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This study evaluated historical land-cover states in order to identify potential land-use transition regimes leading to land degradation. Landsat satellite datasets were used to characterize land-cover states for 1986–2017 period. The multinomial probability distribution was used to establish sample size for training and accuracy assessment. Using a hybrid image classification approach, individual satellite images were initially clustered using the ISODATA technique, and spectral classes later transformed posteriori into respective thematic classes. Maximum Likelihood Function was subsequently used to assign pixels into classes with highest probability. Approximately 12% of mixed forest declined, while cropland increased by 30% between 1995–2008. [ABSTRACT FROM AUTHOR]

Wetlands are some of the most diverse ecosystems in the world. The accurate mapping of wetland types and monitoring their dynamic changes provide the scientific foundation for wetland conservation and restoration. Aligarh district, located in Uttar Pradesh, had many wetlands but due to encroachment, they are shrinking. No wetland mapping has been done before to compare the past and present situation of wetlands. Therefore under this study, an attempt has been made to understand the status of wetlands in the Aligarh district in terms of their number and extent and also assess the temporal changes during 2002-2017 using the multi-temporal Landsat imageries. Supervised Classification with the Maximum Likelihood algorithm was used to classify the wetlands. We found that about 3988 ha area was covered by wetlands, which is one per cent of the total geographic area of the district. The maximum number of wetlands were point wetlands currently (having less than 1 ha area). In the last 15 years, the area of wetlands decreased by 49%. The overall accuracy of the supervised image produced was 87.50% with a kappa value of 0.75. [ABSTRACT FROM AUTHOR]

One out of three people in India is urban. In 2011, there were about 53 urban agglomerations larger than 1 million population as against only 35 in 2001. Much of this urban expansion has been occurring in the country's largest metropolises including the National Capital Territory of Delhi which has expanded horizontally and vertically both. This has also added to overall decline in its already dilapidated housing stock and quality of life. Delhi, a historical hub for regional, national, and international commerce, and a place for the socio-political elites, has failed to provide basic life amenities to its average citizens. This research critiques the (un)sustainable elements of Delhi's urbanization and concomitant decline in basic amenities pertaining to quality-of-life by examining the growth and expansion of its urban-built-up areas during 2001–2011–2020 and provides nuanced insights into its 'livability' by examining select quality-of-life attributes. The LANDSAT imageries for 2010 and 2020 are used to measure NDB-Index that assesses its built-up area and change, which are later corroborated with Census household data to examine change in its 'livable' and 'dilapidated' housing structures. Significant sub-regional disparity exists in the availability of good and livable homes, with almost 20–30% of several districts still without drinking water source inside premises. However, significant progress is also noted for basic amenities like lighting, latrine and bathing facilities, and majority of Delhi's built-up area has expanded along newer developments and transportation corridors. This calls for goal-oriented strategic interventions by policymakers to help achieve the SDG-11 on Sustainable Cities. [ABSTRACT FROM AUTHOR]

The continuous monitoring of the relationship between land surface temperature (LST) and land cover change is imperative for an inquiry into the potential impact of LST on human well-being, including urban outdoor thermal comfort in Lagos State, Nigeria. Using Landsat imagery, this study assessed land cover and LST changes from 1984 to 2019. Land cover was extracted, LST was determined from Landsat imageries and the land cover changes were linked to LST using the contribution index (CI). Afterwards, the universal thermal climate index (UTCI) was calculated to determine the heat stress levels. Findings confirm the presence of urban sprawl and new growth areas in previously rural Local Government Areas (LGAs) eastward, northward and westward of Lagos metropolis and in regions which lie on the fringe of the state's border with Ogun State. Also, a very strong link between high LST intensities and increasing concentration of urban areas in rapidly growing LGAs has been observed. This link further confirms the increased warming of the state, with an increase in mean LST of 2.16°C during 1984–2019. The UTCI which was used to gauge the influence of LST on outdoor thermal comfort ranged from moderate to strong heat stress levels. This study helps to strengthen the case for definite policies and actions which should be aimed at achieving moderate urban development through increased urban tree canopy/green infrastructure provision and carbon sequestration activities in urban design/landscape design, in Lagos State.

The northern half of the Maputaland Coastal Plain (MCP) of South Africa has undergone significant change in land-use over the last five decades, including afforestation, agriculture and rural settlements. To understand the extent of land-use changes that took place in the northern half of the MCP from 1986 to 2019 and its efficacy, various Landsat satellite images that are freely available were processed, analysed and interpreted. The cloud-based Google Earth Engine (GEE) platform was used to determine the land-use changes. The random forest classification algorithm available within GEE was used to classify the Landsat 5 Thematic Mapper, Landsat 7 Enhanced Thematic Mapper Plus and Landsat 8 Operational Land Imager images for 1986, 1991, 1996, 2001, 2006, 2011, 2016 and 2019. The development of plantations was tracked, which indicated that forestry increased by more than 100% between 1986 and 2019. Over the same period, surface water bodies and wetlands decreased by 36.1% and 49.1%, respectively. In addition to forestry, climate had a major impact on water resources in the MCP. Given that the MCP is a predominately groundwater-driven system, the impact of increased plantations on groundwater is an area that requires more investigation. This will improve the understanding of water resources in the area. Conservation implications: The management, protection and conservation of water resources within protected areas are entwined with land-use decisions and planning outside of its boundaries. The rapid change in land-use experienced outside of protected areas and its impact on water resources disregard boundaries and may transgress on protected areas.

The fragile Sudano-Sahelian ecological zone of Nigeria has been classified as a hotspot of land cover change (LCC) that has been suffering from serious anthropogenic and biophysical stresses. Damaturu, being the fastest growing town situated in the region happened to be a victim of this negative development. The purpose of this study is to remotely observe and assess the prevailing land-use/land-cover (LULC) dynamics of Damaturu town and its delicate surrounding lands from the year 1987-2017 study periods. To achieve this, a supervised image classification technique with Maximum Likelihood Classifier (MLC) algorithm was used in ERDAS Imagine version 15 software to classify the three epochs multi-temporal and multi-spectral Landsat imageries (TM 1987, ETM+7 2000 and OLI 2017). The classified LULC maps and their resulting statistics were then used to assess the spatio-temporal aspects of the observed changes by placing the results within the wider context of previous related literature and evidences. Findings revealed that the built-up area has been expanding since 1987 with an annual change rate of 4.5% between 1987-2000, and 5.3% during 2000-2017 respectively. The growth of the town is being accompanied by massive farmlands expansion and vegetal cover (trees and shrubs) lost making the surrounding arable lands seriously disturbed. Thus, if the observed trends continue, the entire studied region will be subjected to severe environmental hazard such as desertification. Overall, the study provides valuable information required for sustainable environmental management.

The study examined the spatial and temporal variation of land surface temperatures over a typical medium-size traditional settlement in southwestern Nigeria. Data were the multi-date satellite Landsat imageries (1991, 2002 and 2015) covering the area, as well as values of ambient air temperatures that were measured at different landuse areas (industrial, commercial, residential and outskirts) and along the major road that traverse the study area using a portable handheld air weather station thermometer. Ambient temperature values were obtained between 0600 and 1900 hours of the Nigerian local standard time. Analysis of the Landsat imageries indicate that thermal reflectance (in terms of normalized difference build-up index, NDBI) has generally increased between 1991 and 2015 by about 92 %. The NDBI shows that temperature has increased over the built up regions by 49 - 52 % between 1991 and 2015. Average land surface temperature (LST) in the area also increased by about 2.2 oC (22.8 oC - 25 oC) in the study period, but with higher than average increase around road junctions, industrial and commercial centres. Analysis of diurnal variation showed that daytime temperature was about 0.5 - 1.4 oC higher in the afternoon than either the morning or evening. The study concluded that increased in anthropogenic activities, including urbanization and commercialization are main causes of temperature increase in the traditional area, and that remote sensing imageries and in situ measurements of temperature are complementary for monitoring of changes in urban climate.

The northern half of the Maputaland Coastal Plain (MCP) of South Africa has undergone significant change in land-use over the last five decades, including afforestation, agriculture and rural settlements. To understand the extent of land-use changes that took place in the northern half of the MCP from 1986 to 2019 and its efficacy, various Landsat satellite images that are freely available were processed, analysed and interpreted. The cloud-based Google Earth Engine (GEE) platform was used to determine the land-use changes. The random forest classification algorithm available within GEE was used to classify the Landsat 5 Thematic Mapper, Landsat 7 Enhanced Thematic Mapper Plus and Landsat 8 Operational Land Imager images for 1986, 1991, 1996, 2001, 2006, 2011, 2016 and 2019. The development of plantations was tracked, which indicated that forestry increased by more than 100% between 1986 and 2019. Over the same period, surface water bodies and wetlands decreased by 36.1% and 49.1%, respectively. In addition to forestry, climate had a major impact on water resources in the MCP. Given that the MCP is a predominately groundwater-driven system, the impact of increased plantations on groundwater is an area that requires more investigation. This will improve the understanding of water resources in the area. Conservation implications: The management, protection and conservation of water resources within protected areas are entwined with land-use decisions and planning outside of its boundaries. The rapid change in land-use experienced outside of protected areas and its impact on water resources disregard boundaries and may transgress on protected areas. [ABSTRACT FROM AUTHOR]

The coastal wetlands of Chennai are increasingly being affected by anthropogenic factors, such as urbanization, residential, and industrial development. This study helps to monitor and map the dynamics of the coastal wetlands of Chennai using Landsat satellite images of 1988, 1996, 2006, and 2016 by following a supervised classification method. Post-classification wetland change detection was done in three temporal phases, that is, 1988-1996, 1996-2006, and 2006-2016. Change detection matrix analysis was performed to identify the from-to changes. Ground truthing was carried out to validate the wetland classes. The overall accuracy of the classified image was 79.29% and the kappa coefficient was 0.7600. These results were imported into a GIS environment for further analysis. It was found that the wetlands have decreased to an alarming extent in the past 28 years from 23.14% in 1988 to 15.79% in 2016 of the total study area, owing to conversion of wetlands into industrial development, urban expansion, and other developmental activities. [ABSTRACT FROM AUTHOR]

The study examined the spatial and temporal variation of land surface temperatures over a typical medium-size traditional settlement in southwestern Nigeria. Data were the multi-date satellite Landsat imageries (1991, 2002 and 2015) covering the area, as well as values of ambient air temperatures that were measured at different landuse areas (industrial, commercial, residential and outskirts) and along the major road that traverse the study area using a portable handheld air weather station thermometer. Ambient temperature values were obtained between 0600 and 1900 hours of the Nigerian local standard time. Analysis of the Landsat imageries indicate that thermal reflectance (in terms of normalized difference buildup index, NDBI) has generally increased between 1991 and 2015 by about 92%. The NDBI shows that temperature has increased over the built up regions by 49 - 52% between 1991 and 2015. Average land surface temperature (LST) in the area also increased by about 2.2 °C (22.8 °C - 25 °C) in the study period, but with higher than average increase around road junctions, industrial and commercial centres. Analysis of diurnal variation showed that daytime temperature was about 0.5 - 1.4 °C higher in the afternoon than either the morning or evening. The study concluded that increased in anthropogenic activities, including urbanization and commercialization are main causes of temperature increase in the traditional area, and that remote sensing imageries and in situ measurements of temperature are complementary for monitoring of changes in urban climate. [ABSTRACT FROM AUTHOR]

River bank accretion/erosion is the most important geomorphological processes in natural process attracting a great deal of attention from river engineering scientist. In this study, river bank accretion/erosion assessment in the confluence of Thao-Da-Lo rivers in the period of 1986-2017 is presented based on the combination of histogram thresholding and band ratio techniques. Landsat 5 TM and 8 OLI imageries were first used of river bank extraction, GIS was then employed to assess river bank changes and accretion/erosion. It was found that, Thao-Da-Lo river banks have changed complexly, especially on the left bank. Accretion and erosion occurred frequently on both sides of the river, mainly occurred in the left bank of the confluence area such as Tan Duc (Ba Vi district), Minh Nong and Ben Got (Viet Tri city). Almost no erosions were found in the right bank (Phong Van, Co Do, Phu Cuong, Tan Hong, Chau Son and Phu Phuong) in this period. The study showed the effective use of remote sensing and GIS in river bank accretion/erosion assessment. [ABSTRACT FROM AUTHOR]

This paper aimed at assessing drought occurrences and its effects on vegetation cover in Sokoto State, Nigeria using geospatial and statistical techniques. Monthly precipitation data which span through a period of 40 years (1980-2010) and 30 years (1982-2011) respectively were used for generating Standardized Precipitation Index (SPI) graphs and maps. LandSat imageries of bands 3 and 4 acquired by Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) Sensor were used for generating Normalized Difference Vegetation Index (NDVI). SPI and NDVI were generated for the study area based on inter-annual and decadal timescale. Findings showed that SPI values varied from extremely dry condition to extreme wet condition although near normal condition ranked highest while extremely wet condition ranked least. It also revealed that most of the Local Government Areas experienced near normal conditions but Isa, Sabon Birni and little part of the boundary between Goronyo and Wurno experienced moderately wet conditions between 1982 and 1991. It was further observed that the whole region was dominated with near normal condition except Sabon Birni and Isa LGAs that experienced extremely, severely and moderately wet condition between 1992 and 2001. In contrast, the SPI values for over 90% of the state between 2002 and 2011 fall within the severely dry conditions. Findings further showed that change scenarios observed from the derived NDVI and SPI maps indicated that the climatic variability currently being experienced is likely to increase and intensify in future. It is obvious that urgent attention on drought management over this region is needed. [ABSTRACT FROM AUTHOR]