Spatial Distribution Of Soil Types Research Articles

Use of Soil Maps to Predict the Incidence of Corrosion and the Need for Iron Mains Renewal

ABSTRACTThe requirement for revised asset management plans from water‐supply companies and the need to prioritize the renewal of buried water‐supply pipework has stimulated an interest in the spatial distribution of corrosion risk and intensity. This paper reports how the relationships between soil corrosion and the spatial distribution of soil types, as displayed on soil maps, can be combined to predict the likely incidence of aggressive soils and thereby identify those water mains which are most likely to need early replacement. The concept is illustrated by a project supported by Portsmouth Water plc.

The soils of Aldabra

The soils of Aldabra are of patchy distribution, consisting of pockets of either accumulated organic matter or of biogenic mineral detritus. The soils are shallow (10-20 cm) but locally deeper and more extensive soil covers do occur. Organic covers occur under well established Casuarina stands and mineral soil covers occur on the floors of rock basins or where sands are present. The organic soils originate from leaf litter, with local increments of faecal material and bird remains. The mineral soils are primarily carbonate and are derived mechanically from carbonate rocks, from windblown bioclastic carbonate grains or from terrestrial sediments. Solution residues and phosphatic particles also contribute to these soils. Attempts are made to cross-correlate existing soil information, and several organic and carbonate soil types can be recognized. These are: shallow organic (including litter, pellet and guano varieties); deep organic; calcarenaceous bioclastic soils; brown (silt or silt loam) carbonate soils (including a phosphatic variety) and a widespread organic brown carbonate soil. The soils may be slightly acid but are mostly circumneutral or alkaline; high salinity may occur in coastal locations. Phosphate levels are usually low. Insufficient profile data are available at present to define soil type in any rigorous way and the spatial distribution of soil types is only scantily known.