Simulation of Sediment Yield in a Semi-Arid River Basin under Changing Land Use: An Integrated Approach of Hydrologic Modelling and Principal Component Analysis

Charles Gyamfi,Ramadhan Salim,Julius Ndambuki

doi:10.3390/su8111133

Abstract

Intensified human activities over the past decades have culminated in the prevalence of dire environmental consequences of sediment yield resulting mainly from land use changes. Understanding the role that land use changes play in the dynamics of sediment yield would greatly enhance decision-making processes related to land use and water resources management. In this study, we investigated the impacts of land use and cover changes on sediment yield dynamics through an integrated approach of hydrologic modelling and principal component analysis (PCA). A three-phase land use scenario (2000, 2007 and 2013) employing the “fix-changing” method was used to simulate the sediment yield of the Olifants Basin. Contributions in the changes in individual land uses to sediment yield were assessed using the component and pattern matrixes of PCA. Our results indicate that sediment yield dynamics in the study area is significantly attributed to the changes in agriculture, urban and forested lands. Changes in agriculture and urban lands were directly proportional to sediment yield dynamics of the Olifants Basin. On the contrary, forested areas had a negative relationship with sediment yield indicating less sediment yield from these areas. The output of this research work provides a simplistic approach of evaluating the impacts of land use changes on sediment yield. The tools and methods used are relevant for policy directions on land and water resources planning and management.

Highlights

Sedimentation is one of the key environmental problems arising from soil erosion and is widely acknowledged throughout the world owing to its ramifications on water resources quality, reservoir capacity reduction and low agricultural productivity due to the removal of top rich nutrient soils [1,2,3,4,5,6,7,8,9,10]
As CN2 is a function of land use/cover (LULC) influencing other parameters such as antecedent moisture content, it could be inferred that changes in LULC will have a greater implication on surface runoff and sediment yield
The study investigated the impacts of land use and land cover changes on sediment yield in the water-stressed Olifants Basin in South Africa using hydrologic modelling and principal component analysis (PCA)

Summary

Introduction

Sedimentation is one of the key environmental problems arising from soil erosion and is widely acknowledged throughout the world owing to its ramifications on water resources quality, reservoir capacity reduction and low agricultural productivity due to the removal of top rich nutrient soils [1,2,3,4,5,6,7,8,9,10]. The interplay between geology, soil texture, topography, land use and climate change are noted as stimuli to the quantity of sediment loads generated within and transported out of watersheds [3,11]. Current studies indicate that sediment production and transport in watersheds are intrinsically linked to the synergic forces of climate and land use [12,13,14]. Others are of the view that land use change and soil management practices wield a greater influence on sediment fluxes compared to climate variability [17,18,19,20,21]. The degree to which the frequency and magnitude of sediment fluxes are impacted upon by climate change and land use still remains a subject of debate

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