9. Flow and Form - Exercise
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This presentation was given as part of the EPA-funded Catchment Science and Management Course focusing on Integrated Catchment Management, held in June 2015. This course was delivered by RPS Consultants. If you have any queries or comments, or wish to use the material in this presentation, please contact catchments@epa.ie It is increasingly being recognised internationally that integrated catchment management (ICM) is a useful organising framework for tackling the ongoing challenge of balancing sustainable use and development of our natural resource, against achieving environmental goals. The basic principles of ICM (Williams, 2012) are to: • Take a holistic and integrated approach to the management of land, biodiversity, water and community resources at the water catchment scale; • Involve communities in planning and managing their landscapes; and • Find a balance between resource use and resource conservation ICM is now well established in Australia, New Zealand, and the United States. In Europe the ICM approach has been proposed as being required to achieve effective water and catchment management, and is the approach being promoted by DEFRA for the UK, where it is called the “Catchment Based Approach” (CaBA). The principles and methodologies behind ICM sit well within the context of the Water Framework Directive with its aims and objectives for good water quality, sustainable development and public participation in water resource management. In Ireland it is proposed that the ICM approach will underlie the work and philosophy in developing and implementing future River Basin Management Plans.
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9. Flow and Form - Exercise
- 1. 1 Build Partnership Create an ICM Vision Characterise the Catchment Undertake further characterisation Identify & Evaluate Possible Management Strategies Design an Implementation Programme Implement the River Basin Management Plan Measure Progress and Make Adjustments Day 2 – Morning Session ICM STEP 3: CHARACTERISE THE CATCHMENT – Flow and Form - Exercise Example Catchment in County Donegal. 1. Review the BFIsoil Map for the Catchment and comment on the contribution of overland flow to the
- 2. 2 Build Partnership Create an ICM Vision Characterise the Catchment Undertake further characterisation Identify & Evaluate Possible Management Strategies Design an Implementation Programme Implement the River Basin Management Plan Measure Progress and Make Adjustments hydrograph and what this means in terms of the catchment’s response to rainfall and susceptibility to sediment runoff. These are low BFIsoil values in a national context. The lowest are in the upper reaches of the catchment, between 0.27 and 0.38. This means that a low proportion of the hydrograph comes from groundwater flow – that is, a high proportion comes from surface run off. Therefore, the hydrological response to rainfall is flashy with higher peaks steep rising and falling limbs. Soil erosion and transport of sediment to receiving watercourses is exacerbated in such catchments when land use pressures such as overgrazing, peat cutting or forest cultivation expose soils and increase the drainage density. There are some higher BFIsoil values in lower lying rivers that feed Lough Fern. Groundwater contributions are higher in this sub catchment. Therefore peak flows are lower with a slower response, smoother hydrograph. A catchment walkover has been conducted with photographs taken at various locations – shown below
- 3. 3 Build Partnership Create an ICM Vision Characterise the Catchment Undertake further characterisation Identify & Evaluate Possible Management Strategies Design an Implementation Programme Implement the River Basin Management Plan Measure Progress and Make Adjustments Two Upper Catchment Sites, A and B are shown below: 2. What channel form features would you expect to see in the Upper Catchment? • High gradient streams with high transport capacity • Fast turbulent flow • Flat sheets of bedrock or large boulders and cobbles • May feature waterfalls and plunge pools • Banks formed from bedrock or large boulders –erosion resistant except from very high discharges • Mosses, lichens, algae
- 4. 4 Build Partnership Create an ICM Vision Characterise the Catchment Undertake further characterisation Identify & Evaluate Possible Management Strategies Design an Implementation Programme Implement the River Basin Management Plan Measure Progress and Make Adjustments SITE A SITE B
- 5. 5 Build Partnership Create an ICM Vision Characterise the Catchment Undertake further characterisation Identify & Evaluate Possible Management Strategies Design an Implementation Programme Implement the River Basin Management Plan Measure Progress and Make Adjustments 3. Are the site photos for Site A as expected? Yes, banks formed from bedrock and large boulders. Steep narrow channels. Fast flowing. Vegetation cover in catchment. 4. Are the site photos for Site B as expected? No 5. If not, what impacts do you observe? _____________________________________________________________________________________ High content of sediment in watercourse, evidence of excessive flows – fence damage, bank undercutting and erosion – possible because of increased drainage density and soil exposure in catchment. 6. What pressures may be acting that warrant further investigation? • Forestry – cultivation or felling may have exposed soil and created additional flow paths to the stream • Exposed banks in the photo may be trampled • Overgrazing may be taking place upstream • Dumping of fill materials / rubbish near the watercourse
- 6. 6 Build Partnership Create an ICM Vision Characterise the Catchment Undertake further characterisation Identify & Evaluate Possible Management Strategies Design an Implementation Programme Implement the River Basin Management Plan Measure Progress and Make Adjustments 1. What channel form features would you expect to see in the mid Catchment? • Moderate gradient • Substrate of mostly pebble and gravels with patches of sand • Flow types made up of riffle sections interspersed with pools and glides • Some Bank stability but dependent on erodibility of bank material and vegetation cover • Some macrophytes at channel margins
- 7. 7 Build Partnership Create an ICM Vision Characterise the Catchment Undertake further characterisation Identify & Evaluate Possible Management Strategies Design an Implementation Programme Implement the River Basin Management Plan Measure Progress and Make Adjustments SITE C 2. Are the site photos for Site C as expected? No 3. If not, what impacts do you observe? Uniform flow, no evidence of pools / riffles Substrate not visible but discolouration suggests high sediment content and possible pollution source Deep channel in relation to its banks Pipe culvert in channel Exposed banks at higher level Possible excessive sediment accumulation However left bank appears to be fenced off with some sort of buffer zone. 4. What pressures may be acting that warrant further investigation? Discoloured water may be from industry source pollution upstream Deepened channel suggests past channelization for land drainage Trampled banks – cattle poaching Culvert to facilitate channel crossing – source of pollution from farm vehicles, cattle crossing Culvert could also hinder upstream migration
- 8. 8 Build Partnership Create an ICM Vision Characterise the Catchment Undertake further characterisation Identify & Evaluate Possible Management Strategies Design an Implementation Programme Implement the River Basin Management Plan Measure Progress and Make Adjustments A Lowland Meandering Site D is shown below: 1. What channel form features would you expect to see in the lower Catchment? • Low to no gradient • Smooth Flow • Low velocities • Fine Substrates • Macrophytes • Stable banks • Mid channel islands
- 9. 9 Build Partnership Create an ICM Vision Characterise the Catchment Undertake further characterisation Identify & Evaluate Possible Management Strategies Design an Implementation Programme Implement the River Basin Management Plan Measure Progress and Make Adjustments
- 10. 10 Build Partnership Create an ICM Vision Characterise the Catchment Undertake further characterisation Identify & Evaluate Possible Management Strategies Design an Implementation Programme Implement the River Basin Management Plan Measure Progress and Make Adjustments 2. Are the site photos for Site D as expected? • Channel is connected to its floodplain • Evidence of mid channel islands • Channel deposition • But there are impacts observed also.. 3. If not, what impacts do you observe? • Unstable banks • Lack of riparian zone • Bare trampled banks 4. What pressures may be acting that warrant further investigation? Land drainage - Photo of drainage ditch indicates that increased sediment could be getting to main channel Cattle poaching Possible increased sediment load transported from upstream