From the perspective of achieving sustainable development in the world and building a community with a shared future for humankind in the "Anthropocene", and considering the complexity of the Earth's surface system, various disasters facing humanity, and future challenges of resource shortages and environmental risks, we proposed the development of "geographical synergy"—the mechanism, process and dynamics of the Earth's surface system and regional sustainability—in order to realize the transformation of geographical research from the explanation of human-environment relationship to the design of human-environment synergy. We discussed the scientific and technological questions of modern geography from the perspectives of integrating natural and social units, natural resources and natural disasters, achievements and faults of humans, and coupling of dynamic and non-dynamic processes and systems. We proposed the metrics of "consilience degree" as a measure of the complexity of integrated disaster reduction system based on the understanding of disaster system and the mechanism, process and dynamics of hazard and disaster formation. Using the principles of synergetic tolerance, synergetic constraint, synergetic amplification and synergetic diversification, we proposed to build an integrated disaster risk governance consilience model under the leadership of governments and with enterprises as the main body and the full participation of communities, with multiple optimization objectives of social consent maximization, cost minimization, welfare maximization, and risk minimization. Finally, we elaborated on the synergy of human and nature through "changing nature appropriately", with a case study on the Dujiangyan irrigation system, which enabled the win-win pattern of disaster reduction and benefit making.
According to the land supply results obtained from http://www.landchina.com/, this paper explored the spatio-temporal characteristics of state owned construction land supply of counties in China from 2010 to 2015 by using the spatial distribution of gravity-center, locational Gini index and hot spot analysis, and then analyzed the influencing factors of land supply of regions in different development phases based on panel data models. We found that land supply has experienced a process of increasing first and then decreasing, and spatial agglomeration degree, hot spot and sub-hotspot zones of land supply in counties were in general diffusion during the study period. Due to the implementation of "Western Development Strategy", "Aiding Xinjiang" and "Rise of Central China Plan", spatial distribution of gravity-center of land supply in counties moved evidently westward. The land supply was concentrated within the urban agglomerations. The administrative hierarchy of prefecture-level cities with counties was closely related to the land supply scale. In other words, the higher the administrative level of prefecture-level cities is, the larger the average land supply of counties is. There were differences in the total supply land size change and average land supply structure from region to region in different development stages. In general, the regions with high development stages need more construction land. Public finance expenditure, fixed asset investment, secondary industry growth rate, tertiary industry growth rate, growth rate of population size and per capita GDP have different effects on the land supply of regions in different stages. Among them, investment including public finance expenditure and fixed asset investment plays a critical role in promoting the land supply of regions in different development stages.
Changes of rice production in Southern China are crucial to national food security. This study employed Landsat images to map the distributions of paddy rice cropping systems in Southern China in 1990 and 2015, and then explored the impact of rice multiple cropping index changes on grain production capacity. The results indicated that: (1) From 1990 to 2015, the multiple cropping index of rice decreased from 148.3% to 129.3%, and the loss area due to conversion of double cropping rice to single cropping rice ("double to single") was 253. 16×104 hm2. The area with most dramatic changes was located in the Middle-Lower Yangtze Plain. The rice cropping systems in Southern China showed a change pattern of "double cropping rice shrinkage and single cropping rice expansion" from north to south. (2) From 1990 to 2015, "double to single" led to a reduction of 6.1% and 2.6% in rice production and grain production, respectively. Hunan and Jiangxi, located in the main rice producing areas, as well as Zhejiang with better economic development, had a large reduction in rice production due to "double to single", all exceeding 13%. (3) The grain production capacity of "double to single" paddy field is equivalent to that of 223.3×104 hm2 of newly reclaimed cultivated land. The equivalent newly reclaimed cultivated land is 54% of the total newly reclaimed cultivated land through the land consolidation project during 2001-2015, as well as 1.7 times the target of the newly cultivated land goal for the national land consolidation plan (2016-2020). Making full use of the "double to single" paddy field can save approximately 167.44 billion yuan newly reclaimed cultivated land costs. Therefore, instead of pursuing low-quality "new" arable land, it is better to make full use of the existing high-quality "old" arable land. The government should change the assessment method of cultivated land balance, and incorporate the sown area increased by improving multiple cropping index into the cultivated land compensation indicator.
Having arisen as a national strategy and institution, the Major Function Zones Planning (MFZP) will play an active role in guiding and restraining China's long-term spatial development pattern. From the perspective of region uniqueness, it is critical to reveal the genesis (formation and evolution) and feedback (identification and planning) principles for MFZP. This paper takes Chongqing Municipality, a typical provincial unit in Southwest China, as an example to identify the suitable spatial pattern for MFZP by Territorial Space Development Conditions Comprehensive Evaluation (TSDCCE). Depending on perceptual observation of suitable pattern, this paper makes a dominant factors restriction hypothesis, defines the topography and urban location as the dominant factors, and then validates the correlation between dominant factors and Major Function-Oriented Zoning (MFOZ) index system. Then, based on the above analysis results, it discusses the restrictive and spatial stability mechanism originated from dominant factors for MFOZ. The results show that: (1) The spatial pattern of suitability is clear in terms of development or protection. The areas suitable for urbanization are mainly metropolitan regions and some surrounding counties, and sub-regional centers (Wanzhou and Qianjiang) also have relatively high suitability. The areas suitable for ecological protection are mainly located in the northeast and southeast of Chongqing, including Daba mountain area, Three Gorges Reservoir area and Wuling mountain area. (2) Topography and urban location factors dominate the MFOZ spatial pattern in this region. Regression analysis showed that more than 70% of the correlation between the MFOZ index and the topographic factor reached a significant level, while the correlation between the MFOZ index and urban location factor is over 40%. The significant levels (R2) of correlation between the weighting index (topography and urban location) and MFOZ flag variables (A and B index) are more than 0.8; The geographic detector finds that the topography's restriction on MFOZ indicators and urban location factors on that are 9 and 7, respectively, which reaches 0.05 significant level and the explanatory degrees for indicators A and B are about 70% and 60%, respectively. Then combining topography factor and urban location factor, it finds that restriction is obvious and the explanatory degrees for A and B are up to about 90%. (3) The spatial stability mechanism is shown in two aspects: one is the stability transfer mechanism based on the dominant factor's restriction, which is called objective stability; the other is the local relativity index system and the internal cancellation mechanism of the algorithm, namely, subjective stability. The coordination of the two mechanisms verifies the regional adaptability and correctness of the zoning technology system.
The ratio of transpiration to evapotranspiration (T/ET) is a key parameter for quantifying water use efficiency of ecosystems and understanding the interaction between ecosystem carbon uptake and water cycling in the context of global change. The estimation of T/ET has been paid increasing attention from the scientific community in recent years globally. In this paper, we used the Priestly-Taylor Jet Propulsion Laboratory Model (PT-JPL) driven by regional remote sensing data and gridded meteorological data, to simulate the T/ET in forest ecosystems along the North-South Transect of Eastern China (NSTEC) during 2001-2010, and to analyze the spatial distribution and temporal variation of T/ET, as well as the factors influencing the variation in T/ET. The results show that: (1) The PT-JPL model is suitable for the simulation of evapotranspiration and its components of forest ecosystems in Eastern China, and has relatively good stability and reliability. (2) Spatial distribution of T/ET in forest ecosystems along NSTEC was heterogeneous, i.e., T/ET was higher in the north and lower in the south, with an averaged value of 0.69; and the inter-annual variation of T/ET showed a significantly increasing trend, with an increment of 0.007/yr (p < 0.01). (3) Seasonal and inter-annual variations of T/ET had different dominant factors. Temperature and EVI can explain around 90% (p < 0.01) of the seasonal variation in T/ET, while the inter-annual variation in T/ET was mainly controlled by EVI (53%, p < 0.05).
Quantitative research on the effects of ecological conservation projects and climate variations on vegetation changes is vital to the ecological benefit evaluation of ecological conservation projects, and has important implications for sustainable ecological rehabilitation management strategies in the source region of the Yangtze River. Based on the normalized difference vegetation index (NDVI) data and meteorological data during 1982-2015, this paper examines the temporal and spatial variations of NDVI; constructs back propagation artificial neural network (BPANN) model to simulate the responses of NDVI to climate factors; and quantifies the effects of ecological conservation projects and climate variations on vegetation changes at the annual and seasonal scales in the source region of the Yangtze River. The results indicate that: (1) Because of the effects of ecological conservation projects and climate variations, vegetation degradation curbed in the source region of the Yangtze River. (2) NDVI increased greatly near the Tongtian River located at relatively low altitudes. Minor increases in NDVI were observed near the Tuotuo and Dangqu rivers located at relatively high altitudes. (3) A time lag (about 1-2 months) existed between NDVI and major climate factors in the source region of the Yangtze River. The goodness of fit of the BPANN model shows that the simulation accuracy is relatively high. The model can be used to simulate the responses of NDVI to climate variations. (4) Ecological conservation projects exerted a slightly greater impact on NDVI changes than they did on climate variations at the yearly time scale (58.5% and 41.5%, respectively). During growing season, ecological conservation projects also exerted a slightly greater impact on NDVI changes than they did on climate variations (63.3% and 36.7%, respectively). During non-growth season, climate variations are the key factor affecting vegetation growth in the source region of the Yangtze River (52.8%). The research results provide a basis for scientific decision-making about the vegetation ecosystem rehabilitation, management and utilization strategies in the source region of the Yangtze River.
Based on the MOD09A1 and MOD16A2 datasets with a temporal resolution of 8 days during a period from 2001 to 2016, Drought Severity Index (DSI) was quantified to characterize spatiotemporal distribution of droughts of different drought intensities. The correlation coefficients were quantified between drought-affected cropland area and the climatic winter wheat yield. In addition, relevant impacts of droughts with different drought intensities were investigated on the winter wheat yield during different growing periods. The results show that: (1) drought regimes during 2001-2016 showed a declining trend in terms of drought intensity at annual and inter-annual scales. The most severe drought occurred during 2001-2002 while regional and intermittent droughts could be observed during 2003-2010, and were alleviated during 2011-2016 with persistent wetting tendency thereafter. In terms of annual drought distribution, droughts occurred mainly in spring and autumn, some occurred in summer and few droughts in winter; (2) Generally, in terms of the spatial distribution of droughts, central and northern Hebei, southern Henan, Anhui and Jiangsu, and eastern Shandong provinces were dominated by frequent droughts though droughts were in decreasing trends; (3) analysis results concerning effects of droughts on winter wheat yield show that the incipient drought during the winter period can promote the winter wheat yield, while in the milking stage of the winter wheat, occurrence of droughts may decrease crop yield. The mild drought potential has significant effects on winter wheat yield during the ripening interval, while the moderate drought occurs during flowering, milking and ripening periods can have a significant impact on the winter wheat yield. Meanwhile, droughts with higher degree of intensity will have more significant impacts on winter wheat at its earlier growing season. In addition, water shortage due to drought effects during planting periods will reduce the yield of winter wheat, and severe and extreme droughts in particular. Therefore, it is of great merits in quantification of impacts of droughts with different intensities on winter wheat yield in different growing seasons, and it has important theoretical and practical significance for the planning of irrigation and the increase of soil moisture in the study region.
The water diversion scheme is important for the sustainable development of the economic, social and ecological environment in different parts of the basin, especially for the rivers in arid areas. In order to curb the trend of ecological degradation in the lower reaches of the Heihe River, the Heihe River water diversion scheme, approved in 1997 by the Chinese government, was carried out in 2000. With the implementation of the water separation scheme, the allocation of domestic water, production and ecological water tends to be reasonable, and the trend of ecological environment deterioration has been relieved. However, there are still queries on the rationality of water diversion schemes because it is difficult to complete water diversion indicators in wet years. Therefore, it is necessary to comprehensively analyze the implementation of the water diversion scheme and evaluate its adaptability in the Heihe River under the changing background. In this paper, based on the analysis of the impact of water diversion scheme, the technical characteristics and adaptability of water diversion under the changing background were analyzed. By establishing water resource allocation model of the Heihe River, the implementation of water resource allocation under different water demands and the operation of Huangzangsi (Huangzang Temple) Reservoir for long-time series (from 1958 to 2012) were simulated, and then the adaptability of water diversion schemes was analyzed. The result shows that the Heihe River water diversion scheme cannot meet the requirements of water diversion under the current condition due to the changes of economic society and river connectivity in the Heihe River basin. Water diversion indicators can be accomplished when the area of farmland in the middle reaches decreases to the level of 2000 and the construction of Huangzangsi Reservoir is finished, but there is still over exploitation of groundwater in the middle reaches. In conclusion, "97" water diversion plan is inadaptable to the current situation to some extent on the basis of the economic, social and hydrologic conditions of the Heihe River in the mid-1980s.
Based on the data of relative soil moisture obtained from 653 agricultural meteorological stations in China during the period of 1993-2013, the spatial and temporal differentiations of relative soil moisture in China's farmland were analyzed and discussed by using geostatistical methods. The results show that the relative soil moisture of China's farmland has fluctuated and increased since 1993, exceeding 60% in general. The distribution area has been expanding to the north and west with the summer monsoon since mid-April, and in late October, the region began to shrink to the east and south. The value of relative soil moisture increases with the increase of soil depth, and the distribution of farmland in high-value area increases with the increase of soil depth. The relative soil moisture of farmland increases fastest in summer and autumn, and the range of change decreases with the increase of soil depth. There is a strong positive correlation between relative soil moisture and precipitation. Relative soil moisture has a strong negative correlation with potential evaporation and temperature. The annual mean value of relative soil moisture in paddy field is higher than that in dry land, and the difference between the annual mean values of relative soil moisture of two types of farmland increases with the increase of soil depth.
There are 66 tributaries in the Three Gorges Reservoir (TGR) area, where most of them witnessed pronounced deposition in mouth reach since the impoundment of the TGR. The lasting sedimentation may lead to the formation of outlet bar at mouth section, which generated adverse effects on storage capacity of the TGR and navigation of tributaries. This paper, taking the Modao Creek and Xiangxi River as examples, examines the characteristics and causes of sediment deposition in their mouth sections based on detailed observation data such as flow, sediment, cross section and channel topography. The results show that: (i) after the impoundment of the TGR, a large amount of deposition occurred in its tributary mouth. The maximum deposition thickness of Modao Creek and Xiangxi River mouth sections exceeded 10 m from 2004 to 2017. Deposition was basically within the range of 15 km of the mouth section, and the strong depositing zone was focused in the reach of about 5 km away from the river mouth. The sediment deposition in the river mouth mainly occurred in the initial operation period of the TGR, and slowed down particularly since 2010 when the cascade hydropower stations in the middle and lower Jinsha River began to operate; (ii) the weakened hydrodynamic condition in dry season at the tributaries mouth, and the significantly reduced sediment-carrying capacity, are the fundamental causes in responsibility to the intense deposition. Sediment deposited at Modao Creek and Xiangxi River mouth sections mainly came from the mainstream in the form of inverted flow, and partially came from their own basin. The deposition range of sediment and its influence on channel morphology were related to local river regime; (iii) Optimized operation of the TGR since 2010 has not affected the sediment deposition in the tributaries mouth. Decreased sediment concentration in mainstream and tributaries and the maintenance the low water level in flood season do not support the formation of outlet bar of tributaries in the TGR.
The Yellow River Delta is one of the most famous river deltas in the world. Since Xue and Cheng (1989) first systematically proposed the spatio-temporal distribution of ten Holocene superlobes in the delta, this hypothesis remains unchanged in the last three decades. To redefine the characteristics of sedimentary evolution and spatial-temporal distribution of Lijin superlobe in the Yellow River Delta, 4 boreholes with a length of 20-30 m were obtained in the coastal plain of South Bohai Bay. Combined with the achievements of previous boreholes in the study area, the stratigraphical data and AMS14C dating results in these boreholes revealed that the river channel and flooding plain dominated the study area in the early Holocene. It turned to be saltmarsh, tidal flat and shallow sea environments in the chronological order when the Holocene transgression reached the study area. Delta progradation began as the sea level decelerated, and was finally capped by the terrestrial sediments in this area. The ancient river channel of the Yellow River might enter the sea by the southern area of Huanghua during 9000-8000 cal a BP. After ~8000 cal a BP, the main river channel shifted southward between Binzhou and Huiming, which led to the development of Lijin superlobe from 7000 cal a BP to 5500 cal a BP. The northern boundary of Lijin superlobe may link Mashanzi with Yangxin while the southern one was located between Guojingzi and Mihe River. The ancient Yellow River mouth might return to Huanghua after ~5500 cal a BP and formed the Huanghua superlobe ranging from 5500 cal a BP to 3500 cal a BP. The Yellow River changed its main course to Tianjin earlier than 3500 cal a BP and might turn back to Qikou in Hebei province after ~700 BC.
Central Asia, consisting of extended arid and semiarid areas, is one of the major sources of global dust and aerosol in the Northern Hemisphere. Dust emission, transportation and deposition over the region have received an increasing interest. Loess deposits, as a geologic record of dust, enable the possibility of archiving dust variabilities over the past, and give insights into the underlying mechanisms of dust activities. Here, we examined the grain size data of two late Pleistocene loess-paleosol sequences, named Nilka (NLK) and Qingshuihe (QSH), in the Ili Basin, eastern Central Asia, with focus on intervals with the highest sedimentation rates in both loess sections. Both sites are located on the south slope of the northern Tianshan Mountains, but represent different topographies and climate conditions. Parametric curve-fitting and hierarchical cluster analysis techniques were applied to partition the whole spectrum of the measured grain size distributions and provided a more reliable and more representative statistical descriptors. The end members unmixed under distant eolian dynamics were used to reveal the dust accumulation processes in the Ili Basin in detail. The results suggest that the Ili loess mainly consists of distal and proximal sediments, with the high-level westerlies and the meso-scale regional winds as the transport agents respectively. Distal clayed mineral particles transported by the high-level westerlies can contribute to the loess sediments from the eastern basin due to the wet deposition, where precipitation is high. Nevertheless, this is not true for the western part of the basin where the clay fractions are difficult to deposit. Proximal sediments dominate the Ili loess, and the grain-size composition and formation process of the Ili loess can be dependent on the availability of the local particulate materials with different sizes. Additionally, the floating dust derived from "non-dust storm processes" (after sand and dust storms) has significant impacts on the loess formation during periods of decreasing dust storm frequency. Whereas sparse vegetation is likely to create favorable conditions to the resuspension of the floating dust components when dust storms occur frequently. A conceptual model about dust accumulation in the Ili Basin is proposed based on the above results.
The sedimentary environments of the Yangtze Estuary riverbed have changed a lot with the construction of water conservancy projects in the drainage basin and the estuary, which have significantly influenced the river regime evolution and accretion/erosion of the estuary riverbed. However, less has been reported on detailed sedimentary characteristics of the current estuary riverbed, which restrains further evaluation on the impact on both hydrology and sedimentology of the Yangtze Estuary. Therefore, based on the large-scale surface sediment samples and associated flow-sediment data collected during September 2015, we analyzed the sedimentary characteristics in the seven riverbeds within the estuary and discussed the influencing factors and mechanisms. The particle sizes of the sediment samples were analyzed by Model LS-13320 Coulter laser particle size analyzer and the types of the surface sediments were classified by Folk’s classification. The results are shown as follows. The riverbed sediments of the whole estuary is dominated by sandy silt and silty sand. The coarsest surface sediments are observed in the outer estuary of north branch/north channel above 10 m and upper north/south branch, while the finest surface sediments are found in the north passage, lower south passage and the outer estuary of north/south passage deeper than 5 m. Generally, the particle sizes of the river sediments are coarser in the main channels and finer on the shoals, and decrease from west to east and from north to south. The lateral sedimentation distribution characteristics are affected by the sediment transportation and deposition in ebb and flow process. The longitudinal sedimentation distribution reflects the differences of the sedimentary environment strengthened by the wind wave. The sediments in the north branch are coarsened remarkably due to the intense north wind wave action. The difference of sediment origins is the factor leading to deviation of the sedimentary environment. The sediment in the south branch and upper south channel show a characteristic of riverine sediments, while the sediments in the north channel, north passage and south passage show a mixture of riverine and marine sediments. Sediments in the outer estuary mainly provide fine-grained particles to the inner estuary.
The application code of the National Natural Science Foundation of China (NSFC) is the guide for forming a reasonable funding pattern of basic research, fostering the balanced and coordinated development of disciplines, encouraging interdisciplinary disciplines and developing new research directions. In this paper, we have firstly carried on the historical evolution for application code system of geography discipline since the establishment of the NSFC (1986). Then more attentions were paid to analyze the design characteristics of the geography application code system in the direction of water, soil, ecosystem services, environment and the human-land relationship evolution in the new period, and prospect the impact on the funding pattern of basic research in the future.
