Publication: Modelling and forecasting climate change impact on soil erosivity
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Date
2022-05-01
Authors
Mohtar, Zul Azmi
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Abstract
Precipitation and evaporation are other important drivers that can greatly affect soil structure. Thus the effects of higher average temperatures and more extreme rainfall distribution need to be investigated in order to anticipate how stability of soil might change with climate and adapt to any negative consequences on the conditions of local weather. Impact of past, present and future climate characteristics on soil activity can be assessed by historical information, geomorphological evidence and modelling of soil hydrology and mechanics. To analyze the potential of climate change impacts on soil stability, several modelling approach need to be developed. The aim for this research is to model and forecast the soil stability index using the time series models to help control the adverse impact of climate change on human life. Eight rainfall monitoring stations Air Itam, Bukit Berapit and Permatang Binjai located in Pulau Pinang, Sg. Raja and Kompleks Rumah Muda located in Kedah, Ulu Kinta and Politeknik Ungku Omar (PUO) located at Perak and Padang Besar, located at Perlis representative four states covered northern region of Peninsular Malaysia with 30 years of rainfall data from 1983 to 2012 were used in this research. Annual mean rainfall data are used to assess and determine the characteristic and trend of rainfall for 30 years. In terms of the total amount of rainfall, the highest was found in Air Itam, Pulau Pinang and the lowest in Padang Besar, Perlis. In general, the trend analysis showed the positive trend (increased) except for two stations (Padang Besar and Ulu Kinta) have a
decreasing trend. Thirty years of rainfall data also were used to determine the relationship between rainfall and soil stability by using three indexes which is Fournier (F), Fournier Modified (FM) and ROM scale. The value of FM is slightly higher compared to value of F. The difference occurred because of amount of rainfall value that used. Three types of time series models were used named autoregressive (AR), moving-average (MA) and autoregressive moving-average (ARMA). The best time series model using Fournier for Air Itam is MA(7), Bukit Berapit is AR(1), Permatang Binjai is MA(7) Politeknik Ungku Omar (PUO) is MA(9), Ulu Kinta is MA(9), Rumah Muda is AR(10), Sg. Raja is AR(10) and Padang Besar is
ARMA(1,1). While the best time series model for Fournier Modified for Air Itam is ARMA (2,3), Bukit Berapit is MA(10), Permatang Binjai ARMA(2,1), Politeknik Ungku Omar (PUO) is ARMA(3,2), Ulu Kinta and Rumah Muda are MA(7) and Sg. Raja and Padang Besar are ARMA(2,3) and MA(10) respectively. Based on the rainfall erosivity index (Fournier and Fournier Modified) and total rainfall the risk map for northern region of Peninsular Malaysia was produced.