The River Wey: Water & Carbon

• Location


  The River Wey can be found in the South-East of England, flowing through the counties of West Sussex and Hampshire. The river has two tributaries, one starting in Alton, Hampshire and the other south of Halsmere in West Sussex. These two tributaries converge at Tilford in Surrey. The catchment of the river Wey spans an area of 904km2.
• Relief


  The steep-sided valley accentuates entering Surrey, between vast masses termed the Lower Greensand Group, then down the more easterly valley on both sides. The valley falls from about 230 feet entering Surrey, to 60 feet lower at Tilford and changes from almost v-shaped to a more u-shaped alluvial plain.
• Land Use


  A combination of arable, pasture and meadowlands with the larger urbanised areas comprising towns such as Farnham, Guildford, Woking and Godalming. Upstream of Godalming, the catchment has remained mostly in a rural state with pockets of urbanisation, with a mostly unmodified river channel. However, downstream of Godalming, the catchment is largely more low-lying and slow-flowing, with a wide flood plain becoming extremely urban. Parts of the river channel in this area have been modified for ease of navigation.
• River Regime, 2013-2014


  Between 2013 and 2014 there is a very large spike in the flow spanning from late December to mid-March, which almost continuously borders on the highest flow recorded. This could be because, in mid-December, the flow rate is very low. Also. the spike in mid-late-July also appears in between 2015 and 2016, but is nowhere near the levels seen between 2013 and 2014.
• Factors affecting the River Regime, 2013-2014


  Between 2013 and 2014, there were heavy amounts of rainfall (compared to previous years). In fact, it was more than 250% higher than the average in the past years. This large amount of rainfall is a contributing factor to the high flow rate throughout the year.
• Changes to Water Balance & Drainage Basin Stores, 2013-2014


  1. Higher amounts of rainfall

  2. Storms with high-speed winds

  3. Increased flow rate of river

  4. Increased erosion rate of drainage basins

  5. Drainage basins becoming shallower

  6. More water entering the system than leaving

  7. Ground becoming more saturated

  8. Soils unable to hold any more water

  9. Increased risk of flooding

  10. Water stored as surface storage

  11. Water flowing over the land
• Characteristics of the area increasing flood risk


  • Industrialised
  • Covered by concrete
  • Concrete is impermeable
  • Water unable to infiltrate through
  • Water sits on top as surface storage
  • Water has nowhere to go if it floods
  • Increased likelihood of water finding its way into buildings
  • Major disruption on the roads
  • Area is flat and low-lying
  • Water forced to stay above ground as surface storage in puddles
  • Water unable to flow away downhill
• Impacts of winter floods, 2013-2014


  80 homes in a riverside community in Weybridge were submerged under half a metre deep water. Douglas Smith, a 73-year-old lung cancer survivor, has been left without any of his inhalers or medicine. His wife Mavis, strapped on a life vest and ‘floated’ off to try and retrieve some of the supplies left submerged by the floods. Upstream at Byfleet, police closed roads, leading to heavy traffic as drivers trying to enter the A245 were forced to turn back. The floods also caused damage to infrastructure such as power cuts to local residents.
• Flood management strategies along the River Wey


  In response to the floods, many flood management plans were developed. They are focused on the areas that have the highest risk of flooding, such as places near the River Wey’s flood plain. Hard engineering strategies such as physical barriers were put in place. As part of the Wetspots Capital Programme, SCC is constructing a new drainage system on Woodbridge Road in Guildford
• Water Abstraction in the River Wey

  • 220+ water abstraction licenses
  • 340ml can be abstracted per day
  • Used for public water supply
• Thames Water Abstraction in the River Wey

  • 30ml can be abstracted per day at Shalford
  • Abstracted at Shalford from the River Wey or River Tillingbourne.
  • Remaining water abstracted from groundwater in Chalk or Greensand aquifers.
• Future challenges in Sustainability


  The Guildford zone’s groundwater sources are resilient throughout droughts, therefore their deployable output would remain constant under the conditions seen during the recorded time. The analysis findings for the Wey watershed show that the predicted drought scenario would be extremely severe but with a 0.002 per cent chance of occurrence. As such, this shows that the Shalford source has a high resistance to droughts in its current climate.