土地利用/景观格局对水环境质量的影响

土地利用/景观格局已成为影响中国水环境质量的重要因素,但目前仍然欠缺土地利用/景观格局和水环境质量之间复杂关系的深入研究。以湟水流域小峡桥断面上游为例,兼顾水环境承载力与人为活动所产生的压力,建立土地利用/景观格局对水环境质量影响的结构方程模型,计算不同土地利用/景观格局指标对水环境质量的贡献率。研究表明:点源污染是湟水流域水环境质量恶化的主要因素,其贡献率最大(37.3%);而土地利用/景观格局的4个指标(不透水面面积占比、建设用地中绿地面积占比、湿地连通性和湿地聚集度)对水环境质量的贡献率相对较大,分别为9.14%、 7.91%、 7.44%和6.96%。加大点源污染控制力度、增强湿地连通性与聚集度、增大建设用地中绿地面积并减少不透水面面积是改善湟水流域小峡桥断面上游水环境质量的有效措施。     

额济纳绿洲近20年来土地覆被变化

土地利用/土地覆被变化研究是近年来全球环境变化研究的焦点之一。根据黑河下游额济纳绿洲土地生态分类,利用1982年与2000年2期TM遥感数据对比和野外实地调查,采用景观生态空间分布格局分析方法,分为河岸乔木林、河岸灌草林、荒漠稀疏灌丛、荒漠稀疏草地、河道与水域、盐碱化土地、城镇、戈壁、流动沙丘和剥蚀地山丘陵, 从各类土地分布面积变化和类型转移趋向与幅度两个方面,分析了额济纳绿洲20年来土地覆被变化。结果表明：①土地覆被类型结构发生了较大变化,河岸乔木林面积萎缩了0.97％、斑块数减小了376,而河岸灌草林增加了0.92％,数量减小1 316;而％LAND指数荒漠稀疏灌丛由4.49％增加到5.65％,由于中游来水量的锐减,河道和水域的斑块数由40个减少到6个,％LAND指数减小了0.15％。与此同时流动沙丘％LAND指数增加了0.42％。②近20年来以胡杨为主的河岸乔木林和荒漠稀疏草地减小了45.02％和14.55％,相应地以柽柳为主的河岸稀疏灌草地和荒漠稀疏灌丛增加了35.03％和25.88％;河岸乔灌林向河岸灌草林景观转移概率为45.95％,向荒漠稀疏灌丛和稀疏草地转移了0.78%和3.01％,向戈壁转移了10.87%;河岸灌草林景观类型向河岸乔灌林转移8.06％,向稀疏灌丛和稀疏草地转移10.95%和19.64%,向戈壁转移11.88％;③额济纳绿洲具有从河岸乔木→河岸灌草地→荒漠稀疏灌丛快速演化的趋势。     

Simulation of spatial and temporal distribution on dissolved non-point source nitrogen and phosphorus load in Jialing River Watershed,China

Jialing River, which covers a basin area of 160,000 km² and a length of 1,280 km, is the largest tributary of the catchment area in Three Gorges Reservoir Area, China. In recent years, water quality in the reservoir area section of Jialing River has been degraded due to land use and the rural residential area induced by non-point source pollution. Therefore, the semi-distributed land-use runoff process (SLURP) hydrological model has been introduced and used to simulate the integrated hydrological cycle of the Jialing River Watershed (JRW). A coupling watershed model between the SLURP hydrological model and dissolved non-point source pollution model has been proposed in an attempt to evaluate the potential dissolved non-point source pollution load; it enhances the simulation precision of runoff and pollution load which are both based on the same division of land use types in the watershed. The proposed model has been applied in JRW to simulate the temporal and spatial distribution of the dissolved total nitrogen (DTN) and dissolved total phosphorus (DTP) pollution load for the period 1990–2007. It is shown that both the temporal and spatial distribution of DTN and DTP load are positively correlated to annual rainfall height. Land use is the key factor controlling the distribution of DTN and DTP load. The source compositions of DTN and DTP are different, where average DTN pollution load in descending order is land use 67.2%, livestock and poultry breeding 30.5%, and rural settlements 2.2%; and for DTP, livestock and poultry breeding is 50%, land use 48.8%, and rural settlements 1.2%. The contribution rates of DTN and DTP load in each sub-basin indicate the sensitivity of the results to the temporal and spatial distribution of different pollution sources. These data were of great significance for the prediction and estimation of the future changing trends of dissolved non-point source pollution load carried by rainfall runoff in the JRW and for studies of their transport and influence in the Three Gorges Reservoir.     

Using landscape indicators and Analytic Hierarchy Process (AHP) to determine the optimum spatial scale of urban land use patterns in Wuhan,China

Quantifying land use patterns and functions is critical for modeling urban ecological processes, and an emerging challenge is to apply models at multiple spatial scales. Methods of determining the optimum scale of land use patterns are commonly considered using landscape metrics. Landscape metrics are quantitative indicators for analyzing landscape heterogeneity at the landscape level. In this study, due to their widespread use in urban landscape analyses and well-documented effectiveness in quantifying landscape patterns, landscape metrics that represent dominance, shape, fragmentation and connectivity were selected. Five metrics include Patch Density, Contagion, Landscape Shape Index, Aggregation Index and Connectivity. Despite a wide application of landscape metrics for land use studies, the majority mainly focuses on the qualitative analysis of the characteristics of landscape metrics. The previous models are limited in exploring the optimum scale of land use patterns for their lack of quantitation. Therefore, taking the City of Wuhan as an example, the land use unit was treated as a patch, and the landscape pattern metrics at different spatial scales were calculated and compared so as to find the optimum one. Furthermore, a mathematical model of landscape metrics was proposed to quantify the scale effect of urban land use patterns, generating a complementary tool to select the optimum scale. In addition, Analytic Hierarchy Process (AHP) was introduced to determine the respective weights of the chosen landscape metrics in this model. Fractal dimension was ultimately applied to verify the chosen optimum scale of our study region. The results indicated that 60 m is confirmed to be the optimum scale for capturing the spatial variability of land use patterns in this study area.     

Watershed landscape indicators of estuarine benthic condition

Do land use and cover characteristics of watersheds associated with small estuaries exhibit a strong enough signal to make landscape metrics useful for identifying degraded bottom communities? We tested this idea with 58 pairs of small estuaries (<260 km²) and watersheds in the U.S. Mid-Atlantic coastal plain (Delaware Bay to Chesapeake Bay). We considered 34 landscape metrics as potential explanatory variables and seven estuarine parameters as response variables. We developed three logistic regression models: one to calculate the probability of degraded benthic environmental quality (BEQ), as defined by chemical parameters, and two for the probability of degraded estuarine bottom communities, one using a benthic index (BI) and a second using the total number of bottom-dwelling species (TNBS, consisting of benthic macroinvertebrates and fishes). We evaluated the discriminatory power of the models with ROC (receiver operating characteristic) curves of sensitivity and specificity. All three models showed excellent discrimination of high and low values. A model using the sum of all human land uses and percent wetlands correctly classified BEQ in 86% of the cases; low benthic index and low total number of bottom species were each associated with degraded BEQ (p<0.01). The BI model used percent riparian urban, riparian wetlands, and agriculture on steep slopes (76% correct classification) and correctly predicted high-low benthic index of an independent data set 79% of the time (p<0.05). The TNBS model used percent wetlands, riparian wetlands, and riparian agriculture (74% correct classification). Watersheds with higher percentages of urban and agricultural land uses were associated with lower benthic environmental quality, benthic index, and biodiversity, whereas those with higher percentages of wetlands were associated with higher numbers. As human development of watersheds increases, statistical prediction rules developed from landscape metrics could be a cost-effective method to identify potentially threatened estuaries.     

Land-use change and its ecological responses: a pilot study of typical agro-pastoral region in the Heihe River,northwest China

Although rapid land-use change has taken place in many arid and semi-arid regions of northwestern China, relatively less attention has been paid to studying the characteristics of land use change, as well as the ecological responses of land use change in these regions, especially in fragile agro-pastoral regions. This paper analyzes the land use change and its ecological responses during 1985–2005 based on the landscape metrics change and transition matrix of land use types by the combined use of satellite remote sensing and geographical information systems in Shandan County, a typical agro-pastoral region in the middle and upper reaches of Heihe River, northwest China. The results indicate significant changes in land use have occurred and the landscape has become more continuous, clumped and more homogeneous within the examined area. Land use change was mainly characterized by remarkable expansion of barred land and water area, slight increase of cropland and urbanized land, and evident shrinkage of grassland and woodland. The study also demonstrates that the land cover suffered severe degeneration and the ecological environment tended to deteriorate over the study period, mainly as follows: grassland degradation, land desertification and ecosystem services decline.     

基于面向对象分类技术的雅砻江流域地表信息提取与分析

雅砻江是川西最重要的河流之一,雅砻江流域内的土地利用情况与流域内的生态环境及河流水质密切相关。以Landsat 8 OLI遥感影像为数据源,采用面向对象的分类方法,建立分类规则,获取研究区的土地利用情况,利用Fragstats 4.2软件进行区域景观空间分布特征分析。结果表明:采用面向对象的分类方法的分类总体精度达到8711%,Kappa系数达到0.855。雅砻江流域内的区域整体景观连接性较好。草地和林地是研究区的主导类型,整体看分布较为集中。     

Land-use change and its environmental impact in the Heihe River Basin, arid northwestern China

Rapid land-use change has taken place in many arid and semi-arid regions of China over the last decade as the result of demand for food for its growing population. The Heihe River Basin, a typical inland river basin of temperate arid zone in northwestern China, was investigated to assess land-use change dynamics by the combined use of satellite remote sensing and geographical information systems (GIS), and to explore the interaction between these changes and the environment. Images were classified into six land-use types: cropland, forestland, grassland, water, urban or built-up land, and barren land. The objectives were to assess and analyze landscape change of land use/cover in Heihe River Basin over 15 years from 1987 to 2002. The results show that (1) grassland and barren land increase greatly by 22.3, and 268.2 km², respectively, but water area decreased rapidly by 247.2 km² in the upper reaches of Heihe River Basin; (2) cropland and urban or built-up land increased greatly by 174.9, and 64.6 km², respectively, but grassland decreased rapidly by 210.3 km² in the middle reaches of Heihe River Basin; and (3) barren land increased largely by 397.4 km², but grassland degraded seriously and water area decreased obviously by 313.3, and 21.7 km², respectively in the lower reaches of Heihe River Basin. These results show that significant changes in land-use occur within the whole basin over the study period and cause severe environmental degradation, such as water environmental changes (including surface water runoff change, decline of groundwater table and degeneration of surface water and groundwater quality), land desertification and salinization, and vegetation degeneracy.     

Monitoring and analysis of changes in a wetland landscape in Xingzi county

Wetlands play an important role in water conservation, environmental protection, and biodiversity conservation. Remote sensing is an economical and efficient technique for wetland monitoring which can limit disturbance in sensitive areas and support wetland conservation. In this paper, we used three phases of Thematic Mapper/Enhanced Thematic Mapper plus (TM/ETM+) remote sensing images from October 1989, October 1999, and October 2009 to study wetlands in Xingzi County. The images were segmented using the object-oriented remote sensing image interpretation software eCognition Developer 8.64, then segmented images were classified by slope, digital elevation model (DEM) data, Normalized Difference Vegetation Index (NDVI), Specific Leaf Area Vegetation Index (SLAVI), and Land and Water Masks (LWM) index to produce land type classification maps. Land use change information was obtained by analyzing the superposition of two classification maps of the wetland area from different years. The results showed that landscape patches in Xingzi County displayed fragmentation in their spatial distribution over time. Based on an index of changes in landscape patches, the fastest growing landscape type is grassland, while the fastest decreasing type is irrigated land. Dominant driving factors of changes in Xingzi County’s wetland landscape are population growth and policy changes.     

Relationship between the variation of water quality in rivers and the characteristics of watershed at Miyun,Beijing, China

Based on the characteristics of land use and drainage network of the upper watershed of the Miyun Res-ervoir, Beijing, 26 monitoring and sampling sites were selected in different sub-catchments. Temporal and spatial variations in nutrient loss were dealt with in this paper in terms of the monitoring data on the water quality of the main tributaries flowing into the Miyun Reservoir. In combination with the monitoring data on water quality, the impacts of watershed characteristics including land-use type, landscape pattern, and drainage density were assessed, The concentrations of nutrients in the rainy season are higher than those in other seasons, and the concentrations of NO3--N are linearly related to those of total N which is the main form of nitrogen present in the fiver water. The concentrations of nitrogen become higher toward the reservoir along the main rivers. The seasonal variation of ni-trogen in the watershed affected by intensive human activities is very obvious; in the watershed with steady or low water flow, the seasonal variation of nitrogen is less obvious. Forest land and grassland can trap and filter nitrogen effectively. Land-use pattern also has important impacts on the loss of nitrogen. The concentrations of nitrogen and phosphorus in the water bodies show great temporal and spatial variations. On a temporal scale, the concentrations of TN and TP in the rainy reason are higher than those in other seasons. On a spatial scale, the concentrations of TN and NO3--N in the Qingshui River and Chaohe River are highest all the time. The spatial variation of TP is distinct, being obvious at sampling sites near villages. The form of nitrogen and phosphorus loss varies in different hydrological seasons. Dissolved nitrogen and phosphorus are the main forms in streams in non-rainy seasons, the dissolved nitro-gen and total nitrogen decrease in percentage in the rainy season. Particulate nitrogen and phosphorus are the main forms in some rivers. The concentrations of TN and NO3--N from orchards and villages are high whereas those from forest land are lowest. Land-use pattern has impacts on TN and NO3--N losses, at the sampling sites near the source landscape, the concentrations are higher than those at the sampling sites near the sink landscape. Water quality of the rivers which flow into the Miyuan Reservior is influenced by the composition of adjacent soils.     

Spatial evaluation of phosphorus retention in riparian zones using remote sensing data

Riparian zones act as important buffer zones for non-point source pollution, thus improving the health of aquatic ecosystems. Previous research has shown that riparian zones play an important role, and that land use has an important effect, on phosphorus (P) retention. A spatial basin-scale approach for analyzing P retention and land use effects could be important in preventing pollution in riparian zones. In this study, a riparian phosphorus cycle model based on EcoHAT was generated with algorithms from soil moisture and heat models, simplified soil and plant phosphorus models, plant growth models, and universal soil loss equations. Based on remote sensing data, model performance was enhanced for spatial and temporal prediction of P retention in the riparian zone. A modified soil and plant P model was used to simulate the soil P cycle of a riparian zone in a temperate continental monsoon climate in northern China. A laboratory experiment and a field experiment were conducted to validate the P cycle model. High coefficients of determination (R ²) between simulated and observed values indicate that the model provides reliable results. P uptake variations were the same as the net primary productivity (NPP) trends, which were affected by soil temperature and moisture in the temperate continental monsoon climate. Beginning in June, the monthly content increased, with the maximum appearing in August, when the most precipitation and the highest temperatures occur. The spatial distribution of P uptake rates from March to September showed that areas near water frequently had relatively high values from May to August, which is contrary to results obtained in March, April, and September. The P uptake amounts for different land uses changed according to expectation. The average monthly P uptake rates for farmlands and grasslands were more than those for orchards and lowlands, which had moderate P uptake rates, followed by shrubs and forests. The spatial distribution of soil erosion demonstrated that the soil erosion came primarily from high-intensity agricultural land in the western and central areas, while the northern and eastern study regions, which were less affected by human activity, experienced relatively slight soil erosion. From the point of view of P pollution prevention, the spatial structure of riparian zones and the spatial distribution of land use around the Guanting reservoir are thus not favorable.     

Environmental changes after ecological water conveyance in the lower reaches of Heihe River,northwest China

This paper analyzed the dynamic change of the groundwater level by 6 years’ monitoring in field monitoring and the change of vegetation by the field survey and satellite remote sensing after watering in the lower reaches of Heihe River. The findings indicated: (1) the groundwater level elevation and the plant growth are closely related to the volume and the duration of watering. In general, groundwater level elevates dramatically and plants are growing much more vigorously after watering; (2) Watering incidence on groundwater keeps extending with the watering times increasing; (3) Plants grew rapidly in 100–400 m away from the water channel after watering. Watering incidence on vegetation reached 1,000 m; (4) In terms of the function and structure of ecosystem after watering in the lower reaches of Heihe River, the ecological water conveyance does not still reach the goal of ecological restoration at a large spatial scale at present. In addition, in order to solve fundamentally the problem of ecological environment worsens in the lower reaches of Heihe River, some suggestions and countermeasures are put forward.     

Exploring the factors affecting urban ecological risk: A case from an Indian mega metropolitan region

Assessment of ecological risk (ER) is a key approach to adapting and mitigating ecological deterioration in cities of developing countries. In developing countries, the ecological landscapes such as vegetation cover, water bodies, and wetlands are highly vulnerable due to rapid urban expansion. Therefore, urban ER (UER) assessment and its drivers are crucial to guide ecological protection as well as restoration. This study aims to explore the spatiotemporal pattern of UER and the impact of urban spatial form on UER in the Kolkata Megacity Region (KMR), India. This study developed a UER index and used spatial regression models across the urban centres. The ER has been assessed at city scale as well as grid-scale (2 km × 2 km and 5 km × 5 km) from 2000 to 2020. The results showed that ER has substantially increased over the last 20 years. The urban centres with very high and high ER substantially increased, i.e. from 21.95% in 2000 to 31.70% in 2020. Kolkata and its surrounding urban centres were mostly characterized by very high and high ER. ER was influenced by spatial variables (such as land use and landscapes pattern). However, remote sensing parameters were weakly related to ER. The spatial lag model (SLM) (R² = 0.8686) was found to be better fit model than spatial error model (SEM) (R² = 0.8661) and ordinary linear regression model (OLS) (R² = 0.8641). Thus, the findings of the study can improve research and a comprehensive framework for urban ecological resources and provide a scientific basis for urban ecosystem planning and restoration. In addition to this, it will guarantee the sustainable utilization of urban ecosystems.     

Land subsidence in Tianjin,China

Land subsidence has been affecting Tianjin for the past 50 years. It leads to comprehensive detrimental effects on society, the economy and natural environment. Overpumping of groundwater is the main cause. In 2008, the maximum cumulative subsidence reached 3.22 m and the total affected area nearly 8,000 km². The subsidence reached its most critical state in the early 1980s when it occurred at a rate as high as 110 mm/year. At the same time, groundwater extraction had also reached a maximum of 1,200 million m³. By importing the Luan River to Tianjin and restricting exploitation of groundwater, hydraulic heads gradually recovered after 1986 in all aquifers, and this has continued to the present in the second aquifer. The subsidence rate in urban areas dropped to 10–15 mm/year. The area of groundwater extraction expanded to the suburban area with economic growth in the 1990s, and it was shifted to the third and fourth aquifers. At present, with a subsidence rate of 30–40 mm/year, four new suburban subsidence centers have been formed. Several measures were adopted to mitigate and prevent land subsidence disasters. These included restricting groundwater exploitation, groundwater injection, prohibiting use in the specific zone, a pricing policy for water resources, advocating water-saving technology, and strict enforcement of groundwater laws. Although the subsidence area is still increasing slowly, the subsidence rate is being controlled.     

The influence of topography and land use on water quality of Xiangxi River in Three Gorges Reservoir region

A self-organizing map (SOM) was used to cluster the water quality data of Xiangxi River in the Three Gorges Reservoir region. The results showed that 81 sampling sites could be divided into several groups representing different land use types. The forest dominated region had low concentrations of most nutrient variables except COD, whereas the agricultural region had high concentrations of NO₃N, TN, Alkalinity, and Hardness. The sites downstream of an urban area were high in NH₃N, NO₂N, PO₄P and TP. Redundancy analysis was used to identify the individual effects of topography and land use on river water quality. The results revealed that the watershed factors accounted for 61.7% variations of water quality in the Xiangxi River. Specifically, topographical characteristics explained 26.0% variations of water quality, land use explained 10.2%, and topography and land use together explained 25.5%. More than 50% of the variation in most water quality variables was explained by watershed characteristics. However, water quality variables which are strongly influenced by urban and industrial point source pollution (NH₃N, NO₂N, PO₄P and TP) were not as well correlated with watershed characteristics.     

Modeling hydrological ecosystem services and tradeoffs: a case study in Baiyangdian watershed, China

Policy makers and scientists consider that land use strategies are designed to provide direct benefits to people by protecting vital ecosystem services. However, due to lack of information and evaluation methods, there is no effective and systematic tool for assessing tradeoffs between direct human benefits and ecosystem services. Land use changes influence ecosystem properties, processes and components, which are the basis for providing services. Five alternative land use scenarios (no conversion of agricultural lands, no urban expansion, agricultural expansion, forestry expansion, and riparian reforestation) were modeled for the Baiyangdian watershed, China, a densely populated, highly modified watershed with serious water shortage and pollution problems. The model InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) is designed to inform decisions about natural resource management, with an aim to align economic forces with conservation. Three ecosystem services (agricultural production, hydropower production, and water quality) were modeled to balance direct benefits and hydrological ecosystem services using InVEST. The results showed that: hydropower production was the greatest in the forestry expansion, but the lowest in agricultural expansion; agricultural production was reduced the most in forestry expansion, while retained the most in riparian reforestation. Riparian reforestation also provided the highest N and P retention and lowest N and P exportation. Riparian reforestation was the optimal land use strategy, since it protected and enhanced the vital ecosystem services without undermining direct human benefits. This research presents an initial analytical framework for integrating direct human benefits and ecosystem services in policy planning and illustrates its application. Although there are important potential tradeoffs between ecosystem services, this systematic planning framework offers a means for identifying valuable synergies between conservation and development.     

三峡库区消落带土壤磁性变化规律及成因探讨

为动态跟踪三峡库区消落带土壤物性在水位上涨后所受影响,选择重庆市忠县石宝寨镇长江左岸一带作为研究区,以消落带外同类型土壤作对照,从分析不同水位土壤的磁学性质入手,探究三峡库区蓄水前后土壤性质对环境变化的响应。库区蓄水后,不仅导致了消落带内土壤理化性质变化,还使土壤磁性空间分布在不同水位这一维度上发生显著改变。消落带监测断面数据显示,土壤磁性由蓄水前垂直方向上较稳定的分布,变为目前整体上随淹没水深增加而增高的特征;169~175 m高程附近,土壤磁性接近当地同类土壤背景值,而低于此高度尤其是低于157 m后,磁化率值迅速增高。磁性的变化是库区蓄水后土壤磁性矿物组成发生改变造成的,由热磁曲线可知,次生磁铁矿的加入是首要原因。扫描电镜下观测出的浑圆状磁铁矿的最可能来源是上游燃烧化石燃料排放的磁性外来污染物,其随江水输运至此并沉积吸附在土壤颗粒上。研究结果为间接监测污染物的迁移提供了依据。     

50余年来岩溶山地近郊村域土地利用与景观格局演变——以贵州省清镇市王家寨地区为例

选取贵州省清镇市近郊村域王家寨地区为研究对象,在GIS支持下,利用该区域1963年、1982年、2005年、2010年和2015年5期土地利用图形数据叠加分析,提取出研究区50余年来的土地利用/覆盖信息,并结合相应的社会经济统计数据,分析了其驱动力因子,其结果表明:(1)1963—2015年间,土地覆盖类型的总体变化为高被草地和平坝旱耕地明显减少,低被草地、农村居民点、工矿用地、公路用地面积大幅增加,其中,平坝旱耕地有向经济效益更高的土地利用方式转变的趋势;（2）景观格局演变的总体趋势是:自1963年起,斑块数量、斑块密度持续增加,到2015年呈下降趋势,而最大斑块指数逐年减小,形状趋于不规则,同时,近50年景观的多样性指数持续增加;（3）区内土地利用/覆盖和景观格局呈阶段性变化,从1963年到2005年,坡地土地利用活动较强,2005年后,平地土地利用强度增加、农业逐渐转型、聚落持续扩展;（4）区内土地利用及景观格局的变化主要受经济、人口和政策因素的影响。      

Assessing the impacts of land use changes on watershed hydrology using MIKE SHE

A fully distributed, physically-based hydrologic modeling system, MIKE SHE, was used in this study to investigate whole-watershed hydrologic response to land use changes within the Gyeongancheon watershed in Korea. A grid of 200 × 200 m was established to represent spatial variations in geology, soil, and land use. Initial model performance was evaluated by comparing observed and simulated streamflow from 1988 to 1991. Results indicated that the calibrated MIKE SHE model was able to predict streamflow well during the calibration and validation periods. Proportional changes in five classes of land use within the watershed were derived from multi-temporal Landsat TM imageries taken in 1980, 1990 and 2000. These imageries revealed that the watershed experienced conversion of approximately 10% non-urban area to urban area between 1980 and 2000. The calibrated MIKE SHE model was then programmed to repeatedly analyze an artificial dataset under the various land use proportions identified in the Landsat TM imageries. The analysis was made to quantitatively assess the impact of land use changes (predominantly urbanization) on watershed hydrology. There were increases in total runoff (5.5%) and overland flow (24.8%) as a response to the land use change.     

基于遥感夜间灯光数据的大连城市用地扩张的空间特征分析

为揭示大连城市用地扩张的空间分布特征,基于DSMP/OLS夜间灯光数据提取1998—2013年大连地域边界,并得到各地区的灯光阈值及地域边界分区统计面积。通过计算不同时期不同区域的城市用地增长景观格局指数,研究该市16年来的城市用地扩张方向、强度和空间景观格局变化,以揭示大连20年来城市用地扩张的空间分布特征。结果表明,城市用地扩张主要集中在沙河口区、中山区和西岗区,并以其为中心向甘井子区、旅顺口区、金州区等区域扩张。城市用地空间格局总体基本稳定,受地理条件、空间距离、经济发展和政策指引等因素的影响,城市用地扩张在不同方向上差异化显著。研究成果可作为大连城市规划的依据。