Impacts of climate on water-use and water-use efficiency of woodlands in the Sudanese Sahel region: a modelling study

Tutkimustuotos: Artikkeli kirjassa/raportissa/konferenssijulkaisussaKonferenssiartikkeliTieteellinen

Abstrakti

The Sahel belt of Africa has been identified as a “hot spot” of global environmental change. However, the response of this semi-arid region to climate change, particularly in relation to woodland vegetation cover and water-use, remains unclear. Climate change could cause major ecological disruption and conflict in the region. We have modelled the impact of various climate change and emission scenarios on the water-use and water-use efficiency of woodlands across the Sudanese Sahel region for the 2080s.

Modelled monthly mean scenarios of climate variables (temperature, precipitation and cloud cover) for the period 2070-2099 were derived using five GCMs (CGCM2, CISRO2, ECHam4, HadCM3 and PCM) run with A1FI (greatest climate forcing caused by fossil fuel usage) and B1 (least climate forcing caused by fossil fuel usage) SERS emission scenarios. The climate data were generated for nine grids (1.0º latitude x 1.5º longitude), covering 11.5–17.5 ºN by 24–36 °E, were selected so as to cover the current climate conditions of Sudanese Sahel region. Climate data from TYN SC 2.0 dataset were extracted. Baseline (1961-1990) observed monthly mean values of same climate variables were extracted from the CRU TS 2.1 dataset. The climate data were calculated as the average of the resulting six TYN/CRU grids per study grid. A simple water balance model, WATBAL, was parameterized for woodland vegetation and two soil types, arenosols (AR) and vertisols (VR) using HWSD soil data, to give monthly water-use (ETc_adj) values for the baseline data and each climate change scenario dataset. Water-use efficiency (WUE, g C m-2 mm-1) for each study grid was calculated as mean above-ground biomass C density (g C m-2) divided by ETc_adj (mm).

Grid baseline annual rainfall ranged from 5 to 55 mm and temperature from 23.3 to 29.2 °C. Mean annual air temperature increased under all 10 climate change and SERS scenarios and for all nine grids (+1.2 to +8.3 °C), while rainfall either increased (+1 to +30 mm) or decreased (-1 to -16 mm), depending on scenario and study grid. Grid baseline ETc_adj varied from 56 to 595 mm and WUE from 0.106 to 0.462 g C m-2 mm-1, depending on grid and soil type. Compared to AR soils, VR soils had equal or greater water-use and equal or less WUE. Depending on climate change scenario and grid, the relative water-use (scenario/baseline) of woodlands varied from 0.54 to 6.79 for VR soils and from 0.61 to 4.33 for AR soils while that of WUE varied from 0.50 to 2.44 for VR soils and from 0.46 to 2.22 for AR soils. The largest relative changes in water-use were associated with the drier grids. WUE decreased for the drier grids, but either decreased or increased for the wetter grids, depending on SRES.

Our results indicate that the water-use in the Sahel region will strongly depend on the degree and nature of climate change and adaptation of woodlands.
Alkuperäiskielienglanti
OtsikkoInternational Climate Change Adaptation Conference: Climate Adaptation Futures : Preparing for the unavoidable impacts of climate change
KustantajaNCCARF (National Climate Change Adaptation Research Facility) and CSIRO
Julkaisupäivä2010
Sivut66
TilaJulkaistu - 2010
OKM-julkaisutyyppiB3 Vertaisarvioimaton artikkeli konferenssijulkaisussa
TapahtumaInternational Climate Change Adaptation Conference -
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