Abstract
Urban expansion substantially alters the impervious areas in a catchment, which in turn affects surface runoff and sediment yield in the downstream areas. In this study, the Land Transformation Model (LTM) was used to forecast the urban land expansion in a catchment, whilst future land use maps were employed according to the Soil Conservation Service Curve Number method (SCS-CN) and the Modified Universal Soil Loss Equation (MUSLE) model, so as to examine the urbanization effects on runoff and sediment yield production respectively. Compared to pristine conditions, urban land is anticipated to increase from 6% in 1979 to 31% by 2027. The latter expansion pointed to an increase of peak discharge by 2.2–2.6 times and of flood volume by 1.6–2.1 times, with the sediment yield ranging between 0.47 to 1.05 t/ha for the upcoming 2027 period. Furthermore, the urban sprawl effects on all the latter variables were more profound during short duration storm events. Forecasting urban expansion through integrated artificial neural networks (ANN) and geographic information system (GIS) techniques, in order to calculate the associated design storm hydrograph and sediment yield, is of great importance, in order to properly plan and design hydraulic works that can sustain future urban development.
Highlights
Since 1950, the global urban population has rapidly increased from 751 million to 4.2 billion in 2018 and by 2050 two thirds of the world’s population is expected to live in urban areas [1]
The objectives of the present paper are: firstly, to use three reference land use maps of the Elaionas catchment for the years 1979, 1996 and 2007 in the Land Transformation Model (LTM) [27,28], so as to forecast the urban sprawl for the year 2027; secondly, based on both the recorded land use changes and the future urban sprawl scenarios developed by the LTM, to examine the effects of current and future urban expansion on the design hydrograph, and, thirdly, to estimate the impact of urban sprawl on the associated sediment yield generated by the latter storm events
Recent studies worldwide on urbanization prospects reveal that there is an upward shift on urban population rates, which is associated with urban land expansion [1,2,3]
Summary
Since 1950, the global urban population has rapidly increased from 751 million to 4.2 billion in 2018 and by 2050 two thirds of the world’s population is expected to live in urban areas [1]. In Greece, which has suffered greatly due to eight hard years of economic recession and employment rates are higher in rural rather than urban areas, 79.1% of its population is still living in urban areas [1,2]. This global rapid urban population growth trend is associated with an accelerated urban sprawl, which may offer certain important benefits to the urban population in terms of higher employment rates, better infrastructure and a higher income but is associated with some adverse effects on the environment and on natural resources. Due to the urban sprawl, the mean annual surface air temperature in cities has been undergoing excessive warming [4], the habitat potential and biodiversity
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