Journal of Geography (Chigaku Zasshi)
Online ISSN : 1884-0884
Print ISSN : 0022-135X
ISSN-L : 0022-135X
Volume 80 , Issue 3
Showing 1-7 articles out of 7 articles from the selected issue
  • Hisashi TAJIMA
    1971 Volume 80 Issue 3 Pages 133-159
    Published: June 25, 1971
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    One of the most striking aspects of the movement of population in Peru is the migration from Andes highland the “Sierra” to the coastal region.
    In the Sierra of Central Andes of Peru, there are many indian peoples, living on self-sufficient agriculture. The great number of them moves to the coastal region.
    The traditional safety value for the surplus population of the Sierra has been the irrigated oasis of the desert coast. But in few decades migration from the Sierra has far exceeded the absorptive capacity of the coastal plantation, and has been directed increasingly toward the coastal cities particularly Lima, capital of this country.
    Major concentrations of the population occur around Lima city. They come from the whole country not only from Andes highland, but also from the coastal region. The slums that ring the capital city are conclusive evidence that the urban habitant is incapable of accommodating the surplus population.
    The altitudinal point of view, the surplus population at the elevation higher than 2, 500 m moves to the coastal region lower than 1, 500 m, but yet population of highland are increasing slowly.
    The smaller though significant, movement has been taking place from the Sierra to the upper tropical Amazonas region, “Selva” lower than 1, 500 m. The main concentrating region of population are Lima, Callas, other coastal cities (Trujillo, Chiclays, Chimbote, Arequipa) and small cities in central region of Andes highland.
    On the contrary, the main emigrating region are Andes highland and the most of the coastal cities. From the coastal cities, many people migrate to Lima, but from the Sierra near by, surplus population flow to these cities, and the population of these cities has been increasing.
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  • Takeshi MIZUTANI
    1971 Volume 80 Issue 3 Pages 160-178
    Published: June 25, 1971
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The mechanism of slope erosion and the process of slope formation have been studied by physical and morphometrical analysis.
    In the previous study, a fundamental equation on slope erosion
    E=Klm (sinθ-sinθc) n (1)
    E : erosion depth at l
    l : distance from the top of the slope
    θ : slope angle k, m, n, θc : constant was derived by hydrological and physical considerations of erosional agents such as tracting force of flowing water and abrasion due to material of mass movement. Theoretical values of erosion depth obtained from equation (1) agree quite well with measured values at youthfully dissected strato-volcanoes in Japan.
    In the present paper, erosional landforms of several strato-volcanoes in the stage of early maturity were measured and averaged profiles of initial and present landforms and altitudinal changes of average amount of erosion depth were obtained. Multiple regression coefficients log K, m and n were obtained with each slope by the method of least squares. The values of m and n are nearly 1 at most of slopes out of relation to location, erosional stage and scale of the slope. Theoretical values of erosion depth calculated from equation (1) with determined coefficients have also good agreements with measured values at these fairly highly dissected volcanoes.
    The amounts of undercutting of valley beds at volcanoes are also given by equation (1). Theoretical basis of this agreement was obtained by physical consideration of erosional processes.
    Equation (1) was derived supposing uniform sheet erosion all over the slope. This supposition, however, does not hold at highly dissected slope. The reason of applicability of equation (1) to highly dissected volcanoes can be explained by assumptions that erosional process at valley bed is dominating and the recession of valley wall proceeds in proportion to the amount of undercutting of valley bed keeping the gradient of slope almost constant.
    Equation (1) can also be applied with success to the process of slope formation of abandoned coal slag heaps which are dissected by gullies. Thus, applicability of equation (1) to some of non-volcanic slopes was ascertained.
    Gradient of the lower end of the slope where radial valleys nearly disappear decreases as dissection of the slope precedes. Then, θc is not a constant but a function of E.
    Gradient and curvature of slope are thought to be regulating factors of slope erosion.However, multiple regression coefficients of these terms are entirely insignificant at several slopes. Gradient and curvature of slope are infered to be local and temporary factors.
    From modifying equation (1), the following equation of slope development is derived,
    ∂y/∂t=f1 (x, y) xm {∂y/∂x+g (t)} +f2∂y/∂x
    General process of slope development have been studied by solving the equation under various initial conditions.
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  • Akira SUWA
    1971 Volume 80 Issue 3 Pages 179-182
    Published: June 25, 1971
    Released: November 12, 2009
    JOURNALS FREE ACCESS
  • Lowell J. DAVID
    1971 Volume 80 Issue 3 Pages 183-191
    Published: June 25, 1971
    Released: April 23, 2010
    JOURNALS FREE ACCESS
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  • [in Japanese]
    1971 Volume 80 Issue 3 Pages 192-194
    Published: June 25, 1971
    Released: November 12, 2009
    JOURNALS FREE ACCESS
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  • 1971 Volume 80 Issue 3 Pages 196
    Published: 1971
    Released: November 12, 2009
    JOURNALS FREE ACCESS
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  • [in Japanese]
    1971 Volume 80 Issue 3 Pages Plate1-Plate2
    Published: June 25, 1971
    Released: November 12, 2009
    JOURNALS FREE ACCESS
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