FLOODS In the aftermath of Alan identified types of floodwater.
Low Risk flooding caused by monsoon rainfall and water table rises.
Medium Risk flooding caused by local watercourse overflowing from amenity or farmland.
High Risk flooding from watercourse flooding from industrial, mining, or sewage areas.
Interestingly, Alan offered the following information saying that 'every time we have 1cm of rainfall, a tonne of water falls on every 100m2
of sports turf. He
pointed out that for example Evesham Cricket Club had over 3.15m of water on their ground for over 3 weeks, which will have resulted in serious compaction of the ground.
The main effects of flooding, include loss of levels, deposits of sediment, compaction, soil nutrients loss and
availability, crusting, poor infiltration rates, an altering of pH, decreased biological activity, a possible increase in weeds and pathogens and the sward make up and rooting depth. All of which reduce pitch preparation. After flooding he reiterated the importance, prior to renovation, of having the soil analysed, not just for toxins, metals etc. but for pH and nutrient values which can be corrected as part of the renovation.
Apart from the normal reasons, the surface cleaning and
scarification/brushing, are needed after flooding to remove sediment, crusting and dead grasses, this will improve infiltration rates and reduce surface compaction.
Choosing the right equipment for surface cleaning has never been so important. If the ground has toxins etc,
then so will the waste removed from the surface! You may need a specialised waste contractor to remove waste off site. In terms of surface restoration the planing off of the turf surface can remove many of the problems at once, by either Koroing or fraise mowing. It is important to note that not all squares are suitable and there is an increase in costs. To get biological activity back into the square, improve gaseous exchange, relieve compaction, improve root growth and the movement of moisture and nutrients, aeration must be undertaken before any topdressing.
Two things will effect the sward make up after a flood: firstly the loss of grasses from being under water for a long period, usually Poa Annua becomes dominant. Secondly, the effect on growth habit by the lack of pitch preparation, where ryegrasses are allowed to crown.
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