Landsat

Extraction of water bodies from satellite imagery has been broadly explored in the current decade.  So many techniques were involved in detecting of the surface water bodies from satellite data. To detect and extracting of surface water body changes in Nagarjuna Sagar Reservoir, Andhra Pradesh from the period 1989 to 2017, were calculated using Landsat-5 TM, and Landsat-8 OLI data. Unsupervised classification and spectral water indexing methods, including the Normalized Difference Vegetation Index (NDVI), Normalized Difference Moisture Index (NDMI), Normalized Difference Water Index (NDWI), and Modified Normalized Difference Water Index (MNDWI), were used to detect and extraction of the surface water body from satellite data. Instead of all index methods, the MNDWI was performed better results.  The Reservoir water area was extracted using spectral water indexing methods (NDVI, NDWI, MNDWI, and NDMI) in 1989, 1997, 2007, and 2017. The shoreline shrunk in the twenty-eight-year duration of images.  The Reservoir Nagarjuna Sagar lost nearly around one-fourth of its surface water area compared to 1989. However, the Reservoir has a critical position in recent years due to changes in surface water and getting higher mud and sand. Maximum water surface area of the Reservoir will lose if such decreasing tendency follows continuously.

Abstract
In this study the relationships between vegetation  regeneration dynamics to topography and burn severity for a Canadian landscape were investigated using freely available Earth Observation (EO) imagery from Landsat TM sensor. The Okanagan Mountain Park, located in the Montane Cordillera Ecozones of Western Canada at which a fire occurred in 2003, was used as a case study. First, vegetation regeneration dynamics were quantified for a period of 8 years following the fire event based on a chronosequence analysis of the Normalized Difference Vegetation Index (NDVI) and the Regeneration Index (RI). The spatio-temporal patterns of post-fire NDVI from each image date were statistically compared to
the pre-fire pattern to determine the extent to which the pre-fire spatial pattern was re-established and also the rate of recovery. Subsequently, the relationships of vegetation regrowth to both topography and burn severity was quantified using a series of additional statistical metrics. Burn severity was derived from the differenced Normalized Burn Ratio (dNBR) index computed from the Landsat TM images. Information
on topography properties of the region was obtained from the ASTER global operational product. NDVI and RI analysis indicated a moderate vegetation recovery to pre-fire patterns, with regeneration to over 60% of the pre-fire levels 8-years after the fire. Regression analysis of pre- and post-fire mean
NDVI exhibited significant re-growth in the first 3 years after the fire with a more gradual return in later years (an increase of 0.400 in R2 by 2006 compared to only an increase of 0.129 for the subsequent 5 years). Re-growth rates appeared to be somewhat higher in north-facing slopes in comparison to south
facing ones. As expected, NDVI decline due to fire was positively correlated with burn severity class, whereas negative correlation was found between damage and regeneration ability (recovery after 3 years = low severity 64%/high severity 58%, recovery after 8 years = low severity 72%/high severity 70%). To our knowledge, this study is one of the few attempting to explore the interrelationships of post-fire vegetation regrowth, topography and burn severity, especially in the case of a single large fire. RI based on control plots provides a valuable tool to quantify fire impact and subsequent vegetation regrowth. Furthermore, indication of burn severity is useful for strategically rehabilitating areas of slow or unsuitable
post-fire vegetation recovery. This study corroborates the significance of EO technology as a successful and cost-effective solution in providing information related to economic and environmental post-fire regeneration assessment.

The purpose of this thesis is the observation of the over-time changes of the Dead Sea for the years 1972 – 2019, with the utilization of Geographic Information Systems and the use of satellite and other data. Particularly, the problem of the shrinking of the water surface, which is a global environmental problem, is being addressed. The core of the methodology is based on the digitization of the Dead Sea level using satellite imagery, and the utilization of ArcGIS software for the extraction of the results. The satellite images that were used belong to the Landsat Satellite Program of National Aeronautics and Space Administration (NASA). Specifically, false color images were used for the digitization process, which were exported using ArcMap. These images include infrared bands, because water bodies absorb the radiation of these bands, so the boundary between land and water is more distinct. Moreover, in order to help analyze the study area a series of maps was created, such as a geological map, a land cover map and a digital elevation model. Based on the results obtained from the digitization, maps were produced showing the shrinkage of the Dead Sea for the entire study period and for every decade. In conclusion, it turned out that within 47 years the level of the Dead Sea has decreased by 38 meters and its area by 375 km2, which corresponds to a 38% reduction from the original area. It is important to note that the level of the lake continues to decline at a rate of 1 m/year, which negatively affects its environment and requires measures to be taken by the competent authorities.

There is a great demand for accurate and high-resolution seafloor topography (bathymetry) data. However, at present availability of such data remains spatially incomplete and limited. Bathymetry in shallow water areas is challenging for vessel-based bathymetric surveys and this zone is where remote sensing typically outperforms traditional methods such as echo sounding. The obvious advantages over conventional echo sounding methods include the wide data availability, synoptic surface coverage, and improved spatial resolution. Due to the high cost associated with traditional bathymetric surveys, the availability of up-to-date bathymetric charts in developing countries is rare or limited to a few charts for some areas. In this study, a ratio-transform model was applied on Landsat imagery to derive bathymetry at sites in nine rivers and creeks along the Nigerian coastal area. Accuracy tests comparing the image-derived bathymetry with reference data from echo sounding of Lighthouse Creek in Lagos and hydrographic charts of the other sites confirms good agreement at some sampled locations. The results of this study prove that this remote sensing method can augment existing hydrographic datasets in the country and is a useful reconnaissance tool for hydrographic surveying offices. It also offers a viable interim solution for areas where there is inadequate hydrographic data and scarce resources for extensive surveys using other methods.

Seagrass meadows cover about 0.05-0.15% of the world’s ocean and are some of the most productive systems on Earth. Direct and indirect human-derived impacts have led to significant seagrass declines worldwide and the alteration of services linked to their biodiversity. Effective conservation and the provision of sustainable recovery goals for ecologically significant species, such as green turtles (Chelonia mydas), are limited by the absence of reliable information on seagrass extent. This is especially true for the Wider Caribbean Region (WCR) where many conservation initiatives are under way, but impaired by the lack of accurate baseline habitat maps. To assist with such a fundamental conservation need using high resolution remote sensing data, both environmental and methodological challenges need to be tackled. First, the diversity of environments, the heterogeneity of habitats, and the vast extent of the targeted region mean that local expertise and field data are seldom available. Second, large-scale high-resolution mapping requires several hundred Landsat 5 and 7 images, which poses substantial processing problems. The main goal of this study was to test the feasibility of achieving Landsatbased large-scale seagrass mapping with limited ground-truth data and acceptable accuracies. We used the following combination of methods to map seagrasses throughout the WCR: geomorphological segmentation, contextual editing, and supervised classifications. A total of 40 Landsat scenes (path-row) were processed. Three major classes were derived (“dense seagrass”, “medium-sparse seagrass”, and a generic “other” class). Products’ accuracies were assessed against (i) selected in situ data; (ii) patterns detectable with very high-resolution IKONOS images; and (iii) published habitat maps with documented accuracies. Despite variable overall classification accuracies (45-85%), the resulting thematic maps were deemed acceptable to (i) regionally provide, following their critical evaluation, an adequate baseline for further large-scale conservation programs and research actions; and (ii) regionally re-assess carrying capacity estimates for green turtles. They certainly should represent a drastic improvement relative to current regional databases.

NDVI (Normalized Difference Vegetation Index) is easily calculated using the reflectance images of the scene in red and infrared bands. It permits to detect the vegetation areas (forests, grasses, groves, …) as well as to distinguish waters (oceans, seas, lakes, rivers, …) and soils (rocks, buildings, roads, …). Images supplied by Landsat 8 OLI (Operational Land Imager) sensor in the bands 4 and 5 can be used for NDVI calculation, deriving by digital numbers the solar radiation incident on the satellite sensor (Top Of Atmosphere, TOA). This paper is aimed to demonstrate that this transformation can be easily operated in GIS that also permits to implement NDVI formula. Landsat 8 OLI red and near-infrared images of Campania areas around the Gulf of Naples were considered: NDVI was calculated using TOA transformation of the original data. Classification of these data was applied to distinguish three homogeneous classes such as bare soil, water (sea and lakes) and vegetation.

A disponibilidade de água em uma região está relacionada a sua presença em quantidade e qualidade necessárias para atender a demanda da sociedade. Nas últimas décadas, com a in-tensificação do processo de urbanização, a questão do saneamento básico se tornou preocu-pante. Grandes centros urbanos apresentam condições sanitárias precárias e os seus mananciais de abastecimento são afetados pela poluição dos esgotos ou pela perda de capacidade devido ao aumento das vazões de abastecimento. Há a necessidade de construir um planejamento integrado dos recursos hídricos e do saneamento ambiental, levando em consideração as diver-sas questões que influenciam e são influenciadas por esses. Com isso, a bacia hidrográfica foi considerada pelas Políticas Nacionais de Recursos Hídricos de Saneamento Básico como a unidade territorial de planejamento, necessária para o desenvolvimento de políticas públicas para a gestão desses setores. A partir desse contexto, o presente trabalho objetivou determinar e analisar as características fisiográficas das bacias hidrográficas do município de Ananindeua, localizado na Região Metropolitana de Belém (RMB), com o intuito de proporcionar subsídios ao planejamento para gestão dos recursos hídricos e do saneamento ambiental desta cidade. A metodologia aplicada baseou-se em informações de imagens orbitais e modelos digitais de elevação (MDE) para caracterização dos aspectos pretendidos. Dessa forma, os resultados obtidos mostram que a cobertura vegetal vem diminuindo ao longo das últimas décadas; a mata ciliar é inexistente em vários trechos dos cursos d’água; as nascentes encontram-se sobre forte pressão da urbanização; e os parâmetros morfométricos das bacias são fundamentais para estabelecer critérios de planejamento de redes de esgoto e distribuição de água.

The mangrove is one of the most endangered ecosystems on the planet. Indeed, despite all the benefits that it recognizes, namely the reduction of the risk of coastal erosion, the breeding and nursery grounds for fish or the sequestration of carbon, nevertheless are alarming loss of mangrove area in the world. This study focuses on the establishment of a GIS and an analysis of the dynamics and typology of mangroves in Libreville and its surroundings. Landsat high spatial resolution satellite imagery (30 m) mapped the dynamics of mangroves and land cover. As a result, mangroves evolve in crescendo and decrescendo in time and space. The mangrove areas of the selected dates are: 920 km², 1051.2 km², 997.3 km² and 1048.64 km², respectively in 1990, 2000, 2014 and 2018. This change is partly due to the cloudy disturbance of the different images and, above all, the ever-increasing evolution of the built-up space, and therefore human and also industrial pressures. In order to analyze the typology of mangroves in Libreville and its surroundings, three maps were combined (mangrove species, mangrove height and mangrove cover). This analysis is a prerequisite in the study of the estimation of mangrove biomass. The results produced were introduced in a GIS with ArcGis, which itself should be managed by an environmental observatory.

Para realizar o download do Legado Landsat no “site da NASA”, o local da Web formalmente conhecido como Serviço Geológico dos Estados Unidos (U.S.G.S. – United States of Geological Survey), é necessário preencher um formulário de cadastro bem detalhado, porém fundamental para o aperfeiçoamento dos produtos que o portal oferece para a comunidade global.

Pelo menos uma vez ao mês eu visito o site USGS para ter acesso à família Landsat e outros produtos. Os mecanismos para pesquisa de imagens são práticos e intuitivos. Algumas funcionalidades foram abordadas de forma suave através deste tutorial. Um fato que chama atenção no site é o registro obrigatório: para ter acesso ao produto completo para download, o usuário precisa estar cadastrado e logado no site.

Αν και πολλοί γνωρίζουν τη σχέση των Πολεμικών Αεροποριών με το Διάστημα διεθνώς και αρκετοί γνωρίζουν ότι στην Ελλάδα η ΠΑ υπήρξε το πρώτο όπλο από τα τρία, που αντιλήφθηκε από το 1977 την ανάγκη αξιοποίησης του Διαστήματος και συγκρότησε ειδικό φορέα, λίγοι γνωρίζουν την σχέση της Σχολής Ικάρων με αυτό. Με αφορμή την επανέκδοση του ΙΚΑΡΟΥ και την ύπαρξη ειδικής θεματικής του παρόντος τεύχους στο Διάστημα, το κείμενο αυτό θα παρουσιάσει ορισμένα σημεία αυτής της σχέσης.

Lake Urmia, one of the largest saltwater lakes on earth and a highly endangered ecosystem, is on the brink of a major environmental disaster similar to the catastrophic death of the Aral Sea. With a new composite of multi-spectral high resolution satellite observations, we show that the area of this Iranian lake has decreased by around 88% in the past decades, far more than previously reported (~ 25% to 50%). The lake's shoreline has been receding severely with no sign of recovery, which has been partly blamed on prolonged droughts. We use the lake basin's satellite-based gauge-adjusted climate record of the Standardized Precipitation Index data to demonstrate that the on-going shoreline retreat is not solely an artifact of prolonged droughts alone. Drastic changes to lake health are primarily consequences of aggressive regional water resources development plans, intensive agricultural activities, anthropogenic changes to the system, and upstream competition over water. This commentary is a call for action to both develop sustainable restoration ideas and to put new visions and strategies into practice before Lake Urmia falls victim to the Aral Sea syndrome.

La cobertura boscosa de ecosistemas templados que se distribuye en el territorio mexicano, constituye un importante sumidero de carbono, hecho que tiene como potencial la disminución de efectos adversos que contribuyan negativamente al cambio climático. El estado de Durango presenta una amplia extensión de bosque templado, por lo cual es el principal productor forestal maderable de la república mexicana, actividad relevante en la gestión de los recursos forestales que contribuyen a la captura de carbono. Los objetivos planteados en esta tesis fueron que a través de la implementación de métodos geomáticos, sensores remotos, técnicas estadísticas de machine learning (RF y SVR) y biomasa estimada con variables dasométricas, se lograra establecer un modelo geoespacial que permitiera predecir la distribución espacial de la biomasa en el estado de Durango, específicamente en el área de bosques templados. Se desarrollaron múltiples campos de investigación geomática mediante la implementación de programación y modelación estadística satelital, y métodos geoestadísticos. El procesamiento de la información mediante estas metodologías, permitió confeccionar la base de datos geoespacial que conformarían las cuarenta y cuatro variables predictivas. El rendimiento estadístico de los modelos de machine learning evaluados denota que SVR es un modelo robusto y estable en la evaluación de grandes bases de datos espaciales, ya que, dentro de su entrenamiento y optimización, ninguna variable necesita ser excluida. El costo computacional de SVR es mejor respecto a RF. Se precisa que con SVR se obtiene una confiabilidad estadística del 80 % en la estimación de la biomasa forestal en el estado de Durango, por lo cual se puede considerar un modelo de fácil aplicación, bajo costo computacional y muy optimo en la estimación de atributos forestales.

The expansion of built-up areas in the city is one of the major research subjects in urban planning and development. It indicates how much the built-up area is increasing and the rate of increase over time. Also, the specific regions which are potential for future urban development can be enumerated. This paper uses two methods for built-up area extraction. The first method incorporates the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Built-up Index (NDBI) to extract built-up area from LANDSAT-7-LANDSAT-8 imagery. The second method added Normalized Difference Water Index (NDWI), Short Wave Infrared (SWIR), and Thermal Infrared (TIRS) for built-up area extraction. This study’s primary goal is to identify the difference of built-up areas over time. Three years of LANDSAT-7 and LANDSAT-8 imagery (1999, 2013, and 2018) of Khulna city, Bangladesh, has been used in this study. The difference between the two conventional methods has also been reviewed. The satellite image analysis results reveal that the built-up area expansion from 1999 to 2013 is significantly higher than from 2013 to 2018. Results from the two different methods indicate that the use of NDWI, SWIR, and TIRS can increase the accuracy of extracting built-up areas.

The variation between surface and air temperature within a city and its surrounding area is a result of variations in surface cover, thermal capacity and 3-dimensional geometry. This study examines the spatiotemporal formation of the daytime Surface Urban Cool Island (SUCI) and night-time Surface Urban Heat Island (SUHI) effect in Erbil, Iraq, as a case study for cities in semi-arid climates more generally. It furthermore quantifies the influence of rapid urban expansion on the urban heat/cool island effect over a 20 year period.
    Satellite images acquired by Landsat 4, 5, 7 and 8 between 1992 and 2013 are used to retrieve Land Surface Temperature (LST). Normalised Ratio Scale (NRS) is applied to the multi-mission Landsat data, which is used to adjust the temperature range for different acquisition times of images within the same temporal range. In addition, LST data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on board Aqua and Terra from January 2003 to December 2014 are analysed. In order to establish the drivers of the observed patterns of LST and SUCI/SUHI, the relationships of LST with wetness, greenness, NDVI, soil moisture and other variables are assessed.
    The results indicate that during the daytime in summer, autumn and winter, densely built-up areas had lower LST acting as cool islands (SUCI) compared to the non-urbanised area around the city. In contrast, at night-time, Erbil experienced higher LST and demonstrated a significant SUHI effect. The mean LST of the newly urbanised and vegetated areas between 1992 and 2013 decreased by 2.28°C and 7.29°C respectively. Soil moisture (wetness) is the main marker of the SUCI/SUHI effect, whilst urban expansion may cause a decrease of daytime LST in dry climate zones. The NRS method is appropriate for detecting temperature trends greater than 2°C in Landsat data.

Lajunya perubahan tutupan hutan menjadi non hutan dalam pengelolaan hutan sangat perlu di monitoring untuk mengetahui seberapa besar perubahan dan garaimana trend konversi tutupan lahan. Monitoring ini dipermudah dengan adanya Sistem Informasi Geografis, teknologi penginderaan jauh dan sumber informasi dari WebGIS Kementerian Lingkungan Hidup dan Kehutanan. Tujuan penelitian ini untuk menganalisis perubahan tutupan lahan dan melihat kecenderungan (trend) pola perubahan tutupan lahan di Kota Balikpapan dengan menggunakan 8 seri data mulai dari tahun 1990-2016. Hasil yang diharapkan dari penelitian ini adalah dapat memberikan informasi mengenai kondisi tutupan lahan terbaru tahun 2016 dan dinamika perubahan tutupan lahan yang terjadi di Kota Balikpapan selama 26 tahun terakhir. interpretasi secara visual atau digitizing on screen dengan memperhatikan 9 unsur interpretasi seperti rona/warna, bentuk, ukuran, tekstur, situs, pola, bayangan, asosiasi dan kovergensi bukti dan dikelaskan dalam 23 jenis tutupan lahan sesuai dengan SNI No. 7645 Tahun 2010. Hasil interpretasi dianalisis dengan menggunakan teknik overlay dan dilakukan perhitungan luas perubahan tutupan lahan untuk melihat jenis dan trend perubahan lahannya. Tingkat akurasi hasil interpretasi di uji dengan confusion matrix yang membandingkan antara hasil interpretasi dengan hasil ground check lapangan. Hasil interpretasi citra didapatkan 13 jenis tutupan lahan yang terdapat di Kota Balikapapan. Berdasarkan hasil interpretasi tutupan yang paling luas adalah pertanian lahan kering campur semak dengan luasan rata-rata sebesar 17.678,01 ha dengan jenis perubahan yang paling sering terjadi dalam periode 26 tahun adalah dari pertanian lahan kering campur semak ke permukiman dengan luas perubahan sebesar 7.195,54 ha. Hasil analisis tutupan lahan selama 26 tahun, trend positif terjadi pada hutan lahan kering primer dan semak belukar rawa, sedangkan trend negatif terjadi pada tutupan hutan lahan kering sekunder, hutan mangrove primer dan sekunder, pertanian lahan kering campur semak, semak belukar, rawa, permukiman, lahan terbuka dan bandara/pelabuhan. Tingkat akurasi interpretasi dalam penelitian ini sebesar 89,52 % dengan akurasi kappa sebesar 0,87.

Kata kunci : Tutupan lahan, interpretasi visual, Kota Balikpapan, akurasi interpretasi.

The Ganga/Ganges 1 is an important river system in South Asia which supports the life and livelihoods of millions of people both in India and Bangladesh. The system has a number of names throughout its length. Below its con-fluence with the Brahmaputra at Aricha it is known as the Padma, which in turn merges with the Upper Meghna at Chandpur below which the channel is known as the Lower Meghna. There is a growing concern about this large river system because its channels are subject to frequent migration, threatening engineering structures and resulting in various environmental and social consequences which may be compounded by climatic variability, land use change, and agricultural intensification as the basin experiences rapid population growth. Concerns have been expressed that the construction of a barrage just upstream of the Indo–Bangladesh border has adversely affected the Ganges reach in Bangladesh. Partly in order to investigate this, the planform changes of the Ganges and the Padma within Bangladesh was analysed over the period 1973 to 2011 using multitemporal Landsat images and long–term flow data in eight epochs with an average duration of 4.5 years. The Padma reach is less affected by the barrage and provides a useful control study. Areas of erosion and deposition were determined from sequential changes in the bankline positions. Mean channel width, sinuosity and braiding index were analysed using a Geographic Information System (GIS). Flood frequency, duration and magnitudes were studied using long-term discharge records. Generally, channel planform evaluation indicated that both the Gan-ges and the Padma experienced contraction, expansion and readjustment in configuration over the last 38 years. Erosion and deposition statistics of the Ganges indicate that 57 km 2 of land was lost along the right bank whereas around 59 km 2 has been gained along the left bank during the assessment period, suggesting that the erosion and accretion of both banks is roughly balanced with a general movement towards the right bank. The width of the Ganges varied from a maximum of 5.36 to a minimum of 3.23 km during the observation period. Changes to sandbar area are, in general, much more radical than changes to the overall width and area of the channel. Measurement of areas of erosion and accretion showed that both banks of the Padma experienced considerable loss of land. The total net loss for left bank and right bank was 155 and 28 km 2 , respectively. The Padma is approximately twice the width of the Ganges and the changes to its channel area are not as temporally dynamic as the Ganges. The relationship between bank curvature and erosion/accretion of the river banks for both rivers was analysed and the results contradict established meander theory. Regression analysis between bank erosion rates, annual average discharge and mean flood flow data showed that bank erosion was significantly correlated with annual average discharge for the Padma (r 2 = 0.6283) and that the Ganges bank erosion rate is influenced by mean flood flow (r 2 = 0.6738). The flood frequency shows generally good stability across the first eight of the nine epochs for the Ganges but for the Padma the frequency showed even greater stability. We were unable to support the widely held belief that the upstream barrage has a deleterious effect on the Ganges but note that there is a slight effect due to the periodic release of sediment through scour sluices.

The study examines long-term land use/land cover change (LUCC) at a finer scale in a semi-arid region of India. The objectives were to study and quantify the spatiotemporal LUCC and uncover the major drivers causing the change in the Mula Pravara river basin, which is located in a semi-arid region of Maha-rashtra state, India. Advanced very high-resolution radi-ometer (AVHRR)-Normalized Difference Vegetation Index (NDVI) 3g data for the years 1982-2015 were used to identify the 'hotspot' with significant positive and negative LUCC. Multi-temporal Landsat imagery was used to produce finer scale land use maps. From 1991 to 2016, the agricultural land area increased by approximately 98% due to the conversion of uncultiva-ble and fallow lands to agriculture. The built-up area increased by 195%, and in recent years, an urban expansion has occurred in agricultural lands close to the urban fringe areas. There has been a shift from food crops to commercial crops, as observed from the steep increase in the amount of land under horticultural plantations , by 1601% from 2001 to 2016. In addition, the area under forest canopy was reduced in the protected regions. Institutional factors that improved access to water resources were the major drivers of change in hotspots, especially in the context of agriculture. Technological and economic factors were the other supporting factors that contributed to the change. This study demonstrates the advantages of using satellite remote sensing techniques to monitor the LUCC, which is useful for predicting future land changes and aids in planning adaptation strategies.

O presente estudo se propõe a uma análise comparativa das microbacias dos ribeirões Santo Antonio /Pontal do Paranapanema/Oeste de São Paulo, São Francisco/Noroeste do Paraná e Três Barras/Sudeste do Mato Grosso do Sul, que, embora relativamente próximas, estão inseridas em unidades geo-ecológicas diversas e que foram submetidas a processos socioeconômicos, cultural, gestão e apropriação também diversos. O elo de ligação entre estas três microbacias é o rio Paraná, pois a gestão do mesmo interferirá em toda evolução de forma integrada, além de que, atualmente, o referido rio vem sofrendo mudanças sócio-ambientais em decorrência do enchimento do reservatório da Usina Hidrelétrica Engenheiro Sérgio Motta-Porto Primavera (alto curso), desencadeando significativos impactos de um lado e obras compensatórias e mitigatórias de outro. Desta maneira, convém conhecer um pouco mais do processo de consolidação destas microbacias:
- Ribeirão Santo Antonio: o uso da terra se deu por contratos de arrendamento. Para o arrendatário não apareceu outra preocupação senão o lucro; o quadro de exploração se agrava com o incentivo de agroindústrias “móveis”, principalmente na década de 70, como a Sanbra e Mac Fadem;
- Ribeirão São Francisco: houve um parcelamento em pequenas propriedades, exploradas, regra geral, pelo proprietário e sua família e orientado por um plano de desenvolvimento regional pilotado pela Companhia de Terras Norte do Paraná (CTNP);
- Ribeirão Três Barras: o início da ocupação se deu num contexto em que a agricultura já não tinha os mesmos atrativos das décadas de 40 ou 60 (como nos outros dois ribeirões) e, também é caracterizada por expansão de fazendas pecuaristas (que também são bastante impactantes). O grande impacto de assoreamento e gestão dos recursos hídricos foi dado pelo uso e não pela potencialidade física, o que faz com que cada uma das microbacias reaja diferenciadamente.
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RESUMÉ: Ce travail propose de faire une analyse comparative des bassins-versants des "ribeirões" Santo Antônio (situé dans le Pontal du Paranapanema, à l'Ouest de l'État de São Paulo), São Francisco (dans le Nord-Ouest de l'État du Paraná) et Três Barras (dans le SudEst de l'État de Mato Grosso do Sul). Malgré la relative proximité entre les trois bassinsversants, ceux-ci font partie d'unités géo-écologiques différentes et ont été soumises à des processus socio-économiques, culturels et d'aménagements dissemblables. Le point d'intégration entre les trois bassins-versants est le Rio Paraná, puisque son aménagement interfère dans l'évolution socio-économique de toute la région. En outre, depuis quelques années, le Rio Paraná a connu d'importants changements socio-environnementaux avec la construction de l'Usine Hydroéléctrique Sérgio Motta, qui a entraîné des impacts négatifs ou positifs. Ainsi, il s'agit de connaître un peu plus le processus de consolidation de ces bassins-versants.
• Ribeirão Santo Antônio: la mise en valeur a été faite par "arrendamento", une modalité d'exploration très lucrative pour les propriétaires des terres;
• Ribeirão São Francisco: la mise en valeur a été faite par l'implantation de petites propriétés d'exploration familiale orientées surtout par le plan de développement régional de la Compagnie des Terres du Nord du Paraná (CNTP);
• Ribeirão Três Barras: le commencement de l'ocupation a eu lieu après l'euphorie de l'activité agricole des années 1940 à 1960 (que les deux autres bassins-versants ont connu) et se caractérise par l'implantation des grandes propriétés d'élévage bovin (Aussi avec beaucoup d´impacts). Dans les trois bassins-versants, l'ensemble des impacts sur les ressources hydriques ont été causé par l'occupation démesurée des terres, sans tenir compte des potentialités physiques. Le résultat est la production d'effets différents dans chaque bassin-versant.

Urbanisation leads to rapid constructions, which use low albedo materials leading to high heat absorption in urban centres. In addition, removal of vegetation cover and emissions of waste heat from various sources contribute to the accumulation of heat energy, leading to formation of urban heat islands (UHIs). UHIs have many adverse socio-environmental impacts. Therefore, spatial identification of UHIs is a necessity to take appropriate remedial measures to minimise their adverse impacts. Satellite remote sensing provides a cost-effective and time-saving methodology for spatio-temporal analyses of land surface temperature (LST) distribution.

In this study, thermal bands (10.40–12.50 μm) of Landsat-7 ETM+ imagery acquired in 3 distinct dates covering Colombo city of Sri Lanka were analysed for the spatio-temporal identification of UHIs. Vegetation cover of Colombo city was extracted by using NDVI method and subsequently examined with the distribution of LST.

A deductive index was defined to identify the environmentally critical areas in Colombo city based on the distribution of LST and availability of vegetation cover. Accordingly, Colombo harbour and surrounding areas were identified as the most critical areas. Remedial measures can be taken in future urban planning endeavours based on the results of this study.

Surat city has emerged as an earmarked urban space drifting with the development of built-up areas. The momentum was observed in the
decadal census of the year 2001 while the city registered a decadal growth rate of higher than 88%. Globally, the city is ranking among the top hundred considering various lists, and yet the pace is not slowed down. The emerging buildings are occupied in d ifferent purposes viz. residential, commercial, institutional and industrial as well. Along with buildings, connectivity through more extensive and planned roads and other i nfrastructure are also made available to citizens migrating in and settling in the city. The current research work is aiming to understand and analyse the developmental trend spatially (NDVI based) on an annual temporal scale for the duration since the year 1995 till 2019. Satellite images of Land SAT mission s of 4 5, 7 and 8 are used
for processing and extracting information of the past situations. Area delineation for the analysis was made considering the administrative boundary of the Surat Urban Development Authority (1357 km2). Not only the direction of development is identified, but also, the area being converted in the built-up spaces is worked out. The findings are suggesting the growth (planned though) in the North-east and South West directions. These are towards the inland and away from the Arabian Sea in the West. The developed spaces are consuming agricultural pastures in the fringe. The annual rainfall has significantly allowed for agrarian activities around the year, adding prosperity among citizens. Authors attempted to discuss the results of an analysis for
minimum and maximum temperatures and rainfall pattern for a duration of two decades. Also, the developing areas are identified to be vulnerable to inland flooding and sea surge as projected through global IPCC Models. The paper discusses the details with possible remedial measures through the mechanism of modifications in the existing planned land use (development plan).