Spatial Variability of Playa Surface Types in Relation to Groundwater Depth and Salinity Regime: A Case Study from Haj Aligholi Playa, Damghan, Iran.

Document Type : Research Paper

Author

International Desert Research Center (IDRC), University of Tehran, Karaj, Alborz, Iran.

Abstract

This study investigates the influence of salinity regime and groundwater conditions on surface morphology in the southern part of Haj Aligholi playa, Damghan, Iran. A multi-method approach integrating topographic and geological mapping, satellite image interpretation, and field investigations—including soil profile excavation and physicochemical analysis—was employed. Results reveal a systematic spatial transition in playa surfaces from the outer margins toward the center, with five distinct landform types identified: clay floor, soft puffy surfaces, plowed-like clay surfaces (Zardeh), wet zones, and patterned salt-clay surfaces. Groundwater depth decreased progressively from 400 cm in peripheral clay flats to 45 cm in the central wet zone, accompanied by substantial increases in electrical conductivity (EC: 4.6 to 174.8 ds/m) and sodium adsorption ratio (SAR: 5.3 to 191.7 meq/L). These findings demonstrate that surface morphology is primarily controlled by the interaction between groundwater depth (and associated capillary rise) and sediment texture, which jointly determine salt accumulation patterns. The study highlights playa surfaces as sensitive indicators of hydrological conditions and provides a framework for environmental monitoring and land management in arid closed-basin systems.

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