Recent analysis of satellite imagery focusing on rice cultivation in the Ansok Tideland, located in Ongchon County, South Pyongan Province, has revealed a concerning trend. Many rice stalks appear stunted and have failed to take root properly. This stunted growth may be attributed to hasty rice planting despite insufficient desalinization of the soil following seawater flooding.
The Ansok Tideland gained attention in August 2023 when Typhoon Khanun caused significant damage, resulting in a dike collapse that submerged an area more than twice the size of Seoul’s Yeouido district. In response, North Korean authorities repaired approximately 100 meters of the collapsed dike, drained the flooded area, attempted to desalinate the soil, and reestablished rice fields. Despite these efforts, satellite imagery analysis indicates that rice seedling growth remains abnormal, likely due to inadequate salt removal from the soil.
The satellite data is from the European Space Agency’s (ESA) Sentinel-2 satellite (10-meter resolution). North Korea may have rushed to harvest rice in the less flooded Ansok Tideland area, where the fall rice harvest is expected to be poor. The fiery wrath of Kim Jong Un, who visited the region during the flooding caused by the typhoon, may have spurred officials to rush to restore the rice fields and transplant rice. Ultimately, this year’s fall harvest will prove how successful those efforts were.
Ansok Tideland’s rice paddies are not doing well
Sentinel-2 imagery captured on June 3 reveals that rice planting in the Ansok Tideland paddy fields was largely complete, with only a few dry fields remaining. The imagery shows the characteristic greenish-blue hue of healthy paddy fields in several areas, indicating normal growth of rice seedlings over the preceding days.
However, a subsequent image taken on June 13 presents a concerning development. In the center-left portion of the image, an abnormal blue coloration is evident, as if there has been localized flooding within the tideland. This coloration indicates that young rice seedlings are likely failing to establish root systems and are instead floating on the water’s surface. This unusual phenomenon may be attributed to residual salinity in the soil, a consequence of inadequate desalinization following the seawater inundation.
The 10-meter resolution Sentinel-2 satellite image is unable to distinguish the details of the floating rice seedlings. This is inferred from the fact that the color of the rice fields is not a healthy bright green, but rather a flooded, blue color, which suggests that the seedlings are floating and thus lost. In a few places, the rice seedlings have faded to a grayish color. As they have shifted from a healthy green color to gray, the seedlings appear to have failed to grow properly.
To find out more about the condition of the rice planting in the Ansok Tideland, I conducted a normalized difference vegetation index (NDVI) analysis. The NDVI is an index that indicates the vitality of surface vegetation and is widely used in satellite image analysis. For the analysis, the vegetation index was calculated from the images of June 3 and 13, and then a change analysis was performed to check how well the rice was growing in the tideland’s rice fields. The ERDAS IMAGINE program was used to process and analyze satellite images, and NDVI Differencing was used in the analytical process. A thresholding value of 1.0 standard deviation was applied to distinguish between good, fair, and poor rice growth conditions.
Results of the NDVI analysis
Based on the NDVI analysis, only 280 hectares or 47% of the 603 hectares of restored areas in the Ansok Tideland were found to have normal rice growth. On the other hand, 27% or 166 hectares were found to have poor rice growth, while the remaining 26% or 157 hectares were found to be in good condition. In 27% of the area, more than a quarter of the Ansok Tideland, rice plants were found to be unable to grow normally, which may be due to excessive rice harvesting without proper removal of saline seawater. This indicates that the harvest in the Ansok Tideland will fall far short of targets during the fall harvest.
In addition, the analysis found that a 423-hectare reclamation area is planned next to the Ansok Tideland, where dikes have been built to retain water. This area may also be drained of seawater and reclaimed for new rice fields. At the lower end of the Ansok Tideland, there is a 940-meter extension of the seawall, which may be used as part of North Korea’s “Seeking New Land” reclamation efforts that are aimed at addressing the country’s shortage of arable land.
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July 01, 2024 at 12:30PM
by DailyNK(North Korean Media)