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Doctoral thesis, 2021

Impacts of land use change on river streamflow and water quality in a semi-arid catchment : assessment of a catchment under rapid and uncontrolled urbanisation

Gossweiler, Benjamin

Abstract

The ongoing degradation of water quality and streamflow in rivers and streams worldwide is mainly due to human action through global land use change, particularly urbanisation. Population growth and economic development are major drivers of urbanisation, which causes environmental problems such as high water demand and solid waste and wastewater generation. This thesis describes the impacts of three decades of unregulated urbanisation and land use change on water quality and streamflow in the semi-arid Rocha River catchment in Bolivia. Remote sensing and geographic information systems (GIS) based on Landsat imagery were used to detect land use change, while an index-based approach was developed to classify and compare river water quality and locate priority source areas (PSAs) of pollution. Correlation analysis was used to examine relationships between different land uses and water quality. The Soil and Water Assessment Tool (SWAT) model was employed to simulate streamflow and total nitrogen and total phosphorus transport in the catchment, based on monthly data. The results showed strong increases in the area of human settlements, forest and cropland, while semi-natural land area generally decreased. Water quality decreased over time and from catchment headwaters to outlet, and human settlements were identified as PSAs of pollution. Human settlements were also associated with decreasing water quality (p<0.01) and pollution from PSAs (p<0.05). SWAT modelling proved good (Kling-Gupta efficiency, KGE) for streamflow, satisfactory for total phosphorus, and poor for total nitrogen. Simulated mean annual streamflow (13.9-23.3 m3 s-1), total nitrogen (270.3-550.7 ton year-1) and total phosphorus (83.1-170.5 ton year-1) loads increased over time, with nutrient transport increasing overall from catchment headwaters to outlet. These deleterious impacts of urbanisation-related land use change in the Rocha River catchment demonstrate the need for effective remedial measures, including continuous monitoring, pollution mitigation and water quality restoration.

Keywords

Landsat; maximum likelihood; long-term variations; point and non-point pollution sources; hydrological modelling; nutrient transport; Cochabamba; Bolivia

Published in

Acta Universitatis Agriculturae Sueciae
2021, number: 2021:64
ISBN: 978-91-7760-805-9, eISBN: 978-91-7760-806-6
Publisher: Department of Soil and Environment, Swedish University of Agricultural Sciences

Authors' information

Gossweiler, Benjamin
Swedish University of Agricultural Sciences, Department of Soil and Environment

UKÄ Subject classification

Water Engineering
Geosciences, Multidisciplinary
Environmental Sciences related to Agriculture and Land-use

URI (permanent link to this page)

https://res.slu.se/id/publ/113353