|Name of the Student||:||Mahmoud Musaffar
|Name of the supervisor/s||:||Dr. Nidal Mahmoud
|Title of the thesis||:||
Rainwater Harvesting for Domestic uses in two Palestinian Rural Areas with Emphasis on Quality and Quantity
Rainwater harvesting becomes an appropriate solution to minimize the water shortage in Palestine, especially in rural areas where water networks are not available or supplied water is inadequate. The quality of roof-top harvested rainwater which is used for domestic and drinking purposes in the middle area of the West Bank and the factors affecting it were assessed through wet season surveillance (from Nov., 2005 to April, 2006). The study conducted in Kubar and Abu Shekheidim villages in Ramallah district. The quality of harvested rainwater was assessed for 7 cisterns. The quantity of harvested rainwater and run-off coefficient were determined for 5 cisterns. 72 rainwater samples were collected from ferroconcrete and rock with cement lining storage cisterns (48–114 m3 capacity) tested in terms of physical, chemical and biological characteristics.
To assess the quality of rainwater (fresh and harvested), the following parameters were measured: a) Physical parameters: pH, Dissolved Oxygen (DO), Temperature (T), Electrical Conductivity (EC), Turbidity and Salinity. b) Chemical parameters: Total Hardness as (CaCO3), Calcium (Ca++), Sodium (Na+), Chloride (Cl-), nitrate (NO3-) as well as the heavy metals: lead (Pb), Chromium (Cr) and Zinc (Zn). C) Biological parameters: Fecal Coliforms (FC) and Total Coliforms (TC). Lab results on harvested and fresh rainwater samples showed that the samples were alkaline with pH values above 8. This is postulated to the alkaline dust from soil and rock type in this area which is mainly lime and delomite. Also, the results showed that rainwater have very low concentration of TDS of less than 68 mg/l for fresh water samples and below136 mg/l for harvested ones. The turbidity had varied remarkably for the same cistern over time. Some samples had turbidity above 10 NTU while its values went down after storage then raised again due to the nature of rainfall based on atmospheric conditions; Turbidity test showed that fresh and harvested rainwater mostly did not comply with the Palestinian standards and WHO guidelines (exceeds 5 NTU) due to debris from badly managed rooftops. Also most harvested rainwater samples were found aerobic with DO values range above 6 mg/l while fresh water was more aerobic with DO more than 8.5 mg/l. Total and fecal coliforms were absent in fresh rainwater but its detected respectively in 100% and 86% of the tested harvested rainwater samples; so that the pollution came after storage due to bad management of the whole system and/ or from leakage from nearest cesspits. Samples of harvested rainwater showed low concentration of ions as Ca++, Na+, Cl- and total hardness while the results showed the NO3 concentration varied from cistern to another. This is might be due to several factors like the status of rooftop and the distance from cesspits. In the cisterns which are closer than 10 m from cesspits, the NO3 concentration was rather high probably due to ammonium leakage from these cesspits. Also, the results showed harvested rainwater is not contaminated with heavy metals like Cr, Zn and Pb as the measured values fell within the PS41 and WHO guidelines.
The Run-Off Coefficient (R) as an important design parameter was calculated based on the analysis of rainfall data and technical aspects for these systems. Results revealed that this coefficient is extending from 0.70 to 0.90 for Ferro-concrete catchments which considered the most common type of catchments in Palestine.
This study also highlights the uses of rainwater harvesting systems for providing an additional domestic water source from which to meet local water needs. To use rain water harvesting as a domestic source; systems must be well managed and disinfection should be applied into the cisterns but under direction of Ministry of Health or related institutions in order to avoid by-products formation.