Acid rain has been a big problem for urban area during recent decades. Acid rain comes from high concentration of air pollutant, including man made or artificial and natural, in the atmosphere. As the biggest religious town in Iran, Mashhad also...

Water scarcity is a major problem in developing countries. Rain water has been valued

for their purity and flexibility. Rainwater, resolutions on the merits of the gathering,

transmission and storage of rain water there. The scope...