Geoscience Reference
In-Depth Information
Chapter 3
Impact Assessment of Hydrologic
Attributes and Slope Instability
Abstract Quantitative geomorphology provides a systematic approach to the
analysis of a complex landscape of any size. The stability of the mountain slope
depends upon the prevalence of various hydrologic variables. In the present work,
the excess and de
cit moisture period in a year and its role in slope instability were
assessed studying rainfall and evapotranspiration. Study envisages that July and
August are the most consistent rainfall months of the year where the values of
co-ef
cient of variation are very low. The distribution of drainage and its evolution
has been studied to determine the drainage concentration over the slope surface and
their role in slope steepening and instability. To assume the slope saturation of
materials saturation, stream confluence points/junction points were studied for
individual sub-watersheds. The length of drainage per unit area and upslope con-
tributing area were analyzed spatially in connection to the landslide potentiality.
The existence of moderate drainage density may invite havoc slope failure on
convex slope segment. Greater the upslope contributing area, maximum is the slope
saturation and slope instability in the Shivkhola watershed. Some important
drainage basin parameters such as basin shape, form factor, circularity ratio,
elongation ratio, compactness factor, and elipticity index of the sub-watersheds
were considered to develop the priority scale on slope instability. The sub-basin I
and IV are more efficient in drainage and are more erosion and landslide prone
followed by sub-watershed V, II, III and VI.
Keywords Rainfall
Drainage morphometry
Landslide potentiality
Instability
rank
Watershed
3.1 Introduction
One of the most fundamental geomorphic unit is the
in the study of
geo-hydrological parameters where drainage network characteristics and its
evolution strongly influences the whole hydrological parameters through initiating,
'
drainage basin
'
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