The impact of climate change and water resources management on the groundwater volume and chemistry of the Neyriz Aquifer

Global warming and climate change have repeatedly led to droughts in arid and semi-arid regions such
as Iran. When these droughts are compounded by poor management of groundwater resources, severe
water crises occur. This leads to a deterioration of groundwater resources in terms of both quantity and
quality. The excessive abstraction of groundwater for human consumption, e.g. for drinking, industrial
and agricultural purposes, leads to a sharp decline in groundwater levels and ultimately to land
subsidence. This study deals with the effects of climate change and the mismanagement of groundwater
resources in the Neyriz plain. For the hydrogeological study, iso-potential and flowline maps from
September 1995 to 2020, iso-EC lines from September 1998 to 2020, and hydrographs and chemograms
of the aquifer were plotted along with Piper, Durov, Shoeller and Gibbs diagrams. The results indicate
an annual drawdown of 0.4 meters in the plain and a decline in water quality from 1998 to 2020. The
cross section along the aquifer in 1998 and 2020 reveals a reverse slope of the water level near the lake,
which has led to surface saltwater intrusion into the aquifer from the lake that increasing by about 175
percent from 1998 to 2020. Since there are no geophysical surveys in the area, the depth of the bedrock
was estimated based on the maximum depth of the nearby production wells. The volume of the aquifer
was calculated using ArcGIS software for each year from 1995 to 2020 and an empirical equation was
derived to predict the volume of the aquifer based on the water level of the plain in the present or in the
future. Based on the relationship between groundwater level, EC and volume of the aquifer, it was found
that the aquifer behaves differently when the level is above or below 1538 meters. It was found that
below 1538 meters, the lateral surface of the aquifer in the western part decreases sharply, reducing the
volume of the aquifer and increasing the infiltration of salt water from the lake. It is therefore
recommended to carry out artificial recharge in the Neyriz Plain to prevent the water table from dropping
especially bellow 1538 meters. In addition, the construction of an underground dam at the western part
of the aquifer can effectively prevent saltwater intrusion from the lake. In addition, the thickness of the
aquifer in the plain was plotted for selected years to observe changes over time. The results indicate that
the aquifer boundary should be reassessed.