Nansi Lake Basin Research Articles

Subpixel impervious surface estimation in the Nansi Lake Basin using random forest regression combined with GF-5 hyperspectral data

Impervious surfaces (ISs) are significant indicators of the overall environmental health of watersheds. Monitoring the IS spatial patterns of watersheds is helpful for improving water management and regional pollution assessment. A random forest regression (RFR) approach was developed to estimate the subpixel IS percentage (ISP) from Chinese GF-5 hyperspectral imagery in 30 m pixels in the Nansi Lake Basin. Initially, object-based image analysis and overlay analysis were adopted to generate a very high-resolution ISP reference dataset using GF-1 multispectral imagery. Subsequently, an RFR-based ISP prediction model was established and evaluated using training and validation samples, respectively. The experimental results demonstrated that the proposed method shows a good performance with a root mean square error of 0.17, a mean absolute error of 0.15, and an R2 value of 0.89. Meanwhile, both band 10 and band 53 of GF-5 made the highest contributions to ISP modeling. Further comparison with other machine learning algorithms revealed that the RFR-based ISP model outperforms support vector machine regression and partial least squares regression, demonstrating the potential usability of the proposed method in ISP estimation from hyperspectral imagery.

The fuzzy comprehensive evaluation (FCE) and the principal component analysis (PCA) model simulation and its applications in water quality assessment of Nansi Lake Basin, China

The Fuzzy Comprehensive Evaluation (FCE) and the Principal Component Analysis (PCA) were simulated to assess water quality of the Nansi Lake Basin, China. The membership functions were established via the Nor-Half Sinusoidal Distribution Method, and the weight was calculated via the Exceeding Standard Multiple Method. To enhance the efficiency of extracting principal pollutant, the eigenequation was solved through the Jacobi Method, and the principal components were extracted based on eigenvalue, contribution ratio, accumulating contribution ratio, principal component loading and score. Water quality classification based on “National Surface Water Environmental Quality Standards of China (GB3838-2002) was used to assess the water quality. Considering the difference of the temporal and spatial distribution in average, water quality of Level I was 28.9%, 28.1%, 25.1%, 25.6%, respectively in spring, summer, autumn, and winter, which suggested that water quality in spring and summer was better than in autumn and winter. The order of water quality was Zhaoyang Lake (Level I) > Nanyang Lake (Level I) > Dushan Lake (Level III) > Weishan Lake (Level III and IV). There were four extracted principal components that can replace the fourteen pollutant indexes for assessing water quality. According to the annual mean data of the 1st principal components, the most important pollutions were heavy metals, including As (0.933), Hg (0.931), Cd (0.929), Cr(VI) (0.926), Pb (0.925), and Cu (0.534). It is proved that the combined FCE-PCA model could provide valuable information in the water quality assessment for the Nansi Lake Basin.

南四湖流域生态系统服务功能对土地利用变化的响应研究

南四湖流域生态系统服务功能对土地利用变化的响应研究

Research on LUCC in Nansi Lake Area Based on GF-1 Image

Based on the high-resolution images of Nansi Lake, the multi-scale segmentation of eCognition and the object-oriented nearest neighbor method are used for classification and visual interpretation and correction.The results show that the classification method is relatively fast, the boundary of the ground class fits natural objects, the classification parameters can be classified based on panchromatic bands, and other spectral bands and indexes can be subdivided.According to the results, the order of land area in the Nansi lake basin is irrigated land > lake region > urban land > aquaculture water surface> paddy field > unused land > navigation channel > forest land > river channel.

Assessment approach to the floodwater utilization potential of a basin and an empirical analysis from China

Water stress is increasingly intense all over the world owing to rapid economic development and global climate change. Floodwater utilization can mitigate water shortages and provide multiple water use benefits. The priority of evaluating the utilization status and potential of floodwater should be taken into account at a basin scale. However, few studies have focused on the assessment approach. This paper argues that the amount of available floodwater is a function of the ability to regulate and utilize floodwater, and that floodwater can be classified into two parts: unavailable floodwater and available floodwater. Based on this definition, the logical relationships among current floodwater utilization potential, theoretical floodwater utilization potential, and the current and theoretical amounts of available floodwater in a basin were derived using limit analysis theory. The concepts and evaluation methods of basin floodwater utilization were unified in this paper. Finally, the status and potential of floodwater utilization of the Nansi Lake Basin were evaluated. The results showed that the current and theoretical amounts of available floodwater were 1629–1808 million m3 and 2050–2155 million m3, respectively, and the current and theoretical amounts of floodwater utilization potential were 266–386 million m3 and 678–733 million m3, respectively. The application in the Nansi Lake Basin offers some practical information for assessing floodwater utilization scientifically and provides some significant guidelines for other basins.

Source apportionment of nitrogen and phosphorus from non-point source pollution in Nansi Lake Basin, China.

Nitrogen (N) and phosphorus (P) from non-point source (NPS) pollution in Nansi Lake Basin greatly influenced the water quality of Nansi Lake, which is the determinant factor for the success of East Route of South-North Water Transfer Project in China. This research improved Johnes export coefficient model (ECM) by developing a method to determine the export coefficients of different land use types based on the hydrological and water quality data. Taking NPS total nitrogen (TN) and total phosphorus (TP) as the study objects, this study estimated the contributions of different pollution sources and analyzed their spatial distributions based on the improved ECM. The results underlined that the method for obtaining output coefficients of land use types using hydrology and water quality data is feasible and accurate, and is suitable for the study of NPS pollution at large-scale basins. The average output structure of NPS TN from land use, rural breeding and rural life is 33.6, 25.9, and 40.5%, and the NPS TP is 31.6, 43.7, and 24.7%, respectively. Especially, dry land was the main land use source for both NPS TN and TP pollution, with the contributed proportions of 81.3 and 81.8% respectively. The counties of Zaozhuang, Tengzhou, Caoxian, Yuncheng, and Shanxian had higher contribution rates and the counties of Dingtao, Juancheng, and Caoxian had the higher load intensities for both NPS TN and TP pollution. The results of this study allowed for an improvement in the understanding of the pollution source contribution and enabled researchers and planners to focus on the most important sources and regions of NPS pollution.

Change of steam structure in the Nansi Lake Basin during the urbanization process since 1980s

Change of steam structure in the Nansi Lake Basin during the urbanization process since 1980s

Response of water yield function of ecosystem to land use change in Nansi Lake Basin based on CLUE-S model and InVEST model .

Land use change has an important role in hydrological processes and utilization of water resources, and is the main driving force of water yield function of ecosystem. This paper analyzed the change of land use from 1990 to 2013 in Nansi Lake Basin, Shandong Province. The future land use in 2030 was also predicted and simulated by CLUE-S model. Based on land use scenarios, we analyzed the influence of land use change on ecosystem function of water yield in nearly 25 years through InVEST water yield model and spatial mapping. The results showed that the area of construction land increased by 3.5% in 2013 because of burgeoning urbanization process, but farmland area decreased by 2.4% which was conversed to construction land mostly. The simulated result of InVEST model suggested that water yield level of whole basin decreased firstly and increased subsequently during last 25 years and peaked at 232.1 mm in 2013. The construction land area would increase by 6.7% in 2030 based on the land use scenarios of fast urbanization, which would lead to a remarkable growth for water yield and risk of flowing flooding. However, the water yield level of whole basin would decrease by 1.2 % in 2013 if 300 meter-wide forest buffer strips around Nansi Lake were built up.

The design and implementation of risk assessment model for hazard installations based on AHP–FCE method: A case study of Nansi Lake Basin

In this paper, the combined analytical hierarchy process–fuzzy comprehensive evaluation (AHP–FCE) model was built to assess the risk for hazard installations of the Nansi Lake Basin. A detailed analysis was carried out showing the relationships between the risk index and risk factors in the Nansi Lake Basin of China. To enhance the accuracy and applicability of assessing the risk, which could be influenced by the sampled human factor, an analytical mathematic method was used to show the relationship between the statistic law and the comprehensive index. The AHP–FCE model combined AHP's capabilities of multi-object and multi-rule decision with FCE's advantages in uncertainty processing. The fuzzy treatment scheme and fuzzy operation strategy were both optimized and ameliorated, so that the model could achieve the flexibility and reliability to identify and dynamically evaluate hazard installations. In this paper, the analysis of the survey data taken from the Nansi Lake Basin, scientific theory, validity in scheme, and operating feasibility of the model were validated. It is the hope that the combined AHP–FCE model will provide valuable information pertaining to environment and hazard installation risk assessments for basin systems.

Changes of rainfall and its possible reasons in the Nansi Lake Basin, China

This study investigates the changes of rainfall patterns along with the underlying reasons in the Nansi Lake Basin (NLB), China during 1960–2009. Results show that the annual rainfall increases from the northwest to the southeast of the NLB. From the temporal variation perspective, annual rainfall decreases slightly in the majority of stations. Furthermore, in spite of no pronounced trends are detected in all stations, the annual rainfall series fluctuate intensely, and present step changes around the year of 1974 and 2002. This change pattern of rainfall is verified by the approximately wet–dry–wet phase pattern, which is exhibited in the standardized departures of annual rainfall series, during the three sub-periods divided by the pre-obtained two change years. In particular, the parametric t test demonstrate that the step change in 2002 is significant. The variations in the rainy season (RS, June–September) rainfall contributed mostly to the changes in the annual rainfall, and a high similarity of change patterns between the RS and annual rainfall is also observed. The long term mean RS and annual rainfall decreases largely from the sub-period of 1960–1974 to 1974–2002, and increased largely from the sub-period of 1974–2002 to 2002–2009 in the NLB. Besides, various elements, such as the summer East Asian summer monsoon and summer Pacific decadal oscillation, may together lead to the step changes in summer rainfall over our study area.

Analysis of point source pollution and water environmental quality variation trends in the Nansi Lake basin from 2002 to 2012.

Based on the data analysis of the water environmental quality and economic development from 2002 to 2012 in the Nansi Lake basin, the correlation and change between the water environmental quality and economic development were studied. Results showed that the GDP and wastewater emissions of point source in the Nansi Lake basin had an average annual growth of 7.30 and 7.68 %, respectively, from 2002 to 2012. The emissions of chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) had the average annual decrease of 7.69 and 6.79 % in 2012, respectively, compared to 2002. Basin water quality overall improved, reaching the Class III of the "Environmental quality standards for surface water (GB3838-2002)," in which the main reason was that sewage treatment rate increased gradually and was above 90 % in 2012 (an increase of 10 % compared to 2002) with the progress of pollution abatement technology and the implementation of relevant policies and regulations. The contribution of water environmental pollution was analyzed from related cities (Ji'ning, Zaozhuang, Heze). Results indicated that Ji'ning had the largest contribution to water pollution of the Nansi Lake basin, and the pollutant from domestic sources accounted for a higher percentage compared to industrial sources. The wastewater, COD, and NH3-N mainly came from mining and washing of coal, manufacture of raw chemical materials and chemical products, papermaking industry, and food processing industry. According to the water pollution characteristics of the Nansi Lake basin, the basin pollution treatment strategy and prevention and treatment system were dissected to provide a scientific basis for prevention and control of lakeside point source pollution along the Nansi Lake.

Evaluation of water use structure and regulation to balance supply and demand in the Nansi Lake basin, China

In an established water supply system, the increasing demand for water resources caused by economic growth becomes a key issue for water resource management in China. From the water demand management perspective, this paper analyzed the mechanism of internal feedbacks among water resources, population, and economic mutual effects and established a system dynamics model to simulate the evolution and regulation of water use structure under the business-as-usual, and the high, middle, and low economic growth strategies in the Nansi Lake basin. This study showed although the regulation strategy of the middle scheme production structure can improve water use structure without impeding economy growth, the supply of water cannot meet the demand in the basin. However, a comprehensive regulation strategy can address this water shortage. By optimizing the water use structure, this comprehensive regulation strategy can lower quota of water uses and improve the efficiency of agricultural irrigation and production thus to balance water supply and demand in the basin.

Research on the Relationship between Economic Growth and Heavy Metals Pollution of Lake Sediments in Nansi Lake Basin

The Environment Kuznets Curve (EKC) hypothesis was applied to explore the relationship between economic growth and heavy metal pollution of lake sediments in Nansi Lake basin. The indicator of economic growth (IEG) was extracted from ten important economic indexes by the method of principal component analysis based on the data from 1978 to 2007. Some representative heavy metals including Hg, Cu, Br and Mn were chosen to analyze the level of heavy metals pollution in Nansi Lake basin. According to the previous research results that the deposition rate of Nansi Lake sediments was 3.5 mm/a, Kriging interpolation method was used to segment the 10.5cm core into 30 parts. The coupling results show that there is an inverted U-shaped curve between IEG and the element Br, half of an inverted U-shaped curve between IEG and Hg and Mn, and a N-shaped curve between IEG and Cu.

Analysis of Nonpoint Source Pollution and Water Environmental Quality Variation Trends in the Nansi Lake Basin from 2002 to 2012

Based on the data analysis of economic development and the water environmental quality from 2002 to 2012 in the Nansi Lake Basin in China, the correlation between economic development and the water environmental quality was researched. Analysis shows that the GDP of the Nansi Lake Basin had an average annual growth of 7.3% in 2012, and the COD andCODMnhad the average annual decrease of 7.69% and 6.79%, respectively, compared to 2002. Basin water environmental quality overall improved, reaching Class III of the “Environmental quality standards for surface water (GB3838-2002).” The pollution of the water environment was analyzed from three aspects: agricultural fertilizers and pesticides, livestock, and aquaculture. Results indicated that the water pollution of the Nansi Lake Basin mainly came from nonpoint source pollution, accounting for more than 80% of the overall pollution. The contributions of both agricultural fertilizers and pesticides account for more than 85% of the overall nonpoint source, followed by livestock and aquaculture. According to the water pollution characteristics of the Nansi Lake Basin, the basin pollution treatment strategy and prevention and treatment system were dissected, to solve the pollution problem of the Nansi Lake Basin.

Phosphorus Fractionation in the Sediment of a Natural Lake

Seven typical surface sediments were collected along the flow direction in the hypertrophic Qixinghu lake located in Nansi Lake Basin. The sediments were evaluated on the basis of phosphorus (P) fractionation by sequential extraction scheme. Sedimentary phosphorus were fractioned into six forms (Ex-P, Al-P, Fe-P, BD-P, Ca-P and Org-P) to reveal phosphorus removal mechanism. The rank order according to the content of P-fractions was Ca-P > Org-P > Al-P > Fe-P > Ex-P > BD-P. The permanent Ca-P showed considerable contribution (41.97%-73.15%) to the sedimentary P-loads. The relative contributions of Ex-P to total sedimentary phosphorus (TP) ranged from 0.91% to 4.64%, which was positively correlated with alkaline phosphatase activity (r=0.8480). TP and Org-P were positively correlated with organic matter (OM) (r=0.8577 and r=0.9237, respectively). Total phosphorus concentration in the sediment fluctuated with changes in water quality and substrate characteristics. The high content of sedimentary metal elements and OM are contributed to the phosphorus accumulation and adsorption.

Spatial-Temporal Comparative Analysis of Water Environmental Quality Features in Nansi Lake Basin

Based on monitoring data from 2006 to 2010,the surface water environmental quality features in Nansi Lake Basin were analyzed at temporal and spatial scale. The results show that the water quality in Nansi Lake basin has improved during the annual period, the wet period and dry period. In terms of CODCr and NH3-N, the proportion of water with quality of class I to III has increased, while the proportion of water with quality that was inferior to class V has decreased. The proportion of water with quality of class Ito III in NH3-N was lager than that in CODCr. The Nansi Lake basin water quality in the wet period was slightly better than that in the annual period, while the water quality in dry period was slightly worse than that in the annual period. Judging from the spatial scale, the water quality of control units in the west of Nansi Lake basin is better than those in the east of Nansi Lake basin. The control units of Guangfu River and Laoyun River in Jining were the most seriously polluted areas.

A Study on the Characteristics of Nitrogen and Phosphorus Runoff from Farmland under Wheat-Rice Rotation in Nansi Lake Basin

Field runoff pools were used to collect the surface runoff samples of wheat-rice rotation in Nansi Lake region, and different forms of nitrogen (N) and phosphorus (P) data were analyzed. The average runoff concentrations, losses, and characteristic ratios of N and P were studied. The average runoff concentrations of TN and TP in wheat–rice rotation were 0.87–7.94 and 0.08–0.81, respectively. The characteristic ratios of N and P were also observed. And the characteristic ratios of NO3--N, NH4+-N, DP, and PO43--P were 45.03%, 17.55%, 71.43%, and 54.01% in wheat–rice rotation, respectively.