Ishikari Plain Research Articles

Characteristics of the Avifauna in a Rice Field Dominated Rural Area, and Habitat Use by Grassland Birds in Western Hokkaido, Japan

Rural areas provide various habitats for birds, and some studies have revealed habitat associations in rural bird communities in Japan. Previous studies have primarily focused on waterbirds or the habitat values of abandoned farmland, thus little is known about the importance of cultivated land for rural bird communities. Therefore, in this study, I clarified the characteristics of the avifauna in a rural area of the Ishikari Plain in Shinshinotsu Village, Western Hokkaido, and examined habitat utilization of cultivated land by eight major grassland species; Bull-headed Shrike Lanius bucephalus, Eurasian Skylark Alauda arvensis, Black-browed Reed Warbler Acrocephalus bistrigiceps, Siberian Rubythroat Calliope calliope, Stejneger's Stonechat Saxicola stejnegeri, Chestnut-eared Bunting Emberiza fucata, Black-faced Bunting E. spodocephala, and Common Reed Bunting E. schoeniclus. I conducted bird surveys along three 2-km line-transect routes among rice fields with some wheat, non-wheat crop fields, and weedy areas from April to October from 2016 to 2018. I recorded a total of 51 species of three general types: grassland birds, residential birds, and water birds. Rice fields in this study areas were flooded during early to mid-May to mid to late August, however species-specific habitat utilization analyses revealed that a small number of Eurasian Skylark, Stejneger's Stonechat, and Chestnut-eared Bunting inhabited the rice fields during study periods other than the flooding season. A relatively large number of Eurasian Skylark was observed in wheat fields and non-wheat crop fields throughout the study period, and Stejneger's Stonechat and Chestnut-eared Bunting were temporarily observed in those habitats. The other five species only rarely observed in rice, wheat, or non-wheat crop fields, but all eight species were observed in weedy areas. The characteristics of the avifauna in this rural area of Western Hokkaido proved to be quite different from previous studies conducted in the Kanto Region of Honshu. For the conservation of biodiversity and birds in rural areas, it is necessary to investigate the avifaunal characteristics of various regions of Japan.

Investigation of stratigraphy of boring core drilled in the Nakanuma-cho of Sapporo,and buried landforms in the Ishikari Plain, Japan

Investigation of stratigraphy of boring core drilled in the Nakanuma-cho of Sapporo,and buried landforms in the Ishikari Plain, Japan

Influences of Orography and Coastal Geometry on a Transverse-Mode Sea-Effect Snowstorm over Hokkaido Island, Japan

Abstract Sea-effect snowstorms generated over the Sea of Japan produce consistent and often heavy snowfall throughout the winter season, impacting downstream communities in northern and central Japan. Here, we use observations and Weather Research and Forecasting (WRF) Model simulations to examine the precipitation distribution produced by transverse-mode sea-effect snowbands that interacted with the mountainous terrain circumscribing Ishikari Bay, Hokkaido Island, Japan, on 12 January 2014. The bands observed here were horizontal convective rolls aligned normal to the mean flow and were ~10 km wide and up to ~100 km long. The bands approached Ishikari Bay at intervals of ~10–16 min, intensifying as they progressed through a quasi-stationary, elongated enhancement region that paralleled the Shakotan Peninsula and extended into the Ishikari plain. Hydrometeor advection, through an ascent region over the northeast slope of the Shakotan Peninsula, and along clockwise-turning trajectories steered by the boundary layer directional shear, contributed to sustained precipitation enhancement along a curve in the elongated enhancement region near the entrance to Ishikari Bay. Downstream, orographic flow deflection by the coastal mountains, likely accentuated by thermal and roughness gradients along the Shakotan Peninsula’s shoreline, produced convergence and ascent along the elongated enhancement region. This study demonstrates the impact of downstream topography on sea-effect snowstorms and has implications for improving the prediction of snowfall in this and other lake- and sea-effect regions.

Factors affecting arsenic content of unconsolidated sediments and its mobilization in the Ishikari Plain, Hokkaido, Japan

Arsenic (As) contamination of groundwater is often caused by As leaching from geological formations. This study focused on factors affecting As content in unconsolidated sediments by using three sediment cores in the Ishikari plain, Hokkaido, Japan. The geochemical properties of the sediments were characterized by the chemical and mineral compositions as well as leaching experiments and sequential extractions of As. The results showed that higher As content of 4–9 mg/kg was observed in peat layers with organic matter content > 10 wt%, and that higher As contents deeper than 8 m below the surface were also observed. The deeper sediments were likely to be formed in brackish water conditions due to lower weight ratios of organic carbon content to sulfur content (C/S < 10). The results of the leaching experiments showed that As was mobilized at slightly alkaline region. These indicate that the distribution of As depended on the organic content in the sediments and sedimentation condition, and that the mobility of As in the sediment was affected by pH.

石狩平野における水稲品種の栽培特性 : 近年の生育相と収量性(年次講演会要旨)

石狩平野における水稲品種の栽培特性 : 近年の生育相と収量性(年次講演会要旨)

Basement of Chuseki-so and sedimentary surface of the MIS 5e deposit in the Ishikari Plain, Hokkaido, Japan

Basement of Chuseki-so and sedimentary surface of the MIS 5e deposit in the Ishikari Plain, Hokkaido, Japan

Distribution estimation of sandstone reservoir at Northern Ishikari plain, Hokkaido, Japan.

Distribution estimation of sandstone reservoir at Northern Ishikari plain, Hokkaido, Japan.

Latest Pleistocene to Holocene deposits of the inner part of the Ishikari Plain

Latest Pleistocene to Holocene deposits of the inner part of the Ishikari Plain

北海道石狩平野の縄文海進の痕跡と汽水湖（古石狩湖）の広がり

北海道石狩平野の縄文海進の痕跡と汽水湖（古石狩湖）の広がり

NEST-SITE SELECTION OF NORTHERN GOSHAWKS AND EURASIAN SPARROWHAWKS IN A FRAGMENTED LANDSCAPE IN NORTHERN JAPAN

ABSTRACT We measured the characteristics of trees and sites of 14 Northern Goshawk (Accipiter gentilis) and 14 Eurasian Sparrowhawk (Accipiter nisus) nests in the Ishikari Plain of Hokkaido, Japan, where their nesting habitats were fragmented into small woodlots. We also randomly located 25 plots (0.033 ha each) in unused woodlots to compare differences between nest and random sites. Goshawks nested in a variety of trees and diameters at breast height (dbh) of nest trees were significantly larger than the mean values for all trees in the nest sites, and were similar to the largest trees in these sites. The heights of nest trees were significantly larger than the mean values of all trees in the nest sites. Goshawks nested in a variety of forest types, in proportion to their availability. The dbh and tree heights of sparrowhawk nest trees were significantly larger than the mean values of all trees in the nest sites, and were significantly smaller than the largest trees in these sites. Sparrowhawks nested on...

石狩平野北西部における2003年十勝沖地震時の長周期地震動

石狩平野北西部における2003年十勝沖地震時の長周期地震動

2003年十勝沖地震による周期数秒から十数秒の長周期地震動と石油タンクの被害

The 2003 Tokachi-oki, Japan, earthquake generated sloshing of liquid in large oil storage tanks with capacities over 1, 000m3 in Hokkaido and caused damage to many of them. The maximum sloshing wave heights of about 3m were observed at two tanks with natural periods of the fundamental mode of sloshing (Ts) of 7s and 5.9s in the Tomakomai western port area and at a tank (Ts=5s) in the city of Ishikari. Damage occurred in 190 large tanks in the southern part of Hokkaido. In and around the city of Tomakomai, 170 large tanks have been damaged and this corresponds to a high damage ratio of 58%. Serious damage occurred in nine tanks and eight of them concentrated in the Tomakomai western port area, where fire broke out from two tanks and floating roofs sank into the oil in seven tanks. One of the two fires was the ring fire that lasted for about 7 hours, while the other extended to the open top fire and it lasted for about 44 hours. It was long-period strong ground motion with periods from several seconds to around 10s that generated sloshing in the large tanks. In the Yufutsu plain embracing the Tomakomai area and the Ishikari plain, the shaking with a period of 7s was stronger than that in the plains in the eastern part of Hokkaido even though the latter were closer to the source region. In the plains of Yufutsu and Ishikari, the long-period strong ground motion was not confined to the Tomakomai area but distributed widely over the plains with the strongest motion observed in the area along the north-to-south axis connecting the center of the Yufutsu plain with the eastern part of the Ishikari plain. This long-period strong ground motion is presumed to be excited by the sediments reaching a thickness of 2 to 3km inside the plains. Around the Tomakomai western port, the long-lasting long-period shaking was observed with velocity responses with a damping factor of 1% keeping over 1.5m/s in a period range between 3.7 and 8.3s and with the peak value of 2.8m/s at a period of 4.8s. This peak value is about 2.5 times as large as the ground motion level that corresponds to a code established for large oil storage tanks by the Japanese fire laws. In the Tomakomai western port area, no recordings for the last three decades are larger than the ground motion level at periods of several seconds observed during the 2003 Tokachi-oki earthquake. Comparisons between the observed maximum sloshing wave heights and the observed ground motions indicate that the maximum sloshing wave heights scale with the velocity responses at Ts's. From the sloshing response analyses for the tanks in the Tomakomai area based on the observed ground motions, we found that the sloshing with the maximum wave heights of 3m and 1.3m occurred in the seriously damaged tanks with capacities of 30, 000 to 40, 000m3 (Ts-7 to 8s) and about 110, 000m3 (Ts-12s), respectively.

衛星データによるメッシュ単位の気候値（旬別平年値）推定に関する基礎的研究

Basic studies on the estimation of normals for decade air temperature at unit cell were performed using daily mean air temperature derived from satellite IR data. Analyses were taken with the assumption that “the difference between a daily mean air temperature and normals for decade air temperature is approximate among areas sharing similar climates”. Items and procedures for analyses are as follows.(1)Characteristic for mean decade air temperature and frequency for decade air temperature. (2)Classification for AMeDAS observation sites in Hokkaido to make some groups of areas sharing similar climates. (3) Characteristic of difference between a daily mean air temperature and normals for decade air temperature, and proof of the assumption. (4) Estimation of daily mean air temperature derived from satellite IR data. (5) Estimation of quasi-normals for decade air temperature using satellite IR data. The results for analyses are as follows. (1) The assumption that the difference between a daily mean air temperature and normals for decade air temperature is approximate among areas sharing similar climates was proved. Therefore, it is possible to estimate quasi-normals for decade air temperature using daily mean air temperature derived from satellite IR data. (2) There was a significance level of 1% between daily mean air temperature of AMeDAS data and surface temperature for 960m cell derived from Landsat TM data on July 8, 1993 in Ishikari Plain. And quasi-normals for decade air temperature in early July could be estimated to 0.1°C accuracy, except for data from Eniwa-Shimamatsu AMeDAS observation site.

An analysis of the forest edge environment preferred by goshawks in Ishikari Plain, Japan

An analysis of the forest edge environment preferred by goshawks in Ishikari Plain, Japan

静的，および動的データを用いたフラクチャーモデリング

Yufutsu field is located in the southern Ishikari Plain, central Hokkaido, in northern Japan. Japex commenced the production in 1996 and is producing gas and condensate. The reservoir is a naturally fractured granite and conglomerate. The permeability and porosity is very low. The reservoir is so heterogeneous that it cannot be modeled with the conventional method. We modeled it with the discrete fracture network (DFN) model by using the statistical properties of the fractures extracted from static data such as borehole images.The borehole images show that the fractures can be divided into two families according to the nature. One includes fractures of wide apertures. This family keeps a clear tendency of the azimuth and dip. The other includes narrow aperture fractures whose azimuth and dip are more scattered. Two sets of DFN model were made and merged to one model to make an overall DFN model.The model was calibrated successfully with the dynamic data such as pressure buildup data and production history. The pressure buildup data were used for the calibration of fracture properties and the production history were used for the calibration of spatial distribution of fractures.

Radar Echo Characteristics of the Localized Heavy Snowfalls around Sapporo, Japan.

The radar echo analysis in which the heavy snowfall intensity stronger than 6cmh-1 in snow depth was recorded on the lower elevation angle of radar scanner was carried out from the viewpoint of traffic transport facilities and localized heavy snowfall phenomena on the Ishikari Plain including Sapporo, Hokkaido, Japan. From the analysis of radar echo, it was clarified that there were high frequency areas. Furthermore, it was understood that there were some areas with sudden changes in snowfall intensity stronger than 10 cmh-1 in a limited few km2 in a horizontal scale and 10 minute duration in calm weather condition. Vertical cross section analyses across the abnormal heavy snowfall areas in which there were recorded with an intensity stronger than 6 cmh-1 by radar showed that the drastic increase of snowfall intensity occurred between 200m and 400m above the ground surface. The change of the maximum value of the radar echo intensity at around 200m level was estimated by the growth of large snowflakes which were aggregated and formed quickly under the horizontal and vertical wind shears at the same level.

中央北海道南部における新生代テクトニクスの変遷と油田構造形成

The Yufutsu oil and gas field, Tomakomai City, southern Ishikari Plain, centralHokkaido, has its naturally fractured reservoir in Cretaceous granitoids and overlying Eoceneconglomerates, which form a large horst-complex delineated by normal faults. Stratigraphic andstructural features of the Yufutsu field and its surrounding areas indicate that prominentextensional deformation shaped the horst during the late Oligocene to early Miocene, when the lateCenozoic sedimentary basin in the southern Ishikari Plain originated and subsequently developedstepwise from an extensional-transtensional (?), relatively localized basin to a transpressionalforeland basin of a regional scale. Understanding of these Cenozoic tectonic processes leads to anexploration concept which counts basement horsts for traps with fractured reservoir and deeplyburied coal-bearing strata for hydrocarbon sources. The MITI Umaoi well, drilled 25km north ofthe Yufutsu field, proved this concept practical even in a subthrust setting, as it hit a wellpermeable fractured reservoir within a basement horst. A new lithostratigraphic unit, Minami-naganuma Formation (Upper Oligocene), is formally proposed.

人工衛星データを使用した地域蒸発散量の推定

A new method for estimation of regional evapotranspiration using satellite derived data is proposed. This method estimates daily regional evapotranspiration by combining high resolution LANDSAT-TM data, NOAA-AVHRR data of which the estimation accuracy of surface temperature is high, and wide-area representative radiosonde data.As a case study, we caluculated the epavotranspiration for 2 districts in the Hokkaido Ishikari Plain using this method. Results are reasonable.Though there is no direct method for verification, comparison with the Prisetley-Taylor method shows that the results correctly reflect the effects of land use. This result shows that this method is sensitive to land use and that it is a useful method for estimation of the regional evapotranspiration. The representativeness of the radiosonde data is questionable in the comparison between results from 2 regions.Though there are some details to be improved, this could be a valuable method by which the regional evapotranspiration can be estimated using easily obtainable data.

１９９５／１９９６年の札幌付近の大雪

Record-beaking heavy snowfalls were observed at Sapporo area in the Ishikari Plain, Hokkaido from December 1995 to January 1996. The total snowfall in December 1995 at Sapporo was 256cm which was more than twice of the monthly average.

1988年9月22日千歳竜巻のライフサイクル

In the afternoon of September 22, 1988, a supercell storm developed over the Ishikari Plain, in Hokkaido, Japan. A single-funnel F1 tornado was spawned in Chitose City, near Sapporo. The characteristics of the structure and the life cycle of the Chitose tornado were revealed by radar observations, ground survey, photographs, videotape, and meteorological data analyses. The Chitose tornado had a lifetime of 20 minutes and funnel width of 150 m at cloud base. The life cycle of the tornado was divided into four stages according to the detailed structure of the funnel and damage characteristics : the formation stage was characterized by a descending funnel, the mature stage characterized by touchdown of a visible funnel and a formation of strong dust cloud, the shrinking stage characterized by tilting and meandering funnel, and decaying stage that lead to the dissipation of the funnel. The mesocyclone of 7 km in diameter developed at 2.5 km AGL in the parent cloud and was accompanied by a misocyclone of 1 km in diameter. The angular momentum of the tornado circulation at the height of 400 m AGL was nearly equal to that of the misocyclone at 2.5 km AGL. The time and space relationship between surface damage, the tornado funnel and the mesocyclone was revealed. The width of the surface damage area was nearly equal to the width of the dust cloud (200 m) and was 10 times larger than the surface funnel width. Although the surface funnel initially formed right below the misocyclone, the funnel top near the cloud base and the funnel bottom near the surface moved in quite different ways, since the parent cloud moved at a speed of 5 ms -1 and the surface funnel at a speed of 1.2 ms -1 .