Assessment and delineation of potential groundwater recharge zones in areas prone to saltwater intrusion hazard: a case from Central Iran.

Demarcation of the potential zones for groundwater artificial recharge (GAR) based on the most influential factors is an urgent need for retardation of saltwater intrusion and, thus, sustainability of groundwater resources in the arid zones. This study developed an overlay-index methodology to delineate favorable GAR zones by a linear combination of 11 influential thematic layers in ArcGIS. The proposed methodology was implemented on two coastal aquifer settings Sharif-Abad (SAA) and Qom-Kahak (QKA) aquifers adjacent to Salt Lake, Central Iran. Results indicated that 16.41% of the surface of SAA and 28.58% of QKA were identified as the high potential zone for GAR mainly located in low GW vulnerability parts. Based on the analysis of the area under the receptive operating curve (AUC), the produced GAR map has an accuracy of 0.643, and 0.611 for SAA and QKA aquifers, respectively, which relies on the acceptable limit. Finally, the quantity of water required for GAR to control the intrusion of seawater at the suitable parts of these aquifers was estimated as 25 MCM and 35 MCM, annually. The methodology adopted in this study can serve as a holistic assessment for the detection of SWI in coastal aquifers, and also a comprehensive blueprint for managers to delineate the favorable GAR zones, especially in arid regions.

Application of zeolite improves water and nitrogen use efficiency while increasing essential oil yield and quality of Salvia officinalis under water-deficit stress.

Soil moisture and nitrogen (N) are two of the most important factors affecting the production of medicinal plants. So, the management strategy of these factors is critical and to be identified. In order to study the application of zeolite (Z) (0 and 10 ton ha-1) in S. officinalis culture medium under different irrigation regimes (30 % depletion of available soil water (ASW)) and 60 % depletion of ASW) and N (0, 75 and 150 kg N ha-1) a split-factorial experiment was carried out with three replicates in 2018. The highest fresh and dry weight were achieved at irrigation after 30 % depletion of ASW while using 150 kg N ha-1 and 10 ton Z ha-1. Maximum water use efficiency (WUE) (22.10 g.L-1) was obtained after 60 % depletion of ASW and 150 kg N ha-1 and 10 ton Z ha-1. Besides, the maximum nitrogen use efficiency (NUE) was obtained after 60 % depletion of ASW and 75 kg N ha-1 and 10 ton Z ha-1 (14.25 kg.kg-1N). Maximum essential oil (EO) content (1.06%) and cis-Thujone were obtained from plants subjected to 60 % depletion of ASW and, application of 75 kg N ha-1 and 10 ton Z ha-1. Applying Z with N, in different irrigation regimes did improve soil conditions for achieving higher, WUE and NUE, increased the EO content and yield while decreasing the negative effects from water-deficit stress and has provided a direction towards a stable system.