Recent Alluvial Plains Research Articles

Pedological Development of Soils in Eastern Agroclimatic Zone of Haryana through Field Morphology Rating System

A study was carried out to evaluate the pedological development of soils in Eastern agroclimatic zone of Haryana using field morphology rating system. For this, nine pedons were excavated to study the morphological properties in field and rating scale was used to compare adjacent horizons with each other to give a comparison of the relative distinctness of horizons or to compare horizons in the solum with the C-horizon to give a relative profile development in soils occurring in different physiographic positions i.e. Shiwalik hills, recent and old alluvial plains with different precipitations throughout the study area. Some chemical properties were also used to evaluate the pedogenic factors as a result of being affected by process and factors of soil formation due to the distinct effect of climate. The Relative Horizons Distinctness (RHD) ratings were made by a comparison of adjacent horizons. The soils of Shiwalik hills, recent and old alluvial plains have RHD ratings from 6 to 14, 3 to 11 & 3 to 12, respectively. The RPD ratings were made by a comparison of the C horizon to the horizons above it in the profile. The soils of Shiwalik hills, recent and old alluvial plains have RPD ratings from 7 to 15, 3 to 14 & 5 to 16. The RPD values of all the profiles were maximum in A horizon due to maximum pedological development influenced by weathering. So, studies of these soils indicated the pedological development in the order of Shiwalik hills > old alluvial plains > recent alluvial plains.

Mapping of the Buried Paleochannels on the Terminal Fans in the Western Ganga Plain: A Geomorphological and Ground Penetrating Radar-based Approach

Abstract Paleochannels are valuable tools for delineating tectonics, climate, anthropogenic activities, reconstructing the paleo-geography, and studying the geomorphological evolution of the alluvial plains. Paleochannels on the terminal fans provide crucial information regarding their geomorphic evolution in space and time. Furthermore, paleochannels could be a good source for groundwater exploration. Exposed paleochannels in the recent alluvial plains are mappable by remote sensing and field evidence. However, mapping becomes difficult due to burial in relatively older alluvial surfaces, and anthropogenic disturbances complicate the case. This paper deals with an integrated method of mapping the buried paleochannels in the terminal fans from the western Ganga plain. Paleochannels have been mapped on three Holocene terminal fans, using remote sensing and Google Earth images, and Cartosat DEM. As continuity of the entire length of paleochannels could not be traced by the above tools due to burial and intense anthropogenic modifications, aligned surface water bodies were helpful at places to ascertain their continuity. The ground penetrating radar (GPR) survey by bistatic antennae (100 MHz frequency in distance mode) detected the subsurface existence of these buried paleochannels up to a maximum depth of about 35 m. Field evidence of some of these buried channels was confirmed at few excavations by the presence of channel sand. A previous study of these terminal fans through optical stimulated luminescence (OSL) dating suggests that channel abandonment occurred between 4.7 to 2.3 Ka, coinciding with the period of the dry climate and intense surface faulting episodes in the Ganga plain.

Mineralogy of Alluvial Soils Developed in Narmada River Basin in West Coast of Gujarat

Clay minerals have played a significant role for the plant nutrient management for crop production. Soils of recent and old alluvial plains deposited by Narmada river in Jhagadia block were investigated for their mineralogical makeup. The soils on recent alluvial plains (P1) (Fluventic Haplustepts) are very deep, moderately well drained, very dark grayish brown to very dark brown, silt loam to silt clay loam on level to nearly level slope with clay loam surface and slight erosion. The soils of old alluvial plain (P2) (Vertic Haplustepts) are similar to recent alluvial plain with clayey texture and moderate erosion. The pedons were sampled at one km (recent alluvial plain) and at two km (old alluvial plain) distance from Narmada river stream. The soils of recent alluvial plain are slightly alkaline (pH 7.5-8.5), slightly calcareous (<5% CaCO3) with moderate cation exchange capacity (CEC) and high in base saturation (>90%). The soils of old alluvial plain have high CEC and CaCO3 in sub-surface horizons. This paper presents a detailed study on clay minerals in surface and sub-surface sediments deposited by the Narmada river drainage basin. Clay content was ranged from 30-50% in recent alluvia and 50-60% in old alluvia. The soils of recent alluvia were high in silt fraction (40-47%) which plays an active role in potassium nutrition. The smectite content was significantly higher (weighted mean 64.9%) in old alluvial plain compared with recent plain (weighted mean 37.8%). A reverse pattern of mica distribution was observed in clay fraction of both the plains. The distribution of quartz and K/Na feldspars showed similar trends in sand fraction but wide variability was observed in the case of hydralsite, kenyaite, and boehmite content with depth. The mineralogical study indicated that the clay mineral assemblage of both sites varied in smectites and mica, which imparts heterogeneity to soil properties.

REVIEW OF THE LAND SUBSIDENCE HAZARD IN PEKALONGAN DELTA, CENTRAL JAVA: INSIGHTS FROM THE SUBSURFACE

Land subsidence is a global threat to coastal areas worldwide, including the North Java coastal area. Of many areas experiencing land subsidence in North Java, the rate of land subsidence in Pekalongan has matched the high subsidence rates usually found in big cities. The rate of land subsidence in Pekalongan far exceeds the sea-level rise, resulting in a looming threat of land loss. The devastating impacts of land subsidence are the manifestation of its subsurface movement. Therefore, it is essential to understand the subsurface to elucidate the mechanism of land subsidence. Previous studies on land subsidence in Pekalongan are mainly related to subsidence rate monitoring and have not elaborated on the subsurface condition. This paper reviews the Pekalongan subsurface geology based on available literature to provide insight into the land subsidence problem. The results revealed that the land subsidence occurs in the recent alluvial plain of Pekalongan, consisting of a 30-70 m thick compressible deposit. Possible mechanisms of land subsidence arise from natural compaction, over-exploitation of confined groundwater, and increased built areas. As the seismicity of the study area is low, tectonic influence on land subsidence is considered negligible. It is expected that the offshore, nearshore, and swamp deposits are still naturally compacting. As the surface water supply is minimal, over-exploitation of groundwater resources from the deltaic and Damar Formation aquifers occurs. In the end, future research direction is proposed to reduce the impacts of the subsidence hazard.

Assessing effect of dynamic compaction on liquefaction potential using statistical methods – a case study

ABSTRACTThis article is aimed at illustrating the practical use of statistical methods in geotechnical engineering. As an example, the efficacy of dynamic compaction (DC) in the mitigation of liquefaction hazard is studied through a case study of a site in the Chang-Hwa Coastal Industrial Park in Changhua County, Taiwan. Before DC, the soil at the study site, which mainly consists of a layer of hydraulic fill of silty sand to fine sand underlain by recent alluvial plains (Qa), is deemed susceptible to liquefaction. After DC, the soil at the study site is improved such that the liquefaction potential is greatly reduced. The efficacy of DC in reducing liquefaction potential is evaluated quantitatively using the statistical methods, and the effectiveness of these statistical methods, especially when used with visualisation technique, is demonstrated. This provides a basis towards risk-based communication and decision making in the setting of practical applications.

Effect of resource conservation technologies on soil structural conditions in temporary waterlogged alluvial plains of the river Yamuna

A study was conducted in farmers’ fields of Rai block of Sonepat district, Haryana, India to study the long term impact of two widely adopted resource conservation technologies (RCT's) namely bed planting and zero tillage on structural properties of soils of recent alluvial plains of the river Yamuna. Aggregate mean weight diameter by dry sieving and wet sieving (DS-MWD and WS-MWD) under different RCT's were studied to compare structural condition of the soils under continuous use of these technologies. Other important structural indices such as dispersion ratio (a measure of ease of dispersion; DR), colloid moisture equivalent ratio (a measure of ease of percolation; CMER), erosion ratio (ER), stability index (SI), soil organic carbon (SOC), clay ratio (CR) were also studied to monitor the susceptibility of soil to erosion in the study area. Results revealed that in the surveyed villages under conventional tillage (CT), the mean (of 6 samples) magnitude of DR and ER were 0.58 and 0.82, respectively, and CMER was &lt;1, which indicated the erodible nature of these soils. Analysis of data of bed and conventional systems revealed that on an average, there was about 19.08 % increase in SOC in bed planted system compared to conventional system. The decrease of DR, ER and CR from 0.66, 0.52 and 4.25 under CT to 0.42, 0.28 and 2.38 under beds indicated reduced eroding tendency of these soils under bed planting. Comparison of soil data of ZT and CT showed improvement (33.19 %) in SOC, and reduction in BD and PR under ZT plots compared to CT. The decrease of DR, ER and CR from 0.74, 0.63 and 5.99 under CT to 0.6, 0.46 and 3.8 under ZT indicated improved aggregation under ZT. Similarly increase in CMER and SI from 0.66 and 9.21 under CT to 0.7 and 20.4 under ZT also indicated improved soil structural condition by adoption of zero tillage. Thus, it was concluded that by adopting suitable RCT’s, soil carbon and aggregation were improved and soils became more resistant to erosion.

Is Australia a tectonically stable continent? Analysis of a myth and suggested morphological evidence of tectonism

Occasional references to the relative tectonic instability of the Australian continent have been published over the last hundred years or so. Youthful tectonic forms were described from various parts of the continent throughout that period. Despite this, it was repeatedly claimed that the shield lands in particular were tectonically stable, and as recently as this century reference has been made to a concept embracing a tectonically inert continent. However, some 60 years ago, the accumulated evidence convinced E.S. Hills that in Australia all land surfaces, including the shield lands, and even recent alluvial plains, were tectonically disturbed. This conclusion was reinforced by analyses of seismicity and faulting; by regional geological mapping that revealed widely distributed tectonic forms and especially fault-related features, many of them of neotectonic age; by technological advances that allow faulting episodes to be closely dated; by the recognition of underprinting; and by the realization that many minor forms, previously unrecognized or attributed to other mechanisms or processes, are associated with crustal stress and are of tectonic origin. Thus, while Australia is a relatively stable continent, it is subject to widespread small-magnitude earth movements. Ironically, in view of earlier thinking, neotectonic forms may be better developed and preserved on the shields than elsewhere.

Physiographic soil map delineation for the Nile alluvium and desert outskirts in middle Egypt using remote sensing data of EgyptSat-1

The objectives of this study are to produce a physiographic soil map with correlated attributes to be a base for extra modifiers within the land information system. This integrated data will serve the purposes of land use planning, precision farming practices and to be applied in other areas using the extrapolation approach. The Satellite data of EgyptSat-1 were projected on an area of Middle Egypt that represents unique physiographic features over portions of Beni Suef, El Fayoum, Helwan, and October Provinces. The spectral signatures of the land patterns were delineated by the visual interpretation using the physiographic approach, while soil taxa were categorized according to the key of Soil Taxonomy ( USDA, 2010), resulting in two landscape categories. The first category includes older and developed parent materials, covering the following units: (a) Pediplains of residual soils over limestone parent rock, having soils of Lithic Haplocalcids, loamy skeletal. (b) Terraced old alluvial plains represent the formerly deposited alluvium that preceded the recent one of the River Nile alluvium. They includes soils of Typic Calcigypsids, loamy skeletal and old alluvial plain but are currently managed under cultivation. The soils are dominated by Typic Haplocalcids, loamy skeletal. (c) Wadis that were shaped by the paleodrainage erosion, are currently subjected to the seasonal flush flooding and are sparsely vegetated including soils of Typic Torrifluvents, lamy skeletal (calcareous); Typic Torriorthents, sandy skeletal, and Typic Torriorthents, sandy. (d) Aeolian plain “partly cultivated” includes soils of Typic Torripsamments (calcareous). The second category is a recent River Nile alluvium that formed the following units: (a) Terraced recent alluvial plain “cultivated” includes soils of Entic Calcitorrerts, fine and Typic Haplotorrerts fine. (b) Recent flat alluvial plain includes soils of Typic Haplotorrerts, fine. (c) Meandering belt is aligning the River Nile course with courser sediments comparing to the recent alluvial plains. This belt is sub divided as levees that have soils of Typic Torriorthents, fine lomy; point bars with soils of Typic Torriorthents, coarse lomy; river banks with soils of Typic Torriorthents, coarse lomy; bow bars with Typic Torriorthents, sandy and Typic Torriorthents, coarse loamy and meander scars with soils of Typic Torriorthents, sandy. All these taxonomic classes are hyperthermic, being developed under the hyperthermic temperature regime within an aridic moisture regime.

The effects of land uses on soil erosion in Spain: A review

Abstract Soil erosion is a key factor in Mediterranean environments, and is not only closely related to geoecological factors (lithology, topography, and climatology) but also to land-use and plant cover changes. The long history of human activity in Spain explains the development of erosion landscapes and sedimentary structures (recent alluvial plains, alluvial fans, deltas and flat valleys infilled of sediment). For example, the expansion of cereal agriculture and transhumant livestock between the 16th and 19th centuries resulted in episodes of extensive soil erosion. During the 20th century farmland abandonment prevailed in mountain areas, resulting in a reduction of soil erosion due to vegetation recolonization whereas sheet-wash erosion, piping and gullying affected abandoned fields in semi-arid environments. The EU Agrarian Policy and the strengthening of national and international markets encouraged the expansion of almond and olive orchards into marginal lands, including steep, stony hill slopes. Vineyards also expanded to steep slopes, sometimes on new unstable bench terraces, thus leading to increased soil erosion particularly during intense rainstorms. The expansion of irrigated areas, partially on salty and poorly structured soils, resulted in piping development and salinization of effluents and the fluvial network. The trend towards larger fields and farms in both dry farming and irrigated systems has resulted in a relaxation of soil conservation practices.

日本列島における沖積層の層厚分布特性―沖積平野における災害脆弱性評価のための地形発達モデルの構築にむけて―

In warm-humid and tectonically active regions such as Japan it is important to investigate the geomorphic development of recent alluvial plains controlled by sea-level changes to prevent natural disasters. This is because human activities concentrate coastal alluvial plains composed of unconsolidated soft sediments (alluvium) including inner-bay mud, which amplify seismic intensity. However, we know little about the general shape of the alluvium quantitatively although several river basins have been investigated in detail. We selected 33 trunk rivers throughout Japan and measured the Present River long-Profile (PRP) along with the Last Glacial River long-Profile (LGRP) defined by the depositional surface of basal gravel layers formed under the influence of falling sealevels during the last glacial period. The thickness of the alluvium given by the relative altitude between PRP and LGRP was basically in proportion to the size of the river basin, and it decreased linearly upstream with the exception of several rivers such as Shinano, Kiso, Oita, and Yoshino. Along these rivers, the alluvium is markedly thicker than expected probably because of tectonic subsidence occurring repetitively after formation of basal gravel layers. This implies that the fluvial response to sea-level change is sensitive enough to distinguish the effects of the accumulation of tectonic movements after deposition of basal gravels. In stable or slightly uplifted areas, the inland distribution of inner-bay mud is basically controlled by river basin size.

Detection of neotectonic deformations along the Rio do Peixe Valley, Western São Paulo State, Brazil, based on the distribution of late Quaternary allounits

Terrace deposits (34 10 ka) were mapped in the Rio do Peixe valley and submitted to an allostratigraphic analysis. Three allomembers (viz. “A”, “B”, and “C” ) were established in the medium to lower river valley and other three allounits (allomembers “ L”, “M” and “N”) were defined in the upper valley. It is probable tha “B” and “M” allomembers represent the same stratigraphic level. The spatial distribution of these allomember shows the influence of the Recent base-level changes, due to neotectonics events. Longitudinal cross-section o the Rio do Peixe valley shows that it is possible to define some areas with differential tectonic movements, tha includes uplift blocks (prone to erosion and terrace deposit destruction), and other areas with relative subsidence, controlling both the Recent alluvial plains and the preservation of some ancient terrace deposits. This scenery is in accordance with regional tectonic studies.

Landscape Change and Ecosystem Classification in a Municipal District of a Small City (Isernia, Central Italy)

Landscape changes taking place from 1954 to 1992 in the muncipal district of Isernia city (Central Italy) were described in relation to a system of ecosystem classification. Isernia municipal district was selected for study because recent historic changes in this area represent a typical example of landscape transformation similar to many small cities of Italy and other Mediterranean countries. To assess overall changes, three land cover maps (scale 1:25,000) were derived from panchromatic aerial photographs and field surveys. These were then digitalised in a Geographic Information System. A Land Facet (LF) map was derived by combining a phytoclimatic, a lithostatigrafic and a topographic map, and then digitalised as data layers in the same GIS. Results demonstrated two main landscape transformation trends: forest and semi-natural areas increased (8%), whereas agricultural areas decreased (12%). The urban area was relatively small during the entire analysed period, growing from 1% in 1954, to just 5% in 1992. Forest coverage was significant on reliefs, on hillside ecosystems such as limestone and on clay and marl hills LF. Arable land was particularly significant in flat ecosystems with deeper soils, such as on recent alluvial plain LF. These temporal changes were interpreted as being related to the replacement of traditional farming methods (grazing pastures) with more intensive methods (crop fields), especially on alluvial plains.

Attenuation Relationships of Peak Ground Acceleration and Velocity for Crustal Earthquakes in Taiwan

Strong seismic ground-motion data obtained by the Taiwan Strong Motion Instrumentation Program (tsmip) and Central Mountain Strong Motion Array (cmsma) are used to derive new attenuation relationships for the vertical and horizontal peak ground acceleration (pga) and peak ground velocity (pgv) for crustal earthquakes in Taiwan. More than 7900 three-component accelerograms recorded from 51 crustal earthquakes in Taiwan, with M w magnitudes ranging from 4.0 to 7.1, have been analyzed to study the dependence of peak ground motion parameters on magnitude, distance, regional and local site effects, through attenuation relationships. We first found that, for both pga and pgv, the attenuation relationships decay faster with distance for the vertical component than for the horizontal component. Also, the attenuation relationships decay faster with distance for the vertical pga than for the vertical pgv. We further compared the attenuation relationships for three subregions (chy, iwa, and nto) and the whole Taiwan region (twn). It is found that the chy area has higher ground motion, either in pga or pgv, than the other areas, especially at near-source distances. This is because the chy area is located on a thick, recent alluvial plain. Comparison of our new attenuation relationships with strong-motion data from the 1999 Chi-Chi earthquake ( M w 7.7) and the 2003 Cheng-Kung earthquake ( M w 6.8) shows that the attenuation relationships developed for M w ≤7 can be extrapolated to make reasonable estimates of strong motion from larger M w ≥7 earthquakes. Finally, we analyzed the residuals to investigate variations of pga and pgv with respect to site conditions. The results show that (1) the residual contour maps, especially for the pgv, have high consistency with the regional geology and topography of Taiwan. (2) The pgv residual contours reveal that Taipei Basin, Changhua Plain, Chianan Plain, Pingtung Valley, Ilan Plain, and Taitung Longitudinal Valley have high residual values. Note that most major metropolitan areas all fall in high residual areas. (3) The site classification based on geologic criteria by Lee et al. (2001) can be simplified into three classes, that is, class E for soft soils, a combination of classes C and D for dense and stiff soils, and class B for rocks. These three site classes are mostly distributed, respectively, in the alluvial plains at an elevation less than 50 m, in terraces and hills at an elevation less than 1000 m, and in high mountainous areas.

Mapping the soil resources of a recent alluvial plain in Greece using fuzzy sets in a GIS environment

Mapping the soil resources of a recent alluvial plain in Greece using fuzzy sets in a GIS environment

Mapping the soil resources of a recent alluvial plain in Greece using fuzzy sets in a GIS environment

SummaryCollecting soil data is time‐consuming and costly, often exceeding practical possibilities. A methodology for the delineation of soil mapping units in an alluvial plain of Western Peloponnese, Greece, was investigated. A detailed soil survey of an area of 300 ha was used to obtain the basic soil data for evaluating the performance of the proposed methodology. The methodology consists of the following steps: (a) data collection from borings and representative soil profiles, (b) definition of the soil mapping units in the study area, (c) determination of the range of the diagnostic variables for each mapping unit from field observations and statistical analysis of the analytical data from representative soil profiles, (d) determination of the class of each diagnostic variable by observation at a network of boring points, (e) subjective assignment of numerical values to soil variables at the bore points, (f) estimation of the values of each soil variable at the points of a regular grid using the interpolation methods kriging and inverse squared distance, (g) application of the fuzzy set theory to the interpolated data and the production of thematic fuzzy maps, and (h) validation of the results through a number of independent test borings. The results obtained show that the proposed methodology can produce soil maps of recent alluvial plains with acceptable accuracy and cost.

Cracking in recent alluvial soils as related to easily determined soil properties

Cracking was studied in fifty soils located in two recent alluvial plains and it was related to soil parameters such as clay content, soil moisture content, bulk density and coefficient of linear extensibility (COLE). The total crack area per unit soil surface, the crack width and crack depth were measured by tracing them on transparent sheets. The rate of crack development was also studied in a soil immediately after irrigation. Results showed that crack width increased initially almost linearly with decreasing soil moisture content to a certain level and then increased in a declining rate until a maximum width was attained. Cracks appeared on the soil surface after water was removed from the large soil pores. The total crack area occupied a significant portion of the soil surface reaching a maximum value of 22.7%. Measurements of water flow into the cracks during irrigation were significant and in some soils exceeded the conductivity of the uncracked soil surface. An empirical relation was found, which calculates the total crack area per unit soil surface as a function of clay content, COLE and volumetric moisture content. The average crack width was linearly related to the total crack area measured on the soil surface. Furthermore, the crack depth in the plow layer was logarithmically related to clay content, COLE and moisture content.

Satellite remote sensing in soil resource inventory of Dibrugarh district (part), Assam

Remote sensing techniques have been employed to identify and delineate soils in a part of Dibrugarh district of Assam. Landsat-4 MSS data in the form of FCC (4, 5, 7) were interpreted visually for physiographic analysis in conjunction with Survey of India topographic maps. Ground data were translated in terms of soils using composite interpretation map as base. The abstraction level attained was Families of Soil Taxonomy. Four major physiographic units were delineated, viz. active flood plain, recent alluvial plain, gently undulating old alluvial plain and gently sloping to undulating piedmont plain. Dominant soils identified are: coarse loamy Aeric Fluvaquents and fine loamy Typic Udifluvents in active flood plain; fine Typic Haplaquepts and fine loamy Aquic Dystrochrepts in recent alluvial plain; fine loamy Umbric Dystrochrepts and fine Ultic Hapludalfs in old alluvial plain; coarse loamy Typic Udorthents and fine Mollic Hapludalfs in piedmont plain.

Progress of the Quaternary Studies on the Recent Alluvial Plains in Japan

Progress of the Quaternary Studies on the Recent Alluvial Plains in Japan

Geomorphic Development of the Chita Peninsula, Aichi Prefecture

The Chita Peninsula, situated between the Mikawa Bay and the Ise Bay, is divided into following seven ladnform surfaces (recent alluvial plain is excluded). Morozaki (60-120m in altitude), Taketoyo (45-87m), Yokosuka (40-60m), Kamezaki (25-50m), Handa (10-30m), Iwaname (7-20m), and Ogawa (3-20m).Morozaki and Yokosuka surfaces are erosional surfaces of low relief, Taketoyo is a depositional surface formed as the fan-like flood plain, and others are coastal and river terraces. The author supposes that Morozaki surface was formed in earlier Pliocene, Ogawa surface was in Holocene, and others were in Pleistocene.Judging from the inclination of Morozaki surface and the crossprofile through land and sea-bottom, the southern part of the peninsula is a tilted block. From the distribution pattern and the undulatory deformation of Taketoyo surface, the central and northern part of this peninsula made the folded type movement with the axes of N-S direction.On the other hand, Taketoyo surface may be correlated to Yagoto surface in the Nobi plain and Miyoshi surface in the Nishi-Mikawa plain. From these affairs, the author also supposes that the Nobi plain had been connected with the Nishi-Mikawa plain through the Chita peninsula at the stage of Taketoyo surface formation. Kamezaki, Handa, Iwaname and Ogawa surfaces were formed during the stage of high sea level and the altitudes of estimated ancient shore-line are about 30-40m, 10-15m, 7-10m, and 5m.

Growth of Alluvial Plain and Land Development in the Lower Basin of the Naka River

From the point of view that the recent alluvial plains are formed by running water and man's activities, the writer made a thorough investigation of the Naka River's deltaic plain in order to survey the growth of plain and the development of the plain.The result can be summarized as follows:1) Plain of the lower Naka has 10 topographical features. The fan surface is composed within the sphere of a circular arc (semidiameter: 6km) traced with Kami Ono as the vertex, and delta higher and delta lower lie in the margin. The former occupies the central part of plain, the latter is developed mostly on the delta side, excepting some lines radiately stretching in the central plain. Beach ridge and sand shore are largely growing at the advancing shores, but in the retreating shores they could not be found.2) At the time of the last glacial age, this region was covered all over with depesits of coarse gravels and formed a fan land which had moresteep slope than the surface of present land; later, clayey soil beds (about 10m deep) were deposited as the result of submergence. The basis of plain was gradually formed with the submergence after the middle part of Jomon Age. There were two old distributary channels, at first, flowing from the hills towards the north-east by east and the south-east by east. Therefore, alluvial action in this region had its origin in depositing on the delta side. With natural agency and artificial activities, after that, these channels changed by slow degrees their courses from west to east. Then the deposition in the central part of plain began. The number of distributary channels has become larger on the north side of the present course. This may be attributed it diastrophic movements in the direction of SW-NE. The changes of shore line are conspicuous on the north-side of the mouths of principal dis tributaries. Though the shore line that links river mouth and Wada Jima (lies to the north; not island) had taken a shape of convex about two handred years ago, it became to be in straight-line about 1870 and shows a concave shore line at present.3) In ancient times, the development of land reclamations on clearing was set forward around delta side, and in the Middle Ages it was gradually expanded into the central part of plain. The development of tidal land is characteristic of the Tokugawa-era, and nowadays the reclaiming work is kept on to make a new arable land at the rising part of delta.4) The land development in ancient times was selective, and in the Middle Ages the land utilization was made according with physical formation. The development in the Tokugawa-era, however, is getting to urge the slow physical development of plain. This artificial urging of development began from about 1750. And at present the inhabitants are reclaiming the foreshore from the sea.In short, the developments in ancient times and the Middle Ages were passive, leaving itself to circumstances; men were in the situation of being acted upon. In the Tokugawa-era and present times, on the contrary, challenges to the circumstances are being made actively.Not that the plains keep a record of the victory of man's activities over the physical history. In the Middle Ages, the land system of Jori type buried in the ground, and breaks of Bandai artificial levees and the other breakwaters shows a case of a temporary defeat of human history in the Tokugawa-era. Even now, shore lines are gradually receding because of erosion. The land depression attributable to earthquakes is increasing the damaged districts from sea-water.Concerning the study of recent alluvial plains, there is much that requires consideration from various angles in human activities.