Customary Management System of Irrigation Ponds in Japan-a Case Study in a Globally Important Agricultural Heritage Systems (GIAHS) Site of Noto Island,Ishikawa Prefecture     

QIU Zhenmian  CHEN Bixia  NAKAMURA Koji 《资源与生态学报(英文版)》2016,7(3):205-210

Recent research has showed increasing interest at the vital role of irrigation ponds that plays at biodiversity conservation, and provides ecological functions at a wide range. However, many irrigation ponds were abolished due to the economic and societal transformation in the rural. In particular, small-scale ponds were abolished and rebuilt to other public uses based on the consensus building process among the community. At the same time, civil organizations also launched initiatives to conserve irrigation ponds for its ecological significance or landscape scenery. However, study pertinent to the small scale ponds in the rural setting is largely neglected. This research aims at revealing the current situation of the utilization and management of small irrigation ponds using a case study of Noto Island in Ishikawa Prefecture. It was found that irrigation ponds are still under the traditional co-management of rural community. The most important finding in this study is that the traditional management of pond water use largely contributes to mitigate the harvest loss from natural disasters such as drought in the face of extreme climate. However, irrigation ponds are facing the threat of degradation due to the sharp decrease of farm population and the existing large number of part time farmers. Therefore, the small scale irrigation ponds and pertinent management and water use allotment should be revalued for its functions at a wide range from the biological and ecological functions and human knowledge system to mitigate disaster threats.  相似文献   

Opening and closing process of the Paleo-Tethys in Northern Thailand     

Hidetoshi HARA  Koji WAKITA  Jun-ichiro KURODA  Toshiyuki KURIHARA  Katsumi UENO  Yoshihito KAMATA  Ken-ichiro HISADA  Punya CHARUSIRI  Thasinee CHAROENTITIRAT  Pol CHAODUMRONG 《地球学报》2009,30(Z1):12-12

The Paleo-Tethys formed a large ocean basin that existed between Laurasia and Gondwana during Late Paleozoic to Early Mesozoic times. It opened in the Early Devonian by the rifting of Gondwanaland and closed at around latest Triassic time by the collision of the Cimmerian continent to Laurasia (Metcalfe, 1999). We reconstructed opening and closing process of the Paleo-Tethys in Northern Thailand.  相似文献   

Late Pleistocene and Holocene vegetation and climate records from Lake Kotokel, central Baikal region     

Koji Shichi  Hikaru Takahara  Sergey K. Krivonogov  Elena V. Bezrukova  Kenji Kashiwaya  Akihide Takehara  Toshio Nakamura 《Quaternary International》2009,205(1-2):98

Climatically driven Late Pleistocene and Holocene vegetation changes were reconstructed based on pollen records from the sediments of Lake Kotokel and Cheremushka Bog, located on the eastern shore of Lake Baikal. The described paleoenvironmental record has higher resolution than records collected from Lake Baikal and unites individual events identified in prior studies of bottom and onshore cores. Remarkable shifts in landscapes and expansions of index plants are as follows. Forest tundra and/or forest steppe landscape with birch, spruce, Artemisia, and Poaceae prevailed at ca. 50–25 ¹⁴C kyr BP. Tundra and/or steppe vegetation dominated by Artemisia and Poaceae was typical for the Last Glacial Maximum. The expansion of shrub birch and willow occurred at ca. 15.5 ¹⁴C kyr BP. Two peaks of spruce expansion at ca. 47.5–42.4 ¹⁴C kyr BP (Karginian time) and at ca. 14.5–13 ka (Bølling-Allerød warm intervals) suggest that the condition were more humid than today. A slight increase in Artemisia at ca. 11–10.5 ¹⁴C kyr BP (13–12 ka) was indicative of the Younger Dryas event. An expansion of birch forests with fir at ca. 12–6.4 ka suggests higher humidity. The currently dominant Scots and Siberian pine forests with birch expanded since 6.4 ka.  相似文献   

Upwelling in the Alaskan Beaufort Sea: Atmospheric forcing and local versus non-local response     

Robert S. Pickart  Michael A. Spall  G.W.K. Moore  Thomas J. Weingartner  Rebecca A. Woodgate  Knut Aagaard  Koji Shimada 《Progress in Oceanography》2011,88(1-4):78-100

The spin up and relaxation of an autumn upwelling event on the Beaufort slope is investigated using a combination of oceanic and atmospheric data and numerical models. The event occurred in November 2002 and was driven by an Aleutian low storm. The wind field was strongly influenced by the pack-ice distribution, resulting in enhanced winds over the open water of the Chukchi Sea. Flow distortion due to the Brooks mountain range was also evident. Mooring observations east of Barrow Canyon show that the Beaufort shelfbreak jet reversed to the west under strong easterly winds, followed by upwelling of Atlantic Water onto the shelf. After the winds subsided a deep eastward jet of Atlantic Water developed, centered at 250 m depth. An idealized numerical model reproduces these results and suggests that the oceanic response to the local winds is modulated by a propagating signal from the western edge of the storm. The disparity in wave speeds between the sea surface height signal—traveling at the fast barotropic shelf wave speed—versus the interior density signal—traveling at the slow baroclinic wave speed—leads to the deep eastward jet. The broad-scale response to the storm over the Chukchi Sea is investigated using a regional numerical model. The strong gradient in windspeed at the ice edge results in convergence of the offshore Ekman transport, leading to the establishment of an anti-cyclonic gyre in the northern Chukchi Sea. Accordingly, the Chukchi shelfbreak jet accelerates to the east into the wind during the storm, and no upwelling occurs west of Barrow Canyon. Hence the storm response is fundamentally different on the Beaufort slope (upwelling) versus the Chukchi slope (no upwelling). The regional numerical model results are supported by additional mooring data in the Chukchi Sea.  相似文献   

Study on the selection of unsaturated flow model for the different types of soil and soft rock   总被引：1，自引：1，他引：0  

Sajeewani Rajika Amarasinghe  Kunio Watanabe  Koji Ishiyama 《Environmental Earth Sciences》2011,64(7):1795-1805

Precise estimation of unsaturated hydraulic properties of porous media is indispensable in various study areas, such as analyzing the moisture flow, the drying process occurring from the surface, and the pollutant migration beneath the ground surface. Although many empirical/theoretical models describing the unsaturated hydraulic properties have been proposed by several previous researchers, the best model for the different types of soil/rock may not be identical. Thus, the model selection process and the estimation technique of the parameters included in the models should be developed. In the present study, the inverse technique based on the transient evaporation change was investigated to select the model and estimate the model parameters. The experimental work was based on a relatively low permeable soft rock and a relatively high permeable sandy soil (Toyoura standard sand). Experimental equipment was developed to precisely measure the evaporation rate for the high permeable sandy soil. The Genetic Algorithm (GA) was adopted in the inverse technique as an optimization tool. In order to simplify the problem, only the drying process from the saturated condition was considered. It was established that the information concerning the transient evaporation change could be used for the model selection and parameter estimation. Further, the saturation distribution could be used for the selection of the models. The present study provides important information for the development of the model selection process.  相似文献   

Importance of intracellular Fe pools on growth of marine diatoms by using unialgal cultures and on the Oyashio region phytoplankton community during spring     

Koji Sugie  Kenshi Kuma  Satoshi Fujita  Satomi Ushizaka  Koji Suzuki  Tsutomu Ikeda 《Journal of Oceanography》2011,67(2):183-196

We report on the ability for luxury Fe uptake and the potential for growth utilizing intracellular Fe pools for 4 coastal centric diatom isolates and in situ phytoplankton assemblages, mainly composed of diatoms. Iron uptake of the diatom isolates and natural phytoplankton assemblages in the Oyashio region during spring blooms were prevented by adding hydroxamate siderophore desferrioxamine B (DFB). After the addition of DFB, intracellular Fe in the diatom isolates supported 2.4–4.2 cell divisions with 1.2–2.6 Chl a doublings. The intracellular Fe was primarily used for cell generation rather than Chl a production, leading to a reduction in the Chl a cell quota in the Fe-starved cells with time. The metabolic properties of the Fe-starved cells with their cell morphologies were different among species or genera. An on-deck incubation experiment also exhibited 1.9 cell divisions and 0.81 Chl a doublings of phytoplankton after the addition of DFB, also indicating the preference of cell generation over Chl a production. A decrease in the level of cellular Chl a, a main light-harvesting pigment in Fe-starved diatoms, may become a superior survival strategy to protect the cells from high irradiance that can cause photo-oxidative damages through photosynthesis. Such relatively low-Fe with high-light conditions could often occur in surface waters of the Oyashio region from spring to summer.  相似文献   

Japan’s Nation-Wide Electronic Geotechnical Database Systems by Japanese Geotechnical Society     

Hiroaki Todo  Koji Yamamoto  Mamoru Mimura  Susumu Yasuda 《Geotechnical and Geological Engineering》2013,31(3):941-963

On October 15, 2010, the Japanese Geotechnical Society (JGS) announced the public release of ‘Nation-wide Electronic Geotechnical Database Systems,’ which provides geotechnical information to the public on the internet. The information the system provides is a collection of ground models at 250 m by 250 m in plan built by using data from various geotechnical information databases. The paper first describes historical development of the geotechnical information databases in Japan, and introduces a 5-year project, ‘Integrated Geophysical and Geological Information Database in Japan,’ led by the National Research Institute for Earth Science and Disaster Prevention (NIED), and participated by the JGS. The paper then presents the JGS’ ‘Nation-wide Electronic Geotechnical Database Systems,’ and describes why such system was proposed and built, followed by the presentation of the examples for possible application of the system.  相似文献   

Three-Dimensional Subsurface Structure Model of Kansai International Airport by Integration of Borehole Data and Seismic Profiles     

Naoto Inoue  Naoko Kitada  Keiji Takemura  Koji Fukuda  Tsuyoshi Emura 《Geotechnical and Geological Engineering》2013,31(3):881-890

The three-dimensional subsurface structure model around Kansai International Airport (KIX) has been developed based on the geologically and geotechnically investigated results of a large amount of borehole data for estimation of subsidence. The model consists of the alternation of marine clay and coarse deposits. The many seismic surveys and borehole drillings were carried out around the KIX before the constructing the airport. The stratigraphy of the model was renewed by the KIX18-1, which was about 1,300 m long drilling core and was drilled near the 2nd runway of the KIX from 2006 to 2007. In this study, the subsurface geological model was revised by integration of renewed borehole data and seismic profiles to incorporate complex warping structure and heterogenic lateral variation.  相似文献   

Foraminiferal evidence of submarine sediment transport and deposition by backwash during the 2004 Indian Ocean tsunami     

Daisuke  Sugawara  Koji  Minoura  Naoki  Nemoto  Shinji  Tsukawaki  Kazuhisa  Goto  Fumihiko  Imamura 《Island Arc》2009,18(3):513-525

Micropaleontological analysis of nearshore to offshore sediments recovered from the southwestern coast of Thailand was performed to clarify the submarine processes of sediment transport and deposition during the 2004 Indian Ocean tsunami. The distribution pattern of benthic foraminifers showed seaward migration after the tsunami event. Agglutinated foraminifers, which are characteristic of an intertidal brackish environment, were identified in the post-tsunami samples from foreshore to offshore zones. These suggest that sediments originally distributed in foreshore to nearshore zones were transported offshore due to the tsunami backwash. On the other hand, the distribution pattern of planktonic and benthic species living in offshore zones showed slight evidence of landward migration by the tsunami. This suggests that landward redistribution of sediments by the tsunami run-up did not occur in the offshore seafloor of the study area. Our results and a review of previous studies provide an interpretation of submarine sedimentation by tsunamis. It is possible that tsunami backwashes induce sediment flows that transport a large amount of coastal materials seaward. Thus, traces of paleotsunami backwashes can be identified in offshore sedimentary environments as the accumulation of allochthonous materials. This can be recognized as changes in benthic foraminiferal assemblages.  相似文献   

Secondary remanent magnetization carried by magnetite inclusions in silicates: a comparative study of unremagnetized and remagnetized granites     

Yo-ichiro Otofuji  Koji Uno  Takahiro Higashi  Tomomichi Ichikawa  Tsuyoshi Ueno  Toshiaki Mishima  Takaaki Matsuda 《Earth and Planetary Science Letters》2000,180(3-4):271-285

Magnetic carriers in remagnetized Cretaceous granitic rocks of northeast Japan were studied using paleomagnetism, rock magnetism, optical microscopy and scanning electron microscopy (SEM) by comparison with unremagnetized granitic rocks. The natural remanent magnetization (NRM) of the remagnetized rocks is strong (0.3–1.7 A/m) and shows a northwesterly direction with moderate inclination (NW remanence), whereas the unremagnetized rocks preserve weak NRM (<0.5 A/m) with westerly and shallow direction (W remanence). Although thermal demagnetization shows that both NRMs are carried by magnetite, the remagnetized rocks reveal a higher coercivity with respect to alternating field demagnetization (20 mT相似文献