Assessment of Natural Self Restoration of the Water of Al-Mahmoudia Canal, Western Part of Nile Delta, Egypt

摘要

Al-Mahmoudia canal in northern edge of Beheira Governorate, west part of Nile Delta, has important role in the economic development and prosperity of the people in Beheira and Alexandria Governorates. It has been exploited to support agriculture, fisheries, public water supply, industry, hydroelectric power and recreation. The continuing deterioration of water quality in the canal has become a routine water pollution case. Therefore, it is necessary to solve the canal pollution problems and upgrade the water quality. The objective of this study was to characterize and understand the water quality of Al-Mahmoudia canal. Samples of water were collected monthly from eleven locations for 12 month during 2010-2011. In situ measurements included; Temp, TDS, pH and DO, and laboratory determinations included TSS, BOD5, COD, NO- 3, NH4 +, TC and FC, in addition to Cd, Cu, Fe, Mn, Ni, Pb and Zn. Natural self-purification model based on oxygen sag curve introduced by Streeter and Phelps was applied. The obtained results showed that the majority of water quality problems of Al-Mahmoudia canal are due to receive low grade water quality of Rosetta Branch. Natural self-purification is calculated and observed in two cases. The first is normal case, which no drainage water is discharging into Al-Mahmoudia canal; hence, Edko irrigation pump station is stopping lift drainage water of Zarkon drain into the canal. The result of this case showed that the deoxygenation rate is higher than the reoxygenation rate from km 14 to km 17.87 of Al-Mahmoudia canal. The second is simulated case, which simulated Edko irrigation pump station is lifting drainage water of Zarkon drain into the canal. The result of this case showed the deoxygenation rate is higher than the reoxygenation rate from km 14 to km 18.06 of the canal and the reach need 10.83 km to get rid of the influence of pollutants from Edko irrigation pump station discharge. The difference between conceptual and pragmatic approaches was used in identifying the most polluted reaches by non-point pollution sources along the canal. According to the obtained result the difference between observed and calculated values in the watercourse from south to north direction has been increased and contribution of the nonpoint pollution sources at Al-Mahmoudia canal is related to the four reaches.