Key science findings

  1. Identification of drought events across Great Britain using simulated river flow and soil moisture
  2. National analysis of future drought risk using MaRIUS baseline and future drought event-sets
  3. Enhanced modelling capability to include surface and groundwater abstractions and discharges in the Grid-to-Grid (G2G) model

The above findings are explored more below.

Introduction

Part of the hydrological research in MaRIUS is to use national scale hydrological models to provide enhanced scientific understanding and modelling capability for representing drought processes. To achieve this, research has focused upon the analysis of river flows and soil moisture for past and future droughts, and the incorporation of abstraction and discharge data in a gridded national scale hydrological model.

1km x 1km Grid-to-Grid simulated mean monthly river flows for May 1995. Flow output can be produced daily or monthly.

Results above from the G2G model which uses a 1km x 1km grid, showing monthly mean river flows for May 1995. Flow output can be produced daily or monthly.

Research approach

The Centre for Ecology and Hydrology’s (CEH) national gridded hydrological model Grid-to-Grid (G2G) provides 1km x 1km resolution estimates of naturalised river flows across the UK, and while originally developed to simulate and forecast high river flows, has now been assessed during low flow and drought conditions. A national scale model can maintain a national- or regional-scale water-balance, ensuring coherence between neighbouring catchments/regions and allowing assessment of the potential impact of water management scenarios on drought occurrence and severity at the national scale.

Ongoing work is using model estimates of river flows and soil moisture, driven by weather observations, to assess change in drought occurrence, duration and severity. An ensemble of near-and far- future weather outputs from multiple regional climate model simulations will provide the driving data needed to understand how drought occurrence and characteristics might change in the future.

Schematic of the Grid-to-Grid national scale hydrological model.

Schematic above of the Grid-to-Grid national scale hydrological model

 

Identification of drought events across Great Britain using simulated river flow and soil moisture

G2G model estimates of river flows and soil moisture, driven by weather observations, have been used to assess change in drought occurrence, duration and severity throughout the 20th Century.  See Rudd et al.  (2017) National-scale analysis of simulated hydrological droughts (1891-2015)

This work also included a low flow frequency analysis (Kay A.L., Bell V.A., Guillod B.P., Jones R.J., Rudd A.C. (under review). National-scale analysis of low flow frequency: historical trends and potential future changes.)

The maps show Grid-to-Grid model output (1km x 1km) of standardised drought severity (river flow) for 1975, 1976 and 1977. They maps show the most severe drought in each year. The darker the colour the more severe the drought.

The maps show Grid-to-Grid model output (1km x 1km) of standardised drought severity (river flow) for 1975, 1976 and 1977. The maps show the most severe drought in each year. The darker the colour the more severe the drought.

Observed and simulated low flow frequency curves for the Thames at Kingston (station number 39001).

Observed and simulated low flow frequency curves for the Thames at Kingston (station number 39001).

National analysis of future drought risk using MaRIUS baseline and future drought event-sets

An ensemble of near- and far-future weather outputs from multiple RCM simulations has provided the driving data needed to simulate river flows and soil moisture into the future. Ongoing work is investigating how drought occurrence and characteristics might change in the future.

 

Enhanced modelling capability to include surface and groundwater abstractions and discharges (G2G) model

G2G has been enhanced to include the influence of abstractions and discharges on river flows

Daily mean river flow for the Thames at Kingston. Observed river flow (black), G2G simulated naturalised river flow (blue) and G2G simulated river flow accounting for abstractions and discharges (red).

Daily mean river flow for the Thames at Kingston. Observed river flow (black), G2G simulated naturalised river flow (blue) and G2G simulated river flow accounting for abstractions and discharges (red).

Poster presentations

  • Rudd, A.C., Bell, V.A., Kay, A.L., and Davies, H.N. (2016) “Statistics in Weather and Climate”, Royal Statistical Society meeting, Reading, 21st March 2016.
  • Rudd, A.C., Bell, V.A., Kay, A.L., and Davies, H.N. (2016) “National-scale hydrological modelling within MaRIUS: preliminary results on historic drought identification and trend analyses (1912-2011)”, The Historic Droughts Symposium, CEH, Wallingford, 22nd March 2016
  • Rudd, A.C., Bell, V.A., Kay, A.L., and Davies, H.N. (2016) “A long-term national-scale hydrological simulation of river flows across Great Britain”, EGU 2016 (Vienna, 17-22nd April 2016).
  • Rudd, A.C., Bell, V.A., Kay, A.L., and Davies, H.N. (2016) “A national-scale hydrological simulation of low flows and drought across Great Britain”, RMetS NCAS Conf 2016 (Manchester, 6-8 July 2016).

Journal Papers

  • Rudd, A., Bell, VA, Kay, AL, and Davies, HN. (2016) “National-scale modelling of hydrological droughts in Great Britain (1891-2015)” (in review).
  • Kay A.L., Bell V.A., Guillod B.P., Jones R.J., Rudd A.C. (under review). National-scale analysis of low flow frequency: historical trends and potential future changes.
  • Rudd, A.C., Bell, V.A. and Kay, A.L. (2017) National-scale analysis of simulated hydrological droughts (1891-2015). Journal of Hydrology. Vol 550, P368-385, DOI: 10.1016/j.jhydrol.2017.05.018 
  • Rudd, A.C., Kay, A.L. and Bell, V.A. (in prep.) National-scale analysis of future hydrological droughts: potential changes in drought occurrence and characteristics

Research Team

Dr Vicky Bell Dr Vicky Bell Dr Ali Rudd Dr Ali Rudd
Dr Alison Kay Dr Alison Kay

 

Dr Ponnambalam Rameshwaran