Using GIS to develop a mobile communications network for disaster-damaged areas     

Youhei Kawamura  Ashraf M. Dewan  Bert Veenendaal  Masahiro Hayashi  Takeshi Shibuya  Itaru Kitahara 《International Journal of Digital Earth》2014,7(4):279-293

Communications network damage resulting from a large disaster causes difficulties in the ability to rapidly understand the current situation and thus make appropriate decisions towards mitigating problems, such as where to send and dispense emergency supplies. The research outlined in this paper focuses on the rapid construction of a network after a disaster occurs. This study suggests ZigBee and geographic information systems (GIS) technologies to resolve these problems and provide an effective communication system. The experimental results of the ZigBee network system are presented, examples are provided of the mapping and analysis undertaken using GIS for the disaster-stricken area of Tsukuba City, Japan, and the communications node arrangements are determined for this region. These results demonstrate the effectiveness of establishing such a communications system for supporting efforts to relieve disaster-damaged areas.  相似文献   

P–T conditions of metabasites within regional metapelites in far-eastern Nepal Himalaya and its tectonic meaning     

Takeshi Imayama 《Swiss Journal of Geoscience》2014,107(1):81-99

Metabasites exposed in far-eastern Nepal provide an important insight into the metamorphic evolution of the Himalayan orogen independent from data obtained on metapelites. The P–T conditions and formation process of mafic granulite intercalated within Early Oligocene migmatites and two amphibolites surrounded by Early Miocene metapelites were inferred from pseudosection modeling and conventional geothermobarometry combined with the occurrences of field and microstructures. A mafic granulite in the Higher Himalaya Crystalline Sequence (HHCS) yields P–T conditions of 6.5–8 kbar, 730–750 °C. The similar peak P–T condition and retrograde path with low P/T gradient of mafic granulite and surrounding migmatite indicate that both rocks were simultaneously metamorphosed and exhumed together along the tectonic discontinuities in the HHCS. In contrast, the P–T conditions (2–5 kbar, 500–600 °C) of highly-deformed amphibolite block above the Main Central Thrust (MCT) records significantly lower pressure than garnet-mica gneisses in the country rock, suggesting that the amphibolite block derived from upper unit of the MCT zone and became tectonically mixed with the gneisses of hanging wall near the surface. An amphibolite lense below the MCT preserves the prograde P–T conditions (6–7.5 kbar, 550–590 °C) of Early Miocene syn-tectonic metamorphism that occurred in the MCT zone. This study indicates the top-to-the south movement of the MCT zone results in the tectonic assembly of rocks with different P–T–t conditions near the MCT.  相似文献   

Hydrochemical and isotopic characteristics of groundwater in the Ndop plain,northwest Cameroon: resilience to seasonal climatic changes     

Mengnjo Jude Wirmvem  Takeshi Ohba  Justice Yuven Suila  Wilson Yetoh Fantong  Nchemty Oscar Bate  Seigo Ooki  Engome Regina Wotany  Asobo Nkengmatia Elvis Asaah  Samuel Ndonwi Ayonghe  Gregory Tanyileke  Joseph Victor Hell 《Environmental Earth Sciences》2014,72(9):3585-3598

Shallow groundwater (>30 mbgl) is an essential source of drinking water to rural communities in the Ndop plain, northwest Cameroon. As a contribution to water management, the effect of seasonal variation on the groundwater chemistry, hydrochemical controls, drinking quality and recharge were investigated during the peaks of the dry (January) and rainy (September) seasons. Field measurements of physical parameters were preceded by sampling 58 groundwater samples during both seasons for major ions and stable isotope analyses. The groundwater, which was barely acidic (mean pH of 6) and less mineralised (TDS < 272 mg/l), showed no significant seasonal variation in temperature, pH and TDS during the two seasons. The order of cation abundance (meq/l) was Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ and Na⁺ > Mg²⁺ > Ca²⁺ > K⁺ in the dry and rainy seasons, respectively, but that of anions ( \( {\text{HCO}}_{3}^{ - } \)  >  \( {\text{NO}}_{3}^{ - } \)  > Cl^? >  \( {\text{SO}}_{4}^{2 - } \)  > F^?) was similar in both seasons. This suggests a negligible effect of seasonal variations on groundwater chemistry. The groundwater, which was CaMgHCO₃ and NaHCO₃, is chemically evolved rainfall (CaMgSO₄Cl) in the area. Silicate mineral dissolution and cation-exchange were the main controls on groundwater chemistry while there was little anthropogenic influence. The major ions and TDS concentrations classified the water as suitable for human consumption as per WHO guidelines. The narrow cluster of δ¹⁸O and δD of same groundwater from both seasons between the δ¹⁸O and δD values of May–June precipitation along the Ndop Meteoric Water Line indicates meteoric origin, rapid recharge (after precipitation) and timing of recharge between May and June rainfall. Diffuse groundwater recharge mainly occurs at low altitudes (<1,400 m asl) within the plain. Besides major ions and TDS, the similar δ¹⁸O and δD of groundwater from both seasons indicate a consistent groundwater recharge and flow pattern throughout the year and resilience to present day short-term seasonal climatic variations. However, controlled groundwater abstraction is recommended given the increasing demand.  相似文献   

Holocene estuarine sediments as a source of arsenic in Pleistocene groundwater in suburbs of Hanoi,Vietnam     

Keisuke Kuroda  Takeshi Hayashi  Ayako Funabiki  An Thuan Do  Vu Duc Canh  Tran Thi Viet Nga  Satoshi Takizawa 《Hydrogeology Journal》2017,25(4):1137-1152

Groundwater pollution by arsenic is a major health threat in suburban areas of Hanoi, Vietnam. The present study evaluates the effect of the sedimentary environments of the Pleistocene and Holocene deposits, and the recharge systems, on the groundwater arsenic pollution in Hanoi suburbs distant from the Red River. At two study sites (Linh Dam and Tai Mo communes), undisturbed soil cores identified a Pleistocene confined aquifer (PCA) and Holocene unconfined aquifer (HUA) as major aquifers, and Holocene estuarine and deltaic sediments as an aquitard layer between the two aquifers. The Holocene estuarine sediments (approximately 25–40 m depth, 9.6–4.8 cal ka BP) contained notably high concentrations of arsenic and organic matter, both likely to have been accumulated by mangroves during the Holocene sea-level highstand. The pore waters in these particular sediments exhibited elevated levels of arsenic and dissolved organic carbon. Arsenic in groundwater was higher in the PCA (25–94 μg/L) than in the HUA (5.2–42 μg/L), in both the monitoring wells and neighboring household tubewells. Elevated arsenic concentration in the PCA groundwater was likely due to vertical infiltration through the arsenic-rich and organic-matter-rich overlying Holocene estuarine sediments, caused by massive groundwater abstraction from the PCA. Countermeasures to prevent arsenic pollution of the PCA groundwater may include seeking alternative water resources, reducing water consumption, and/or appropriate choice of aquifers for groundwater supply.  相似文献