Description: This layer describes the Recovery Potential of a reach, which is a measure of river energy based on specific stream power (W/m2) (see lineage section to understand how SSP is calculated). Rivers with higher energy have a greater capacity to 'self-heal' and can be restored using passive restoration techniques. In contrast, lower energy rivers require more costly interventionist restoration approaches such as remeandering. Through understanding the energy regime of the river we can design restoration to minimize the work needed and maximize the length of river improved by working with and enhancing the natural processes of the river. The dataset was developed in conjunction with the 'Will the river do the work?' (will-the-river-do-the-work.pdf (sepa.org.uk)) SEPA technical report and more information about how it was calculated can be found there.
Copyright Text: Stream power is the key attribute calculated to support this layer. This was derived from the Slope layer (calculated using the 5 m next map DEM) and discharge at QMED (CEH QMED flood dataset calculated for each 50 m point), the channel width derived from channel outline from the 2008 Ordinance Survey maps. As part of the STREAM project the baseline waterbody was separated into reaches with a homogeneous character (similar slopes and channel width). This reaches were used and Specific stream power was averaged for each homogeneous reach to convert the 50 m point data to vector lines of the waterbody. The CEH baseline network was used to map the location of the rivers. The stream power was then used to derive the recovery potential categories. 7235 km of waterbody was walked in Scotland and the reference river type recorded as part of the less than good surveys. Stream power ranges were extracted and mapped for each river type creating the resilient to change, high, moderate and low recovery potential categories.
Description: The RAMI layer is calculated for all baseline river water bodies. Anthropogenic pressures which were believed to degrade channel form were mapped across all these water bodies. This includes bank protection, culverts, river straightening, bed reinforcement, embankments, weirs and more. This mapping was initially done using remote sensing (e.g. aerial photographs and OS maps) to identify the pressures. All baseline rivers that were identified as being at less than good morphological condition, or in good but close to poor morphological condition due to these modifications were then field surveyed, so that the reliability and resolution in the data was improved. This includes > 7,000 km of river that were walked. River type was also recorded, as the type of the river impacts the degree of impact the anthropogenic pressure will have. The river types include: bedrock, cascade, step-pool, plane-riffle, plane bed, active meandering, wandering, passive meandering and peat. For example, a stretch of bank protection on a bedrock river will have less of an impact on river form and habitat than it would have on an active meandering river, which would naturally be able to move sideways across the floodplain. For every pressure and river type combination, impact ratings were created, to predict the impact that pressure was likely to have on a specific type of river. The impact ratings (see MImAS reference at this end of this section) were then used to calculate the degree of impact (or capacity used) for every 1 km stretch of the baseline river network to create the River Anthropogenic Modification Index (RAMI). Capacity used = Impact rating x pressure footprint 1 km length The pressure footprint was simply the length of that pressure within the 1km length being assessed. This was then divided by the length being assessed (in this case 1 km) to get a measure of the capacity used (i.e. how much impact is the system likely to be undergoing). The resulting number was then used to place reaches into categories based on the extent of modification (Table 1). Table 1: Capacity used score as calculated within the RAMI approach and resulting modification categories. Capacity usedRAMI category< 25%Low modification25.1 – 50%Moderate modification50.1 – 75 %High modification75.1 – 100%Significant modification> 100%*Very significant modificationN/AWetland/unknown river type** * Due to overlapping pressures, in some circumstances more than 100% capacity can be used.** Capacities were not calculated for this type of waterbody.Method to produce the RAMI layer in GISAll the information was extracted from the different GIS layers (morph pressures and river type) and converted into tables in Excel format. The different pressures were split into different parts when the pressure expanded two river types. This helps to work out accurately the MImAS capacity (i.e. apply the correct impact rating to each section of the pressure). The way to control the length and location of pressures and river types was made using river codes (from the SEPA river network) and downstream and upstream distances. The excel file used for tuis purpose is this one: The excel file contains different tabs. The tabs that have used for this project are in blue and named starting with a ‘3’. Tab “3 Water metrics”:To create an internal ID (Internal ID before extracting reaches)Column F: to find the location (reach number) of the downstream distance of every pressure. Reach number are 1, 2, 3, …… each of those correspond to e.g.: reach 1 is the first 1000m reach, reach 12 is 12,000m, etc.Column G: to find the location (reach number) of the upstream distance of every pressure. Reach number are 1, 2, 3, …… each of those correspond to e.g.: reach 1 is the first 1000m reach, reach 12 is 12,000m, etc.Column H: to identify if the pressure is contained in the same reach number.Column I: to identify if the pressure expands several reaches. Columns J and K: for the same pressure works out the lowest reach where the pressure expands. It works out the Mimas capacity in K.Columns L and M: if the pressure expands more than one reach, the reach number and the capacity used is worked out here (M). Columns N and O…. same that before.Etc… Tab “3 Water Metrics 1.1”: Insert the internal ID and Rivercode before each pair: JK, LM, NO, etc, to make it easy to create a table with all those reaches. To create a new Tab where I will paste all the columns with all the new reaches. (3 Water metrics 2)Tab 3 Water metrics 2:I copy all the Pairs: RAMI Reach and capacity used for that RAMI reach I copy all seven pairs and paste them in columns one under the other (i.e. I need a table with the same columns showing reach and capacity for the different reaches)When I copy the columns in b, I also copy the unique internal ID produced in 1. This will help to bring all the information from the tab Water Metrics, later on to Water Metrics 2.Also, I need to create two columns with the DWN and UPS distance of reaches 1000, 2000, 3000, etc. to do linear referencing later. Then I will create a dynamic table to Sum the capacity use in each Reach within each RivCod. This capacity value will be the one that will be useful to allocate the RAMI value. (Tab 3 Water metrics Pivot 3).Tab 3 Water metrics Pivot 3: The dynamic table uses data from Water Metrics 2.The table extracted from this dynamic table will be the one to export to GIS using linear referencing. I used a annex tab to help producing this tab (Tab 3 Annex to pivot 4).The final table to be used in GIS is in tab “3 Extract to GIS 6”.GIS work. I used ArcGIS Pro. Linear referencing tools making use of RivCode and downstream and upstream distances for each 1000 reaches. The shapefile was generated. RAMI_test1.zip (this version, attached below, has not metadata yet).
Description: This brief technical note has been prepared for the SEPA Planning Team to share the layer with Councils and apply riparian corridor principles together with potential/existing geomorphic risk for consideration within new developments and Local Development Plans (LDP). This summary aims to describe how to use the layer and present caveats on how not to use it for the purposes of new developments. 1. Main principlesThe scale of the layer is national for the baseline river network, i.e. those river water bodies with catchment area greater than 10 km2.This layer made use of:ST:TREAM reaches (baseline river network). These reaches show homogeneous sections of rivers in terms of slope, channel width and flow, and therefore energy. These reaches were used to model potential erosion, transport and deposition. River typology layer (baseline river network).Morphological pressures (baseline river network).The assessment was carried out to identify zones where we expect significant channel erosion and deposition (i.e. leading to channel mobility and instability).Reaches of river were assessed as low risk of mobility and removed based on: if the river type was unlikely to significantly adjust laterally: passive meandering, bedrock, step-pool and plane bed. where the ST:REAM modelling suggested that the processes were predominantly transport/transfer (I.e. deposition or erosion was less likely). consideration of where specific morphological pressures would impede channel adjustment, e.g., bank protection on both banks, etc. (to be confirmed). The width of the polygons is based on the channel width. Lateral channel adjustment is proportional to channel width which is linked to Qmed. 2. How to use it The layer is a shapefile/geodatabase that can be opened in QGIS and ArcGIS. The symbology of the layer shows the areas in polygons (no lines) where there is potential geomorphic risk, e.g. significant erosion of banks that can impact a road. There are two main uses for land use planning:It is not advisable to develop land next to those polygons due to the increased risk of the channel adjusting within this zone; and,Consideration of the potential risk posed to existing infrastructure adjacent to the polygons and the implications of this for future infrastructure provision and development. In some cases there may be options to mitigate this risk. However, hard engineering techniques are not recommended unless completely necessary and may increase the risk of erosion in adjacent reaches. Consideration of a riparian corridor within these spaces is a far more beneficial approach as it helps to mitigate this adjustment.Note: this is based on data collected before 2017 and models run in 2013. Therefore, the data should be ground-truthed as changes may have occurred. See sections below: Site assessment Please always assess the risk via fluvial audit (i.e. ground truthing) to identify new pressures, changes, etc. to be considered within the development. The data provided is aimed to help identified geomorphic risk, but this is not 100% reliable, and rivers change overtime, so use only most up-to-date field data. River networksThe polygons are originally following the digital river network produced by the Centre for Ecology and Hydrology (CEH) 1:50k. This does not match the OS Mastermap. See example in Figure 1, in these cases please, assume the risk is in the nearest section of your river network (if you are not using CEH 1:50k). Please, do not assume the polygon is on the right place on your map without previously checking your river network against the approximate centre line of the polygon. Figure 1 OS Master Map and CEH do not match. The dark blue line with the green polygon corresponds to CEH 1.50k, see how it runs parallel to the river in OS MM. The geomorphic risk would be then allocated to the equivalent section of the OS MM (extract of the Back Burn in Fife).Approximate buffersThe width of the geomorphic risks buffers is approximate, a site assessment will help to assess size in relation to local constraints and landscape settings. In some cases the actual width to apply could be wider, or narrower in others. The extent shown in the layer is just an initial estimate. Network is not up-to-dateBe aware that the CEH 1.50k digital river network used for the layer is not up-to-date. This means, the rivers planform (shape) may have changed, and therefore the geomorphic risk has changed and new site assessment must be done. See example in Figure 2, the existing channel in the Lyne Burn (Dunfermline, Rex Park) follows a different route now as it has been restored to a sinuous form through the park. Figure 2 The Lyne Burn has a completely different planform through the Rex Park in Dunfermline. The geomorphic risk polygon is picking the previous existing risk based on a much faster straightened channel. Help identify risks in existing infrastructure within the new development of LDP.The layer can help identify risk for future developments but also geomorphic risk for existing infrastructure that may be associated with new developments. Therefore, this risk should be assessed for both what has already been built and the proposed new development. By considering both, it can help mitigate future impacts. See Figure 3, example in the River Nith, where there is geomorphic risk near roads in different locations. Figure 3 See geomorphic risk near potentially impacting different roads (overlapping roads). These sections may require special attention and site visits to confirm if mitigation is required. (River Nith, North of Dumfries). 4 July 2022Roberto Martinez Helen ReidSEPA Senior Hydromorphologist SEPA Senior Hydromorphologist
Service Item Id: d4639908e4e84b3e8c25e6ad4a0cc652
Copyright Text: This layer made use of:
• ST:TREAM reaches (baseline river network). These reaches show homogeneous sections of rivers in terms of slope, channel width and flow, and therefore energy. These reaches were used to model potential erosion, transport and deposition. • River typology layer (baseline river network).
• Morphological pressures (baseline river network).
Description: Aim of this layer:This layer combines the “riparian vegetation quality” layer, with the “energy (will the river do the work?)” layer with the aim of identifying, at a catchment scale, areas where riverbanks could be protected from erosion by improved riparian vegetation ideally including riparian woodland. Thus, the new layer identifies areas where:- tree planting will benefit geomorphology through river restoration when morphological pressures were present in a particular section. Note: existing morphological pressures have not been included in this layer apart from riparian vegetation loss. Further work is currently being undertaken by SEPA to consider other existing morphological pressures. The mapped outputs of this work will be made available in due course and could inform more detailed project stages. - and sections where lack of trees are exacerbating geomorphological process like bank erosion etc. This layer classifies the cells into high, medium, low priority for riparian woodland planting. This layer is for:- Riverwood. Woodland extension tool- Local Development Planning – This layer could be used as a source of evidence at a strategic scale to identify where riparian vegetation, and particularly woodland could be beneficial to the water environment within a catchment. It is noted that site specific assessments would be required to inform individual projects, including with regards flood risk. Method:The layer makes use of the sections where the vegetation condition is poor or moderate for each bank (good condition and other habitats are excluded from the analysis) and sections where the recovery potential of the channel is high. E.g., if there were morphological pressures in that river reach, that section of river has the energy to self-recover of recover with assisted restoration, and riparian planting plays a role on that mitigation. The scoring table is shown below, table adds the priority score for both elements:Tablerows: Vegetation quality (score/priority) Columns: Energy for self-recovery (score/priority) Low (3) Moderate (2) High (1) RTC (1) Poor (1) 4 3 2 2 Moderate (2) 5 4 3 3- High priority for riparian woodland planting (green): final score 2. Raster value 1- Medium priority for riparian woodland planting (blue): final score 3 and 4. Raster value 2- Low priority for riparian woodland planting (amber): final score 5. Raster value 3Caveats:- The layer is useful at local development planning scale to identifying wider areas where tree planting could benefit the water environment. This is not intended to be used at project scale where further assessments would be required. - Some areas may show not up-to-date information for the existing condition of the riparian vegetation. - This layer only considers baseline water bodies (those with catchment greater than 10km2).Raster format 25m
Copyright Text: Riparian vegetation data collated from field surveys undertaken by SEPA Geomorphology Staff and contractors for less than good water bodies, rest based on GIS analysis. Energy data based on will the river do the work. Then both layers have been combined to produce this layer following the method detailed in the description.
Description: The Riparian Corridor GIS layer is a buffer zone that extends from the banks of all natural watercourses in Scotland. The Riparian Corridor buffer has 3 size categories: 10 m 15 m, and 30 m. The size of buffer is determined by the width each watercourse; channels less than 2 m wide having a corridor of 10m, 2 m to 15 m wide, 15 m and greater than 15 m wide, 30 m applied to each bank. In total, the riparian corridor buffer zone adds 20 m, 30 m or 60 m to the width of each river channel.
Service Item Id: d4639908e4e84b3e8c25e6ad4a0cc652
Copyright Text: The mapped network of natural watercourses and their attributed width values were derived from the Ordnance Survey National Geographic Database, Water Link layer.