The assessment of natural flood management measures through land use scenarios in Tarland catchment Oana Iacob1,4, John S. Rowan1,4, Iain Brown2,4, Chris Ellis3,4 1
Centre for Environmental Change & Human Resilience, University of Dundee 2
The James Hutton Institute, Craigiebuckler, Aberdeen,
3
Royal Botanic Garden Edinburgh Inverleith Row, Edinburgh 4
ClimateXChange, High School Yards, Edinburgh
Introduction
Afforestation options
Results land use scenarios
Climate change is one of the most pressing issues facing both scientific and civil society. Greater variability and more frequent extremes of temperature and precipitation result in increased risk of flooding with corresponding social, economic and environmental impact. An important adaptation strategy is to promote more integrated approaches to catchment management, which combine natural flood management (NFM) measures with more traditional, structurallybased engineering interventions.
Afforestation options with different degree of afforestation—50%, 75%
Results are showing that more reductions could be achieved for scenarios that favour the use of coniferous woodland even for low percentages of afforestation. Location and land use cover being replaced by woodland are responsible for the difference between scenarios that suggest the same level of afforestation (i) World Market and National Enterprise and (ii) Global Sustainability and Local Stewardship.
and full afforestation—were considered to better understand the impact woodland expansion options will have on high flows and low flows in Tarland catchment distinguishing between coniferous and deciduous woodland.
Land use scenario Social, environmental and economic drivers are playing an important role
Methods
in the spatial distribution and the
This analysis was undertaken using WaSiM-ETH fully distributed hydrological model
scale of afforestation. These drivers
operationalized for the Tarland sub-basin of the River Dee, Scotland. Baseline data
were pooled together in developing
(1961-1990) drawn from the Weather Generator (UKCP09) were used for this part
alternative land use scenarios which
of the analysis. The afforestation layouts have been developed using Landsfacts and
are being investigated to quantify
ArcGIS software.
Figure 4. Modelling results for the land use scenarios a) Q5, b) Q95
Conclusions
their effect on runoff generation and flood hydrograph characteristics.
Study area Tarland Burn drains approximately 75 km square of land and enters the River Dee at the village of Aboyne. The Tarland Burn is typical for many agricultural regions of Northeast Scotland, in which the major land uses are arable, plantation forestry, improved and unimproved grassland, heather moorland and mixed broadleaved woodland. Frequent floodings have been reported both in Aboyne and Tarland.
The results are clearly showing that afforestation options could be used to decrease the flood risk in the catchment for the current climate.
Figure 2. Land use scenarios for Tarland cathment (Castellazzi & Brown, 2011
Results afforestation options The results show that woodland expansion options will have a significant impact on the flow generation in the catchment, both on the high flows and on the low flows. The changes are higher for increased levels of afforestation with coniferous woodland.
The effectiveness of afforestation options to reduce the flood risk will depend on tree species, afforestation percentage and woodland cover. Extended afforestation is extremely unlikely in Tarland as it provides important crop and livestock benefits. However by choosing coniferous woodland for afforestation in Tarland, significant reductions of Q5 could be
2013
achieved even for smaller levels of afforestation.
Acknowledgement ClimateXChange, Met Office, SEPA, Ole Roessler (Bern University), Marie Castellazzi (JHI)
2002, ©JHI
Figure 1. Land use map Tarland cathment Figure 3. Modelling results for the afforestation options