metropolitan cities; opportunities and challenges, case study: holy city of mashhad

in recent years, dousti dam has been one of the most important mashhad’s sources of drinking water. in this way, 500 million cubic meters of the outflow of the dam enter into the mashhad watershed. with the arrival of this volume of water, the drinking water wells in the city were turned off. on the other hand, the development of some urban infrastructures such as the sewer collecting network did not construct along with other urban developments. as a consequence, the water entering the aquifer has caused the localized water level increasing, especially in the central areas of the city, which imposes some problems for other urban development. in the present study, more than 111 piezometric wells were selected to analyze the groundwater level fluctuations in the period between december 2013 to august 2014 and then groundwater level contours were generated in order to study the spatial and temporal changes in groundwater levels in the study area. the results showed that groundwater levels increase, locally, in some areas of the city. the results of these investigations were discussed during some meetings with the contribution of experts from all relevant government agencies, university professors and experts, which yielded important decisions for how to deal with this phenomenon. in order to reduce the risks of the groundwater level increasing, the drinking water wells were turned on during the winter of 1392 and spring of 1393. therefore, the groundwater levels were controlled. some notifications were made by considering the decisions of the aforementioned meetings, so fortunately any failures of buildings and facilities caused by the phenomenon were not reported. the results obtained from field data as well as the opportunities, challenges and management conditions are studied in the following sections.