Geoscience Reference
In-Depth Information
The increasing of impervious areas and the addition of pollution sources from the
urban domain, have a negative effect on water resources.
Combining land-use/land-cover data from remote sensing and GIS with quantity
and quality information from urban catchments may help to bridge this gap and
generalize relationships between fundamental hydrological and land-use parameters.
Increased impervious surface area is a consequence of urbanization, with correspon-
dent and significant effects on the hydrologic cycle (Zheng and Baetz
1999
;Shuster
et al.
2005
; Goldschlager et al.
2009
). Carmon and Shamir (
1997
) estimated that the
built-up areas above the coastal aquifer would double by 2020, in comparison to the
extent of built-up areas in 1990, and would reach about 500 km
2
. These areas would
cover approximately 26% of the coastal plain with an impermeable covering, a fact
that would affect the ability of the coastal aquifer to continue to be a major source
of water for Israel's. Most of the expected increase noted will be in residential
neighborhoods (331 km
2
,comparedwith162.7km
2
), together with a decrease of
two-thirds of the cultivated farm land of the coastal plain (from 929 to 361.8 km
2
).
Various research studies in Israel and around the world point to the fact that
urbanization activities lead to immediate occurrence of some processes effect the
water cycle. Urbanization of rural areas is known to directly affect drainage basin
hydrology (e.g. Dunne and Leopold
1978
; Hollis
1988
; Lazaro
1990
). Paving the
landscape with impervious materials means that a much larger proportion of any
rainfall forms immediate runoff. In general, after major urban development in
a drainage basin: (1) a higher proportion of rainfall appears as surface runoff,
(2) the total volume of discharge increases, (3) for a specific rain event, the response
of the watershed is accelerated with a steeper rising limb in a hydrograph, (4) lag
time and time to peak are reduced, (5) flood peak magnitude is increased, (6) higher
erosion rate of river beds and channels passing through urban areas and (7) water
quality in streams and aquifers draining urban centers is typically degraded
(Wolman and Schick
1967
; Dunne and Leopold
1978
; Marsalek and Torno
1993
;
Kang et al.
1998
; Asaf et al.
2004
; Bormil et al.
2003
; Nativ et al.
2001
;
Goldschlager et al.
2005
,
2009
). Human activity in urban areas increases the load
of dust, sand, nutritional materials, decomposed organic materials, toxic organic
compounds, heavy metals and bacteria on land surface. Consequently, surface
water is likely to get contaminated (Flores-Rodriguez et al.
1994
). As urban runoff
is comprised of many individual flow components draining various areas, the “mix”
at the outlet depends on the characteristics of those areas, pollutant wash off
potentials and the features of the specific rain event (Pitt et al.
1999
).
Urban areas have been classified in the literature into main roads (including
parking lots and airports), roofs, residential areas, commercial areas, industrial
areas, parks and lawns, and open, undeveloped areas, all of which generate
stormwater of different quality. Roads, parking lots and gas stations have been
known to contribute a large variety of contaminants, directly related to vehicles
(hydrocarbons, oxides of nitrogen, sulfur and lead) or salt de-icing (halite)
(Bannerman et al.
1993
; Hermann et al.
1994
; Smith et al.
2000
). The high level of
pollution found on major arterial roads in urban areas and highways has been
correlated to traffic density (Shinya et al.
2000
).
