0 views 2018-08-15 18:45:20
In this summer, a spate of heat waves have hit various countries and regions around the globe, arousing a string of natural disasters and calamities. California is now still under the biggest wildfire in its history, and an unprecedented drought has wreaked havoc on the east of Australia, while on July 23, a catastrophic fire disaster in a coastal area east of Athens, capital of Greece, has caused even more significant loss of life and property.
According to the latest news from Reuters, the wildfire, rated as the deadliest in Europe in the past century, has destroyed hundreds of hectares of forests, flattened villages and made people homeless. Many tourist resorts nearby Athens were heavily damaged, left the life of local residents very difficult. Lately, Greece’s fire brigade raised the official number of fatalities from the wildfire that raged through July 24 to 91 and reported that 25 people are still missing, with hundreds injured and thousands evacuated.
At the dawn of July 24, 2018, areas around Athens are still in ferocious blaze. In the footage, the flames from the forest fires have engulfed trees on the side of the road. Thick dark smoke obstructs the view for road users, as some escape from the inferno.
Fires are not uncommon in Greece’s forests. Affected by the Mediterranean climate, it is usually hot and dry in Greece in summer. Due to the basin topography of Athens situated in a valley, atmosphere temperature inversion phenomena often occurred here. Added by the lush forest vegetation covering almost half its territory, Greece has been severely afflicted and suffered regularly enormous fire prevention pressure every summer.
A firefighting helicopter flies over a wildfire raging in the town of Rafina, near Athens, Greece, July 23, 2018. Despite the government troops, navy frigate, fire brigade, coastal guards have all been mobilized with a helping hand from Spain and Cyprus to tackle the “extremely difficult” situation, the multi-point staggering fires have made everything a drop in the bucket. [Image/Reuters]
Since June, temperature in some areas of Greece has reached 40 degrees Celsius and multiple forest fires caused by dryness and thunders were alarmed. As reported, on July 23, an intense wildfire raided Rafina, a famous sightseeing harbor east of Athens. Whipped by strong gusts of ashore wind which was at the speed up to 124km/h and constantly shifted its directions, the roaring flames sprawls rapidly and swallowed through the pine forest-covered tourist village of Mati, left perhaps 20 minutes for the tourist concentration and local residents to save their lives. Major traffic trunk was cut off in the blaze and thick smoke while evacuation routes also narrowed or even blocked by the commonly seen illegal and unplanned constructed buildings in towns, which led to the catastrophe.
On the afternoon of July 23, three wildfire behaviors were reported in the west, east and northeast of Attika. Aided by strong winds, they spread swiftly and infringed on the nearby towns and villages, among which the seaside tourist resorts Rafina harbor and Mati Village suffered severe casualties. The village of Mati at the center of the disaster was razed to the ground after the fire.
The Kineta Township in the west of the Attika peninsula is also one of the most hit, where more than 800 buildings were subjected to blaze including 300 completely burnt, making the originally unprosperous local residents more difficult economically and some of them homeless. Janis is a truck driver who has his house built in the woods less than 100 meters from the beach. “Now it is gone, my wife, three kids and I lodge at other’s…” [Image/CCTV.com]
However, Greece is not alone. Soon after terrestrial plants appeared on the earth, devastating forest fires began and have kept breaking out throughout human’s history. According to the UN Food and Agricultural Organization’s statistics, there are nearly 220,000 forest fires took place each year all over the world, destroying 6.46 million hm2 of forests, which accounts for 0.13% of the worlds’ total forest areas. Whereas, figures show that the overall global forest coverage is currently 3.5 billion hm2, taking 26. 6% out of the land area, which is progressively decreasing at a rate of 1.04m hm2 each year. Meanwhile, environment deterioration, “greenhouse effect” and El Nino have also added to the situation and caused more frequent fires and loses.
How to tackle the high occurrence of forest fires and protect the annually decreasing forest resources and the safety of people’s life and property is a question for the mankind to resolve. Satellite remote sensing (RS) technology provides an optimized solution and has played a vital role in this regard.
It is generally difficult to detect the flame in a timely manner, hence serious damages and losses when it runs out of control. Therefore, fire prevention and monitoring is the first and most crucial step of tackling forest fires. Satellite RS monitoring works as a “clairvoyant” in detecting and identifying fire points. As the most advanced technical means of the highest spatial level in modern forest fire prevention and control, satellite RS technology makes up for the shortages of the traditional methods such as watchtowers and manual field surveys. By extracting, analyzing and comparing the land surface temperatures, humidity, infrared bands and other data, satellite RS could make early, accurate detecting and positioning of fire points. In addition to the advantages and characteristics of macroscopic observatory, wide coverage, high temporal resolution and time efficiency, it can also carry out all-weather, all-time and dead-zone free real time monitoring of forest fires.
Meanwhile, satellite RS technology applied in forest fire risk investigation and evaluation can also provide data for forest fire prevention and make the work more targeted and efficient. Fire risk indicators are categorized in five aspects: fire history, terrain, meteorological environment, vegetation and human factors. Besides, vegetation drying rate，equivalent thickness of water layers，land surface temperature，gross weight of the inflammable，vegetation continuity are also important factors to be considered by satellite RS monitoring.
According to the data of the Chinese meteorological satellite FY-3D developed by China’s National Satellite Meteorological Centre at 19:40, July 23, 2018, a major fire point appeared in Athens, Greece, with a sphere of influence 60 square kilometers and an estimated burning area of 32.4 hectares. Another two minor fire points can also be found in the north.[Image/Euronews.com]
During a forest fire, satellite RS technology is also applicable to the continuous and dynamic follow-up monitoring of the fire development, reporting the location, coverage, spreading direction, burning vegetation species, meteorology information of the fire behaviors, assisting the prediction of fire development tendency and the relief decisions; to evaluate the aftermath damage and loses, satellite RS imagery can provide data of the burned area of the fire. The burnt area is a fundamental factor for post-fire damage evaluation, referring to the total area that the blaze has raged, regardless of its intensity. It is an indicator of the disaster’s influence upon the vegetation and eco-environment. After a forest fire, the spectral traits of the ground truth will be distinctly altered. The burnt ones will be darker and deeper in color, contributing to an apparently decreased spectral reflectivity at the visible spectral band. By contrasting the pre and post-fire vegetation coverage, the solution establishes a reckoning mode and calculates meticulously the affected area； Satellite can also facilitate the recovery of forests by extracting and distinguishing the obtained images via varied reflection spectrums from different trees species, such as the evergreens, aquatic plants, ground flora, deciduous forest and shrub, offering basis for forestry resources investigation and protection. Multi-spectral RS data is applied to acquire the status quo, spatial distribution, coverage, dynamic changes and overall tendency of the forest resources, based on the establishment and demonstration of a 3D model of the forest. Forestry satellites are enabled to accurately estimate forest vegetation parameters such as chlorophyll content, leaf area index and biomass to foster forest resources management and a healthy and sustainable development of forestry.
ChangGuang Satellite Technology is a world’s leading commercial satellite producer, operator and remote sensing information service provider. We provide customized services to our global users leveraging a state-of-the-art remote sensing image processing, visual analytics, identifying and tracking, information extraction technologies, professional software and hardware, and superior R&D systems.
An aerial view of the headquarters of the ChangGuang Satellite Technology Co., Ltd. in Changchun City, Jilin Province, China. [Image/ChangGuang Satellite Technology]
Based on independent technologies of satellite and optical payload, ChangGuang Satellite Technology is now capable of producing 30 satellites annually. We always regard “Space-Sky-Earth integration” as our mission by which to give the world our excellent RS date products & services.
At present, the company has 5 senior professional titles, 15 deputy senior titles, 6 doctoral tutors, 7 master tutors, and recruits nearly 30 graduate students in the field each year. It has already established a professional technical team to foster the overall rapid development of the company.
On January 9, 2017, ChangGuang Satellite Technology successfully launched the first forestry satellite in China——Jilin-1 Forestry Constellation in the Jiuquan Satellite Launch Centre in China’s northwest Gansu Province. The especially designed satellite project for forestry application, focusing on the core needs of forestry administration and development, is a constellation of five stars. Its mission is to provide more affluent data services of a higher resolution, broader coverage, and ultra-short response time for forestry applications such as resources survey, fire monitoring, vegetation species investigation, wild animal protection, desertification treatment, wetlands monitoring, pest and disease prevention, etc.
ChangGuang Satellite Technology and its Jilin-1 Forestry Constellation has accumulated rich experiences while helping its customers to settle their various demands in forest fire prevention and monitoring, post-disaster evaluation and resources investigation and so on. For example, it has served the Jilin City in China’s northeast Jilin Province by assessing the city’s forest fire risk grade. The city has since then achieved a good mark of no fire disasters for a consecutive 33 years. It has also carried out data extraction of the burned area around the China-Russia borders, covering an area of 4,573.69 square kilometers.
Thematic Map of Forest Fire Danger Evaluation in Jilin City. Red represents hyper danger while green means no risk. [Image/ChangGuang Satellite Technology]
Burnt area distribution at China-Russia borders on April 29, 2017. The blue area stands for the burnt areas. [Image/ChangGuang Satellite Technology]
Jilin-1 Forestry Constellation provides images of spatial resolution less than 5m and forestry remote sensing data services in aspects of forest resources investigation, disaster monitoring, eco-value assessment and other fields.
The five-star networking adopts a sun-synchronous orbit. Orbital plane and equal-phase distribution is applied in the forestry satellite. It can make the revisiting interval time as short as 10 minutes and revisit key areas more than 30 times a day, ensuring the time efficiency.
The minimum interval between two adjacent satellites in networking takes 30 minutes or less to image the same object.
Each star of the Jilin-1 Forestry Constellation has the capability of large side-sway imaging, which can meet the real-time monitoring requests of natural disasters such as floods and fires.
19 visible near-infrared spectral bands, including 1 panchromatic band and 18 multi-spectral bands are configured in the forestry satellite; 4 short wave infrared spectral bands, 1 medium wave infrared spectral band and 1 long wave infrared spectral band, of a total of 25 spectral bands.
Elon Musk’s SpaceX is making rocket launching cheaper and cheaper while Skybox Imaging making satellites smaller and cheaper. There is reason to believe that with the development of technology, more and more satellites will be sent to the space. In the near future, we will be able to more frequently observe the ground truths and more frequently and accurately monitoring forest fires with satellites which will be playing an even greater role in protecting global forest resources and the living environment of the mankind.