Spatiotemporal Comparative Analysis of Ecological Footprint of Poyang Lake Area and Five River Watersheds in Jiangxi Province

The Jiangxi province was divided into seven parts according to the concept of watershed,namely Poyang lake area,Fuhe,Xinjiang,Ganjiang,Xiuhe,Raohe and other river watersheds.The ecological supply and demands status of the former six parts from 2000 to 2006 was computed based on the ecological footprint model and a spatiotemporal comparative analysis to them was conducted.The result showed that:①all the studied areas had an increasing ecological deficit and they were in the status of unsustainable development;② the arable land footprint's demand were about 80% of their total footprint's demand respectively,so it was of great significance to protect and exploit arable land resources scientifically;③ the ecological deficit of grassland and forest resources can not be ignored.

Study on Changes of Grassland Landscape Pattern in Qinghai Lake Watershed

The changes of grassland landscape pattern in Qinghai Lake watershed from 1977 to 2000 were studied by adopting 3S technologies and landscape pattern analysis.The results showed that the amount of grassland landscape patch reduced,landscape fragmentation and resolution decreased,but average patch area and fractal dimension increased;through analyzing the landscape change of counties in Qinghai Lake watershed,the grassland landscape structure of Tianjun,Gangcha and Haiyan counties showed a similar change trend;but in Gonghe County grassland patch amount,landscape fragmentation and resolution increased,average patch area decreased,that is,the grassland landscape structure in this county showed a different trend.

Relationship between Water Quality and Stream Grade,Landscape Background of Hongfeng Lake Watershed in Guizhou Province

Xiayun Township watershed in the upper reaches of Hongfeng Lake is selected to study the relationship between stream grade and water quality.Turbidity and ammonium nitrogen concentration are obviously related to the stream grade,generally speaking,are positively correlated,and the water quality is degrading from the upper reaches to the lower reaches.In the future,the influence of different land use types on the water quality should be fully analyzed on the basis of enhancing the water quality monitoring to provide supports for effectively controlling non-point source pollutions and treating the water environment of Hongfeng Lake.

Phosphorus export by runoff from agricultural field plots with different crop cover in Lake Taihu watershed

Runoff and soil losses from agricultural fields are investigated as major nonpoint sources of phosphorus (P) entering lakes of Eastern China. There is relatively little information on P transport from ricefield and cropland of Lake Taihu watershed in Eastern China. Soil and P in surface runoff from a series of plots in the watershed were evaluated under simulated rainfall conditions. The objectives of this study were to evaluate the effects of crop cover, slope, and fertilizer application on P concentrations in surface runoff and eroded soil. Accumulated sediment yields varied from 7.1 to 300 g/m2 for croplands, depending on management practices. For all experiment plots, weighted average concentrations of total-P (TP), dissolved P (DP) and particulate P (PP) are much higher than 0.02 mg/L, the limiting concentration for lake water. This result showed the potential contamination of lake water from agricultural surface runoff. Accumulated TP losses were 3.8 and 18.8 mg/m2 for ricefield and cropland, respectively. The estimated annual loss of TP was 0.74 kg/(hm2 &middot a) for cropland. Most of P loss is in the PP form, which accounts for more than 90% of TP loss for cropland.

7~Be: A Geochemical Tracer for Seasonal Erosion of Surface Soil in Watershed of Lake Hongfeng, Guizhou, China

e penetrative depth in undisturbed surface soil is within 4 mm.7￣Be activity shows exponential decrease with soil depth, which is expressed as a diffusion process.7￣Be penetrative depth in undisturbed surface soil is apparently deeper in the fall (0.22-0.37 g cm￣(-2) than in the spring (0.11-0.28 g cm￣(-2) at the same site; Whereas, ￣7Be apparent activity at the top of surface soil is higher in the spring (0.3-2.2 Bq g￣(-1_) than in the fall (0.2-0.5 Bq g￣(-1) at the same site. The ￣7Be inventory (189-544 Bq m￣(-2) changes with both locations and seasons. Although the ￣7Be flux to the earth's surface increases with amount of precipitation, its maximum inventory in the soil profiles decreases to 30%-40% after the rainy period. Calculated by the diffusion equation, the erosion and accumulation rates of soil particles are agreeable with the observation in situ., which shows that the rates in fall are 1.5 times those in spring. The eroded soil particles almost all have been removed on the tablelands rather than transported into the drainage system. This indicstes that the soil erosion process in the karst region is only partial transportation within a short distance.

Hydrochemical characteristics and geochemistry evolution of groundwater in the plain area of the Lake Baiyangdian watershed,North China Plain

Water cycle and water quality in the Lake Baiyangdian watershed of the North China Plain have undergone great changes due to over-pumping of groundwater and wastewater discharge.In this paper,hydrogeochemical data was collected to analyze the hydrochemical characteristics and geochemistry evolution of groundwater.The study area was divided into two typical parts.One was in the upstream plain area,where over-pumping had resulted in significant decline of groundwater level;the other one was located in the downstream area near the Fu River and Lake Baiyangdian(Lake BYD region).In addition to the natural weathering of minerals,excessive fertilizer was also a main factor of higher ion concentration in groundwater.According to studies,due to good permeability,these regions were easy to be polluted even with deep groundwater depth.However,upstream shallow groundwater and surface water,including lake water,domestic along with industrial wastewater were all sources of present shallow groundwater in the Lake BYD region.Results indicated that anthropogenic activities rather than minerals much matter to the groundwater in these regions.Particularly,wastewater largely decided the groundwater quality,which suggested that the management and restoration of surface water quality was crucial to groundwater protection.

Salt-Lake Basin Bedrock Weathered Crust Gas Reservoir in the Altun Mountains Front of the Qaidam Basin,Western China

The bedrock weathered crust in front of the Altun Mountains in the Qaidam Basin,western China,is different from others because this is a salt-lake basin,where saline water fluid infiltrates and is deposited in the overlying strata.A large amount of gypsum infills the bedrock weathered crust,and this has changed the pore structure.Using core observation,polarized light microscopy,electron probe,physical property analysis and field emission scanning electron microscopy experiments,the characteristics of the weathered bedrock have been studied.There are cracks and a small number of dissolved pores in the interior of the weathered crust.Matrix micropores are widely developed,especially the various matrix cracks formed by tectonics and weathering,as well as the stress characteristics of small dissolved pores,and physical properties such as porosity and permeability.This‘dual structure’developed in the bedrock is important for guiding the exploration of the lake basin bedrock for natural gas.

Characteristics of Non-Point Source Pollution in the Watershed of Miyun Reservoir, Beijing, China

Nitrogen and phosphorus are the major nutrients to cause eutrophication to degrade water quality of the Miyun Reservoir, a very important drinking water source of Beijing, China, and they are mainly from non-point sources. The watershed in Miyun County was selected as the study region with a total area of 1400 km\+2. Four typical monitoring catchments and two experimental units were used to monitor the precipitation, runoff, sediment yield and pollutant loading related to various land uses in the meantime. The results show that the total nutrient loss amounts of TN and TP are \{898.07\} t/a, and \{40.70\} t/a, respectively, in which nutrients N and P carried by runoff are \{91.3%\} and \{77.3%\}, respectively. There is relatively heavier soil erosion in the northern mountain area whereas the main nutrient loss occurs near the northeast edge of the reservoir. Different land uses would influence the loss amounts of non-point source pollutants. The amount of nutrient loss from the agricultural land per unit is highest, that from forestry comes next and that from grassland is lowest. However, due to the variability of land use areas, agricultural land contributes a lot to TP and forestry lands to TN.

Influences of environmental factors on the modern 14C reservoir effects in Qinghai-Tibet Plateau lakes

The establishment of reliable age in the lake sediment profile mainly depends on the AMS 14C dating technique.However,the presence of the 14C lake reservoir effects(LREs)restricted for using radiocarbon dating in lake sediment,especially in dry and cold areas with a scarce plant cover in the Qinghai-Tibet Plateau.Hence,the discussion of influence factors of LREs is crucial.This paper selected 15 lakes(17 sediment and 3 plant samples)in the Qinghai-Tibet Plateau to examine the distribution characteristics of the modern LREs and their main influencing factors.In our study area,14 lakes were all affected by the LREs.The minimum 14C year is 5900 a BP towards the deep water area,whereas the maximum 14C year is up to 7185 a BP in the margins of Lake Heihai.The maximum 14C year is up to 7750 a BP,and the minimum 14C year is present-day carbon in the 15 lakes.One further study indicated that the LRE differences in individual lake are mostly owing to the contribution of exogenous carbonate.The results displayed that the LREs tended to increase with the increase of the salinity,moreover,the LREs of saltwater lakes or salt lakes were significantly larger than freshwater lakes due to the possible supply of old total dissolved inorganic carbon with a long residence time in the lakes.Moreover,the contribution of calcite played a significant role on the LREs.Additionally,the LREs differences are affected by the source of organic matter.The lake with groundwater supply shows large LRE due to likely being influenced by crustal and ancient CO_(2) uprising.

The Contribution of the Geospatial Information to the Hydrological Modelling of a Watershed with Reservoirs: Case of Low Oum Er Rbiaa Basin (Morocco)

Water is undoubtedly the most vital natural resource. Water use management is one of the greatest challenges that face humanity. The demand for water is continuously growing because of the population growth, the intensive urbanization and the development of industrial and agricultural activities. To face the increasing pressure on this vital resource, it is so necessary to set up the adequate instruments to ensure a rational and efficient management of this resource. In this context, the hydrological modeling is largely used as an instrument to assess the functioning of these resources at watershed scale. In addition, the use of spatial models let to depict and simulate the watershed processes at small spatial and heterogeneous scales that reflect the field reality more accurate and more realistic as possible. However, the use of spatial models requires geospatial data that must be gathered at very fine scales. The aim of this study is to highlight the contribution of geospatial data to assess the hydrologic modeling of watershed by using a spatial hydro-agricultural model, notably the SWAT model (Soil and water Assessment Tool). The study area is the Basin of Low Oum Er Rbiaa River which extends from the Al Massira dam to its outlet in the Atlantic Ocean. This watershed includes a set of dams (Daourat, Imfout and Sidi Maachou) built in waterfall fashion along the river. The objective was to simulate the hydrological functioning of this area that had never been modeled in order to assess the management of these reservoirs used essentially to produce electricity and fresh water. The implementation of the SWAT model required a spatial database that was built from topography, soil, land use and climate data. The calibration and validation of the model was carried out on a daily basis over several years (2001-2010) using The ArcSWAT tool integrated in ArcGIS software and the Parasol optimization method. The calibration of SWAT model was successfully done with 0.6 as value of Nash coefficient used commonly in hydrology to evaluate the model performance. The calibrated model was then used to estimate the hydrological balance sheet of the Low Oum Er Rbiaa to model the intermediate contribution of the three reservoirs situated in the watershed.

Determining the groundwater basin and surface watershed boundary of Dalinuoer Lake in the middle of Inner Mongolian Plateau,China and its impacts on the ecological environment

The surface watershed and groundwater basin have fixed recharge scale,which are not only the basic unit for hydrologic cycle research but also control the water resources formation and evolution and its corresponding eco-geological environment pattern.To accurately identify the boundary of the surface watershed and groundwater basin is the basis for properly understanding hydrologic cycle and conducting the water balance analysis at watershed scale in complicated geologic structure area,especially when the boundary are inconsistent.In this study,the Dalinuoer Lake located in the middle of the Inner Mongolian Plateau which has complicated geologic structure was selected as the representative case.Based on the multidisciplinary comprehensive analysis of topography,tectonics,hydrogeology,groundwater dynamics and stable isotopes,the results suggest the following:(1)The surface watershed ridge and groundwater basin divide of Dalinuoer Lake are inconsistent.The surface watershed was divided into two separate groundwater systems almost having no groundwater exchange by the SW-NE Haoluku Anticlinorium Fault which has obvious water-blocking effect.The surface drainage area of Dalinuoer Lake is 6139 km^(2).The northern regional A is the Dalinuoer Lake groundwater system with an area of 4838 km^(2),and the southern regional B is the Xilamulun Riverhead groundwater system with an area of 1301 km^(2).(2)The groundwater in the southern of regional A and the spring-feeding river are the important recharge sources for the Dalinuoer Lake,and it has greater recharge effects than the northern Gonggeer River system.(3)It is speculated that the trend of Haoluku Anticlinorium Fault is the boundary of the westerlies and the East Asian summer Monsoon(EASM)climate systems,which further pinpoints the predecessor’s understanding of this boundary line.At present,the Dalinuoer Lake watershed is proved to have gone through a prominent warming-drying trend periods,which leads to the precipitation reduction,temperature rise,human activities water usage increasement.So the hydrological cycle and lake eco-environment at watershed scale will still bound to be change,which may pose the potential deterioration risk on the suitability of fish habitat.The results can provide basic support for better understanding water balance evolution and lake area shrinkage cause as well as the ecological protection and restoration implementation of Dalinuoer Lake watershed.

Dynamic phosphorus budget for lake-watershed ecosystems

Lake eutrophication caused by excess phosphorus （P） loading from point sources （PS） and nonpoint sources （NPS） is a persistent and serious ecological problem in China. A phosphorus budget, based on material flow analysis（MFA） and system dynamic （SD）, is proposed and applied for the agriculture-dominated Qionghai Lake watershed located in southwestern China. The MFA-SD approach will not only cover the transporting process of P in the lake-watershed ecosystems, but also can deal with the changes of P budget due to the dynamics of watershed. P inflows include the fertilizer for agricultural croplands, soil losses, domestic sewage discharges, and the atmospheric disposition such as precipitation and dust sinking. Outflows are consisted of hydrologic export, water resources development, fishery and aquatic plants harvesting. The internal P recycling processes are also considered in this paper. From 1988 to 2015, the total P inflows for Lake Qionghai are in a rapid increase from 35.65 to 78.73 t/a, which results in the rising of P concentration in the lake. Among the total P load 2015, agricultural loss and domestic sewage account for 70.60% and 17.27% respectively, directly related to the rapid social-economic development and the swift urbanization. Future management programs designed to reduce P inputs must be put into practices in the coming years to ensure the ecosystem health in the watershed.

Upstream-downstream cooperation approach in Guanting Reservoir watershed

A case study is introduced and discussed concerning water dispute of misuse and pollution between up\| and down\|stream parts. The relations between water usage and local industrial structures are analyzed. Results show it is important to change industrial structures of the target region along with controlling water pollution by technical and engineering methods. Three manners of upstream-downstream cooperation are presented and discussed based on the actual conditions of Guangting Reservoir watershed. Two typical scenarios are supposed and studied along with the local plan on water resources development. The best solution for this cooperation presents a good way to help the upstream developing in a new pattern of eco-economy.

Effects of Closing Mountain for Forest Restoration in the Watershed of Miyun Reservoir, Beijing

The paper provides a systematical analysis of ecological restoration effects of natural secondary forest of closure area in Chao Guanxi Gou, Miyun County, Beijing. The results indicate that through more than twenty years of hillclosing afforestation since 1983, canopy closure has improved almost by 0.2; forest cover rate has raised from 7.2% to 93.8%; biodiversity, tree biomass and vegetation community have increased to a great extent. Compared with the average canopy closure before hillclosing afforestation in this area, it has improved to over 0.4 in average and increased by 0.10.2. The forest coverage degree has reached more than 90%. Consequently, the forest plays more important roles in intercepting precipitation, improving water storage capacity of soil, decreasing the surface runoff, and preventing soil and water loss.

Analysis of Land Use Changes in the Watershed of Nansi Lake,Shandong Province

Change of land use is related to regional food security and ecological security.This study analyzed structural changes,quantity changes and spatial changes of land resource utilization in the watershed of the Nansi Lake,Shandong Province from 2000 to 2012 on the basis of land use investigation data and relevant socio-economic data in the study period.It is to disclose the problems in the utilization of local land resources,and provide scientific support for the scientific management of land resources and sustainable development of social economy.

Impact of land use change on water quality in the Dianchi Lake watershed, Yunnan, China, 1988-2008

Land use changes occurring in China during the time period of rapid economic development are linked to the degradation of water quality in streams and lakes. This paper examines these linkages in the Dianchi Lake watershed in Yunnan in southwest China based on a twenty-year data set from 1988 to 2008. Pearson correlation analysis and simple linear regression analysis are employed to explore the relationships between land use change and water quality of two sub-basins, the Caohai Lake basin and the Waihai Lake basin, within the Dianchi Lake watershed. Land use categories more strongly correlate to water quality in the Caohai Lake basin than that in the Waihai Lake basin. The different structure of land use categories, spatial distribution of land cover, and scales of buffer zones could be the factors resulting in the dissimilarities between these two lakes. The research can provide valuable insights for policymakers into land use management in order to curb further water degradation in Dianchi Lake.

Analysis on Vegetation Succession Model and Process under Groundwater Exploitation in Subei Lake Watershed

[Objective] The study aimed to analyze vegetation succession process under groundwater mining conditions in Subei Lake watershed. [ Method] A succession model for vegetation and burial depth of groundwater level was constructed based on field survey, and it was used to pre- dict the vegetation succession rules and process according to the changes in burial depth of groundwater level in Subei Lake watershed under groundwater exploitation. [ Result~ In Subei Lake watershed, aquatic vegetation was most closely related to burial depth of groundwater level, fol- lowed by mesophytic vegetation, while psammophilous and xerophytic vegetation did not have obvious relation with burial depth of groundwater lev- el. When burial depth of groundwater level was small, dominant plants grew well, but they grew worse or died with the increase in burial depth of groundwater level. As the groundwater level fell constantly, burial depth of groundwater level went up, and vegetation succession would occur grad- ually from aquatic vegetation to mesophytic and xerophytic vegetation, from Carex L. and Iris ensata Thunb shoaly land to Achnatherum splendens shoaly lands, from Salix psammophila shrubs to Artemisia desterorum Spreng and Caragana korshinskii shrubs, and from Populus simonii to Salix matsudana. [Condusion] The research could provide scientific references for studying the relationship between groundwater resources and ecological environment in Subei Lake basin.

The Influence of Land Use and Fish Farming on the Contents of Ca²⁺, Mg²⁺, K⁺and Na⁺in Pond and Reservoir Ecosystems in an Agricultural Small Watershed, China

It is not understood well that how the effects of land use and fish farming on the contents of alkali metals (Ca2+, Mg2+, K+ and Na+) in small water bodies of pond and reservoir ecosystems at the watershed scale. In this study, the concentrations of Ca2+, Mg2+, K+ and Na+ in water bodies were measured for 103 ponds and reservoirs used as fish farming or surrounded by different agricultural land use types in the subtropical hilly watershed of Jinjing (105 km2), China. The two important environmental factors of fishing farming and agricultural land use influenced the spatial variation the contents of alkali metals. The ponds and reservoirs in residential area had significantly higher concentrations of Ca2+ and Na+ than those with other land use types, reflecting the influence of domestic wastewater. Compared with those of natural ponds with non-fish farming, no significant increase of alkali metal contents occurred in fish farming ponds, due to the regular cleaning of ponds by farmers. However, the effect of fish culture on alkali metal contents was still supported indirectly by the fact that the alkali metal contents significantly correlated with nitrate contents in fish farming ponds and but high related with that of DIP in natural ponds. The suitability assessment for irrigation on the pond water indicated that almost all of ponds were suitable for irrigation except some ponds surrounded by residential area and tea plantation. Generally, our results demonstrated that fish farming and agricultural land use affected the contents of alkali metals in ponds and reservoirs. The agricultural water irrigation would be with caution from the ponds with tea plantation and residential area in the subtropical hilly watershed.

Evaluation on Ecological Vulnerability of the Vegetation in the Subei Lake Watershed Based on Analytic Hierarchy Process

[ Objective] The research aimed to evaluate ecological vulnerability of the vegetation in the Subei Lake watershed based on analytic hierarchy process （AHP）. [ Method] From actual situation of the vegetation ecology in the Subei Lake watershed, by the established evaluation index system of vegetation ecology, based on AHP, indicator weight at each layer was determined. Comprehensive index method was used to calculate ecological fragility degree of the vegetation in each evaluation unit to evaluate ecological vulnerability of the vegetation. [ Result] Ecological vulnera- bility of the vegetation was divided into four levels, such as extremely fragile, highly fragile, moderately fragile and lowly fragile in the Subei Lake watershed. The extremely fragile area, where buried depth of the groundwater level was generally less than 1.0 meter, distributed in beach zones near the Subei Lake, and its relationship between vegetation and groundwater was close. The lowly fragile areas scattered in the ridge zone around the Subei Lake watershed, where buried depth of the groundwater level was 10.0 -40.0 meters, and their relationship between vegetation growth and groundwater depth was not obvious. Buried depth of groundwater had the most sensitive influence on vegetation ecology, and it was the key factor between utilization of groundwater resources and eco-environment protection in the study area. E Conclusion] The researches provided scientific evidence for regional eco-environment protection, rational development and utilization of water resources, and coordinated development of economy and society.

A New Understanding of Channel Patterns and Facies Models of the Shallow Lake Delta Facies of Fuyu Oil Reservoir in Songliao Basin,China

In the Fuyu Reservoir of Songliao Basin, there occur a series of well-developed peculiar shallow lake delta facies, which can be divided to such three ones as the upper delta plain subfacies, the lower delta plain subfacies, and the delta front subfacies. Among them the upper delta plain subfacies mainly grows proximal distributary channels; the lower delta plain subfacies mainly grows distal ones. The entire Fuyu Reservoir has mainly developed 7 kinds of distributary channel patterns： proximal/ distal meandering type distributary channels, proximal/distal low-sinuosity type distributary channels, proximal/distal straight type distributary channels, and subaqueous distributary channels. Among these patterns, the proximal and distal meandering type distributary channels have bigger thickness of point bar and better sorting and low content of mud; moreover, they are the major reservoirs and occur in the bottom of Quan-4th member. The sandbars of the subaqueous distributary channels have higher mud content, and serve as the poorer reservoirs, and mainly occur in the top of Quan-4th member.