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    03 May 2018, Volume 73 Issue 5 Previous Issue    Next Issue
    Land Use and Ecosystem Services
    Spatio-temporal patterns and characteristics of land-use change in China during 2010-2015
    LIU Jiyuan,NING Jia,KUANG Wenhui,XU Xinliang,ZHANG Shuwen,YAN Changzhen,LI Rendong,WU Shixin,HU Yunfeng,DU Guoming,CHI Wenfeng,PAN Tao,NING Jing
    2018, 73 (5):  789-802.  doi: 10.11821/dlxb201805001
    Abstract ( 1685 )   HTML ( 77 )   PDF (3932KB) ( 3676 )   Save

    Land use/cover change is an important theme on the impacts of human activities on the earth systems and global environment change. National land-use changes of China during 2010-2015 were acquired by the digital interpretation method using high-resolution remotely sensed images, i.e. the Landsat8 OLI, and GF-2 remote sensing images. The spatio-temporal characteristics of land-use changes across China during 2010-2015 were revealed by the indexes of dynamic degree model, annual land-use changes ratio, etc. The results indicated that built-up land increased by 24.6×103 km2, while cropland decreased by 4.9×103 km2, and the total area of woodland and grassland decreased by 16.4×103 km2. The spatial pattern of land-use changes in China during 2010-2015 was concordant with that of the period 2000-2010. Specially, new characteristics of land-use changes emerged in different regions of China in 2010-2015. The built-up land in eastern China expanded continually, and the total area of cropland decreased, both at decreasing rates. The rates of built-up land expansion and cropland shrinkage were accelerated in central China. The rates of built-up land expansion and cropland growth increased in western China, while the decreasing rate of woodland and grassland accelerated. In northeastern China, built-up land expansion slowed down continually, and cropland area increased slightly accompanied by the conversions between paddy land and dry land. Besides, woodland and grassland area decreased in northeastern China. The characteristics of land-use changes in eastern China were essentially consistent with the spatial governance and control requirements of the optimal development zones and key development zones according to the Major Function-oriented Zones Planning implemented during the 12th Five-Year Plan (2011-2015). It was a serious challenge for the central government of China to effectively protect the reasonable layout of land use types dominated with the key ecological function zones and agricultural production zones in central and western China. Furthermore, the local governments should take effective measures to strengthen the management of territorial development in future.

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    Economic characteristics and the mechanism of farmland marginalization in mountainous areas of China
    LI Shengfa,LI Xiubin
    2018, 73 (5):  803-817.  doi: 10.11821/dlxb201805002
    Abstract ( 712 )   HTML ( 8 )   PDF (4106KB) ( 1206 )   Save

    Farmland marginalization has become the main trend of land-use change in the mountainous areas of China. Using the China Agricultural Production Costs and Returns Compilation (annual survey data of major agricultural production costs and earnings at national and provincial levels), this paper first analyzed the changes in the cost structure of agricultural production and the farmers' responses, under the context of the rapid rise in agricultural labor prices since 2003, and further compared the responses from the mountainous and plain regions. We found that farmers on the plains have reduced their labor input effectively through intensive use of agricultural machinery, which has minimized the impact of the increase in labor price. However, it is a severe challenge for farmers in the mountainous areas to use the same method due to the rough terrains. Thus, the agricultural labor productivity in these areas has increased relatively slowly, causing a widening gap in agricultural labor productivity between the two regions. With the rapid rise in labor costs, the marginalization of cultivated land in the mountainous areas is evident. In 2013, the profit of agricultural production in mountainous China, which takes maize cultivation as a representative, has fallen below zero. Since 2000, the land-use and land cover change in these areas has been characterized by the reduction of farmland area, reforestation, and the enhancement of the NDVI value. The high correlation between the NDVI change rate and the ratio of change in farmland (r = -0.70) and forest (r = 0.91) areas in mountainous areas at provincial level from 2000 to 2010, attests to the trend of farmland marginalization there. Finally, according to the analysis results, we summarized the mechanism of such marginalization against the backdrop of the rapid increase in the opportunity cost of farming and the sharp fall of agricultural labor forces. This study contributes to a deep understanding of the development process of farmland abandonment and forest transformation in the mountainous areas of China.

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    Spatial differentiation mechanisms of the pattern evolution of construction land development intensity in Northeast China
    LIU Yanjun,YU Huisheng,LIU Degang,ZHU Liyuan
    2018, 73 (5):  818-831.  doi: 10.11821/dlxb201805003
    Abstract ( 669 )   HTML ( 16 )   PDF (4715KB) ( 1444 )   Save

    The development intensity of construction land is a comprehensive reflection of the regional construction land development degree and its carrying capacity of regional population, economy and society. We construct a theoretical framework and measurement model for the development intensity of construction land. Taking 179 counties in Northeast China as the research object, we use the spatial autocorrelation and spatial variogram to explore the evolution of spatial-temporal differentiation of the development intensity of construction land. We also use the ordinary least square (OLS) model and the geographically weighted regression (GWR) model to analyze the influencing factors and the spatial differentiation mechanisms of the construction land development intensity. The research reveals the following points: (1) The development intensity of construction land shows an increasing tendency from 2000 to 2015 and its spatial variance is significant. The interactions and linkage effects of the development intensity of construction land among different counties are obvious, but the spatial distribution of the development intensity of construction land tends to be unbalanced, and the distribution pattern of the cold-hot spots is basically consistent with the global variation and spatial heterogeneity. (2) The spatial variance of the development intensity of construction land is mainly influenced by the intensity of government financial investment, the investment intensity of land use and the structure of industry development in 2000, while the level of economic development has become a new factor during 2005-2015. (3) There is a correlation between the four influencing factors and the spatial pattern of the development intensity of construction land, but the influence of the four influencing factors in different counties varies greatly.

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    Reconstruction of cropland area at the provincial level in the early Yuan Dynasty
    LI Meijiao,HE Fanneng,YANG Fan,LI Shicheng
    2018, 73 (5):  832-842.  doi: 10.11821/dlxb201805004
    Abstract ( 416 )   HTML ( 7 )   PDF (1880KB) ( 805 )   Save

    Reconstruction of regional historical land use and land cover change (LUCC) on the basis of historical documents is significant for regional eco-environmental effect studies and the enrichment of global historical land use datasets. By analyzing data recorded in historical documents, including Tuntian (cropland which was reclaimed by troops or farmers for military supplies) area, the number of Tuntian households, cropland area and the number of households, this paper proposed the conversion relationship between per household Tuntian area and per household cropland area. And a provincial cropland area estimation method of the Yuan Dynasty was designed. Then the method was used to reconstruct the provincial cropland area for AD 1290. The results are shown as follows: (1) Both per household Tuntian area and per household cropland area were high in north and low in south in the Yuan Dynasty, which was resulted from the differences of natural conditions and cropping systems in the south and north. And the geographical consistency signified that the allocation of per household Tuntian area takes reference to the local per household cropland area. (2) At the provincial level, there was some deviation between per household Tuntian area and per household cropland area. And the revision coefficients in the south and north were 1.23 and 0.65 respectively. (3) The cropland area of the whole study area in AD 1290 was about 535. 4×106 mu (Chinese area unit, 1 mu=666.7 m2), accounting for 57.8% of the north and 42.2% of the south. The territory land reclamation rate of the whole study area, the north, and the south were 6.8%, 6.6% and 7.1%, respectively. And per capita cropland area of the whole study area, the north, and the south were 6.7 mu, 15.6 mu and 4.1 mu, respectively. (4) The cropland was mainly distributed in the middle and lower reaches of the Yellow River (including Fuli area), the Huaihe River Basin (including Henan province), the middle and lower reaches of the Yangtze River (including Jiangzhe, Jiangxi, and Huguang provinces), and Yunnan province.

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    Review of landscape ecological risk and an assessment framework based on ecological services: ESRISK
    CAO Qiwen,ZHANG Xiwen,MA Hongkun,WU Jiansheng
    2018, 73 (5):  843-855.  doi: 10.11821/dlxb201805005
    Abstract ( 694 )   HTML ( 11 )   PDF (1091KB) ( 1352 )   Save

    During rapid urbanization, high-intensity human activities have imposed significant stress on the structure and services of the ecosystem, resulting in ecological risk. In recent years, rising landscape ecological risk assessments have provided a new perspective for studying the relationship between landscape patterns and the ecological process, which can effectively support ecosystem management. Through a comparison of the concepts of ecological risk, regional ecological risk, and landscape ecological risk, this paper primarily reviews the two main methods for landscape ecological risk assessment: landscape index method and risk "source-sink" method. We also discuss the research progress of landscape ecological risk based on ecological services. In addition, this paper puts forward a framework for landscape ecological risk assessment, ESRISK, based on ecosystem services. In this framework, ecological loss is represented by the degradation level of key ecological services, and risk probability is represented from the perspectives of terrain, artificial stress, ecological restoration, and landscape vulnerability. As for scientific rigor, the ESRISK framework is a comprehensive assessment of landscape ecological risk in the urban and regional development process, in which the landscape is the study object and ecosystem services serve as the medium. In terms of application prospects, the ESRISK framework is applicable to different assessment purposes, study areas, and scales. The framework could also potentially provide a more integrative paradigm for assessment of landscape ecological risk and support the determination of regional adaptive risk mitigation strategy, and the efficient allocation of limited resources. Lastly, we have submitted future research trends from four perspectives: (1) Focusing on long-term ecosystem service loss dynamics and incorporating tradeoffs and synergies among ecosystem services into the assessment framework; (2) strengthening the analysis of uncertainty in assessment results and risk decision scenario simulation; (3) revealing relationships between landscape ecological risk and landscape patterns, as well as multi-scale and nonlinear characteristics; and (4) integrating remote sensing and socioeconomic data to deepen risk assessment into vulnerability research.

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    Ecological service functions and value estimation of glaciers in the Tianshan Mountains, China
    ZHANG Zhengyong,HE Xinlin,LIU Lin,LI Zhongqin,WANG Puyu
    2018, 73 (5):  856-867.  doi: 10.11821/dlxb201805006
    Abstract ( 658 )   HTML ( 15 )   PDF (1416KB) ( 1133 )   Save

    The mountain glacier which has unique and irreplaceable ecological service function is the material basis and characteristic cultural foundation of the ecological environment and socio-economic sustainable development in arid area. However, there are few studies on estimating service function and value of ice regulating ecological environment and providing human welfare and so on. Based on the data of the first and second glacier catalogs, this research examines variations of glacier area and ice reserves of the Tianshan Mountains in China and constructs the ecosystem service function of mountain glaciers. And this study combines the unit area service function price method and equivalent factor method to evaluate the annual ecological service value of glacier in the research area. The research results are shown as follows: Firstly, in the last 40 years, glacier area decreases by 1274 km2, with the shrinking rate being 13.9%, and the annual average glacial reserve decreases by about 4.08×109 m3. And the increased area in glacier area of the high altitude (> 5200 m) may be due to the fact that the effect of glacier accumulation caused by precipitation enhancement is greater than that of glacier melting caused by temperature rise. Secondly, the annual ecological service value of glaciers in the research area is 60 billion yuan. And the value of climate regulation, hydrology regulation and freshwater resources supply contribute respectively 66.4%, 21.6% and 9.3% of the total value, and the average annual ecological service value of hydroelectric power is about 350 million yuan. Other regulation and the service function value is about 1.3 billion yuan. Finally, this study finds that supply of fresh water resources, physical production and the ecological regulating function account for the absolute contribution in the ecological system, through the comparative analysis of ice, forest, grassland and wetland ecosystem service value of different proportions of the total value, and the ecological service value of the glacier unit area is higher than those of other kinds of ecosystems. Therefore the purpose of the research is to improve the understanding of human beings on impact of glacier about the human welfare, the maintenance of ecological environment and other aspects, and provide a basis for policy making in cryosphere ecological security, environmental protection and sustainable use of resources for planning and management.

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    Change and tradeoffs-synergies analysis on watershed ecosystem services: A case study of Bailongjiang Watershed, Gansu
    QIAN Caiyun,GONG Jie,ZHANG Jinxi,LIU Dongqing,MA Xuecheng
    2018, 73 (5):  868-879.  doi: 10.11821/dlxb201805007
    Abstract ( 714 )   HTML ( 24 )   PDF (4515KB) ( 1177 )   Save

    Bailongjiang watershed in Gansu belongs to the upper reaches of Yangtze River water conservation area and the environment fragile area with frequent landslides and debris flow. Recently, the high-intensive human activities have caused the deterioration of natural systems. Therefore, it is of great significance to study the changes of ecosystem services and its trade-offs. In this paper, the spatial and temporal changes, spatial aggregation and the trade-offs/synergies between ecosystem services from 1990 to 2014 were quantitatively analyzed via the ecosystem service change index, spatial autocorrelation and correlation coefficient. The results showed that the ESCI ranges of the four typical ecosystem services types, namely, water yield, carbon storage, soil conservation and crop production were different from 1990 to 2014 with the difference of spatial distribution. There are spatial autocorrelation in four typical ecosystem services with obvious clustering characteristics. The cluster character and agglomeration of positive correlation of the local scale is strong, the agglomeration of the negative correlation type is low and scattered, and the spatial heterogeneity is significant. There is a negative correlation trade-offs between the two provisioning services (water yield and crop production), and positive correlation synergies between the two regulating services (carbon stocks and soil conservation). The relationships between the provisioning and regulating services have both trade-offs and synergies. There were both strong positive correlation synergies between water yield and soil conservation, and between water yield and carbon storage, and there were weak negative correlation trade-offs between soil conservation and crop production. As for the numerical relation, the trade-offs/synergies of ecosystem service changed differently in terms of Moran's I and correlation coefficient. There is significant heterogeneity of trade-offs/synergies between ecosystem services on the spatial pattern.

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    Climate Change
    Simulation of sedimentation processes in dry and wet seasons in the Xiaobeiganliu reach of the Yellow River
    SHAO Wenwei,WU Baosheng,WANG Yanjun,ZHANG Ruoyin
    2018, 73 (5):  880-892.  doi: 10.11821/dlxb201805008
    Abstract ( 719 )   HTML ( 19 )   PDF (1884KB) ( 786 )   Save

    Delayed response is one of important characteristics of self-adjustment in fluvial processes. Based on the mechanism of delayed response in fluvial processes, a delayed response model, considering the effects of water-sediment regime and the base level (Tongguan elevation), was developed to simulate the sedimentation processes in wet and dry seasons. The measured data in the period of 1960-2001 was used to estimate the parameters, and the measured data in the period of 2002-2015 was used to validate this model. Results showed that the proposed model could reasonably simulate the sedimentation processes in wet and dry seasons in the Xiaobeiganliu reach. This model performed better for cumulative sediment storage than single sediment storage in wet and dry seasons. Besides, this model also performed better for cumulative and single sediment storage in wet season than in dry season. Since the closure of Sanmenxia Dam, the sedimentation processes in wet and dry seasons in the Xiaobeiganliu has changed obviously in different periods during 1960-2015. Using this model, the contributions of water-sediment regime and the Tongguan elevation on sedimentation in different periods were analyzed. The sedimentation process was mainly affected by the Tongguan elevation in the period of 1960-1970(wet season) and 1960-1968(dry season). However, it was dominated by water- sediment regime after 1970(wet season) and 1968(dry season).

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    A review on the fully coupled atmosphere-hydrology simulations
    ZHAN Chesheng,NING Like,ZOU Jing,HAN Jian
    2018, 73 (5):  893-905.  doi: 10.11821/dlxb201805009
    Abstract ( 658 )   HTML ( 13 )   PDF (1433KB) ( 1598 )   Save

    Terrestrial hydrological process is an essential and very weak link in the global/regional climate models. In this paper, the development of research on the coupled atmosphere-hydrology simulations was analyzed, also the research trends and hotspots were identified by scientific literature analysis, and the challenges and opportunities in the coupled atmosphere-hydrology simulations are reviewed and summarized. The land surface processes in most of the existing climate models are mainly designed by the one-dimensional vertical structure, which lacks a detailed description of the two-dimensional hydrologic processes over specific basins, especially the parameterization of human activities on the underlying surface. In order to overcome the poor simulation on watershed hydrological processes derived by climate models, numerous studies were performed to investigate the feedbacks between hydrological processes and atmospheric processes, through coupling hydrological models with regional climate models. At present, improving the representation of hydrologic processes in land surface models and the development of global hydrological models have been the fundamental of investigating the feedbacks between terrestrial hydrology and atmosphere. Furthermore, the research on the coupling between hydrology and atmosphere has developed from the one-way coupling to the two-way coupling (also called fully coupled atmosphere-hydrology simulations). However, these studies on the fully coupled atmosphere-hydrology simulations were still immature and the fully coupled model needed further improvements, including further research on the matching methods of model coupling and system stability, research on effective scale transfer schemes, improvements on parameterization schemes and evaluation on parameter uncertainties, research on effective parameter transfer methods and improvements on regional applicability, as well as the coupled simulation of large-scale terrestrial hydrology and atmosphere at hyper-resolution with acceptable accuracy, and etc.

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    Spatiotemporal variations in maize phenology of China under climate change from 1981 to 2010
    QIN Ya,LIU Yujie,GE Quansheng
    2018, 73 (5):  906-916.  doi: 10.11821/dlxb201805010
    Abstract ( 746 )   HTML ( 11 )   PDF (4501KB) ( 1198 )   Save

    Based on the long-term phenology observation data of 114 agro-meteorological stations in the maize growing areas of China, the temporal and spatial differentiation characteristics of 8 consecutive phenology periods and the corresponding phenological stages length were quantitatively analyzed. The results showed that the average temperature and GDD (Growing degree days) during the growing seasons from 1981-2010 showed an increasing trend, and the precipitation and sunshine duration showed a decreasing trend in national scale. The maize phenology has changed significantly under the climate change background:Spring maize phenology was mainly advanced, especially in Northwest inland and Southwest mountain hills maize zone. While summer maize and spring-summer maize phenology were all delayed, and the delay trend of summer maize in the Northwest inland changed more than that in the Huanghuai plain. The variations of maize phenology changed the corresponding phenological stages length, the length of vegetative growth period (days from sowing date to tasseling date) of spring/summer/spring-summer maize all showed a trend of shorten in different degrees, and the corresponding reproductive growth period (days from tasseling date to mature date) showed a trend of extension. The whole growth period (days from sowing date to mature date) of spring maize were prolonged, but the whole growth period of summer/spring-summer maize shortened.

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    Comprehensive effect of climatic factors on plant phenology in Qinling Mountains region during 1964-2015
    DENG Chenhui,BAI Hongying,GAO Shan,HUANG Xiaoyue,MENG Qing,ZHAO Ting,ZHANG Yang,SU Kai,GUO Shaozhuang
    2018, 73 (5):  917-931.  doi: 10.11821/dlxb201805011
    Abstract ( 599 )   HTML ( 19 )   PDF (2868KB) ( 1121 )   Save

    Based on the data of phenological observation and daily meteorological records during 1964-2015, we studied the relationship between plant phenology variation and climate change in the Qinling Mountains region by using correlation and Partial Least Squares (PLS) regression analysis. The results showed that: (1) In the past 52 years, the climate of the study region presented a warming-drying trend at the start and the end of plant phenophase, and the warming trend at the start of phenophase is more significant than that at the end of phenophase, especially after the phenophase abrupt change around 1985. (2) The responses of the start and the end of phenophase to the change of climatic factors such as temperature, precipitation and sunshine varied differently. Before the period of phenophase abrupt change, the responses of phenophases were not significant to all the climatic factors except for the daily mean temperature. However, after the period of phenophase abrupt change, the response of phenophases was significant to all the climatic factors. The start of phenophase advanced by 3 d and the end of phenophase delayed by 12 d with the increase of the daily mean temperature by 1℃. The start of phenophase advanced by 1.3 d with the decrease of the accumulated precipitation by 1 mm, and the end of phenophase delayed by 1 d with the increase of the accumulated precipitation by 1 mm. The start of phenophase advanced by 4.3 d and the end of phenophase delayed by 18.3 d with the increase of daily mean sunshine hours by 1 h, respectively. (3) There is a lag effect for the responses of the start and the end of phenophase to climate change. The time-lag was about 1-2 months for air temperature and about 1-3 months for the pre-period accumulated precipitation at the start of phenophase, respectively. No lag effect on the start of phenophase was observed for the sunshine hours. As related to the end of phenophase, the time-lag was about 1-3 months for the air temperature and about 1-2 months for the sunshine hours, respectively. No lag effect on the end of phenophase was found for the precipitation. (4) Both the start and the end of phenophase were jointly affected by the climatic factors, in which the air temperature was the predominant factor. Especially, the rise of the daily mean temperature plays a dominant role in advancing the start of phenophase and delaying the end of phenology.

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    Spatial-temporal characteristics of ice phenology of Qinghai Lake from 2000 to 2016
    QI Miaomiao,YAO Xiaojun,LI Xiaofeng,AN Lina,GONG Peng,GAO Yongpeng,LIU Juan
    2018, 73 (5):  932-944.  doi: 10.11821/dlxb201805012
    Abstract ( 730 )   HTML ( 20 )   PDF (5329KB) ( 1534 )   Save

    Lake ice phenology is considered a sensitive indicator of regional climate change. We utilized time series information of this kind extracted from a series of multi-source remote sensing (RS) datasets including the MOD09GQ surface reflectance product, Landsat TM/ETM+ images, and meteorological records to analyze spatiotemporal variations of ice phenology of Qinghai Lake between 2000 and 2016 by applying both RS and GIS technology. We also identified the climatic factors that have influenced lake ice phenology over time and draw some conclusions. First, data show that freeze-up start (FUS), freeze-up end (FUE), break-up start (BUS), and break-up end (BUE) on Qinghai Lake usually occurred in mid-December, early January, mid-to-late March, and early April, respectively. The average freezing duration (FD, between FUE and BUE), complete freezing duration (CFD, between FUE and BUS), ice coverage duration (ICD, between FUS and BUE), and ablation duration (AD, between BUS and BUE) were 88 days, 77 days, 108 days and 10 days, respectively. Second, while the results of this analysis reveal considerable differences in ice phenology on Qinghai Lake between 2000 and 2016, there has been relatively little variation in FUS times. Data show that FUE dates had also tended to fluctuate over time, initially advancing and then being delayed, while the opposite was the case for BUS dates as these advanced between 2012 and 2016. Overall, there was a shortening trend of Qinghai Lake's FD in two periods, 2000-2005 and 2010-2016, which was shorter than those seen on other lakes within the hinterland of the Tibetan Plateau. Third, Qinghai Lake can be characterized by similar spatial patterns in both freeze-up (FU) and break-up (BU) processes, as parts of the surface which freeze earlier also start to melt first, distinctly different from some other lakes on the Tibetan Plateau. A further feature of Qinghai Lake ice phenology is that FU duration (between 18 days and 31 days) is about 10 days longer than BU duration (between 7 days and 20 days). Fourth, data show that negative temperature accumulated during the winter half year (between October and the following April) also plays a dominant role in ice phenology variations of Qinghai Lake. Precipitation and wind speed both also exert direct influences on the formation and melting of lake ice cover and also cannot be neglected.

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    Earth Surface Process
    The trends of streamflow and sediment and their driving factors in the middle reaches of the Yellow River
    SUN Qian,YU Kunxia,LI Zhanbin,LI Peng,ZHANG Xiaoming,GONG Junfu
    2018, 73 (5):  945-956.  doi: 10.11821/dlxb201805013
    Abstract ( 470 )   HTML ( 31 )   PDF (2872KB) ( 912 )   Save

    As streamflow and sediment of the coarse sand area in the middle reaches of the Yellow River have experienced considerable change under the background of climate change and intensified human activities in recent years, it is of great importance to conduct research on their driving factors to predict future streamflow and sediment discharge of the Yellow River. We used annual precipitation, annual streamflow volume, and annual sediment discharge data from 15 hydrological stations located in the coarse sand area of the middle reaches of the Yellow River from 1956 to 2010. The Mann-Kendall trend test, Pettitt change point test, generalized additive model for location, scale, and shape model (GAMLSS), and comparison of cumulative slope change rate were applied to analyze the variation characteristics of these hydrological variables and to determine the driving factors of annual streamflow volume and annual sediment discharge. The results of the analyses are as follows: (1) The Mann-Kendall trend tests showed that annual precipitation demonstrated a non-significant decreasing trend at the 5% significance level, whereas annual streamflow volume and sediment discharge exhibited significant decreasing trends in the study area; (2) The Pettitt change point tests showed that the abrupt change of time-points for annual streamflow volume and sediment discharge occurred around 1972, 1985, and 1996; (3) The GAMLSS results indicated that the mean values of annual precipitation did not change with time, but the variance of annual precipitation showed a decreasing trend in all study areas; (4) The comparison of cumulative slope change rate showed that the influences of human activities on annual streamflow volume and sediment discharge were greater in the Kuye River basin than that in the Wuding River basin. Analyzing the driving factors of changes in annual streamflow volume and sediment discharge provides theoretical support for the rational allocation of water resources in the coarse sand area of the middle reaches of the Yellow River.

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    Optically stimulated luminescence dating of moraines in East Altay Mountains, Xinjiang
    JIA Binbin,ZHOU Yali,ZHAO Jun
    2018, 73 (5):  957-972.  doi: 10.11821/dlxb201805014
    Abstract ( 459 )   HTML ( 8 )   PDF (4361KB) ( 636 )   Save

    The glacier is one of the most positive external forces for shaping the landscape of earth surface in alpine region. The geochronology study of glacial stratigraphy can provide insightful information about the ancient glacier process, which is sensitive to climate change. Compared to the sediments of ice lake and ice water terrace with complex material source, moraine is the direct product of glacial movement. Consequently, it can also reflect the glacier events that occurred in the past. The accurate dating of moraine can provide chronology evidence for improving the understanding of reconstruction of climate change patterns. The Altay Mountains is one of the major mountain ranges for understanding Quaternary glaciation in northwestern China. Most of the studies have focused on western Altay Mountains, Xinjiang. However, the chronology of the moraines in its eastern section is not well studied. In this study, OSL dating technique method was applied to determine the ages of the glacial moraine deposits of coarse grained quartz (90-125 μm) in the East Altay Mountains. According to analysis of the frequency distribution of De value and De(t) plots, most of the moraine samples showed partial bleaching. Therefore, the first-order kinetic equation was used to separate the CW-OSL curve into three component exponentials (fast, medium and slow components) and the fast components were used to determine these equivalent doses. The OSL dating results of moraines in East Altay Mountains deposited seperately in 32.33 ka, 16.07 ka, 8.41-8.07 ka, 6.83-6.48 ka and 4.62 ka. This implied that the glacier development process was identified with MIS3, MIS2, 8.2 ka Cold Events, Holocene Optimum and Neoglaciation, respectively. Observably, moraine can occur with glacial advance or recession during the warm or cold climate episodes, while the development of glaciers in the Altay Mountains was closely related to global climate change. This study demonstrates the successful application of quartz OSL with fast component signal to glacial sediments from the Altay Mountains. Furthermore, it can complement the geochronology data for moraine sedimentary records to reveal the glacier evolution history in the whole Altay Mountains region since 32 ka BP.

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    A quantitative study on the karst geomorphic evolution of Shilin county in Yunnan province of China based on Strahler hypsometric analysis
    LI Yuhui,DING Zhiqiang,WU Xiaoyue
    2018, 73 (5):  973-985.  doi: 10.11821/dlxb201805015
    Abstract ( 590 )   HTML ( 12 )   PDF (3957KB) ( 1014 )   Save

    Based on the relationship between the heterogeneous karst geomorphic structure and the integral protection and utilization of the karst reserve, Strahler hypsometric (area-altitude) analysis is used to quantify the karst geomorphic evolution of Shilin county in Yunnan province of China. The Strahler hypsometric values of the whole area (catchment), elevation zones' terrains and their depressions are measured. Supported by Geographical Information System (GIS) technologies, these Strahler hypsometric measurements are designed based on the development mechanism of karst landform, which includes height-reduction horizontal erosions and depth-increase vertical erosions. The results indicate that landscapes with different development features on various topographic surfaces have different Strahler values. The differences and patterns could be used as an indicator to reflect the evolution of landscapes. Shilin county's geomorphic structure has four levels of terrains with different altitudes at the late period of mature stage. Such a structure is formed from the decomposition of the monadnock karst planation plateau with an interplay of the faults and the erosion base of Bajiang river. Shilin county has a rejuvenating geomorphic structure, which is heterogeneous from other geomorphic structures of the same stage. The terrain above 2100 metres of altitude is the structural erosion karst plateau middle mountain evolved from the monadnock karst planation plateau with less depressions. The terrain with an altitude of 1900-2100 metres shifts from the monadnock karst planation into the monadnock karst plateau depressions and cone karst depressions with less underground rivers. The elevation zone with an altitude of 1700-1900 metres is a karst hill slope. The zone is composed of the vertical layer structure of the Stone Forest and the horizontal terrace geomorphic structure. The vertical layer structure of the Stone Forest comprises stone forest remains, pinnacle-shaped stone forest, buried stone forest, and baked stone forest. The horizontal terrace geomorphic structure contains karst hills, stone forest, karst depressions, underground rivers, karst springs, and Bajiang river-basin. The landform is shaped from the mixed functions of vertical and horizontal karst processes, with water resources produced and water-soil eroded off. This is the theoretical foundation for the comprehensive protection and utilization of the Stone Forest reserve.

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