|M.Sc Student||Haft Adi|
|Subject||Characterising Stormwater in Israeli Cities Kfar-Saba|
as a case study
|Department||Department of Civil and Environmental Engineering||Supervisors||Professor Eran Friedler|
|Full Thesis text|
Urban stormwater may be recognized as an alternative water source but also as a source of a wide range of pollutants. The quality of urban stormwater in cities along the Mediterranean coastline was found to be substantially affected by extended dry periods between sporadic winter rainfall events characterizing this climate. This study focused on the effects of different land uses on stormwater quantity and quality in Kfar-Saba, Israel as a case study. Using advanced monitoring equipment, assessment of stormwater quantity and quality was determined from mixed uses mid-size catchment along with three different land uses sub-catchments consisting of: residential, light-industrial and road across two rainy seasons. Due to long dry periods between each storm event along the rainy season, elements of first flush were found in several storms throughout the season and not only during the first rain storm of the season. The main catchment, with a size of 2.78 Km2 and a runoff coefficient of 0.22-0.24, produced 336x103 m3 of stormwater in the rainy season of 2016-2017 for rainfall of only 481 mm. A projection for the entire city of Kfar-Saba with an overall area of 14.17 Km2 and average yearly rainfall of 550 mm, is expected to produce 2x106 m3 of stormwater per year, one quarter of the annual water demand of Kfar-Saba city, which was around 8.6x106 m3 in 2016. The residential sub-catchment area represents 6.2% of the major catchment area as well as 6.2% of the stormwater measured at the outlet of the major catchment. However, although the area of the light-industrial sub-catchment consists 6.9% of the major catchment, it generated 14% of the stormwater measured at the outlet of the major catchment. Meaning, the volume of stormwater generated from the light-industrial sub-catchment was twice as high as the residential one, although both were similar in size. Further, stormwater from the light-industrial area was found to be much more polluted than stormwater from the residential area. It should be noted that quarter of that pollution originated from the rainfall falling over the industrial area. While the mean level of aluminum in the light-industrial sub-catchment was around 20 mg/L, in the residential and road sub-catchment it was around 10 mg/L; all far above the drinking water standard of 0.2 mg/L and similar behavior found with manganese, copper and chromium. The 2 Km section of road-55 with a total area of 0.58 Km2, which was the road sub-catchment monitored, with daily average of 60,000 cars, produced less pollution than reported by similar previous studies in Israel and abroad. The road sub-catchment stormwater was less polluted than the light industrial sub-catchment, yet with higher pollution than the residential sub-catchment. The stormwater runoff that was monitored at all the monitoring stations in Kfar-Saba did not meet the requirements of the Israeli drinking water quality regulations and therefore, it appears that the runoff in Kfar-Saba requires treatment before any use can be made.