Evaluating and forecasting groundwater level fluctuations resulting from the development of sewage collection network in Kerman

Increasing groundwater level in urban areas has become a major concern worldwide. In many countries, the main factors of rising groundwater level include reducing groundwater withdrawals and reduction in manufacturing industries, irrigation water infiltration, leaking sewage system underground storage, and drinking water leakage. A comparison between groundwater level (1986-2016) in Kerman plain and Kerman city demonstrated two reverse trends; a drop in annual water level occurred in the plan while in the urban areas an increase in annual water level was noticed. Water level measurement in handy wells in some areas of Kerman shows that it increases from 6 to 25 m in the central area to the suburban areas of the city (new structures). Increasing the usage of drinking water in city area due to an increase in population and development of Kerman, along with underground canal obstruction such as Qanat, agricultural land use change, removal of operational wells and use of absorption wells result in an increase in water table within the city in the lack of urban sewage network. The rise of the water level resulting from the mixing of sewage water with groundwater, while contributing to aquifer contamination and decreasing the soil resistance, due to the fact that in some of the soil horizons of Kerman, the soil has a collapsible property , saturation of this soil horizon will cause soil collapsible and serious damage to urban structures. To evaluate the effect of the development of sewage collection network on groundwater level, the collected data such as pumping data, drilling logs of wells, water level data, and geophysical data were analyzed using GMS software in MODFLOW format. The results show that after the development of sewage collection network in central parts of the city, the groundwater level could be dropped from 5.5m to 18m above ground level.