Design–monitor–remediate: A framework for soil moisture control and monitoring in nature-based soil remediation application

Effective soil remediation requires controlled soil moisture conditions, however the hydraulic consequences of irrigation system design remain poorly quantified in remediation-oriented contexts. This study investigates how subsurface irrigation design parameters control soil moisture distribution and connectivity, and evaluates the capability of time-lapse Electrical Resistivity Tomography (TL-ERT) to monitor these dynamics. Controlled laboratory experiments were performed in a soil-box biopile using five irrigation configurations based on subsurface drip irrigation (SDI) and porous pipe irrigation systems. Flow rate, installation depth, orientation and spatial layout with a constant injected water volume (1.5 L). Pseudo-3D TL-ERT results were validated with independent gravimetric moisture measurements. Moisture distribution patterns were consistently observed across all configurations which reflected the combined influence of pipe type, flow rates, depth and layout. SDI systems produced localized, dome-shaped wetting patterns beneath emitters, whereas porous pipe systems generated broader lateral spreading and, in multi-pipe configurations, hydraulically connected subsurface fronts. Electrical resistivity decreased from 150 to 250 Ω·m to 10-60 Ω·m within wetted regions (up to 60% reduction), corresponding to gravimetric moisture increases from 15% to 20-25% (65-80% of water-holding capacity). Beyond pipes system comparison, this study provides the first integrated quantification of irrigation-design-controlled moisture distribution using validated TL-ERT monitoring and formalizes these findings into a Design-Monitor-Remediate (DMR) framework. The framework links hydraulic design parameters with geophysical indicators to support adaptive optimization of remediation systems where moisture regulation is operationally critical.