Sampling Frame of Square Segment by Points for Rice Area ...

Mubekti

Center of Technology for Natural Resources Inventory The Agency for The Assessment and Application of Technology

BPPT Build-1. Fl. 12, Thamrin St., Jakarta, Indonesia e-mail: [email protected], Phone: +62 21-316 9412

Outline Background

Steps of Area Frame Implementation

Area Frame Construction

Field Survey

Data Communication and Data Analysis

Results Presentation

Conclusion

Further Development

Background

• The existing rice area estimate is based on reporting system and assimilated from sub-district to central level that subjects to bias results and take a long time

• There is a will of government (President Office for Development Control, MoA, and CBS) to improve the existing method of rice statistics in respect to accuracy and timeline

• We have experience on developing area frame sampling approach for rice area estimate

• Rapid development of remote sensing, GIS, and communication system encourage to develop ‘sampling frame of square segment by points’

• I believe that this method is an appropriate approach for Indonesian agricultural statistics

Area Frame Sampling Experience in Indonesia

1998-2002 :

• Segment size : 100 Ha • Survey method: Land cover delineation on segment area • Data delivery: postal services • Data analysis: GIS processing • Implementation time: 4 weeks

Complicated and takes time

2005-2007: • Segment size: 25 Ha • Survey method: Land cover delineation on segment area • Data delivery: postal services • Data analysis: GIS processing • Implementation time: 3 weeks

Still Complicated and takes time

2008-2012: • Segment size: 25 Ha • Survey method: land cover observation on sample point • Data delivery: SMS gateway • Data analysis: numerical calculation • Implementation time: 1 week

Simple and quick

Steps of Area Frame Implementation

Area Frame Construction • Stratification of AoI • Sampel size Definition • Sample segment extraction

Survey Preparation

• Survey equipments (field map, aerial photo/image, GPS, Survey Form)

• Surveyor (training)

Field survey

Observe and record growing stages of rice in each sampel point

Field data delivery

Data analysis and results presentation

7

Stratification of AoI (West Java and Banten Provinces)

Strata: S-1 (bright green): rice field S-2 (dark green): possible rice field (dry land arable) S-0 (white): non-agriculture land (forest, plantation)

Tool: •GIS software •digital landuse map

500 m x 500 m

10 km x 10 km

10 k

m x

10

km

Extraction of sample segments steps by ‘systematic random sampling’

1. Gridding AoI by 10 km x 10 km

2. Sub-gridding by 500 m x 500m

3. Random start extraction-1: 2,5 % (10 segments/grid)

4. Replicate the pattern of extracted sample segment to other grids

Definition of Dimension

•Segment size: (500x500) m2

•Sample size: 1 %

RESULT OF SAMPLE SEGMENT EXTRACTION

‘SYSTEMATIC RANDOM SAMPLING’

Next Step: Overlay between strata map and extracted sample segment

map

Overlay: Strata Vs Sample Segment

Next step:

• sample segments on S-0 are eleminated

• select 1 % sample segment ( 4 segments/grid) systematically (no. 1,2,3,4)

• 1 km distance threshold.

Distribution map of exctracted sample segments (1 %)

West Java and Banten Provinces

Cropping based on District administration

50

0 m

500 m

•54 extracted sample segments

•Each extracted segment is devided into small cells (100 m x 100 m size)

•The center of the cell as observation point

•In order to know sub-district and village location, the selected sample segments are plotted on tematic map

•Each segment is equiped by aerial photo or satellite image to make easier looking for segment and observation point

•Field survey time window is 2-month

S-0

S-1

S-2

Indramayu District

SEGMENT PLOT ON THE THEMATIC MAP

How to make segment ID on data base

• Each segment has bottom-left geographical coordinate

• Segment number

32: Province Code 17: District Code 741: Grid number 02 : sequence of randomozation

How to look for segment location in the field

•Identify sub-district and village •Identify an efficient road to go •Identify other phisical feature on the map

SEGMENT PLOT ON THE IMAGE

How to reach observation point

•Identify physical feature on the image (road, settlement, rice field, irrigation canal, dyke, etc)

•Define from where to start field survey

•Define observation point location

Note: Image guidance is easier to find location in the field compared GPS guidance

Field Survey Objective

To derive the existing rice growing stages on the observation point

Activities

Define observation point location

Observe and record rice growing stages on the survey form

Recapitulate the number of growing stages

Fill in SMS form based on the recapitulation result

Send the field data by HP

Visualization of rice growing stages

PL V1 V2

G P

B

LL

1-35 day 35 -55 day

55-105 day

Uncultivated rice filed

Rice field for other crops

Land preparation for rice Vegetative-1 Vegetative-2

Generative Harvest

Fill in the survey form

LL

LL

LL

PL

P

PL

PL

PL

PL

V1

V1

V1

V1

V1

V2

V1

V1

V1

V1

V2

V2

V2

V2

G

V1

AFS 01 321462106 04 00 00 04 00 00

Temporary Table

SMS Generator

Fixed Table

SMS field data

Setting SMS notification

SMS notification

SMS reading

Correct SMS

Estimator

Structure of SMS Communication System

jn

1i

ij

j

j pn

1p

j

j

n

i

jij

jj

p ppnn 1

22 )()1(

1

jjj pDA jpjj DAVar 2)(

m

j

jAA1

Estimator of extrapolation Sample to population

Pj : average proportion of rice in segment-i, strata-j

nj : sample size in strata-j

Dj: Total area of strata-j

Aj: Estimated rice area in strata-j

A: Total area of rice in the whole Distict

j: number of strata

i: Sample segment i-th

δ: variance

20

Indramayu District, total area: 207.675 Ha

Survey period: 03 September 2012 to 10 September 2012

Total Segment : 54 Recieved data: 52 data Area frame : 145.750,00 Ha

No Sub-district Segment PL V1 V2 G P LL B H No Sub-district Segment PL V1 V2 G P LL B H

1 Sindang 321470803 0 0 0 0 20 5 0 0 28 Gantar 321462003 0 0 0 0 0 6 19 0

2 Kandanghaur 321470603 0 0 0 0 21 4 0 0 29 Terisi 321466401 0 0 0 0 23 2 0 0

3 Kandanghaur 321466406 0 0 0 0 22 3 0 22 30 Gantar 321462106 0 0 0 0 0 5 20 0

4 Kandanghaur 321470504 0 0 23 0 0 2 0 0 31 Gantar 321462004 0 0 0 0 0 14 11 0

5 Losarang 321466503 0 0 0 0 23 2 0 11 32 Gantar 321457906 0 0 0 0 0 8 17 0

6 Losarang 321470601 0 0 0 0 0 25 0 0 33 Balongan 321466706 0 0 0 0 0 25 0 0

7 Bangodua 321462403 0 0 0 0 20 5 0 0 34 Widasari 321462406 0 0 0 0 25 0 0 0

8 Cantigi 321470704 0 0 0 0 0 21 4 0 35 Kroya 321466301 0 0 0 0 0 0 25 0

9 Bangodua 321462304 0 10 0 0 6 4 5 0 36 Kroya 321462206 0 0 0 0 0 3 22 0

10 Sliyeg 321466601 0 0 0 0 24 1 0 0 37 Kroya 321462103 0 0 0 0 0 5 20 0

11 Sliyeg 321466604 0 0 0 0 5 20 0 0 38 Kroya 321462104 0 0 0 0 0 0 25 0

12 Kertasemaya 321462503 0 0 0 0 13 12 0 0 39 Cikedung 321462306 0 0 0 0 0 5 20 0

13 Krangkeng 321462603 0 0 0 0 0 2 23 0 40 Lohbener 321466606 0 0 0 0 23 2 0 0

14 Krangkeng 321458406 0 0 0 0 0 25 0 0 41 Lelea 321466501 0 0 0 0 12 1 12 0

15 Anjatan 321470401 0 0 0 24 0 1 0 0 42 Lelea 321466504 0 0 0 0 6 2 17 0

16 Juntinyuat 321466704 0 0 0 0 20 0 5 0 43 Losarang 321466404 0 0 0 0 25 0 0 0

17 Juntinyuat 321466701 0 0 0 0 18 7 0 0 44 Losarang 321466403 0 0 0 0 0 25 0 0

18 Cikedung 321462201 0 0 0 0 0 5 20 0 45 Tukdana 321458206 0 0 0 0 12 13 0 0

19 Cikedung 321462204 0 0 0 0 0 8 17 0 46 Tukdana 321462401 0 0 0 0 25 0 0 0

20 Anjatan 321466206 0 0 0 20 0 5 0 0 47 Patrol 321470506 0 0 0 0 9 16 0 0

21 Anjatan 321470403 0 0 18 0 0 7 0 0 48 Patrol 321470404 0 2 22 0 0 1 0 0

22 Haurgeulis 321462006 0 0 0 0 0 0 25 0 49 Sukra 321474601 17 5 0 0 0 3 0 0

23 Haurgeulis 321466204 0 0 0 0 0 2 23 0 50 Sukagumiwang 321458203 0 0 0 0 21 4 0 0

24 Haurgeulis 321466203 0 0 0 0 0 8 17 0 51 Bongas 321470503 0 0 6 15 0 4 0 0

25 Haurgeulis 321466201 0 0 0 0 0 5 20 0 52 Bongas 321470501 0 0 5 14 0 6 0 0

26 Gabuswetan 321466303 0 0 0 0 23 2 0 0 TOTAL 17 17 74 73 412 340 367 33

27 Gabuswetan 321466304 0 0 0 0 16 9 0 0

Illustration of recieved field data

Total observed points: 1.300

Total frame area : 145.750,00 Ha

Rice growing stage Total obs.

point Proportion

(%) Area (Ha)

Land Preparation (PL) 17 1,3 1.895

Vegetative-1 (V1) 17 1,3 1.895

Vegetative-2 (V2) 74 5,7 8.308

Generative (G) 73 5,6 8.162

Harvest (P) 412 31,7 46.203

Other land cover (LL) 340 26,2 38.187 Uncultivated rice field (B) 367 28,2 41.102 Harvest in between 2-survey (H) 33 2,5 3.644

Harvest next 2-month (Prediction) 16.470

Harvest next 4-month (Prediction) 20.260

Calculating Rice Area

Results Presentation on http://neonet.bppt.go.id/padi

http://neonet.bppt.go.id/padi

http://neonet.bppt.go.id/padi

Conclusion

• Area frame of square segment by points is a simple approach to implement on rice statistics

• it is a scientifically sound approach based on statistical analysis and unbiased by subjectivity

• Saves time on frame contruction and survey works

• By using SMS system for data communication allow to get near real time results

• It is based on low technology and does not need high investment costs

• implementation costs are very low once it has become a routine activity

• With slight adaptations it can be applied to other crops

Success achieved and issues for further research

• Related institutions, i.e. MoA, CBS and UKP4 (Presidential Office for Develoment Monitoring), give a high attention to support the method for National level implementation

• The pilot project of the method is mainly dedicated for district level, so that is still need an adaptation for up-scale or down-scale level in respect to sampel size and segment size

• The method will be improved for not only rice statistics but also secondary food crops statistics

• The integration method between rice area estimate and yield estimate is a further research, where the existing sampling frame of yield estimation based on house hold frame would be area frame, instead.