黄河巴彦高勒到头道拐河段冲淤演变的驱动因子分析（英文）

The Inner Mongolia reaches of the Yellow River face problems of severe sedimentation caused by a variety of complex factors. The sedimentation process in those reaches has been characterized using the sediment balance method, and the key factors affecting the process have been analyzed using the correlation analysis method. The results show that during the period 1952–2012 the Bayangaole(Bayan Gol) to Toudaoguai reaches in Inner Mongolia have undergone successive processes of accumulative sedimentation, then relative balance, and then accumulative sedimentation once again. The total annual sedimentation is 12.0341×10~8 m~3, of which accumulations from July to October account for 95.1% and the reaches from Sanhuhekou to Toudaoguai account for 98.5%. The main factor affecting scouring and sedimentation of the Bayangaole to Sanhuhekou reaches is the combined water and sediment condition. The critical conditions for equilibrium are an incoming sediment coefficient 0.007 kg·s·m~(–6) and a flow discharge 700 m~3·s~(–1). The main factor affecting scouring and sedimentation of the Sanhuhekou to Toudaoguai reaches is the incoming sediment from the tributaries on the south bank and the combined water and sediment condition of the main stream. The critical conditions of the main stream for maintaining equilibrium status are a flow discharge of the main stream exceeding 800 m~3·s~(–1) and a comprehensive incoming sediment coefficient 0.005 kg·s·m~(–6). The incoming sediment from the tributaries has little impact on the main stream when the annual sediment load is less than 0.1×10~8 t. The incoming sediment coefficient of the main stream and the incoming sediment from the tributaries both play vital roles in the riverbed evolution of the Inner Mongolia reaches, but the latter contributes the most.     

中国山区农村土地利用转型及其对土地整治的政策启示（英文）

The cultivation of mountainous land results in water loss and soil erosion. With rapid urbanization and industrialization in China, labor emigration relieves the cultivation of mountainous areas in regions with high poverty and leads to a significant land use transition. This research built an analysis framework for "land use transition – driving mechanism – effects –responses" for mountainous areas of China undergoing land use transition and then proposed the direction of mountainous land consolidation. The results showed that the turning point of land use morphology was the core of rural land use transition in mountainous areas. The expansion of cropland and the contraction of forestland have transitioned to the abandonment of cropland and the expansion of forestland; this transition was the main characteristic of the dominant land use change. Land marginalization and land ecological functional recovery were the main characteristics of the recessive land use transition in mountainous areas. Socioeconomic factors were the primary driving forces during land use transition in mountainous areas, with labor emigration being the most direct force. The rising costs of farming and the challenging living conditions causing labor emigration were fundamental driving forces. Rural land use transition in mountainous areas reduced the vulnerability of the ecological function of land ecosystems. The advantages and disadvantages of the socioeconomic effects should focus on rural development of mountainous areas as well as the livelihood of farmers; this should be further supported by empirical and quantitative research. Rural land use transition of mountainous areas improves natural restoration and is related to socioeconomic development. Rural land consolidation of mountainous areas should conform to land use transition,with the goal of shifting from the increase of cultivated land to the synergies of ecological and environmental protection.     

1950–2011年黄河入海水沙通量变化的阶段性与多尺度特征(英文)

This paper examines the changes in the time series of water discharge and sediment load of the Yellow River into the Bohai Sea. To determine the characteristics of abrupt changes and multi-scale periods of water discharge and sediment load, data from Lijin station were analyzed, and the resonance periods were then calculated. The Mann-Kendall test, order clustering, power-spectrum, and wavelet analysis were used to observe water discharge and sediment load into the sea over the last 62 years. The most significant abrupt change in water discharge into the sea occurred in 1985, and an abrupt change in sediment load happened in the same year. Significant decreases of 64.6% and 73.8% were observed in water discharge and sediment load, respectively, before 1985. More significant abrupt changes in water discharge and sediment load were observed in 1968 and 1996. The characteristics of water discharge and sediment load into the Bohai Sea show periodic oscillation at inter-annual and decadal scales. The main periods of water discharge are 9.14 years and 3.05 years, whereas the main periods of sediment load are 10.67 years, 4.27 years, and 2.78 years. The significant resonance periods between water discharge and sediment load are observed at the following temporal scales: 2.86 years, 4.44 years, and 13.33 years. Water discharge and sediment load started to decrease after 1970 and has decreased significantly since 1985 for several reasons. Firstly, the precipitation of the Yellow River drainage area has reduced since 1970. Secondly, large-scale human activities, such as the building of reservoirs and floodgates, have increased. Thirdly, water and soil conservation have taken effect since 1985.     

Evolution characteristics and drivers of the water level at an identical discharge in the Jingjiang reaches of the Yangtze River

The operation of large-scale reservoirs have modified water and sediment transport processes, resulting in adjustments to the river topography and water levels. The polynomial fitting method was applied to analyze the variation characteristics of water levels under different water discharge values in the Jingjiang reach of the Yangtze River from 1991–2016. The segregation variable method was used to estimate the contributions of the varied riverbed evaluation, the downstream-controlled water level, and the comprehensive roughness on the altered water level at an identical flow. We find that low water levels in the Jingjiang reach of the Yangtze River from 1991–2016 are characterized by a significant downward trend, which has intensified since 2009. Riverbed scouring has been the dominate factor causing the reduced low water level while increased roughness alleviated this reduction. From 1991–2016, there was first a decrease followed by an increase in the high water level. The variation characteristic in terms of the "high flood discharge at a high water level" before 2003 transformed into a "middle flood discharge at a high water level" since 2009. The increased comprehensive roughness was the main reason for the increased high water level, where river scouring alleviated this rise. For navigation conditions and flood control, intensified riverbed scouring of the sandy reaches downstream from dams enhanced the effects that the downstream water level has on the upstream water level. This has led to an insufficient water depth in the reaches below the dams, which should receive immediate attention. The alteredvariation characteristics of the high water level have also increased the flood pressure in the middle reaches of the Yangtze River.     

Land use change and its ecological effect in Qian'an County of Jilin Province

Based on GIS and statistical methods, with the help of searching historical literatures and calculating the landscape indices, the land use changes of Qian'an County in both spatial and temporal aspects from 1945 to 1996 has been analyzed in this paper. And the driving forces of land use changes and their ecological effects are discussed too. The main findings of this study are as follows: (1) Land use changed greatly in Qian'an during 1945-1996, characterized by a decrease in grassland, wetland and water bodies, and an increase in cultivated land, saline-alkali land, and the land for housing and other construction purposes. Grassland decreased by 175,828.66 ha, and cultivated land increased by 102,137.23 ha over the half century. Accordingly, the main landscape type changed from a steppe landscape to a managed agricultural ecosystem. (2) Results of correlation analysis show that the land use change in the study area was mainly driven by the socioeconomic factors.　(3) The ecological effects of land use change in the area are characterized by serious salinization, degression of soil fertility and the weakening of landscape suitability.     

STUDY ON THE STRATEGY OF EXPLOITATION NAD UTILIZATION OF LAND RESOURCES IN THE NORTHEAST MOUNTAIN REGION OF YUNNAN PROVINCE

According to the relevant laws and policies in our country,and combining with the actual conditions of the northeast mountain region of Yunnan province,the guiding principles and objectives of land utilization strategy in the region are drew up,the scheme of the regulation of land use structure in 1997～2030 is mapped out,and the strategical measures of exploitation and utilization of land resources is put forward.The main conten ts of the strategical scheme are     

河西走廊张掖绿洲土地利用/土地覆盖变化特征

Taking two false color composite Landsat 5 TM(Thematic Mapper)images of band 4,3,2taken in 1995 and 2000 as data resources,this paper carried out study on LUCC of Zhanye oasis in recent five years by interpretation according to land resources classification system of 1∶00,000 Resources and Environmental Database of the Chinese Academy of sciences.The results show that great changes have taken place in landuse/landcover in Zhangye oasis since 1995:(1)Changes of landuse structure show that cropland and land for urban construction and built-up area increased,on the contrary,water area and grassland decreased.These changes reflect the deterionration of arrangement of water and land resources between the upper and lower reaches of the Heihe River.(2)Regional differences of landuse/landcover are evident,characterized by following aspects:in Sunan County located in Qilian Mountain area,unused land and grassland decreased,but cropland and land for urban construction and built-up area inreased.In Minle and Shandan counties located in foothills,unused land,warer area and cropland decreased,but grassland and land for urban construction and built-up area increased.In Zhangye City,Linze County and Gaotai County located in plain area of the middle reaches of the Heihe River,unused land,warer area and grassland decreased,while woodland,cropland and land for urban construction and buile-up area increased.     

Water resource utilization efficiency and spatial spillover effects in China

Based on provincial panel data of water footprint and grey water footprint, and with the help of data envelopment analysis model considering and without considering the unde- sirable output, this paper estimates the water resources utilization efficiency in China from 1997 to 2011. The spatial weighting matrix based on economy-spatial distance function is established to discuss spatial autocorrelation of water resources utilization efficiency. With the help of absolute/3-convergence model, this paper concludes that there exists/%convergence in the water resources utilization efficiency. Under the conditions of considering and without considering the undesirable output, it takes about 52.6 and 5.6 years respectively to achieve the extent of half of convergence. By mean of the spatial Durbin econometric model, this paper studies spatial spillover effects of the provincial water resources utilization efficiency in China. The results are as follows. 1） With considering and without considering the undesir- able output, there is significant spatial correlation in provincial water resource efficiency in China. 2） Under the two cases, the spatial autoregressive coefficients （p） are 0.278 and 0.507 respectively, at 1% significance level. There exist the spatial spillover effects of provin- cial water resources utilization efficiency. 3） With considering the undesirable output, these factors of the education funds, the transportation infrastructure, and the industrial and agri- cultural water consumption proportion have positive impacts. These factors of foreign direct investment, the industry value-added water consumption per ten thousand yuan, per capita water consumption, and the total precipitation have negative impacts. 4） Without considering the undesirable output, the factor of GDP per laborer has a greater positive significant influ- ence on the water resources utilization efficiency. However the facts of industry value-added water consumption in ten thousand yuan and the transportation infrastructure have no sig- nificant influence. 5） Regardless of undesirable output of water resources utilization efficiency the assessment of the present real water resources utilization in China will be distorted and policy-making will be misled. The water efficiency measure considering environmental factors （such as gray water footprint） is more reasonable.     

塔里木河流域绿洲城镇发展与水土资源效益分析(英文)

This paper examines the spatial pattern of land and water resources as well as urbanization and their interactions in the Tarim River Basin, Xinjiang, China. In order to do so, we extract the data associated with efficiency of land and water resources and urbanization for the years of 1995, 2000, 2005 and 2008. Specifically the paper investigates the extent to which agglomeration of population and economic activities varies geographically and interplays with spatial pattern of resources efficiency through computation of Global Moran’s I index, Getis-Ord Gi* index and a coordinated development model. The method used provides clear evidence that urbanization, land and water resources efficiency have shown uneven spatial pattern due to oasis distribution, climate, and initial phase of urban development. Some conclusions can be drawn as follows.(1) Agglomeration and dispersion of urbanization are not consistent with those of land and water resources efficiency.(2) Evolution of the hot and cold spots of urbanization, and land and water resources efficiency, in different trajectories, indicate that there are no significant interactions between them.(3) The evidence that numbers of hot and cold spots of the three factors present varying structures reveals the dominance of unequal urban development in the study area.(4) Significant differences are also found between sub-river basins in terms of the three factors, which is a reflection of the complex physical geography of the area.(5) The degree of coordinated development of cities in the Tarim River Basin is generally low in part as a reflection of difference in spatial patterns of the three factors. It is also shown that the pattern of the degree of coordinated development is relatively stable compared with evolution of hot and cold spots of the three factors.     

Land use change and its ecological effect in Qian＇an County of Jilin Province

Based on GIS and statistical methods, with the help of searching historical literatures and calculating the landscape indices, the land use changes of Qian‘an County in both spatial and temporal aspects from 1945 to 1996 has been analyzed in this paper. And the driving forces of land use changes and their ecological effects are discussed too. The main findings of this study are as follows: (1) Land use changed greatly in Qian‘an during 1945-1996, characterized by a decrease in grassland, wetland and water bodies, and an increase in cultivated land, saline-alkali land, and the land for housing and other construction purposes. Grassland decreased by 175,828.66 ha, and cultivated land increased by 102,137.23 ha over the half century. Accordingly, the main landscape type changed from a steppe landscape to a managed agricultural ecosystem. (2) Results of correlation analysis show that the land use change in the study area was mainly driven by the socioeconomic factors. (3) The ecological effects of land use change in the area are characterized by serious salinization, degression of soil fertility and the weakening, of landscaoe suitability.     

Sedimentation effects of the Dongting Lake Area

According to a long series of measured sediment data, the sedimentation effects of the Dongting Lake Area (DLA) were studied in light of the relationship between sedimentation characteristics and resources and environment. The result shows that the long-term deposition and the impact of human activities have led to a cycle of the evolution of sedimentation pattern, resulting in sediment disaster effects and resources effects in the DLA. The main features are as follows: 1) The water beach, silt beach, lake marsh beach, reed beach and other types of beach shaped by sedimentation effects constitute the main body of the giant lake system. 2) The disaster chains are induced, i.e., sedimentation → marshland expansion and reclamation → flood function decline, fish resource depletion, biodiversity reduction disaster chain, sedimentation → marshland expansion → floods, water pollution disaster chain, sedimentation → marshland floating vegetation rising → schistosomiasis, rodents virulence disaster chain, sedimentation → flood embankment bursting → land desertification disaster chain. 3) Sedimentation has created about 98.13×104 hm2 of land in the past 55 years. Rational development and utilization of marshland resources have produced tremendous economic benefits.     

洞庭湖区的泥沙淤积效应

以1951-2005 年长系列实测泥沙等资料为依据, 从泥沙淤积特性与资源环境之间的关系上, 探讨了洞庭湖区的泥沙淤积效应。研究表明: 由于洞庭湖区始终处于淤积状态, 加之人类活动影响, 导致了泥沙淤积循环演进的格局, 以至于使泥沙的灾害性效应与资源性效应 均在湖区得到充分的显示。主要表现在: ① 塑造了水体滩地、泥沙滩地、湖草滩地、芦苇滩地等类型滩地, 构成了湖泊巨系统的主体; ② 孕育或诱发了泥沙淤积→洲滩扩展、围垦→调洪功能下降、鱼类资源枯竭、生物多样性减少灾害链: 泥沙淤积→洲滩扩展→洪涝、水质污染; 泥沙淤积→植被洲滩浮涨→血吸虫病、害鼠致害灾害链; 泥沙淤积→洪溃决堤→土地沙 化灾害链。这些淤积型泥沙灾害链给湖区直接或间接地造成巨大的经济损失。③ 近55 年间, 泥沙塑造土地约98.13×10⁸hm², 人类合理开发利用洲滩资源获得了巨大的经济效益, 就地挖沙加高防洪大堤2~3 m, 累积土石方约55×10⁸ m³, 节省了购买大量原材料的开支。     

Middle to late Holocene initiation of the annual flood pulse in Tonle Sap Lake,Cambodia

Tonle Sap Lake, Cambodia, possesses one of the most productive inland fisheries in the world and is a vital natural resource for the country. The lake is connected to the Mekong River via the Tonle Sap River. Flow in the Tonle Sap River reverses seasonally, with water exiting the lake in the dry season and entering the lake during the summer monsoon. This flood pulse drives the lake’s biological productivity. We used Sr, Nd, and Pb isotopes and elemental concentrations in lake sediment cores to track changes in the provenance of deposits in Tonle Sap Lake. We sought to determine when the lake first began to receive water and sediment input via the Mekong River, which initiated flood pulse processes. The transition from a non-pulsing lake to the Mekong-connected system is marked by shifts to values of ⁸⁷Sr/⁸⁶Sr, ε_Nd, and ²⁰⁷Pb/²⁰⁴Pb that are characteristic of Mekong River sediments. In addition, magnetic susceptibility increased and sediment elemental composition changed. Elemental (P) measures point to enhanced phosphorus loading and C/N and isotope ratios of bulk organic matter indicate a shift to greater relative contribution of organic material from aquatic versus terrestrial environments, coinciding with the initiation of flood pulse processes. On the basis of radiocarbon dating in two cores, we estimate the initiation of the annual flood pulse occurred between ~4,450 and 3,910 cal year BP.     

Water and sediment chemistry of Lake Pumayum Co,South Tibet,China: implications for interpreting sediment carbonate

A combination of water and sediment chemistry was used to investigate carbonate production and preservation in Lake Pumayum Co (altitude 5,030 m a.s.l.), south Tibet, China. We compared the chemical composition of lake water in various parts of the lake with that of input rivers and found that the loss of Ca²⁺ results from calcite sedimentation induced by evaporation and biogenic precipitation. This is supported by evaporation data from the catchment and δ¹⁸O measurements on water. Results suggest that CaCO₃ is the predominant carbonate in this lake. There is a positive correlation in the sediments among concentrations of total inorganic carbon (TIC), Ca, total organic carbon (TOC), and total nitrogen, confirming that most carbonates in sediment are endogenic. The Jiaqu River is the largest inflow to Lake Pumayum Co and has a strong influence on both lake water chemistry and sediment composition. The river and lake bathymetry influence carbonate sedimentation by affecting water flow velocity and growing conditions for macrophytes. Different carbon contents and relationships between TIC and TOC in the two long cores from different depths in the lake reveal that hypolimnetic conditions also influence carbonate precipitation and preservation.     

Rates of sediment deposition in a hypersaline lake in the northern Great Plains,western Canada

Remarkably high rates of sedimentation (up to nearly 60 kg m⁻² yr⁻¹) are documented for offshore areas of Freefight Lake, a deep, hypersaline, meromictic lake in the northern Great Plains of Canada. Most material in the offshore sediment traps consists of soluble and suparingly soluble endogenic salts. Deposition of allogenic sediment is minor. The observed high sedimentation rates are in response to several mechanism: (i) freeseout precipitation of salts from the mixolimnion; (ii) redistribution of shallow water endogenic precipitates by turbidity flows and interflow processes; and (iii) precipitation of salts from within the monimolimnion Because the bottom water mass of the lake is essentially isothermal and isochemical, large scale temperature induced remobilization of these salts at or near the sediment-water interface is unlikely. Similarly, the morphology of the basin suggests that resuspension of bottom sediment by waves in the offshore areas of the basin is negligible. Although the sedimentation rates observed in Freefight Lake are extraordinarily high and considerably greater than other modern lacustrine sedimentation rates documented in the literature to date, the observed rates are entirely compatible with suggested accumulation rates of ancient evaporite sequences. Palliser Tringle Global Change Contribution Number 6.     

Historical change in lake sedimentation in Lake Takkobu, Kushiro Mire, northern Japan over the last 300 years

Environmental degradation, including shallowing, deterioration of aquatic habitat and water pollution, has arisen from the inflow of fine sediment to Lake Takkobu in northern Japan. The lake has experienced gradual environmental degradation due to agricultural development, which has introduced both fine sediment and sediment-associated nutrients into the lake. We have reconstructed the history of sediment yield to Lake Takkobu in Kushiro Mire over the last 300 years and have examined trends with reference to land-use development. Fifteen lake sediment core samples were obtained, and various physical variables of lake sediments were analyzed and dated using ¹³⁷Cs and tephrochronology. The physical variables showed that all points contained mainly silt, except for two points close to the river mouths, where the mean diameter was < 35 μm. The peaks were defined as a “signal” when the physical variables were synchronous in a profile. These were created by floods and engineering works constructing drainage systems. The signal of canal construction in 1898 was detected in all core points. Lake Takkobu core samples contained two tephra layers. From the refractive indices of dehydrated glasses, the lower tephra layer was identified as Ko-c2 (1694) and the upper tephra layer as Ta-a (1739). A clear peak in the ¹³⁷Cs concentration was detected at all the sampling points, except for the site close to the Takkobu River. This site showed two peaks in the ¹³⁷Cs concentration, which was attributed to perturbation from flood events and a drainage project. The maximum ¹³⁷Cs concentration was identified as the sediment surface from 1963, enveloped by the 1962 and 1964 signals. The sediment yield averaged over the last 300 years for Lake Takkobu was reconstructed for four periods using the signal, tephra and ¹³⁷Cs as marker layers. The sediment yield under the natural erosion condition for the first two periods was 226 tons/year from 1694 to 1739 and 196 tons/year from 1739 to 1898. The development of the Takkobu watershed started in 1880s with partial deforestation and channelization in 1898, 1959, and 1962 leading to an increased sedimentation yield of 1016 tons/year from 1898 to 1963. Continued deforestation, channelization works in 1964, road construction in 1980–1990s, as well as agriculture development caused a further increase to 1354 tons/year from 1963 to 2004. Compared to the averaged natural sedimentation yield of 206 tons/year until 1898, initial land-use development in a catchment accelerated lake sedimentation, indicated by the 5-fold sediment yield. With increasing agricultural development since 1960s, sedimentation yields were highest for 1963–2004; a 7-fold increase compared with pre-impact conditions. To reduce sediment yield, riparian buffers along the rivers should be preserved or rebuilt, and sluices may function effectively during short-term periods of flooding. Environmental management policy and laws restricting uncontrolled and inappropriate land-use might help in addition to ensure longer-term environmental health by reducing the sedimentation rate.     

开封市黄河滩区土地资源规避洪水风险的安全利用

基于ArcGIS与ERDAS遥感影像制图软件,利用2007年SPOT2.5m分辨率遥感影像,结合实地调查,详细编绘了开封市段黄河河道边界、开封段黄河滩区土地资源的利用现状。采用1992~2007年最大洪峰时期的TM影像与沿河水文站点的观测资料,提取1992~2007年7个典型日期的河道行洪边缘线,与本底数据叠加,编制了开封段不同常遇洪水流量下滩区淹没范围。按照黄河下游二维水沙数学模型,采用2004年汛后河道大断面资料,计算生成不同流量级大洪水在滩区的可能淹没范围图(淹没区边界)。在此基础上,结合土地资源管理与河道行洪安全性的要求,总结当前黄河下游滩区利用开发的现状与存在问题,制订土地安全利用规避洪险的原则,规划土地安全利用分区,分为临河风险缓冲带、近河宜耕地带、相对稳定利用带(中风险带)和稳定利用带。提出了黄河滩区土地资源合理安全利用的对策。     

Spatial-temporal differences in in-stream flow requirement based on GIS： A case study of Yan＇an region,northern Shaanxi

Although water has the central function of the bloodstream in the biosphere especially in arid or semi-arid regions such as Yah＇an region in northwestern China, yet the very limited attention is paid to the role of the water-related processes in ecosystem. In this research, based on continuous nearly 50-year data including runoff volume, sediment discharge as well as sediment accretion from hydrographic stations, and 10-year information of water quality from pollution monitoring stations, the method for measuring in-stream flow requirement has been put forward supported by experiential models and GIS spatial analysis. Additionally, the changes of in-stream flow requirement for environment and economic development have been addressed from spatial-temporal dimensions. The results show that： （1） According to the central streams in Yan＇an region, mean annual in-stream flow requirement reaches 1.0619 billion m^3, and the surface water for economic exploitation is 0.2445 billion m3 （2） Mean annual in-stream flow requirement for sediment transfers in flood period occupies over 80% of the integrated volume in a year. （3） From the 1950s to 1970s, in-stream flow requirement for sediment transfers is comparatively higher, while from the 1980s to 1990s, this requirement presents a decreasing tendency.     

黄河内蒙古段淤积泥沙洪水冲刷效应

为了探讨黄河内蒙古段淤积泥沙的洪水冲刷效应,于2012年对其三湖河口水文站河道监测断面汛期（7-10月）流量、悬移质泥沙含量以及洪水期间（2012年8月20日-2012年10月1日）悬移质泥沙含量、粒度百分含量的垂直变化特征与流量的关系进行了统计和分析。结果表明：（1）该次洪水具有峰高量大、洪峰过程在河段内持续时间长、洪水起涨和消退缓慢、峰形矮胖的特点;（2）洪水过程中,小于0.05 mm的细颗粒泥沙在2 000 m³·s^-1左右的流量下就能输移通过,在2 000～2 400 m³·s^-1时输沙强度最大,对河道淤积泥沙可以达到输沙最优的效果;而粒径大于0.05 mm的泥沙输移的效果不好。     

Sediment accumulation of Dianchi Lake determined by 137Cs dating

The water quality of Dianchi Lake declines quickly and the eutrophication is getting serious. To identify the internal pollution load of Dianchi Lake it is necessary to evaluate its sediment accumulation. Sedimentation rates of Dianchi Lake are determined by ¹³⁷Cs dating. However, ¹³⁷Cs vertical distribution in sediment cores of Dianchi Lake has special characteristics because Dianchi Lake is located on the southeast of the Qinghai-Tibet Plateau, the Kunming quasi-stationary front is over the borders of Yunnan and Guizhou where the specific precipitation is distributed. Besides 1954, 1963 and 1986 ¹³⁷Cs marks can be determined in sediment cores, a ¹³⁷Cs mark of 1976 representing the major period of ¹³⁷Cs released from China unclear test can be determined and used for an auxiliary dating mark. Meanwhile Dianchi Lake is divided into seven sections based on the water depth, basin topography, hydrological features and supplies of silt and the lakebed area of each section is calculated. The mean annual sedimentation rates for seven sections are 0.0810, 0.1352, 0.1457, 0.1333, 0.0904, 0.1267 and 0.1023 g/cm²a in 1963–2003, respectively. The gross sediment accumulation of the lake is 26.18×10⁴ t/a in recent 17 years and 39.86×10⁴ t/a in recent 50 years. Foundation: National Natural Science Foundation of China, No.40771186; The Key Project of the State Key Laboratory of Soil Sustainable Agriculture, Nanjing Institute of Soil Sciences, Chinese Academy of Sciences, No.5022505 Author: Zhang Yan (1962–), Ph.D and Associate Professor, specialized in environmental change.