Subsurface properties of river deposits

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The rivers of Britain are governed by the Environment Agency under the Water frame work Directive. This directive essentially maintains the water quality and ensures the posterity of marine life. The Water Framework looks at rivers biology and river properties like phosphorus and pH. The research described below considers the efforts on river biology from such elements. The chemical quality and organic pollution of rivers in England was recorded at 79% clean, in 2008, the best in England on record and is regarded as an excellent quality. A useful outcome from this study would be if that percentage was potentially bettered though an improved understanding of subsurface properties of river deposits.

( the 79% quote

The environment under the water surface is complex and extremely sensitive to the smallest changes in the waters properties. River beds absorb and release chemicals constantly; this simultaneously cleans rivers of harmful pollutants and the release of oxygen and nutrients provides plants and marine ecosystem with the elements vital for life. The relationship between the bed type and the amount of fluvial action is critical to sustainable posterity of the aquatic environment. The hyporheic exchange that occurs in riverine ecosystems has a symbiotic connection with the river bed. The porosity of the bed allows down welling of water and the nutrients within it. The water oxygenates the bed supporting the life, this life sponges the chemicals and then the water passes back to the river. If any of these properties becomes overwhelmed or exhausted then the ecosystem will die. The complexity of nature is easily spoilt by the ignorance of man and this is the very purpose of the water frame work, to prevent the harmful effects of pollution.

Pollution can on occasion be created by nature, and a section of the river bed ecosystem will be sacrificed to save the river. This is a case of thinking about the bigger picture and the greater good. Unfortunately rivers cannot process the effluent levels of pollution that man produces and this is when whole rivers suffer, this is why the Environment Agency under the Water framework Directive (WFD), has been established. The WFD is a nationwide plan that asses the water quality in rivers, estuaries, coasts and aquifers. The environmental objective is to achieve a national state of “good” or “high” water quality (please see diagram attached) within a specified time period. England has been divided in to several areas based on river basins; each will be gauged independently for its status, aiming to restore them to a near natural state. Some water courses cannot be resorted to a natural sate due to current worth, eg. Power generation or drinking water. good high quote

The WFD was created in December 2000 and became law in December 2003. This recent change come about to create a more sophisticated service and replaced the old General Quality Assessment (GQA). The GQA looked at three separate areas of water quality, in terms of chemistry, biology and nutrients. This guide looked at major sources of pollutants, such as discharges from sewage treatment works or other industries. The aim was to clean up the waste and in the hope that as a direct result the water course would improve. For twenty years this system has worked well and water quality has improved significantly, The biological quality of water courses in England is up 17% since 1990(EA website). As the European Union aims to improve water course's across Europe the WFD is has been adopted to look more closely at England's estuaries, coastal waters, groundwater, lakes as well as rivers. The WTD aims to improve water bodies for the health of the public, animals, plants and habitats. This WTD is in fact in directly working towards the reversal of climate change. Although the initial intention was not to help international pollution, by improving individual rivers, one small step at a time, the Water framework Directive will improve the environment on a global scale. water quality improved quote


This study has the basic main aim to further the understanding of how the subsurface of rivers are affected by hyporheic exchange and any pollutants within the water. After an understanding has been developed, the ultimate aim would be to see is there is any way to reduce the pollution in rivers or to try to use rivers to help climate change, but more locally, the environment around rivers. Through a detailed literature review, a number of questions have come to light that may help to develop this notion.

What affect does human activity have on hyporheic exchange and marine life that inhabits rivers?

Is grain size lineally liked to residence time and how long does pollution need to detrimentally harm the environment?

What impact do humans have on river systems? Can humans affect the system to improve the environment? Or is there any need to; is the natural carbon capture already performing a good job?

To try to answer these questions, this study will see how river beds are developed and how there interact with the flow. The grain size and depth of the armour layer will have some effect on the porosity and residence time. These factors will help to show how real rivers could benefit from the addition of new material in aid of reducing pollution. To develop a fair test several papers have been utilised for there experimental techniques. Below are some points that could be used to study the questions above.

Is there any way to reduce this voiding at the base? Could a permeable mesh or sponge be used to simulate a soft bed material that will not create voids?

As a simple test what if iron plates were used at set levels in the bed? Then the level of corrosion could be used to assess the permeation of the salt based on change in weight and visual inspection.

Temperature and radioactive isotopes are probably of to greater scale for small laboratory tests and therefore adding a non conservative mass to the flume will the best way to study the residence time. Hopefully a coloured tracer can be visually tracked through the bed, this way hyporheic exchange can be timed and a distance can be measured.

These points are explained in full in the literature review.