start-ver=1.4 cd-journal=joma no-vol=14 cd-vols= no-issue=1 article-no= start-page=17 end-page=22 dt-received= dt-revised= dt-accepted= dt-pub-year=2009 dt-pub=20090316 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Capillary cut design for soil-groundwater salinity control en-subtitle= kn-subtitle= en-abstract= kn-abstract=Soil-groundwater salinity issues have assumed a worldwide dimension. It is believed that when groundwater level is less than 2 m there is the possibility of salinity transfer between the soil and groundwater due to factors such as capillary forces. One-dimensional column tests were conducted in the laboratory to find a suitable capillary cut design. The capillary cut material comprised a 20 cm thick 2–4.7 mm and a combination of 2–4.7 mm and 9.5–19 mm gravel material. In all, four different designs were tested by compacting Oji sand in the various columns. Groundwater level of 0.75 m from the top was maintained while salt solution of 10% concentration was allowed to flow under capillary forces through the columns. The water content in the columns were monitored using frequency domain reflectrometry-vector analyzer (FDR-V) after which soil samples from 10 m interval in each column was taken for electrical conductivity measurements. The results showed that 5 cm thick, 2–4.7 mm gravel sandwiching coarser material (e.g. 5 cm thick 9.5–19 mm or 10 cm thick 9.5–19 mm gravel material) proved to be very useful design to cut capillarity. en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=AkudagoJohn Apambilla kn-aut-sei=Akudago kn-aut-mei=John Apambilla aut-affil-num=1 ORCID= en-aut-name=NishigakiMakoto en-aut-sei=Nishigaki en-aut-mei=Makoto kn-aut-name=西垣誠 kn-aut-sei=西垣 kn-aut-mei=誠 aut-affil-num=2 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=ChegbelehLarry Pax kn-aut-sei=Chegbeleh kn-aut-mei=Larry Pax aut-affil-num=3 ORCID= en-aut-name=KomatsuMitsuru en-aut-sei=Komatsu en-aut-mei=Mitsuru kn-aut-name=小松満 kn-aut-sei=小松 kn-aut-mei=満 aut-affil-num=4 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=AlimMd. Abdul kn-aut-sei=Alim kn-aut-mei=Md. Abdul aut-affil-num=5 ORCID= affil-num=1 en-affil= kn-affil=岡山大学 affil-num=2 en-affil= kn-affil=岡山大学 affil-num=3 en-affil= kn-affil=岡山大学 affil-num=4 en-affil= kn-affil=岡山大学 affil-num=5 en-affil= kn-affil=岡山大学 en-keyword=soil-groundwater salinity kn-keyword=soil-groundwater salinity en-keyword=capillary cut kn-keyword=capillary cut en-keyword=filter media design kn-keyword=filter media design END start-ver=1.4 cd-journal=joma no-vol=14 cd-vols= no-issue=1 article-no= start-page=23 end-page=28 dt-received= dt-revised= dt-accepted= dt-pub-year=2009 dt-pub=20090316 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Laboratory Investigation of Ethanol/Bentonite Slurry Grouting into Rock Fractures: Preliminary Resalts en-subtitle= kn-subtitle= en-abstract= kn-abstract=During underground space development, groundwater seepage mostly occurs which may seriously affect the stability of deep excavations as well as retard progress of construction. For smooth progress of work, effective construction and operation of a disposal facility for high level radioactive waste (HLW), it is important to control seepage into excavations by sealing off fractures or fissures and excavation disturbed zones (EDZ) to control groundwater inflow during the construction phase of such a facility. In this study, a series of experiments were conducted on ethanol/bentonite slurries in the laboratory with the aim of determining the effect of a hydrophilic solvent such as ethanol on the hydraulic and injection characteristic of bentonite slurry for the sealing of fissures to control ground water seepage during the construction phase of a repository. Preliminary results revealed ethanol/bentonite slurry as an effective grouting material capable of penetrating micro fractures (100μm or less) and with the permeability of the grouted medium being as low as 10E-7cm/s. The results also show that the effectiveness and efficiency of grouting is dependent on the type of injection and fissure size. Dynamic injection was observed to be efficient as it was able to inject high dense slurry. en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=ChegbelehLarry Pax kn-aut-sei=Chegbeleh kn-aut-mei=Larry Pax aut-affil-num=1 ORCID= en-aut-name=NishigakiMakoto en-aut-sei=Nishigaki en-aut-mei=Makoto kn-aut-name=西垣誠 kn-aut-sei=西垣 kn-aut-mei=誠 aut-affil-num=2 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=AkudagoJohn Apambilla kn-aut-sei=Akudago kn-aut-mei=John Apambilla aut-affil-num=3 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=AlimMd. Abdul kn-aut-sei=Alim kn-aut-mei=Md. Abdul aut-affil-num=4 ORCID= en-aut-name=KomatsuMitsuru en-aut-sei=Komatsu en-aut-mei=Mitsuru kn-aut-name=小松満 kn-aut-sei=小松 kn-aut-mei=満 aut-affil-num=5 ORCID= affil-num=1 en-affil= kn-affil=岡山大学 affil-num=2 en-affil= kn-affil=岡山大学 affil-num=3 en-affil= kn-affil=岡山大学 affil-num=4 en-affil= kn-affil=岡山大学 affil-num=5 en-affil= kn-affil=岡山大学 en-keyword=Dynamic injection kn-keyword=Dynamic injection en-keyword=permeability kn-keyword=permeability en-keyword=swelling kn-keyword=swelling en-keyword=bentonite kn-keyword=bentonite en-keyword=clay kn-keyword=clay END start-ver=1.4 cd-journal=joma no-vol=14 cd-vols= no-issue=1 article-no= start-page=13 end-page=16 dt-received= dt-revised= dt-accepted= dt-pub-year=2009 dt-pub=20090316 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Determination of Soil-Water Characteristic Curves of Unsaturated Sandy Soils Using Membrane Filter with Stainless Wire Mesh en-subtitle= kn-subtitle= en-abstract= kn-abstract=Soil-water characteristic curve (SWCC) is an important soil function in an unsaturated soil mechanics field for design and analyses of any unsaturated earth structures. Determination of SWCC is not easy and more so time consuming. Generally, ceramic disc with high air-entry value has been used in the pressure plate apparatus for this purpose by many people. Now-a-days membrane filter is being used as a suitable alternative to ceramic disc. However, experience shows, it has disadvantage of breakage after one time use especially with coarse grain soils (sandy soils). In this study, membrane filter with stainless wire mesh was used to solve this problem and the SWWC was compared with the results obtained without wire mesh. Results showed that membrane filter with stainless wire mesh can be used to determine the SWCC for coarse grain soils. en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=AlimMd. Abdul kn-aut-sei=Alim kn-aut-mei=Md. Abdul aut-affil-num=1 ORCID= en-aut-name=NishigakiMakoto en-aut-sei=Nishigaki en-aut-mei=Makoto kn-aut-name=西垣誠 kn-aut-sei=西垣 kn-aut-mei=誠 aut-affil-num=2 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=ChegbelehLarry Pax kn-aut-sei=Chegbeleh kn-aut-mei=Larry Pax aut-affil-num=3 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=AkudagoJohn Apambilla kn-aut-sei=Akudago kn-aut-mei=John Apambilla aut-affil-num=4 ORCID= en-aut-name=KomatsuMitsuru en-aut-sei=Komatsu en-aut-mei=Mitsuru kn-aut-name=小松満 kn-aut-sei=小松 kn-aut-mei=満 aut-affil-num=5 ORCID= affil-num=1 en-affil= kn-affil=岡山大学 affil-num=2 en-affil= kn-affil=岡山大学 affil-num=3 en-affil= kn-affil=岡山大学 affil-num=4 en-affil= kn-affil=岡山大学 affil-num=5 en-affil= kn-affil=岡山大学 en-keyword=SWCC kn-keyword=SWCC en-keyword=Unsaturated sandy soils kn-keyword=Unsaturated sandy soils en-keyword=Membrane filter kn-keyword=Membrane filter en-keyword=Stainless wire mesh kn-keyword=Stainless wire mesh END start-ver=1.4 cd-journal=joma no-vol=13 cd-vols= no-issue=1 article-no= start-page=1 end-page=5 dt-received= dt-revised= dt-accepted= dt-pub-year=2008 dt-pub=200803 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Concepts of Repository and the Functions of Bentonite in Repository Environments: A State – of – the – art review en-subtitle= kn-subtitle= en-abstract= kn-abstract=In an effort to secure the comfort of all aspect of life and security through electricity production, research, nuclear weapons production and medical uses, radioactive waste is being generated throughout the world as a result. Without pro – active management and protection, the hazardous nature of radioactive materials can pose serious threats to human health and the environment. A waste containment or disposal facility is required to isolate the waste from man and the biosphere to avoid any undue radiation exposure. Deep geological repository or disposal facility is considered as an effective way to isolate high level radioactive waste, HLW from the human environment, for which a multi – barrier system plays a very significant role. In this paper, literature collection was carried out, aimed to overview the present knowledge about the concepts of repository for HLW and to identify technologies that are currently available in the nuclear industry worldwide and the current state of barrier technologies for hazardous waste sites. en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=ChegbelehLarry Pax kn-aut-sei=Chegbeleh kn-aut-mei=Larry Pax aut-affil-num=1 ORCID= en-aut-name=NishigakiMakoto en-aut-sei=Nishigaki en-aut-mei=Makoto kn-aut-name=西垣誠 kn-aut-sei=西垣 kn-aut-mei=誠 aut-affil-num=2 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=AkudagoJohn Apambilla kn-aut-sei=Akudago kn-aut-mei=John Apambilla aut-affil-num=3 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=AlimMd. Abdul kn-aut-sei=Alim kn-aut-mei=Md. Abdul aut-affil-num=4 ORCID= en-aut-name=KomatsuMitsuru en-aut-sei=Komatsu en-aut-mei=Mitsuru kn-aut-name=小松満 kn-aut-sei=小松 kn-aut-mei=満 aut-affil-num=5 ORCID= affil-num=1 en-affil= kn-affil=World Vision Ghana Rural Water Project affil-num=2 en-affil= kn-affil=岡山大学 affil-num=3 en-affil= kn-affil=World Vision Ghana Rural Water Project affil-num=4 en-affil= kn-affil=岡山大学 affil-num=5 en-affil= kn-affil=岡山大学 en-keyword=repository kn-keyword=repository en-keyword=bentonite kn-keyword=bentonite en-keyword=radioactive waste kn-keyword=radioactive waste en-keyword=swelling kn-keyword=swelling en-keyword=buffer and backfill materials kn-keyword=buffer and backfill materials END start-ver=1.4 cd-journal=joma no-vol=13 cd-vols= no-issue=1 article-no= start-page=63 end-page=66 dt-received= dt-revised= dt-accepted= dt-pub-year=2008 dt-pub=200803 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=State of the Art on Filter Design and Particle Clogging; and Proposed New Numerical Approach to Redesign en-subtitle= kn-subtitle= en-abstract= kn-abstract=Filters are essential in the design of embankments/dams, drains and wells for water and oil supplies. As a result of these functions, filter use is increasing. In order to use the required filter, various empirical relations have been given based on mathematical and field experience. However, these guidelines have not worked to perfection considering the fact that clogging within the filter face is a serious challenge. A short review on filter design criteria is given in this script coupled with a numerical formulation to propose the design limits. en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=Akudago ApambillaJohn kn-aut-sei=Akudago Apambilla kn-aut-mei=John aut-affil-num=1 ORCID= en-aut-name=NishigakiMakoto en-aut-sei=Nishigaki en-aut-mei=Makoto kn-aut-name=西垣誠 kn-aut-sei=西垣 kn-aut-mei=誠 aut-affil-num=2 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=Chegbeleh LarryPax kn-aut-sei=Chegbeleh Larry kn-aut-mei=Pax aut-affil-num=3 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=AlimMd. Abdul kn-aut-sei=Alim kn-aut-mei=Md. Abdul aut-affil-num=4 ORCID= en-aut-name=KomatsuMitsuru en-aut-sei=Komatsu en-aut-mei=Mitsuru kn-aut-name=小松満 kn-aut-sei=小松 kn-aut-mei=満 aut-affil-num=5 ORCID= en-aut-name=KumamaruKoji en-aut-sei=Kumamaru en-aut-mei=Koji kn-aut-name=熊丸耕志 kn-aut-sei=熊丸 kn-aut-mei=耕志 aut-affil-num=6 ORCID= affil-num=1 en-affil= kn-affil=World Vision Ghana Rural Water Project affil-num=2 en-affil= kn-affil=岡山大学 affil-num=3 en-affil= kn-affil=World Vision Ghana Rural Water Project affil-num=4 en-affil= kn-affil=岡山大学 affil-num=5 en-affil= kn-affil=岡山大学 affil-num=6 en-affil= kn-affil=岡山大学 en-keyword=filter kn-keyword=filter en-keyword=particle clogging kn-keyword=particle clogging en-keyword=filter classification kn-keyword=filter classification en-keyword=numerical model equation kn-keyword=numerical model equation en-keyword=force of attraction kn-keyword=force of attraction END start-ver=1.4 cd-journal=joma no-vol=11 cd-vols= no-issue=1 article-no= start-page=57 end-page=64 dt-received= dt-revised= dt-accepted= dt-pub-year=2006 dt-pub=20060315 dt-online= en-article= kn-article= en-subject= kn-subject= en-title=Measuring Method of Water Content for High compacted Bentonite Block by using Frequency Domain Reflectometry kn-title=FDR法による高配合圧縮ベントナイト系材料の水分量測定方法に関する研究 en-subtitle= kn-subtitle= en-abstract= kn-abstract=In the high-level radioactive waste disposal project, in order to know the infiltration behavior, it have to be examined that the bentonite buffer material is used as a barrier, and the measuring device of moisture with the high accuracy is required. In this study it is discussed the usefulness for Frequency Domain Refrectometry (FDR) method through the measuring dielectric constant and making the calibration curve for the several kinds of bentonite material block (pure and silica sand mixing). en-copyright= kn-copyright= en-aut-name=NishigakiMakoto en-aut-sei=Nishigaki en-aut-mei=Makoto kn-aut-name=西垣誠 kn-aut-sei=西垣 kn-aut-mei=誠 aut-affil-num=1 ORCID= en-aut-name=KomatsuMitsuru en-aut-sei=Komatsu en-aut-mei=Mitsuru kn-aut-name=小松満 kn-aut-sei=小松 kn-aut-mei=満 aut-affil-num=2 ORCID= en-aut-name=ChijimatsuMasakazu en-aut-sei=Chijimatsu en-aut-mei=Masakazu kn-aut-name=千々松正和 kn-aut-sei=千々松 kn-aut-mei=正和 aut-affil-num=3 ORCID= affil-num=1 en-affil= kn-affil=岡山大学 affil-num=2 en-affil= kn-affil=岡山大学 affil-num=3 en-affil= kn-affil=間組技術･環境本部原子力部 en-keyword=Measuring syatem kn-keyword=Measuring syatem en-keyword=Bentonite kn-keyword=Bentonite en-keyword=Volumetric mousture content kn-keyword=Volumetric mousture content en-keyword=Frequency domain reflectometry kn-keyword=Frequency domain reflectometry END start-ver=1.4 cd-journal=joma no-vol=11 cd-vols= no-issue=1 article-no= start-page=51 end-page=55 dt-received= dt-revised= dt-accepted= dt-pub-year=2006 dt-pub=20060315 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Laboratory Verification of a Proposed New Method to Determine the In-Situ Effective Porosity of Unsaturated Soil en-subtitle= kn-subtitle= en-abstract= kn-abstract=A laboratory validation of a proposed new method of determining the in-situ effective porosity of unsaturated soils was carried out on unsaturated river sand. The proposed method consists of boring a small diameter hole into the soil and inserting an Amplitude Domain Reflectometry (ADR) probe at the bottom part of the hole. Water is supplied into the hole till saturation and later de-saturated. The water content with time is determined from the ADR probe voltage potential readings. The effective porosity is determined from the difference between the saturated and de-saturated water contents. However, in the laboratory, the water is supplied through the top and bottom parts of the sample. From the experiments the obtained effective porosity ranged from 0.28 to 0.29 for wetting from the top with an average of 0.287 and 0.29 to 0.30 for wetting from the bottom with an average of 0.293. The determined effective porosity ranged from 71.7-73.3% of the real initial porosity of 0.40 of the river sand. The maximum attained degree of saturation during the experiment was 91%. The results indicated that the method will be suitable and useful in determining the effective porosity of medium grained unsaturated soils. en-copyright= kn-copyright= en-aut-name=NishigakiMakoto en-aut-sei=Nishigaki en-aut-mei=Makoto kn-aut-name=西垣誠 kn-aut-sei=西垣 kn-aut-mei=誠 aut-affil-num=1 ORCID= en-aut-name=KomatsuMitsuru en-aut-sei=Komatsu en-aut-mei=Mitsuru kn-aut-name=小松満 kn-aut-sei=小松 kn-aut-mei=満 aut-affil-num=2 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=AkudagoJohn Apambilla kn-aut-sei=Akudago kn-aut-mei=John Apambilla aut-affil-num=3 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=ShinshiYoshihide kn-aut-sei=Shinshi kn-aut-mei=Yoshihide aut-affil-num=4 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=KawakamiKenji kn-aut-sei=Kawakami kn-aut-mei=Kenji aut-affil-num=5 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=KumamaruKoji kn-aut-sei=Kumamaru kn-aut-mei=Koji aut-affil-num=6 ORCID= affil-num=1 en-affil= kn-affil=岡山大学 affil-num=2 en-affil= kn-affil=岡山大学 affil-num=3 en-affil= kn-affil=岡山大学 affil-num=4 en-affil= kn-affil=岡山大学 affil-num=5 en-affil= kn-affil=岡山大学 affil-num=6 en-affil= kn-affil=岡山大学 en-keyword=Underground dam kn-keyword=Underground dam en-keyword=Effective porosity kn-keyword=Effective porosity en-keyword=Storage capacity kn-keyword=Storage capacity en-keyword=Freshwater development kn-keyword=Freshwater development END start-ver=1.4 cd-journal=joma no-vol=9 cd-vols= no-issue=1 article-no= start-page=99 end-page=110 dt-received= dt-revised= dt-accepted= dt-pub-year=2004 dt-pub=20040227 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=DEM based Flood Extent Delineation in Dhaka City, Bangladesh en-subtitle= kn-subtitle= en-abstract= kn-abstract=Dhaka city, the capital of Bangladesh and home for more than 10 million people, has been affected by seasonal flooding almost in every year, however, the situation aggravates depending on rainfall and surrounding river waters. The aim of this paper is to delineate the flood extent in Dhaka city using digital elevation model (DEM), an integral part of geographic information system. Catastrophic floods of the 1988 and 1998 events are taken into consideration. Hydro-meteorological assessment of these events revealed that the 1988 flood was severe due to the lack of flood protection in the city together with transboundary flow of the major rivers while the 1998 flood was become deluge due to incessant monsoonal downpour along with early peaked of the river water levels. The 1998 event has done colossal damage in the city compare to the 1988 event. Flood extent estimation showed that DEM data is very precious to model inundation in the city, however, in order to be spatially explicit flood model, high resolution DEM is necessary. Finally, flood management issues are reviewed and found that combination of structural and nonstructural measures are necessary to help reducing flood induced losses and damage in the city. en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=DewanA.M. kn-aut-sei=Dewan kn-aut-mei=A.M. aut-affil-num=1 ORCID= en-aut-name=NishigakiMakoto en-aut-sei=Nishigaki en-aut-mei=Makoto kn-aut-name=西垣誠 kn-aut-sei=西垣 kn-aut-mei=誠 aut-affil-num=2 ORCID= en-aut-name=KomatsuMitsuru en-aut-sei=Komatsu en-aut-mei=Mitsuru kn-aut-name=小松満 kn-aut-sei=小松 kn-aut-mei=満 aut-affil-num=3 ORCID= affil-num=1 en-affil= kn-affil=岡山大学 affil-num=2 en-affil= kn-affil=岡山大学 affil-num=3 en-affil= kn-affil=岡山大学 en-keyword=Dhaka City kn-keyword=Dhaka City en-keyword=Floods kn-keyword=Floods en-keyword=Digital Elevation Model kn-keyword=Digital Elevation Model en-keyword=1998 and 1988 Floods kn-keyword=1998 and 1988 Floods END start-ver=1.4 cd-journal=joma no-vol=9 cd-vols= no-issue=1 article-no= start-page=87 end-page=98 dt-received= dt-revised= dt-accepted= dt-pub-year=2004 dt-pub=20040227 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Water Resources and Environmental Management in Ghana en-subtitle= kn-subtitle= en-abstract= kn-abstract=Three principal river basins are found in Ghana and the Volta River Basin is the major one, covering about three -quarters of Ghana. The basin is shared with Mali, Burkina Faso, Cote d'Ivoire, Togo and Benin. Water from the Volta River Basin is used for drinking water supply, generating hydro-electric power, irrigation, inland fisheries and lake transport. The sustainable management of the Volta River Basin is thus of great importance. Land use activities in the basin are thus closely monitored not only in Ghana, but also in the other riparian countries as well. This paper presents information and data on the water resources and environmental management of the Volta River Basin in Ghana. en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=Kankam-YeboahKwabena kn-aut-sei=Kankam-Yeboah kn-aut-mei=Kwabena aut-affil-num=1 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=Gyau-BoakyePhilip kn-aut-sei=Gyau-Boakye kn-aut-mei=Philip aut-affil-num=2 ORCID= en-aut-name=NishigakiMakoto en-aut-sei=Nishigaki en-aut-mei=Makoto kn-aut-name=西垣誠 kn-aut-sei=西垣 kn-aut-mei=誠 aut-affil-num=3 ORCID= en-aut-name=KomatsuMitsuru en-aut-sei=Komatsu en-aut-mei=Mitsuru kn-aut-name=小松満 kn-aut-sei=小松 kn-aut-mei=満 aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=岡山大学 affil-num=2 en-affil= kn-affil=岡山大学 affil-num=3 en-affil= kn-affil=岡山大学 affil-num=4 en-affil= kn-affil=岡山大学 en-keyword=water resources kn-keyword=water resources en-keyword=environmental management kn-keyword=environmental management en-keyword=Volta River Basin kn-keyword=Volta River Basin en-keyword=Ghana kn-keyword=Ghana en-keyword=water utilization kn-keyword=water utilization END start-ver=1.4 cd-journal=joma no-vol=25 cd-vols= no-issue= article-no= start-page=19 end-page=24 dt-received= dt-revised= dt-accepted= dt-pub-year=2003 dt-pub=200308 dt-online= en-article= kn-article= en-subject= kn-subject= en-title=The basic study on measuring method of contamination of the ground and the effective porosity by using dielectric constant measuring system kn-title=誘電率計測法による地盤の汚染度及び有効間隙率の測定方法に関する基礎的研究 en-subtitle= kn-subtitle= en-abstract= kn-abstract=For evaluating subsurface contamination, sampling method (boring) is commonly used, but this method cannot monitor the change of in-situ contamination and concentration with respect to time. The purpose of this study is to develop a measuring system for subsurface contamination in which a so-called FDR (Frequency Domain Refiectometry) and FDR-V (with Vector network analyzer) system was employed to measure the salinity and oil contaminant. This FDR and FDR-V method is a coaxial probe method, which allows the measurement of the dielectric. The experimental study indicates the possibility in measuring both the contaminant concentration and volumetric moisture content. In addition, the method for obtaining the effective porosity using this equipment was shown. Concretely, the sensor was inserted in the ground, and the liquid in which the dielectric constant differed on the water in the circumference was injected, and the method for obtaining the effective porosity from the change of the dielectric constant was proposed. en-copyright= kn-copyright= en-aut-name=NishigakiMakoto en-aut-sei=Nishigaki en-aut-mei=Makoto kn-aut-name=西垣誠 kn-aut-sei=西垣 kn-aut-mei=誠 aut-affil-num=1 ORCID= en-aut-name=KomatsuMitsuru en-aut-sei=Komatsu en-aut-mei=Mitsuru kn-aut-name=小松満 kn-aut-sei=小松 kn-aut-mei=満 aut-affil-num=2 ORCID= en-aut-name=KimMan-il en-aut-sei=Kim en-aut-mei=Man-il kn-aut-name=金萬鎰 kn-aut-sei=金 kn-aut-mei=萬鎰 aut-affil-num=3 ORCID= affil-num=1 en-affil= kn-affil=岡山大学環境理工学部 affil-num=2 en-affil= kn-affil=岡山大学大学院自然科学研究科 affil-num=3 en-affil= kn-affil=岡山大学大学院自然科学研究科 en-keyword=Dielectric constant kn-keyword=Dielectric constant en-keyword=Contamination kn-keyword=Contamination en-keyword=Frequency Domain Refiectometry kn-keyword=Frequency Domain Refiectometry en-keyword=In-situ kn-keyword=In-situ en-keyword=Effective porosity kn-keyword=Effective porosity END start-ver=1.4 cd-journal=joma no-vol=8 cd-vols= no-issue=1 article-no= start-page=53 end-page=62 dt-received= dt-revised= dt-accepted= dt-pub-year=2003 dt-pub=200303 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Floods in Bangladesh: A Comparative Hydrological Investigation on Two Catastrophic Events en-subtitle= kn-subtitle= en-abstract= kn-abstract=Flood becomes regular feature in riverrine Bangladesh. Every year, around 21 percent of land is flooded during monsoon season, however, in severe situation this figure shot up to more than 60 percent of total land. This paper is an attempt to analyze hydrological characteristics of two catastrophic events (1988 and 1998 flood) in the light of flood history in Bangladesh. The analysis demonstrates that the 1998 flood was more severe than the 1988 one. Moreover, the 1998 flood was also prolonged than the 1988 flood due to heavy rainfall inside and outside of the country. Finally, flood management issues in Bangladesh have been analyzed and found that structural solution to mitigate flood is not the only solution. Based on the analysis some possible mitigation options are put foward. en-copyright= kn-copyright= en-aut-name=A.M.Dewan en-aut-sei=A.M. en-aut-mei=Dewan kn-aut-name=A.M.Dewan kn-aut-sei=A.M. kn-aut-mei=Dewan aut-affil-num=1 ORCID= en-aut-name=NishigakiMakoto en-aut-sei=Nishigaki en-aut-mei=Makoto kn-aut-name=西垣誠 kn-aut-sei=西垣 kn-aut-mei=誠 aut-affil-num=2 ORCID= en-aut-name=KomatsuMitsuru en-aut-sei=Komatsu en-aut-mei=Mitsuru kn-aut-name=小松満 kn-aut-sei=小松 kn-aut-mei=満 aut-affil-num=3 ORCID= affil-num=1 en-affil= kn-affil=岡山大学 affil-num=2 en-affil= kn-affil=岡山大学 affil-num=3 en-affil= kn-affil=岡山大学 en-keyword=Flood kn-keyword=Flood en-keyword=Flood Management kn-keyword=Flood Management en-keyword=Danger level kn-keyword=Danger level en-keyword=Peak floods kn-keyword=Peak floods en-keyword=Deforestation kn-keyword=Deforestation END start-ver=1.4 cd-journal=joma no-vol=8 cd-vols= no-issue=1 article-no= start-page=39 end-page=52 dt-received= dt-revised= dt-accepted= dt-pub-year=2003 dt-pub=200303 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=The Hydrogeological Setting of Ghana and the Potential for Underground Dams en-subtitle= kn-subtitle= en-abstract= kn-abstract=Increasing human population, changing lifestyles and environmental considerations have resulted in increased utilization of groundwater resources worldwide. Thus, in turn, has led to the decline of groundwater levels in some countries and Ghana is no exception to this problem. To augment the availability of groundwater resources for various uses, numerous techniques have been developed in many part of the world, one of which is the construction of underground dams. The successful construction and utilization of underground dams, however, depends very much on the physical and hydrogeological conditions at the dam sites. Ghana is underlain by Precambrian crystalline igneous and metamorphic rocks ; and Paleozoic consolidated sedimentary formations. There are further subdivided and described locally as the Birimian, Dahomeyan, Buem, Togo Series, Tarkwaian, Granites, Voltain, Coastal Block Fault, Coastal Plain and Quaternary Alluvium. The review of these and the pre-requisite conditions necessary for the construction of underground dams indicate that underground dams could be constructed and utilized in some parts of Ghana, especially where the overburden is shallow, in the Dahomeyan granites and in the recent formations consisting of alluvial and coastal sands and gravels. This paper is part of a continuing research programme being carried out by the authors. en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=Kankam-YeboahKwabena kn-aut-sei=Kankam-Yeboah kn-aut-mei=Kwabena aut-affil-num=1 ORCID= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=Dapaah-SiakwanStephen kn-aut-sei=Dapaah-Siakwan kn-aut-mei=Stephen aut-affil-num=2 ORCID= en-aut-name=NishigakiMakoto en-aut-sei=Nishigaki en-aut-mei=Makoto kn-aut-name=西垣誠 kn-aut-sei=西垣 kn-aut-mei=誠 aut-affil-num=3 ORCID= en-aut-name=KomatsuMitsuru en-aut-sei=Komatsu en-aut-mei=Mitsuru kn-aut-name=小松満 kn-aut-sei=小松 kn-aut-mei=満 aut-affil-num=4 ORCID= affil-num=1 en-affil= kn-affil=岡山大学 affil-num=2 en-affil= kn-affil=Water Research Institute (CSIR) affil-num=3 en-affil= kn-affil=岡山大学 affil-num=4 en-affil= kn-affil=岡山大学 en-keyword=hydrogeology kn-keyword=hydrogeology en-keyword=geology kn-keyword=geology en-keyword=underground dam kn-keyword=underground dam en-keyword=sand-storage dam kn-keyword=sand-storage dam en-keyword=sub-surface dam kn-keyword=sub-surface dam en-keyword=water supply kn-keyword=water supply END start-ver=1.4 cd-journal=joma no-vol=6 cd-vols= no-issue=1 article-no= start-page=47 end-page=52 dt-received= dt-revised= dt-accepted= dt-pub-year=2001 dt-pub=20010228 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Study on Measuring System of Subsurface Contamination using Complex Dielectric Method en-subtitle= kn-subtitle= en-abstract= kn-abstract=For evaluating subsurface contamination, sampling method (boring) is commonly used, but this method cannot monitor the change of in-situ contamination and concentration with respect to time. The purpose of this study is to develop a measuring system for subsurface contamination in which a so-called FDR-V system (Frequency Domain Reflectometry with Vector network analyzer) was employed to measure the salinity contaminant. This FDR-V method is a coaxial probe method,which allows the measurement of the complex dielectric constant from 1GHz to 18GHz. The experimental study indicates the possibility in measuring both the salinity concentration and volumetric moisture content. en-copyright= kn-copyright= en-aut-name=KomatsuMitsuru en-aut-sei=Komatsu en-aut-mei=Mitsuru kn-aut-name=小松満 kn-aut-sei=小松 kn-aut-mei=満 aut-affil-num=1 ORCID= en-aut-name=NishigakiMakoto en-aut-sei=Nishigaki en-aut-mei=Makoto kn-aut-name=西垣誠 kn-aut-sei=西垣 kn-aut-mei=誠 aut-affil-num=2 ORCID= affil-num=1 en-affil= kn-affil=岡山大学 affil-num=2 en-affil= kn-affil=岡山大学 en-keyword=Dielectric constant kn-keyword=Dielectric constant en-keyword=Subsurface kn-keyword=Subsurface en-keyword=Salinity concentration kn-keyword=Salinity concentration en-keyword=Volumetric moisture content kn-keyword=Volumetric moisture content END start-ver=1.4 cd-journal=joma no-vol= cd-vols= no-issue= article-no= start-page= end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2000 dt-pub=20000325 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=誘電法による地盤の浸透特性の計測手法に関する研究 en-subtitle= kn-subtitle= en-abstract= kn-abstract= en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=小松満 kn-aut-sei=小松 kn-aut-mei=満 aut-affil-num=1 ORCID= affil-num=1 en-affil= kn-affil=岡山大学 END start-ver=1.4 cd-journal=joma no-vol=5 cd-vols= no-issue=1 article-no= start-page=107 end-page=112 dt-received= dt-revised= dt-accepted= dt-pub-year=2000 dt-pub=20000229 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Laboratory Experiment on Failure of Embankment en-subtitle= kn-subtitle= en-abstract= kn-abstract=Failures of railway embankments in Japan usually occur during rainfall period due to the rise of water level in the embankments. Laboratory experiments were carried out to elucidate the initiation of failure of embankment under the rise of water level. The changes in pore-water pressure were monitored during the rise of water table and at the initiation of failures. The experiment results showed that main failure of embankment was initiated by development of localized unstable area at the toe of the embankment models during the rise of water level. This indicates that failure of embankments was a consequence of instability of the toe of the slope induced by saturation process under drained condition. en-copyright= kn-copyright= en-aut-name= en-aut-sei= en-aut-mei= kn-aut-name=TohariAdrin kn-aut-sei=Tohari kn-aut-mei=Adrin aut-affil-num=1 ORCID= en-aut-name=NishigakiMakoto en-aut-sei=Nishigaki en-aut-mei=Makoto kn-aut-name=西垣誠 kn-aut-sei=西垣 kn-aut-mei=誠 aut-affil-num=2 ORCID= en-aut-name=KomatsuMitsuru en-aut-sei=Komatsu en-aut-mei=Mitsuru kn-aut-name=小松満 kn-aut-sei=小松 kn-aut-mei=満 aut-affil-num=3 ORCID= affil-num=1 en-affil= kn-affil=岡山大学 affil-num=2 en-affil= kn-affil=岡山大学 affil-num=3 en-affil= kn-affil=岡山大学 en-keyword=embankment kn-keyword=embankment en-keyword=failure process kn-keyword=failure process en-keyword=seepage face kn-keyword=seepage face en-keyword=toe failure kn-keyword=toe failure en-keyword=overall instability kn-keyword=overall instability END