Zhenguo Niu

Chinese Academy of Sciences | CAS · Key laboratory of Remote Sensing Science

In this paper, we report the first wetland mapping of the entire China using Landsat enhanced thematic mapper plus (ETM+) data. These data were obtained from the Global Land Cover Facility at the University of Maryland spanning from 1999 to 2002. A total of 597 scenes of Landsat images were georeferenced and mosaiced. Manual image interpretation of...

Two wetland maps for the entire China have been produced based on Landsat data acquired around 1990 and 2000. Wetlands in China have been divided into 3 broad categories with 15 sub-categories except rice fields. In 1990, the total wetland area in China was 355208 km2 whereas in 2000 it dropped to 304849 km2 with a net loss of 50360 km2. During an...

This paper presents a design and development of feature-based spatial-temporal data model with integrated spatial and temporal elements and whole spatial-temporal intension (FBSDTM) for dynamic monitoring of landuse. Firstly, fundamental theoretical framework of the feature-based spatial-temporal data model and data structure is developed based on...

This paper introduced the basic theory of hyper-graph and the development status of spatio-temporal model on the basis of the results of former people. Then through comparing various spatio-temporal data model and various spatio-temporal reasoning model, combining the technology of object-oriented and the realistic want of production, eventually co...

Monitoring of tobacco planted acreage is a very important step for tobacco's management and monitoring. The paper presents a monitoring method by data fusion of multiple remote sensing sources. It extracts tobacco areas according to the NDVI value and classifies the fusion image with texture information, then classifies the SAR data to acquire toba...

Although soil moisture is a key factor of hydrologic and climate applications, global continuous high resolution soil moisture datasets are still limited. Here we use physics-informed machine learning to generate a global, long-term, spatially continuous high resolution dataset of surface soil moisture, using International Soil Moisture Network (IS...

The 2030 Agenda for Sustainable Development provides an ambitious vision for global sustainable development in three dimensions: economic, social and environmental. It has, however, run into major challenges posed by such problems as the lack of data, unbalanced progress, and trade-offs between the Sustainable Development Goals (SDGs). At the same...

The Qinghai–Tibet Plateau (QTP), also known as the Third Pole of the Earth, is sensitive to climate change, and it has become a hotspot area for research. As a typical natural ecosystem on the QTP, alpine wetlands are particularly sensitive to climate change. The identification of different types of alpine wetland and analysis of changes in their d...

Wetland vegetation dynamics are of vital importance for comprehending changes in ecosystem structure and function. In the context of global climate change, it is still unclear the change in trends occurring to wetland vegetation in China. Using Global Inventory Modeling and Mapping Studies (GIMMS) Normalized Diference Vegetation Index product (NDVI...

Accurate wetland mapping is essential for their protection and management; however, it is difficult to accurately identify seasonal wetlands because of irregular rainfall and the potential lack of water inundation. In this study, we propose a novel method to generate reliable seasonal wetland maps with a spatial resolution of 20 m using a seasonal-...

Humans have been transforming natural surface water bodies into various types of artificial water cover to meet the growing demand for food, energy, and flood protection in recent decades. These changes have exerted cumulative impacts on the water cycle, environment, and ecology. Although the geographical distribution of and changes in water cover...

Rapid urban expansion and structural changes are taking place in China’s capital city, Beijing, but without an update of urban land features in a timely manner our understanding of the new urban heterogeneity is restricted, as land-background data is indispensable for bio-geophysical and bio-geochemical processes. In this plain region, the investig...

Wetland vegetation dynamics are of vital importance for comprehending changes in ecosystem structure. Under the background of global climate change, it is still unclear the change trends of wetland vegetation in China, and whether there are differences between the response of wetland vegetation and non-wetland vegetation to climate change. Based on...

The ecological vulnerability of global protected areas (PAs) is linked to the 2030 United Nations Sustainable Development Goals. We developed a novel degree of ecological vulnerability (DEV) index based on Big Earth Data to assess the ecological vulnerability of PAs. This is a transparent, repeatable, large-scale and rapid assessment method. We app...

As one of the most important steps in classification and mapping research, sample acquisition and updating cost a lot of time and energy of researchers. The high temporal and spatial dynamic characteristics of wetland makes the reliable wetland sample selection more challenging. It is especially important for time series wetland classification to a...

As one of the most important natural ecosystems on the earth's surface, the wetland is a natural geographical complex with multiple features and functions. Developing a wetland sample set at the national level is a major challenge. The function of the existing sample set is seriously limited due to the change of wetland types and lack of seasonal i...

Accurate assessment of global carbon sequestration is the key step to accurately assess future CO2 concentrations and predict climate change. At present，the spatial and temporal uncertainties of global terrestrial and oceanic carbon sinks are very large. Although the model simulation method is widely used in global carbon source/ sink research，many...

Water surface temperature is a direct indication of climate change. However, it is not clear how have China’s inland waters responded to climate change in the past using a consistent method on a national scale. In this study, we used Moderate Resolution Imaging Spectroradiometer (MODIS) data from 2000 to 2015 to study the temporal and spatial varia...

Inland surface water is highly dynamic, seasonally and inter-annually, limiting the representativity of the water coverage information that is usually obtained at any single date. The long-term dynamic water extent products with high spatial and temporal resolution are particularly important to analyze the surface water change but unavailable up to...

Surface water is the most important resource and environmental factor in maintaining human survival and ecosystem stability; therefore, timely accurate information on dynamic surface water is urgently needed. However, the existing water datasets fall short of the current needs of the various organizations and disciplines due to the limitations of o...

The alpine wetlands in QTP (Qinghai-Tibetan Plateau) have been profoundly impacted along with global climate changes. We employ satellite datasets and climate data to explore the relationships between alpine wetlands and climate changes based on remote sensing data. Results show that: 1) the wetland NDVI (Normalized Difference Vegetation Index) and...

This paper classifies wetlands in Jilin Province by using random forest algorithm, constructs a comprehensive evaluation system of landscape index and "pressure-state-response" model, and evaluates the ecological security of 18 wetland nature reserves and wetland parks inJilin Province from 2015 to 2017. The results showed that: (1) Among the 18 na...

Gathering accurate information on wetland distribution and changes is of key importance for wetland management. However, wetland mapping using single-date imagery is challenging due to high seasonal and intra-annual hydrodynamic variations, especially for seasonal wetlands. Although time series of satellite images are effective for improving the ac...

Wetlands have important functions and values in flood control and disaster mitigation, water resource regulation, mitigation of environmental pollution, protection of biodiversity, and maintenance of regional ecological environment. As one of the wetland systems in the northern plain of China, the Baiyangdian basin wetlands play a key role in safeg...

Wetlands have important functions and values in flood control and disaster mitigation, water resource regulation, mitigation of environmental pollution, protection of biodiversity, and maintenance of regional ecological environment.As one of the wetland systems in the northern plain of China, the Baiyangdianbasin wetlands play a key role in safegua...

Baiyangdian is the largest freshwater lake in the North China Plain. Understanding the spatial and temporal characteristics of Baiyangdian landscape and its relationship with the environment is of great guiding significance for restoring and improving the overall function of the Baiyangdian ecosystem and safely maintaining the ecological environmen...

Accurate spatial information is critical to the assessment and protection of wetlands in the context of human intervention and global climate change. However, it is challenging to map and monitor wetland vegetation classes with satisfactory results because of their highly seasonal dynamics, spatial heterogeneity, and spectral similarity. This paper...

Lake Dongping is the second largest freshwater lake in Shandong Province. It is also an important junction on the east route of south to north water transfer project and on the route of the west to east water transfer. However, Potamogeton crispus L. community's expansion has caused a series of ecological issues, including the waterway blocking and...

Intertidal zones, which are located in the transitional area of sea and land, are importantto biodiversity protection, social and economic development, and global environmental changes. Inthis study, the dataset that was generated using the integrated remote sensing and GIS methodbased on 156 Landsat Thematic Mapper/Operational Land Imager images c...

Intertidal zones are located in the transitional area of sea and land and are important to biodiversity protection, social and economic development, and global environmental changes. However, due to the irregular dynamics of the tides and the regular local time of satellite transit, it is challenging to monitor the extent of intertidal zones using...

Timely updating of wetland map is vital to wetland research and management. However, the highly hydro-dynamic characteristics and great spatial heterogeneity of wetlands pose challenges in updating large-scale wetland thematic maps in a timely manner. General mapping methods, such as supervised or object-oriented classification, are time consuming...

The alpine wetlands on the Tibetan Plateau (TP) are ecosystems vulnerable to global climate change. It has been recognized that future climate change may have a significant impact on methane (CH4) emissions from the plateau, while less attention has been paid to predicting temporal and spatial variations in CH4 emissions from TP natural wetlands. I...

Wetlands are vital for human survival. Considering there is no common wetland definition which is accepted by all domains or sectors, the Ramsar wetland definition is recommended for large-scale wetland mapping. Three kinds of methods for developing wetland dataset at large spatial scale—wetland mapping by remote sensing, compilation of historical...

Coastal wetlands as a unique ecosystems with high productivity and abundant biology diversity,has many important resource values,ecological values,economic values and scientific research values.Due to the multi-temporal,multi-platform,macroscopic,objective,informative, real-time,highly effective,comparable and so on,so the remote sensing technology...

Satellite-based wetland mapping faces challenges due to the high spatial heterogeneity and dynamic characteristics of seasonal wetlands. Although normalized difference vegetation index (NDVI) time series (NTS) shows great potential in land cover mapping and crop classification, the effectiveness of various NTS with different spatial and temporal re...

Accurate wetland delineation is the basis of wetland definition and mapping, and is of great importance for wetland management and research. The Zoigê Plateau on the Qinghai-Tibet Plateau was used as a research site for research on alpine wetland delineation. Several studies have analyzed the spatiotemporal pattern and dynamics of these alpine wetl...

Accurate wetland datasets are indispensable for generating polices on wetland conservation and appropriate land uses, global climate change studies, and biodiversity conservation. Although increasing numbers of global wetland-related datasets have been established, the extensive disagreements among these datasets are prominent. In particular, estim...

Wetlands are among the most bio-diverse and highest productivity ecosystems on earth, making their monitoring a high priority to conservation, protection and management interests. Although visual interpretation of satellite images is generally precise for monitoring wetlands, recent works have emphasized computerized classification methods because...

Intertidal zone is one of the most important coastal wetland types, which contains immeasurable value in biodiversity protection and global environmental changes. Remote-sensing technology has become an important tool for coastal wetland monitoring. However, there are still challenges to map intertidal zones due to the discrepancy between imagery a...

Globally, wetland loss and degradation have become serious environmental and ecological issues. Wetland monitoring of Ramsar sites in China is important for developing reasonable strategies to protect wetlands. Satellite image time series may be used for the long-term monitoring of wetland ecosystems. The present study used moderate-resolution imag...

Sustainable use of groundwater is critical to China's present and future food security. Natural groundwater resources of Huang-Huai-Hai plains (HHH), the region that produces 60-80% of China's wheat (Triticum aestivum) and 35-40% of its maize (Zea mays), are being jeopardized by excessive water withdrawal. While previous studies have assessed the g...

A technically transparent and freely available reference sample set for validation of global land cover mapping was recently established to assess the accuracies of land cover maps with multiple resolutions. This sample set can be used to estimate areas because of its equal-area hexagon-based sampling design. The capabilities of these sample set-ba...

Both anthropogenic activities and climate change can affect the biogeochemical processes of natural wetland methanogenesis. Quantifying possible impacts of changing climate and wetland area on wetland methane (CH4) emissions in China is important for improving our knowledge on CH4 budgets locally and globally. However, their respective and combined...

The popular method of wetland mapping, which is usually based on single-date satellite imagery, cannot meet the requirements of wetlands monitoring because of the highly dynamic features of wetlands. Using multi-temporal or time series satellite imagery is a good choice to monitor wetlands at large scale, and time series MODIS products with highly...

Sustainable use of groundwater is critical to China’s present and future food security. Natural groundwater resources of Huang[294TD$DIF]–Huai–Hai plains (HHH), the region [295TD$DIF]that produces 60–80% of China’s wheat (Triticum aestivum) and [296TD$DIF]35–40% of its maize (Zea mays), are being jeopardized by excessive water withdrawal. While pre...

Natural wetlands are among the most important sources of atmospheric methane and thus important for better understanding the long-term temporal variations in the atmospheric methane concentration. During the last 60 years, wetlands have experienced extensive conversion and impacts from climate warming which might result in complicated temporal and...

Knowing the spatial distribution of potential wetlands is vital for improving wetland mapping accuracy, understanding the spatial evolution of wetlands, and making policies for wetland conservation and restoration. Topographic characteristics are key factors for wetland distribution. We first separated natural sinks from false sinks in DEM data by...

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A database of global wetland validation samples (GWVS) is the foundation for wetland mapping on a global scale. In this work, a database of GWVS was created based on 25 “wetland-related” keyword searches of a total of 3,506 full-text documents downloaded from the Web of Science. Eight hundred and three samples from a total of 68 countries and 141 p...

Wetland, as a unique ecological system with highest productive forces on earth, is one of the most important environmental resources, which are named 'kidney of the earth'. Wetland mapping plays an important role on the scientific exploitation and conservation of wetland resources. It is convenient for a big range of wetlands extraction based on MO...

"Higher Resolution Global Land Cover Mapping" program requires global data from two base years (2000, 2010) with 30 m spatial resolution multispectral images for global land cover mapping. These data should undergo radiometric and geometric precision correction. The data mainly comprise Landsat TM/ETM+ images supplemented by HJ-1A/B CCD. In total,...

Wetlands are highly productive natural ecosystems, providing valuable goods and services. There is growing interest in transferring ecosystem service value from the existing wetlands studied to other wetlands ecosystems at a large geographic scale. The benefit transfer method uses the known values from wetlands to predict the value of other wetland...

Water-level changes from 56 of the 100 largest lakes in China were derived from ICESat/GLAS data during the period of 2003 to 2009. An automated method for determining the trend of water-level change had been proposed in this study. Lake water footprints were first identified from the ICESat/GLAS GLA14 data product. Water level change was then dete...

Wetland is an important ecosystem with the most abundant bio-diversity and the highest productivity on the earth. It has been paid wide attention in the world in recent years. Although visual interpretation of satellite images is generally more precise for identifying wetlands, most recent works has emphasized computerized classification methods be...

We have produced the first 30 m resolution global land-cover maps using Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) data. We have classified over 6600 scenes of Landsat TM data after 2006, and over 2300 scenes of Landsat TM and ETM+ data before 2006, all selected from the green season. These images cover most of the world'...

Four wetland maps for all China have been produced, based on Landsat and CBERS-02B remote sensing data between 1978 and 2008 (1978, 1990, 2000 and 2008). These maps were mainly developed by manual interpretation and validated by substantial field investigation in 2009. Based on these maps, we analyzed the 2008 wetland distribution in China and disc...

Although wetlands are well known as one of the most important ecosystems in the world, there are still few global wetland mapping efforts at present. To evaluate the wetland-related types of data accurately for both the Global Land Cover 2000 (GLC2000) data set and MODIS land cover data set (MOD12Q1), we used the China wetland map of 2000, which wa...