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Identification of cropping pattern and estimation of water

requirement using remote sensing

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INTRODUCTION The water requirement has been increasing more and more especially in agriculture. The agricultural sector makes use of 75% of the water withdrawn from river, lakes and aquifers. In recent years irrigated land has developed rapidly. Water increasingly often becomes a limiting factor for food production especially in dry climates. In dry climates water sources are very limited since the amount of rain-fall is very low. As the total size of the hot dry areas in the world is about 45-50 million square kilometres which means one third of the total land area of the world. In dry climate the availability of water for irrigation of crops is limited, which restricts the possibility for cultivation of crops. For that reason a lot of research has been done to develop methods to protect water and using less amount of fresh water as far as possible without effects on crops yield, and to increase water use efficiency in irrigation without any negative effects on crop yields. Thus irrigation scheduling is one of the best methods which can help us to realize these aims.

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LITERATURE REVIEW M. Anadranistakis et al.(1999) :Evapotranspiration was

calculated using temperature,humidity,wind speed,root depth,crop height etc using penman monteith method.the results showed a deviation of 8% form the experimental results

A.W. Abdelhadi et al.(1999) :Evapotranspiration was calculated using penman monteith,farbrother method the results for penman monteith method were more accurate than the farbrother method.the farbrother method gave higher values

J. G. Annandale et al. (2001) :Evapotranspiration was calculated using a short programme named CROPWAT written in delphi and based on penman monteith method.this was widely used by the food and agricultural organization.5 day averages were taken instead of daily averages resulting in more accurate predictions

K H V Durga rao et al. (2001) :using different image processing techniques crop type and their area coverage was calculated for a area in deheradun evapotranspiration was calculated using CROPWAT the current irrigation schedule was proved to be more than necessary thus a revision of the irrigation schedule was proposed

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1. Identify the types of crops and the area occupied by those crops using satellite or aerial images.

2. Estimate the water requirement for the different type of crops during their base period.(sowing to harvesting)

3. The product of the area occupied by the crops and the base period water requirement will give the total water requirement for that particular irrigation area.

OBJECTIVES

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Efficient use of available water resource & Sustainable watershed management

we can decide the water requirements for suggested cropping pattern by irrigation department)

It helps in the design of irrigation project.

what are its benefits?

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Crops have low reflectance in the visible region and have high reflectance in infrared region.

The crops in the image cannot be distinguished accurately with visible spectrum alone.

Hence multispectral images are obtained by using multispectral sensors mounted on satellites

By obtaining the LISS-IV IMAGE , preparing the NDVI Map for a particular region, we can identify the types of crop grown in the area.

1. Crop identificationhow its done?

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For example

True colour image:The different crops

cannot be seen distinctively

False colour or infrared image:

We can see the contrast between different crops

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But before that we need to know how those crops appear at different times of the year and their growing season

lastly all the information is processed using a software such as ERDAS and ARC-GIS to obtain the area under each crop

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Water is utilized in crops mainly for evapotranspiration Evapotranspiration (ET) is the sum of evaporation and plant transpiration

from the Earth's land and ocean surface to the atmosphere. Factors that affect evapotranspiration include the plant's growth stage or

level of maturity, percentage of soil cover, solar radiation, humidity, temperature, and wind.

2. CROP WATER REQUIREMENTWHAT IS IT?

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PENMAN MONTEITH METHOD FOR ESTIMATION OF REFERENCE CROP EVAPOTRANSPIRATION:

this is one of the most accurate methods for the estimation of evapotranspiration

Reference crop evapotranspiration is defined as the evapotranspiration from a hypothetical crop with an assumed height of 0.12m having a surface resistance of 70 s/m and an albedo of 0.23, closely resembling the evaporation of an extension surface of green grass of uniform height, actively growing and adequately watered.

The software CROPWAT 8.0 was used to simplify the calculations involved in the estimation of evapotranspiration

METHOD USED FOR ESTIMATION OF EVAPOTRANSPIRATION

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The equation for reference evapotranspiration is: given by:

where: ETo= Reference evapotranspiration [mm /day] Rn = Net radiation at the crop surface [MJ /m2/day] G = Soil heat flux density [MJ/ m2 /day] T = Mean daily air temperature at 2 m height [°C] u2 = Wind speed at 2 m height [m/s] es = Saturation vapour pressure [kPa] ea = Actual vapour pressure [kPa] ∆ = Slope vapour pressure curve [kPa /°C] γ = Psychrometric constant [kPa/ °C]

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The various parameters required for the equation are:

Latitude in degree and minutesAltitude in metersMaximum temperatureMinimum temperatureWind velocitySunshine hoursMean temperature

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DATA USED: The following data products are used for the present study:

Survey of India (SOI) Topomap on 1:50,000 scale (to prepare the base map to get information the command area)

Hydro meteorological Data (Estimation of reference crop evapotranspiration by penman monteith method )

Satellite images ( LISS 3 and LISS 4) (to identify the cropping pattern in the study area)

Cadastral map (to know the area details like Survey Number & Area under irrigation, from Revenue Department & Irrigation Department)

Crop data (as per the suggested cropping pattern from irrigation department)

Data products & Methodology

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STUDY AREA DETAILSGoogle image

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Study area location

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The study area is located south west of Davangere city in Davangere district

The study area is supplied by the right bank canal network from the Bhadra reserviour

The study area consists of the command area of the 10th distributary of the Harihara branch canal.

10th distributary having an area of 38.88sq.km(3888 hectares)

The study area lies between from 75.796 to 75.886 decimal degrees longitude and from 14.377 to 14.411 decimal degrees latitude

LAND COVER Major portion of the land is used for agriculture,

horticulture ,plantations of area groundnut, coconut ,water bodies, barren scrubs

The soil mainly consists of red soil followed by black soilTHE HARIHAR BRANCH CANAL

The 10th distributary of the harihar branch canal has a design discharge of 1.765cumecs

The 10th distributary takes off from the Harihar branch canal at 15.3 km

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METHOD OF DATA ACQUISITION Field Survey was carried out using a GPS device Borewells and wells were taken as reference points, a topomap

was developed using arc gis with the help of the GPS coordinates

PROCEDURE FOR CROPPING PATTERN ESTIMATION

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NDVI map was generated using the LISS-III & LISS IV map

Supervised classification was carried out on the NDVI map. The steps taken for supervised classification are as follows:

1. Defining training samples2. Generate signature file3. Perform most likelihood classification

Filters and corrections were applied to obtain the final classified image

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The following weather data was entered into the CROPWAT 8.0 software

PROCEDURE FOR ESTIMATION OF EVAPOTRANSPIRATION

Month Min TempMax Temp Humidity Wind Sun Rain°C °C % km/day hours mm

January 16.3 30.1 66 69 8.5 0February 18.2 32.8 65 77 8.4 0

March 20.8 35.5 57 34 8.8 21.2April 22.9 36.5 57 41 9 25.2May 23 35.2 61 65 7.6 115June 22.1 30.5 27 49 4 89.2July 21.5 28.1 75 75 1.9 153.6

August 21.5 28.3 73 79 3.8 99.2September 20.8 29.3 72 35 4.6 330.2

October 20.6 30 69 48 5.2 105.2November 18.3 29.3 67 172 9.8 26.2December 16.1 29 66 79 3.8 0

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The following are the crop data for some crops

Banana:

Maize:

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CROPWAT interface

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NDVI map generated using the LISS 3 map

RESULTS

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Classified map obtained by supervised classification

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After applying filtering and corrections the final classified map was obtained

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The areal information of the cropping pattern obtained was as follows:

land use area(sqm) area(hectares)sugarcane 1225811.546 122.5811546single rice 4889876.297 488.9876297

maize 737911.5978 73.79115978double rice 27445981.8 2744.59818

coconut 841015.4332 84.10154332built up area 1418468.603 141.8468603barren land 731838.9495 73.18389495

banana 2004747.776 200.4747776arecanut 1454758.992 145.4758992

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Reference evapotranspiration ET0 and effective rainfall obtained from CROPWAT for the year 2015

Month ETo Eff rainmm/day mm

January 3.5 0February 4.11 0

March 4.49 20.5April 5.03 24.2May 4.91 93.8June 3.75 76.5July 2.95 115.9

August 3.41 83.5September 3.32 158

October 3.33 87.5November 4.43 25.1December 2.73 0

Average 3.83 684.9

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The decadewise irrigation (mm/decade)for the various crops was obtained as follows:

Irrigation requirement=ET0×Kc - effective rainfall

sugarcane banana barley maize rice(rabi) rice(khariff) arecanut coconut total irrigation(mm/dec)Jan-01 39.2 30.4 9.9 9.9 36.4 0 33.84 37.92 197.56Jan-02 42.5 34.1 12.5 10.8 39.5 0 38.07 42.66 220.13Jan-03 49 40.7 27 18.3 45.9 0 43.3575 48.585 272.8425Feb-01 46.5 40 38.7 27.1 44.2 0 41.2425 46.215 283.9575Feb-02 48.5 42.3 45.1 37.9 46.8 0 43.3575 48.585 312.5425Feb-03 39.6 34.6 36.9 37.2 38.5 0 34.7975 39.005 260.6025Mar-01 44 39.5 42.4 43.5 44.5 0 40.3725 45.855 300.1275Mar-02 40.2 38.1 41.1 42.3 43.3 0 38.93 44.54 288.47Mar-03 44.9 45.2 49 50.3 51.5 0 46.2325 52.735 339.8675Apr-01 42.7 43.4 41.8 48.9 50.1 0 47.275 53.65 327.825Apr-02 43.2 43.7 30.1 40.4 50.3 0 49.99 56.62 314.31Apr-03 30.2 20.1 5.8 17 36.4 0 40.2325 46.735 196.4675May-01 13.4 0 0 0 0 0 25.5175 31.765 70.6825May-02 0.7 0 0 0 0 103.9 15.36 21.48 141.44May-03 1.5 0 0 0 0 161.3 19.7175 25.965 208.4825

Rabi season:

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Khariff seasonsugarcane banana barley maize rice(rabi) rice(khariff) arecanut coconut total irrigation(mm/dec)

Jun-01 0 0 0 0 0 19.4 16.6 21.7 57.7Jun-02 0 0 0 0 0 17.8 15.27 19.86 52.93Jun-03 0 0 0 0 0 9.7 7.855 12.19 29.745Jul-01 0 0 0 0 0 0 0 0 0Jul-02 0 0 0 0 0 0 0 0 0Jul-03 0 0 0 0 0 0 0 0.62 0.62

Aug-01 0 0 0 0 0 7.9 4.6825 8.635 21.2175Aug-02 11.1 0 0 0 0 14.9 12.0975 16.305 54.4025Aug-03 9.1 0 0 0 0 8.3 5.37 9.96 32.73Sep-01 0 0 0 0 0 0 0 0 0Sep-02 0 0 0 0 0 0 0 0 0Sep-03 0 0 0 0 0 0 0 0 0Oct-01 1.4 0 0 0 0 0 0 1.12 2.52Oct-02 9 0 0 0 0 0 3.9825 7.935 20.9175Oct-03 25.3 5.5 0 0 0 0 20.3 25.4 76.5Nov-01 36.9 16.9 0 0 0 0 31.3725 36.855 122.0275Nov-02 50.4 29.7 0 0 0 0 43.1025 49.095 172.2975Nov-03 44.5 28 0 0 0 0 38.9575 44.185 155.6425Dec-01 37.1 25.5 0 0 3.3 0 32.6825 36.635 135.2175Dec-02 29 20.9 0 0 114.8 0 25.38 28.44 218.52Dec-03 36.9 27.5 0 0 181.6 0 31.725 35.55 313.275

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The decadewise irrigation volume requirement obtained was as follows:

Irrigation volume = Irrigation requirement × area under crop

crop arecanut rice khariff rice rabi maize coconut sugarcane banana total discharge(cum/sec)Jan-01 49229.04 0 177991.4972 7305.32474 31891.31 48051.8126 60944.3324 375413.3167 0.434506154Jan-02 55382.68 0 193150.1137 7969.44517 35877.72 52096.9907 68361.8992 412838.8423 0.477822734Jan-03 63074.71 0 224445.322 13503.7821 40860.73 60064.76575 81593.2345 483542.5525 0.559655732Feb-01 59997.9 0 216132.5323 19997.4041 38867.53 57000.23689 80189.9111 472185.5107 0.546511008Feb-02 63074.71 0 228846.2107 27966.8493 40860.73 59451.85998 84800.8309 505001.199 0.584492129Feb-03 50621.98 0 188260.2374 27450.3111 32803.81 48542.13722 69364.2731 417042.7421 0.482688359Mar-01 58732.26 0 217599.4952 32099.1542 38564.76 53935.70802 79187.5372 480118.915 0.555693189Mar-02 56633.77 0 211731.6437 31213.6603 37458.83 49277.62415 76380.8903 462696.4136 0.535528256Mar-03 67257.15 0 251828.6293 37116.953 44350.95 55038.93841 90614.5995 546207.2145 0.632184276Apr-01 68773.73 0 244982.8025 36083.8768 45120.48 52342.15301 87006.0535 534309.0955 0.618413305Apr-02 72723.4 0 245960.7777 29811.6282 47618.29 52955.05878 87607.4778 536676.6388 0.621153517Apr-03 58528.59 0 177991.4972 12544.497 39304.86 37019.50869 40295.4303 365684.381 0.423245811May-01 37121.81 0 0 0 26714.86 16425.87472 0 80262.54273 0.092896461May-02 22345.1 3359695.66 0 0 18065.01 858.0680821 0 3400963.833 3.936300733May-03 28684.21 5215773.91 0 0 21836.97 1838.717319 0 5268133.804 6.097377087

irrigation discharge required(cum/decade)

Rabi season

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Khariff season

crop arecanut rice khariff rice rabi maize coconut sugarcane banana total discharge(cum/sec)Jun-01 24148.9994 627315.647 0 0 18250.03 0 0 669714.6812 0.775132733Jun-02 22214.16993 575578.274 0 0 16702.57 0 0 614495.0104 0.711221077Jun-03 11427.13195 313657.823 0 0 10251.98 0 0 335336.9335 0.388121451Jul-01 0 0 0 0 0 0 0 0 0Jul-02 0 0 0 0 0 0 0 0 0Jul-03 0 0 0 0 521.4296 0 0 521.4295686 0.000603506

Aug-01 6811.909018 255453.279 0 0 7262.168 0 0 269527.3562 0.311952959Aug-02 17598.947 481804.286 0 0 13712.76 13606.5082 0 526722.4973 0.60963252Aug-03 7812.05583 268387.622 0 0 8376.514 11154.8851 0 295731.0768 0.342281339Sep-01 0 0 0 0 0 0 0 0 0Sep-02 0 0 0 0 0 0 0 0 0Sep-03 0 0 0 0 0 0 0 0 0Oct-01 0 0 0 0 941.9373 1716.13616 0 2658.07345 0.003076474Oct-02 5793.577718 0 0 0 6673.457 11032.3039 0 23499.33909 0.027198309Oct-03 29531.6077 0 0 0 21361.79 31013.0321 11026.11 92932.54459 0.107560815Nov-01 45639.42673 0 0 0 30995.62 45232.446 33880.24 155747.734 0.180263581Nov-02 62703.7498 0 0 0 41289.65 61780.9019 59541.01 225315.3134 0.260781613Nov-03 56673.77374 0 0 0 37160.27 54548.6138 56132.94 204515.5922 0.236707861Dec-01 47545.16102 0 16136.59178 0 30810.6 45477.6084 51121.07 191091.0298 0.221170173Dec-02 36921.78342 0 561357.7989 0 23918.48 35548.5348 41899.23 699645.8246 0.80977526Dec-03 46152.22928 0 888001.5355 0 29898.1 45232.446 55130.56 1064414.873 1.231961659

irrigation discharge required(cum/decade)

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The violation in cropping pattern is observed as follows:Crop Notified area(hectares) Actual area(hectares) %violation

Rice 62.04 3233.5858 5112.098324

sugarcane 120.21 122.5811 1.972464853

plantations 1262.74 430.0521 65.94294154

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1. Irrigation scheduling is the key element to proper management of irrigation system by applying the correct amount of water at the right time to meet the requirement of water to the plants. 2. From classification we can find huge violation of cropping area and because of that shortage of supplied water in the tailrace. It’s clearly shows that there is proper water management is required in the study area. 3. Scheduling efficiency was much lower for all treatments during the rainy summer season compared to the other drier seasons indicating inaccuracy in determining site specific rainfall. 4. Most crops will recover overnight from temporary wilting if less than 50 percent of the plant available water has been depleted. Therefore, the allowable depletion volume generally recommended is maximum 50 percent. However, the recommended volume may range from 40 percent or less in sandy soils to more than 60 percent in clayey soils. 5. The allowable depletion is also dependent on the type of crop, its stage of development, and its sensitivity to drought stress 6. When the irrigation scheduling is designed according to historical climate data or estimated by computer program, it is important to look at the crop in the field for color change or measuring soil water status to make sure that the estimation is right, because this kind of scheduling does not take into account weather extremes which are different

CONCLUSION

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The same procedure could be carried out for other locations facing irrigation problems

Suitable irrigation scheduling can be developed to meet the deficit irrigation requirements

FUTURE WORK

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