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report on water supply engineering
INTRODUCTION
Public health engineering has nowadays emerged and has been realized as a profound discipline under Civil Engineering as it directly deals with the overall health and consequently the well being of the society itself. In spite of the fundamental civil engineering skills, it urges for an equal stuff of knowledge of chemistry, biochemistry and biology as well.
On the other hand, water supply engineering, which is a part of public health engineering, deals on the optimization of some very basic parameters like quantity, quality, stability, cost and reliability out of which quality is perhaps the only parameter that could be widely maneuvered at the desire of the engineer. And so straightforward is the fact that the engineering is always concerned in providing the water of quality at its best. For this a sound assessment of water quality is the prerequisite which could be enhanced through the determination of physical, chemical and biological properties of water, obviously through experimentation. Hence the laboratory experiments do posses a very significant role in water quality analysis.
Having realized this, the augmented practical experiments have been incorporated in the curriculum of BE Civil, 3rd year , 1st part of IOE. Scheduled relevant experiments had been conducted in the laboratory Whose report is presented as that follows.
Experiment no: 1
PHYSICAL PROPERTIES OF WATER
OBJECT:
TO DETERMINE THE TEMPERATURE ,COLOUR ,Ph AND TURBIDITY OF WATER SAMPLE.
SCOPE:
Physical properties like temperature and Ph may not be directly as offensive as colour and turbidity for a layman consumer but they indicate the prevalence of ongoing biological , chemical and bio-chemical changes in water and govern the treatment method to be developed. Turbidity and colour are not appealing to the consumer as well as indicate the quality of water etc. Temperature ,colour ,pH and turbidity are the properties(physical) of water ,which are examined for, in beforehand deciding for any further examination, treatment or else.
APPARATUS REQUIRED:
1. Beaker
2. Thermometers
3. Griffin digital pH meter
4. Reference electrode buffer solution pH=4
5. Platinum-cobalt standard(or Hazen)colorimeter
6. HACH turbidity meter
THEORY:
Temperature:
Temperature is the measure of degrer of hotness or coldness. Temperature in water may affect chemical ,biological and bio-chemical reactions in treatment, and an appreciably high temperature indicates the prevalence of biological activities, provided water is not from juvenile aquifers. The consumption of food stuff, growth, reproduction and other metabolism could be check by lowering the temperature. Temperature also affect the reaction rates and
solubility of chemicals. The solubility of gases also decreases at elevated temperature. Temperature also affects the physical properties like viscosity and density(hence the rate of sedimentation), surface tension etc of water.
The desirable temperature of water is 100C to 150C. While water at a temperature above 250C is considered to be objectionable, that exceeding 350C is declared unfit for civic supply. Measurement of temperature is done with the help of thermometer.
Colour:
colour is caused by organic material in solution or a colloidal state and should be desinguished from turbidity, which may cause an apparent colour. True colour in water supply is generally cauded by dyes derived from decomposing vegetation. Waters from swamps or weedy lakes and therefore most likely to be troublesome on this respect. Coloured water is not only undesirable because of consumer’s objections to its appearance, but may discolor clothing land adversely affects industrial processes. The desirable unit is 5 to 25 Hazen units. Colour is expressed in colour units and is measured by comparison to a platinum-cobalt standard: if 1.245 gm of platinum and 1gm of cobalt are dissolved in distilled water and diluted to 1 liters, it has a colour of 500 Hazen units.
pH value:
The presence of acidity alkalinity of water is quantified in terms of pH. The pH value indicates hydrogenIons concentration in water. The water found in nature may acidic or alkaline depending upon the nature of dissolved minerals and sometimes salt . When acids or alkalis are dissolved in water, they dissociate into electrically charged ions of hydrogen (+ve) and hydroxyl(-ve). pH of a solution is the negative of common lagarithm of hydrogen concentration. For neutral water,
[H+] = 10-7
pH = log10[ 10-7] = 7
pH scale explains variation of types of acidity and alkalinity on pH scale. pH values of 6 to 8.5 should be kept for public water supply. Lower value of pH may cause corrosion etc and higher value may produce encrustation, sediment deposits, and difficulty in chlorinating etc. pH measured by Griffin pH meter against standard buffer of known pH.
Classification of water according to pH
pH 1-3 : acidic
4-6 : weak acidic
7 : neutral
8-10 : weak basic
11-14 : basic
Turbidity:
The turbidity of water is caused due to the presence of suspended and colloidal matter in water. Turbidity is a measure of the extent to which light is either absorbed or scattered by suspended material in water. Turbidity in water results from materials such as clay, silt, rock-fragments, metal oxides from soils, vegetable fibres. Microorganism etc and hence indicate the same.
It is expressed in parts per million (PPM). The turbidity produced by one milligrams of silicon dioxide(SiO2) in one liter of water is the practical unit of turbid. If 1 mg of SiO2 is dissolved in a liter of distilled water, the obstruction o flight thus produced is referred to as one Jackson turbidity unit or Nephelometric turbidity units (NTU).
OBSEVATIONS:
The physical properties of different samples of water are as below:
a₎ Turbidity :
raw water =20NTU
boring water=5.2NTU
distilled water=4.5 NTU
who standard=5NTU
Nepal standard=5-10
b₎ pH:
sample water=7.7
Nepal standard=6.5-8.5
c₎ temperature=140c
d₎ colour= 500hazen
CONCLUSION:
Having analysed the given sample water (of unknown source), the parameters of temperature ,colour, pH and turbidity had been measured. A brief outlook on the data obtained suggests further analysis for chemical and biological parameters followed by suitable treatment, if the water to be distributed for civic supply. Hence the experiment was successfully completed.
Experiment: 2
THE JAR TEST
OBJECT:
TO DETERMINE BT THE EXPERIMENT THE OPTIMUM DOSE OF GIVEN COAGULANT [ Al2(SO4)3 18H20,alum] BY JAR TEST
SCOPE :
Sedimentation by coagulation is a subtle method of removing dispersed colloidal impurities, however the dose of coagulant heavily depends on water quantities parameters like pH ,temperature ,quantity (type) and quantities of colloidal themselves and so on and so forth thereby rendering difficulty to calculate exact dose by analytical means. Therefore , the jar test is widely used to determine ,by experiment ,the optimum dose of coagulant.
APPARATUS REQUIRED
1. Given water sample -500 ml
2. 1% [ Al2(SO4)3 18H20,alum] solution
3. Floc tester
4. Dash mixer
5. Magnetic stirrer
6. 500 ml jar
7. 1ml &2ml pipettes
Theory:
Settling velocities of colloidal and very fine particles are so small that removing them in settling tanks is almost impossible under ordinary conditions , yet this could be greatly expedited by the addition of certain chemicals called coagulants which when thoroughly mixed from insoluble gelatinous masses of flocculate precipitates which enmesh the colloidal and fine suspended particles which become heavier and settle down. This process of reaction is called coagulation.
The most common coagulant in use is alum . it requires the presence of alkalinity in water to fem the floc . When dissolved in water , aluminum sulphate tends to hydrolyze, in alkaline media into Aluminum hydroxides as is evident from the following reactions
Al2(so4)3 .18H20 +3Ca(HCO3) → 2Al (OH)3 + 3Caso4+18H20 +6C02
0r, Al2(so4)3 .18H20 +3Ca(0H)2) → 2Al (OH)3 + 3Caso4+18H20
0r, Al2(so4)3 .18H20 +3NaC03 → 2Al (OH)3+3Na2SO4+18H20 +6C02
Aluminum hydroxide is insoluble precipitate. Alum is found to be most effective between pH of 6.5 to 8.5.Its dose depends upon various other factors like turbidity ,color , pH temperatures etc . The common test, which is performed to determine the optimum quantity of coagulant ,is known as the jar test.
OBSERVATIONS:
Physical properties of water before jar test:
Temperature =140c
Color =500H
pH =7.7
Turbidity =20 NTU
The observation and derivations are tabulated below:
Jar 1 2 3 4 5 6
Dose in the dash mixer(ml) 0.5 1.0 1.5 2.0 2.5 3.0
Concentration of alum(mg/l) 10 20 30 40 50 60
pH 7.3 7.1 7 6.9 6.8 6.7
Turbidity 9 7 5 7 6 10
After the completion of test:
Best floc formation and consequent settlement in the jar no 4 whereby dose mixer=1.5 ml of 1% alum=30 mg/l is the optimum dose of the coagulant.
CONCLUSION :
It is noteworthy that the dose exceeding the optimum dose hence obtained had not been successful floc formation because there is abundance of negative charge due to overdose and thus the floc ,that had already formed too, disintegrates . Thus by finding out the optimum dose of the coagulant as 30mg/lit of alum the jar test was successfully completed . The water after jar test obtained was within the limits of WHO standard for drinking purpose.
Experiment no: 3
DISSOLVED OXYGEN
OBJECT:
TO DETERMINE THE DISOLVED OXYGEN (DO) IN WATER SAMPLE BY WRINKLER METHOD.
SCOPE:
A certain amount of dissolved oxygen is essential for aerobic decomposition of wastes to avoid nuisance conditions in rivers and to maintaining the growth of fish and other aquatic animals. Dissolved oxygen determination is also required as a part of BOD test and estimation of corrosion . Oxygen enters natural waters by gas-exchange phenomena through air water interfaces. The amount that can be dissolved depends on turbulence ,temperature and partial pressure of the gases in contact with water. The modified Wilnkler’s procedure used to estimate the dissolved oxygen.
APPARATUS USED:
1.Titrating apparatus
2. Dissolved oxygen sample bottle
3. Conical flask
4. Reagents used:
i. Sodium iodide
ii. Concentrated Sulphuric Acid
iii. N/80 sodium thiosulphate(f=.000)
iv. Starch indicator
THEORY
The basic theory of Wlinkler’s method is outline as follows in conjuction with the sequential procedure.
After taking 300ml-sample water bottle,2ml of Manganese Sulphate followed by 2ml of Alkali- iodide –Azide are to check whether there is any dissolved oxygen or not. If there is any DO present, violet color is imparted due to the formation of Manganese hydroxide. The azide helps remove Fe,Ni etc which otherwise interfere to hinder oxygen release. The chemical reactions are:
2MnSO4 → 2Mn + 2SO4
2NaI + 2NaN → 4Na + 2I +2N
4Na + 2H2O + 2O → 4Na + 4OH
2Mn + 4OH → 2Mn(OH)(violet)↓
4Na + 2SO4 → 2NaSO4
2Mn(SO)4 +2(NaI +NaN) +2H2O + O →2NaSO4 + 2Mn(OH)2 + 2I + 2N
As evident hereby from the chemical reaction ; iodide is released for the dissolved oxygen (one part iodide for one part of oxygen ).
After allowing the precipitates to settle , sulphuric acid is added to furnish positive hydrogen ions so that iodide ion is liberated as free iodine as apparent from the following chemical reactions;
2H2¬SO4 → 4H + 2SO4
2Mn(OH)2 + 4I +4H → 2Mn + 2I +4H2O
2Mn + 2SO4 → 2MnSO4
2Mn (OH)2 + 4I m +2H2SO4 → 2MnSO4 + 2I +4H2O
Out of the sample that has undergone through above procedure , 100ml is titrated with (N/80; f=00) Sodium thiosulphate till pale straw colour . Then starch is added and titrated slowly for the removal of blue colour.
I + Na2S2O3 → Na2S4O6 + 2NaI
Since one volume of iodine (hence one volume of oxygen) consumes two volume of sodium thiosulphate and if V be the volume of thiosulphate consumed ;
D.O. concentration =(V/2*f)mg/liters
Where C.F. is the correction factor with regards to the inexact normality of thiosulphate solution.
OBSERVATION :
Concentration of hypo solution =N/80(f=.881)
No of observation Initial Burette reading
ml (A) Final Burette reading
ml(B) Amount of thiosulphate
ml (C),f=.881
1. 0.0 2.4 2.4
2. 2.4 4.8 2.4
3. 4.8 7.2 2.4
D.O. concentration =(B-A) * f mg/liters
= ( 2.4 )* .881 mg/liters
= 2.1144mg/liters
CONCLUSION:
Thus by determining the DO concentration as 2.1144 mg/litres , the experiment has been succefully completed . According to WHO standard the DO in water for drinking purpose should be in range of 6- 14 ppm and if less than 4 ppm it is rejected and left for more aeration.
Experiment no : 4
SUSPENDED SOLIDS AND TOTAL SOLIDS
OBJECT:
TO DETERMINE THE AMOUNT OF SUSPENDED AND TOTAL SOLIDS IN THE GIVEN SAMPLE OF WATER.
SCOPE:
Suspended solids in water chiefly constitute of the organic and inorganic materials ,which imparts turbidity and contribute to deteriorate the water quality by providing absorbing media for chemical and biological agents. Hence determination of the suspended solids helps to decide the needs of further analysis or the mode of treatment scheme.
APPARATUS REQUIRED:
1. Funnel
2. Beaker
3. Membrane ( glass microfiber) filter
4. Oven
5. Desiccators
6. Sensitive balance (0.001 gm sensitive)
7. Porcelain basin
THEORY:
Suspended solids in water may consists of inorganic and other solid constituents as well as plant fiber ,biological germs etc. Suspended solids are measured in mg/ltr or PPM of the water sample. The suspended solids parameter is used to measure the quality of water to monitor the treatment process etc. Suspended solids are aesthetically displeasing and provide the good absorption media for chemical and biological agents. Suspended organic solids may be degraded biologically resulting in objectionable byproducts. Biologically active suspended germs may include disease producing organism etc. Surface water contains more suspended matters than ground water. Total solids include the solids in suspension ,colloidal and dissolved form . The quantity of dissolved and colloidal solids in a water sample is determined by evaporating the filtered water obtained from the suspended solid test and weighing the residue .
The basic causes and effects of the suspended solids is tabulated as follows;
No Causes Effects
1. Silt , clay ,mineral ,
organic , matter Turbidity ,color, odor, taste aesthetically offensive
2. Protozoan ,algae ,fungi Color, odor ,turbidity , disease
3. Pathogenic bacteria Related disease ,often epidemics
OBSERVATION:
Amount of suspended solids :
Weight of the dry filter paper = 0.6036 gm
Weight of dry filter paper with suspended solid =0.7038 gm (100 ml water)
Weight of suspended solid, A = 0.1002 gm
Volume of the sample water ,V = 100 ml
Suspended solid content in the sample (mg/Lt) = 0.1002/100 *1000*1000
= 1002mg/ltr
Amount of total solids:
Weight of empty porcelain basin = 49.5003 gm
Weight of porcelain basin with total solid = 51.8434 gm(50 ml of water)
Amount of total solids = 2.3431 gm
Total solids content in the sample (mg/lt) = 46862.0 mg/lt
Now,
Dissolved solid = total solid –suspended solid
=46862.0 – 1002
=45860.0mg /lt = 45.86 gm /l
CONCLUSION:
The amount of suspended solids was found to be 1002 mg /lt , the amount of dissolved solids was found to be 45860 mg /l and the amount of total solid was found to be 46862.0 mg /l. The amount of solids found are very high this may be due to taking highly turbid water sample.
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a report on hydrology
Engineering Hydrology
Hydrology means the science of water. It deals with the occurrence, circulation, and distribution of water of the earth and earth’s atmosphere. In a general sense, hydrology is a very broad subject of an interdisciplinary nature drawing support from applied sciences such as meteorology, geology, fluid mechanics, physics and statistics.
Hydrology is classified as –
1. Scientific Hydrology which is concerned with academic aspects.
2. Engineering Hydrology which is concerned with its engineering applications.
Engineering Hydrology deals with
- Estimation of water resources
- Study of processes such as precipitation, runoff, evapo-transpiration,etc
- Study of problems such as floods, droughts and strategies to combat them.
Sources of data
The main components of hydrological cycle are rainfall, evaporation, Transpiration, Infiltration, Runoff and Ground water. Depending upon the problems in hand, a hydrologist would require data relating to the various relevant data such as:
A. Weather records – Temp, Humidity, wind velocity
B. Precipitation data
C. Stream flow records
D. Evaporation and transpiration data
E. Infiltration characteristics of area
F. Ground water characteristics
G. Physical and geological characteristics of area
General Knowledge of the measurement and reading of these data and the instruments used for their measurement is of great importance in Engineering Hydrology.
CALCULATION OF DISCHARGE AT LAB
Time (sec) Revolutions Revolution per second
20 15 0.75
25 19 0.76
30 25 0.83
60 48 0.80
The mean rev/sec is 0.786
Given
V=0.7002*Ns +0.0004
So, the required velocity is 0.55076 m/s
Area=0.1791*0.300= 0.0537 m2
The required discharge is A*V =0.0296 m3/s
FIELD VISIT OF METEOROLOGICAL STATION AT KHUMALTAR
The study of hydrology necessitates the collection of data on humidity, temperature, precipitation, radiation, evapotranspiration and wind velocity. For the collection of these meteodata, number of meterostations are fixed around the country. Around 400 meterostations are presently operating in our country.
The station we visited at Khumaltar, Lalitpur was an Agro-meteorological station. It is one of the 14 major stations in Nepal. This metreostation operates under Department of Hydrology and Meteorolgy, Nepal. The various equipments and instruments we studied at this station were:
1. Rain gauge
- Symons’s Gauge ( Non-recording Type)
- Tipping Bucket ( Recording Type)
2. Anemometer
3. Campbell Sunshine Recorder
4. Evaporimeter
5. Steven Box ( Psychrometer)- Thermometers for measuring Min & Max temp. and Relative Humidity.
The study tour was conducted on 14th January 2011. The summary of Study conducted is as described in following.
1. Rain Gauge
Rainfall is expressed in terms of the depth to which rainfall water would stand on an area if the rainfall was collected in it. The rainfall is collected and measured in a rain gauge.
A rain gauge essentially consists of a cylindrical vessel assembly kept in the open to collect rain. Rain Gauge is broadly classified as:
i. Non – recording Rain gauge
ii. Recording Rain gauge
( I ) Symon’s Gauge ( Non-recording Gauge)
Symon’s Gauge consists of a circular collecting area of about 12 cm diameter connected to a funnel. The funnel discharges the rainfall catch into a receiving vessel. The funnel and receiving vessel are housed in a container. Water contained in the receiving vessel is measured by suitably graduated measuring glass with accuracy upto 0.1 mm.
Fig: Inside cylinder of Symons’s gauge Fig: Symons’s Gauge
( II ) Tipping Bucket rain Gauge( Recording Type )
It can give permanent automatic rainfall record without any bottle reading. There is mechanical and electrical arrangement by which the total amount of rain fallen gets recorded automatically on a graph paper. The gauge thus produces a record of cumulative rain Vs. time in the form of a graph which is known as mass curve rainfall.
Rain water is first caught in a collector and is funneled into a two compartmental bucket of 0.25mm each. These buckets are so balanced that when 0.25mm of rainfall collects in one bucket, it cannot withstand more and tips round to bring the adjacent one in collecting position. The water from tipping bucket can be collected. Further while tipping it actuates an electrically driven pen to trace a record on clock work driven chart. This instrument can also digitize the output signal as seen to the automatic data logger.
Fig: Tipping bucket with Automatic Fig: Tipping Bucket (Inside)
Data logger
2. Campbell Sunshine Recorder:
Campbell Sunshine recorder is used to measure the duration of bright sunshine hours which mainly depends on the latitude of the place and environment. The main principle of Campbell Sunshine recorder is that when bright sun rays are converged using a lens into a paper it gets burnt. The special paper used is known as Campbell Sunshine card.
Campbell Sunshine recorder consists of a special arrangement of transparent spherical lens provided with hourly graduated paper (Campbell Sunshine card). The sphere is faced directly towards the sun by fixing the latitude of place. The card is concentrically mounted with the sphere.
Continuous burnt line on paper represents continuous sunshine and as paper is graduated for time in hours, the no. of hours can be determined.
The glass sphere is usually 10cm in diameter. The card is held below the sphere in any one of the three grooves depending upon the seasons of the year. There are different cards for different hemispheres of the earth as well as different card for various seasons:
In northen Hemisphere, 3 kinds of cards are generally used:
1. Winter card ( For 15th October to 29th February)
2. Summer card ( For 12th April to 2nd September)
3. Equinox card (For 1st March to 11th April & For 3rd September to 14th October)
Fig: Campbell Sunshine Recorder Fig: Campbell Sunshine card
3. Anemometer
Anemometer is used for measuring th speed and direction of wind. The speed of wind varies with temperatures, pressure and altitude. There are two horizontal arms over which the instrument for measuring direction and magnitude are mounted. Direction of wind is usually expressed in terms of 16 compass points (N, NNE, NE, NEE, E, SEE,…)
The anemometer used was a three cup anemometer with a vertical axis of rotation.
Anemometer converts the rotational speed of the cups into linear speed. The speed of wind is measured in km/day in the particular anemometer. It was placed 2m above the ground surface.
(Determinination of Direction) (Measurement of Magnitude)
Fig: Anemometer
4. Steven Box:
Steven Box consists of special arrangement of 4 thermometers with a view to determine the maximum & minimum temperatures and Relative Humidity.
Two small clips are placed inside the thermometers to measure the maximum and minimum temperatures. When the temperature gets to the minimum, the mercury remains at the same position even if temperatures rises (In case of minimum thermometers) whereas in case of maximum thermometers its exactly the opposite. When the mercury rises to the maximum temp, the mercury remains there and hence maximum and minimum temperatures are recorded.
For the measurement of relative Humidity, two thermometers were placed vertically. One of the thermometer’s bulb was wrapped around a wet cloth and the bulb of the other was kept dry. These two thermometers’ combination is also called psychrometer. Wet bulb loses water from the cloth constantly due to evaporation due to which the temperature of this thermometer is lower than dry bulb temperature. The rate of capillarity in the cloth depends upon Relative Humidity.
Wet bulb Deficit or Wet Bulb depression is the difference in temperatures of these two thermometers.
Fig: Steven Box
5. Soil temperature measuring thermometers:
As Khumaltar is an agro-metero station, the instruments for agricultural as well as meteorological data collection are present. The thermometers installed for soil temperature measurement are important especially for agriculture. But the amount of energy received or lost by the soil is determined using these thermometers. The 4 thermometers can give the temperatures of the soil at 10cm, 20cm, 30cm & 40cm.
The variation of temperature with depth is different during different parts of the day. During summer: In the morning, the temperature at all the depths is nearly equal. As sun rises in the afternoon, the temperature at the surface is highest while the temperature inside the soil gets cooler. But in the Evening, outer atmosphere cools hence cooling the surface and temperature at the surface are lower than that at the bottom.
Fig: Thermometers for soil temperature measurement
6. Evaporimeter
An Evaporimeter is used to measure the evaporation rate and hence estimate the approximate rate of evaporation from a natural water body. Evaporimeters are large water containing pans which are exposed to the atmosphere. If rate of evaporation is to be determined using an evaporimeter, other meteodata such as humidity, wind movement, air and water temperatures and precipitation should be noted on a regular basis as these parameters affect evaporation significantly.
Evaporation rate = ( Evaporated volume) / Time taken to reduce the depth
Evaporimeters are generally placed at a height of 15cm above the ground so as to allow free air circulation and on wooden blocks so that heat transfer by conduction can be checked effectively.
Evaporation pans are not the exact models of reservoirs and posses some drawbacks. So there is a pan Coefficient. (Cp)
Lake evaporation = Cp x Pan Evaporation
Fig: Evaporimeter
7. Radiometer:
Radiometer is an instrument which is used to measure the net radiation. It gives the net radiation by subtracting short wave and long wave. It is also known as pyranometer.
Fig: Radiometer
8. Automatic Data log
It is an automatic device to record wind speed, rainfall, direction of wind, air temperature and solar radiation. In tipping bucket, every tip is recorded in this Data logger, the value of solar radiation, the velocity of wind, etc are also recorded. (For Figure Ref. Tipping bucket)
Conclusions and Discussions
With this field visit, we had a chance to be familiar with the different hydrological parameters measured in meterostations and the instruments & equipments used to measure these parameters.
The different hydrological parameters measured were – wind velocity, R.H. of air, Rainfall intensity, Sunshine duration, Soil Temperature, Air temperature, Evaporation etc.
Discharge Measurement
The measurement of discharge in stream forms an important branch of Hydrometrics, the science of water measurement. In the hydrological cycle, streamflow is the only part which can be measured accurately. A stream is a flow channel into which surface runoff from a specified basin drains. After visiting the Khumaltar Meteostation we went off to Nakkhu Khola for its discharge measurement.
Discharge measurement was done by velocity area method. Floatation method was also done for velocity determination.
Velocity-Area method:
This method of discharge measurement consists essentially of measuring the area of cross-section of the river at a selected section called gauging site and measuring the velocity of flow through the cross sectional area. This method is the most practical method of measuring stream discharge.
In this method, the width of the stream is divided into a number of increments. The following are some of the guidelines to select the number of segments:
1. The segment width should not be greater than 1/15 to 1/20 of the width of the river.
2. The discharge in each segment should be less than 10% of the total discharge.
3. The difference in velocities in adjacent segments should not be more than 20%
But most of the time all of these conditions cannot be fulfilled so we must take steps according to the site condition.
For velocity measurement, for shallow sections, it is measured at 0.6 of the distance from the water surface to streambed whereas for deep sections, the average velocity is taken by measuring velocities at 0.2 and 0.8 of the distance from the water surface to streambed.
The product of velocity, depth and width of the section gives sectional discharge. The total sum of the sectional discharge is the total discharge of the stream.
Q= A x V
Where, Q = discharge (m3/sec)
A = sectional area ( m2 )
V = velocity (m/s)
To measure depth, for shallow streams, height-calibrated rod can be used whereas for deep streams and for accurate depth measurements electro acoustic instrument called echo-depth recorder is used. Velocity is measured using current-meter so this method is also sometimes called standard current meter method.
Current Meter:
The most commonly used instrument used in hydrometrics to measure velocity is a current meter. It consists essentially of a rotating element which rotates due to the reaction of the stream current with an angular velocity proportional to stream velocity.
There are two types of current meter:
1. VERTICAL AXIS CURRENT METER
The vertical axis meter consists of a series of conical cups mounted around a vertical axis. The cups rotate in a horizontal plane and a cam attached to the vertical axial spindle records generated signals proportional to the revolutions of the cup assembly.The disadvantage of such meters is that these are useless in situations where there are appreciable vertical components of velocities. The accuracy is higher in higher velocities than in smaller ones.
2.HORIZONTAL AXIS CURRENT METER
The horizontal axis meters consist of a propeller mounted at the end of horizontal shaft and these rotate in vertical plane w.r.t. horizontal axis.These meters are fairly rugged and are not affected by oblique flows of as much as 15°.The accuracy of the instrument is about 1% at the threshold value and is about 0.25% at a velocity of 0.3m/s and above.
The current meter is so designed that its rotational speed varies linearly with the stream velocity at the location of the instrument. A typical relationship is given by,
V = aNs + b
Where,
V = velocity of flow in m/s
Ns = no. of revolution per sec of the current meter
a and b are meter constants given by the manufacturer, or generally determined by experiments. We used vertical axis current meter for velocity measurements.
Fig: Measuring rod, Current meter
2. Float Method:
A floating object on the surface of the stream when timed can yield the surface velocity by the relation,
Vs = S/t
Where,
S =distance traveled in time t.
This obtained velocity Vs when multiplied by the cross sectional area A of the stream along the mid point of the S distance gives the discharge Q using the relation:
Q = Vs*A
This method of finding velocity and hence discharge finds applications in special circumstances although is primitive method: ( I ) a small stream in flood ( II ) a small stream with rapidly changing water surface and (III) preliminary surveys and also for checking purposes.
There may be surface floats (simple float moving on the stream) or there can also be the Rod Float, in which a cylindrical rod is weighed so that it can float vertically.
Field Procedure:
- After fixing the gauging site, a distance of 10 m. both upstream and downstream was measured along the centre line of the river. Two people stood at the two extreme points of the 20 m. length.
- Then a surface float was allowed to flow through the above marked 20 m. and the time taken to do so was measured using a stop watch.
- The process was repeated as per required.
Observations and calculations:
The time taken by the float to flow 20m along flow direction,
S.no Time(sec) Distance(m) Velocity(m/s)
1 104.84 20 0.191
2 118.73 20 0.168
3 100 20 0.2
Mean velocity of flow at mid line of flow in stream (v) = 0.186 m/s.
S.no Distance(m) Depth(cm)
1. 0 0
2. 0.5 10.2
3. 0.5 10.1
4. 0.5 10.3
5. 0.5 10.9
6. 0.5 10.7
7. 0.5 9
8. 0.3 0
The cross sectional area at the midpoint (A) = 0.297m2
Thus, discharge of the stream (Q) = 0.8*V*A
= 0.8*0.186*0.297
= 0.0442m3/s
Result:
The discharge of the Nakkhu khola obtained from float method is given below.
Q=0.0442 m3/s
Comments:
The results obtained from different groups are different which is due to the reason that practical was not done accurately. If more accurate results are required, small increments in depths are recorded. Also if a floating rod or a specified object was used in floatation, it could give more accurate results. In the field, we floated small papers, plastics, etc which may also be the reason that the results given by different groups didn’t match.
We believe that such educational tour will be a lot of help for us in understanding the actual situation while undertaking any professional tasks in the future and we hope that IOE will continue such field tours.
Wednesday, June 29, 2011
Sanskriti lyrics By Mantra
SANSKRITI
Mantra
Birrrseko chhainau hami
Sanskriti aajhai pani
Nasa nasama purkha ko ragat
Bagda chha aajhai pani
(Sirma topi nahola hamro
Daura surwaal na hola)2* times
Tara chhati vari, maya chha aafnai jati pratiiii
(Deurali pakha viralo, kasari birsula
Yei mato ma janmeko, yesaima milaula)2* times
Naulo chha saili hamro
Naulo chha hamro yo vesh
Birseko chhainau tara
Pahad jharna khola ko desh
(Damphu ra madal nahola hamro
Sarangi nahola)2* times
Tara mutu vari maya chha yeha kai sangit pratiiii
(Maruni selo juwari, prerana hamrai ho
Je vaneni lok vaka, sarai nai ramro ho)2* times
(Sirma topi nahola hamro
Daura surwaal na hola)2* times
Tara chhati vari, maya chha aafnai jati pratiiii
(Deurali pakha viralo, kasari birsula
Yei mato ma janmeko, yesaima milaula)2* times
Maruni selo juwari, prerana hamrai ho
Je vaneni lok vaka, sarai nai ramro ho
Deurali pakha viralo, kasari birsula
Yei mato ma janmeko, yesaima milaula
Maruni selo juwari, prerana hamrai ho
Je vaneni lok vaka, sarai nai ramro ho
...
Mantra
Birrrseko chhainau hami
Sanskriti aajhai pani
Nasa nasama purkha ko ragat
Bagda chha aajhai pani
(Sirma topi nahola hamro
Daura surwaal na hola)2* times
Tara chhati vari, maya chha aafnai jati pratiiii
(Deurali pakha viralo, kasari birsula
Yei mato ma janmeko, yesaima milaula)2* times
Naulo chha saili hamro
Naulo chha hamro yo vesh
Birseko chhainau tara
Pahad jharna khola ko desh
(Damphu ra madal nahola hamro
Sarangi nahola)2* times
Tara mutu vari maya chha yeha kai sangit pratiiii
(Maruni selo juwari, prerana hamrai ho
Je vaneni lok vaka, sarai nai ramro ho)2* times
(Sirma topi nahola hamro
Daura surwaal na hola)2* times
Tara chhati vari, maya chha aafnai jati pratiiii
(Deurali pakha viralo, kasari birsula
Yei mato ma janmeko, yesaima milaula)2* times
Maruni selo juwari, prerana hamrai ho
Je vaneni lok vaka, sarai nai ramro ho
Deurali pakha viralo, kasari birsula
Yei mato ma janmeko, yesaima milaula
Maruni selo juwari, prerana hamrai ho
Je vaneni lok vaka, sarai nai ramro ho
...
Himali Nepali lyrics By Mantra
himali nepali
MANTRA
Gauthali chirbir gardaina, vane thyo hain gauthali
Koyeli kuhu vandaina, vane thyo haina koyeli
Garva nai bata aauchha, sabai vesh ra vasali
Yo vesh ra vasa nabirsau hamiii
Himali Nepali
Kasaile po vanla timilai, katai tyo haina timro desh
Vandinu unalai jaha ma, hunechhu tehi ho mero desh
Sagarmatha sero ra, phero himali pradesh
Yesaima bityo due pusta hamroooo
Yehi ho mero desh
Vasa ra sanskriti, sab ko janam ko
Sab ko janam ko adhikar
Kasaima yo guun,nahola vane
Tesaila chha mero dhikkar
Bachna ra hasna, paenna vane
Paaenna vane k ko swadhintaaaaaaaa
Bachna lai gaas navaye,vaigo aama chahinchha
Marma ko kura kholna, garva koooooo
Garva ko vasa ta chahinchha
Khola ra nala, pahad ra jharna
Yehi nai ho mero deshaaa
Chaubandi choli,Dhaka ra topi
Yehii nai o hamro vesha
Bachna ra hasna, paenna vane
Paaenna vane k ko swadhintaaaaaaaa
Bachna lai gaas navaye,vaigo aama chahinchha
Marma ko kura kholna, garva koooooo
Garva ko vasa ta chahinchha
Kasaile po vanla timilai, katai tyo haina timro desh
Vandinu unalai jaha ma, hunechhu tehi ho mero desh
Garva nai bata aauchha, sabai vesh ra vasali
Yo vesh ra vasa nabirsau hamiii
Himali Nepali
MANTRA
Gauthali chirbir gardaina, vane thyo hain gauthali
Koyeli kuhu vandaina, vane thyo haina koyeli
Garva nai bata aauchha, sabai vesh ra vasali
Yo vesh ra vasa nabirsau hamiii
Himali Nepali
Kasaile po vanla timilai, katai tyo haina timro desh
Vandinu unalai jaha ma, hunechhu tehi ho mero desh
Sagarmatha sero ra, phero himali pradesh
Yesaima bityo due pusta hamroooo
Yehi ho mero desh
Vasa ra sanskriti, sab ko janam ko
Sab ko janam ko adhikar
Kasaima yo guun,nahola vane
Tesaila chha mero dhikkar
Bachna ra hasna, paenna vane
Paaenna vane k ko swadhintaaaaaaaa
Bachna lai gaas navaye,vaigo aama chahinchha
Marma ko kura kholna, garva koooooo
Garva ko vasa ta chahinchha
Khola ra nala, pahad ra jharna
Yehi nai ho mero deshaaa
Chaubandi choli,Dhaka ra topi
Yehii nai o hamro vesha
Bachna ra hasna, paenna vane
Paaenna vane k ko swadhintaaaaaaaa
Bachna lai gaas navaye,vaigo aama chahinchha
Marma ko kura kholna, garva koooooo
Garva ko vasa ta chahinchha
Kasaile po vanla timilai, katai tyo haina timro desh
Vandinu unalai jaha ma, hunechhu tehi ho mero desh
Garva nai bata aauchha, sabai vesh ra vasali
Yo vesh ra vasa nabirsau hamiii
Himali Nepali
sadhai sadhai lyrics by mantra
Sadhai sadhai aayi rahancha, timro yaada haru
Yo man... eklai gungunaucha, atit ka ti dhun haru
Kati tadpe, parkhi rahe
(Farki timi aayenou, bedanama geeta kore)2
Sunideu yo geeta mero, amar rahosh yo prita hamro
Herda herdai paari chitij laai, aanshu khaschha thaha napai
Sakne vaye farkai lyauthe ma
Meri maya, timro haata samai
Kati tadpe, parkhi rahe
(Farki timi aayenou, bedanama sangit rache)2
Sunideu sageeta mero, amar rahosh, yo prita hamrooo
(Juni-juni timi sangai jiune, sapana mero timilai nai paaune)2* times
Tara kaha pugthyo ra, soche jati sabai
Sadhai... sadhai aahi rahancha, timmmro yaada haruuu
(Juni-juni timi sangai jiune, sapana mero timilaia nai paaune)2* times
Tara kaha pugthyo ra, soche jati sabai,
(Sadhai... sadhai aahi rahancha, timro yaada haruuuuu
Yo man... eklai gungunaucha, atiiitka ti dhun haru)2* times
Atiiiit ka ti dhun haruuuuu
Yo man... eklai gungunaucha, atit ka ti dhun haru
Kati tadpe, parkhi rahe
(Farki timi aayenou, bedanama geeta kore)2
Sunideu yo geeta mero, amar rahosh yo prita hamro
Herda herdai paari chitij laai, aanshu khaschha thaha napai
Sakne vaye farkai lyauthe ma
Meri maya, timro haata samai
Kati tadpe, parkhi rahe
(Farki timi aayenou, bedanama sangit rache)2
Sunideu sageeta mero, amar rahosh, yo prita hamrooo
(Juni-juni timi sangai jiune, sapana mero timilai nai paaune)2* times
Tara kaha pugthyo ra, soche jati sabai
Sadhai... sadhai aahi rahancha, timmmro yaada haruuu
(Juni-juni timi sangai jiune, sapana mero timilaia nai paaune)2* times
Tara kaha pugthyo ra, soche jati sabai,
(Sadhai... sadhai aahi rahancha, timro yaada haruuuuu
Yo man... eklai gungunaucha, atiiitka ti dhun haru)2* times
Atiiiit ka ti dhun haruuuuu
Ekantama by Mantra lyrics
Ekanta ma kina kina timrai nai yaad aaucha
samjhana ma ajhai pani aakha yo kina rasincha
thaha cha malie timi aaudinau
timi kasai ki bhai sakechau
tara kina kina feri samjhan chu
nadukhe ko mutu lie kina dukhau chu
eklai hinda kahile kahin timi saath ma paauchu
hinda hindai bolda boldai
ekali pauda jhaskanchu
thaha cha malie yo bhram ho
feri bhetine asha nai chaina
kati cheto bitechan milan ka ti paal haru
samjhana matra rahyo sapana sabai ojhel paryo
samjhana matra rahyo sapana sabai ojhel paryo
Ekanta ma kina kina timrai nai yaad aaucha
samjhana ma ajhai pani aakha yo kina rasincha
thaha cha malie timi aaudinau
timi kasai ki bhai sakechau
tara kina kina feri samjhan chu
nadukhe ko mutu lie kina dukhau chu
nadukhe ko mutu lie kina dukhau chu
samjhana ma ajhai pani aakha yo kina rasincha
thaha cha malie timi aaudinau
timi kasai ki bhai sakechau
tara kina kina feri samjhan chu
nadukhe ko mutu lie kina dukhau chu
eklai hinda kahile kahin timi saath ma paauchu
hinda hindai bolda boldai
ekali pauda jhaskanchu
thaha cha malie yo bhram ho
feri bhetine asha nai chaina
kati cheto bitechan milan ka ti paal haru
samjhana matra rahyo sapana sabai ojhel paryo
samjhana matra rahyo sapana sabai ojhel paryo
Ekanta ma kina kina timrai nai yaad aaucha
samjhana ma ajhai pani aakha yo kina rasincha
thaha cha malie timi aaudinau
timi kasai ki bhai sakechau
tara kina kina feri samjhan chu
nadukhe ko mutu lie kina dukhau chu
nadukhe ko mutu lie kina dukhau chu
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