Landsat ETM Images Research Articles

Assessment of groundwater resources from geophysical and remote sensing data in a basement complex environment using fuzzy-topsis algorithm

This study addresses the pressing global water challenge by focusing on a typical basement complex area experiencing acute water shortage. Indiscriminate well siting without reliable hydrogeological maps has resulted in failed attempts to address water shortages. To overcome these challenges, this research aims to enhance the accuracy and reliability of groundwater potential assessments by incorporating crucial groundwater-related factors.The Fuzzy Technique for Order Preference by Similarity to Ideal Solution (FTOPSIS) method was adopted due to its ability to improve multi-criteria decision-making (MCDM) techniques for effective groundwater resource management. Unlike TOPSIS, FTOPSIS better reflects decision-makers' intentions, especially concerning geological boundaries and natural phenomena. To achieve the objectives of the study, geophysical and remote sensing datasets were utilized. The study employed the electrical resistivity method, utilising the Vertical Electrical Sounding (VES) technique with the Schlumberger array while the remote sensing data used were the Digital Elevation Model (DEM) image and Landsat ETM image which were processed to generate key groundwater conditioning factors. These factors were integrated using the FTOPSIS algorithm. This algorithm facilitated the calculation of the groundwater potential indices by assigning weights based on their level of significance to influencing groundwater potential in order to generate the groundwater potential map (GPM). The GPM was classified into five zones of varying groundwater potential, with very low and low potential occupying 74 % of the total area. Validation with well data yielded an impressive 79 % accuracy, showcasing the model's enhanced precision. Beyond improved accuracy, the study's implications extend to practical applications in groundwater resource management. By providing a clearer understanding of groundwater potentiality, the research can inform more robust decision-making frameworks, promoting sustainable water use not only in the study area but also in similar geological settings of the world.

Automated geometric precise correction of medium remote sensing images based on ASTER global digital elevation model

Accurate and unified information from the increasingly remote sensing (RS) scenes is important for RS applications in multi-sectoral association services of natural resource management. However, these applications in mountain areas are limited by the challenging issues of random geometric distortions and erroneous spatial associations. The paper introduces digital elevation model (DEM) maps as a unified geographic reference to search and match homonymy ground points (HGPs). The proposed computer-based procedure was tested with Landsat TM, ETM and HJ-1B satellite images using ASTER global DEM in the Longitudinal Rang-gorge Valley Region of Southwest China. 1322, 3551 and 694 pairs of HGPs were identified and acquired the geometric accuracies with 43 m (TM), 14 m (ETM) and 123 m (HJ), respectively. The deviations are significantly reduced and the disjoint ground objects are matched. The study satisfies the application requirement of multispectral satellite imagery with less labour and time costs.

Presenting the Spatio-Temporal Model for Predicting and Determining Permissible Land Use Changes Based on Drinking Water Quality Standards: A Case Study of Northern Iran

Quantifying the effect of non-point source pollution from different land use types (e.g., agricultural lands, pastures, orchards, and urban areas) on stream water quality is critical in determining the extent and type of land use. The relationship between surface water quality as the primary source of drinking water and land use patterns in suburban areas with an accelerated pace of industrial development and progressive growth of population has drawn much attention recently. This study aims to determine the type and portion of the land use changes over three-time intervals from 2000 to 2015 in the Jajrood River Catchment (Tehran metropolis, north of Iran). We used satellite images of Landsat TM and ETM for 2005, 2010, and 2015 to analyze land use changes as a spatiotemporal model. According to the image processing and analysis, we classified the land uses of the study area into irrigated farming, orchards, pastures, and residential areas. In addition, we used temporal data from sampling stations to identify the relationship between land use and water quality based on a multivariate regression model. The analysis shows a significant correlation between the type and extent of land use and water quality parameters, including pH, Na+, Ca+, Mg+, Cl−, SO42−, NO3−, and TDS. Pastures and residential areas had the highest impact on water quality parameters among all land use types. Besides, we have used the regression analysis results to determine the maximum permissible areas of each land use type. Consequently, effective management strategies such as land use optimization in catchment scale for this catchment and similar areas will help to consciously protect and manage the quality of drinking water resources.

Natural Radioactivity and Radiological Implications of Stream Sediments at Wadi Aidib Area, South Eastern Desert, Egypt

Wadi Aidib lies at the extreme southern part of the Eastern Desert, Egypt, between 22o15'- 22o21' N and Longitudes 36o20'-36o30' E. Landsat ETM+ false color composite image (bands 3, 2, 1) was used for regional discrimination for different rock types and provide an excellent base map for the study area, morphological features of the stream deposits of the study area were known from Landsat ETM images, in addition to several field observations. The studied stream sediments accumulate in the form of alluvial fans. They are mainly composed of sands, gravels, boulders and contain some heavy valuable minerals which are derived from metavolcanics, metasediments, quartz diorite, biotite and alkali feldspar granites. Heavy liquid separation and magnetic separation techniques in addition to microscopic examination for the studied stream sediment samples were applied to identify the heavy minerals in these sediments. These minerals are represented by magnetite, ilmenite, rutile, garnet, zircon, monazite and Green silicates. The distribution of some elements in the study area is clear that they are concentrated near the outcrops of granites. The radionuclide concentrations were measured in different stations using a calibrated gamma-ray portable detector (RS 230) and the heavy minerals causing radioactivity were separated by heavy liquids and determined by binuclear and environmental scanning electron microscopes. Uranium ranges between 5.25 and 32.05 ppm with an average of 16.63 ppm, Th between 4.4 and 17 ppm with 11.34 ppm as an average and potassium fall between 1.8 and 5.15% with an average of 3.4 %. Correlation between soil radioactivity and its mineralogical content indicate that the high radionuclides contents are mainly attributed to the presence monazite which is the principal source of both uranium and thorium. Uranium high concentrations could be related to the metamict zircon. Absorbed Dose Rate (D), annual effective dose equivalent radium equivalent activity, external and internal hazard index, in addition to activity gamma index caused by gamma emitting natural radionuclide are determined from the obtained values of 238U, 232Th and 40K. Fairly, some of the studied stations do not satisfy the universal standards. 40K plays the main and most important role in dose rate contribution.

EXTENT OF URBANIZATION IMPACT ON FOREST RESOURCES IN OJU LOCAL GOVERNMENT AREA, BENUE STATE, NIGERIA

Several researches have been carried out on urbanization especially urban areas in Nigeria and globally, but were mostly centred on major cities and little has been done on the growth of smaller towns. This study was carry out to determine the impact of urbanization on forest resources of Oju local Government Areas of Benue State, Nigeria.. Specifically the study determined the extent and growth rate of urban areas and their impacts on forest resources in Oju local Government Area of Benue State, Nigeria. Remotely sensed images of Landsat TM and ETM+ were acquired for 1998 and 2008 while Operational Landsat Imager (OLI) was used for 2018 respectively. The images were subjected to various image processing techniques and a supervised classification using Maximum Likelihood Classifier was performed in Integrated Land and Water Information System (ILWIS) software. The classification resulted in five classes of Land use and Land cover (LULC) of forested areas, farmland, vegetation, built-up areas and water. The results shows that between 1998 and 2018 forest decreased by -231.5.km2 (63.24%) representing an annual rate of -3.16%. The built-up area increased by 150.45km2 (108.99%) at an annual rate of change of 5.45% Farmland area decreased by -30.56 km2 (-6.5%) at an annual growth rate of 0.32%. The study revealed that, loss of naturally vegetated areas was mainly as a results of urban growth and expansion, farming and logging activities with commercial activities. The study recommends awareness creation against deforestation and encouragement of community and urban forestry.

Presenting the spatial-temporal model for assessing and predicting qualitative changes of the groundwater resources in Shahriar, Tehran, Iran.

The quality of surface and groundwater are fundamental concerns. The World Health Organization (WHO) reports that 80% of diseases are waterborne. This percentage mostly lies in developing nations and underdeveloped countries. Determining the relationship between land-use patterns and groundwater quality changes is one of the methods to evaluate the impact of land-use on the hydrological condition of each region which ultimately assists in managing natural resources. In the present study, the spatial-temporal model via satellite images of Landsat TM, ETM, and OLI for2002, 2007, 2012, and 2017 are used to investigate all these modalities in Shahriar Plain, Tehran, Iran. Following image processing and analysis, the land-uses of the study area are classified into urban, farming, and bare lands. In order to assess the water quality of the study area, the periodic sampling data of piezometric wells in the plain were used from 2002 to 2017. Based on the US Salinity Laboratory (USSL) diagram, water qualities for agricultural uses are classified. Results demonstrated that land area has changed over time indicating an increase in urban land area and declines in agricultural and bare lands. Additionally, the results of the groundwater quality indicated C3S1 class in the second and third periods have increased to 3.58% (1025.93ha) and 12.82% (9367.85ha) while C2S1 class has been decreased in second and third periods to 3.58 and 12.82%. C1S1 and C4S1 classes during the three periods have been 0.

Applying various satellite image processing methods on Aster and Landsat ETM+ data to identify and separate the alteration zones around gold mine of Akhtarchi, Khomein, Iran

The study area is located 100 km southeast of Arak and in two structural zones of Central Iran in the north and Sanandaj-Sirjan in the southern part. Regarding its geological structures, the area has become the source of important mines including the Akhtarchi gold mine, Aliabad iron mine, Ochestan feldspar mine, and Dali gold and copper mines. Therefore, promising areas for exploration activities are identified using the analysis of satellite images of ASTER and Landsat ETM + in the region to identify alteration areas. For this purpose, the necessary corrections were applied to the satellite images. Then, to identify the alteration parts related to the gold deposits, different satellite image processing methods of ETM + and ASTER were used. These methods include making a false-color composite, band ratio, Selective Principal Components Analysis (SPCA), Spectral Angle Mapper (SAM) method, Spectral Information Divergence Classification (SID), Endmember Collection Dialog Components (ECDC), and innovative methods such as Principal Component Analysis (PCA) and Spectral Angle Mapper, as well as unsupervised classification methods. In the end, the major alterations in the region were observed. In the obtained images, the prophylitic zone and the phyllic and argillic zones in the region were observed. To introduce the optimal method, the results of the various methods mentioned were compared with each other and with the current situation of the mines. The alteration zones were identified through band ratio and SAM methods and the combined methods with more power. Finally, SAM, 2:1 ratio, and the combined methods were identified as successful methods for more accurate separation of the alteration zones.

Análisis de cambio en la cobertura vegetal y uso del suelo en la región centro-norte de México. El caso de la cuenca baja del río Nazas

Leija, E.G., Valenzuela-Ceballos, S.I., Valencia-Castro, M., Jiménez-González, G., Castañeda-Gaytán, G., Reyes-Hernández, H., Mendoza, M.E. 2020. Analysis of change in vegetation cover and land use in the north-central region of Mexico. The case of the lower basin of the Nazas river. Ecosistemas 29(1): 1826. https://doi.org/10.7818/ECOS.1826 Deforestation has an important impact on ecosystems, altering their capacity for providing environmental services, affecting particularly semiarid areas. The Parque Estatal Cañón de Fernández is located on the lower section of Nazas river, with 24936,6 ha and constitutes an important national and international natural protected area, because it supplies water to several cities in the north of Mexico and is recognized as a highly important habitat for aquatic birds. Nevertheless, the necessity of satisfying agricultural activities and a growing population has promoted land use and cover changes in the region. The aim of this research was to evaluate land cover and land use changes on the lower basin of Río Nazas between 1990 and 2016. Based on visual interpretation of Landsat Tm and ETM images we generated digital data bases for land cover and land use. On 2016 the natural vegetation was composed by xeric shrub and riparian forest. In twenty six years deforestation affected 32.1% of the total area. There is a necessity to develop public policies for improving water sustainable use to preserve this xeric ecosystem.

Ecotourism site suitability evaluation using geospatial technologies: a case of Andiracha district, Ethiopia

This study is aimed to identify potential ecotourism sites using Geographic Information System and Multi-criteria Decision Analysis in Adiracha district of Sheka Zone, south-western Ethiopia. Landsat ETM Image and STRM data of 2016 with 30 m resolution and topographic map of Ethiopia were used in this study. Ecotourism potential site selection criteria were designed based on 26 stakeholder’s opinions. The final suitability map of ecotourism has been realized by applying an integrated weighted overlay technique of Geographic Information System. The suitability map was categorized into four classes as Suitable, Moderately Suitable, Less Suitable, and Not Suitable. The study attempts to indicate the level of ecotourism suitability at different location in the study area. The outcome of this research is useful to understand the spatial information of Sheka district that can be used for policy makers. This study can be also used as a basis for assessing ecotourism site suitability in other regions.

Drought Risk Assessment in the Khushab Region of Pakistan Using Satellite Remote Sensing and Geospatial Methods

Drought is a harmful and slow natural phenomenon that has significant effects on the economy, social life,agriculture and environment of the country. Due to its slow process it is difficult to study this phenomenon. RemoteSensing and GIS tools play a key role in studying different hazards like droughts. The main objective of the study wasto investigate drought risk by using GIS and Remote Sensing techniques in district Khushab, Pakistan. Landsat ETMimages for the year 2003, 2009 and 2015 were utilized for spatial and temporal analysis of agricultural andmeteorological drought. Normalized difference vegetation index (NDVI) Standardized Precipitation Index (SPI) andrainfall anomaly indices were calculated to identify the drought prone areas in the study area. To monitormeteorological drought SPI values were used and NDVI was calculated for agricultural drought. These indices wereintegrated to compute the spatial and temporal drought maps. Three zones; no drought, slight drought and moderatedrought were identified. Final drought map shows that 30.21% of the area faces moderate drought, 28.36% faces slightdrought while nearly 41.3% faces no drought situation. Drought prevalence and severity is present more in the southernpart of Khushab district than the northern part. Most of the northern part is not under any type of drought. Thus, anoverall outcome of this study shows that risk areas can be assessed appropriately by integration of various data sourcesand thereby management plans can be prepared to deal with the hazard.

Drought Risk Assessment in the Khushab Region of Pakistan Using Satellite Remote Sensing and Geospatial Methods

Drought is a harmful and slow natural phenomenon that has significant effects on the economy, social life,agriculture and environment of the country. Due to its slow process it is difficult to study this phenomenon. RemoteSensing and GIS tools play a key role in studying different hazards like droughts. The main objective of the study wasto investigate drought risk by using GIS and Remote Sensing techniques in district Khushab, Pakistan. Landsat ETMimages for the year 2003, 2009 and 2015 were utilized for spatial and temporal analysis of agricultural andmeteorological drought. Normalized difference vegetation index (NDVI) Standardized Precipitation Index (SPI) andrainfall anomaly indices were calculated to identify the drought prone areas in the study area. To monitormeteorological drought SPI values were used and NDVI was calculated for agricultural drought. These indices wereintegrated to compute the spatial and temporal drought maps. Three zones; no drought, slight drought and moderatedrought were identified. Final drought map shows that 30.21% of the area faces moderate drought, 28.36% faces slightdrought while nearly 41.3% faces no drought situation. Drought prevalence and severity is present more in the southernpart of Khushab district than the northern part. Most of the northern part is not under any type of drought. Thus, anoverall outcome of this study shows that risk areas can be assessed appropriately by integration of various data sourcesand thereby management plans can be prepared to deal with the hazard.

English

Satellite remote sensing has contributed immensely to the interpretation of linear features and other geological structures. In the study area, lineaments mapped were linear and planar features on satellite imageries that are expression of fractures, or faults within the subsurface.  Image lines of different contrast may extend from a few centimetres to several of metres in length. The Landsat imagery used has a spatial resolution of 30 x 30 m, and eleven spectral bands covering the visible and thermal region of electromagnetic spectrum. Four spectral bands were selected and used for the purpose of structural mapping namely; thermal infra-red band (Band 11), 11.5 to 12.51 µm; Short-wave infrared (Band 6), 1.57 – 1.65 µm; near Infrared (Band 5) 0.85 to 0.88 µm and Red (Band 4) 0.64 – 0.67 µm. Lineaments extracted from the digital satellite scene are concentrated mostly on the sandstone belt in the North-East close to Amasiri area. A total of 116 lineaments were generated. Seven thematic maps were produced; digital elevation model (DEM) was used to create surface features maps, shaded relief and slope while the regional lineament map was digitized from the enhanced colour composites of Landsat ETM (bands 7, 5 and 2) image using ARCGIS 10.0 software for visual extraction and delineation of geological structures which were also ground-truth. The area indicates major NE – SW to minor E – W orientation of lineaments. The lineament density identified indicates regional lineaments are of great importance as indexes for groundwater exploration, mineralization targets, rocks quarrying and structural interpretation.  Key words: Landsat imagery, geological structures, linear trends, ground-truth, Afikpo area Southeastern Nigeria. &nbsp

Topobathymetric 3D model reconstruction of shallow water bodies through remote sensing, GPS, and bathymetry

Since there are no mathematical models that can calculate the Laguna de Bustillos’ water storage levels, water balance requires this data to understand the connectivity between this water body and the Cuauhtemoc aquifer. This article presents a new three-dimensional reconstruction technique based on a time series of multispectral remote sensing images, bathymetry, a topographic survey with high precision GPS, and regional contours. With the images of Landsat ETM+/OLI and Sentinel 2A from 2012 to 2013, 2016, and 2017, the contours of the water surface were extracted using the MNDWI and were associated with an elevation received from GPS. An Autonomous Surface Vehicle was also used to obtain the bathymetry of the lake. A topographic survey was carried out using GPS in populated areas, and the contour lines extracted from the INEGI Continuous Elevations Model 3.0. A DEM was constructed using ArcGIS 10.5.1, and surfaces and volumes were calculated at different elevations and compared with 16 Landsat TM/ETM+/OLI multispectral images from 1999 to 2018. The results showed that the mean of the average intersection area between the test images and the area extracted from the 3D model is above 90.9% according to the confidence interval, kappa overall accuracy 95.2–99.7 %, and a coefficient 89.9–99.3 %. This model proved to be very accurate on a regional scale when the water level exceeded 1971.32 meters above mean sea level and useful to evaluate and administer water resources. DOI: https://doi.org/10.54167/tch.v12i1.129

Detection of Land Cover Changes using Landsat ETM Images at Mendanau North Coastal and Batu Dinding Island in Selat Nasik District, Belitung Regency

Land cover changes is a physical impact which caused by the the existence of human activity that is quite high in parts of the lithosphere of the earth. The change in landscape certainly has a positive correlation with the dynamics of land use in an area, so that regular monitoring needs to be done, because often land use occurs out of control and not even in accordance with its designation. The main problems that occur in Mendanau Isalnd and Batu Dinding Island are the high level of utilization of mangrove ecosystems, the conversion of mangrove land into ecotourism areas, ports area, residental area and mining area (bauxite). This study aims to monitor changes in land cover in the northern coastal areas of Mendanau Island and Batu Dinding Island in Belitung Regency for 6 years (2000, 2002, and 2006) using a remote sensing technology approach, where image data processing refers to a guided classification method combined with check the field. The satellite images used are still classified as low resolution, namely Multitemporal ETM satellite images with ± 10% cloud cover rate. The results showed that, found 6 land cover classes, namely settlement, open land, mangrove vegetation, non-mangrove vegetation, marine waters, and clouds, which can be detected there has been a change in the increase in the area of non-mangrove vegetation by 365.47 ha, while residential areas experienced fluctuating conditions, namely an increase in cover area in 2000-2002 around 111.94 ha, then declined again in 2006 amounting to 61.28 ha. Unlike the case with the area of open land cover and cover of mangrove vegetation which tends to decrease. The area of open land cover in 2000-2002 decreased by 16.96 ha, then declined again in 2006 by 32.32 ha. The cover area of mangrove vegetation in 2000-2002 decreased by 69.5 ha, then decreased again in 2016 amounting to 208.82 ha.

Land Use Change using Geospatial Techniques: The Case of AwojaWatershed in Ngora District in Eastern Uganda

This study used remote sensing and Geo-graphical Information System (GIS) to assess the status of Awoja watersheds in Ngora district of Eastern Uganda. Landsat ETM Images covering the whole of Ngora district and part of Lake Kyoga of two time periods was carried out in the period April to July 2015. This wasacquired using USGS Earth Explorer. The images were processed and enhanced with ERDAS 2014 software to aid information extraction and analysis. Land cover change analysis was performed using ENVI 5.3 software. Supervised classification method with maximum likelihood algorithm was performed to obtain land use/ cover types. Five land use/cover types were identified: open water, wetland, tree cover, agriculture and built up area. The findings indicate a fivefold increase in built up area by 154.27km2 (i.e. 375%) and open water increased by 8.7 km2 (i.e. 55.33%). Wetland, tree cover and agriculture reduced in area by -1.0km2 (i.e. 5.1%), - 48.07 km2 (i.e. 34.46%) and -114.0km2 (i.e. 51.05%), respectively. These changes mainly resulted from deforestation, wetland encroachment, poor attitude and over population. Unless, appropriate watershed restoration strategies are designed through afforestation, law enforcement on culprits, continuous sensitisation of the watershed community on the causes of degradation, the over 1,700,000 individuals whose livelihoods depend on Awojawill continue to suffer the effects of degradation. There is need to advocate for non-consumptive projects as alternative sources of income. Keywords: Remote sensing, GIS, Watersheds.

The evolution of landscape ecological security in Beijing under the influence of different policies in recent decades

Urbanization is an important force driving the development of the social, economic, and ecological environments in urban China. As the capital of China, Beijing has experienced a shift in the development process from emphasizing economic development to emphasizing ecological livability in recent decades. During this period, the Olympic Games, real estate development, and environmentally friendly construction policies were major events that affected Beijing's urban ecosystem and its safety. Based on the Pressure–State–Response (P-S-R) framework model, this paper establishes an indicator system for assessing the ecological security of Beijing from 1995 to 2015. The indicators were generated through coupling of an ecological model with time-series multi-source remote sensing data such as night light images and Landsat ETM images. We assessed ecological security during different policy periods and developed an ecological security early warning system for Beijing. After the effects of the economic development policy and the bid for the Olympic Games from 1995 to 2005, the urban area of Beijing with falling ecological security continues to expand. From 2005 to 2010, due to the joint effect of 2008 Olympic venue construction, urban environmental remediation policies, and real estate policies, the overall safety level in the central city was better, but the suburbs showed the opposite trend. In 2010–2015, real estate developed explosively in Beijing, while environmentally friendly development became strongly emphasized and the economic status of the capital weakened. The ecological security of the main urban area began to improve significantly, but the outer urban area and suburban areas were greatly affected by real estate development and exhibited a clear decline in ecological security.

MONITORING CHANGES OF ECOSYSTEM SERVICES SUPPLY AND DEMAND PATTERN IN CENTRAL AND SOUTHERN LIAONING URBAN AGGLOMERATIONS, CHINA USING LANDSAT IMAGES

Abstract. Indentifying the spatio-temporal patterns of ecosystem services supply and demand and the driving forces is of great significance to the regional ecological security and sustainable socio-economic development. Due to long term and high-intensity development, the ecological environment in central and southern Liaoning urban agglomerations has been greatly destroyed thereafter has restricted sustainable development in this region. Based on Landsat ETM and OLI images, land use of this urban agglomeration in 2005, 2010 and 2015 was extracted. The integrative index of multiple-ecosystem services (IMES) was used to quantify the supply (IMESs), demand (IMESd) and balance (IMESb) of multiple-ecosystem services, The spatial patterns of ecosystem services and its dynamics for the period of 2005–2015 were revealed. The multiple regression and stepwise regression analysis were used to explore relationships between ecosystem services and socioeconomic factors. The results showed that the IMESs of the region increased by 2.93 %, whereas IMESd dropped 38 %. The undersupplied area was reduced to 2. The IMESs and IMESb were mainly negatively correlated with gross domestic product (GDP), population density, foreign investment and industrial output, while GDP per capita and the number of teachers had significant positive impacts on ecosystem services supply. The positive correlation between IMESd and GDP, population density and foreign investment were found. The ecosystem services models were established. Supply and balance of multiple-ecosystem services were positively correlated with population density, but the demand was the opposite. The results can provide some reference value for the coordinately economic and ecological development in the study area.

Change Detection and Prediction of Urmia Lake and its Surrounding Environment During the Past 60 Years Applying Geobased Remote Sensing Analysis

Abstract. The gradual depletion of Urmia lake has been a challenge in both national and international scale during recent years. In recent decades the imprudent industrial development accompanied by continuous use of groundwater aquifers has been one of the most pivotal reasons for this crisis. Water level monitoring and detection of its changes within Urmia lake as well as the surrounding environment in the past 60 years integrating GIS, Remote sensing and photogrammetric methods is the main goal for this study. In order to accomplish this, Aerial Photogrammetry images and derived topographic maps from them for the year 1955, Digital Elevation data, quantitative and qualitative information regarding water wells and lake Urmia respectively and finally remotely sensed images of Landsat TM, ETM+ and OLI sensors were used. The temporal range for the study was set to 60 from the year 1955 to 2014. Scrutinizing 12 images relating to different periods, vast changes in both area and perimeter of the lake were detected. Based on the results, the lake area has decreased from 451800 hectares in 1955 to 89730 in recent years due to various causative factors. It is also found that the highest water recession, which caused increasing coastal salty areas, has been occurred in the southern parts of the lake. While the receding water level of the lake has a deep correlation with the increasing agricultural activities around the lake, it has a reverse relation with the lake water EC. These fluctuations can be detrimental to the environment, economy and society. Looking at the changes in lake Urmia, if the current situation keeps on and no drastic measures are taken, turning into a salt land, the Lake would be completely disappeared till 2033.

Assessing Land Use and Land Cover Changes in the Murchison Bay Catchment of Lake Victoria Basin in Uganda

The Murchison Bay catchment in the northern shoreline of Lake Victoria basin is a high valued ecosystem because of the numerous human-related activities it supports in Uganda. The catchment has undergone tremendous human-induced land use/cover changes, which have not been quantified. This study aimed at quantifying the land use/cover changes as well as the rate at which these changes occurred over the last three decades in the catchment. This was achieved using remote sensing techniques and Geographic Information System (GIS) to analyse and contextualize the changes. To that effect, images of Landsat satellites MSS, TM, ETM+ and OLI were interpreted using supervised image classification technique to determine the land use/land cover changes from 1984 to 2015. The obtained results indicated that the catchment has undergone huge land use and land cover transformations over the last three decades attributable to rapid population growth and urbanization. The prevailing changes in footprint between 1984 and 2015 were expansions of built–up land (20.58% to 49.59%) and open water bodies (not detected in 1984 to 1.74%), and decreases in the following sectors: agricultural lands (from 43.88% to 26.10%), forestland (from 23.78% to 17.49%), and wetlands (from 11.76% to 5.08%). The changes pose a threat to the environment and water quality of the Murchison Bay and consequently increases National Water and Sewerage Corporation water treatment costs. Therefore, there is the need to take critical and practical measures to regulate and police land use, water use rights and conserve the environment especially wetlands.

Comparing the capability of ETM+ and LISS-iii imagery in riparian forest mapping: a case study of Maroon river, Iran.

In order to assess and compare the capability of ETM+ and LISS-III data in the mapping of riparian forests of the Maroon River in Behbahan, Iran, a small window of panchromatic and multispectral images of LandsatETM+ and IRS-1D-LISS-III satellite data was selected. The quality of data and radiometric error was checked and geometric correction was implemented using 25 ground control points. Principal component analysis (PCA), tasseled cap transformation and appropriate vegetation indexes (NDVI) were applied to provide the main bands for incorporation in the classification processes. The study also used image fusion by Pansharp (the Gram-Schmidt Spectral Sharpening method) and the HSV method for high spectral and spatial resolution. After selecting the training data, the classification was carried out by choosing seven-class and three-class land-use/cover using a maximum likelihood algorithm. Transformed divergence and Jeffreys–Matusita were used to test the separability of the classes. Considering the results, it can be concluded that IRS1D-LISS-III and landsat 7-ETM+ data have a suitable ability for mapping the Maroon riparian forest as well as the classification of forest to separate landuse. The classification using original bands of ETM+ is better than LISS-III data due to higher spectral resolution. The opposite of these results is only shown in the classification with three user classes. The overall accuracy and kappa coefficient in this method were 98.80 and 0.84, respectively.