Theoretical Background - Response of Flood Events to Land Use and Climate Change - page 30

intensive land use change, such as the construction of roads close to the rivers in
mountainous areas (as a type of land use change and anthropogenic activity), can
induce on the river runoff which then increase [ 105 ].
These studies highlighted that the hydrological effects of human activity are
strictly dependent on the extension of the area affected by the man made inter-
vention. For instance, similar analyses were performed in a tropical watershed by
Costa et al. [ 106 ]; he realized that a deforestation of about 30 % in the basin
induced a 24 % increase in annual mean discharge. Therefore, it might be con-
cluded that land use change, in particular deforestation, has been credited with
causing important increases in the frequency and severity of flood events. In
another simulation, the research performed by Brath and Montanari [ 107 ], the
higher sensitivity to land use change of the low flows has been also investigated.
Recently, Naef et al. [ 108 ] reached similar results and conclusions by addressing a
river basin located in Germany. They found that the flood runoff reduction by land
use change can be remarkable in the presence of rapid run-off production only. In
the last two decades, a lot of research has been carried out to estimate the effects
on the hydrological cycle induced by vegetation cover changes, with particular
emphasis on deforestation consequences [ 109 ], urbanization of bottom valley areas
[ 110 ], construction of roads in forests [ 111 , 112 ], and conversion of wooded areas
to pasture [ 113 ]. In recent decades, the scientific investigation shows that a lot of
inundation has occurred in Europe causing loss of human lives and financial
damages which have been aggravated, in several cases, by the intense urbanization
of flood-prone areas [ 114 ]. Based on the European parliament's report, land-use
changes in Europe have lead to a reduction in the storage volume and an increase
in the run-off coefficient. Sullivan et al. [ 115 ] studied a basin in Cornwall which
had a significant increasing trend in magnitude and frequency of flood flows, but
only a weak decreasing trend in rainfall. Although they suggested that the
increasing in flood flows could be attributed to land-use change. Other researchers
have also suggested that this interaction of different forcing factors could be
exploited, for example by offsetting urbanization with forestation, or climate
change by land-use change [ 108 , 116 , 117 , 118 ]. The effect of land-use change was
studied also by Bultot et al. [ 119 ], who analyzed the influence of land use on the
water balance of the near surface soil layer by applying a conceptual rainfall-
runoff model to a Belgian river basin. They concluded that the presence of veg-
etation can induce effects on the river flows that are more evident in arid climates
where the vegetation cover causes a reduction of the river discharge that is more
marked for the lower river flows. Increases in urban areas tend to increase the
responsiveness of an area to a rainfall event, usually leading to flash flooding and
increased maximum rates of stream flow. Infrastructure planning and implemen-
tation, as part of a regional development plan of an urban area, contributes greatly
to

mitigate damages of flood events. It should be considered that while