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| Titel |
Urban hydrology in mountainous middle eastern cities |
| VerfasserIn |
T. Grodek, J. Lange, J. Lekach, S. Husary |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 15, no. 3 ; Nr. 15, no. 3 (2011-03-17), S.953-966 |
| Datensatznummer |
250012692
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| Publikation (Nr.) |
 copernicus.org/hess-15-953-2011.pdf |
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| Zusammenfassung |
The Mediterranean climate together with the type of urban setting found in
mountainous Middle Eastern cities generate much lower runoff yields than
previously reported and than usually estimated for urban design. In fact, a
close analysis shows that most of the rainwater remains within the cities as
a possible source for urban groundwater recharge. The present study examined
two locales – Ramallah, an old traditional Palestinian Arab town, and
Modiin, a new township in Israel – both situated on the karstic Yarkon
Taninim aquifer. This aquifer supplies the only high-quality drinking water
in the region (one quarter of the Israeli-Palestinian water demand), which is
characterized by dense populations and limited water resources.
This paper provides the first measured information on the hydrological effects of
urbanization in the area. It was found that the shift of the mountainous
natural steep slopes into a series of closed-terraces with homes and gardens
create areas that are disconnected from the urban runoff response. Roofs
drained into the attached gardens create favorable recharge units.
Mainly low-gradient roads became the principal source for urban runoff
already following 1–4 mm of rainfall. Parallel roads converted single peak
hydrographs towards multi-peak runoff responses, increasing flow duration and
reducing peak discharges. The remaining urban area (public parks, natural
areas, etc.) generated runoff only as a result of high-magnitude rainstorms.
All of the above conditions limited urban runoff coefficients to an upper
boundary of only 35% and 30% (Ramallah and Modiin, respectively). During
extreme rainstorms (above 100 mm) similar runoff coefficients were measured
in urban and natural catchments as a result of the limited areas contributing
to runoff in the urban areas, while natural terrain does not have these
artificial limits. Hence, the effects of urbanization decrease
with event magnitude and there is significant potential for urban groundwater
recharge. However, frequent low-magnitude rainstorms often generate highly
polluted stormwater in urban sewer systems and this water should only be used
with great caution. |
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