Environmental Monitoring of Spatio-temporal Changes Using Remote Sensing and GIS in a Mediterranean Wetland of Northern Greece

Loss and degradation of terrestrial and aquatic habitats and degraded water quality are major environmental concerns worldwide. Especially wetlands are sensitive ecosystems that are subject to stress from human activities. Remote sensing techniques have been primarily used to generate information on land cover/use changes. Geographical Information Systems (GIS) and remote sensing can be used to provide a rapid or a large-scale understanding of lake change and in developing lake management strategies. The principal objectives of this study are to monitor and assess the spatial and temporal changes in land cover/use by using GIS, and to determine the main environmental factors affecting these changes. This paper presents a case study for the application of integrated remote sensing and GIS data for the classification and monitoring of the spatial and temporal changes in land use types. The study was conducted in a small natural wetland of Lake Cheimaditida, located in the East Mediterranean region of Northern Greece. Data analysis was conducted using GIS software. During the past several decades Lake Cheimaditida wetland has been influenced by many anthropogenic activities. The variables chosen for the assessment included condition of wetland and lake areas, present extent of wetlands relative to historic area, cover of natural habitat, wetland disturbances, etc. These variables address catchments properties that are important for maintaining and improving wetland habitats and water quality and assessment of trends useful for environmental monitoring. Land cover/land use patterns were assessed and compared using aerial photographs taken in 1945, 1969, 1982, and 1996. Over this period, reed beds enormously increased by 1,655.19%, while open-water areas and peat lands decreased by 74.05 and 99.5%, respectively. The significance of the changes in land cover distribution within the Lake Cheimaditida wetland are discussed in relation to the historical pattern of reed beds colonization, the importance of Phragmites australis in the process and the implications for strategic management of freshwater wetland resources.     

Analysing the extent (size and shape) of Lake Basaka expansion (Main Ethiopian Rift Valley) using remote sensing and GIS

This study attempted to estimate the extent of the expansion of the area of Lake Basaka over the past 50 years (1960 to 2010), using LANDSAT images, field observations, local information and topographic maps. The analysis revealed that the lake has exhibited a dramatic expansion over the past five decades. An increase in the lake water level by 7.6 m over this period resulted in flooding about 45.8 km² of surrounding areas and an incremental lake volume of about 280 Mm³. About 70% of the lake expansion was observed in the period between the 1970s and 1990s. This phenomenon coincides with the periods of remarkable land use/cover changes in the region. Furthermore, the beginning of the lake expansion coincided with the introduction of irrigated agriculture in the region, and construction of Koka Dam in the mid‐1960s in the upper Awash River Basin. This study suggests that the observed expansion trend, if it continues unabated, could result in certain socio‐economic and environmental consequences in the region in particular, and to Ethiopia in general. Groundwater inundation or salty water intrusion, for example, might occur in the area in the near future, thereby affecting the sustainability of regional irrigated agriculture. The lake has the potential to inundate the surrounding region (Matahara Sugar Estate; towns of Fantalle and Matahara) and might connect with the Awash River during the next 10–15 years. This would affect downstream irrigation developments in the Awash Basin and the livelihoods of people that depend on the basin’s water resources. The overall findings of this study emphasize the need to adopt mitigation measures before the lake expansion results in irreversible damage to the region or the basin.     

土地覆被和气候变化的水文响应研究

采用分布式水文模型SWAT研究北京地区过去10a间径流量剧减的主要原因.采用等高线→TIN→DEM的方法获取研究区分辨率较高的DEM图,基于DEM图提取流域边界、河网、子流域及相关属性,根据土壤类型与土地覆被类型的组合划分水文响应单元,实现下垫面的空间离散;采用校准和验证后率定的参数研究了10a来气候变化和土地覆被变化对径流量的影响.研究表明:10a间土地覆被变化的主要趋势是旱地城市化.过去10a间,由于土地覆被变化导致北运河年均径流量增加了10%～20%,而气候变化导致年均径流量减少了约2/3.     

Effects of Anthropogenic Influences on the Trophic State,Land Uses and Aquatic Vegetation in a Shallow Mediterranean Lake: Implications for Restoration

Lake Pamvotis, NW Greece is a shallow Mediterranean eutrophic lake that has changed drastically over the past 50 years. Strong effects, resulted mainly from anthropogenic causes, in the hydrological regime are shown for this area using long term hydrological data and a GIS system for extracting land cover/use changes. A set of aerial imagery acquired in 1945 through 2002 were used to monitor and assess the spatial and temporal changes in land cover/use, focused mainly on the lake’s surface area and its surrounding ecosystem (Natura 2000 area). The significance of the changes in land cover/use distribution within Pamvotis wetland is further discussed depicting the role of the anthropogenic influence on the fragile ecosystem that resulted in the shrinkage of lake’s habitats extent. The purpose of this analysis was to examine the long-term changes on macrophyte community composition, species occurrence and relative abundance with water quality and water level changes over the past century, using historical data, aerial photos and GIS techniques. The results showed that for the last 25 years annual water level fluctuation ranged from 70 to 159 cm. Water level starts decreasing in mid June and increasing again gradually from November until March–April. Intra annual water level fluctuation seems to be affected by land use for agricultural purpose through intensive irrigation and the summer drought as well. A dramatic decline of the submerged vegetation is apparent mainly attributed to anthropogenic pressures. Regarding the land cover/use changes, the most notable and significant alterations are concerning the urban development around the lake, the disappearance of wet meadows and the extension of reed beds. Finally it seems that water budget data as well as the response of the key eutrophication parameters are affected from both hydrological alterations and point/non-point pollution sources.     

Analysing decadal land use/cover dynamics of the Lake Basaka catchment (Main Ethiopian Rift) using LANDSAT imagery and GIS

Development of accurate classification methods for rapidly changing catchments like that of Lake Basaka is fundamental to better understanding the catchment dynamics, which were not addressed in previous studies. Thus, the aim of this study was to map the decadal land use/cover (LUC) regimes of the Lake Basaka catchment, utilizing time series of LANDSAT images and to analyse the changes that occurred at different time periods. Both unsupervised and supervised image classification systems were utilized in Earth Resources Data Analysis System (ERDAS) Imagine (9.1). Appropriate pre‐ and postprocessing also was utilized. Seven major LUC classes were identified in the final land cover maps produced after the supervised (maximum likelihood) classification exercise. The analysis results indicated the Lake Basaka catchment had experienced a drastic change in its LUC conditions over the last 4–5 decades because of rapid increases in human settlement, deforestation, establishment of irrigation schemes and Awash National Park (ANP). Approximately 18 924 ha of forest and 4730 ha of grazing lands were devastated between 1973 and 2008. At the same time, there was a shift in land cover from forests/woodlands to open woodlands, shrub and grazing lands. The land cover classifications generally were achieved at a very high overall accuracy (84.34%) and overall kappa statistics (0.802), substantiating the value of using the classified LUC in this study as an input to hydrological models. This study results provide an opportunity to better understand and quantify the hydrological response regimes of the lake catchment from the perspective of changing LUC conditions during different hydrological periods and the resulting dynamics of the lake water balance.     

塔里木河流域绿色生态空间与景观格局变化研究

本文以1990—2018年4期遥感解译数据为基础,在RS与GIS的支持下,运用景观单一动态度、转移矩阵模型及景观格局指数等方法对塔里木河流域的绿色生态空间与景观格局变化进行研究。结果表明:全流域的绿色生态空间总体呈持续减小的趋势,尤其是2010年后绿色生态空间急剧萎缩,其中减少量最大的绿色空间为草地。在各景观类型中,以建设用地和耕地等人为利用为主的人工景观增多,而以草地等自然覆被为主的自然景观减少。1990—2018年间人类活动对全流域景观格局的干扰不断增强,且在1990—2000年间,人类干扰强度最为显著;各类景观的空间分布结构均趋于失稳状态,总体呈现出景观破碎程度不断加深、景观异质性不断增强和景观格局趋于复杂化的特点。     

Microbial processes at the land–water interface,and cross‐domain causal relationships,as influenced by atmospheric deposition of pollutants in three freshwater lakes in India

The effects of long‐term atmospheric deposition of pollutant elements on the trans‐surface causative relationships at three lake sites having different catchment characteristics were investigated in this study. The selected determinants included lake productivity, bottom sediment quality, and a suite of microbial variables (microbial biomass (C_mic); basal respiration; substrate‐induced respiration; bacterial:fungal ratio; metabolic quotient; and alkaline phosphatase and FDAase activities) measured at the land–water interface, in relation to atmospheric deposition of phosphate; nitrate; ammonium; sulphate; calcium; and magnesium. The results indicated significant between‐site differences (P < 0.001) in the atmospheric deposition of phosphate (0.21–1.96 kg.h^?1.year^?1); nitrate (2.77–28.05 kg.h^?1.year^?1); ammonium (0.58–11.60 kg.h^?1.year^?1); sulphate (5.64–32.15 kg.h^?1.year^?1); calcium (4.50–30.00 kg.h^?1.year^?1); and magnesium (1.50–12.15 kg.h^?1.year^?1), as well as a consistently increasing input of these ions across time. The catchment vegetation had important effects on microbial variables that, in turn, affected lake productivity. Interfaces of woodland lake were found to be rich in phenolics, supporting low C_mic and activities. Except for alkaline phosphatase, which declined over time, atmospheric deposition of pollutant elements increased the C_mic and activities at the land–water interface. The time lag correlation analysis indicated the C_mic and lake productivity relationships were significantly altered by atmospherically driven nitrogen and phosphorus inputs, with a time lag of 2–3 years. Despite being supportive, aerial nutrient inputs appeared to have a destabilizing effect on both, microbial biomass and lake productivity variables. These observations indicate that if present atmospheric deposition trends of pollutant elements continue, it will modify the cross‐domain causative relationships of inland lentic systems over the long term. These study results are relevant for the formulation of strategies for managing freshwater tropical lakes.     

Patterns of Lake Balkhash water level changes and their climatic correlates during 1992–2010 period

The variation in Lake Balkhash water levels during the period from 1992 to 2010 and their relationship with climate dynamics were investigated in this study, using satellite altimetry data and meteorological records from climate stations located in the lake catchment basin. The altimetry‐derived water level demonstrated a general water level increase, reaching a mean value of 8.1 cm year^?1 in July 2005, with a maximum value of 342.52 m. The increased Lake Balkhash water level was accompanied by an overall upward trend in precipitation and temperature in the catchment basin during the study period. A strong increase in the winter and spring temperature was the main contributor to the general upward temperature trend, whereas a significant change of summer and autumn precipitation was the major contributor to the annual precipitation trend. Neither precipitation nor temperature increased uniformly across the entire lake drainage basin. The study results identified the most pronounced climate change occurring in the mountainous part (>2000 m above sea level) of the basin, in the upper reaches of the Ili river, which is the main water inflow to the lake. Statistical analysis indicated the Lake Balkhash water level is strongly correlated with both precipitation and temperature. The correlations were investigated for three altitudinal strata (<1000 m, 1000–2000 m, >2000 m) corresponding to the lower, middle and upper reaches of the Ili river. The best correlations were obtained for the upper reaches of the Ili river, indicating a changing snow cover and glacier equilibrium are the main factors controlling the water level trends in Lake Balkhash.     

基于SWAT模型的诺敏河流域径流对土地利用/覆被变化的响应模拟研究

土地利用/覆被变化直接反映了人类活动的影响程度,对于流域水文循环过程影响显著。本文以诺敏河流域为研究区,基于1976和2000年两期土地利用数据,结合SWAT模型定量评价了径流对土地利用/覆被变化的响应。研究结果表明:SWAT模型可以较好地模拟诺敏河流域的月径流变化过程,在研究区具有一定的适用性;相对于1976年的土地利用条件,2000年土地利用变化主要表现为林地和草地面积减小,耕地面积增加。1976-2000年间诺敏河流域土地利用变化导致年均地表径流增加了17.78%,且空间差异显著,尤其是下游的莫力达瓦达斡尔族自治旗和阿荣旗等地地表径流增加趋势更为明显,增加幅度超过20 mm。模拟研究对于诺敏河流域合理规划土地利用格局具有重要意义。     

岱海湖温排水对湖面附加蒸发量影响研究

岱海湖为一内陆封闭型湖泊。本研究利用3、7、12月份冬夏工况,综合考虑岱海湖边界条件,水面温度、密度、水面天然温度、大气温度、相对湿度等影响因子,构建温排水对岱海湖附加蒸发量影响的计算公式。经计算,电厂温排水引起的岱海湖附加蒸发损失量为:3月份为39.46万m3,7月份为73.3万m3,12月份为10.6万m3,岱海湖电厂温排水年附加蒸发水量约为678.2万m3/a。结果表明:附加蒸发量与电厂温排水量变化一致。本研究对干旱区水资源利用具有重要意义。     

河套灌区耕地-荒地-海子间水盐运移规律及平衡分析

内蒙古河套灌区引水量逐年减少,输入灌区的盐分无法有效排出,灌区内部盐分迁移规律发生了较大变化。针对此现状,通过2年现场观测试验,开展了耕地-荒地-海子间水力联系及水盐动态研究。采用土壤水动力学与溶质动力学方法,对耕地—荒地—海子系统分别构建水量和盐量平衡模型,进而揭示了耕地—荒地—海子系统间水分和盐分运移关系。结果显示:在作物生育期,土壤非饱和带及地下储水量?S分别平均减少了35.05、138.2和195.7 mm,耕地、荒地和海子均处于水分消耗状态。基于Surfer软件Grid Vector Map与耕地—荒地—海子系统水量和盐量平衡模型,发现在2017年和2018年作物生育期,耕地地下水向荒地的迁移率平均值分别为78.75%和79%;荒地地下水向海子的迁移率平均值分别为44.3%和46.3%。耕地腾发量ET平均值比荒地和海子边界的分别高32%和29.15%,海子亏水631.2～706.3 mm,如果没有水分补给,海子将会面临干涸危险;在灌溉条件下,耕地地下水盐分平均增加861.45 kg/(hm~2/a),耕地地下水迁移给荒地的平均盐量为3231.90 kg/(hm~2/a),荒地地下水迁移给海子的平均盐量为3139.7 kg/(hm~2/a)。研究结果为灌区水盐调控提供了基本依据。     

Carrying capacity and vulnerability of four Asian lakes: A comparative study

To present axes for evaluating the water resources, lake environment and water use in a lake and its watershed, a comparative study was done for four East Asian lakes; lake Kasumigaura (Japan), Lake Laguna (Philippines), Lake Songkhla (Thailand) and Lake Dianchi (China). Two axes were then determined from the relationship between: (1) water use and water supply rate, and (2) water use and water quality. To clarify the meanings ‘carrying capacity’ and ‘vulnerability’, the maximum population density in the lake basin and total nitrogen concentration in the lake water were calculated and discussed to decide the direction of environmentally sound management of the drainage basin.     

基于 RS 和 GIS 的淮河流域老王坡蓄滞洪区 土地利用/ 覆被变化

动态监测蓄滞洪区土地利用/ 覆被变化状况, 全面掌握蓄滞洪区的土地利用结构和程度, 对蓄滞洪区科学合理 运用和发展具有重要意义。采用老王坡蓄滞洪区 2000 年、 2005 年和 2010 年三期 LandsatTM 遥感数据, 分析计算 老王坡蓄滞洪区 2000 年- 2010 年土地利用/ 覆被变化状况、 单一土地利用动态度、 土地利用/ 覆被变化转移矩阵, 计算蓄滞洪区土地利用程度变化指标。研究表明, 11 年来老王坡蓄滞洪区土地利用结构和强度都发生显著变化, 且仍处于发展变化期。     

Poyang Lake basin: a successful, large-scale integrated basin management model for developing countries

Protection of water environment while developing socio-economy is a challenging task for lake regions of many developing countries. Poyang Lake is the largest fresh water lake in China, with its total drainage area of 160,000 km2. In spite of rapid development of socio-economy in Poyang Lake region in the past several decades, water in Poyang Lake is of good quality and is known as the "last pot of clear water" of the Yangtze River Basin in China. In this paper, the reasons of "last pot of clear water" of Poyang Lake were analysed to demonstrate how economic development and environmental protection can be coordinated. There are three main reasons for contributing to this coordinated development: 1) the unique geomorphologic features of Poyang Lake and the short water residence time; 2) the matching of the basin physical boundary with the administrative boundary; and 3) the implementation of "Mountain-River-Lake Program" (MRL), with the ecosystem concept of "mountain as source, river as connection flow, and lake as storage". In addition, a series of actions have been taken to coordinate development, utilisation, management and protection in the Poyang Lake basin. Our key experiences are: considering all basin components when focusing on lake environment protection is a guiding principle; raising the living standard of people through implementation of various eco-economic projects or models in the basin is the most important strategy; preventing soil and water erosion is critical for protecting water sources; and establishing an effective governance mechanism for basin management is essential. This successful, large-scale basin management model can be extended to any basin or lake regions of developing countries where both environmental protection and economic development are needed and coordinated.     

近 40 年来窟野河流域土地利用类型变化及驱动因素

为分析土地利用变化的内部特征及驱动机制,从土地利用整体格局、土地利用转移方向、转移程度和土地利用单一动态度方面出发,全面分析近40年以来窟野河流域土地利用的时空变化特征,并利用SPSS软件系统地阐述了其驱动机制。主要结果表明:目前,该流域各土地类型面积占比为草地耕地煤矿用地林地沙地居住用地水域未利用土地,耕地主要分布在研究区中部和东南部,煤矿用地主要分布在河流沿岸;在研究时段内,煤矿用地作为动态度最高的土地利用类型,其面积大幅增加,主要流入源为草地和耕地,该流域煤炭的大规模开采已严重影响到该流域的植被覆盖情况以及农业生产活动;经济的高速发展,尤其是第二、第三产业的壮大是导致该流域煤矿用地和居住用地发生明显变化最主要的驱动因子,而耕地、林地、草地和水域的面积变化也与其息息相关,但变化幅度相对较小;此外,人口作为重要因素之一,也在土地利用的变化过程中起到了较为明显的推动作用。     

基于GIS的抚仙湖流域土地利用时空变化研究

高原湖泊是流域内生产生活的重要水源地,维系着当地经济社会的发展,对于调节气候和美化环境起着不可替代的重要作用。由于城镇化的推进和旅游产业的发展,湖泊流域空间格局发生变化,高原湖泊环境污染加剧。以云南省抚仙湖流域为研究对象,运用GIS空间分析技术和数理统计方法,基于2005～2015年3期遥感影像从土地利用幅度变化、土地利用转移类型和土地利用动态度3个方面分析了流域10 a来土地利用时空变化特征。结果表明:①抚仙湖流域土地利用类型以湖泊水面、有林地、旱地、水田和草地为主,水田、有林地和建设用地面积增长,旱地、草地和灌木林地面积减少,园地、湖泊水面和未利用地面积先增后减,水库坑塘先减后增;②土地利用转换类型以农用地向建设用地转移、耕地内部转移和耕地向林地转移3类为主;③不同时期不同地类不同区域的土地利用动态度存在较大差异,2010～2015年与2005～2010年相比,变化更为剧烈,其他建设用地动态度最高,湖泊水面动态度最低,动态度较高的区域分布于湖泊北岸以及西岸中部,而流域北部边缘、西部边缘的动态度较低。研究成果可为该流域生态环境的保护和土地资源的可持续利用提供理论参考。     

Temporal and spatial dynamics of surface run‐off from Lake Basaka catchment (Ethiopia) using SCS‐CN model coupled with remote sensing and GIS

The Lake Basaka catchment (Ethiopia) has undergone a significant land use–land cover (LULC) change and lake level rise over the past five decades. Significant quantities of water and sediment flow annually into the lake through erosion processes. An appropriate method of estimating the surface run‐off from such ungauged and dynamic catchment is extremely important for delineating sensitive areas (based on run‐off responses) to be protected and for development of suitable measures to reduce run‐off and associated soil loss. Reliable prediction of run‐off, however, is very difficult and time‐consuming for catchments such as that of Lake Basaka. The present study estimated the dynamics of surface (direct) run‐off using the NRCS‐CN model in ArcGIS, assisted by remote sensing and ancillary data. The results indicated the Lake Basaka catchment experienced significant temporal and spatial variability in its run‐off responses, depending on the rainfall (amount and distribution) pattern and LULC changes. A significant run‐off increase occurred after 1973, consistent with significant LULC changes and lake level increments occurring after that period. A reduced vegetation cover also resulted in increased run‐off coefficient of the lake catchment from 0.11 in the 1970s to 0.23 in the 2000s, indicating the important need to consider possible future LULC evolution when forecasting the lake catchment run‐off behaviour.     

泾河流域土地利用/覆被变化对径流情势的影响

通过建立泾河流域SWAT分布式水文模型,重点模拟分析了河流径流情势对土地利用/覆被变化的响应,对比了不同气候条件及人类活动综合影响下研究区水文过程的变化。结果表明:1996年以前土地利用/覆被变化是影响水文过程的主要人类活动影响源,径流量年际变化平稳,属有小幅增加的正偏;年内影响以枯水季节为主,年内分配更趋均匀,径流集中度降低,集中期略有滞后,且趋于平稳;土地利用/覆被变化导致流域蒸散发量、冠层和落叶层截留量减小,入渗量增加,河川基流量和地表径流量相应增大,并在时域上耦合形成了水文过程的新变化;1996年以后,气候条件驱动下泾河年径流量呈现明显的增大趋势,人类活动亦从以土地利用/覆被变化为主转变为以人类水事活动为主的综合影响模式,且人类水事活动超过气候变化和土地利用/覆被变化成为影响水文过程变化的主因。     

Management issues in the Lake Titicaca and Lake Poopo system: Importance of developing a water budget

Lake Titicaca is the largest freshwater lake in South America and the highest of the world’s large lakes. The Desaguadero River links Lake Titicaca to lakes Urur Uru and Poopo and, in wet years to the Coipasa Salt Marsh. Lake Titicaca is bordered by both Bolivia and Peru. The main international lake management problem for the Lake Titicaca/Desaguadero River/Lake Poopo system involves the use of water resources. The maximum usable flow in the Titicaca basin (only 20–25 m³ s^–1), is dramatically less than the estimated demand. Water transfer and irrigation projects will have to be strictly prioritized on the basis of environmental, social, economic and hydrological criteria. Establishing the overall volume and demand for water in the Titicaca system has been critical to making good management decisions. Agreements for the study and management of Lake Titicaca between Peru and Bolivia date back to 1955 when both countries signed a document declaring ‘the indivisible and exclusive joint ownership of both countries of the waters of the lake’. Over time, the two countries agreed to create a Binational Autonomous Authority that would have full autonomy for Titicaca–Desaguadero/Poopo system decisions related to implementing the master plan that they had developed. Although it is hard to quantify conservation success in large lake regions, water use projects are being prioritized, city wastewater pollution in the Bay of Puno is being reduced and ameliorated and a large biodiversity project through the Global Environment Facility is underway.     

A Comparison of Lake Trout Spawning,Fry Emergence,and Habitat Use in Lakes Michigan,Huron, and Champlain

Restoration of self-sustaining populations of lake trout is underway in all of the Great Lakes and Lake Champlain, but restoration has only been achieved in Lake Superior and in Parry Sound, Lake Huron. We evaluated progress toward restoration by comparing spawning habitat availability, spawner abundance, egg and fry density, and egg survival in Parry Sound in Lake Huron, in Lake Michigan, and in Lake Champlain in 2000–2003. Divers surveyed and assessed abundance of spawners at 5 to 15 sites in each lake. Spawning adults were sampled using standardized gill nets, eggs were sampled using egg bags, and fry were sampled using emergent fry traps and egg bags left on spawning reefs overwinter. Spawning habitat was abundant in each lake. Adult lake trout abundance was low in Lake Michigan and Parry Sound, and very high at one site in Lake Champlain. Egg deposition was lowest in Lake Michigan (0.4–154.5 eggs•m⁻², median = 1.7), intermediate in Parry Sound (39–1,027 eggs•m⁻², median = 278), and highest in Lake Champlain (0.001–9,623 eggs•m⁻², median = 652). Fry collections in fry traps followed the same trend: no fry in Lake Michigan, 0.005–0.06 fry•trap⁻¹ day⁻¹ in Parry Sound, and 0.08–3.6 fry•trap⁻¹ in Lake Champlain. Egg survival to hatch in overwinter egg bags was similar in Lake Michigan (7.6%) and Parry Sound (2.3–8.9%) in 2001–02, and varied in Lake Champlain (0.4–1.1% in 2001–02, and 1.8–18.2 in 2002–03). Lake trout restoration appears unlikely in northern Lake Michigan at current adult densities, and failure of restoration in Lake Champlain suggests that there are sources of high mortality that occur after fry emergence.