The Southern part of Osaka Plain is one of the regions which has a great many irrigation ponds for paddy-fields. In many geographical writings, one often comes across the statement saying quite simply that it is because this region is an area within the Inland Sea, or the Seto-uchi region, with the least rainfall, that there are many ponds. But the authors do not agree to such an opinion. They consider the reason for the numerous ponds found in the region to be as follows: All the rivers in this region are short and have small catchment areas where there are no high mountains to cause rainfall. But the total area of paddy-field in the river valleys is large for the size of the rivers; therefore the paddy-fields of the region cannot get enough irrigation water from the river source only.
In Japan, wherever river water is insufflcient, irrigation ponds or wells are made use of. So we made an inquiry as to which of the two facilities is better suited for this region. As a result of our study, we have discoveredt hat since this plain is occupied for the most part by diluvial upland with a slight gradient where the soil has small permeability, and moreover, it is surrounded by hills where there are many sites for ponds, it is easier and more advantageou to construct irrigation ponds than to dig wells. As a matter of fact, it has been found that there is need for such irrigation facilities as ponds in this region, and that the topographical features are also suited for making ponds. Hence the pond irrigation has developed.
In order to work effectively, however, irrigation ponds must be easily supplied with water. But judging from map reading only there are many ponds which seem to be very difflcult to collect water. The means of collecting water seemed to be a most interesting problem for the authors; so they selected and studied three characteristic districts_??_the northern part of the region east of Sakai City, the Makio River Valley, and the Kashii River Valley.
The catchment area of the northern part east of Sakai City is the smallest one on this plain, so the possibility of collecting water for the ponds is greatly limited. As a result, the farmers, when transplanting rice, must wait for the rain of the so-called “bai-u” or the rainy season, which begins from between the 10 th to the 20 th of June and lasts until the 1 st to the 10 th of July.
In the Makio River Valley, the river and ponds co-operate to supply irrigation water.
In the Kashii River Valley, there are three characteristic areas. One is preferentially supplied with water from the ponds in the hill-land which easily gather river water ; the second is supplied with water from shallow, dish-like ponds on the plain where it is difficult to gather water ; and the third utilizes under-ground water and river water in addition to pond water.

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This study suggests that an area of sand bar is originally an area abundant in ground water resource, but in developing this resource, there uill caused such troubles as scarcity of well yields and salt water encroachment.
The findings and conclusions in Hachirogata area (Akita Pref.), Miho area (Shizuoka Pref.) and Yumigahama area (Tottori Pref.) are summarized as follows:
At the north-western side of Hachirogata, there extends a sand bar, which is 10 km long, 2 km wide and 5 m at altitude on the south, 20 m in the middle and several ten meters on the north. Lake Hachirogata is separated from the Japan Sea by this bar covered by sand dune.
According to the results from topographical, geological, electrical resistivity survey, seismic prospecting and test borings, the following layers are distingushed:
Formation Age Permeability (K) Depth to the lower
cm/sec limit (below s. 1.)
Wakimoto F. Pliocene l×10^-7 -
Shibikawa F. Pliocene_??_1×10^-4-1×10^-6 100-250m
Katanishi F. Pleistcene_??_clay 1×10^-7 Hachirogata F. Hollocene_??_sand 1×10^-4-1×10^-5 sand dune 1×10^-3 max. 70m Judging from ρ-a curve, sea water invades through pervious buried valley on Pleistocene deposits.
At Miho Sand Spit which extends from Udosan (Kunosan) Hill eastward is considerd as a prolonged forked sand spit. A sand and gravel layer which makes principal aquifer of this region is underlaid with less permeable sand and silt layers of plaistocene age which compose Udosan Hill. The ground water body in this aquifer is separated into three parts, Kuno area, old spit area and new spit area. At inner bay area which has a thicker sand and gravel layer or younger spit area, influence of tidal fluctuation on the ground water level is conspicuous and there forms Herzberg's lens.
At Yumigahama sand bar, alluvial deposit of 70m (max. value) is found on the pleistocene basalt or tertialy formation by electrical resistivity survey and test borings.
The alluvium is devided into three, upper fine sand layer, next silty layer containing volcanic ashes and basal gravel layer. The silty layer is saturated with saline water and acts an cap layer to the underlying gravel layer which contains methan gas. Such condition above mentioned modifies the form of Herzberg's lens of this region.
Fresh grouned water which is believed to be furnished mainly by artificial irrigation canal, Yonekawa, during irrigation period, flows in the uppermost fine sand layer and the motion of this water is restricted by the shape of an underlying silt layer.

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Bei Berücksichtigung regionaler Gegebenheiten, wie z. B. Verkehr, Bevölkerungsdichte oder Lebensstandard, wind das schematisch-hierarchische System der zentralen Siedlungen, wie es bei W. Christaller auftritt, getrübt oder abgeändert. Der Verfasser hat im Untersuchungsgebiet des Regierungsbezirkes Hiroshima, das sich in je ein Festlands-, ein küsten- und ein Inselgebiet unterteilt, festzustellen versucht, wie sich der Landschaftscharakter dieser Gebiete auf die Verteilung der zentralen Siedlungen und ihre Entwicklung auswirkt. Das Ergebnis kann folgendermassen zusammengefasst werden:
1. Aufgrund einer Analyse der zentralen Einrichtungen wurden die zentralen Siedlungen zunächst klassifiziert, was jedoch keine klassifizierung Zentralität hinsichtlich des Unterschieds im b/n-Verhältnis der Dienstleistungen in einzelnen Orte bedeutet ; im Küsten- und Inselgebiet überwiegen die Städte, deren Zentralfuktionen als Industrie- oder Wohnstädte gering sind. Es hat sich daher gezeigt, dass die Direktuntersuchungsmethode in diesen Gebieten nicht anwendbar ist. Im Verkehrsbereich kann vielleicht an ein Schema wie Karte 9 gedacht werden.
2. Um die Verteilung der zentralen Siedlungen dynamisch beobachten zu können, wurde das erste Familienregister aus der frühen Meiji-Zeit (Jinshin-Koseki/aus dem Jahre 1872) herangezogen. Danach herrschen auf dem Festland grösstenteils Entfernungen von rd. 16 km Luftlinie vor, die auch heute noch haüfig aufzutreten sind. Entwicklungsgeschichtlich betrachtet besteht ein Unterschied in der Grössenstruktur zwischen den zentralen Siedlungen in den entwickelten Küstengebiete und denjenigen im unterentwickelten Festlandsgebiete ; d. h. im Festlandsgebiet sind die Abstufungen geringer als im Küstengebiete. Bei den Entwickelungsfaktoren fällt auf, dass im Küstengebiete mit nahe beieinander liegenden zentralen Siedlungen die kleineren Orte infolge des Konkurrenzkampfes mit den durch die Industrie entwickelten Orte zurückgedrängt wurden. Im Eestlandsgebiete herrschen dagegen die durch Verkehrswege oder den Sitz der Verwaltung bedingten Entwicklungen vor. Beide Gebiete weisen also einen graduellen Unterschied in der Entwicklung auf. Bei der Entwicklung der hierarchischen Systeme auch infolge Besserung der Verkehrsverhältnisse besteht die Neigung, dass grosse Küstenzentren den Hilfs-und marginalen Zentren in der Nähe die Zentralfunktionen entnehmen, und dass gleichzeitig mit den wachsenden singulären Funktionen die Eingeständigkeit der Hilfszentren von der Verwaltung der grossen Küstenzentren zunimmt.

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