Ground subsidence in Semarang-Indonesia investigated by ALOS–PALSAR satellite SAR interferometry

The focus of this study is investigation of land subsidence in Semarang city Indonesia with the use of Interferometry Synthetic Aperture Radar (InSAR) of ALOS–PALSAR satellite. We processed 22 ascending SAR images during January 2007 to January 2009 plus two descending SAR images acquired on 6 June 2006 and 17 June 2007. The time series analysis of interferometry was performed by using 12 pairs of interferogram relative to 21 January 2007 and 8 pairs of interferogram relative 24 January 2008. The topographic phase contribution was removed using the 3-arcsec (90 m) Shuttle Radar Topography Mission (SRTM), Digital Elevation Model (DEM). We performed precision baseline estimation to vanish the fringes from baseline effect between master and slave data. In order to investigate the contribution of horizontal movement in our analysis, we constructed two interferograms of ascending orbit and descending orbit. The time series results exhibited that the area is subsiding continuously without a significant seasonal effect during January 2007 to January 2009. The land subsidence observed from InSAR data is approximately up to 8 cm/year. Three cross sections on image displacement show the extreme land subsidence occurred especially along the coastal area and lowland area where this area is considered as industrial with high-density settlements, consuming a lot of groundwater, and land is changed from agriculture and cultivation purposes to industrial estates and house. Our result also shows a consistency with historical pattern of subsidence measured by leveling data. The results highlight the potential use of InSAR measurements to provide better constraints for land subsidence in Semarang city Indonesia.     

Review: Water–rock interactions and related eco-environmental effects in typical land subsidence zones of China

Land subsidence is common in some regions of China. Various eco-environmental problems have arisen due to changes in water–rock interactions in these subsided areas, for which a comprehensive understanding of the hydrogeological setting is needed. This paper presents the general status of land subsidence in three typical subsided areas of China through the compilation of relevant data, and reviews some typical changes in the water–rock interactions in subsided areas along with related eco-environmental issues. It is found that the subsidence development and distribution are controlled by the groundwater-withdrawal intensity externally, and by the thickness and compressibility of unconsolidated sediments internally. The physical changes and related effects of water–rock interactions in subsided areas include: (1) the decreased ground elevation that caused floods, waterlogged farmland, etc.; (2) the differential subsidence that caused ground fissures; and (3) the change of seepage field that caused substantial reduction of the water resource. Chemically, the changes and related effects of water–rock interactions include: (1) the change to the chemical environment or processes due to the hydrogeologic structure alteration, which caused groundwater pollution; and (2) hydrologic mixing (seawater intrusion, artificial recharge; exchange with adjacent aquifers or aquitards), which degraded the groundwater quality. Further research on the subsided areas in China is suggested to reveal the mechanisms regarding biological and gaseous (meteorological) changes from the perspective of interacting systems among water, rocks, biological agents and gases.     

Long-term groundwater storage changes and land subsidence development in the North China Plain (1971–2015)

The North China Plain (NCP) has been suffering from groundwater storage (GWS) depletion and land subsidence for a long period. This paper collects data on GWS changes and land subsidence from in situ groundwater-level measurements, literature, and satellite observations to provide an overview of the evolution of the aquifer system during 1971–2015 with a focus on the sub-regional variations. It is found that the GWS showed a prolonged declining rate of ?17.8?±?0.1 mm/yr during 1971–2015, with a negative correlation to groundwater abstraction before year ~2000 and a positive correlation after ~2000. Statistical correlations between subsidence rate and the GWS anomaly (GWSA), groundwater abstraction, and annual precipitation show that the land subsidence in three sub-regions (Beijing, Tianjin, and Hebei) represents different temporal variations due to varying driver factors. Continuous drought caused intensive GWS depletion (?76.1?±?6.5 mm/yr) and land subsidence in Beijing during 1999–2012. Negative correlations between total groundwater abstraction and land subsidence exhibited after the 1980s indicate that it may be questionable to infer subsidence from regional abstraction data. Instead, the GWSA generally provides a reliable correlation with subsidence. This study highlights the spatio-temporal variabilities of GWS depletion and land subsidence in the NCP under natural and anthropogenic impacts, and the importance of GWS changes for understanding land subsidence development.     

Survey of land subsidence – case study: The land subsidence formation in artificial recharge ponds at South Hamadan Power Plant,northwest of Iran

Journal of Earth System Science - The artificial recharge is a technique of aquifer conservation for land subsidence. But in this article, the phenomenon of land subsidence and the resulting cracks...     

The Lagoon of Venice： geological setting,evolution and land subsidence

The paper deals with the geological setting, history and subsidence of the Venetian Plain. Major attention is paid to the Pleistocene-Holocene stratigraphic sequence in the Lagoon of Venice, in relation to its origin that datesback to 6-7 kyr BP. Geological land subsidence, which played an important role in the origin and the evolution of the lagoon, and anthropogenic subsidence, that has recently assumed a major importance for the Venetian environment, are discussed. Considering also the sealevel rise, 23 cm loss in land elevation has occurred in the last century, leading to increased flooding events and environmental problems that require protective works.     

Detection of ground deformation over Sharm El-Sheikh–Ras Nasrani coastal zone,South Sinai (Egypt), by using time series SAR interferometry

The investigation area is located in the most southern part of Sinai Peninsula boarded from the west by the Gulf of Suez and from the east by the Gulf of Aqaba. The present study concerns the application of stacking and persistent scattering of SAR interferometry in order to monitor ground deformation in the southern part of Sharm El-Shiekh area. The specific techniques were applied in order to reduce the influence of atmospheric effects on the ground deformation estimates. For this purpose a total number of 26 ENVISAT ASAR scenes covering the period between 2003 and 2009 were processed and analyzed. Interferometric processing results show both patterns of uplift and downlift in the study area. Specifically an area along the coastline with a N–S direction, corresponding to the build up zone of Sharm El-Sheikh, shows annual average subsidence rates between 5 and 7 mm/yr along the line of sight (LOS). On the contrary, Sharm El-Maya, an inner zone, parallel to the above subsided area; shows maximum slant range uplift of 5 mm/yr. The obtained results of both stacking and persistent scattering indicate that the ground deformation in Sharm El-Sheikh–Ras Nasrani coastal zone is attributed to several effecting factors compromising water pumping, lithology, seismicity, and possible active fracture. The contribution of all these factors is discussed in the context.     

Spatiotemporal relation of RADAR-derived land subsidence with groundwater and seismicity in Semnan—Iran

Natural Hazards - Due to excessive harvesting of underground water resources in many important aquifers inside Iran, ground subsidence is occurring at different speeds. In present study, InSAR...     

Water–gas dynamics and coastal land subsidence over Chioggia Mare field, northern Adriatic Sea

A major development programme comprising 15 gas fields of the northern Adriatic Sea has recently been submitted to the Ministry of the Environment, VIA Committee for the assessment of the environmental impact, by ENI-Agip, the Italian national oil company. One of the largest reservoirs is Chioggia Mare, located about 10 km offshore of the Venetian littoral, with a burial depth of 1000–1400 m. The planned gas production from this field is expected to impact the shoreline stability with a potential threat to the city of Venice, 25 km northwest of the center of Chioggia Mare. To evaluate the risk of anthropogenic land subsidence due to gas withdrawal, a numerical model was developed that predicts the compaction of both the gas-bearing formations and the lateral/bottom aquifer (water drive) during a 13-year producing and a 12-year post-production period, and the transference of the deep compaction to the ground surface. To address the uncertainty of a few important hydromechanical parameters, several scenarios are simulated and the most pessimistic predictions obtained. The modeling results show that at most 1 cm of land subsidence over 25 years may be expected at the city of Chioggia, whereas Venice is not subject to settlement. If aquifer drawdown is mediated by water injection, land subsidence is arrested 5 km offshore, with the Chioggia littoral zone experiencing a rebound of 0.6–0.7 cm. Electronic Publication     

Helium isotopic fingerprints of the heavy land subsidence left in groundwater of the Saga Plain,near Beppu–Shimabara graben,Kyushu, Japan

The Saga Plain is near Beppu–Shimabara graben, a region of potential active volcanism. In the graben, mantle He, which has a high ³He/⁴He ratio of 1.1 × 10⁻⁵, escapes easily from the underlying subduction zone. In groundwater of the Saga Plain, except in the Shiroishi district, this ratio gradually increased as the dissolved He content increased, to a maximum of 5 × 10⁻⁶. In central Shiroishi, however, the ratio reached a minimum of 8.7 × 10⁻⁷ with increasing dissolved He content, suggesting that groundwater in central Shiroishi has selectively accumulated radiogenic He, which has a very low ratio of 1 × 10⁻⁸, rather than reflecting the regional He, which is rich in mantle He. This can be explained if groundwater in Shiroishi has become mixed with fossil pore water drawn from impermeable marine clay aquitard layers. The withdrawal of pore water has also caused severe land subsidence in central Shiroishi.     

The role of the individual producer in driving land change: the case of Santa Cruz, Bolivia, 1986–2006

The “neoliberal period” witnessed some of the largest forest clearing in Latin America, particularly in the relatively untouched eastern lowlands of sub-tropical Bolivia. This paper shows through the use of satellite imagery analysis that ~10,000 km² of forest were cleared during this time period (1986–2006) from an area of forest measuring ~55,000 km². It also shows through the use of semi-structured interviews that the role and the rationale of the individual producer was equally if not more important than structural adjustment policies and their accompanying effects in driving these changes. Producers decisions of how to use the land are influenced by their background and knowledge of production systems (“tradition”), physical and climatic factors, crops which require relatively little input and are easy to cultivate, soil and tillage factors, concerns over quantity of production, and government policies. The importance of this study lies in the fact that the factors which play an important role in land-use and land-cover change are complex and multivariable and include individual decisions of the producer which are sometimes external to the market and other outside influences. This study could possibly serve as an exemplar and a warning that conservationists and policy-makers should take heed of in the future. By focusing solely on macro-economic policies, we can often overlook the individual producer and their decision-making capacity to alter the landscape.     

Types,characteristics, and time–space distribution of molybdenum deposits in China

Molybdenum exploration activity in China has accelerated tremendously during the past decade owing to the continuous, increasing demand for Earth resources. China possesses the largest Mo reserves in the world (exceeding 19.6 Mt). The major ore deposits are of porphyry, porphyry–skarn, skarn, vein, and sedimentary types. Porphyry molybdenum deposits contain 77.5% of the Chinese Mo reserves, with lesser amounts in porphyry–skarns (13%), skarns (5.1%), and veins (4.4%). Exploitation of sedimentary-type molybdenum deposits thus far has been uneconomical. The six Mo provinces are in the Northeast China, Yanliao, Qinling–Dabie, middle–lower Yangtze River Valley, South China, and Sanjiang areas. We recognize six ore-forming periods: (1) Precambrian (>541 Ma), (2) Palaeozoic (541–250 Ma), (3) Triassic (250–200 Ma), (4) Jurassic–Early Cretaceous (190–135 Ma), (5) Cretaceous (135–90 Ma), and (6) Cenozoic (55–12 Ma). The abundance of Mo ore deposits in China reflects the occurrence of multiple periods of tectonism, involving interactions between the Siberian, North China, Yangtze, India, and Palaeo-Pacific plates. Precambrian molybdenum deposits are related to Mesoproterozoic volcanism in an extensional setting. Palaeozoic Cu–Mo deposits are related to calc-alkaline granitic plutons in an island arc or a continental margin setting. Triassic Mo deposits formed in the syn-collision–postcollision tectonic setting between the Siberian and North China plates and between the North China and Yangzi plates. Jurassic–Early Cretaceous molybdenum deposits formed along the eastern margin of Asia and are associated with the palaeo-Pacific plate-subduction tectonic setting. Cretaceous Mo deposits are related to high-K calc-alkaline granitic rocks and formed in a lithospheric thinning setting. Cenozoic molybdenum deposits formed in a collision setting between the Indian and Eurasian continents and the subsequent extensional setting.     

Mining geohazards—land subsidence caused by the dewatering of opencast coal mines: The case study of the Amyntaio coal mine, Florina, Greece

Mining activities impact the nearby environment, causing the so-called mining hazards. The land subsidence phenomena caused by the dewatering of the mines are listed among the mining-induced catastrophic geohazards slowly affecting extensive areas around the opencasts. These large-scale geo-hazards are related to both hydrogeological and geotechnical factors, and they cause irreversible damages. The research presented aims to clarify all the components of the phenomenon and to establish the proper modelling procedure for the study of its mechanism. The site under investigation is the area extending at the west—northwest of the Amyntaio opencast coal mine at Florina Prefecture, Northern Greece. The overexploitation of the aquifers for the protection of the slopes turned the opencast to a large-diameter well, draining the surrounding area. The extensive land subsidence phenomena extend 3–4 km around the mine causing severe damages in two villages. The established results can be used for monitoring and predicting the impact of the particular mining hazard on the natural and human environment, without precluding further exploitation and mining of the energy resources.     

Theory and context in analyzing livelihoods,land use,and land cover: Lessons from Petén,Guatemala

Most studies on the causes of deforestation have sought to link the phenomenon to specific economic, political, or demographic factors, usually through statistical or spatial-statistical modeling. However, generalizations about the link between deforestation and specific variables or classes of variables are of questionable validity. Another approach, one that is receiving growing attention, seeks instead to identify particular contexts or situations, as created by an array of interacting factors, which encourage forms of land use or other economic activity that can generate deforestation pressure. Such an approach was used in this study to explore recent trends and dynamics in the Petén region of northern Guatemala. The research found a number of regional and national scale factors that in combination have led to a process of de-agrarianization and dispossession among smallholders, while large scale, commercial activities in agriculture, ranching and plantation forestry increasingly dominate. Rapid land concentration, in conjunction with limited employment generation through emergent activities, is intensifying pressure on remaining areas of forest. A focus on two distinct areas within Petén reveals how broader-scale trends and features can have differing outcomes at the local level, with contrasting socioeconomic and environmental effects. Finally, the paper explores the implications of recent dynamics in Petén for both policy and theory in relation to deforestation, agrarian change, and regional development. Key factors and questions are highlighted that should be considered when exploring influences on regional socioeconomic and environmental conditions.     

Roles of climate changes and human interventions in land degradation: a case study by net primary productivity analysis in China’s Shiyanghe Basin

The Thornthwaite Memorial, Synthetic, and Carnegie Ames Stanford Approach (CASA) models, with inputs from SPOT-VGT-S10 NDVI data, meteorological data (precipitation, temperature, solar radiation), and land use data were used to estimate the values of net primary productivity (NPP) from 1999 to 2007 in China’s Shiyanghe Basin. The human appropriation of NPP, which represents the difference between potential NPP predicted using the climatic models and actual NPP calculated using the CASA model, served as the indicator of human intervention in the evolution of productivity of the land. Analysis showed that 78.9% (~9,172 km²) of the degradation occurring in the Shiyanghe Basin was caused by human activities versus 15.0% (~1,752 km²) that was caused by climatic factors, whereas 16.9% (~6,404.5 km²) of the vegetation restoration resulted from human activities versus 49.7% (~18,881 km²) that resulted from climate changes. Human activity played a key role in vegetation restoration in the central areas of the basin and in determining land degradation in the southwestern and northeastern areas. In addition, climate significantly controlled the vegetation restoration in the southwestern and northeastern areas and controlled land degradation in the central area.     

Modes,hydrodynamic processes and ecological impacts exerted by river–groundwater transformation in Junggar Basin,China

The hydrodynamic processes and impacts exerted by river–groundwater transformation need to be studied at regional and catchment scale, especially with respect to diverse geology and lithology. This work adopted an integrated method to study four typical modes (characterized primarily by lithology, flow subsystems, and gaining/losing river status) and the associated hydrodynamic processes and ecological impacts in the southern part of Junggar Basin, China. River–groundwater transformation occurs one to four times along the basin route. For mode classification, such transformation occurs: once or twice, controlled by lithological factors (mode 1); twice, impacted by geomorphic features and lithological structures (mode 2); and three or four times, controlled by both geological and lithological structures (modes 3 and 4). Results also suggest: (1) there exist local and regional groundwater flow subsystems at ~400 m depth, which form a multistage nested groundwater flow system. The groundwater flow velocities are 0.1–1.0 and?<0.1 m/day for each of two subsystems; (2) the primary groundwater hydro-chemical type takes on apparent horizontal and vertical zoning characteristics, and the TDS of the groundwater evidently increases along the direction of groundwater flow, driven by hydrodynamic processes; (3) the streams, wetland and terminal lakes are the end-points of the local and regional groundwater flow systems. This work indicates that not only are groundwater and river water derived from the same source, but also hydrodynamic and hydro-chemical processes and ecological effects, as a whole in arid areas, are controlled by stream–groundwater transformation.     

Geology, Geochemistry and Minerogenesis of the Shijuligou Zinc–Copper Deposit in Gansu, China

Abstract: The Shijuligou deposit was separated by an arcuate ductile shear zone cross the center of the deposit region, resulting in the difference between the southern and northern ore bodies. The lead (Pb) isotopic data of ores of the Shijuligou copper deposit have averages of 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb in 17.634, 15.444, and 37.312, respectively. It has been shown that ore-forming metals originated from intrusive and extrusive rocks in the upper part of ophiolites. The sulfur isotopic data of pyrite and chalcopyrite in the northern part change from +7.61‰ to +8.09‰ and +4.95‰ to +8.88‰ in the southern part. Isotopes of δ18O in the Shijuligou copper deposit are between +11.1‰ and +18.6‰, with the calculated δ18OH2O at +0.65‰. It is suggested that the mineralized fluid is a mixture of magma fluid, meteorological water, and seawater through circulating and leaching metals from the volcanic rocks. The zircon uranium-lead (U–Pb) dating of gabbro is 457.9±1.2 Ma, and the lower crossing age of the discordant and concordia curves of pyroxene spilite of zircon is 454±15 Ma. It is indicated that the Shijuligou deposit formed in a new ocean crust (ophiolite) of the back-arc basin in the late Ordovician. Mineralization should occur in the intermittence period after strong volcanic activity, and the age should be the late Ordovician. Moreover, the mineralization of ophiolite-hosted massive sulfide deposits in the ancient orogenic belt of the late Ordovician in the northern Qilian Mountains was controlled by the primary fault/fracture, with the forming of a metallogenic hydrothermal system by a mixture of volcanic magma fluid and seawater, which circularly leached the metallogenic metals from the volcanic rocks, resulting in their accumulation. The ore bodies were transformed with morphology and metallogenic elements. Jasperoid is an important sign for prospecting such deposits. There were many island arcs in the continent of China. This study provides evidence for understanding and exploration of ophiolite-hosted massive sulfide deposits in western China, especially in the area of northern Qilian Mountains.