Land cover and climate change effects on streamflow and sediment yield: a case study of Tapacurá River basin, Brazil

J Y G Santos,A M Silva,J G Carvalho Neto,C A G Santos,S M G L Montenegro,R M Silva

doi:10.5194/piahs-371-189-2015

Abstract

Abstract. This study assesses the impact of the land use and climate changes between 1967–2008 on the streamflow and sediment yield in Tapacurá River basin (Brazil) using the Soil and Water Assessment Tool (SWAT) model. The model was calibrated and validated by comparing simulated mean monthly streamflow with observed long-term mean monthly streamflow. The obtained R2 and Nash–Sutcliffe efficiency values to streamflow data were respectively 0.82 and 0.71 for 1967–1974, and 0.84 and 0.82 for 1995–2008. The results show that the land cover and climate change affected the basin hydrology, decreasing the streamflow and sediment yield (227.39 mm and 18.21 t ha−1 yr−1 for 1967–1974 and 182.86 mm and 7.67 t ha−1 yr−1 for 1995–2008). The process changes are arising mainly due to the land cover/use variability, but, mainly due to the decreasing in the rainfall rates during 1995–2008 when compared with the first period analysed, which in turn decreased the streamflow and sediments during the wet seasons and reduced the base flow during the dry seasons.

Highlights

Runoff and sediment yield processes in a basin are sensitive to the changes of climate and land uses
This study assesses the impact of the land use and climate changes between 1967–2008 on the streamflow and sediment yield in Tapacurá River basin (Brazil) using the Soil and Water Assessment Tool (SWAT) model
It is concluded that the decrease in forest land and grassland is accompanied by the increase in agricultural and built up areas, (b) the hydrological model SWAT adequately simulates the runoff with satisfactory R2 and Nash–Sutcliffe efficiency (NSE), (c) the process changes are arising due to the land cover/use variability, but mainly due to the decreasing in the rainfall depth during 1995–2008 when compared with the first period analysed, which in turn decreased the streamflow and sediments yield during the wet seasons and reduced the base flow during the dry seasons

Summary

Introduction

Runoff and sediment yield processes in a basin are sensitive to the changes of climate and land uses. Based distributed hydrological models, whose parameters have a physical representation for the spatial variability of hydrological processes and land uses are capable of simulating the impact of climate change and human activities on hydrological cycle (Dos Santos et al, 2014). Runofferosion models are increasingly being used to simulate complex water resource systems including simulation for the impact of land use and climate change on water resources in river basins during past and recent decades. In areas characterized by strong seasonal variability, as is the case of the Tapacurá River basin. The Tapacurá River basin covers an area of about 470 km, and is located in the Zona da Mata region in the state of Pernambuco, north-eastern Brazil, between coordinates 7◦58 0 S and 8◦13 0 S, and 35◦5 0 W and 35◦30 0 W (Fig. 1)

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Conclusion