Xiyong Hou

Spatial-temporal Characteristics of Land Use Intensity of Coastal Zone in China During 2000-2010

Based on remote sensing and GIS techniques, land use maps in 2000, 2005 and 2010 in China’s coastal zone were produced, and structural raster data of land use were further generated to calculate land use intensity comprehensive index (LUICI) for analyzing land use spatial-temporal characteristics at 1 km scale. Results show that: 1) from the perspective of spatial patterns of landforms at a macro scale, there is a significant difference in land use intensity between the north and the south of China’s coastal zone. Hotspots of changes mainly concentrated in metropolitan areas, estuaries and coastal wetlands; 2) elevation is an important factor that controlling land use spatial patterns at local scale. Land use intensity is much higher within areas below the elevation of 400 m and it decreased significantly as the elevation increasing; 3) there is a significant land-ocean gradient for land use intensity, which is low in island and near-shore areas, but high in the regions that 4–30 km far away the coastline because of much intensive human activities; however, in recent decades land use intensity had been promoted significantly in low near-shore area due to extensive sea reclamations; 4) significant differences of land use intensity were also found among provincial administrative units. A rising trend of land use intensity was found in provincial-level administrative units from 2000 to 2010. To sum up, elevation, land-ocean gradient, socio-economic status and policy are all influencing factors to the spatial patterns and temporal variations of land use intensity in China’s coastal zone.

Characteristics of coastline changes in mainland China since the early 1940s

Based on multi-temporal topographic maps, remote sensing images and field surveys covering the entire coastal zone of mainland China, the coastlines of six periods since the early 1940s were extracted. Coastline changes over the last 70 years were then analyzed in terms of coastline structure, coastline fractals, coastline change rates, land-sea patterns, and bay areas. The results showed that mainland coastline structure changed dramatically, and due to the significant coastline artificialization mainly driven by sea reclamation and coastal engineering, the remaining natural coastline merely accounts for less than one third at present. Coastline fractal dimension represented an overall spatial pattern of “north < entirety < south”; however, the discrepancy between the north and south coast was apparently narrowed due to dramatic coastline artificialization of northern China which in turn altered the whole pattern. Patterns and processes of land-sea interchange along the mainland coast were complex and varied spatially and temporally, with over 68% advancing toward sea and 22% retreating toward land. The net growth of land area was nearly 14.2 ×103 km2 with an average growth rate of 202.82 km2 a−1; and coast retreat was characterized by area decrease of 93 bays with a magnitude of 10.1 ×103 km2 and an average shrinking rate up to 18.19% or an average shrinking speed up to 144.20 km2 a−1, among which the total area of Bohai shrunk by 7.06%, with an average annual loss amounting to 82 km2. The dramatic coastline changes along mainland China have brought about kinds of challenges to the coastal environment, therefore the integrated management, effective environment protection and sustainable utilization of coastlines is urgent.

Detecting Shoreline Changes in Typical Coastal Wetlands of Bohai Rim in North China

Coastal wetland shoreline change represents one of the most important land-ocean interaction processes in complex and dynamic coastal environment. This paper presents the detecting of shoreline changes in four typical coastal wetlands of ecological importance along Bohai rim based on multi-temporal shorelines extracted from obtained Normalized Difference Water Index (NDWI) images using automatic binarization algorithm. Results showed that although there were statistical uncertainties dominant trends of the shoreline changes could be detected and sections that had significant area changes could be identified from satellite images. The reasons for corresponding changes occurred in these wetlands were stated in terms of natural processes and anthropogenic activities. It is our anticipation that this work would help future studies to reveal the regional/national pattern of wetland changes and support wetland protection and management in China’s coast zone.

Coastal economic vulnerability to sea level rise of Bohai Rim in China

Through index-based method, the coastal economic vulnerability of Bohai Rim in China to the hypothetical local scenario of 1-m relative sea level rise by the end of twenty-first century was assessed (note that 1-m global sea level rise throughout the twenty-first century is highly improbable). Both physical and socioeconomic variables were considered, and the comparison between physical vulnerability and economic vulnerability was conducted to identify effects of socioeconomic variables on coastal susceptibility to sea level rise. The assessment was carried out at shoreline segments scale as well as at county-level scale, and the results were as follows: The combination of geomorphology and terrain plays the determinant role, since the gently sloped coasts with softer substances are always both physical and economic susceptible to the projected inundation scenario; potential displaced population and GDP loss have more influence on economic vulnerability than reclamation density in that the most intensively reclaimed areas are not always high vulnerable, while the areas that may suffer from the largest potential displaced population and GDP loss are always high vulnerable; the method employed in this study is sensitive in identifying the relative difference in economic vulnerability; moreover, it is capable of handling the issues caused by mutual offset effects between land-controlling impacts and marine-controlling impacts. The insights offered by this study could inform the coastal managers in optimizing allocation of limited resources and, consequentially, assist them to sequence policy, planning and management choices efficiently and effectively to adapt to the sea level rise.

Role of reservoir construction in regional land use change in Pengxi River basin upstream of the Three Gorges Reservoir in China

The impact of the Three Gorges Reservoir (TGR) construction on land use change has attracted worldwide concern. However, quantitative evidence is lacking for the drivers of land use change resulting from the TGR during and after construction. We used the Pengxi River basin, located upstream of the Three Gorges dam, to evaluate the effects of large-scale hydrological engineering on land use. Landsat remote sensing images from 1995, 2000, 2005 and 2010 covering the main construction period of the TGR were obtained. The largest changes were the conversion of land to water bodies and built-up areas, corresponding to reservoir impoundment and population resettlement during TGR construction. These changes were more intensive downstream of the TGR and closer to the river. Compared with 2000–2005, the expansion in water bodies during 2005–2010 moved from lower to higher elevations. The distribution of built-up land during the two periods was similar, mainly because the planned resettlement zones were fixed and spatially concentrated. Geographical and environmental factors, such as elevation, slope, location, soil type and precipitation, still controlled land use patterns. Land use pattern in 2020 under two scenarios was simulated using a multi-criteria evaluation cellular automata–Markov model. Scenario 2 was more realistic and helpful for management decisions. The scenarios highlighted the indirect influences of TGR construction on land use change after 2010. Indirect driving forces were mainly reflected through related policies or plans, especially from the perspective of water conservation in the newly built reservoir.

Spatial-temporal characters of evapotranspiration in the Yellow River Delta

Evapotranspiration (ET) is an important variable for water and energy balances on the earths surface. Surface Energy Balance Algorithm for Land (SEBAL) is an image-processing model that calculates ET over vast areas. In this study, time series of MODIS data in 2009 and meteorological data are used to estimate ET over the Yellow River Delta (YRD) by SEBAL, and then the spatial-temporal characters of ET are analyzed. It shows that, monthly average ET presents a unimodal distribution that the peak value locates in June, ET changes with the corresponding of climate and underlying surface coverage variations over time and season; there are great spatial diversities of ET, Water and beach have a relatively high level of ET which are mainly located in the northeast and northern of the study area. ET in Guangrao County tends to decrease from May to July, and then increase rapidly in August, finally decreases sharply in September and October.

Application of spatio-temporal data mining and knowledge discovery for detection of vegetation degradation

Increasing time-series remote sensing images provide the information about the evolution processes of ecosystems on multi-spatial scales. Vegetation plays an important role in sustaining the natural environment and supporting human being with goods and ecosystem services. Detection of vegetation degradation has become a hot spot of multi-disciplinary researches recently. In this paper, a case study of spatio-temporal data mining and knowledge discovery for detection of vegetation degradation has been conducted. The special issues focused on the quantitative determination of historical evolutionary trend and furthermore, the sustainability of different trends in the future. Taking the Circum-Bohai-Sea region as the case study area, the Unary Linear Regression Model (ULRM) has been established based on the time-series SPOT-VGT images from 1998 to 2008, and then the Hurst index has been calculated by R/S method on the spatial scales of cell (1km2) and the whole study area. It turned out that, the combined analysis between Slope of ULRM and Hurst index could effectively reveal the characteristics of vegetation changes, which included the degraded areas in the past as well as the risk level of degradation in the future. Overall, the areas of vegetation degradation in the future amount to 38.87 thousand square kilometers, which accounts for 7.55% of the whole study area. In addition, these degraded areas mainly distributed around the metropolitan regions, coastal zone, and so on. The findings will help us with more intelligent strategies of degradation prevention.

Ecological risk caused by land use change in the coastal zone: a case study in the Yellow River Delta High-Efficiency Ecological Economic Zone

Chinas coastal zone plays an important role in ecological services production and social-economic development; however, extensive and intensive land resource utilization and land use change have lead to high ecological risk in this area during last decade. Regional ecological risk assessment can provide fundamental knowledge and scientific basis for better understanding of the relationship between regional landscape ecosystem and human activities or climate changes, facilitating the optimization strategy of land use structure and improving the ecological risk prevention capability. In this paper, the Yellow River Delta High-Efficiency Ecological Economic Zone is selected as the study site, which is undergoing a new round of coastal zone exploitation and has endured substantial land use change in the past decade. Land use maps of 2000, 2005 and 2010 were generated based on Landsat images by visual interpretation method, and the ecological risk index was then calculated. The index was 0.3314, 0.3461 and 0.3176 in 2000, 2005 and 2010 respectively, which showed a positive transition of regional ecological risk in 2005.

Status quo of Water Science & Technology Development in China and Abroad

The knowledge of water cycle process is the basis for water science & technology development. “Water” being of multiple properties and functions with regard to environment, ecology, economy, society, and culture, etc. has surpassed any other natural resources in supporting socio-economic development and maintaining eco-system integrity and biodiversity. However, water resource is of duality of advantage and disadvantage. Too much water would result in floods and water logging and too little water would cause drought. Water pollution may lead to environmental degradation. The abnormal change of water quantity and quality could affect and even damage the ecosystem; to exploit and utilize water resource in the scientific and rational manner is beneficial to promoting the sustainability of water resource, whereas the irrational exploitation and use of water resource could exacerbate various water issues. Water cycle forms the “blood circulation system” of the biosphere. There are multiple bio-physical linkages between land, water, and ecosystem with water cycle being the basis to realize those links. However, human activities have interfered in the natural water cycle (by adding social water cycle on it) making great impact on those bio-physical links. It is worth to point out that water has played an extremely important role in environmental degradation, though it has been overlooked by many (Fu Bojie, et al., 2005).

Foresight of China’s Water Science & Technology Development till Year 2050

The water scientific and technological research both at present and in the future must address the above-mentioned, unprecedented, complex, diversified and comprehensive water issues. The roadmap for water science & technology development is put forward at macro level, based on the current reality and future prospective, in order to guide and promote the original innovation and integrated innovation of water science & technology, and the popularization and application of related technologies in different periods of time till year 2050 in China, to implement in the all-round manner the integrated water resources management, and to ensure the sustainable development of China’s economy and society: Five water issues, i.e. water resource, water environment, aquatic ecology, water disaster and water management will be discussed in this chapter; the country need development goals, science & technology issues; and key technologies will be presented for each water issue.