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1.
Tidal inundation mapping under enhanced land subsidence in Semarang,Central Java Indonesia 总被引：3，自引：0，他引：3
Tidal inundation by high tide under enhanced land subsidence is a damaging phenomenon and a major threat to the Semarang urban
area in Indonesia. It impacts on economic activities, as well as the cost of an emergency program and causes interruption
of pubic services, danger of infectious diseases and injury to human lives. This study examines a spatial analysis tool on
the GIS-raster system for the tidal inundation mapping based on the subsidence-benchmark data and modified detail digital
elevation model. Neighborhood operation and iteration model as a spatial analysis tool have been applied in order to calculate
the encroachment of the tidal inundation on the coastal area. The resulting map shows that the tidal flood spreads to the
lowland area and causes the inundation of coastal settlement, infrastructure, as well as productive agricultural land, i.e.,
the fish-pond area. The monitoring of the vulnerable area due to the tidal inundation under the scenario of extended land
subsidence plays an important role in long-term coastal zone management in Semarang. 相似文献
2.
A Geologic Time Scale (GTS2004) is presented that integrates currently available stratigraphic and geochronologic information. Key features of the new scale are outlined, how it was constructed, and how it can be further improved. The accompanying International Stratigraphic Chart, issued under auspices of the International Commission on Stratigraphy (ICS), shows the current chronostratigraphic scale and ages with estimates of uncertainty for all stage boundaries. Special reference is made to the Precambrian part of the time scale, which is coming of age in terms of detail, and to the Neogene portion, which has attained an ultra-high-precision absolute-age calibration. 相似文献
3.
4.
In recent decades, the high population growth has increased the demand for agricultural lands and products. Groundwater offers reliability and flexibility in access to water for irrigation purposes, especially in arid and semi-arid areas, such as Amol-Babol Plain, Iran. However, the quality and quantity of groundwater may not be suitable for irrigation purposes in all areas due to urbanizations, and intensive agricultural and industrial activities. Groundwater suitability zoning for irrigation purposes could be useful to improve water resources and land use planning, mostly in areas with water scarcity. Therefore, a GIS-based indices method is proposed to assess suitable zones for agricultural activities, integrating the irrigation water quality (IWQ) index and hydrogeological factors. IWQ index was utilized to assess groundwater quality based on salinity hazard, infiltration hazard, specific ions, and trace elements hazards, and miscellaneous effects such as pH, bicarbonate, and nitrate. The potential of the aquifer for irrigation water abstraction was investigated using hydrogeological surveys such as slope angle of the plain, hydraulic conductivity, and aquifer thickness. The groundwater suitability index classified most of the study area (more than 90 %) as “excellent” or “good” suitability zones for irrigation purposes. A limited area of around 5.6 % of the total area has moderate suitability for irrigation purposes due to the Caspian Seawater intrusion and the presence of fossil saline water. The proposed methodology provides useful information in order to allow irrigation management to prevent water and soil deterioration. 相似文献
5.
The research was conducted on the outskirts of Yogyakarta City that administratively include three districts of Sleman Regency, namely Depok, Gamping, and Mlati, and three districts of Bantul Regency, namely Kasihan, Sewon, and Banguntapan. It aimed to obtain a deeper understanding on the perceptions of stakeholders on the regional transformation phenomena occurring on the outskirts of Yogyakarta City. This is a qualitative case study research with a single case. The case study research method was selected because the observed phenomenon is contemporary and the analyzed issue is unique. It used a qualitative method with field observations and in-depth interviews to several informants as data acquisition techniques. The informants were stakeholders from state/government, private sector/entrepreneur, academics, and civil society, which were selected using purposive sampling method. The research data processing and analysis included: (1) data reduction, (2) data presentation, and (3) data conclusion. In order to examine the reliability and validity of the data, the research used source triangulation method. The results showed that all stakeholders perceived the regional transformation on the outskirts of Yogyakarta City to have positive and negative consequences on various dimensions. The positive ones were the economic opportunities, generated by the regional transformation process, for both the native people and the migrants. Aside from these positive consequences, the regional transformation on the outskirts of Yogyakarta City also caused negative impacts on the physical, economic, social, and cultural dimensions of the outskirts. 相似文献
6.
Hadmoko Danang Sri de Belizal Edouard Mutaqin Bachtiar Wahyu Dipayana Gilang Arya Marfai Muh Aris Lavigne Franck Sartohadi Junun Worosuprojo Suratman Starheim Colette C. A. Gomez Christopher 《Natural Hazards》2018,94(1):419-444
Following the 2010 VEI 4 eruption of Merapi volcano, more than 250 lahars were triggered during two rainy seasons from October 2010 to March 2012. This high number of post-eruption lahars mainly occurred in the Kali (valley) Putih watershed and was mostly associated with high-magnitude rainstorms. A lahar occurring on January 8, 2011, caused significant damage to homes in several communities, bridges, sabo dams, and agricultural crops. The aims of this contribution are to document the impacts of lahars on the Kali Putih watershed and specifically (1) to analyze the lahar frequency during the period of 1969–2012 on an inter-annual and intra-annual basis and to determine the link between the volume of tephra and the frequency of lahars; (2) to detail the lahar trajectory and channel evolution following the January 8th lahar; (3) to map the spatial distribution of the thickness and geomorphic effects of the lahar deposit; and (4) to determine the impacts of the lahar on the infrastructure (sabo dams and roads) and settlements in the distal area of the volcano. The Kali Putih watershed has experienced 62 lahars, which represent 22% of all lahars triggered on 17 rivers at Merapi between 2010 and 2012. The main geomorphic impacts are: (1) excessive sedimentation in valleys, settlements and agricultural areas; (2) undercutting of the river banks by as much as 50 m, accompanied by channel widening; and (3) abrupt changes in the river channel direction in the distal area (15–20 km downstream of the volcano). About 19 sabo dams were damaged, and 3 were totally destroyed. Over 307 houses were damaged, and the National Road Yogyakarta–Semarang was regularly cut (18 times during approximately 25 days). Although the sabo dams on Kali Putih were originally constructed to protect distal areas from lahar damage, they had little effect on the 2010–2012 rain-triggered lahars. The underlying design of those dams along this river is one of the main reasons for the major destruction in this sector of the volcano’s lower slope. The catch basin capacity of the sabo dam was only 1.75?×?106 m3, whereas the total volume of the 2010–2011 lahars exceeded 5?×?106 m3. In order to prepare for future lahars, the government has invested in significant mitigation measures, ranging from structural approaches (e.g., building new sabo dams and developing an early warning system) to non-structural approaches (e.g., contingency and preparedness planning and hazard education).
相似文献7.
A. Z. Aris M. H. Abdullah B.Sc. M.Sc. Ph.D. A. Ahmed B.Sc. M.Sc. Ph.D. K. K. Woong B.Sc. M.Sc. Ph.D. 《International Journal of Environmental Science and Technology》2007,4(4):441-450
Factor analysis was applied to the hydrochemical data set of Manukan Island in order to extract the principal factors corresponding to the different sources of variation in the hydrochemistry. The application of varimax rotation was to ensure the clear definition of the main sources of variation in the hydrochemistry. The geochemical data of dissolved major, minor and trace constituents in the groundwater samples indicates the main processes responsible for the geochemistry evolution. By using Kaiser normalization, principal factors were extracted from the data for each location. The analysis reveals that there are four sources of solutes: (1) seawater intrusion; (2) leaching process of underlying rock mediated by pH; (3) minerals weathering process and (4) dissolution of carbonate minerals characterized by high loadings of Ca, Zn and Mg. Such processes are dominated by the significant role of anthropogenic impact from the over abstraction of fresh water from the aquifer. Those factors contributed to the changes of the groundwater geochemistry behavior explain the effect of rising extraction of freshwater from the aquifer. 相似文献
8.
A continuous simulation of global ice volume over the past 1 million years with 3-D ice-sheet models
B. de Boer R. S. W. van de Wal L. J. Lourens R. Bintanja T. J. Reerink 《Climate Dynamics》2013,41(5-6):1365-1384
Sea-level records show large glacial-interglacial changes over the past million years, which on these time scales are related to changes of ice volume on land. During the Pleistocene, sea-level changes induced by ice volume are largely caused by the waxing and waning of the large ice sheets in the Northern Hemisphere. However, the individual contributions of ice in the Northern and Southern Hemisphere are poorly constrained. In this study, for the first time a fully coupled system of four 3-D ice-sheet models is used, simulating glaciations on Eurasia, North America, Greenland and Antarctica. The ice-sheet models use a combination of the shallow ice and shelf approximations to determine sheet, shelf and sliding velocities. The framework consists of an inverse forward modelling approach to derive a self-consistent record of temperature and ice volume from deep-sea benthic δ18O data over the past 1 million years, a proxy for ice volume and temperature. It is shown that for both eustatic sea level and sea water δ18O changes, the Eurasian and North American ice sheets are responsible for the largest part of the variability. The combined contribution of the Antarctic and Greenland ice sheets is about 10 % for sea level and about 20 % for sea water δ18O during glacial maxima. However, changes in interglacials are mainly caused by melt of the Greenland and Antarctic ice sheets, with an average time lag of 4 kyr between melt and temperature. Furthermore, we have tested the separate response to changes in temperature and sea level for each ice sheet, indicating that ice volume can be significantly influenced by changes in eustatic sea level alone. Hence, showing the importance of a simultaneous simulation of all four ice sheets. This paper describes the first complete simulation of global ice-volume variations over the late Pleistocene with the possibility to model changes above and below present-day ice volume, constrained by observations of benthic δ18O proxy data. 相似文献
9.
Joint variable spatial downscaling 总被引：1，自引：0，他引：1
Joint Variable Spatial Downscaling (JVSD), a new statistical technique for downscaling gridded climatic variables, is developed to generate high resolution gridded datasets for regional watershed modeling and assessments. The proposed approach differs from previous statistical downscaling methods in that multiple climatic variables are downscaled simultaneously and consistently to produce realistic climate projections. In the bias correction step, JVSD uses a differencing process to create stationary joint cumulative frequency statistics of the variables being downscaled. The functional relationship between these statistics and those of the historical observation period is subsequently used to remove GCM bias. The original variables are recovered through summation of bias corrected differenced sequences. In the spatial disaggregation step, JVSD uses a historical analogue approach, with historical analogues identified simultaneously for all atmospheric fields and over all areas of the basin under study. Analysis and comparisons are performed for 20th Century Climate in Coupled Models (20C3M), broadly available for most GCMs. The results show that the proposed downscaling method is able to reproduce the sub-grid climatic features as well as their temporal/spatial variability in the historical periods. Comparisons are also performed for precipitation and temperature with other statistical and dynamic downscaling methods over the southeastern US and show that JVSD performs favorably. The downscaled sequences are used to assess the implications of GCM scenarios for the Apalachicola-Chattahoochee-Flint river basin as part of a comprehensive climate change impact assessment. 相似文献
10.
Simon Johnston Aris Karastergiou Dipanjan Mitra Yashwant Gupta 《Monthly notices of the Royal Astronomical Society》2008,388(1):261-274
We have observed a total of 67 pulsars at five frequencies ranging from 243 to 3100 MHz. Observations at the lower frequencies were made at the Giant Metre-Wave Telescope in India and those at higher frequencies at the Parkes Telescope in Australia. We present profiles from 34 of the sample with the best signal-to-noise ratio and the least scattering. The general 'rules' of pulsar profiles are seen in the data; profiles get narrower, the polarization fraction declines and outer components become more prominent as the frequency increases. Many counterexamples to these rules are also observed, and pulsars with complex profiles are especially prone to rule breaking. We hypothesize that the location of pulsar emission within the magnetosphere evolves with time as the pulsar spins down. In highly energetic pulsars, the emission comes from a confined range of high altitudes, in the middle range of spin down energies the emission occurs over a wide range of altitudes whereas in pulsars with low spin-down energies it is confined to low down in the magnetosphere. 相似文献