Land use change impacts on floods at the catchment scale : challenges and opportunities for future research
Vienna University of Technology1, University of Florence2, University of Bern3, Newcastle University4, University of Natural Resources and Life Sciences, Vienna5, University of Padua6, Centre national de la recherche scientifique7, Spanish National Research Council8, Slovak Academy of Sciences9, University of Kiel10, Slovak University of Technology in Bratislava11, University of Innsbruck12, University of Rostock13, University of Kassel14, University of Hradec Králové15, Lancaster University16, University of Vienna17, Wageningen University and Research Centre18
TL;DR: In this article, the authors identified research gaps in understanding flood changes at the catchment scale caused by changes in forest management, agricultural practices, artificial drainage, and terracing, and proposed strategies in addressing these gaps.
Abstract: Research gaps in understanding flood changes at the catchment scale caused by changes in forest management, agricultural practices, artificial drainage, and terracing are identified. Potential strategies in addressing these gaps are proposed, such as complex systems approaches to link processes across time scales, long-term experiments on physical-chemical-biological process interactions, and a focus on connectivity and patterns across spatial scales. It is suggested that these strategies will stimulate new research that coherently addresses the issues across hydrology, soil and agricultural sciences, forest engineering, forest ecology, and geomorphology.
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Vienna University of Technology1, Polytechnic University of Turin2, University of Potsdam3, Swedish Meteorological and Hydrological Institute4, University of Messina5, Czech Hydrometeorological Institute6, University of Split7, University of Padua8, University of Zagreb9, University of Bologna10, University of Naples Federico II11, Moscow State University12, Dokuz Eylül University13, European Centre for Medium-Range Weather Forecasts14, University of Bath15, Slovak University of Technology in Bratislava16, Finnish Environment Institute17, University of Liverpool18, University of Architecture, Civil Engineering and Geodesy19, Technical University of Madrid20, Helmholtz Centre for Environmental Research - UFZ21, ETH Zurich22, Maynooth University23, Polish Academy of Sciences24, ODESSA25, University of Ljubljana26, Roma Tre University27, Norwegian Water Resources and Energy Directorate28, Polytechnic University of Tirana29, University of Belgrade30
TL;DR: Analysis of a comprehensive European flood dataset reveals regional changes in river flood discharges in the past five decades that are broadly consistent with climate model projections for the next century, suggesting that climate-driven changes are already happening and supporting calls for the consideration of climate change in flood risk management.
Abstract: Climate change has led to concerns about increasing river floods resulting from the greater water-holding capacity of a warmer atmosphere1. These concerns are reinforced by evidence of increasing economic losses associated with flooding in many parts of the world, including Europe2. Any changes in river floods would have lasting implications for the design of flood protection measures and flood risk zoning. However, existing studies have been unable to identify a consistent continental-scale climatic-change signal in flood discharge observations in Europe3, because of the limited spatial coverage and number of hydrometric stations. Here we demonstrate clear regional patterns of both increases and decreases in observed river flood discharges in the past five decades in Europe, which are manifestations of a changing climate. Our results—arising from the most complete database of European flooding so far—suggest that: increasing autumn and winter rainfall has resulted in increasing floods in northwestern Europe; decreasing precipitation and increasing evaporation have led to decreasing floods in medium and large catchments in southern Europe; and decreasing snow cover and snowmelt, resulting from warmer temperatures, have led to decreasing floods in eastern Europe. Regional flood discharge trends in Europe range from an increase of about 11 per cent per decade to a decrease of 23 per cent. Notwithstanding the spatial and temporal heterogeneity of the observational record, the flood changes identified here are broadly consistent with climate model projections for the next century4,5, suggesting that climate-driven changes are already happening and supporting calls for the consideration of climate change in flood risk management. Analysis of a comprehensive European flood dataset reveals regional changes in river flood discharges in the past five decades that are consistent with models suggesting that climate-driven changes are already happening.
558 citations
Günter Blöschl1, Marc F. P. Bierkens2, António Chambel3, Christophe Cudennec4 +209 more•Institutions (124)
TL;DR: In this article, a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts is described. But despite the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work.
Abstract: This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through online media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focused on the process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come.
469 citations
TL;DR: In this paper, the authors use historical records of harvester and tractor weights to simulate how the weight increase has changed soil stresses and bulk density of arable soil, and to predict impacts on the mechanical resistance for root growth and on soil hydraulic properties.
Abstract: Soil compaction caused by vehicular traffic adversely affects key soil functions and ecosystem services that soils provide. Although compaction is a well-recognized problem, it remains challenging to quantify the economic and ecological costs of compaction. The mechanization in agriculture has resulted in a steady increase in weight of farm vehicles. It is reasonable to assume that this has exacerbated soil compaction, but there is little quantitative knowledge on the development of compaction levels in arable soils. To quantify these trends, we use historical records of harvester and tractor weights to simulate how the weight increase has changed soil stresses and bulk density of arable soil, and to predict impacts on the mechanical resistance for root growth and on soil hydraulic properties. Our simulations show a clear increase in soil stress levels with higher bulk density and mechanical penetration resistance, and a decrease in soil hydraulic conductivity in agreement with available data. We show that increased mechanical resistance has resulted in decreased root elongation rates and consequently prolonged the time required for roots to reach a certain soil depth. The historical changes of compaction levels and associated limitations on root elongation rates coincide with a stagnation in crop yields in the 1990s observed for cereals in many countries. Our calculations illustrate that the historical increase in compaction levels has drastically decreased saturated hydraulic conductivity and water storage capacity of subsoils. We speculate that this has contributed to the increase in the incidence and severity of flood events during recent decades in Europe. Finally, we take Sweden as an example and estimate annual compaction costs due to agricultural productivity loss and flooding damage of several hundred M€ yr−1 for Sweden. Considering the continuation of upwards trends in the average weight of farm machinery and the projected increase in extreme weather events, the costs of soil compaction are likely to escalate. The study highlights that we have likely exceeded the acceptable loads, and that future agricultural operations must consider the inherent mechanical limit of soil.
182 citations
Vienna University of Technology1, Polytechnic University of Turin2, University of Barcelona3, University of Augsburg4, Academy of Sciences of the Czech Republic5, Masaryk University6, Royal Meteorological Institute7, University of Liverpool8, Stockholm University9, Norwegian Water Resources and Energy Directorate10, University of Porto11, Spanish National Research Council12, Norwegian University of Science and Technology13, National Research Council14, VRVis15, Czech Hydrometeorological Institute16, University of Freiburg17, Central Institution for Meteorology and Geodynamics18, Russian Academy of Sciences19, Moscow State University20, University of Zagreb21, University of Almería22, University of Bern23, Utrecht University24, Slovak University of Technology in Bratislava25
TL;DR: It is shown that the past three decades were among the most flood- rich periods in Europe in the past 500 years, and that this period differs from other flood-rich periods in terms of its extent, air temperatures and flood seasonality.
Abstract: There are concerns that recent climate change is altering the frequency and magnitude of river floods in an unprecedented way1. Historical studies have identified flood-rich periods in the past half millennium in various regions of Europe2. However, because of the low temporal resolution of existing datasets and the relatively low number of series, it has remained unclear whether Europe is currently in a flood-rich period from a long-term perspective. Here we analyse how recent decades compare with the flood history of Europe, using a new database composed of more than 100 high-resolution (sub-annual) historical flood series based on documentary evidence covering all major regions of Europe. We show that the past three decades were among the most flood-rich periods in Europe in the past 500 years, and that this period differs from other flood-rich periods in terms of its extent, air temperatures and flood seasonality. We identified nine flood-rich periods and associated regions. Among the periods richest in floods are 1560–1580 (western and central Europe), 1760–1800 (most of Europe), 1840–1870 (western and southern Europe) and 1990–2016 (western and central Europe). In most parts of Europe, previous flood-rich periods occurred during cooler-than-usual phases, but the current flood-rich period has been much warmer. Flood seasonality is also more pronounced in the recent period. For example, during previous flood and interflood periods, 41 per cent and 42 per cent of central European floods occurred in summer, respectively, compared with 55 per cent of floods in the recent period. The exceptional nature of the present-day flood-rich period calls for process-based tools for flood-risk assessment that capture the physical mechanisms involved, and management strategies that can incorporate the recent changes in risk. Analysis of thousands of historical documents recording floods in Europe shows that flooding characteristics in recent decades are unlike those of previous centuries.
136 citations
TL;DR: The results showed that the implementation of dynamic LULC change into the SWAT model could be adopted as a planning tool to manageLULC change of the Anzali wetland catchment in the future.
115 citations
References
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TL;DR: Intensive forestry practiced within subtropical forests resulted in the highest rates of forest change globally, and boreal forest loss due largely to fire and forestry was second to that in the tropics in absolute and proportional terms.
Abstract: Quantification of global forest change has been lacking despite the recognized importance of forest ecosystem services. In this study, Earth observation satellite data were used to map global forest loss (2.3 million square kilometers) and gain (0.8 million square kilometers) from 2000 to 2012 at a spatial resolution of 30 meters. The tropics were the only climate domain to exhibit a trend, with forest loss increasing by 2101 square kilometers per year. Brazil's well-documented reduction in deforestation was offset by increasing forest loss in Indonesia, Malaysia, Paraguay, Bolivia, Zambia, Angola, and elsewhere. Intensive forestry practiced within subtropical forests resulted in the highest rates of forest change globally. Boreal forest loss due largely to fire and forestry was second to that in the tropics in absolute and proportional terms. These results depict a globally consistent and locally relevant record of forest change.
7,890 citations
TL;DR: In this paper, the authors focus on the use of paired catchment studies for determining the changes in water yield at various time scales resulting from permanent changes in vegetation and highlight the potential underestimation of water yield changes if regrowth experiments are used to predict the likely impact of permanent alterations to a catchment's vegetation.
1,384 citations
TL;DR: In this paper, the authors evaluated trends in streamflow for 395 climate-sensitive streamgaging stations in the conterminous United States using the nonparametric Mann-Kendall test.
Abstract: Secular trends in streamflow are evaluated for 395 climate-sensitive streamgaging stations in the conterminous United States using the non-parametric Mann-Kendall test. Trends are calculated for selected quantiles ofdischarge, from the Oth to the 100th percentile, to evaluate differences between low-, medium-, and high-flow regimes during the twentieth century. Two general patterns emerge; trends are most prevalent in the an nual minimum (Qo) to median (Qso) flow categories and least prevalent in the annual maximum (QIOO) category; and, at all but the highest quantiles, streamflow has increased across broad sec tions of the United States. Decreases appear only in parts of the Pacific Northwest and the Southeast. Systematic patterns are less apparent in the QlOo flow. Hydrologically, these results indicate that the conterminous U.S. is getting wetter, but less extreme.
759 citations
TL;DR: In this article, the authors present an historical perspective of the controversy concerning the hydrological impact of forests, and show how a mostly romantic and emotional confrontation finally evolved into a scientific debate.
712 citations
TL;DR: In many agricultural regions, more than 80% of some catchment basins may be drained by surface ditches and subsurface drain pipes (tiles), which has significant effects on channel morphology, instream habitats for aquatic organisms, floodplain and riparian connectivity, sediment dynamics, and nutrient cycling as discussed by the authors.
Abstract: The extensive development of surface and subsurface drainage systems to facilitate agricultural production throughout North America has significantly altered the hydrology of landscapes compared to historical conditions. Drainage has transformed nutrient and hydrologic dynamics, structure, function, quantity, and configuration of stream and wetland ecosystems. In many agricultural regions, more than 80% of some catchment basins may be drained by surface ditches and subsurface drain pipes (tiles). Natural channels have been straightened and deepened for surface drainage ditches with significant effects on channel morphology, instream habitats for aquatic organisms, floodplain and riparian connectivity, sediment dynamics, and nutrient cycling. The connection of formerly isolated wetland basins to extensive networks of surface drainage and the construction of main channel ditches through millions of acres of formerly low-lying marsh or wet prairie, where no defined channel may have previously existed, have r...
596 citations