Qatar is going through a rapid infrastructure development in recent years. This remarkable development has prompted the need for Qatar to have a comprehensive and world class guidelines or code of practices for planning and infrastructure design to meet future demand. The Qatar National Vision (QNV 2030) defined long-term development strategies for advancing sustainable development. In order to achieve goals of QNV, Ministry of Municipality and Environment (MME) of Qatar is currently undertaking out a comprehensive rainfall study for estimation of design rainfall for Qatar. This study is aimed at preparation of a single comprehensive National design guidelines titled Qatar Rainfall and Runoff (QRR) manual for the design of storm and surface water infrastructure in Qatar.
For design and operation of water infrastructure, erosion control and many other environmental and stormwater management tasks, design rainfall is a fundamental input. The developed countries have spent millions of dollars to derive national standards of design rainfalls, generally known as intensity-duration-frequency (IDF) curves. For Qatar, the old IDF data was developed in 1991 based on a limited data set and basic statistical approaches. Since then there have been significant developments in statistical techniques to derive IDF data and moreover at many locations in Qatar, the length of the observed rainfall data has increased notably. Under this project, additional new IDF curves will be developed by utilizing latest data, and assess impact of climate change in design rainfall estimation.
Qatar is mainly covered by barren desert with relatively flat topography. The climate of Qatar is dominated by mild winters and very hot summers. Rainfall mainly occurs in the period from October to May, with significant inter-annual variability. The months from June to September are usually dry. Temperatures range from 7 to 45oC. The average annual rainfall values for Qatar are found to be in the range of 55.5–99 mm. A sharp gradient in average annual rainfall was noticed, with north having higher values than the south.
Data & methodology
The study examined rainfall data from over 30 stations located in Qatar and nearby Gulf countries. The rainfall analysis in arid regions such as Qatar appears to be a challenge due to the limited availability of high resolution, long record rainfall data of acceptable quality and significant year to year variability. The method of L-moments is employed for derivation of new set of IDF data for Qatar. This approach reduces the impacts of sampling variability on the analysis. The data used in this study based on a larger dataset and more advanced statistical techniques than was used since the collection of the 1991 IDF curves, therefore the new IDF data presents a solid scientific basis for stormwater system design, flood and environmental studies.
“The study examined rainfall data from over 30 stations located in Qatar and nearby Gulf countries”
Climate change can affect the magnitude, frequency and spatial variability of rainfall. As per IPCC (Intergovernmental Panel on Climate Change), the rainfall patterns will be more extreme in the future; some arid regions will be even drier, and wet regions will be wetter. A statistical trend analysis is therefore being carried out as part of this study for evaluating the possible impacts of climatic change and climate variability on rainfall data in Qatar.
A number of rainfall characteristics were examined including annual rainfall, monthly rainfall, daily maximum rainfall and the number of rainy days using Mann–Kendall (MK) and Spearman’s Rho (SR) tests. In general, the trend tests have shown both positive and negative trends for all the 15 precipitation indices throughout the country. The preliminary findings of this investigation indicate that in general, rainfall in Qatar is changing.
The findings of this study provide important insights into the nature of rainfall variability in Qatar, which will be useful in water resources planning tasks in Qatar and nearby countries.
Abdullah Al Mamoon
Senior Infrastructure Engineer
Abeer Ahmad Abd Alkader
Senior Infrastructure Engineer
Ministry of Municipality and Environment