Methodology - Response of Flood Events to Land Use and Climate Change - page 91

and negative U(t) denotes a negative trend. In this study, a was set at 0.05. The
sequential version test enables detection of the approximate time of occurrence of
a trend by locating the intersection point of the forward and backward curves of
the test statistic. If the intersection point is significant at a a ¼ 0 : 05 ; we infer that
the critical point of the analyzed time series occurs at that time [ 129 , 130 ]. Hence,
the Sequential Mann-Kendall test is considered an effective way of locating the
beginning point of a trend [ 128 ].
3.13 Land Use Change Modeling
The first category of anthropogenic effects results from human actions on the
ecosystems, such as deforestation and urbanization. These lead to changes in the
ecosystem that magnify the consequences of heavy precipitation, converting this
precipitation into floods of a greater severity than otherwise would have resulted
IAEA/WMO [ 132 ]. Monitoring land use changes provides urban planners and
decision makers with essential information about past and current states of
development and the nature of changes that have occurred [ 122 ]. It is generally
accepted that changes in land use patterns (e.g., expansion of settlements including
road construction, deforestation, distinct practices in arable and grassland man-
agement) contribute to an increased frequency and severity of flood generation
[ 123 ]. Development of land from forested cover to investigating pasture is known
to increase the rate and the total volume of runoff during storm events [ 124 , 125 ],
Rowe [ 132 ]. Such land use changes results in higher flood peaks, and greater
fluctuations in flow and water levels [ 126 ]. In this study, the data sources included
were aerial photographs for the years of 1956, 1974, 1982, 1995, 2000, and 2004.
The land use maps were digitized based on these available aerial photos. ArcGIS
package was applied to detect the changes from 1956 to 2004. A geographic
information system offered the possibility of structured data management and data
access as well as efficient and objective analysis procedures. In light of these
considerations, the present work aims to propose a statistical analysis for
the assessment of the land use change over the time and find any probable effect on
the flow propagation of the Ubaye River.
3.14 Chapter Summary
This chapter has described the methodologies applied in this research and intro-
duced all the procedures in detail. For quality control of the DEM, different
interpolation techniques were introduced and it was also explained how the results
might be analyzed both statistically and hydrologically. Then, it was explained
how the spatial and temporal input data such as discharge, RAS-Geometry data
and cross sections were prepared for hydrodynamic simulation purposes. In the