Spatial distribution of rice planting pattern using Sentinel-1A SAR in Pabuaran District, Subang Regency, Indonesia

Hana YAdi Wibowo, M.Si., PhD.Drs. Kustiyo, M.Si.

Introduction and Literature Review

Almost all Indonesians consume

rice as a staple food [8].

Approximately 50% of the national rice

production concentrated in Java Island, and

widely planted in the northern part of West

Java, especially Subang Regency [4].

Subang Regency is a strategic area for national rice

production centre. Pabuaran District is one of the districts

in Subang that have wide planting area, 9,328 hectares in

a year. However, the productivity of rice fields in

Pabuaran District tends to fluctuate every year [6].

The fluctuating and uncertain

productivity → will affect the

availability of national rice [7].

Remote sensing techniques offer

considerable benefits for detecting

rice growth in a short time and at low

cost [8] [14].

Source: grindgis.com

Monitoring rice plants using SAR

Sentinel-1A data has a large effect on the

backscatter value [13].

→ →

→ →

→

Method

Rice Planting Period Identification.

→Maximum Likelihood Classification: to group the data that have relatively

same backscatter and spectral values into several classes. Resulting in five

phases; land preparation phase, vegetative phase, reproductive phase,

generative phase, and the fallow phase

The maximum likelihood classification results then compared with the

ground truth data with statistical analysis using a confusion matrix.

Spatial Distribution of Rice Planting Pattern.

→Grouped by identifying changes in the rice planting period at each sample

points by considering at the trend of backscatter value, and information from

the interviews with the farmers during field surveys. Sample locations

(pixels) which similar temporal pattern and backscatter value then grouped

into the same class.

Data Collection.

→14 scenes Sentinel-1A imagery (October 2018 to November 2019) from Google Earth Engine

Data Processing.

→Sentinel-1A images are downloaded using GEE and have been processed in some stages automatically

using Sentinel-1 Toolbox from ESA: Thermal Noise Removal, Radiometric Calibration, and Terrain

Correction.

Rice Planting Period

The planting periods in Pabuaran District is divided into three periods,namely October 2018-January 2019, February 2019-May 2019, and June2019-September 2019. This split refers to the trend of backscatter valuesand harvesting data from Subang Regency Agriculture Office in 2018 until2019. Based on the data from the Subang Regency Agriculture Office, thehighest harvested area for rice fields in Pabuaran District are in January,April, and August

Results and Discussion

-30

-25

-20

-15

-10

-5

0

10 11 12 1 2 3 4 5 6 7 8 9 10 11-30

-25

-20

-15

-10

-5

0

10 11 12 1 2 3 4 5 6 7 8 9 10 11

-30-25-20-15-10-50

10 11 12 1 2 3 4 5 6 7 8 9 10 11

Colour Rice growth phase

Land preparation (0-34 days)

Vegetative (35-55 days),

Reproductive (56-90 days),

Generative (91-120 days)

Fallow (> 120 days)

SAR backscatter behaviour regarding rice planting period

Triple-cropped rice Double-cropped rice

Single-cropped rice

Results and Discussion

Distribution of Rice Planting Pattern

Based on the trend of the backscatter value at each sample points, there are six patterns of rice planting pattern in PabuaranDistrict, Subang Regency (Figure 5). The rice planting pattern is determined based on changes in the backscatter valuethroughout the year to determine when the paddy fields were planted with rice and left empty, which is also supported by theresults of interviews with farmers.

The use of SAR data in viewing the Sentinel-1A backscatter value can use for monitoring the phase of rice growth. By using

time series data, it can find that for 14 months, from October 2018 to November 2019, the paddy fields in Pabuaran District

have different rice planting period, those are single-cropped rice, double-cropped rice, and triple-cropped rice. The beginning

of the planting period is marked by the lowest backscatter value because the energy transmitted is reflected away from the

sensor because the surface of the rice fields is still smooth. Meanwhile, the backscatter value that continues to increase until it

reaches a maximum indicates that rice plants are in the vegetative to a reproductive phase whereas energy reflected in all

directions. The various planting periods can see from the trend of the backscatter value at the sample locations.

The rice planting pattern is determined based on changes in the backscatter value throughout the year to determine when the

paddy fields were planted with rice and left empty, which is also supported by the results of interviews with farmers. The rice

planting pattern in Pabuaran District, Subang Regency based on the backscatter value pattern is divide into six classes. Those

are (1) paddy-paddy-paddy, (2) paddy-paddy-fallow, (3) paddy-fallow-paddy, (4) fallow-paddy-paddy, (5) paddy-fallow-

fallow, and (6) fallow-paddy-fallow. Dominated of planting patterns on paddy-paddy-fallow that distributed around Pabuaran

District.

Conclusion

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