and landowners at the moment. Many fish species depend on structured habitats for refuge from the current. Finally, there are documented evidences showing clearly that rivers which have been dredged, silt-up more frequently and return to their pre-dredged state. I agree than in practice there are situations where dredging will be necessary, as outlined in your example. It can also hurt fisheries and damage farmlands. Fine sediment loads are likely to increase, as the river is unable to deposit this material on the floodplain. Attenuating peak flow isnt something I touched upon, but I can see how dredging may achieve that. The impacts are generally two-fold firstly as a result of the dredging process itself and secondly as a result of the disposal of the dredged material. Obvious, I suppose when you look at it! Thank you for this informative article Trevor. DK3lUhjP(UZTr3PI LVm ;,&22-iboq F6) In a recent report by the Chartered Institution for Water and Environmental Management, the UK Governments recent proposals for increased dredging activity to take place in order to reduce future flooding impacts have been labelled as a cruel offer of false hope to those living in flood prone communities. It is the Sundarbans and its aquatic environment that face almost certain destruction. I agree that it is certainly important to understand the geomorphology we are dealing with to make sure we understand the whole life costs of managing sediment, but also to understand the mechanisms of flooding, risks and damages within the areas that recieve floodwater. Sustainable revolution is being waged worldwide to reshape our society so that we can reverse the Earth-threatening changes now occurring due to human activities. 0000004918 00000 n Now, even Bangladesh is joining in the sand-dredging craze. I hope I am forgiven for chipping in on this discussions in a field which is not my own! Thought I should find out more and your article really helped. High levels of human activity can result in fewer fish eggs. Bathmetric surveys of the river clearly show that deposition and scour occur to the river bed throughout the navigation to plus or minus 0.5m between each weir reach. Unless of course navigation and magna carta are now outdated. However it is also possible that the reach that was dredged may experience accelerated sediment deposition during low flows, particularly where the dredging activity haswidenedthe channel. The power plant should, therefore, be relocated to an ecologically less sensitive area. Another point to make is that the academic literature has relatively little information on the geomorphic effects of river dredging in low-energy rivers. As someone who enjoys travelling to London most weekends, I certainly wouldnt want to see it underwater! There are a couple of things that might be worth considering though. I agree that overmanagement of upland areas impacts on catchements. W I@Y!Ae)0[400Dq[Xqma:&m1. Thanks for the comment, you raise some interesting points there. In these circumstances you may consider that delaying the onset of peak levels, and advancing the recession through dredging will reduce the duration of overtopping and therefore the volume of water entering the lowland drainage system to be pumped, and with river levels falling more quickly the opportunity to start pumping will presnt itself more quickly. Fill in your details below or click an icon to log in: You are commenting using your WordPress.com account. How a 1980s policy decision caused a permanent problem for Pyongyang. 0000294414 00000 n 12 January 2022. Sustainable might just mean we use geomorphic principles (e.g. However, are you suggesting that just because something needs maintaining it is unsustainable ? River dredging can have a number of impacts on local fish populations. Building a world of resilient communities, Southeast Asias Vanishing Sand Bans are Destroying the Region, How change happens: Lessons from Australias bombshell election, The Local Planet and the Global Empire of Corporations, We feel stronger: Meet those Fighting the Sand Dredging Business in Cambodia, How Indigenous Sea Gardens Produced Massive Amounts of Food for Millennia, Sand Mining Part 2: The Story of a Conflict Mineral, Rapid transition to beat the heat Housing, From regenesis to re-exodus: of George Monbiot, mathematical modernism and the case for agrarian localism, Malaysias fateful choice as land crisis looms, What Could Possibly Go Right? Your idealogical theory to water management certainly isertheoretical. But by its very nature, the act of dredging will change the environment. As a serious point though it is difficult to know whether to engage in an explanation of how the hydrological properties of guttering differ to natural (or even heavily altered) river catchments. Teaser photo credit: By Jubair1985 Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=35363989. Yes dredging is a long term commitment with associated costs but it also very similar to highway maintenance in that it just has to be done.
The two rivers also hold huge, caustic volumes of sulfuric acid, which is exceedingly corrosive to metals, biological tissues even stones.
This makes them more vulnerable to exploitation..
EU members asked to cut down on gas use after new Putin warning, Low lying areas of port city waterlogged after receiving 153mm rain, Messi scores as PSG labour past Japan's Kawasaki, IPL team owners buy SA T20 league franchises, Officially acknowledge Nazrul as National Poet: HC to govt, Five arrested for kidney trade on social media, 1 Covid-19 death, 1,104 new cases reported in 24 hours, PM Hasinas anti-terrorism steps key in ensuring peace in and out of Bangladesh: Assam CM, Netflixs adaptation of Persuasion is disappointing, Sisimpur wins global accolade at International Kidscreen Awards, - , . I agree about the geomorphological response, and it is essential that this is understood for each case to understand consequences and the need for future maintenance interventions. Increased pollution: Dredging churns up old industrial pollutants like PCBs and heavy metals that have settled to the river bottom, adding to the rivers contamination levels. This can be particularly problematic where spoil material is placed either side of the main river channel, creating an embankment. 0000160277 00000 n It promotes riverbank erosion and creates unexpected land losses; flooding can become much more severe as a result. 0000006782 00000 n While it claims that it will stop dredging operations should it become clear that environmental damage is in fact being done, our river eco-systems cannot avoid this kind of devastating damage because by definition to dredge is to damage. After a river is dredged, its banks will become prone to erosion.
To better understand the role of dredging in flood management, the advantages and disadvantages of dredging have previously been assessed by the Environment Agency using six pilot study sites within the UK. If so then we as society may just as well give up on roads, railways, telecommunications, housing, food production, health care etc and return to a pre medievil society. I do feel bad in retrospect for being flippant. Chad O'Carroll has written on North Korea since 2010 and writes between London and Seoul. Neither burning fossil fuels nor river dredging are sustainable in the long-term, and we must seek alternatives. I am very concerned about the simplistic representation of dredging being the solution to everything being peddled by govt. One is precipitated by the dredging process itself; the second is triggered by the disposal of the dredged materials. Since dredging loosens up the soil, these carcinogens will find their way into the water and will cause substantial degradation of the environment. Dredging of upper catchments or steep channels has very different impacts to mid or lower catchment reaches with low gradients and high sediment loads. I was given a tour. Support our mission and help develop the next generation of ecologists by donating to the British Ecological Society. One example of existing unsustainable action being that the EA are currently pursuing the increased conveyance solution, this in turn increases silt and gravel transportation, larger and larger weir structures and greater turbidity of the water all a disaster for wildlife too. 
George Dibdin (Feb 7th).
As with China and India, erosion also disturbs and kills riverbank vegetation, stripping the banks of natural plant cover, which is necessary for shade. And who will be liable for injuries caused by its exportation in the future? For starters, this is a complex topic. In response to UNESCO's concerns over dredging rivers near the Sundarbans in order to facilitate transportation of coal to the Rampal Power Plant, an influential member of the ruling party remarked: "It's not clear to me how rivers will get destroyed if dredging takes place there.". 0000004356 00000 n Thepresence of these dredgers, removing sands, sediment, and shingle from the bottom of the water body, is one of themany things thatset thecity apart. Faster flows are the best way ,so without regular cleaning of debris the system is useless for modern agriculture. Those living on river banks, such as water voles, or those on the floodplains themselves, such as wading birds, can also be affected. Our latest thinking and opinions straight to your inbox! The economic and sustainability issues are key. Dredging is a necessary activity that is required to increase the depth of rivers and remove the unwanted deposits for safe passage of boats and ships. The loss of natural habitat can render new dredged habitats unsuitable for shallow-water fish. The notion is that by removing the amount of sediment within the channel you are able to increase its capacity. The writer is Professor of Physics at Fordham University, New York. You can unsubscribe at any point via the link in the newsletter. It harms biodiversity, affects water turbidity and water table levels. 0000005519 00000 n Thats a valid point. 245, Russian envoy says North Korea could send workers to breakaway Ukrainian states. The only debate will be: who will pay for its repair? BAPA claims these rivers are victims of dangerously toxic industrial discharges, including mercury, lead, chromium, cadmium, arsenic, potassium, calcium, manganese, and many others. If were worried about flooding then whatwe need to do isstop building in the river floodplain, and not only infrastructure. Peat in upland areas is often drained to make the land habitable for sheep and grouse. We know its highly likely were causing global warming, but we havent instantly stopped burning fossil fuels. For example, riverbanks become more susceptible to erosion. Can anyone advise me on these important matters concerning the Somerset dredging ? Draining and burning destroy sphagnum moss which creates the peat in the first place. The overall aim of most dredging activities is to reduce the extent of flooding and act as a flood management tool. (LogOut/ The purpose is to clear river channels for shipping lanes. Effects can be immediate or develop over a longer time frame and they may be temporary or permanent. It might be me misreading the last part, but I thought it worth clarifying that the blog is independent of the EA (or indeed any other body or organisation). We know its highly likely that our river maintenance regimes are detrimental to ecosystem functioning, but we havent instantly stopped dredging. It's a fact that most of the rivers in Bangladesh are contaminated with toxic industrial wastes. All in all, its a lose-lose situation and it calls for a reassessment of the governments approach to clearing channels in the Jamuna River. Eroded banks will stimulate further build-up of silt, exacerbating rather than improving problems with navigation. In the aftermath of the last 12 months flooding I suspect it will be a hot topic. This is especially true for motor boaters who travel at high rates of speed. This may have been plausible before man polluted the world but the only way nature will rule again is if humans dont exist and in the meantime we really need a mechanical interface to maintain a gentle balance between flooding and nature. Endangering water quality: Dredging stirs up silt that kills mussels and other aquatic life and is expensive to remove from drinking water. To illustrate, our data indicates that over 500,000 tons of sediment is transported of which 50,000 tons is deposited each year. Causing hazardous conditions for recreational boaters: Dredging cables that attach the rigs to the banks are often hidden underwater, and are dangerous for recreational river users. This, in turn can, cause even greater silt build-up in the river, making navigation of the rivers channels by ships more, not less, difficult. In our view reintroducing dredging to the Thames in a co-ordinated manner is part of the solution. Other adverse effects of turbidity include decrease in disease resistance, suffocation and death. With all of these potential changes, why do we bother?
Upstream attenuation in these circumstances can only be A drop in the ocean. Consequently, growth of fish and other organisms will be affected since food supply will be reduced in the turbid conditions. If you think about the River Thames and the Thames Barrier that structure is essential to making sure that one of the most important cities in the world doesnt flood. If we assume that a dredging activity increases channel capacity then it can also be assumed there will be a reduction in the frequency of overbank flow events as more water can be stored within the channel. Do you think these would make a tangible difference to reducing flooding? Hi Trevor, This is a really interesting perspective, and as you say towards the beginning of your piece with the aid of your MS paint diagrams, for big events in simple flood plaines the capacity of the flood plain far outwieghs the capacity of the river. The government of Bangladesh could have avoided the controversies surrounding Rampal if the policy makers had shed their anthropocentric view of the environment and, instead, were guided by the principle of "sustainable revolution" in choosing a site for the power plant. What is most important is that technical experts and sustainability commentators truly understand the context of the catchment before leaping in with generalised advice. 203 0 obj <> endobj xref 203 35 0000000016 00000 n Can we justify preserving landscapes forheritage? For river dredging it may be managed retreat and floodplain abandonment. In addition, Microsoft cyber-security chief Chris Jackson has been urging users to stop using the browser since February 2019. Spawning is a stressful period and fish are highly vulnerable to disturbance during this time. In the UK the principal reason for river dredging is flood defence.
0000042419 00000 n Dredging involves the removal of sediment from the bottom and sides of river channels and can also include straightening of channels and deepening of the bottom. There are now over 28000 acres flooded in the Parrett catchment to a depth of 3 m in places.
Some of our systems have been managed in such a way that future maintenance seems inevitable, and I do not believe that maintenace, such as dredging, is unsustainable. The problem is whether the comment is originally meant in an enquiring way, in which case it is appropriate to spend a long time explaining. 0000041974 00000 n Please provide the data illustrating the cost benefit analysis of; In river management there has been a movement away from maintenance and towards restoration, floodplain connectivity and flood storage areas. A few key papers havehighlighted the following morphological effects of dredgingin high-energy rivers: A number of studies have considered environmental/water quality/biodiversity issues, but there hasnt been much focus on lowland systems. 0000042794 00000 n I have enjoyed this.
Ask a North Korean: How do North Koreans stay cool in the summer heat? Professor Quamrul Haidar of Fordham University, New York, who has studied the adverse impact of river dredging in Bangladesh claims there are two main adverse impacts caused by the dredging. So, the effects discussed in this article are generic. Dredging is without doubt a suitable management tool in some circumstances but is equally unsuitable in other circumstances. But so damaging was the dredging that it has been banned. The fact is that we have 21st century flood plains which depend on 21st century river management. Blocking these drains and resaturating peatland would go someway to slowing water flow within catchments and would also restore sphagnum habitat aiding peat formation and carbon sequestration. 0000002976 00000 n
research tools, and unique data sets. An increase in channel slope upstream of the dredging activity, potentially creating a knickpoint, Reduced sediment availability leading to a simplified channel planform in inherently braided systems, Vertical incision leading to river bank instability and potentialchannel widenning, Greater streampower leading to the transport of coarser sediment downstream of the dredging activity, combined with a greater fine sediment load to cause bed armouring, Having done recruitment outside academia I'd say key thing, (alluded to in many replies here) is to be positive abo, This map demonstrates clearly Venice is (at best) only the city with the second most miles of canal though.. However this theory may not work well for embanked high level fluvial carriers where flood water spills into lowland pumped drainage systems. Otherwise, Rampal will be the last straw that broke the camel's back. It doesnt take long for visitors toPyongyang to notice the smallboats dotted alongthe Taedong river, mounted either with cranes orladen with aggregate-filled cargoes. How Sweden created a safe space for North Korea talks NKNews Podcast Ep. Professor Haidar says that the loss of natural habitat can render newly dredged habitats unsuitable for shallow-water fish seeking refuge from river currents. Though the government there is making efforts to regulate sand dredging and police widespread illegal dredging, river dredging is so rampant that the state has almost lost the battle to protect its rivers. (2007)demonstrated in their study of anupland,coarse sediment-dominated river, Gravel has a role to play in providing spawning habitat for fish, Fine sediment is important for species such as lamprey, which provide an ecosystem service in the form of pasture for cattle grazing and improved in-stream water quality. Recent satellite images prove that it is having a widespread and detrimental impact. Since the halt of full time dredging in the 1980s the depth of the fairway ie the navigable part of the river has become narrower but maintained its depth whereas the edges have become much shallower. 0000040263 00000 n
0000003546 00000 n
Internet Explorer is not compatible with this website. Invertebrates and fish can be affected via sediment disturbances and loss of habitat, which can have knock on effects for those higher up the food chain. Theres no question: Bangladeshs river dredging business will damage the Jamuna River. We've got gauging stations in the most amazing of places. So concepts like biodiversity are something we either value as a society or we dont, there is no right answer, but its important to be aware when we implicitly stack the game board against one option.
0000291071 00000 n It seems the community has been crying out for a post of this nature and so here I am;gallantlyriding into themaelstromof a politically sensitive issue, on the back of my watery steed, wielding my lance of science and wearing my armour of academic integrity. In the case of India, not to mention China, its obviously severe. Or email us atdataprotection@britishecologicalsociety.org. This will have grave consequences on freshwater marine life. 0000042344 00000 n Things cannot change over night, but they must change eventually. trailer <<08BF6D151CFB4068A1A338EED1BA8961>]/Prev 1094732>> startxref 0 %%EOF 237 0 obj <>stream Piyali Banergee is a member of Nature Watch, Bangladesh. Dredging will affect a river's composition, diversity and resiliency in a variety of ways. 21st century floodplaines require enlightened 21st century intervention. There is an argument to say that in the long-term, even land that is currently used for arable agriculture will have to adopt a different land-use to accommodate a less predictable climate. 0000006396 00000 n Thus, dredging is an unsustainable activity since it needs to be repeated frequently. What would your solution have been please ? In the past, it has mainly been dredged up from the Yangtze River. Of course dredging never destroys a river. d) review the existing policy preventing riparian owners from maintaining the depth of water by dredging. However, understanding the extent to which dredging can mitigate against flood risk and flooding events can be difficult because of the differences between location and river system hydrology and ecology, which can influence the resulting outcomes. Once peat is dried water runs off it very quickly into streams and rivers. 0000297622 00000 n During the dredging process effects may arise due to the excavation of sediments at the bed, loss of material during transport to the surface, overflow from the dredger while loading and loss of material from the dredger and/or pipelines during transport.
