Far from major zones of human pollution, the widely developed lakes on the Tibetan Plateau are ideal regions to evaluate global and regional impacts caused by human activities. Based on the reliable dating, they can provide historical records of human pollution. Heavy metal is one of the most harmful pollutants, and is harmful to biological environment and people's health due to its degradation-resistancy. Environmental magnetism characterized by its sensitivity, facility and non-destructiveness, has been applied widely in estimating increased heavy metal pollution in different environmental systems. However, there lacks the relevant research in lake sediments on the Tibetan Plateau. Thus, we conducted a systematic environmental magnetic investigation of lake sediments in the Qiangyong Co Lake, southern Tibetan Plateau to explore the relevance between magnetic minerals and heavy metal (Hg). Results indicate that magnetic mineral species constituted by four different components (C1, C2, C3, C4) remain stable during 1899-2011 AD, but the component C1 (hematite) increased continuously with the corresponding decrease of component C2 (goethite). In contrast, components C3 and C4 (magnetite) have no significant changes. The correlation between SIRM and Hg differs from that between χ_lf and Hg, probably because SIRM and χ_lf are affected by different factors of complex magnetic mineral species (four different components). But the component C1 is correlated well with both Hg content and climate warming of the Tibetan Plateau. This indicates that Qiangyong glacier (the main recharge source of Qiangyong Co Lake) melt faster upon the Tibetan Plateau warming, and the accumulated Hg in glacier and cryoconite were released again. During the processes, C1 (hematite) with large specific surface area absorbs Hg, and is transported to the Qiangyong Co Lake. This research indicates that the magnetic properties of the Qiangyong Co Lake are excellent environmental proxies, which can provide a new method to study the process of Hg deposition in lakes on the southern Tibetan Plateau.

The Tibetan Plateau is one of the most sensitive regions to global climate change. It is of important theoretical significance to explore the effect of soil moisture changes on near-surfaceair temperature for the study of the water cycle of the Tibetan Plateau and its impact on the surrounding climate and environment. Based on the NCEP-CFSR dataset, this paper reveals the spatial-temporal pattern of soil moisture content in different seasons and different vegetation zones on the Tibetan Plateau, the response and coupling of soil moisture and evaporation rate, and the impact of soil moisture on near-surface air temperature through evapotranspiration. The results show that: (1) The spatial pattern of soil water on the Tibetan Plateau is basically similar in different seasons, showing a decreasing trend from southeast to northwest and the spatial characteristics of drying in humid regions and wetting in arid regions; (2) The soil moisture in most parts of the Tibetan Plateau is in a transitional state, in which the southern and southeastern parts of the plateau are in a state of transition throughout the year, while the soil moisture in the Qaidam Basin is almost in a dry state all the year round; (3) The sensitivity of the near-surface air temperature to soil moisture is the weakest in winter, but the strongest in summer with weak spatial difference, which is negative feedback in winter, spring and summer. Moreover, the sensitivity of air temperature to soil moisture varies greatly in different vegetation coverage areas. This study has important theoretical significance for further exploring the regional water cycle and its effects under the coupled land-atmosphere state and the changing environment of the Tibetan Plateau.

The glacier mass balance (GMB) is an important link between climate and water resources, which has remarkable regulation functions for river runoff. The research, using MOD11C3, TRMM 3B43 and other multi-source remote sensing data to drive the degree-day model, simulates the GMB processes and analyzes the recharge of glacial meltwater to runoff in the Manas River Basin (MRB) during 2000-2016. The results show that: (1) By constructing the temperature and precipitation inversion model, the accuracy of the meteorological remote sensing data can be effectively corrected, and the characteristics of climate change in the glacial region can be well described after downscaling. The annual average temperature and precipitation in the glacier area were -7.57 ℃ and 410.71 mm, respectively. The place at an altitude of 4200 m is a severe climate change zone. Above 4200 m, the temperature drop rates and precipitation gradients were -0.03 ℃/100 m and -2.66 mm/100 m, respectively; while below 4200 m, they were -0.57 ℃/100 m and 4.8 mm/100 m, respectively. Besides, at a higher altitude of 4700 m, the precipitation increased by 5.17 mm/100 m. (2) During the study period, the glaciers in the basin continued to be in a negative state, with a cumulative GMB of -9811.19 mm w.e. and an average annual GMB between -464.85 mm w.e. and -632.19 mm w.e. The vertical GMB increased by 244.83 w.e./100 m and 18.77 w.e./100 m in the ablation zone and the accumulation zone, respectively. From 2000 to 2002 and 2008 to 2010, the melting of glaciers slowed down, and the ablation was intensified from 2002 to 2008 and from 2010 to 2016. Strikingly, the loss of glaciers was most serious during the period 2005-2009. (3) The river runoff responded strongly to the change of GMB within the year, especially in July and August, namely, the GMB loss accounted for 75.4% of the total amount of the whole year, and the river runoff accounted for 55.1% of the annual total. The inter-annual glacial meltwater recharge rate fluctuated between 19% and 31%, which may be due to the differences of precipitation and snow melt water recharge rates in different years. The contribution rate of glacial meltwater of the MRB is close to that of other river basins on the northern slope of the Tianshan Mountains, which can further confirm the reliability of the GMB estimation results. Above all, the research can provide reference for the study of GMB in other river basins.

This article used the Weather Research and Forecasting Model (WRF) version 3.8 and simulated rainfall event in the period of July 21 to 22, 2012 in Beijing as a case study, with consideration of different land use and cover data. The rainfall event was simulated using a physical parametrization scheme that included a multi-layered city dome model. The results of the hourly and accumulative rainfall simulation indicated that the expansion of the urban area made the rainfall last longer and it also led to bigger affected area by the rainfall. Based on the simulated rainfall event, the duration of hourly rainfall of more than 16 mm increased by 1 h between 1990 test and 2010 test, and the area of accumulative precipitation exceeding 150 mm over 24 h increased by 1534 km ² over the same period. Further research is needed to determine the possible impact of changes in atmospheric aerosol particles produced by human activities in the urban area and the changes in landscape urbanization density on rainfall. Identifying the effect of landscape urbanization in metropolitan areas on rainfall will improve countermeasures for prevention of urban flooding and waterlogging risk. Future research will focus on improving the simulation effect of the model on the precipitation process. There was some discrepancy between the simulated and actual hourly precipitation in this study. Future work will investigate the parametric scheme of the model and the precipitation mechanisms it uses.

The spatial pattern changes of bays under the influence of reclamation can profoundly reflect how human activities affect the natural environments, which is important to effectively protect and utilize bay resources. Based on 6 Landsat TM/OLI remote sensing images during 1990-2015, this study analyzed the variations of major bays from the coastline and bay surface morphology and explored the correlation between the reclamation intensity and spatial pattern changes for the 12 major bays in the East China Sea (ECS). The main conclusions include that: (1) the length of the main bay coastline in the East China Sea, from 1990 to 2015, increased by 66.65 km. The extensive coastline growth was found during 2005-2010 and the growth reached 38 km. Sansha Bay has the longest coastline (439 km) and the shortest (105 km) was found in Luoyuan Bay; Xinghua Bay experienced the largest coastline growth (54.53 km) in the past decades, and the least was in Luoyuan Bay (25.75 km). In general, the artificial coastline continued to increase and the degree of artificialization had been continuously strengthened. (2) The coastline of the bay continuously moved to the sea, with a distance of 26.93 km (1.08 km/a). The most significant seaward expansions were found in 1995-2000 and 2005-2010, reaching 7.10 km and 6.00 km, respectively. Hangzhou (4.93 km) and Xinghua bays (4.15 km) experienced the largest seaward expansion of coastline, while Xiamen Bay had the shortest (0.55 km). (3) The total area of the major bay waters decreased from 13.85 km2 in 1990 to 12.29 km2 in 2015 in the East China Sea, down by 11.23%. Additionally, the morphological indices of the bays showed a continuous rise trend, which indicates that spatial patterns were transformed to be more complicated. The largest reduction with water area was observed in the Hangzhou Bay (0.726 km2), accounting for 46.69% of the research area. (4) The indexes of artificiality and development intensity showed a continuous rise trend. The utilization degree in the southern part of the study area is higher than that of the northern part, and the interannual fluctuation of the development intensity in the north is much varied. In addition, the bay development is positively correlated with the length of the coastline, the length of the artificial coastline and the shape index of the bay, and negatively correlated with the length of the natural coastline and the area of the waters. As the development intensity increased, the intensity of reclamation activities increased significantly.

The formation mechanism and influencing factors identification of soil erosion are the core and frontier issues of current research. However, studies on the multifactor synthesis are still insufficient. In this study, the simulation of soil erosion and its quantitative attribution analysis have been conducted in different morphological types of geomorphology in a typical karst basin based on the RUSLE model and the geographical detector method. The influencing factors, such as land use type, slope, rainfall, elevation, lithology and vegetation cover, have been taken into consideration. Results show that the strength of association between the six influencing factors and soil erosion was notably different in various morphological types of geomorphology. Land use type and slope were the dominant factors of soil erosion in the Sancha River Basin, especially for land use type whose power of determinant (q value) for soil erosion was much higher than that of other factors. The q value of slope declined with the increase of relief in mountainous areas, namely it was ranked as follows: middle elevation hill > small relief mountain > middle relief mountain. Multi-factor interactions were proven to significantly strengthen soil erosion, particularly for the combination of land use type with slope, which can explain 70% of soil erosion distribution. It can be found that soil erosion in the same land use type with different slopes (such as dry land with a slope of 5°and dry land with slopes above 25°) or in the diverse land use types with the same slopes (such as dry land with a slope of 5° and forest with a slope of 5°), varied greatly. This indicates that prohibiting steep slope cultivation and the Grain for Green Project are reasonable measures to harness soil erosion in karst areas. Based on statistics of soil erosion difference between diverse stratifications of each influencing factor, results of risk detector suggest that the amount of stratification combinations with significant difference accounted for 55% at least in small and middle relief mountains. Therefore, the spatial heterogeneity of soil erosion and its influencing factors in different morphological types of geomorphology should be investigated to control karst soil loss more effectively.

The presence of CO₂ in the caves affected by intense tourism activities has a significant impact on the drip hydrogeochemistry and sedimentation. In this investigation, a continuous monitoring on the indexes such as CO₂, temperature, relative humidity, tourist number and drip hydrochemistry was conducted in Guizhou Suiyang Dafeng Cave from 30 September 2017 to 9 October 2017. Following the collection of data, different methods were applied systematically to analyze a number of elements comprehensively. The observed results show that, under the influence of factors such as tourist number and ventilation effect of cave, the partial pressure of CO₂ in the cave (PCO_{2 (A)}) presented obvious diurnal and interdiurnal variations in the time sequence, and showed a higher value in daytime whereas a lower value at nighttime, and also a higher value on days with many tourists and a lower value on days with few tourists. In space variation, due to different ventilation degrees and cavity volumes, the PCO_2(A) of different monitoring points had obvious differences, from the deep cave to the entrance of cave as 3# (Magical Spring and Dewdrop) >1# (Time Tunnel)>2# (Legendary Luminous Pearl). Through the comparison of PCO_2(A) and drip temperature, the former had more significant influence on the solubility of CO₂ than the latter did. Moreover, the drip temperature and drip partial pressure of CO₂ (PCO_2(W)) of cave generally had the same trend of variation with that of PCO_2(A), and also presented obvious diurnal and interdiurnal variations. The pH, SIc, and HCO₃^- generally had a trend of variation in the opposite way to that of PCO_{2 (A)}, EC and Ca²⁺ had no obvious diurnal variation but certain interdiurnal variation. With an increase in the strength of tourism activities, the variation amplitude of drip hydrochemistry gradually increased. Furthermore, the differences in the factors such as cavity structure, size and closeness caused differences in the diffusion speed of PCO_2(A) and cave ventilation degree, and further influenced the hydrochemistry of the constituents of cave drip and sedimentation conditions of cave. Overall, this study will have a significant impact on the research on protection and management of cave environment as well as its karst cave carbon cycle.

The stream-power incision model shows that a bedrock channel longitudinal profile is characterized by a smooth, concave-up shape at the steady state, and its characteristics reflect the influences from external forces, such as tectonics, climate, and rock resistance. However, most of the natural rivers present a transient state characterized by knickpoints on longitudinal profiles, which can also infer the influences from external forces. Widespread knickpoints at high altitudes on river longitudinal profiles along the Zoulang Nan Shan (mountain), which is a part of northern Qilian Mountains, provide a particular case for studies on the factor affecting the disequilibrium profile. The analysis of the knickpoints indicates that the formation of the knickpoint at high altitudes is not influenced by lithology, climate and/or tectonics. By comparing the plaeo-glaicial evidences, we proposed that the high-altitude knickpoint reflects the boundary between residual glacier valleys and fluvial channels. The result suggests that we should pay more attention to the inheritance landform by ancient glaciation when analyzing the knickpoint located at high altitudes. This study would greatly increase the knowledge about the geomorphic evolution on high mountain ranges along orogenic belts.

At present, there is a lack of sufficient understanding of the evolution of floodplains and bars (FB) at the Jingjiang reach of Yangtze River after Three Gorges Reservoir impoundment. The erosion/accretion pattern and morphological evolution of FB at the Jingjiang reach were studied using remote sensing images acquired in low water periods before and after Gorges Reservoir impoundment. The results showed that the total area of FB at the Jingjiang reach shrank continually after the reservoir impoundment. By 2015 an area of 4.56 km² had been scoured away, and most of the scour occurred within the first 6 years after the impoundment at an erosion rate of 0.55 km²/a. There were evident differences in erosion/accretion pattern and in morphological evolution between the upper and lower sections of Jingjiang reach. The total area of FB at the upper Jingjiang has continually decreased due to scouring after the impoundment, and the scouring intensity was greater than that in the lower Jingjiang. In contrast, erosion of the lower Jingjiang took place in the early period after the impoundment (2002-2009), but accretion was observed in the later period (2009-2015). In erosion/accretion distribution, the floodplains of upper Jingjiang reach were continually scoured and shrunk while the bars at concave banks were scoured in the early period but were accreted slightly in the later period; the mid-channel bars of upper Jingjiang were accreted in the early period but were scoured in the later period. In contrast, erosion mainly occurred at the floodplains of lower Jingjiang, while the bars at its concave banks and mid-channel bars were accreted. The mid-channel bar evolution at the Jingjiang reach after the reservoir impoundment was classified into eight types according to their position movement and erosion/accretion dynamics. On morphological evolution, the protruding parts of floodplains and the bars at concave banks of the upper Jingjiang were visibly eroded, while the morphology changed little. At the lower Jingjiang, however, the floodplains evolution had a characteristic pattern that the upstream part was eroded back, with a shrinkage of the top, while the downstream part was accreted, resulting in the alteration of convex bank from a highly curved morphology to a flattening-curved morphology. This erosion-accretion process of floodplains at the upstream convex bank even extended to the adjacent downstream concave bank when there was no obvious straight section connecting the neighboring highly curved bends or when the upstream convex bank shared the same bank with the downstream concave bank. Extension of upstream floodplain accretion to the downstream concave bank was an important reason for the development of both the bars at concave banks and the mid-channel bars at the lower Jingjiang. Generally, the accretion at the concave bank did not span to the top of concave bank.

The Jinsha River has attracted considerable attention for nearly a century due to its unusual drainage basin morphology. Most models describing its evolution suggest that the modern Jinsha River, draining the Tibetan Plateau margin, was once a tributary to a single, southward river system called "Paleo-Red River", which drained into the South China Sea and then its flow direction changed to east to join the Yangtze River due to river capture. The Red River submarine fan, considered to have been primarily fed by the Paleo-Red River system, suddenly disappeared at 5.5 Ma provides an important chronological constraint on this reorganization of drainage lines and reversal event. However, no geomorphic evidence has been found to agree with this hypothesized timeframe. Here, we present electron spin resonance (ESR) ages from eight terraces preserved in the Jinjiangjie reach of the Jinsha River together with their GPS altimetry data. Their ages from old to young are 1.07 Ma, 0.70 Ma, 0.65 Ma, 0.51 Ma, 0.47 Ma, 0.44 Ma, 0.30 Ma and 0.18 Ma, with a calculated average river incision rate of 147 mm/ka since 1.0 Ma. The paleo-topography, reconstructed by filling the deeply incised river gorges with digital elevation model (DEM) data, shows that the upper reach of the Paleo-Red River was captured by the Yangtze River and changed its flow direction eastward at the time of disruption of the 2000 m asl paleo-topographic surface in the Jinsha River drainage basin. The age of the paleo-topographic surface formation would be approximately 5.5 Ma using the average river incision rate extrapolation, suggesting that the present Jinsha River system was born after 5.5 Ma. This data support the chronological constraint from the Red River submarine fan, and hypothesized evolution of the Jinsha River.

In the context of climate change and urbanization, increase of flood disasters has been a great challenge for Chinese cities and one of the hotspots in natural hazards research. This paper aims to develop a commonly used paradigm for urban flood emergency assessment at city scale. The city center (within outer ring) of Shanghai, China was selected as the study area because it exhibits enhanced consequences of flooding. A simplified hydrodynamic model (FloodMap) that tightly couples a 1D river flow model with a 2D floodplain flow model in urban environment, was used to predict 100-year and 1000-year flood inundation in the current state, the 2030s and the 2050s with relative sea level rise taken into account. Moreover, GIS-based network analysis (service area and closest facility) was employed to evaluate the transportation conditions and emergency responses accessibility of critical public service sectors (Medical Treatment) under normal conditions and multiple flood scenarios. The results show that the performance of the emergency medical services was largely dependent on flood magnitude (extent and depth), traffic conditions (travel speed) and emergency station positioning. In normal conditions, when no flood restrictions are in place, emergency medical services would be able to reach most parts of the study area within 15 minutes even under significant traffic congestion. As inundation would mainly occur within 2-3 km of Huangpu river banks, flood has a limited influence on emergency medical treatment for the entire region of central Shanghai. Even during 1000-year flood scenario in the 2050s, over half (51%) of the area is predicted to be accessible within 15 minutes. Floodwater may directly compromise a number of hospitals, leading to travel delays and obvious disruption of emergency services in riparian areas. This study suggests that the framework developed for coupling flood modeling with urban emergency response assessment, is proved to be effective and practical, and will provide a support to the decision making of urban flood emergency management.

The Tongtian section of the Yangtze River is located in ??the central part of the Tibetan Plateau where the neotectonic activity is illustrated by frequent earthquakes, such as the Yushu earthquake (Ms 7.1) on April 14, 2010. The study area is situated in the upstream parts of the Yellow River Basin, the Yalong River and Lanchang River catchments. In this region the tributaries have developed an inverted drainage pattern with nearly right-angle intersection. Based on terrain and areal river system analysis, including geomorphic index calculation, this paper discusses the evolution of the drainage pattern related to the neotectonic movements in this area. Two groups of valleys are distinguished with NW-SE and SW-NE directions, respectively. The NW-trending rivers are unfit channels with gentle slope and large width, while most of the SW-trending rivers are canyons with steep slope and V-shaped transect. It turns out that the steepness index (k_s) in the southeastern part of the Tongtian River is higher than that in the Duocai-Ningqia basin, Dengailong basin, Yequ basin and the southwestern part of the Batang basin. The stream length-gradient index (SL) is similar in the whole catchment, but the SL values in the inverted channels and nearly right-angle intersecting channels are abnormal. The value of the hypsometric integral (HI) is over 0.45 at both sides of the Tongtian River, while it is 0.15-0.45 in the Duocai-Ningqia basin, Dengailong basin, Yequ basin and Batang basin. The values and distribution of geomorphic indexes indicate that the pre-existing SE-trending parallel-drainage pattern turned to an inverted-drainage pattern as a result of strike-slip faulting. Dangjiang, Lixing, Longbao and the northeastern part of the Shanglaxiu regions became pull-apart basins, while the tributaries of the Tongtian River in the northeast eroded dramatically headward as a result of the uplift of the NE-trending thrust, and finally captured the former SE-trending channels.

The anastomosing river located at the First Great Bend of the Yellow River is different from other sand-bedded anastomosing rivers because of its gravel-bedded materials. So, it needs to be revealed whether its specific characteristics have a similarity with the sand-bedded anastomosing river, in terms of erosion and deposition, the stability of channel and interchannel wetlands, and so on. Based on four remote sensing images in 1990, 2001, 2013, and 2016 and two Google earth images in 2011 and 2013, combined with field sampling and observations, the Qihama anastomosing river reach with a main channel length of about 12 km was selected to analyze the variations of channel planforms and sedimentary characteristics in the period 1990-2016. The results show that the gravel-bedded anastomosing river has a high stability as a whole, and there is no obvious bank erosion and deposition for varied channels and wetlands. During the past 26 years, the anastomosing belt area increased by 2.43%, and the ratio of land to water area was close to 1:1. The number of wetlands increased gradually with the highest increasing rate of 62.16% due to the fragmentization of some small interchannel wetlands. Talweg migrated to the left or the right alternately in a long period of time, and the migration rate was relatively stable. Due to the influence of talweg migration, the change of islands in the main channel is large and the bank shift rate of the main channel was about 5 m/a. The network composed of secondary channels is very stable and the channel average migration rate was only about 1 m/a. The sediments in the bank columnar sections are mainly composed of fine sands or silts, and the clay content is relatively high. Besides, the grain-size distribution presents a multi-peak curve, which is little different from the muddy sediments in bank columnar sections of sand-bedded anastomosing rivers. However, the dense vegetation on the riparian and interchannel wetlands protects the anastomosing channels in the study river reach from being eroded, and maintains the stability of the channels, which is also an important factor contributing to high stability of the gravel-bedded anastomosing river system.

This study examines spatial and temporal changes in the continental coastline and the intertidal zone from the Xiuzhen estuary to the Lianxing estuary in Jiangsu province from 1984 to 2016. This work employed an improved water-line method based on 61 multi-source remote-sensing images, as well as tide and measured slope data. The coastline is a combination of the mean high-tide line and artificial coastline. The mean high-tide line was derived from elevation data contained in the waterlines through the improved water-line method. Water lines were extracted from remote sensing images using object-oriented classification, band operation, etc. Then, tides at the tide stations at image acquisition times were predicted using the T-Tide program. The predicted tides were assigned to water lines and intertidal slopes were calculated. Finally, mean high-tide and low-tide lines were determined from measured and calculated slopes. The quantitative analysis of the coastline, mean low tide line, and intertidal zone yielded the following main conclusions. From 1984 to 2016, Jiangsu's coastline advanced mainly towards the sea because of coastal development. The natural shoreline decreased from 458.24 to 166.74 km, while the artificial shoreline increased from 163.66 to 598.74 km. The length of Jiangsu’s continental coastline also increased from 621.90 to 765.48 km. During this period, the positions and lengths of different segments of the coastline changed. The deposited coast, which advanced toward the sea at an annual rate of 83.03 m, was 127.62 km long. The reclaimed coast, which advanced towards the sea at an annual rate of 87.63 m, was 401.21 km. The erosional coast, which receded at an annual rate of 10. 81 m, was 71.17 km long. The eroded reclaimed coast, which receded at an annual rate of 8.64 m, was 25.95 km long. The area of Jiangsu underwent a net increase of 104332 hm², primarily due to reclamation, with reclaimed land representing 98520 hm². Erosion mainly occurred in the abandoned Yellow River Delta, but during 2008-2016, it extended southward from the Xinyang to the Doulong harbor. The slopes of the intertidal zone became steeper due to reclamation and shoreline erosion, changing from 1.4‰ to 1.9‰. The abandoned Yellow River Delta experienced the most severe change in slope, with its mean slope in the range of 3‰-14‰. The mean slope of the radial sandbank of the onshore coast, which had the gentlest slope, increased from 0.9‰ to 1.5‰. The intertidal area decreased by 38% from 271747 to 168645 km², while the mean width of the intertidal zone decreased by 39% from 5064 m to 3096 m.

Hydrological and biogeochemical cycles process in a watershed ecosystem are closely coupled by the physical function of the hydrological flux, of which the coupling process of the matter and energy in the spatial and temporal scales will provide important basis for matter balance in biogeochemical cycles. These cycles also influence ecosystem productivity and exchanges with the atmosphere and the downstream water bodies. Therefore, the research on biogeochemical cycle and hydrological coupling process in the watershed scale will reveal the coupling mechanism on the carbon-nitrogen coupling cycles between terrestrial and aquatic ecosystem under water cycle driving, and the interaction of human activities and associated biological, physical and chemical processes under climatic change. The aims of this study are to synthetically clarify the biogeochemical and hydrological coupling characteristics in temporal, spatial and spatio-temporal scales within a watershed ecosystem, reveal the coupling of nutrient cycling in spatio-temporal scales within a continuum of atmosphere-land-rivers-estuaries-marine systems, which are connected by water, gas and aerosol fluxes; disclose the biological regulation mechanism of the biogeochemical and hydrological coupling processes by the change of ecological stoichiometry characteristics within the watershed and the regulation of nutrient input and output by water-land interaction zone, and then finally enhance our understanding of ecohydrological and biogeochemical process and its ecological dynamics at watershed landscape scale.

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.

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.

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.