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UID:pretalx-soil-health-now-2026-WGPZP9@pretalx.earthmonitor.org
DTSTART;TZID=Europe/Athens:20261209T143000
DTEND;TZID=Europe/Athens:20261209T144500
DESCRIPTION:Climate change is projected to increase the intensity and frequ
 ency of extreme rainfall events\, amplifying the risk of surface runoff an
 d associated soil degradation. While relationships between soil organic ma
 tter (SOM)\, bulk density (BD)\, and soil hydraulic properties are well es
 tablished\, their translation into runoff thresholds under realistic storm
  structures remains insufficiently quantified.\nIn this study\, we combine
  national-scale soil observations from the UK Countryside Survey with proc
 ess-based simulations using HYDRUS-1D to quantify how changes in SOM and B
 D influence infiltration capacity and the onset of surface ponding and run
 off under contrasting storm regimes. Vertical water flow was simulated by 
 solving the Richards equation with van Genuchten–Mualem hydraulic parame
 terisation across a range of soil textures\, BD values (1.15–2.00 g cm
 ⁻³)\, and storm scenarios representative of UK rainfall structure (25
 –50 mm over 3–6 h\; cyclonic vs frontal).\nResults demonstrate non-lin
 ear threshold behaviour in runoff generation\, with small increases in BD 
 leading to disproportionately large increases in runoff\, particularly in 
 medium-textured soils. Across simulated conditions\, runoff initiation occ
 urred at lower BD values under short-duration\, high-intensity (cyclonic) 
 storms compared to longer-duration events. Analysis of Countryside Survey 
 data indicates a national-scale shift towards lower BD in cropland soils b
 etween 2007 and 2020\, consistent with modest increases in SOM (~0.003–0
 .005 g g⁻¹)\, which correspond to substantial reductions in simulated r
 unoff under extreme rainfall scenarios.\nThese findings provide a quantita
 tive link between soil structural condition and hydrological response\, hi
 ghlighting critical BD and SOM ranges where management interventions are m
 ost effective. The results emphasise that storm structure\, in addition to
  total rainfall depth\, is a key control on runoff thresholds\, and should
  be explicitly considered in assessments of soil-based natural flood manag
 ement strategies.
DTSTAMP:20260825T193229Z
LOCATION:Amphitheater I
SUMMARY:Linking soil organic matter\, bulk density and runoff thresholds un
 der extreme rainfall: a modelling study using GB national soils data - Mau
 d van Soest
URL:https://pretalx.earthmonitor.org/soil-health-now-2026/talk/WGPZP9/
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