Geoscience Reference
In-Depth Information
Fig. 5.5 Examples of unsupervised classification in Herzliya basins. (a) Herzliya industrial area,
(b) School residential basin
Table 5.2 Storm runoff coefficients in residential and industrial areas on the coastal plain
Storm runoff
coefficient
Ra'anana 10 3 0.26
Residential Ashdod - Tel Ashdod 4 3 0.30
Ashdod average 12 3 0.3
Herzliya open tunnel 4.2 3 0.32
Herzliya closed tunnel 1.4 2 0.46
Ra'anana industrial 0.086 2 0.86
Industrial Ashdod industrial 3 3 0.3
Herzliya industrial 0.22 2 0.68
Note: Ashdod's industrial area is made up of old styled buildings and is significantly different in its
percentages of impermeable areas
Period of
observation (years)
Basin area (km
2
)
Area use
Basin
For the residential areas, it can be seen from Table
5.2
that except for Herzliya's
closed tunnel, the storm runoff coefficients are very similar in the order of 0.30.
This is to note that the ratio of runoff rain was observed for only a few years, which
did not necessarily include years of abundant rainfall. At this stage, it is the authors'
opinion that for the purpose of estimating water resources from urban residential
areas along the coastal plain, the average runoff differential of 0.33 can be used.
As expected, the runoff coefficient in the Ra'anana and Herzliya industrial areas
is much higher (0.84-0.68), which is why it is suggested to use the average runoff
coefficient as a very rough estimate of runoff quantities from industrial areas.
It should be pointed out that these coefficients are average values for each of the
sub-basin in the urban area. No distinction was made between areas contributing
high quantities of runoff such as buildings, sidewalks, parking lots and roads and
areas where the runoff is lower, such as yards, gardens, public areas, parks and open
areas.
