changes in Water resources availability

The major water uses are for irrigation, domestic, and the environmental requirements. Irrigation requires 1026.4 m³/month, while the environment flow requirements are 10% of the mean annual flow [13]. With the projected climate change, the availability of water resources availability will decrease by about 15.4%. This has adverse implications on irrigation water supply, environmental water require-ments, domestic water use, watering animals, and other uses. Table 7.3 shows the changes in water resources availability under climate change impacts.

7.11  Summary and conclusions

Global warming, due to the enhanced greenhouse effect, is likely to have significant effects on the hydro-logical cycle. The hydrohydro-logical cycle will be intensified, with more evaporation and more precipitation, but the extra precipitation will be unequally distributed around the globe. Some parts of the world may expe-rience significant reductions in precipitation, or major alterations in the timing of wet and dry seasons.

Assessing the implications of climate change on hydrology is essential for planning future water resources activities on a regional scale. This chapter analyzed the potential effects of climate change on the hydrology and water resources in general and the Nyanyadzi River catchment in eastern Zimbabwe in particular. The impacts of climate change on the hydrology of the Nyanyadzi River catchment were examined using the CSIRO climate model projections, two SRES emission scenarios (A2a and B2a), three points in time (2020, 2050, and 2080), and the 1961–1990 baseline climate data. Both scenarios predict increases in mean monthly temperature, rainfall, and evapotranspiration.

TABLE 7.3 Changes in Monthly Water Resources Availability (10³ m³) for Different Uses Scenario Baseline 2020A2a 2020B2a 2050A2a 2050B2a 2080A2a 2080B2a

Runoff 3169.2 2612.8 2609.7 2669.4 2589.6 2560.9 2672.6

Environment 316.9 261.3 261.0 266.9 259.0 256.1 267.3

Irrigation 1026.4 1026.4 1026.4 1026.4 1026.4 1026.4 1026.4

Others 1852.8 1325.1 1322.3 1376.0 1304.2 1278.4 1378.9

20

15

10

5

0 2020A2a 2020B2a 2050A2a 2050B2a 2080A2a 2080B2a Scenario

Runoff (%)

FIGuRE 7.5 Percentage changes in runoff relative to the 1961–1990 baseline.

Climate Change Impacts on Hydrology and Water Resources 125

Significant reductions of runoff are expected for all time periods under the two climate change scenarios. Changes in river flows the availability of water use in the catchment. Thus, sound water man-agement strategies need to be put in place.

references

1. Arnell, N.W. 1999. Climate change and global water resources. Global Environmental Change 9:

531–549.

2. Arnell, N.W. 2004. Climate change and global water resources: SRES emission and socio-economic scenarios. Global Environmental Change 14: 31–52.

3. Arnell, N. and Liu, C. 2001. Hydrology and water resources, Chapter 4. In: Mc Carthy, J.J., Canziani, O.F., Leary, N.A., Dokken, D.J., and White, K.S. (eds.), Climate Change 2001: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the third assessment report of the Intergovernmental Panel on climate change. Cambridge University Press, Cambridge, U.K., pp. 192–233.

4. Beck, L. and Bernauer, T. 2011. How will combined changes in water demand and climate affect water availability in the Zambezi River basin? Global Environmental Change 21: 1061–1072.

5. Bolding, A., Manzungu, E., and van der Zaag, P. 1996. Farmer initiated irrigation furrows:

Observations from the Eastern Highlands. In: Manzungu, E. and van der Zaag, P. (eds.), The Practice of Smallholder Irrigation: Case Studies from Zimbabwe. University of Zimbabwe Publications, Harare, Zimbabwe, pp. 191–218.

6. IPCC. 1995. Climate Change 1995: Impacts, Adaptations and Mitigation of Climate Change Contribution of Working Group II to the third assessment report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, U.K.

7. IPCC. 2000. Emissions scenarios 2000: Special report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, U.K.

8. IPCC. 2001. Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the third assessment report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, U.K.

9. IPCC. 2007. Climate Change 2007: Impacts Adaptation and Vulnerability. Contribution of Working Group II to the fourth assessment report of the Intergovernmental Panel on Climate Change.

Cambridge University Press, Cambridge, U.K.

10. IPCC. 2007. Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the fourth assessment report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, U.K.

11. IPCC. 2012. Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation. Cambridge University Press, Cambridge, U.K.

12. Kaczmarek, Z., Napiórkowski, J., and Strzepek, K. 1996. Climate change impacts on the water supply system in the Warta River catchment, Poland. International Journal of Water Resources Development 12: 165–180.

13. Mujere, N. 2011. River Flow Variations and Crop Yields at Nyanyadzi Irrigation Scheme. Lambert Academic Publishing, Saarbrücken, Germany.

14. Neff, R., Chang, H., Knight, C.G., Najjar, R.G., Yarnal, B., and Walker, H.A. 2000. Impact of climate variation and change on Mid-Atlantic Region hydrology and water resources. Climate Research 14:

207–218.

15. Pitchford, J.L., Wu, C., Lin, L., Petty, J.T., Thomas, R., Veselka, W.E., Welsch, D., Zegre, N., and Anderson, J.T. 2012. Climate change effects on hydrology and ecology of wetlands in the Mid-Atlantic Highlands. Wetlands 31:21–33.

16. UN. 1992. United Nations Framework Convention on Climate Change. UN, New York.

17. UNESCO. 2011. The impact of global change on water resources: The response of UNESCO’s International Hydrological Programme. UNESCO, Paris, France.

18. WaterAid. 2007. Climate change and water resources. WaterAid, London, U.K.

19. WMO/IPCC/UNEP. 2000. IPCC special report on emission scenarios: Summary for policy markers.

IPCC, England, U.K.

127 AuTHORS

Mohammad Reza Farzaneh was born in Iran in March 1986. He is currently a PhD student of Water Resources in Tarbiat Modarres University, Tehran, Iran. His scientific experiences include being author and coauthor for two international handbooks, adviser for six master theses, more than 40 under-review and published papers in conferences and journals; collaboration in national and international proj-ects such as study of climate change impact on African water resources; teaching climate change, GIS, hydrology, and water resources; and registration of four inventions.

Saeid Eslamian received his PhD from the University of New South Wales, Australia, with Professor David Pilgrim. He was a visiting professor in Princeton University, USA, and ETH Zurich, Switzerland.

He is currently an associate professor of hydrology in Isfahan University of Technology. He is founder and chief editor of Journal of Flood Engineering and International Journal of Hydrology Science and Technology. He has published more than 200 publications mainly in statistical and environmental hydrology and hydrometeorology.

Seyed Jalal E. Mirnezami was born in July 1987 in Iran. He received his BS degree in 2009 in agricultural-water engineering from University of Tehran, Iran. Jalal studied agricultural-water resources engineering in the same university and received his MSc in 2011. During this period, he studied modeling water resources and created a model for optimizing allocation of water in river basins. Following a desire to work on

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