Scotland River Temperature Monitoring Network (SRTMN) – Riparian Woodland Prioritisation Scores

What is it: 

Increasing river temperatures are a threat to many of Scotland's freshwater species which are often adapted to live in cool environments. This includes ecologically and economically important freshwater fish species such as Atlantic salmon and brown trout. Management of riparian woodland is proven to protect cold water habitats. However, Scotland has ca. 108,000 km of rivers, of which only ca. 35% are protected by any substantial tree cover. Furthermore, the creation of new riparian woodland can be costly and logistically challenging compared to other forms of large scale woodland creation. It is therefore important that riparian tree planting is prioritised to areas where it can have greatest benefits for river temperature, specifically, where rivers are (1) hottest , (2) most sensitive to climate change, and (3) can be effectively cooled by riparian woodland. These three individual criteria can be combined with an equal weight to provide a single riparian woodland prioritisation score that looks to maximise the benefits of riparian tree planting for protecting Scotland’s rivers from the adverse effects of climate change.

Given the variety of potential tree planting options (southerly banks, northerly banks, both banks) and the need to scale results both nationally and locally, the outputs are illustrated as six layers on Marine Scotland Maps NMPi:

  1. Nationally scaled tree planting prioritisation score where trees are planted on both banks
  2. Nationally scaled tree planting prioritisation score where trees are planted on only the most southerly bank
  3. Nationally scaled tree planting prioritisation score where trees are planted on only the most northerly bank
  4. Locally scaled tree planting prioritisation score where trees are planted on both banks
  5. Locally scaled tree planting prioritisation score where trees are planted on only the southerly bank
  6. Locally scaled tree planting prioritisation score where trees are planted on only the northerly bank

Riparian woodland prioritisation scores are on a scale of 1- 20, where 1 is low priority (low temperature, weak sensitivity to climate change and only a small reduction in temperature gained from planting trees) and 20 is high priority (high temperature, strong sensitivity to climate and a large expected reduction in temperature where trees are planted).

Details of the modelling work that produced these layers can be found in two associated peer-reviewed publications (see More Information below). Model outputs are presented on river line features derived from a Digital Rivers Network licensed from the Centre for Ecology and Hydrology (CEH).

Links to Scotland's Marine Atlas: 
Chapter 6: Climate Change
Data originators: 
Scottish Government (Marine Directorate)
This information page is part of the theme: 
Climate Change
National riparian woodland prioritisation scores assuming trees are planted on both banks.
More Information: 

The daily maximum river temperature model for Scotland is a spatio-temporal statistical model that allows current and future river temperatures and sensitivity to climate change to be predicted from; the day of the year (DoY), air temperature on that day, location in the country (region/hydrometric area), location on the river network and the characteristics of the river (elevation, bankside woodland and channel orientation).

Details of the modelling that produced the river temperature and climate sensitivity predictions can be found in: Jackson, F.L., Fryer, R.J., Hannah, D.M., Millar, C.P., and Malcolm, I.A. (2018) ‘A spatio-temporal statistical model of maximum daily river temperatures to inform the management of Scotland's Atlantic salmon rivers under climate change.’ Science of The Total Environment., 612, 1543-1558. (see link under ‘Additional Information’ Tab).

The riparian tree planting prioritisation model is a simplified process-based (deterministic) river temperature model, driven by energy gains from solar radiation, modified by coarse scale characterisation of hydrological and hydraulic conditions. Solar radiation receipt is predicted depending on channel width, orientation, aspect, gradient, tree height, tree location and solar geometry.  Subsequent effects on river temperature are strongly influenced by water volume and residence time which can be broadly characterised by river order. The model compares predicted river temperatures with and without trees (ignoring energy losses) to provide a prioritisation metric, where high values indicate that tree planting can have a large effect on river temperature. The resulting output is a planting prioritisation metric that can be mapped at large spatial scales using information obtained from a digital river network to facilitate management decisions.

Details of the modelling that identifies where riparian trees can have the greatest effect in reducing summer maximum river temperatures and planting prioritisation predictions can be found in: Jackson, F.L., Hannah, D.M., Ouellet, V. and Malcolm, I.A. (2021) 'A deterministic river temperature model to prioritise management of riparian woodlands to reduce summer maximum river temperatures' (see link under ‘Additional Information’ Tab).

To visualise the three bank scenarios it was necessary to produce a total of 3 spatial layers at each spatial scale (i.e. planting both banks, planting on southerly bank, planting on northerly bank). However, the scores are consistent between these layers. To support decision making at different spatial scales, layers were produced to identify priorities at a national scale and then re-scaled at a hydrometric area (regional) scale to highlight local priority areas..

SRTMN national riparian woodland prioritisation scores were produced by normalising maximum temperature, climate sensitivity and planting prioritisation values between 1 and 20, summing scores across the three values and dividing by three, to give an overall prioritisation where each individual component was equally weighted.

SRTMN local riparian woodland prioritisation scores were produced by rescaling prioritisation values within hydrometric areas. These scores reflect local priorities but cannot be compared between hydrometric areas.

Very small rivers (Strahler first order rivers on the CEH digital river network) were removed from this dataset. NAs exist where we are unable to make predictions of maximum temperature, climate sensitivity or planting potential e.g. locations in lochs or in circumstances where we cannot generate the required predictor variables.

This page was last modified on : 
Wednesday, October 6, 2021 - 18:02

Links and Resources

Map Type Click title for metadata and licence informationsort descending Date of data View Map
Map Layers (NMPi) SRTMN - Locally scaled tree planting prioritisation score where trees are planted on both banks 2020-10-27 Access this map on NMPi
Map Layers (NMPi) SRTMN - Locally scaled tree planting prioritisation score where trees are planted on only the northerly bank 2020-10-27 Access this map on NMPi
Map Layers (NMPi) SRTMN - Locally scaled tree planting prioritisation score where trees are planted on only the southerly bank 2020-10-27 Access this map on NMPi
Map Layers (NMPi) SRTMN - Nationally scaled tree planting prioritisation score where trees are planted on both banks 2020-10-27 Access this map on NMPi
Map Layers (NMPi) SRTMN - Nationally scaled tree planting prioritisation score where trees are planted on only the most northerly bank 2020-10-27 Access this map on NMPi
Map Layers (NMPi) SRTMN - Nationally scaled tree planting prioritisation score where trees are planted on only the most southerly bank 2020-10-27 Access this map on NMPi
Type Title External link
Documents A deterministic river temperature model to prioritise management of riparian woodlands to reduce summer maximum river temperatures doi.org
Documents Where should we plant trees? Marine Scotland Topic Sheet www.gov.scot
Documents A spatio-temporal statistical model of maximum daily river temperatures to inform the management of Scotland's Atlantic salmon rivers under climate change. Jackson et al (2018) www.sciencedirect.com
Web link Scotland River Temperature Monitoring Network (SRTMN) www.gov.scot