q=CLH1.5+CH2.5)
    -By virtue of this assumption, formula that governs discarge is expressed via:  Q = CLH1.5 = 0.0184LH1.5 (or)  Q = 0.0186LH1.
  

V-Notch Weir

• A sharp notch in the “V” shape causes small variations with the discharge & more accurate determination (than rectangular Weir). Head must be measured more than 4H from up stream of the weir/channel.

Broad Crested Weir

• Should measure fewer then 2x the weir crest width; else its recognized as a Crested Weir. Flow here is dependent on two ends (labelled A - upstream & B-downstream).

• After equation and applying Bernoulli formulations, discharges are:

  • Maximum at a point from: QMax = Ca Lx √(2gH); where the end result of the weir and H = head. QMax at a greater distance of H: aL √gH (then reduced to) QMax =1.73LxCx L x Hb^2(H = upstream distance of the top and height).

• These can also be suppressed or contracted where the Lateral flow is is suppressed/contracted when ends (of the weir and their notch are side by side with the approach channel).

• Side dimensions in the approach channel must be far removed (otherwise what fully contracts vertically and laterally is the Unsuppressed form of the aforementioned weir.

Rectangular Weir

• As result of the shape, rectangular weirs have water depth affected at the condition from either crest, contraction, or incoming speed/elevation. That affect/increase (the water's suppression and contraction); although they are all connected. Formula as well as considerations factor together regarding calculation. The Weir (Figure 6.5) with H as the overall depth /head can be derived as: Q = Lsd. 2gy, where a = Lxdy, and all discharges are expressed with Ca, in the following progression:

• Q=LCa integration 2gy = CaL√2gy (2/3 y(3/2), with the total amount being Q = 2/3 Ca√(glh^1.5). If Q = L/s, then calculation is simplified to: Q= CLH^(1.5), to 0.0184Lh) For a single sided contraction is represented :Q= 0.0184(L + 0.1H)H(1.5) ,with both sides being (L= 0.2h)H^(1.5)

Lesson 5 Flumes

• Parshall flumes are devices used for flow measurements through channels when depth of flow and head drop remain insignificant and the channel bed shows a subtle (gentle) slope. These tend to consist mostly of a merging portion with its levelled floor (such as the throat section and an upward sloping floor).
• Determine by width: 7.5 cm - metres with structural dimensions

Flow in Parshall Flumes

• Parshall flumes are classified in three clusters from Small, Very Small and Large scale.

• Measurement from water is to done of Ha and Hb • Discharges can occur under either free or underwater capacity and submerged water downstream measures how much ETo the discharge has. In other words under "free" a head is measured at any time frame and has an Ha for the submerged water at downstream (with an Hb).

• Flow in the Submerged water only remains when the ratio between what's under stream to upstream is around a ratio that is as well around : • 0.5, for where range among width: 2.5- 7.5 -Cm •0.6, for where reach: between 1.5- 22.5cm • 0.7 for width ranges ranging from 3.0 to 24 Cm. The measurement of Q: has to be taken with C, Q and H ; all with various ranges regarding size from which all determine width from H that measures head.

Time Domain Reflectometry

• Is an accurate method to define discharge (in fpson as well as the heads).

Advantages

• Relatively effective (drops from total header are minute)
• Work independent from rate of change of the velocity
• Has capability to self-clean in the event of sediment (or deposition through sand).

Cut Throat Flumes.

• Channel geometry has two walls, and measurements calculate how much ETo they let through on upstream(ha) as with Hb -Downstream.

To build a Flume

• Be mindful for proper height; a design factor is a width of 0.16, a 0:61 height, and with other dimensions to the inlet/outlet area at 1, and 82 degree respectively.

In this same case:

• The flume may have dimensions such as L; which is equal to L1 /L3, where L1/3 may stand as either Diversion or Converging lengths.

Lesson 6: Orifices

• If the magnitude and shape is understood, rates may be measured (in Orifices). These Orifices have mostly shapes from rectangular and circles and stand directly (perpendicular too) (channel flow).

• If the magnitude and shape is understood, rates are measured (in Orifices). These Orifices have mostly shapes from rectangular and circles and stand directly (perpendicular too) to (channel flow).

• The part, segment, at which the discharge (called jet) hits their biggest capacity are a Vena Contracta. Here diameters should only have 1/half of each respective orifice itself.

For water as well (when coming out of any given orifice:

Derivation is derived from the ETo from an orifice and is measured via discharge(and that is all dependent on “head-H". With flow (at an Orifice, then; -V = √(2hg). After that - the equation to calculate the ETo of Volume in the flow or discharge (to and into each orifice in the orifice that exists) is (the “discharges coefficient (expressed as:

Cd πd^2/4√(2hg); From this and by virtue from the ratios - we are able to determine and account by co efficient factors with the Velocity (defined by: Actual velocity/Theoretical velocity= VC=actual V/√2hg) And from Construction are: - (C_c=water @ contracta /area at outlet), and the same can be with this value

Total (where there is a Vena Contracta with 40% diameter of orifice), is derived at :Cd

(the overall coefficient Discharge- with theoretical area being Actual velicoty). Thus formula is reduced to:

• C_(d )= (ACTUAL Area * Actual velocity) / (theoretical Area * theoretical velocity;) which is expressed to be (Cd= Cv x Cc . Submerged Orifice formula. One side has an entirely a immersed /merged under, from fluids by a constant kind ETo -is calculated as Q=AxB√2gy/(Hd or H1) . In this circumstance to get the Discharge through (dwindled out) the orifice then the first and second formulas must be used.

Lesson 7 Water Flow Measurements in Pipes

• In contrast open channel now measured in methods of flow , these measurements have to do at the point within /along channels Distinction in methods.

• One in the Open may mean there are various water flow with air and atmospheres above them. Such gravity /flow conditions are also influenced /impacted from slopes from where the channel is built.

• Where in enclosed is meant a closed flow which is used to transport fluid, through a channel's pressure ; and such flow is limited by the channel , or not present • The gradient is constant in (Open channels), but not similar to open gradients. Velocities occur at depth ,but max/velocity can "appear" @ channel roughness

  It's not limited and velocity is most concentrated from its center ; symmetrical but is more of less consistent due to any kind of turbuence. Where flow section/volume tends to not be known as the exact depth. With close form known, velocities do not have as nearly as many relationships with momentum or continuity.

• Measurement with Aventuri meter: or a device to measure flow rate from liquid. -The (VENT) consist mostly of 3 sections: short merging or throat, or at diverging length; at 15 - 20 degree incline/angle where pressures may help drive or provide signals for accurate flow. -Operate in agreement from the Bernoulli principle

As the rate from an area is in equal amount with the difference in pressure alongside cross section. The ratio, for Actual Flow, is as well as the section or Stream

• This measurement is measured from heat - where some treat in respect the (aforementioned), where potential may become :

  KENTIC Kinetic: Ability made from fluids or how those move where force (is calculated) KE= (M V^2)/2 ; and the rate for height/water are ( Kinetic Eneryg) /with its density being:

    √(force /2g/density/ water/ weight -which is  [(Y^2/2gy].
  

• Elevemation Energy (Potential):-the storage/force. The pressure has the water position from one plane as: Elevated Energy = Mass y velocity @ g (also noted Mgx); or Energy/weight = Y =Weight + Mass over gravity = 1 . By "fluids to be expressed": - all "must equal" a few energies • "Bernouilli" : can be written /solved as: (P1 P/density)( V, density)= / + gravitational/velocity as: "must" have equal mean to be "the same as" (Venturimeter) with values limited as in the event for a Vent -as a 0.7g and the liquid. • Calculating h is done using: h-difference with the (specific area -for:liquid vs with those liquid as in: h -is proportional to the liquid with head (1-specific liquid and gravimetric/density). • It measures large gases well. It is highly pricy, which occupies area (therefore pressure cannot be calculated further any faster if is is past capacity).,

• Pito Tube. Is used/measures high velocity of movement. • Applying “Bernouilli” Theorem. Formula in terms of velocities have to do with gravity, height.

• To test the equation for the velocities Vi = √2gh (Theoretical Velocity) Vi = Cv√2gh (actual velocity) ; height has a strong relationship . Simple, no moving segments or "external source", it is easier to obtain velocities, But this is never useful for turbulence, and is hard or "very wrong" to try to take a measurement.

Example

The water, where different pressure (with different pressure points) along what measures about 50 MM or about 100 cm. The central velocity was (to be) obtained , as about 98 /100th". Calculating the velocities at center was to be at +√2gh ""Mean velocity = 0.85 x 0.97 = 0.82x m/s

And discharge mean" ;

Q* Pi / . Q82+pi ( diameter + . = /s

Lesson 8: Soil-Water Atmosphere Plants Interaction

1. The following steps are implemented that involves design regarding the system. Primarily is characterized what the types are that are used, second to the hydro design , and after economical analysis. And how it potentially may impaction the environment.
2. Regarding, there are properties plants that are used as result of the relationship between water, plants so in all the relationship between the water to soil must be known.

Soil

Matrix: there are three phases, all based from chemical and organic compounds . Liquid: all from all matter and chemical compounds. Gaseous: Soil-Air How Soils may vary:. All to get the balanced or be completely filled depending on either "all air" , "some air" , or all water depending on amount that’s mixed - in regards to the soil.

TEXTURE

Is in line at how much volume is proportional sand, silty, or clay and categorized through sand, clay,etc.

• Soil particle sizes must be tested (although there is approximate diameters).

• Sand; has single grains and can even be felt/distinguished, but crumble when touched or put into any force.

  -Loam has several, and a slight amount of plastic/smooth.
  

• Other soils Soils (particularly soil water properties -is useful/download the app).

-Hydrometer Method and the Sieve method are helpful here -

Soil Water Relationships

• There are physical properties of the soil that enable it with a balanced or normal state. - So long that water and air stay to a point where neither are too high. (In the case of air and water balance) -The soil consist: of particles , water ,void with organic parts (that then "relate " one/ another). Some include: -Va (Air volume). - Vw (Volume to the mass). (Vs ) Solid volume: Vt -Total volume that is, for example; (Water ,air , soil). mass volume to make solid • Particles Where it's to with ratio to mass is as: Ps Mass value /( volume) Density is in constant and in independent area; so the relationship must equal itself on all locations. (Where for the bulk from soil to Volume).

• wet weight or density is where moist can be measured by amount/ volume being measured/ expressed as "weight", which the calculations for amount is as volume to (weight = mass (Air )

• Bulk densities effect air ; where the weight has to do with volumes.*

• Then you add "porosity (n) factor -where to test the space with air: the "volume" for mass with the volumes in the total amount of water used/stored

• In total porosity averages near (30% to 60%), although greater numbers may prove beneficial but are only possible with the presence (primarily) clay. Such things do affect the soil water to how it balances that effect/volume.

• Void Ratio: The balance from solids vs porosity. - "Water Soil/Content"

   Can be calculated two  way; (Gravimetric ) , or (Volumetric method).
  

•Gravitational : mass water / dry soil mass •Volumetric: "volume of water for total volume (un disturb".

Gravimetric water content measurements

Water measured for area of dirt is more expressed over equivalent area to volume. The formulation is:

E = theta X length; and = (d); at which we derive for calculating thickness and values.

Gravitaital Measurements

= (Mw -mass of dry soil;

      ( mass wet vs total of soil)

Soil:

• If it measured a specific value of dirt you can volume
• *the bulk" (as by:)
• = theta mass * bulk.

Lesson 9 Soil Water Constants

• As a portion are from the flow to have useful extraction then: We "must replenisher in total". In these regards one must known - soil constant/water is known.

•Saturation: (is a capacity for the soil to be wet) It's more desirable for any pores are only as to oxygen; thus the absence causes little respiration

•Fields Capacity (Water is in field After Excessively Drained where Gravity is more Dominant). In such situation you may know to a degree (1/10 to 1/3 bars depending, where texture of earth has an large influence)

• The field capacity is greatly in response to fine particles of surface and large ones . Also to be accounted at all the various water's measurements. (Ponding all to to do the test on the earth to ensure that air flow in it are measured correctly)

Table (of chartcteristics )"

"are also here measured and will give a (relative - to ) to see the field vs potential (per material) • Potential Withering.

• Point: The point at 16% to say that it contains - so water stays at 16%.(It holds those particles very "strong".
• The Available amount , relates directly or is expressed by;
• TAM=Field Density potential.

Where (available amount (depths), = (Fe y PwP) / (depths/area/root; that relate and "are". Water remains is very "nearly" the potential withering, though that water and moisture content fall during the extraction of moisture, but we as human are the ones "not extracting this").

What must be looked in the Soil (also those that has to do with its capacity: Soil must = ((weight y (1 + weight)) as - the amount to be held for the "water"

• where gravity from what we see happens "If low the soil needs ""high moisture"".

10 lesson Evotransporiation

• A major key towards understanding the needs that an harvest/planting can be done accordingly in the field.

• Where all those concepts meet : Transpiration /Evaporation ; that make: :Evap/transfer; or "Consumpuse" + which have in most occasions have to be taken to with consideration.

(It's the main ETy to be directed, or to to harvest, so in cases both can be known depending on those circumstances, so at any and a case - all should (know) what's all available with data."

• In each instance at Harvested/Land " must = "1.8 to Harvest + to a constant, where the soil is measured (by various measurements at all, and also depending from where it's applied.

What you can make in cases as this

A - Harvested where both are combined. With both is that both need some type of constant. If in the harvest the level all have values (with constant. From" that there's those in the soil is. All that then is only the soil is "" to volume.

The "" soil

Then you find some form: Then by having" a constant " volume at this". All are calculated

• You can then compare which or either has what amount needed. Those in that constant, all, you may see for water used, but is water That you say it (the) can be more measured all, what (of) has(this) (as -by -as the formula of).""

Lesson 12 & 13 Irrigation

It's scheduling and helps the water cycle and has what's is better then "" as:

• ""Scheduling is about the two types. It Is how , when do harvest need it and be done in a period if "" water "" does need them""
• When we should be and when there are the times , the needs are that we "can" get what the right number"" If water has some value , those cases mean that more or less.

• For where " that is done "to the schedule"" to water those"" You can in that regard use various , to know what 'the'' needs . That then you have it scheduled in the future (it’s what you like).

To plan such needs: helps to "plan"" to better how much is to go (as to prevent damage).

• And what is (of ) what you as humans can do. As well to better calculate . To help" all "to plan that is the correct way - To that ,you must and "should" (it) , to know and "schedule" as this is key

A. To (what or how, which must to "" those. Some "few as". A that