Mitigation of time series approach on climate change adaptation on rainfall of Wadi Al-Aqiq, Madinah, Saudi Arabia

Abstract

Rainfall record plays a significant role in assessment of climate change, water resource planning and management. In arid region, studies on rainfall are rather scarce due to intricacy and constraint of the available data. Most available studies use more advanced approaches such as A2 scenario, General Circulation Models (GCM) and the like, to study the temporal dynamics and make projection on future rainfall. However, those models take no account of the data patterns and its predictability. Therefore, this study uses time series analysis methodologies such as Mann- Kendall trend test, de-trended fluctuation analysis and state space time series approaches to study the dynamics of rainfall records of four stations in and around Wadi Al-Aqiq, Kingdom of Saudi Arabia (KSA). According to Mann-Kendall trend test there are decreasing trend in three out of the four stations. The detrended fluctuation analysis revealed two distinct scaling properties that spells the predictability of the records and confirmed by state space methods.

Rekod hujan memainkan peranan penting dalam penilaian perubahan iklim dan perancangan dan pengurusan sumber air. Di kawasan gersang, kajian mengenai hujan agak sukar didapati kerana kerumitan dan kekangan data yang ada. Kebanyakan kajian menggunakan kaedah yang lebih canggih seperti A2 senario, model GCM dan sebagainya, untuk mengkaji dinamik secara sementara dan membuat unjuran hujan akan datang. Walau bagaimanapun, model-model tersebut tidak mengambil kira corak data dan kebolehramalan. Oleh itu, kajian ini menggunakan siri analisis metodologi masa seperti Mann- Kendall ujian trend, de-trend analisis turun naik dan pendekatan siri masa terhadap keadaan ruang untuk mengkaji dinamik rekod hujan sebanyak empat stesen di dalam dan sekitar Wadi Al-Aqiq, Kerajaan Arab Saudi (KSA). Menurut ujian trend MannKendall, terdapat penurunan trend terhadap tiga daripada empat stesen. Analisis turun naik de-trend mendedahkan dua sifat skala berbeza yang menjelaskankan kebolehramalan rekod dan disahkan oleh kaedah keadaan ruang.