Persistent scatterer interferometric analyses were conducted on a stack of 84 Environmental Satellite's Advanced Synthetic Aperture Radar scenes spanning 7 years (2004 to 2010) over the entire Nile Delta of Egypt and surroundings (area: 40,416 km2) to monitor the ongoing spatial and temporal land deformation, identify the factors controlling the deformation, and model the interplay between sea level rise and land subsidence to identify areas and populations threatened by sea encroachment by the end of the 21st century. Findings include the following: (1) general patterns of subsidence (average rate: −2.4 mm/year) in the northern delta, near‐steady to slight subsidence in the southern delta (average rate: 0.4 mm/year), separated by a previously mapped flexure zone (minimum width: 20–40 km) undergoing uplift (average rate: 2.5 mm/year); (2) high subsidence rates (up to −8.9 mm/year) over the north central and northeastern delta (area: ~4,815 km2), possibly due to compaction of recent (5 m) silt and clay‐rich Holocene sediments; (3) high subsidence rates (up to −9.7 mm/year) in areas where the highest groundwater extraction rates were reported in southern delta (Menoufia governorate) and in reclaimed desert land in the western delta (Beheira governorate); (4) high subsidence rates (up to −9.7 mm/year) over onshore gas fields, notably the Abu Madi gas field, where high gas extraction rates have been recorded; and (5) using extracted deformation rates, high‐resolution TanDEM‐X digital elevation model, a eustatic sea level rise of 0.44 m, and applying a bathtub inundation model, an estimated 2,660 km2 in northern delta will be inundated by year 2100.
1 April 2011 in International Journal of Coal Geology
The rapid increase in the population of many of the older major cities within the countries of the Saharan-Arabian Desert is steering vast and disorganized urban expansion and in many cases introducing adverse environmental impacts such as soil erosion, rise in groundwater levels, and contamination of shallow aquifers, as well as development of deformational features including land subsidence. Using the rapidly growing city of Riyadh (1992: 467 km2; 2018: 980 km2), the capital of the Kingdom of Saudi Arabia as a test site, we utilized Small Baseline Subset (SBAS) interferometric analyses of 2016 to 2018 Sentinel-1 images together with multi-temporal high-resolution images viewable on Google Earth, GPS, field, land use land cover (LULC), and geological data to assess the distribution and rates of land subsidence and their causal effects. Three main causes of subsidence were identified and assessed: (1) discharge of wastewater effluents from septic systems in newly urbanized areas that lead to an increase in soil moisture, rise in groundwater levels, waterlogging, and wetting and hydrocompaction of dry alluvium loose sediments causing land subsidence (up to −20 mm/y) in wadis and lowlands; (2) the subsurface dissolution of karst formation by wastewater effluents and the collapse of voids and cavities at depth under stresses introduced by heavy construction machinery, causing sagging and land subsidence (up to −5 mm/y); and (3) leveling, compaction, and degradation of municipal and building waste materials in organized landfills and disorganized dump sites that resulted in significant land subsidence (up to −21 mm/y) and differential settling that could jeopardize the stability of structures erected over these sites. Our findings highlight the potential use of the advocated integrated approach to assess the nature and extent of land deformation associated with rapid urban growth in arid lands, and to identify areas most impacted for the purpose of directing and prioritizing remediation efforts.
8 December 2011 in International Journal of Mining, Reclamation and Environment
Surface mining activities, exploitation of ore, and stripping and dumping of the overburden cause changes in the land cover and land use of a mine area. The area of land disturbance can be very large in the case of surface coal mining, due to the nature of the coal extraction process. Sustainable mining requires continuous monitoring of changes in land cover and land use induced by the mining activities. This is essentially important for identifying the long-term impacts of mining on theenvironment and on land cover in order to provide necessary mine closure andreclamation measures. In this sense, digital image classification provides apowerful tool for obtaining rigorous data, and reduces the cost of field measurements in time and money, particularly when dealing with large areas. Various remote sense data records and image classification techniques serve different features for numerous purposes. The selection of a suitable data and image classification method is significant for ensuring the effective use of information extracted from the satellite images, e.g. land-use classes. This paper proposes a methodology for identifying land-use change in surface coal mines using multi-temporal high-resolution satellite images. The methodology has been implemented for identifying, quantifying and analysing the spatial response of landscape to surface mining activities in the Goynuk, Bolu surface mine in Turkey, from 2004 to 2008. The methodology essentially entails (i) acquiring data, (ii) preprocessing the data, (iii)image classification using the maximum likelihood classification algorithm (iv) accuracy assessment and (v) change detection analysis depending on class-based approaches. The results show that the methodology can be utilised effectively in monitoring land-use change in surface coal mining areas. It also provides essential input for planning mine reclamation and closure activities.