Réf. Scheurer & al. 2009 - A

Référence bibliographique complète

SCHEURER, K., ALEWELL, C., BÄNNINGER, D., BURKHARDT-HOLM, P. 2009. Climate and land-use changes affecting river sediment and brown trout in alpine countries—a review. Environmental Science and Pollution Research, 16, 232-242.

Abstract:
Background, aim, and scope
Catch decline of freshwater fish has been recorded in several countries. Among the possible causes, habitat change is discussed. This article focuses on potentially increased levels of fine sediments going to rivers and their effects on gravel-spawning brown trout. Indications of increased erosion rates are evident from land-use change in agriculture, changes in forest management practices, and from climate change. The latter induces an increase in air and river water temperatures, reduction in permafrost, changes in snow dynamics and an increase in heavy rain events. As a result, an increase in river sediment is likely. Suspended sediment may affect fish health and behaviour directly. Furthermore, sediment loads may clog gravel beds impeding fish such as brown trout from spawning and reducing recruitment rates. To assess the potential impact on fine sediments, knowledge of brown trout reproductive needs and the effects of sediment on brown trout health were evaluated.

Approach We critically reviewed the literature and included results from ongoing studies to answer the following questions, focusing on recent decades and rivers in alpine countries.
– Have climate change and land-use change increased erosion and sediment loads in rivers?
– Do we have indications of an increase in riverbed clogging?
– Are there indications of direct or indirect effects on brown trout from increased suspended sediment concentrations in rivers or from an increase in riverbed clogging?

Results Rising air temperatures have led to more intensive precipitation in winter months, earlier snowmelt in spring, and rising snow lines and hence to increased erosion. Intensification of land use has supported erosion in lowland and prealpine areas in the second half of the twentieth century. In the Alps, however, reforestation of abandoned land at high altitudes might reduce the erosion risk while intensification on the lower, more easily accessible slopes increases erosion risk. Data from laboratory experiments show that suspended sediments affect the health and behaviour of fish when available in high amounts. Point measurements in large rivers indicate no common lethal threat and suspended sediment is rarely measured continuously in small rivers. However, effects on fish can be expected under environmentally relevant conditions. River bed clogging impairs the reproductive performance of gravel-spawning fish.

Discussion Overall, higher erosion and increased levels of fine sediment going into rivers are expected in future. Additionally, sediment loads in rivers are suspected to have considerably impaired gravel bed structure and brown trout spawning is impeded. Timing of discharge is put forward and is now more likely to affect brown trout spawning than in previous decades.

Conclusions Reports on riverbed clogging from changes in erosion and fine sediment deposition patterns, caused by climate change and land-use change are rare. This review identifies both a risk of increases in climate erosive forces and fine sediment loads in rivers of alpine countries. Increased river discharge and sediment loads in winter and early spring could be especially harmful for brown trout reproduction and development of young life stages.Recently published studies indicate a decline in trout reproduction from riverbed clogging in many rivers in lowlands and alpine regions. However, the multitude of factors in natural complex ecosystems makes it difficult to address a single causative factor.

Recommendations and perspectives Further investigations into the consequences of climate change and land-use change on river systems are needed. Small rivers, of high importance for the recruitment of gravel-spawning fish, are often neglected. Studies on river bed clogging are rare and the few existing studies are not comparable. Thus, there is a strong need for the development of methods to assess sediment input and river bed clogging. As well, studies on the effects to fish from suspended sediments and consequences of gravel beds clogging under natural conditions are urgently needed.

Mots-clés

Alpine region . Agriculture . Brown trout . Climate change . Clogging erosion . Fish health . Global change . Gravel-spawning . Hydrology . Land-use change . Precipitation . Reproduction . Rivers . Salmonids . Salmo trutta . Suspended sediment


Organismes / Contact

• Man-Society-Environment MGU, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland - patricia.holm@unibas.ch
• Institute of Environmental Geosciences, University of Basel, Bernoullistrasse 30, 4056 Basel, Switzerland


(1) - Paramètre(s) atmosphérique(s) modifié(s)
(2) - Elément(s) du milieu impacté(s)
(3) - Type(s) d'aléa impacté(s)
(3) - Sous-type(s) d'aléa
Temperature, Precipitation Erosion (river sediment: suspended particles and bedload)    

Pays / Zone
Massif / Secteur
Site(s) d'étude
Exposition
Altitude
Période(s) d'observation
Alpine countries          

(1) - Modifications des paramètres atmosphériques
Reconstitutions
 
Observations

Changes in air temperature:
Recent studies have shown that air temperature in the alpine regions is changing more rapidly than in other regions of the northern hemisphere and the global average (Lebensministerium 2003; Beniston 2006; Hari et al. 2006). From data analyses of twelve stations in Switzerland in the period 1864–2000, Begert et al. (2005) found a rise in temperature by 1.1°C and 0.6°C per century in northern and southern side of the Alps, respectively, and the warming occurred mainly during autumn and winter months. However, more recently (1978–2002), changes in air temperatures occurred in spring and summer at lower altitude stations (<700 m a.s.l.; Hari et al. 2006).

Changes in snow dynamics:
Rising air temperature and especially the increasing number of days with air temperatures above zero influence the occurrence of snowfall and time of snowmelt (Birsan et al. 2005), resulting in a rising snow line.

Effects of changes in precipitation patterns:
The changes in precipitation patterns are different on the northern and the southern part of the alpine rim. While a significant negative trend for total annual precipitation over the last two centuries in the southern part of the Alps has been shown, the average trend was positive for the northern alpine region, particularly in winter and spring (Brunetti et al. 2006). An increase in amount and duration of torrential rain events, especially in winter and autumn months, during the last three to five decades has been demonstrated mainly for the northern alpine region while there is a slight positive, non-significant trend for the southern parts (Schmidli and Frei 2005; Fuhrer et al. 2006; Diodato and Mariani 2007). In the south, these extreme events alternate with increasing dry periods in autumn and spring (Schmidli and Frei 2005). In the north, the increase in precipitation in winter is also caused by extended long rain events (Schmidli and Frei 2005).

Modélisations
 
Hypothèses
 

Informations complémentaires (données utilisées, méthode, scénarios, etc.)
Bibliographic review

(2) - Effets du changement climatique sur le milieu naturel
Reconstitutions
 
Observations

Background, aim, and scope:
[...] One potential cause of increased erosion and sediment loads in rivers could be increased temperatures, altered precipitation patterns (strength, timing and altitude), changes in snow cover and seasonal snow melting caused by climate change (IPCC 2007; Fuhrer et al. 2006; Beniston 2006). These may have led to increased river runoff, especially in winter and in spring, and altered seasonal and regional sediment load and riverbed clogging patterns.

A second driver of potentially increased erosion rates is change in land use, which affects natural habitats and stream morphology significantly. The combination of more intensive rainfall and changes in land use have generally led to increased erosion over the last decades (FAL 2001; Gentile and Werner 2004). In addition, rivers have been modified in the twentieth century for flood protection, bed stabilization and hydropower dams and have influenced flow velocity and gravel movement: these factors together have supported riverbed clogging.

Consequences of changes in air temperature:
[...] Rising air temperature is reflected in coherent rise in water temperatures (up to +1.1°C) in streams both in the lowlands and in the foothills of the Alps, but the changes are less obvious in alpine streams influenced by glaciers and/or hydropower stations (Hari et al. 2006; Matulla et al. 2007). Rising water temperature has shifted the thermal habitat for fish communities upwards up to 130 m (Hari et al. 2006; Matulla et al. 2007) and might affect fish health and reproduction. While temperature will have no direct effect on river sediment loads, indirect effects can be expected from changed precipitation patterns, a decline in permafrost, snow melting and rising snow lines with associated potential increases in soil erosion.

Changes in snow dynamics:
Rising air temperature and especially the increasing number of days with air temperatures above zero influence the occurrence of snowfall and time of snowmelt (Birsan et al. 2005), resulting in a rising snow line. Changes in snowmelt are considered to be mainly critical for altitudes between 500–800 (in winter) and 1,000–1,500 m a.s.l. (in spring; Wielke et al. 2004). Snow depths decreased in the late 1980s and 1990s at low elevations (<1,000–1,300 m a.s.l. in Jan–Feb; Laternser and Schneebeli 2003; Beniston 2006), but increased at high elevations (>2,000 m a.s.l.; Beniston 2006). At the same time snow melting is reported to occur earlier in spring due to rising temperatures but with no obvious shift of snow accumulation in autumn (Laternser and Schneebeli 2003).

Effects of changes in precipitation patterns:
Torrential rain is widely believed to considerably contribute to sediment erosion (Summer 1989; Acornley and Sear 1999; Fraser et al. 1999; Descroix and Gautier 2002). Additionally, both droughts followed by heavy rain events and long consecutive rain events on already saturated soil can trigger erosion; the latter at an even higher extent than single day heavy rainfall events (Prasuhn 2003).

Trends in fluvial hydrology:
Many studies pointed to the sensitivity of the alpine hydrological system to climate change (Weingartner et al. 2003; Jasper et al. 2004; Birsan et al. 2005; Horton et al. 2006). A comprehensive trend analysis of the runoff regimes of 48 undisturbed catchment areas in Switzerland showed that the annual runoff increased in the last century (Birsan et al. 2005). This was mainly due to a higher discharge in winter (mainly high flows), but also increased runoff for autumn and spring (moderate and low flows) since 1960. In another study, Santschi (2003) analyzed specifically the winter discharge in 41 river basins with respect to gravel bed movements and destruction of the upper layer of the riverbed. For alpine rivers and rivers south of the Alps, a critical increase in winter discharge was not evident with the available data (Santschi 2003). In the Swiss Plateau and the Jura, however, Santschi (2003) found an increase of high flows in winter for 35% of the rivers after 1960. These trends of increased winter discharge are suspected to lead to downstream sediment transport and scouring of riverbed and therefore are assumed to disturb fish reproduction.

Effects of land-use and climate change on sediment yields in rivers:
Long-term trends in sediment yields have been mainly evaluated for larger Alpine rivers. The sediment yield in the Danube catchment has increased by 30–50% in the period 1950–1980 and to some degree in the river Lech after 1965 (Summer et al. 1994; Walling 1997). This trend is assumed to be caused by changed agricultural management and changed precipitation patterns, respectively. Decreasing trends were reported in areas of reforestation in the French Alps (Descroix and Gautier 2002; Piégay et al. 2004; Liébault et al. 2005) or beneath hydropower plants (Habersack 1996; Weiss 1996; Walling 1997). Increasing trends in suspended sediment concentrations for peak flows have also been documented in some rivers (e.g. in the Danube by a factor up to 2; Summer et al. 1994), whereas in many cases no clear trend could be found (Zobrist et al. 2004). Higher sediment discharges are usually related to high flows during snowmelt or heavy rainfall in spring, summer and autumn (Lenzi et al. 2003; Margreth 2006; Asselman et al. 2003). Thus, the greatest transport of fine sediments within the stream occurs in relatively short time periods (Summer et al. 1994; Hamm et al. 1996). Suspended sediment may only reflect the smallest fraction of fine sediments (silt and clay) transported downstream. (Heywood and Walling 2007) concluded that the majority of sediment accumulating in the riverbed is transported downstream with the fine-grained bed load.

Reservoir hydropower plants and other dam construction affect the magnitude and timing of hydrological regime and downstream sediment transport substantially, which often results in gravel deficiency downstream (Habersack 1996; Weiss 1996; Walling 1997; Beyer Portner 1998). [...]

Seasonal changes in river discharge due to changed precipitation patterns and earlier snowmelt may have changed the timing of the sediment transport downstream.

Modélisations

Changes in snow dynamics:
With the projection of further warming, the duration of snow cover is predicted to be shortened by more than 100 days with earlier snowmelt in spring (Jasper et al. 2004; Beniston 2006; Horton et al. 2006).

Trends in fluvial hydrology:
With the expected increase in temperature, some studies predict an advance of the peak flows in spring by 0.5–2 month/century for the north side of the Alps and up to 1 month/century on the south side of the Alps (Jasper et al. 2004; Horton et al. 2006). However, the projected runoff peaks will be substantially lower (20–50%) than the present peak flows (Jasper et al. 2004).

Effects of land-use and climate change on sediment yields in rivers:
Looking at combined future climate and land-use change scenarios Asselman et al. (2003) calculated an increase in the future annual sediment supply of 250% for the alpine Rhine catchment.

Hypothèses

Changes in snow dynamics:
A permanent snow cover in winter protects the soil from freezing, which is important for snowmelt infiltration and runoff, respectively (Stähli et al. 2001; Bayard et al. 2005). Thus, higher levels of rainfall and changes in freezing/thawing cycles can be expected to increase soil erosion and mass movement because of sparse or no vegetation cover at low elevations in winter and in early spring.

Effects of land-use and climate change on sediment yields in rivers:
Seasonal changes in river discharge due to changed precipitation patterns and earlier snowmelt may have changed the timing of the sediment transport downstream. Sediment transport downstream alternating with sediment deposition on gravel beds can now be expected to occur also in winter and earlier in spring and hence affecting trout spawning and incubation.


Sensibilité du milieu à des paramètres climatiques
Informations complémentaires (données utilisées, méthode, scénarios, etc.)

Snow dynamics:
A permanent snow cover in winter protects the soil from freezing, which is important for snowmelt infiltration and runoff, respectively (Stähli et al. 2001; Bayard et al. 2005).

Effects of changes in precipitation patterns:
Torrential rain is widely believed to considerably contribute to sediment erosion (Summer 1989; Acornley and Sear 1999; Fraser et al. 1999; Descroix and Gautier 2002). Additionally, both droughts followed by heavy rain events and long consecutive rain events on already saturated soil can trigger erosion; the latter at an even higher extent than single day heavy rainfall events (Prasuhn 2003).

[See also 3.2 Effects of land-use change on soil erosion in the study...]

Bibliographic review


(3) - Effets du changement climatique sur l'aléa
Reconstitutions
 
Observations
 
Modélisations
 
Hypothèses
 

Paramètre de l'aléa
Sensibilité des paramètres de l'aléa à des paramètres climatiques
Informations complémentaires (données utilisées, méthode, scénarios, etc.)
 

 


(4) - Remarques générales

Background, aim, and scope:
[See references in the study] Freshwater fish catches have been declining dramatically in the last decades in many countries. In Switzerland, the reported trout catch decreased in 85% of the investigated rivers. In some rivers, catches have been declining by up to 10% per year since the early 1980s. A decline in fish health was also observed with this trend and together have been the reason to launch a nationwide interdisciplinary research project called ‘Fischnetz’ in 1998. Three main causes for the decrease in brown trout catches were identified: (1) fisheries management; (2) PKD (proliferative kidney disease); and (3) poor habitat morphology and water quality. Among the poor habitat morphology, the hypothesis of increased soil erosion and subsequent sediments going into rivers was discussed. However, particularly due to insufficient data availability, the linkage to riverbed clogging (reduction in riverbed interstitial flow from sediment deposition) and direct or indirect impairment on fish health by suspended sediments could not be evaluated. [...] The purpose of this review is to study changes in erosion and levels of fine sediment (sediments with a diameter <2 mm) going into alpine rivers from land use and climate change and assess the effects on brown trout reproductive performance and health.


(5) - Syntèses et préconisations

Conclusions:
An increase in climate erosive forces has been demonstrated for northern and southern Alps. High discharges increased in winter months and reach levels for gravel bed movement critical for different reproduction stages of brown trout in some lowland and pre-alpine streams north of the Alps. For alpine rivers and rivers south of the Alps data is scarce and a critical increase was not evident. In both regions, climate models also predict an advance of the peak flows in spring by 1–2 months, which could overlap the time of advanced fry emergence.

The combination of land-use and climate change has led to increased erosion in the lowland, pre-alpine and alpine regions at least until the 1990s. In the Alps, the more recent development is still in discussion. Erosion has increased in some areas due to abandonment (remote regions) or use intensification (accessible regions) of land and due to climate change effects. Contrasting effects are forest regrowth in abandoned areas and further reclamation by trees of higher slopes due to climate warming. Overall effects seem to result in an increase of sediment loads in some larger river catchments and are expected to increase in future.

As high flows now also occur in autumn and winter months and earlier in spring, transport and sedimentation of fine sediment during reproduction and embryo development are expected. Strong discharges cause gravel movements, leading to egg scouring, injury and displacement of young fish. Moderate discharge events result in fine sediment infiltration into redds reducing the interstitial flow, and hence, oxygen supply, with detrimental consequences for eggs and embryos. Clay particles attached at the egg surface are supposed to impair gas exchange and reduce embryo viability, and suspended sediments affect brown trout health and behaviour depending on concentrations, but also on the size, form and quality of the particles. With the lack of long-term trend data for sediment going into rivers, sediments suspended in rivers and riverbed clogging, a direct correlation with fish population or catch data is not possible at the current state of knowledge. Recently published studies indicate a decline in trout reproduction from riverbed clogging in many rivers in lowlands and alpine regions. However, the multitude of factors in natural complex ecosystems makes it difficult to address a single causative factor. As a consequence, it has to be elucidated whether riverbed clogging and sediment concentrations present can impair fish reproduction, health and behaviour.

Recommendations and perspectives:
Sediment entering rivers from erosion has been recognised by experts as a problem and several initiatives have been taken including measures to reduce these stress factors in surface water systems (Alpenkonvention 1991; Fischnetz+ 2007). These initiatives need to be implemented. From the scientific point of view, erosion trends in the Alps are not clearly understood and further research is necessary in this field. Investigations into the consequences of climate and land-use change on river systems, such as sediment going into rivers, transport and clogging processes are therefore needed. Especially small rivers, serving as recruitment sites of gravel-spawning fish, are often neglected. There is also a strong need to develop methods for sound data collection on sediment input and river bed clogging. Without the latter, it will not be possible to draw consequences on scientific progress and mitigation measures. Studies on the effects of suspended sediments on fish health under environmentally realistic conditions, especially taking origin, size and shape of the particles into consideration should be carried out. Furthermore, the consequences of gravel bed clogging for reproduction of our native gravel-spawning fish, such as trout, grayling and charr are urgently needed to be studied. There is a lack of information on the linkage between riverbed clogging and interstitial gas exchange in most alpine field studies and this area should be considered in future research. In general, it is necessary to understand the abiotic–biotic interaction in aquatic ecosystems and provide suggestions for more advanced water quality guidelines (Bilotta and Brazier 2008).

Références citées :

Acornley RM, Sear DA (1999) Sediment transport and siltation of brown trout (Salmo trutta L.) spawning gravels in chalk streams. Hydrol Process 13:447–458

Alpenkonvention (1991) www.alpenkonvention.org

Asselman NEM, Middelkoop H, van Dijk PM (2003) The impact of changes in climate and land use on soil erosion, transport and deposition of suspended sediment in the river Rhine. Hydrol Process 17:3225–3244

Bayard D, Stähli M, Parriaux A, Flühler H (2005) The influence of seasonally frozen soil on the snowmelt runoff at two Alpine sites in southern Switzerland. J Hydrol 309:66–84

Begert M, Schlegel T, Kirchhofer W (2005) Homogeneous temperature and precipitation series of Switzerland from 1864 to 2000. Int J Climatol 25:65–80

Beniston M (2006) Mountain weather and climate: a general overview and a focus on climatic change in the Alps. Hydrobiologia 562:3–16

Beyer Portner N (1998) Erosion des bassins versant alpines suisses par ruissellement de surface. PhD thesis, EPFL, Lausanne, pp 230

Bilotta GS, Brazier RE (2008) Understanding the influence of suspended solids on water quality and aquatic biota. Water Res 42(12):2849–2861

Brunetti M, Maugeri M, Nanni T, Auer I, Bohm R, Schoner W (2006) Precipitation variability and changes in the greater alpine region over the 1800–2003 period. J. Geophys. Res. [Atmos.] 111: D11107, doi:10.1029/2005JD006674

Birsan MV, Molnar P, Burlando P, Pfaundler M (2005) Streamflow trends in Switzerland. J Hydrol 314:312–329

Descroix L, Gautier E (2002) Water erosion in the southern French Alps: climatic and human mechanisms. Catena 50:53–85

Diodato N, Mariani L (2007) Testing a climate erosive forcing model in the Po River Basin. Climate Res 33:195–205

FAL (2001) Evaluation der Ökomassnahmen. Phosphorbelastung der Oberflächengewässer durch Bodenerosion. FAL, Zürich-Reckenholz, p 37

Fischnetz+ (2007) Gesunde Fische in unseren Fliessgewässern. 10-Punkte-Plan. EAWAG, Bundesamt für Umwelt, Bern, p 24

Fraser AI, Harrod TR, Haygarth PM (1999) The effect of rainfall intensity on soil erosion and particulate phosphorus transfer from arable soils. Water Sci Technol 39:41–45

Fuhrer J, Beniston M, Fischlin A, Frei C, Goyette S, Jasper K, Pfister C (2006) Climate risks and their impact on agriculture and forests in Switzerland. Clim Change 79:79–102

Gentile AR, Werner B (2004) Gone with the wind, gone into water—soil erosion in Europe—pressures, state and impacts. Local Land& Soil News 10/11:6–9

Habersack H (1996) Lack and surplus of sediments being transported by river systems. In: Erosion and sediment yield: global and regional perspectives. IAHS 236:565–573

Hamm A, Glassmann M, Liepelt A (1996) Transport of particulate matter in an alpine river (river Salzach) and its importance for river ecology. Arch Hydrobiol 47:507–513

Hari RE, Livingstone DM, Siber R, Burkhardt-Holm P, Güttinger H (2006) Consequences of climatic change for water temperature and brown trout populations in alpine rivers and streams. Glob Change Biol 12:10–26

Heywood MJT, Walling DE (2007) The sedimentation of salmonid spawning gravels in the Hampshire Avon catchment, UK: implications for the dissolved oxygen content of intragravel water and embryo survival. Hydrol Process 21:770–788

Horton P, Schaefli B, Mezghani A, Hingray B, Musy A (2006) Assessment of climate-change impacts on alpine discharge regimes with climate model uncertainty. Hydrol Process 20:2091–2109

Ingendahl D (2001) Dissolved oxygen concentration and emergence of sea trout fry from natural redds in tributaries of the River Rhine. J Fish Biol 58:325–341

IPCC (2007) Climate change 2007: impacts, adaptation and vulnerability. In: Parry ML, Canziani OF, Palutikof JP, van der Linden PJ, Hanson CE (eds) Contribution of working group II to the fourth assessment report of the IPCC. Cambridge University Press, Cambridge, UK, p 976

Jasper K, Calanca P, Gyalistras D, Fuhrer J (2004) Differential impacts of climate change on the hydrology of two alpine river basins. Climate Res 26:113–129

Laternser M, Schneebeli M (2003) Long-term snow climate trends of the Swiss Alps (1931–99). Int J Climatol 23:733–750

Lebensministerium (2003) Auswirkungen von Klimaänderungen auf die Tierwelt—derzeitiger Wissensstand, fokussiert auf den Alpenraum und Österreich. Institut für Meteorologie und Physik und BOKU, Wien, p 141

Lenzi MA, Mao L, Comiti F (2003) Interannual variation of suspended sediment load and sediment yield in an alpine catchment. Hydrol Sci J 48:899–915

Liébault F, Gomez B, Page M, Marden M, Peacock D, Richard D, Trotter CM (2005) Land-use change, sediment production and channel response in upland regions. River Res Applic 21:739–756

Margreth S (2006) Partikelfluss und Sedimentbildung in Oberengadiner Seen. MSc thesis, University of Zurich, Zurich, p 56

Matulla C, Schmutz S, Melcher A, Gerersdorfer T, Haas P (2007) Assessing the impact of a downscaled climate change simulation on the fish fauna in an Inner-Alpine River. Int J Biometerol 52:127–137

Piégay H, Walling DE, Landon N, He QP, Liébault F, Petiot R (2004) Contemporary changes in sediment yield in an alpine mountain basin due to afforestation (the upper Drome in France). Catena 55:183–212

Prasuhn V (2003) Zunahme der Bodenerosion von Ackerflächen im Winterhalbjahr? In: Mitteilungen DBG, pp 789–790

Santschi D (2003) Zeitliche Veränderung der winterlichen Abflusscharakteristik schweizerischer Fliessgewässer. MSc thesis, University of Bern, Bern, p 109

Schmidli J, Frei C (2005) Trends of heavy precipitation and wet and dry spells in Switzerland during the 20th century. Int J Climatol 25:753–771

Stähli M, Nyberg L, Mellander PE, Jansson PE, Bishop KH (2001) Soil frost effects on soil water and runoff dynamics along a boreal transect: 2. Simulations. Hydrol Process 15:927–941

Summer W (ed) (1989) Umfassende Betrachtung der Erosions- und Sedimentationsproblematik. Wiener Mitteilungen Nr. 86, Wien

Summer W, Zhang W, Stritzinger W (1994) Consequences of human impacts on the sediment transport process. Z f Kulturtechnik und Landentwicklung 35:382–389

Summer W, Klaghofer E, Hintersteiner K (1996) Trends in soil erosion and sediment yield in the alpine basin of the Austrian Danube. In: Erosion and Sediment Yield. IAHS. 236:473–479

Walling DE (1997) The response of sediment yields to environmental change. In: Human Impact on Erosion and Sedimentation. IAHS 245:77–89

Walling DE, Collins AL, McMellin GK (2003) A reconnaissance survey of the source of interstitial fine sediment recovered from salmonid spawning gravels in England and Wales. Hydrobiologia 497:91–108

Weingartner R, Barben M, Spreafico M (2003) Floods in mountain areas—an overview based on examples from Switzerland. J Hydrol 282:10–24

Weiss FH (1996) Sediment monitoring, long-term loads, balances and management strategies in southern Bavaria. In: Erosion and sediment yield: Global and regional perspectives. IAHS 236:575–582

Wielke LM, Haimberger L, Hantel M (2004) Snow cover duration in Switzerland compared to Austria. Meteorol Z 13:13–17

Zobrist J, Sigg L, Schönenberger U (2004) NADUF—Thematische Auswertung der Messresultate 1974–1998. Schriftenreihe Nr. 18. EAWAG, Dübendorf, p 125