大汶河流域中上游地区岩溶地下水水化学特征及其控制因素分析

为查明大汶河流域中上游地区岩溶地下水水化学特征和离子来源,基于2018年枯、丰两期采集的岩溶地下水样品水化学数据,综合运用数理统计、相关性分析、Piper图、Gibbs图以及离子比值等方法,对大汶河流域中上游地区岩溶地下水水化学特征及其控制因素进行了分析。结果表明,大汶河流域中上游地区枯、丰水期岩溶地下水的pH均值分别为7.6和7.5,整体表现为弱碱性。岩溶地下水中Ca²⁺为占优势的阳离子,HCO^-₃和SO^2-₄为主要阴离子。枯、丰期岩溶地下水中ρ(TDS)均值分别为645.4,648.4 mg/L。按照TDS划分,大汶河流域中上游地区岩溶地下水均属于淡水或微咸水;枯、丰水期岩溶地下水水化学类型均以HCO₃·SO₄-Ca为主。岩石风化作用是控制区内岩溶地下水水化学特征的主要控制因素,碳酸盐岩和硅酸盐岩矿物的溶解是地下水主要离子的重要来源。同时,大汶河流域中上游地区岩溶地下水还受到了比较明显的人为输入影响,地下水中NO^-     

CHEMICAL WEATHERING PROCESSES AND ATMOSPHERIC CO2 CONSUMPTION OF HUANGHE RIVER AND CHANGJIANG RIVER BASINS

Rock weathering plays an important role in studying the long-term carbon cycles and global climatic change. According to the statistics analysis, the Huanghe (Yellow) River water chemistry was mainly controlled by evaporite and carbonate weathering, which were responsible for over 90% of total dissolved ions. As compared with the Huanghe River basin, dissolved load of the Changjiang (Yangtze) River was mainly originated from the carbonate dissolution. The chemical weathering rates were estimated to be 39.29t/(km²·a) and 61.58t/(km²·a) by deducting the HCO ₃ ⁻ derived from atmosphere in the Huanghe River and Changjiang River watersheds, respectively. The CO₂ consumption rates by rock weathering were calculated to be 120.84×10³mol/km² and 452.46×10³mol/km²annually in the two basins, respectively. The total CO₂ consumption of the two basins amounted to 918.51×10⁹mol/a, accounting for 3.83% of the world gross. In contrast to other world watersheds, the stronger evaporite reaction and infirm silicate weathering can explain such feature that CO₂ consumption rates were lower than a global average, suggesting that the sequential weathering may be go on in the two Chinese drainage basins. Foundation item: Under the auspices of Ministry of Science and Technology Project of China (No. G1999043075) Biography: LI Jing-ying (1974-), female, a native of Xinye of Henan Province, Ph.D., associate professor, specialized in environmental geochemistry. E-mail: wxxljy2001@public.qd.sd.cn     

Water discharge variability of Changjiang （Yangtze） and Huanghe （Yellow） Rivers and its response to climatic changes

Influences of large-scale climatic phenomena, such as the E1Nifio/La Nifia-Southem Oscillation （ENSO） and the Pacific Decadal Oscillation （PDO）, on the temporal variations of the annual water discharge at the Lijin station in the Huanghe （Yellow） River and at the Datong station in the Changjiang （Yangtze） River were examined. Using the empirical mode decomposition-maximum entropy spectral analysis （EMD- MESA） method, the 2- to 3-year, 8- to 14-year, and 23-year cyclical variations of the annual water discharge at the two stations were discovered. Based on the analysis results, the hydrological time series on the inter- annual to interdecadal scales were constructed. The results indicate that from 1950 to 2011, a significant downward trend occurred in the natural annual water discharge in Huanghe River. However, the changes in water discharge in Changjiang River basin exhibited a slightly upward trend. It indicated that the changes in the river discharge in the Huanghe basin were driven primarily by precipitation. Other factors, such as the precipitation over the Changjiang River tributaries, ice melt and evaporation contributed much more to the increase in the Changjiang River basin. Especially, the impacts of the inter-annual and inter-decadal climate oscillations such as ENSO and PDO could change the long-term patterns of precipitation over the basins of the two major rivers. Generally, low amounts of basin-wide precipitation on interannual to interdecadal scales over the two rivers corresponded to most of the warm ENSO events and the warm phases of the PDO, and vice versa. The positive phases of the PDO and ENSO could lead to reduced precipitation and consequently affect the long-term scale water discharges at the two rivers.     

Snow cover variation and streamflow simulation in a snow-fed river basin of the Northwest Himalaya

Snowmelt is an important component of any snow-fed river system.The Jhelum River is one such transnational mountain river flowing through India and Pakistan.The basin is minimally glacierized and its discharge is largely governed by seasonal snow cover and snowmelt.Therefore,accurate estimation of seasonal snow cover dynamics and snowmeltinduced runoff is important for sustainable water resource management in the region.The present study looks into spatio-temporal variations of snow cover for past decade and stream flow simulation in the Jhelum River basin.Snow cover extent(SCE) was estimated using MODIS(Moderate Resolution Imaging Spectrometer) sensor imageries.Normalized Difference Snow Index(NDSI) algorithm was used to generate multi-temporal time series snow cover maps.The results indicate large variation in snow cover distribution pattern and decreasing trend in different sub-basins of the Jhelum River.The relationship between SCE-temperature,SCE-discharge and discharge-precipitation was analyzed for different seasons and shows strong correlation.For streamflow simulation of the entire Jhelum basin Snow melt Runoff Model(SRM) used.A good correlation was observed between simulated stream flow and in-situ discharge.The monthly discharge contribution from different sub-basins to the total discharge of the Jhelum River was estimated using a modified version of runoff model based on temperature-index approach developed for small watersheds.Stream power - an indicator of the erosive capability of streams was also calculated for different sub-basins.     

Assessing land use/land cover change impacts on the hydrology of Nyong River Basin,Cameroon

Uncontrolled land use land cover change(LULCC) is impacting watershed hydrology,particularly in tropical watersheds in developing countries. We assessed the extent of LULCC in the southern portion of the Nyong River basin through analysis of three land use maps in 1987, 2000 and2014. LULCC impact on hydrological variables of the Mbalmayo, Olama, Pont So'o, Messam, and Nsimi sub-watersheds of the southern portion of the Nyong River basin were evaluated by using the linear regression modeling and the Mann-Kendall test. This study reveals that dense forest cover decreased by16%, young secondary forest increased by 18%,agricultural/cropland increased by 10%, and built-up area/bare soil increased by 3% from 1987 to 2014.The decrease in dense forest cover at 0.6% per year on average was driven by indiscriminate expansion of subsistence agricultural/cropland through shifting and fallow cultivation farming systems. Nonsignificant trends in total discharge, high flows, and low flows were observed in the large sub-watersheds of Mbalmayo and Olama from 1998 to 2013 with LULCC within the watershed. In contrast, significant decreasing trends in stream discharge(up to-5.1%and-5.9%), and significant increasing trends in high flows(up to 2.1% and 6.3%), respectively, were observed in the small sub-watersheds of Pont So'o and Messam from 1998 to 2013, particularly with increase in agricultural/cropland cover and decrease in dense forest cover. However, we found nonsignificant trends in mean annual discharge and low flows for all and whole watershed with LULCC. The results reveal spatially varying trends of stream discharge, low flows and high flows among the subwatersheds with LULCC within the study watershed.The results suggest that the impacts of LULCC on watershed hydrology are easily detected in small subwatersheds than in large sub-watersheds. Therefore,the magnitude of dense forest cover loss must be significantly greater than 16% to cause significant changes and common trends in the hydrology of the sub-watersheds of the southern portion of the Nyong River basin. The Mann-Kendall and Regression approaches show appreciable potential for modelling the impacts of LULCC on the hydrology of the southern portion of the Nyong River basin and for informing forest management.     

Variations of dissolved iron in the Amur River during an extreme flood event in 2013

As a key factor limiting primary productivity in marine ecosystem, dissolved iron(DFe) export from fluvial systems has increased recently. There is particular concern about discharges of DFe during extreme flooding, when they are thought to increase considerably. An extreme flood event that caused inundation of extensive areas of Far Eastern Russia and Northeastern China occurred in the basin of the Amur River during summer and autumn 2013. During this event, water samples were collected in the middle reaches of the Amur River and the lower reaches at Khabarovsk City and analyzed for DFe concentrations and other aquatic parameters. The results show that the average DFe concentrations in the middle reaches of the Amur River(right bank) and at Khabarovsk were 1.11 mg/L and 0.32 mg/L, respectively, during the extreme flood in 2013. The total discharge of DFe during the flood event was 6.25 × 104 t. The high discharge of DFe during the flood reflects the elevated discharge of the river, hydrologically connected riparian wetlands, vast quantities of terrestrial runoff, and flood discharges from the Zeya and Bureya reservoirs. These results show that long-term monitoring is needed to identify and assess the impacts of DFe transport on the downstream reaches, estuarine area, and coastal ecosystems of the Amur River.     

Distributions of Picophytoplankton and Phytoplankton Pigments Along a Salinity Gradient in the Changjiang River Estuary,China

We investigated the abundance of different picophytoplankton groups and the phytoplankton pigment ratio in relation to environmental factors such as nutrients and suspended solids along a salinity gradient in the Changjiang River Estuary.The average numbers of Synechococcus spp.（Syn） and picoeukaryotes （Euk） were （2.7 ±5.1）×l03 and （1.1±1.4）×l03 cells mL-1,respectively.Prochlorococcus spp.（Pro） was only found in the high-salinity brackish water with the concentration of 3.0× 10^3 cells mL-1.Syn and Euk numbers both tended to increase offshore and Syn showed a larger variation in cell abundance than Euk.The contribution of picophytoplankton to total phytoplankton biomass increased with increasing salinity and decreasing nutrient concentrations from the estuary to the open ocean.The response of different picophytoplankton groups to environmental variables was different.Water temperature was more important in its control over Euk than over Syn,while nutrients were more important in their influence over Syn than over Euk.Phytoplankton pigment ratios were different in the three different ecological zones along the salinity gradient （i.e.,freshwater zone with 0-5 range,fresh and saline water mixing zone with 5-20 range,and high-salinity brackish water zone with 20-32 range）,where three different phytoplankton communities were discovered,suggesting that phytoplankton pigment ratios can be considered as a complementary indicator of phytoplankton community structure in the Changjiang River Estuary.     

Catchment-based imperviousness metrics impacts on floods in Niushou River basin,Nanjing City,East China

Concerns regarding urbanization impacts on floods gradually moved from end-of-pipe solutions, based on open channel hydraulics improvement, to imperviousness ratio limiting and then to land use control and to integrated planning at local and large scale levels. The Niushou River basin is one of the fastest urbanizing areas in Nanjing City, East China, however, the high urban land percentage has leaded to series of flooding events. The paper aims to reveal the impact of imperviousness ratio, patterns and drainage system on flooding areas based on the unit of catchment and Storm Water Management Model (SWMM). The following conclusions were reached. 1) The ratio or spatial characteristics of the impervious surface affected the runoff volumes and associated floods areas. Despite the well-established drainage system, the high imperviousness ratio, particularly clustered pattern in locations such as hydrological sensitive zones aggravated the flooding tension across the basin. 2) The poor drainage hydraulic efficiency in local areas, and the lack of integral processes of infiltration, yield, storage and discharge in local catchment and larger basin are also significant factors. 3) The Niushou River basin development should improve the drainage transformations from a single local, short-term drainage process into integral, elastic processes of infiltration, yield, storage, and discharge.     

A 2011 drought event affecting distribution of nutrients and chlorophyll in the Zhujiang River estuary

During the summer of 2011,a severe drought event occurred throughout the Zhujiang(Pearl)River Basin of South China.This decreased runoff into the river,resulting in increased salinity and reduced suspended substance.To examine the effects of this extreme drought on the distribution of nutrients and chlorophyll,we compared two surveys from 2006 and 2011.Results show that dissolved inorganic nitrogen concentration did not change from 2006 to 2011,whereas the proportions of NO 2 – and NH 4 + to DIN in 2011 increased.PO 4 3-concentration was lower in 2011 than in 2006,whereas there was no difference in SiO 3 2-concentration between these years.Correlation coeffi cients of salinity with levels of NO 3 –,NO 2 –,NH 4 +,PO 4 3-and SiO 3 2-in 2011 were all much higher than those in 2006,suggesting greater conservation of dissolved nutrients during the extreme drought event.Furthermore,calculated amounts of regenerated nitrate and phosphorus and their proportions to observed nutrients in 2011 were much lower than in 2006,indicating that nutrient regeneration decreased during the extreme drought period.Mean concentration of chlorophyll a(Chl-a)was considerably higher in 2011 than in 2006,and a harmful algal bloom of Cochlodinium geminatum was observed in the estuary,owing to water stagnancy and lower turbidity as a consequence of drought.Therefore,the extreme drought event in 2011 changed the composition ratio of nutrients,enhanced nutrient conservative behavior,and reduced nutrient regeneration.This affected some key ecological processes in the estuary.     

喀斯特地区不同岩土组构对岩溶碳通量的影响

我国南方喀斯特地区岩石裸露率高、土层浅薄且分布不均,这种特殊的岩土组构如何影响水文过程对于准确估算岩溶碳通量具有重要意义。水化学径流法是计算流域尺度岩溶碳通量的常用方法,其中流域面积和流量作为2个重要参数在喀斯特地区往往难以准确获取。在普定喀斯特生态系统观测研究站设计了一组岩土比(1:1和4:1)和一组土层厚度(5,20,100 cm)共计5种岩土组构的模拟试验场。通过一个完整水文年的流量和水化学监测,定量研究了岩石裸露率和土层厚度对水文过程以及岩溶碳通量的影响。研究结果表明,5个模拟试验场岩溶碳通量平均值为(17±3) gC/m2/a,受渗漏量控制,雨季(5-10月)约占95%;岩石裸露率(2组岩土组构之间)对渗漏量的影响可达14%,且随着岩石裸露率增加,入渗系数也相应增加;土层厚度对渗漏量的影响仅在1%~2%之间。此外,对8个野外流域观测数据的分析发现,入渗系数与岩溶碳通量的相关性最为显著,说明入渗系数是喀斯特地区不同岩土组构地质背景影响和控制岩溶碳通量的主要因素,同时这种影响可能随降雨量变化而变化,即入渗系数并非常数。      

涟源富硒土壤研究与湖南省富硒土壤分布初探

在部省合作"湖南省娄邵盆地多目标地球化学调查"项目的资助下,系统地采集测试了涟源市耕地和园地的表层土壤样品。调查发现该地区发育了大量的富硒土壤,富硒土壤的来源主要与震旦系上统—寒武系下统和二叠系中上统的黑色岩系有关。上述黑色岩系分布区域的表层土壤具有全区最高的硒含量,均大于1 mg/kg,部分甚至达到硒过量的水平。经文献研究和综合评价,推断黑色岩系风化物质扩散堆积形成的山间盆地是湖南省快速高效的寻找富硒土壤的理想靶区。     

Seasonal Changes in Phytoplankton Biomass and Dominant Species in the Changjiang River Estuary and Adjacent Seas：General Trends Based on Field Survey Data 1959-2009

The characteristics of seasonal variation in phytoplankton biomass and dominant species in the Changjiang River Estuary and adjacent seas were discussed based on field investigation data from 1959 to 2009. The field data from 1981 to 2004 showed that the Chlorophyll-a concentration in surface seawater was between 0.4 and 8.5 ktg dm-3. The seasonal changes generally presented a bimodal trend, with the biomass peaks occurring in May and August, and Chlorophyll-a concentration was the lowest in winter. Seasonal biomass changes were mainly controlled by temperature and nutrient levels. From the end of autumn to the next early spring, phytoplankton biomass was mainly influenced by temperature, and in other seasons, nutrient level （including the nutrient supply from the terrestrial runoffs） was the major influence factor. Field investigation data from 1959 to 2009 demonstrated that dia- toms were the main phytoplankton in this area, and Skeletonerna costatum, Pseudo-nitzschia pungens, Coscinodiscus oculus-iridis, Thalassinoema nitzschioides, Paralia sulcata, Chaetoceros lorenzianus, Chaetoceros curvisetus, and Prorocentrum donghaiense Lu were common dominant species. The seasonal variations in major dominant phytoplankton species presented the following trends： 1） Skeletonema （mainly S. costatum） was dominant throughout the year; and 2） seasonal succession trends were Coscinodiscus （spring） →Chaetoceros （summer and autumn） → Coscinodiscus （winter）. The annual dominance of S. costatum was attributed to its environmental eurytopicity and long standing time in surface waters. The seasonal succession of Coscinodiscus and Chaetoceros was associated with the seasonal variation in water stability and nutrient level in this area. On the other hand, long-term field data also indicated obvious interannual variation of phytoplankton biomass and community structure in the Changjiang River Estuary and adjacent seas： average annual phytoplankton biomass and dinoflagellate proportion both presented inc     

Diurnal and seasonal variation of glacier meltwater hydrochemistry in Qiyi glacierized catchment in Qilian Mountains,Northwest China: implication for chemical weathering

In glacierized catchments, glacier runoff typically shows a strong diurnal cycle in the ablation season (June-September). To elucidate the effect of these processes on the chemical weathering, fresh snowfall and water samples were collected and studied from the supraglacial river, proglacial river, and gauging site in Qiyi glacierized catchment Qilian Mountains, Northwestern China, in the summer of 2011. The pH and electronic conductivity (EC) were determined in the field, and the concentrations of major ions (Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl^-, SO₄^2-, NO₃^-) were measured. The results indicated that EC linearly increased with increasing distance from the glacial snout, and the concentrations of major ions increased with increasing water-rock interaction time. Along the flow path of the glacier runoff, Na⁺ and Cl^- are more concentrated than other ions in the supraglacial river while Mg²⁺ and SO₄^2- are more concentrated than other ions at the gauging site. The discharge, pH, EC, and the concentrations of major ions exhibited significant diurnal variation along the flow path. On the other hand, the amplitude of variation diminished from upstream to downstream along the flow path. The chemical weathering rate (Na⁺+K⁺+Mg²⁺+Ca²⁺) was determined to be 10.9 t/yr/km². Moreover, further research indicated that the sampling method influenced the assessment of chemical weathering rates. When the sample was collected randomly in one diurnal cycle of hydrography, the estimated ionic flux could deviate -47%~73% based on estimated hourly data. In contrast, if three samples were collected at peak, base flow and the discharge decreasing rate starts to slow down in one diurnal cycle of hydrography, respectively, the deviation would be less than 15%. The smaller the diurnal variation of discharge, the smaller deviation calculated.     

鄂尔多斯盆地后期改造与砂岩型铀成矿关系

依据鄂尔多斯盆地中新生代地层接触关系、沉积建造、构造变形、主要构造变动事件及同位素测年等资料,对盆地后期改造期次、类型及分布进行了分析。盆地改造作用发生于晚侏罗世以来,可分为晚侏罗世、早白垩世、早白垩世末—古新世、始新世—中新世及中新世末—现今5个阶段,改造形式包括抬升剥蚀、冲断褶皱、叠合埋藏、断陷分隔及热力改造等,并且在空间上有明显的不均一性。盆地后期改造与砂岩型铀成矿的关系密切。提出了晚侏罗世以来多期抬升剥蚀期控制着砂岩型铀成矿作用的发生形成,构造抬升(掀斜)区控制着铀矿的空间展布,而冲断褶皱、叠合埋藏、断陷分隔等改造作用使含矿层变形破坏、深埋或与地下水补给区分割,对铀成矿作用不利。     

江汉平原地下水化学特征及水流系统分析

江汉平原水质性缺水问题日益突出,识别江汉平原地下水流系统分布模式,对地下水资源的合理利用与保护具有重要意义.选取江汉平原典型区域,综合水文地质条件、水动力场及水化学同位素指标深入分析地下水补给过程、水岩作用及滞留时间.得出由于碳酸盐岩的溶解,研究区的地下水化学类型属于HCO3-Ca (Mg)型.地下水中典型离子随深度增加逐渐降低,同位素随深度增加逐渐偏负,表现出地下水流系统呈局部与区域水流系统的特点,系统深度界限在10~20m.独立而复杂的局部水流系统在平枯水期地下水向河渠地表水排泄.根据3H的含量,局部水流为现代水,水循环交替迅速.受地形控制,中深层地下水总体由西和西北向东和东南径流,汇入汉江和长江,为区域水流系统.由于补给源的高程效应,区域水流的18O值存在明显分区,指示不同的补给来源与水流路径.山前丘陵区基本为现代水,向平原腹地纵深至汉江和长江排泄区,地下水年龄在几百年至6000a不等,水循环交替缓慢.研究发现江汉平原低洼排泄区存在区域水流的顶托补给,可为原生劣质水的分布与聚集研究提供依据.     

Formation and evolution of Emeishan basalt saprolite in vadose zones of Touzhai landslide source rockmass

In order to explain the formation process of slope hazards, and to identify the key factors leading to instability of a slope, Emeishan basalt saprolite in vadose zones of the Touzhai landslide in Zhaotong, Yunnan, was studied. The formation and evolution of Emeishan basalt saprolite was examined using, amongst other techniques, field investigations, thin section analysis, scanning electron microscopy (SEM) observations, chemical analysis, physical and water-physical property tests of rock masses. Field observations revealed that the majority of the weathered rock blocks were presented as a concentric layer structure in which an internal corestone was enveloped with several layers of external saprolized crust. Chemical and mineralogical analysis identified that iron was the most sensitive element and that the weathering progress usually started with the oxidation of Fe²⁺ to Fe³⁺ in rock blocks. Alkaline elements such as Si, Ca, Mg, Na and K were also dissolved and Fe and Al were concentrated in saprolized crusts. Results indicated that loss on ignition (LOI) also increased significantly. SEM results showed that the weathering intensity of the basalt blocks decreased gradually from the outside to the inside, and the mineral morphology significantly differed on both sides of the weathering front. The saprolized crusts presented cellular microstructure features due to the generation of micropore and clay minerals. Thin section analysis showed that plagioclase was relatively more stable than pyroxene and chlorite during weathering. With a centripetal propagation of the weathering front, saprolized crusts became thicker and corestones became smaller; fresh Emeishan basalt blocks gradually turned into saprolized blocks. Due to the loose structure and low strength of saprolite, the quality of the Emeishan basalt mass significantly deteriorated, this being a potentially important factor which caused the Touzhai landslide to occur.     

Evaluating Functions of Reservoirs′ Storage Capacities and Locations on Daily Peak Attenuation for Ganjiang River Basin Using Xinanjiang Model

Flooding is the most prevalent and costly natural disaster in the world and building reservoirs is one of the major structural measures for flood control and management. In this paper, a framework was proposed to evaluate functions of reservoirs′ locations and magnitudes on daily peak flow attenuation for a large basin of China, namely Ganjiang River Basin. In this study, the Xinanjiang model was adopted to simulate inflows of the reservoirs and flood hydrographs of all sub-catchments of the basin, and simple reservoir operation rules were established for calculating outflows of the reservoirs. Four reservoirs scenarios were established to analyze reservoirs′ locations on daily peak flow attenuation. The results showed that: 1) reservoirs attenuated the peak discharges for all simulated floods, when the flood storage capacities increase as new reservoirs were built, the peak discharge attenuation by reservoirs showed an increasing tendency both in absolute and relative measures; 2) reservoirs attenuated more peak discharge relatively for small floods than for large ones; 3) reservoirs reduced the peak discharge more efficiently for the floods with single peak or multi peaks with main peak occurred first; and 4) effect of upstream reservoirs on peak attenuation decreased from upper reaches to lower reaches; upstream and midstream reservoirs played important roles in decreasing peak discharge both at middle and lower reaches, and downstream reservoirs had less effect on large peak discharge attenuation at outlet of the basin. The proposed framework of evaluating functions of multiple reservoirs′ storage capacities and locations on peak attenuation is valuable for flood control planning and management at basin scale.     

Frozen ground and periglacial processes relationship in temperate high mountains: a case study at Monte Perdido-Tucarroya area(The Pyrenees,Spain)

Seasonally frozen ground,mountain permafrost and cryogenic geomorphological processes are important components of the Pyrenean high mountains.This work presents the results of a study on the distribution of frozen ground in a marginal and paraglacial environment of temperate mountains.An inventory was made of landforms and indicators of frozen ground,and frozen ground was mapped accordingly.During 2014 and 2016 ground temperatures and thermal regimes were monitored,basal temperatures of snow-cover(BTS)were measured and a thermal map was drawn.Differential thermal behaviours were detected among different elevations and slope orientations.Periglacial processes are the most widespread,in which frost weathering and nivation,together with gelifluction and cryoturbation,are the most efficient processes;the latter two are generally linked to the presence of frozen ground.The fall in air and ground temperatures with altitude,slope orientations,and snowpack thickness and evolution determine ground thermal regimes.In the study area,three types of thermal regimes were established:climate-controlled,snowcover-controlled,and frozen ground-controlled.Seasonally frozen ground occurs across a broad range of elevation between 2650 and 3075 m asl,whereas possible permafrost only occurs above 2750 m asl.     

山东黄河流域国土空间生态修复布局与路径

本文在分析山东黄河流域生态基础条件、生态本底状况,识别流域主要生态问题的基础上,提出了流域生态修复基本思路,构建了“两屏两心多廊”的流域生态修复格局,进行了流域生态修复分区;提出了流域生态修复的具体路径,主要是泰山和徂徕山-莲花山区域、黄河和大汶河生态廊道、黄河三角洲和东平湖湿地的生态修复;为实现流域一体化保护修复,从法律、经济、技术等方面构建了流域生态修复协同推进机制。     

Impacts of Land-use and Land-cover Changes on River Runoff in Yellow River Basin for Period of 1956–2012

River runoff is affected by many factors, including long-term effects such as climate change that alter rainfall-runoff relationships, and short-term effects related to human intervention(e.g., dam construction, land-use and land-cover change(LUCC)). Discharge from the Yellow River system has been modified in numerous ways over the past century, not only as a result of increased demands for water from agriculture and industry, but also due to hydrological disturbance from LUCC, climate change and the construction of dams. The combined effect of these disturbances may have led to water shortages. Considering that there has been little change in long-term precipitation, dramatic decreases in water discharge may be attributed mainly to human activities, such as water usage, water transportation and dam construction. LUCC may also affect water availability, but the relative contribution of LUCC to changing discharge is unclear. In this study, the impact of LUCC on natural discharge(not including anthropogenic usage) is quantified using an attribution approach based on satellite land cover and discharge data. A retention parameter is used to relate LUCC to changes in discharge. We find that LUCC is the primary factor, and more dominant than climate change, in driving the reduction in discharge during 1956–2012, especially from the mid-1980 s to the end-1990 s. The ratio of each land class to total basin area changed significantly over the study period. Forestland and cropland increased by about 0.58% and 1.41%, respectively, and unused land decreased by 1.16%. Together, these variations resulted in changes in the retention parameter, and runoff generation showed a significant decrease after the mid-1980 s. Our findings highlight the importance of LUCC to runoff generation at the basin scale, and improve our understanding of the influence of LUCC on basin-scale hydrology.