Dredging/land drainage is it a solution or the problem?
As were are all aware these days of the huge problem of flooding along our river basins. We search for an answer to this huge problem and we hear of many different solutions to it. One of the solutions that is on many a lip is that of dredging/drainage of the rivers.
Is this the answer?
In the last century the OPW carried out a major arterial drainage programme. They dredged many of our finest rivers during this programme. Back then there wasn’t many if any housing or commercial developments carried out on the flood plains of our rivers. The object of this programme was not to prevent the flooding of homes and business properties, no it was to increase the use of the land along the banks of our rivers. They wanted to gain more free draining land for agricultural use. Free and fast draining land was gained but at what cost? Our once beautiful rivers were decimated by this dreadful programme.
They dug drainage channels through this land, land that was once the natural flood plains of the rivers. They dredged the river beds leaving them devoid of all life. The lands were then set out for agricultural use. Along then came the spreading of slurry on these lands. This slurry spreading practice has been carried out year after year on these same lands. The constant spreading of this slurry leads to these lands being over saturated with this slurry and this in turn leads to rainfall not being soaked up naturally. This in turn leads to the rainfall running of the land quickly into these drainage channels and from there straight into the rivers.
Yes, we have increased the speed at which rainfall reaches out rivers.
Now we must look at the decimation of our midland peat bogs. Bord na Mona have absolutely destroyed most of our raised peat bogs. These peat bogs most of which are located in the midlands along the banks of the river Shannon. These peat bogs use to soak up the rainfall and then released it slowly into our watercourses and rivers. Thousands of Hectares of these peat bogs are now lost forever all that is now left is a vast waste land of marl and stone. These vast waste lands offer no soaking up of rainfall, they only add to the speed of which rain water reaches and increases the level of water in our rivers.
Now add to this the over grazing of our uplands. Overgrazing these lands leaves them exposed and devoid of the natural vegetation that soaks up a lot of rainfall. This coupled with the burning of our uplands also leads to rainfall quickly running off the lands and into the watercourses and on then quickly into our rivers. This also adds to the speed of which our rivers fill up and overflow.
Now add in to the mix the increased amount of land which is now in use as forestry. These same lands are planted mostly with non native fast growing species. The planting of these new forests are such that they are set out with drainage channels. This also adds to the fast rate of which rain water runs away from these forests and on into our watercourses and then on into our rivers.
We now must take into account the large scale of developments that was carried out during the “Tiger Years” A lot of these developments took place on the natural flood plains and water meadows along our rivers. The same flood plains and water meadows which flooded frequently during our winters. Developers also culverted natural watercourses and land drains leading to the restriction of natural flow of them.
Now for the big ones! Climate Change, Global Warming and Rising Sea Levels.
Rising Sea Levels will mean that the tides will reach higher up our rivers further increasing the risk of flooding. We all see the effects of Climate change and Global warming has on our weather and on seasonal change. Our winters are becoming warmer and much more wetter.
The problem with the flooding we now have has been a long time in the making, unfortunately it is now here to stay. Is there a long term solution to this flooding?
To what extent would the rivers be dredged? Would the be dredged from source to sea? Would dredging our rivers offer a long term solution?
Many questions which need answering!
Will all this flooding of our rivers have a major effect on the rivers as fisheries? I think no, no not as much as the effect of dredging would have on them.