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Evaluating annual and seasonal patterns of suspended sediment loads in a semi-arid watershed, central Algeria

Rabah Mosbah, Bouchelkia Hamid, Belarbi Fadila, Millares Agustin

Journal of Water and Land Development

2021

no. 50

158--172

Soil loss is a major problem for watersheds management in semi-arid environments. The objective of the present study is to analyze the annual and seasonal patterns of suspended loads and quantify the specific sediment yields in a semi-arid environment of the Mazafran Watershed in central Algeria. The obtained information of water discharge and suspended sediment load, recorded during 19 years, was confronted with precipitation data in order to establish the relationships between theforcing agents and erosive processes. The specific sediment yield was estimated by assessing rating curve data under two types of identified responses. The obtained results allowedconfirming the seasonality on suspended sediment transport in the studied basin, which accounts for 56% of the total suspended sediment load estimated in winter. The mean annual suspended sediment is estimated at 17.52 Mg∙ha–1·y–1. The results highlighted that the type 2 event dominates the production of sediment in the study area in comparison with type 1 event. The analysis of the variability of rainfall erosivity index showed that there is a strong correlation between the annual precipitation and modified Fournier index (MFI), and a weak correlation with the monthly precipitation concentration index (PCI). Moreover, the spatial distribution of the modified Fournier index at the basin scale showed the highest precipitation aggressiveness in the Southern part of the study region for both type of events, whereas the precipitation aggressiveness low to moderate in the remaining part of the study region.

Land-use Assessment and its Influence on Spatial Distribution of Rainfall Erosivity: Case Study of Cameron Highlands Malaysia

Ul Mustafa Muhammad Raza, Sholagberu Abdulkadir Taofeeq, Syazwan Muhammad Asyraf, Yusof Khamaruzaman Wan, Hashim Ahmad Mustafa, Abdurrasheed Abdurrasheed S.

Journal of Ecological Engineering

2019

Vol. 20, nr 2

183--190

Over the years, Cameron Highlands have witnessed extensive land-use and land-cover (LULC) changes due to the massive agricultural and urbanization activities. This significantly contributed to the erosion problems in the area. Rainfall erosivity that measures the aggressiveness of raindrop in triggering soil erosion is one of its major components that could be influenced by the LULC changes in watersheds. However, the research relating to the LULC changes with the erosivity especially in the complex landscape is scarce. Hence, this study applies geographic information system (GIS) and remote sensing techniques to assess the LULC changes and their influence on the rainfall erosivity distribution in mountainous watershed of Cameron Highlands. Four Landsat images and the rainfall data from the period of thirty years were analysed for the development of LULC and erosivity maps respectively in ArcGIS environment. The study showed that the study area experienced immense land-use changes especially in agriculture and urbanization which affected the erosivity distribution. The LULC change for agriculture increased linearly in the last 30 years from 7.9% in 1986 to almost 16.4% in 2016. The results showed that urban development increased from 5.1% in 1986 to 11.4% in 2016. The increasing urbanization trend was targeted to meet up with tourism requirement in Cameron Highlands. However, forest class declined tremendously due to the exploration of land for agriculture practice and other various types of development. Watershed managers and other stakeholders should find this study beneficial in tackling erosion and its associated ecological challenges.