Cause for the rise of the groundwater level in the Ganzhou urban district and its surroundings, Zhangye City, Gansu, China and countermeasures for the prevention and control of its induced geohazards

The groundwater balance, hydrochemistry, environmental isotopes, meteorological-hydrological conditions, groundwater flow field and regional structural change in the Ganzhou urban district and its surroundings, Zhangye City, Gansu, have been studied. According to the study results, the authors think that the main cause for the rise of the groundwater level in the study area is that: as the aquifuge in Quaternary loose strata was disrupted by the earthquake, the NW-trending deep fault in the basement of the central zone connected with the Qilian Mountains became a water-transmitting conduit, thus increasing the leakage recharge, and the increase of groundwater recharge in the basin resulted in the extensive rise of the water level. The general idea of the scheme of controlling geohazards induced by the rise of the water level is that in order to yield the results of “lasting stability” we should implement the measures of horizontal drainage in the urban district and the measures of drainage by use of vertical pipes and wells in sectors where the precipitation problem of underground buildings in the urban district must be urgently solved and the worst-hit district in the northern part of the urban district.