scholarly journals Climate or land cover variations: what is driving observed changes in river peak flows? A data-based attribution study

2019 ◽  
Vol 23 (2) ◽  
pp. 871-882 ◽  
Author(s):  
Jan De Niel ◽  
Patrick Willems

Abstract. Climate change and land cover changes are influencing the hydrological regime of rivers worldwide. In Flanders (Belgium), the intensification of the hydrological cycle caused by climate change is projected to cause more flooding in winters, and land use and land cover changes could amplify these effects by, for example, making runoff on paved surfaces faster. The relative importance of both drivers, however, is still uncertain, and interaction effects between both drivers are not yet well understood. In order to better understand the hydrological impact of climate variations and land cover changes, including their interaction effects, we fitted a statistical model for historical data over 3 decades for 29 catchments in Flanders. The model is able to explain 60 % of the changes in river peak flows over time. It was found that catchment characteristics explain up to 18 % of changes in river peak flows, 6 % of changes in climate variability and 8 % of land cover changes. Steep catchments and catchments with a high proportion of loamic soils are subject to higher peak flows, and an increase in urban area of 1 % might cause increases in river peak flows up to 5 %. Interactions between catchment characteristics, climate variations and land cover changes explain up to 32 % of the peak-flow changes, where flat catchments with a low loamic soil content are more sensitive to land cover changes with respect to peak-flow anomalies. This shows the importance of including such interaction terms in data-based attribution studies.

2018 ◽  
Author(s):  
Jan De Niel ◽  
Patrick Willems

Abstract. Climate change and land cover changes are influencing the hydrological regime of our rivers. The intensification of the hydrological cycle caused by climate change is projected to cause more flooding in winters and an increased urbanization could amplify these effects by a quicker runoff on paved surfaces. The relative importance of both drivers, however, is still uncertain and interaction effects between both drivers are not yet well understood. In order to better understand the hydrological impact of climate variability and land cover changes, including their interaction effects, we fitted a statistical model to historical data over 3 decades for 29 catchments in Flanders, covering various catchment characteristics. It was found that the catchment characteristics explain up to 18 % of changes in river peak flows, climate variability 6 % and land cover changes 8 %. Interaction terms explain up to 32 %. An increase in urban area of +1 % might cause increases in river peak flows up to +5 %.


Author(s):  
Philip Mzava ◽  
Patrick Valimba ◽  
Joel Nobert

Abstract Over the past half-century, the risk of urban flooding in Dar es Salaam has increased due to changes in land cover coupled with climatic changes. This paper aimed to quantify the impacts of climate and land-cover changes on the magnitudes and frequencies of flood runoffs in urban Dar es Salaam, Tanzania. A calibrated and validated SWAT rainfall-runoff model was used to generate flood hydrographs for the period 1969–2050 using historical rainfall data and projected rainfall based on the CORDEX-Africa regional climate model. Results showed that climate change has a greater impact on change in peak flows than land-cover change when the two are treated separately in theory. It was observed that, in the past, the probability of occurrence of urban flooding in the study area was likely to be increased up to 1.5-fold by climate change relative to land-cover change. In the future, this figure is estimated to decrease to 1.1-fold. The coupled effects of climate and land-cover changes cause a much bigger impact on change in peak flows than any separate scenario; this scenario represents the actual scenario on the ground. From the combined effects of climate and land-cover changes, the magnitudes of mean peak flows were determined to increase between 34.4 and 58.6% in the future relative to the past. However, the change in peak flows from combined effects of climate and land-cover changes will decrease by 36.3% in the future relative to the past; owing to the lesser variations in climate and land-cover changes in the future compared with those of the past.


2021 ◽  
Author(s):  
Jolanda Theeuwen ◽  
Obbe Tuinenburg ◽  
Arie Staal ◽  
Bert Hamelers ◽  
Stefan Dekker

<p>Weather extremes are predicted to be more intense and recurrent in the future because of climate change. Previous studies show that Mediterranean regions around the world are especially vulnerable to extreme events that depend on the hydrological cycle, such as droughts and floods. Land use and land cover changes may enhance these events, as they influence the exchange of moisture and energy between the land surface and atmosphere. To better understand the role of extremes in a future climate, we need to improve our understanding of the impact of climate change on the terrestrial hydrological cycle. Atmospheric transport of moisture is an important element of this cycle as it determines the allocation of evaporated moisture. We are especially interested in the sink-source relations. So, how land contributes to the moisture recycling over land further away, and the origin of the precipitation over, the so-called precipitation-shed. Tuinenburg et al. (2020) recently published a dataset with high-resolution global atmospheric moisture connections from evaporation to precipitation, allowing novel detailed insight. We used this dataset to study temporal variability in atmospheric moisture connections for five different regions with Mediterranean climates. We investigated the dependency of different Mediterranean regions on local and remote moisture sources, and how this dependency varies throughout the year. Large differences in the spatial pattern of moisture recycling over land showed to exist between the Mediterranean regions on the Northern and Southern Hemisphere. Additionally, of all regions, the Mediterranean Basin shows the largest temporal variability. This information is essential to study how local changes in land use and land cover have and will further affect the hydrological cycle in local and remote regions. This helps us to understand how climate extremes could change in the future as a result of land use and land cover changes.  </p><p> </p><p>Tuinenburg, O. A., Theeuwen, J. J. E., and Staal, A. Global evaporation to precipitation flows obtained with Lagrangian atmospheric moisture tracking, PANGAEA, https://doi.org/10.1594/PANGAEA.912710, 2020.</p>


2019 ◽  
Vol 11 (24) ◽  
pp. 7053 ◽  
Author(s):  
Carina Colman ◽  
Paulo Oliveira ◽  
André Almagro ◽  
Britaldo Soares-Filho ◽  
Dulce Rodrigues

The Pantanal biome integrates the lowlands of the Upper Paraguay Basin (UPB), which is hydrologically connected to the biomes of the Cerrado and Amazon (the highlands of the UPB). The effects of recent land-cover and land-use (LCLU) changes in the highlands, combined with climate change, are still poorly understood in this region. Here, we investigate the effects of soil erosion in the Brazilian Pantanal under climate and LCLU changes by combining different scenarios of projected rainfall erosivity and land-cover management. We compute the average annual soil erosion for the baseline (2012) and projected scenarios for 2020, 2035, and 2050. For the worst scenario, we noted an increase in soil loss of up to 100% from 2012 to 2050, associated with cropland expansion in some parts of the highlands. Furthermore, for the same period, our results indicated an increase of 20 to 40% in soil loss in parts of the Pantanal biome, which was associated with farmland increase (mainly for livestock) in the lowlands. Therefore, to ensure water, food, energy, and ecosystem service security over the next decades in the whole UPB, robust and comprehensive planning measures need to be developed, especially for the most impacted areas found in our study.


2017 ◽  
Vol 10 (4) ◽  
Author(s):  
Hassan Khosravi ◽  
Ali Azareh ◽  
Hadi Eskandari Dameneh ◽  
Elham Rafiei Sardoii ◽  
Hamed Eskandari Dameneh

2021 ◽  
pp. 509-525
Author(s):  
Shahidul Islam ◽  
Mingguo Ma ◽  
Md. Nuralam Hossain ◽  
Sumon Ganguli ◽  
Md Nazirul Islam Sarker

2020 ◽  
Author(s):  
Marcus Buechel ◽  
Simon Dadson ◽  
Louise Slater

<p>Climate change is set to increase the magnitude and frequency of fluvial flooding in many regions across the world, making it a growing risk to billions of people living near rivers. Changing drainage basin land cover and hydrological connectivity further complicates how these streamflow extremes may evolve. Engineered solutions to mitigate the risk of future high magnitude runoff events to populations may no longer be suitable to meet these needs due to these changes in climate and land cover.</p><p>By reducing the level of global CO<sub>2</sub> emissions, climate models predict that we can reduce the severity of climate change impacts upon communities. To achieve the goals set by the Paris Agreement to limit global warming, the UK has proposed a range of policies to reach net zero carbon emissions by 2050. One of these proposals includes widespread afforestation across the UK. Where to plant this woodland and the scale of impact it may have on the future hydrological cycle is currently unquantified. This project seeks to investigate three aspects of how future streamflow trends my change due to afforestation in respect to: woodland location, differing afforestation rates, and the hydrological responsiveness of drainage basins to land cover changes.</p><p>Physics-based models provide the possibility to explore the relative importance of climate and land cover on future streamflow trends, both together and separately. The Joint UK Land Environment Simulator (JULES) is used to explore catchment responses across the UK to potential extreme weather events with theoretical changes in land cover at a 1 km resolution. Theoretical land cover scenarios of afforestation were generated according to proximity to existing land cover, drainage basin structure and proposed afforestation sites. An extreme precipitation scenario (the winter of 2013/14) is explored to comprehend streamflow regime response to high magnitude precipitation events caused by changing climate and land cover using the Weather@home perturbed model ensembles and CHESS-met datasets. This approach provides the potential to explore how increasing afforestation could change the discharge dynamics of landscapes across the UK and thus its potential benefits and drawbacks to flood risk management. </p><p>Results show how potential land cover changes will impact streamflow response to storms across the UK. These results help provide a clearer picture of how changing landscape systems impact river response to external climatic forcing and may provide evidence for management and policy strategies tailored to the requirements of individual drainage basins to reduce the risk of flooding upon downstream populations.</p>


Author(s):  
P. Skougaard Kaspersen ◽  
N. Høegh Ravn ◽  
K. Arnbjerg-Nielsen ◽  
H. Madsen ◽  
M. Drews

Abstract. The extent and location of impervious surfaces within urban areas due to past and present city development strongly affects the amount and velocity of run-off during high-intensity rainfall and consequently influences the exposure of cities towards flooding. The frequency and intensity of extreme rainfall are expected to increase in many places due to climate change and thus further exacerbate the risk of pluvial flooding. This paper presents a combined hydrological-hydrodynamic modelling and remote sensing approach suitable for examining the susceptibility of European cities to pluvial flooding owing to recent changes in urban land cover, under present and future climatic conditions. Estimated changes in impervious urban surfaces based on Landsat satellite imagery covering the period 1984–2014 are combined with regionally downscaled estimates of current and expected future rainfall extremes to enable 2-D overland flow simulations and flood hazard assessments. The methodology is evaluated for the Danish city of Odense. Results suggest that the past 30 years of urban development alone has increased the city's exposure to pluvial flooding by 6% for 10-year rainfall up to 26% for 100-year rainfall. Corresponding estimates for RCP4.5 and RCP8.5 climate change scenarios (2071–2100) are in the order of 40 and 100%, indicating that land cover changes within cities can play a central role for the cities' exposure to flooding and conversely also for their adaptation to a changed climate.


2018 ◽  
Author(s):  
Ane Zabaleta ◽  
Eneko Garmendia ◽  
Petr Mariel ◽  
Ibon Tamayo ◽  
Iñaki Antigüedad

Abstract. Climate change impacts on the hydrological cycle are altering the quantity, quality, and temporal distribution of riverine discharge, necessitating a more rigorous consideration of changes in land cover and land use. This study establishes relationships between different land cover combinations (e.g., percentages of forest – both native and exotic – and pastureland) and hydrological services, using hydrological indices estimated at annual and seasonal time scales in an area with a steep precipitation gradient (900–2600 mm y−1). Using discharge data from 20 catchments in the Bay of Biscay, a climate transition zone, the study applied multiple regression models to better understand how the interaction between precipitation and land cover combinations influence hydrological services. Findings showed the relationship between land cover combinations and hydrological services is highly dependent on the amount of precipitation, even in a climatically homogeneous and relatively small area. In general, in the Bay of Biscay area, the greater presence of any type of forests is associated with lower annual water resources, especially with greater percentages of exotic plantations and high annual precipitation. Where precipitation is low, forests show more potential to reduce annual and winter high flows than pasturelands, but this potential decreases as annual or seasonal precipitation increases. As annual precipitation increases, low flows increase as the percentage of exotic plantations decreases and pasturelands increase. Results obtained in this study improve understanding of the multiple effects of land cover on hydrological services, and illustrate the relevance of land planning to the management of water resources, especially under a climate change scenario.


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