Board Of Directors
INDUSTRY JOURNAL Vol . 8
Board Of Directors
Centre for Environmental Management , University of the Free State
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Over the last decade , we have witnessed some unusual environmental processes playing out in our daily lives . One of the highest-profile events has been the anomaly of flooding in major rivers and dams , while adjacent cities face water shortages . Another of these is the concept of the green drought .
These are anomalies that seem to defy logic , until we examine the processes in greater detail . Today we will be focusing on the notion of a green drought . This is a condition when rainfall coexists with sub-optimal growth conditions for plants and other living organisms . In a green drought it looks as if there is enough water – maybe even an abundance – but there is also clear evidence of water-induced stress in the system . Let us unpack this to gain a deeper understanding of how it works .
As a point of departure , the reader needs to understand that all water begins as precipitation – as either dew , fog , rain or ice . This is when water changes state from either vapour or solid to liquid form . This results in a volume of water being released at a given moment in time . Two things happen at this moment of release , because it is about how much water is present , and the period of time over which the release of water is taking place . The two dimensions are therefore volume and time . How much is there , and for how long is it there ? Most people think only of the first part by focusing on the volume , ignoring the second part , which is about the duration of availability .
Why is the duration of availability important ?
Simply put , a unit of water that is released suddenly is of less value than a unit of water that is released slowly , and for very good reasons . Water released suddenly can be called a flood , which moves with high energy across the landscape . It is that high energy that causes damage to the built environment , and erosion in farmers ’ fields . Water released slowly has lower energy in it , so instead of flowing across the surface of the landscape , it
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