首页|Soil compaction, runoff and erosion on reclaimed coal-lands (UK)
Soil compaction, runoff and erosion on reclaimed coal-lands (UK)
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NSTL
Many of Britain's reclaimed coal-lands aredamaged by erosion. Much accelerated runoff and erosion iscaused by soil compaction that reduces the land's capacity ofabsorb rainwater. This study compares conditions in tow types ofcoal-spoil, deep-mine colliery discard and surface-coal-mineoverburden, and in four contexts: freshly laid spoil, oldunvegetated minespoil, minespoil partly veneered by grass tufts,and 'reclaimed' spoils, which are defended by a dense grass turfand (ca. 100 mm) deep artificial topsoil. Bulk density testingreveals a characteristic pattern. The soil is of moderate density (<1.3 g/cm~3) in the grass root zone. However, soil densities riseto 1.8g/cm~3 and more between 30 and 50-cm depth Particle sizeand stability tests confirm that minespoils contain a largeproportion of water unstable primary particles, mainly mudstonesand shales. These break down on wetting, flood the soil with fineparticles, and help raise the soil density to levels where waterinfiltration and root penetration is impeded. Rainfall simulationtests on surface coalmine spoils near Blaenavon, Wales, find thatpoorly vegetated plots (50-90 percent cover) convert less rainfallto runoff and yield a fourth as much sediment as unvegetatedplots. Tests of deep coalmine spoils at the Earth CentreReclamation Project, Doncaster, England, found that newly laid,unvegetated, recently washed and hence stabilised, coal spoilsconverted only 20 percent of rainfall to runoff. Older compacted,spoils converted 25-35 percent of the rainfall to runoff whenunvegetated but less than 10 percent A when mantled by thingrass turf Soil losses for the same rain event were more than fourtimes greater on the unvegetated sites. Finally, on both sites, plotsmantled with a deep well-managed layer of applied topsoil sitesabsorbed most of the rainwater applied in tests. This wassubsequently detected running in macropores and fissures belowthe applied topsoil and in the upper layers of the relativelyimpermeable mine-spoil subsoil.
Soil compactionrainfall simulationrunoffsoil lossreclaimed coal landsS. Wales (Pwll Du)N. England (Doncaster).
M.J.Haigh
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1999
International journal of surface mining, reclamation and environment
NSTL
