SUBSURFACE HYDROLOGY OF LAYERED COLLUVIUM MANTLES IN UNCHANNELLED VALLEYS - SOUTH-EASTERN BRAZIL

被引:29
作者
FERNANDES, NF
NETTO, ALC
LACERDA, WA
机构
[1] FED UNIV RIO DE JANEIRO,INST GEOCIENCIAS,DEPT GEOG,BR-21941590 RIO JANEIRO,BRAZIL
[2] FED UNIV RIO DE JANEIRO,COPPE,PROG POSGRAD ENG CIVIL,BR-21941590 RIO JANEIRO,BRAZIL
关键词
SUBSURFACE HYDROLOGY; SOIL EROSION; TENSIOMETERS; UNCHANNELLED VALLEYS;
D O I
10.1002/esp.3290190703
中图分类号
P9 [自然地理学];
学科分类号
0705 ; 070501 ;
摘要
The effects of subsurface hydrology on the evolution of erosive processes inside layered colluvium mantles in unchannelled valleys are investigated. Tensiometer nests are installed in different morphological conditions with their specific depths controlled by the subsurface structure of the colluvium mantle. Daily readings (during one year) and physical and mechanical analyses of the different colluvium layers are carried out. In spite of a highly discontinuous subsurface structure, present topography is the major factor controlling subsurface how in this landscape. Paleotopographic features, usually resulting from the lateral mobilization of the previous topographic hollow axis, can locally control the preferential expansion of the saturated zone towards areas other than the present hollow axis. During rainy periods, pressure head at the base of the hollow axis increases towards a maximum value which is not increased by subsequent precipitation inputs. New water input is dissipated by direct precipitation onto the saturated zone and exfiltration by seepage at the gully head walls, precluding the development of the excess pore pressures required to trigger failure by landsliding.
引用
收藏
页码:609 / 626
页数:18
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