Fig. 1: Temporal trend of annual mean groundwater recharge (mm/yr) in Iran (dark color line with circle marker) and in each of the 30 basins from 2002 to 2017.

This figure shows a statistically significant decrease in nationwide groundwater recharge of about 35% (p value ≤ 0.001) during the study period. The annual change in groundwater recharge varies from –10.3 mm/yr in the Great Karoon basin to +1.9 mm/yr in the Anzali basin, averaging about –3.8 mm/yr across the country. Hd (light brown color dash line with square marker): Hirmand basin, SB (light gray color dash line with square marker): South Baluchestan basin, LD (blue color dash line with square marker): Lut Desert basin, HM (red color dash line with square marker): Hamun Mashkil basin, Pn (green color dash line with square marker): Patargan basin, Ak (light gray color dash line with diamond marker): Atrak basin, SkD (light brown color dash line with diamond marker): Siahkooh Desert basin, CD (blue color dash line with square marker): Central Desert basin, Sn (red color dash line with diamond marker): Sirjan basin, As (green color dash line with diamond marker): Aras basin, SgD (blue color dash line with plus marker): Saghand Desert basin, Sj (light gray color dash line with plus marker): Sedij basin, Mn (light brown color dash line with plus marker): Mehran basin, Hh (red color dash line with plus marker): Helleh basin, Hn (green color dash line with plus marker): Hamun basin, Sd (light gray color dash line with cross marker): Sefid-roud basin, LU (blue color dash line with cross marker): Lake Urmia basin, Ji (light brown color dash line with cross marker): Jarrahi basin, Qm (red color dash line with cross marker): Qareghom basin, Kn (green color dash line with cross marker): Karian basin, WBR (light brown color dash line with triangle marker): West Boundary River basin, Ai (light gray color dash line with triangle marker): Anzali basin, Kh (blue color dash line with triangle marker): Karkheh basin, Hz (red color dash line with triangle marker): Haraz basin, Qu (green color dash line with triangle marker): Qaresou basin, Gi (light gray color dash line with circle marker): Gavkhouni basin, Gn (light brown color dash line with circle marker): Gorgan basin, SL (blue color dash line with circle marker): Salt Lake basin, Bn (red color dash line with circle marker): Bakhtegan basin, and GK (green color dash line with circle marker): Great Karoon basin.