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On April 26, 2013, NASA’s Earth Observatory published a set of radar and satellite photos showing tropical forests and wetlands in the beautiful and mysterious Amazon basin of South America. With the release of such a set of photos, what is the purpose of NASA? The answer lies in its intention to evoke the importance of the wetland, the cradle of human life, and to call for action to protect these fading final pure land of human beings.
On March 17, 2013, NASA’s Landsat 7 satellite captured forest wetlands near the Napo River in Ecuador and Peru. The Landsat satellite project is a group of Earth observation satellites that the USGS and NASA have collaborated with. In the photo, yellow, orange, and blue indicate vegetation that may have been submerged by floods below the canopy of the forest. Green areas are relatively healthy forest vegetation, and their rough texture can be used to determine whether it is a complete forest vegetation or a forest or wetland that has been harvested. Black indicates the open water of the Napo River and its tributaries. These photos can help researchers map wetlands in the Amazon basin. [Image Credit: NASA]
Located in the south of the mysterious Amazon, Pantanal, the largest wetland in the world, glitters as a jewel in the vast South America. [Image Credit: NASA]
On Earth, the planet where humans survive, there exists a patch and another of magical areas, lying at the linkages of water and land. They are a source of life and a world to discover. Nourishing a diverse variety of animals, plants and microbes, it enjoys the good reputation of “a huge gene pool of species”. It contains rich fresh waters and deposits other precious natural resources. Versatility and high value as they are of, they are also known as the “kidney of the earth”, the “source of fresh water”, and “regulators” of climate change. As an ancient Chinese poem depicting the beauty of wetlands goes, “Tens of thousands of miles are the reeds and shoals, never compared is an autumn moon in eyes of a brook.”Now let’s follow satellite imagery and read the story of the earth.
At the south of the mysterious Amazon basin and the junction of Brazil, Bolivia and Paraguay lies the world’s largest wetland, the Pantanal swamp with a total area of 242,000 square kilometers. Situated in the huge Paraguayan basin and encircled in highlands, many winding rivers gather here, creating the world’s richest aquatic plants. It is considered to be the most densely populated ecosystem of plants and animals worldwide.
From the mountains to the sea, wetlands are at work for us. Wetlands, forests——the lungs of the earth and oceans——the heart of the earth are called the “three major” ecosystems of the world, and play an important role in maintaining ecological security, food security, and freshwater security.
Wetlands is irreplaceable in preserving biodiversity, rare species resources and ecological balance. The ecosystem is an organic integrity of flora and fauna, microbes and their environment. According to statistics, 40% of the world’s species live in freshwater wetlands covering only 6% of the Earth’s surface. They are dubbed the paradise of wild birds, the kingdom of animals, the ideal home for their reproduction and habitat and the midway stop for their migration and wintering. Complex and diverse plant communities also provide abundant food sources and good conditions for nesting and avoiding enemies for wild animals, especially the rare and endangered.
Pantanal is home to more than 3,500 species of plants and 2,000 of animals, and is named by the World Wildlife Fund as one of the world’s most vibrant habitats. Jaguar, giant anteater, giant capybara, caiman, golden dragonfly, hyacinth macaw are the protagonists of the dazzling “animal show” here. It is the best place to admire the world’s largest feline—— jaguar and the home of hyacinth macaw. The beautiful and friendly blue-violet macaw is endangered by the greed of poachers and the black market price of up to 10,000 dollars, leaving only some 3,000 living in the wild.
Flamingos and alligators constitute a unique landscape in the southern Florida’s Everglades, considered one of the three most important wetlands in the world. Owning the richest flora and fauna in North America, life grows in this deep watery and misty wilderness.
Wetlands are also a noteworthy guardian of the environment. These natural “sponges” conserve water, regulate runoff, store flood and prevent drought; they mitigate soil erosion, storm surges and disaster risks. They are also natural “filters” of environmental pollution. The powerful capacity of absorbing harmful components and metal ions in the sewage or industrial wastewater enables them to purify water, replenish the groundwater or to be used as a direct water source. Besides, its luxuriant flora absorbs harmful gases, dust and various pathogens in the air, regulate atmospheric components and thereby purifies the air; absorbs a large amount of carbon dioxide, releases oxygen and thereby reduces the greenhouse effect and regulates climate change. Moreover, the large amount of water stored in them can also be sent back to the atmosphere through plant transpiration and water evaporation, increasing air humidity and regulating precipitation. Therefore, its reputation of the “Kidney of the Earth” is well deserved.
An aerial view of grazing cattle at the Pantanal wetlands in Mato Grosso state, Brazil. The marching wild herds and the brightly lit Nerog River reflects the lush vegetation and exudes a mysterious primitive atmosphere. The Pantanal Marsh is decreasing at a rate of 2.3% per year. In recent years, human activities have posed enormous threats to it. Illegal hunting, deforestation and land reclamation have reduced the area of wetlands and endangered cherished species.
In addition, Wetlands, having a strong material production capacity, work as humans’ natural granary, supplying food (aquatic products, poultry products, grains), energy (hydropower, peat, fuel wood), raw materials (reeds, wood, medicinal plants) and tourist sites and sustaining the sustainable development of mankind.
The Mekong delta, the world’s third largest wetlands, is surrounded by water and covered by a dense river network. Villages are arrived at by boat. Bustling floating markets, fruit gardens, rice fields, sugar cane fields and quaint little villages attract visitors from all over the world. The 475 000 cubic km of water that Mekong discharges each year makes it ideal for rice cultivation and green-pincered crawfish breeding. It feeds the country and is often referred to as Vietnam’s “rice bowl” and a land of rice and fish in Southeast Asia.
However, the most valuable and productive ecosystems economically and ecologically have been severely damaged in recent centuries. According to the British “Daily Mail” report on July 3, satellite photos taken 40 years apart show that human activities have caused terrible destruction to earth resources. Since 1900, at least 64% of the world’s wetlands have disappeared. Scientists predict that by 2050, 66% of the world’s population will live in cities and towns. With the rapid increase of population and soil destruction, environmental damage, water and air pollution, continuous and large-scale reclamation and unreasonable exploitation of wetland resources in the wake, a significant reduction of wetlands will be caused. Wetland protection is in urgent.
The Everglades consist of a shallow sheet of fresh water that rolls slowly over the lowlands and through billions of blades of saw grass. As water moves through the Everglades, it causes the saw grass to ripple like green waves; hence the nickname “River of Grass.” Several hundred years ago, the Florida Everglades was a major part of a 5,184,000 acre watershed that covered almost a third of the entire state of Florida. The flow and human interruption of this river is clearly visible from space. [Image Credit: NASA]
To protect wetlands, the complex and highly sensitive land-water linked ecosystems, the premise is to identify, distinguish and analyze the impact of human activities and climate change, and to obtain quantitative and accurate access to the status and trends of wetlands from time, space and different research scales. Satellite remote sensing (RS) technology provides a new solution for this purpose.
Covering a wide area of hundreds of thousands of square meters, wetlands require an aerial detection from a broader perspective. Satellite RS imagery provides high-frequency macro-environmental images that can accurately locate targets globally or over large areas and also broadens our vision with an enlarged spectral bands sphere.
The great Okavango Delta, located in southern Africa, north of the Republic of Botswana, is the largest inland delta on Earth with an area of approximately 15,000 square kilometers. Running from the Angola Pentium, the Okavango River waters the largest oasis in Africa in the Kalahari Desert. The Delta in the Kalahari Desert is illuminated in the Sun’s reflection point in this panorama taken from the International Space Station (ISS) on June 6, 2014. Using this sunglint technique, astronauts can capture the fine detail of water bodies. [Photo Credit: NASA]
The difficulty of surveying wetland resources also determines the necessity of using satellite remote sensing images for investigation and monitoring. Given people can neither walk nor boat on a piece of wetland and their hard-reaching location, the traditional investigation and monitoring methods are infeasible and low efficient. For example, tropical forests and wetlands are the most attractive and important areas of research for geoscientists and ecologists, but they are also a difficult area of research. “In the Amazon, many forests have seasonal or semi-permanent floods and are remotely located, with no roads or navigable rivers,” said Bruce Chapman, a scientist at the NASA Jet Propulsion Laboratory. This means that if satellites are used, researchers can obtain ground data in any season, whether it is rainy or dry.
Traditional field sampling methods have a small coverage and are time consuming and destructive to the ecosystems. Remote sensing is the act of collecting data without directly contacting its source. For example, scientists can determine the landscape of the ocean floor without walking on it. That is the reason the technologies are widely used in countries around the world in the area.
Located in the south of Vietnam and the mouth of the Mekong River, the Mekong Delta is the richest and most densely populated place in Vietnam with an area of about 44,000 square kilometers and a population of 20 million people. This Envisat image features Vietnam’s Mekong Delta, where the Mekong, the world’s 12th longest river, fans out into tributaries and empties into the South China Sea in Southeast Asia. Ho Chi Minh, Vietnam’s largest city and chief port, is visible as white in the upper right corner. [Image Credit: ESA]
Land subsidence is threatening the fertile land of the Mekong Delta. Ground and satellite instruments have detected that the average settlement rate of this delta is 1 to 4.7 cm per year. Shrimp farmers in the delta are pumping huge amounts of groundwater into ponds, causing a drop in groundwater levels, accumulation of overlying sediments, and subsidence of the ground. This trend will put the delta under flood and other threats. [Image Credit: ESA]
Moreover, incorrect or inconsistent information largely exists in the data or statistics collected through the traditional surveys, while the RS technique owns qualities of objectiveness, correction and accuracy, economic effectiveness in wetland resources investigation. It also has superiorities in quantification, multi-temporal and large amount of data. The continuous improvement of image processing technology has also greatly enhanced the ability of satellites to quantitatively extract and analyze wetland information. Thanks to the popularity of high-resolution images, the RS technique has advanced from traditional large-scale areas towards microscopic researches.
The analysis and identification of RS information is mainly based on the reflection spectrum and wavelength variation of the ground object of the wetland features, that is, the spectral characteristics of the ground object from the visible lights to the infrared and microwave spectral bands. Photography is another method of RS. Satellites can take “pictures” of the amount of infrared and visible light the earth gives off or reflects. Scientists analyze these images to estimate the pattern and distribution of water or vegetation covering the wetland in different periods. These RS images are processed later to more readable and measurable RS imagery maps, which surpass ordinary maps in objectiveness, authenticity, updating and information containment.
Satellite RS dynamic monitoring also plays a vital role in wetlands protection and recovery administration. A long-term administration of recovered wetlands is essential, requiring dynamic monitoring of major wetlands elements including soil, waters, flora and fauna, etc.
RS images make it possible for us to objectively and accurately understand wetlands’ distribution in different periods; Maps of different periods foster understanding of their changes, degradation scales and the status quo of the damaged wetland ecosystem, based on which protection and recovery strategies are made.
Since biodiversity is one of the most important functions of wetland ecosystems, research on wetland vegetation biomass has also been the focus of wetland conservation. Practice has shown that remote sensing technology can effectively estimate the distribution, growth status and changes of wetland biological resources. The vegetation spectral model can be used to invert the biological parameters of wetland vegetation. It is also possible to use the band values of the two typical bands of the near-infrared and visible-red bands and the vegetation index to map the wetland biomass. Hyper-spectral resolution images are of great value here.
Environmental adaptability evaluation of wild animals is never to be ignored in wetland protection. The RS technique provides a more advanced approach for environment livability assessment with advantages of massive and quick data acquisition and low cost to elevate administration level of wild animals.
Flocks of red gazelle galloping through the marshes, a most primitive call of the wild from the Okavango Delta, which presents the world with a unique and intact desert wetlands landscape. The well-preserved lush wonderland supports a highly diverse number of plant and animals species such as wild elephants, rhinos, hippos, lions and zebras, always back for food after the rainy season and floods.
The noble and graceful red-crowned crane is regarded as a symbol of good fortune and longevity in China. Zhalong Natural Reserve is located in Qiqihar City, Heilongjiang Province, with a total area of 210,000 hectares, ranking first in Asia and fourth in the world. It grows the largest amount of reeds globally. The Wuyuer River, a tributary of the Nenjiang River overflowed here forming the large swamp. Dotted with rivers and lakes, it is dubbed the “Heaven of waterfowl and birds” and “hometown of red-crowned crane”.
The Changguang Satellite Technology Co., Ltd. has accumulated abundant practical experiences in wetlands protection, wetlands ecosystems restoration, vegetation biomass monitoring, environmental adaptability evaluation of wild animals, etc. One of the successful cases is the analysis of the evolution of the wetlands ecosystem in the west of Jilin Province. The demonstration area is divided into 5 basic ecosystems including the farmland, wetland, saline-alkali, residential and water ones. RS imagery technology is applied to monitor the time and spatial alternations of these ecosystems.
The Jilin-1 Constellation of Changguang Satellite Technology also has had successful practice in the environmental adaptability evaluation of wild animals. It utilizes its high-resolution multi-spectral imagery as well as RS, DEM and other basic geographic data in combination of analytic hierarchy process and GIS comprehensive evaluation to analyze the impacts of vegetation status, geographical environment and human interference factors on habitat adaptability of Siberian tigers.
The image shows a contrast between the wetlands in 1994 and 2015. The Green parts are farmlands developed from the wetland. [Image/Changguang Satellite Technology]
Habitat Adaptability Spatial Distribution Map for Siberian Tigers in Hunchun City, Jilin Province, China. Red represents the inadaptable part for the animal. [Image/Changguang Satellite Technology]
The Jilin-1 constellation developed by the Changguang Satellite Technology provides all sorts of RS images of high quality and precision, which have superior advantages in environmental protection. It has 10 stably running satellites in orbit with reinforced capability of data collecting; up to 0.72m resolution images provide detailed ground truth; breaking the externally environmental limitation and providing more qualified and efficient environmental monitoring services; and the ability and agility to collect data twice per day leads to the maximized efficiency.
In the field of wetland protection, the remote sensing imagery technology has been widely used in countries and regions on the globe with a bright prospect. Changguang Satellite Technology has always believed that it can do more. Quoting the themes of World Wetlands Day in 2008 and 2016 as saying——“healthy wetland, healthy people” and “wetlands for our future, sustainable livelihoods”, wetlands are the breeding ground for human beings and many other equally important animals and plants. It’s time for us to act to safeguard this last pure land on earth and leave a blessed one for ourselves.