[Yang Nak-gyu's Defense Club] North Korea, Another Surprise Discharge at Hwanggang Dam This Time (Comprehensive)

[Asia Economy Yang Nak-gyu, Military Specialist Reporter] As heavy rain is expected in North Korea, the frontline area has also been put on alert. This is because there is a high possibility that North Korea will conduct a sudden discharge from the Hwanggang Dam on the upper Imjin River or that North Korea’s wooden box landmines installed in the frontline area may be washed away.

On the 3rd, North Korea’s Korean Central Broadcasting reported that from tonight until the 5th, a "medium-level warning" will be issued for the central and southern regions, and a "caution warning" will be issued for parts of North Pyongan Province and Jagang Province. In particular, heavy rain of over 250mm is expected in South and North Hwanghae Provinces, Kaesong City, and inland Gangwon Province, with some areas forecasted to receive between 300 to 500mm.

In 2016, North Korea also conducted an unauthorized discharge from the Hwanggang Dam, causing damage worth hundreds of millions of won to fishing gear installed by fishermen in the lower Imjin River area. In October 2015, three days before the 70th anniversary of the founding of the Workers' Party of Korea, North Korea released water from the Hwanggang Dam, forcing anglers around the Imjin River to evacuate urgently. In 2009, six people died around the Imjin River due to unauthorized discharge from the Hwanggang Dam. If North Korea suddenly releases water at a rate of 500 cubic meters per second from the Hwanggang Dam, the discharged water will reach the South Korean Gunam Dam, located 50 km downstream, within 30 minutes.

North Korea operates a total of five dams in the Imjin River basin upstream of the Gunam Flood Control Dam (Gunam Dam) in Yeoncheon County, Gyeonggi Province. At 9.8 km upstream of the Hoengsan Water Level Station, there is the April 5 Dam No. 1 (each dam has a total storage capacity of 2,000 to 3,000 tons), and at 30.8 km upstream, there is April 5 Dam No. 2. Upstream of the Hwanggang Dam are April 5 Dam No. 3 and No. 5.

The distance between the Gunam Dam, which South Korea has operated since 2010 to prepare for floods caused by discharges from the Hwanggang Dam, and the North Korean Hwanggang Dam is 56.2 km. The first place in South Korea where changes in the Imjin River water level due to discharges from the Hwanggang Dam can be actually confirmed is the Pilsung Bridge Hoengsan Water Level Station. The Hoengsan Water Level Station is located 10.5 km north of the Gunam Dam.

There are three main ways to confirm whether the Hwanggang Dam is discharging water. The first is satellite images of the Hwanggang Dam; the second is visual confirmation when water overflows from April 5 Dam No. 1. The overflow status of April 5 Dam No. 1 can be immediately confirmed by the Gunam Dam and the military. The third is changes in the water level at the Hoengsan Water Level Station, which can also help estimate the discharge volume to some extent.

With heavy rain falling in North Korea, there is also a high possibility that wooden box landmines will be washed away. The "mokham landmine" is an anti-personnel landmine made of pine wood. In the frontline area, wooden box landmines washed away during the monsoon season have been found before. North Korean wooden box landmines are wooden boxes measuring 20 cm in width, 9 cm in length, and 4.5 cm in height, containing 200g of explosives and a detonator. If the box is opened or a certain amount of pressure is applied, it is designed to explode, with a lethal radius known to be within 2 meters.

The wooden box landmine is designed to explode when approximately 10 kg of weight is applied to the top, and even if one tries to forcibly open the box lid, it will explode due to the pressure. Inside the box are about 220g of TNT explosives and a detonator device including an MUV fuse, safety pin, ball, and spring. Recently, some mines made of plastic instead of wood have also been identified. Because they are made of pine wood, the more recently manufactured mines have a strong pine resin smell. Due to the wooden or plastic materials, these mines are dangerous as they are not detected by metal detectors commonly used for mine detection.

Civilian injuries caused by North Korean mines washed away by floods have also occurred frequently. In 2017, a wooden box landmine was found on Achado Island in Ganghwa County, Incheon. In July 2010, a resident named Han (50), who was illegally fishing in the Sami Stream, a tributary of the Imjin River inside the civilian access control line in Jangnam-myeon, Yeoncheon County, Gyeonggi Province, picked up two wooden box landmines and was carrying them out when one exploded, resulting in his death at the scene.