Maximum River Discharge Research Articles

Deciphering the Role of Total Water Storage Anomalies in Mediating Regional Flooding

AbstractRegional floods result from various flood generation mechanisms. Traditional analyses mainly link flooding to extreme rainfall, with limited input from soil moisture. Total water storage (TWS) is a holistic measure of basin wetness, including additional storage components from surface water, snow, and groundwater. Utilizing a new 5‐day Gravity Recovery and Climate Experiment and its Follow On (GRACE(‐FO)) data set, we investigated the linkage between short‐term TWS anomaly (TWSA) and regional flooding. The 5‐day TWSA solutions revealed flood signals missed by monthly TWSA solutions. Global basins exhibit distinct storage‐discharge co‐evolution patterns, offering new insights into flood mechanisms and propensity. Our bivariate event analyses show the annual maximum river discharges co‐occur more often with the TWSA maxima than with precipitation in many basins. Further analyses revealed TWSA's time‐lagged effect on river discharge, particularly in basins susceptible to floods triggered by saturation‐excess runoff. The 5‐day TWSA provides a new source of information for enhancing global flood preparedness.

Climate Change and Flood Vulnerability Analysis in the Narayani River of Nepal

Flood disasters annually devastate livelihoods, particularly during the monsoon season, with no apparent reduction in impacts in low-lying regions of developing countries like Nepal. Given the increasing effects of climate change globally, this study aims to assess climate change effects and biophysical vulnerability of riverine communities to floods in the Narayani River of Nepal, elucidating the interrelationship between these phenomena. This paper presents an analysis of trends and extreme events of climatological variables, such as temperature, precipitation, and daily river discharge and hazard mapping and risk assessments in the river stretch of two Village Development Committees (VDCs) in the country’s inner Terai region of Nawalparasi district for different return-period floods, with the aid of the HEC-RAS (Hydrologic Engineering Centre’s River Analysis System) and HEC-GeoRAS. A long-term climatological data was collected from the Department of Hydrology and Meteorology, Kathmandu, and the analysis was performed using statistical softwares, SigmaStat, and SigmaPlot. In addition, flood conditions representing 2, and 100-year periods were determined using Gumbel’s distribution. The study revealed a narrowing temperature range, with increasing minimum temperatures and decreasing maximum temperatures, precipitation, and river discharge. However, there was a notable increase in extreme events. The hazard mapping indicated the people’s vulnerability to inundation and soil erosion along the low-lying riverbanks. The findings underscore the necessity for reliable technological and socio-economic vulnerability mapping to provide early warnings to at-risk populations. This paper argues that unplanned and mismanaged settlements in riverine areas may lead to population displacements, creating environmental refugees.

What is happening with frequency and occurrence of the maximum river discharges in Bosnia and Herzegovina?

In this study, we explored the frequency and occurrence rate of maximum river discharges in the Una and Sana rivers, to understand hydrological variations amidst climate change. We categorized maximum discharges into severe (Una River M1 > 98.2 m3/s; Sana River M1 > 118.2 m3/s) and extreme (Una River, M2, > 123.4 m3/s; Sana River M2 > 246.4 m3/s) events, and identified trends in these events, crucial for assessing environmental impacts. Our findings reveal a nuanced pattern: both rivers experience an increase in severe events from 58 to 55 and 56 to 54 days return period respectively, indicating complex hydrological dynamics. The trends underscore the significant shifts in annual event occurrences, the evolving nature of river systems and underscore the necessity for adaptive management strategies.

A high‐resolution inter‐annual framework for exploring hydrological drivers of large wood dynamics

AbstractRivers with alluvial bars store more wood than those without, supplied through channel shifting. However, wood dynamics (arrival or new deposits, departure or entrainment, and stable or immobile pieces) can vary substantially over time in response to critical hydrological drivers that are largely unknown. To evaluate them, we studied the dynamics of large wood pieces and logjams along a 12‐km reach of the lower Allier River using six series of aerial images of variable resolution acquired between 2009 and 2020, during which maximum river discharge fluctuated around the dominant flood discharge (Q1.5) that is potentially the bankfull discharge along this well‐preserved not incised reach. Individual wood departure was best correlated with water levels exceeding dominant flood discharge. The duration of the highest magnitude flood was best correlated with wood depositions, with shorter floods resulting in a higher number of deposits. Finally, most of the wood remained stable when river discharge did not exceed 60% of Q1.5 over a long period of time. Changes in inter‐annual wood budget (reach‐scale) depend on the duration over which discharge exceeded 60% of Q1.5. Hydrological conditions driving jam build‐up and removal were similar to those controlling individual wood piece dynamics. The results suggest that specific hydrological conditions influence the dynamics of large wood and log jams in the Allier River. Understanding the dynamics of large wood and its impact on river morphology is fundamental for successful river management and habitat restoration initiatives.

Characterization of Extreme Rainfall and River Discharge over the Senegal River Basin from 1982 to 2021

Extreme hydroclimate events usually have harmful impacts of human activities and ecosystems. This study aims to assess trends and significant changes in rainfall and river flow over the Senegal River Basin (SRB) and its upper basin during the 1982–2021 period. Eight hydroclimate indices, namely maximum river discharge (QMAX), standardized flow index, mean daily rainfall intensity index (SDII), maximum 5-day consecutive rainfall (RX5DAY), annual rainfall exceeding the 95th percentile (R95P), annual rainfall exceeding the 99th percentile (R99P), annual flows exceeding the 95th percentile (Q95P), and annual flows exceeding the 99th percentile (Q95P), were considered. The modified Mann–Kendall test (MMK) and Innovative Trend Analysis (ITA) were used to analyze trends, while standard normal homogeneity and Pettit’s tests were used to detect potential breakpoints in these trends. The results indicate an irregular precipitation pattern, with high values of extreme precipitation indices (R95p, R99p, SDII, and RX5DAY) reaching 25 mm, 50 mm, 20 mm/day, and 70 mm, respectively, in the southern part, whereas the northern part recorded low values varying around 5 mm, 10 mm, 5 mm/day, and 10 mm, respectively, for R95P, R99P, SDII, and RX5DAY. The interannual analysis revealed a significant increase (p-value < 5%) in the occurrences of heavy precipitation between 1982 and 2021, as manifested by a positive slope; a notable breakpoint emerged around the years 2006 and 2007, indicating a transition to a significantly wetter period starting from 2008. Concerning extreme flows, a significant increase was observed between 1982 and 2021 with Sen’s slopes for extreme flows (29.33 for Q95P, 37.49 for Q99P, and 38.55 for QMAX). This study provides a better understanding of and insights into past hydroclimate extremes and can serve as a foundation for future research in the field.

Assessment of the impact of climate change and flooding on bridges and surrounding area

Climate change has the potential to significantly impact transportation infrastructure performance. Bridges crossing rivers are designed to withstand a maximum flood level (design flood) considering the expected frequencies and magnitudes of floods in the area. The design flood level ensures the safety of the bridge without being damaged against historical flooding levels. However, flood magnitude and/or frequency are expected to increase in some regions due to climate change, and therefore, bridges may not be able to maintain their serviceability and safety, resulting in significant risk to users and economic losses. This problem is approached in this paper by investigating the effects of flooding and climate change on bridges crossing rivers and surrounding areas. The input of the proposed methodology is the river flow for various climate change scenarios as well as the topography and bridge characteristics. Flood frequency analysis is used to provide information about the magnitude and frequency of annual maximum river discharges under a changing climate. Afterwards, several risk assessment indicators are computed for the bridge and its surrounding area. In addition, stochastic Poisson process is integrated to account for the randomness of floods arrivals and to investigate stochastically the probability of exceeding the design flood level. The proposed methodology is illustrated with a case study in the United Kingdom. The results indicate that the risk of flooding, and associated consequences, would increase for the case study when considering more pessimistic climate change scenarios. Findings from this study can be used to inform decision making for improving bridges’ resilience.

Spatiotemporal analysis of 2020 monsoon floods and its impacts along selected reaches of the Padma River, Bangladesh

ABSTRACT The 2020 Monsoon Floods in Bangladesh had the longest duration since 1998 and affected 37% of the country. This study explored the impacts of flooding along selected reaches of the Padma River by analysing flood dynamics and bank erosion using Sentinel SAR-C and MSI image datasets, hydrologic, and field data. It involved mapping and validating the spatiotemporal distribution of flooding, erosion, and water turbulence. There were three phases of onset and recession of flooding between 1st July and 4th October, 2020. Image analysis showed that the highest floodwater extents during these phases were 14%, 20%, and 15% of the study area on 1st July, 6th August, and 23rd September, respectively. It was also found that a total of 92.8 km2 of riverbank area was eroded between 6th April and 7th November. The distribution of water turbulence and bank erosion showed concurrence in most parts while exceptions were also observed. From June to October 2020, Pearson’s correlation coefficients for monthly hydrologic data and erosion estimates were calculated to be (a) 0.791 between average river discharge and total eroded area, (b) 0.956 between maximum river discharge and total eroded area, (c) 0.741 between average water level and total eroded area, (d) 0.991 between average river discharge and average water level, (e) 0.519 between average water level and total rainfall, and (f) 0.484 between average water level and total rainfall. GIS analysis showed a total of 297 educational and healthcare facilities were flooded while 15 facilities were lost to bank erosion. A total of 489.75 km of road and 60.03 km2 of settlements were inundated.

O2 and CO2 Responses of the Synaptic Period to Under-Ice Phytoplankton Bloom in the Eutrophic Razdolnaya River Estuary of Amur Bay, the Sea of Japan

Hydrological conditions are an important factor for aquatic ecosystems. Their contribution to stimulating phytoplankton bloom in eutrophic estuaries is not quite clear. We present the results of an outbreak of a phytoplankton bloom event observed in the eutrophic Razdolnaya R. estuary in 2022 from January 22 to February 23, when the estuary was covered by ice. The bloom spreads over 21 km from the river mouth bar to upstream in the near-bottom layer below the halocline. The Chl-a concentration in the bloom area increased from 15 to 100 μg/L, and the dissolved oxygen concentration from 350 to 567 μmol/kg at a rate of 11 μmol/(kg day) over the study period, while the CO2 partial pressure was reduced to 108 µatm in the most oxygen-supersaturated waters. The Thalassiosira nordenskioeldii Cleve sea diatom was the dominant phytoplankton species in the bloom area. The opposite trend was observed near the boundary of the saline water wedge penetration over 29 km from the river mouth bar to upstream where the dissolved oxygen concentration decreased from 140 to 53 μmol/kg over a month, and partial pressure of CO2 reached 4454 μatm. We also present the results obtained in February 2016 before and after a snowfall, when the ability of PAR to penetrate through the ice was impeded by a layer of snow. After the snowfall, photosynthesis in the under-ice water stopped and the oxygen concentration decreased to almost zero due to the microbiological destruction of the phytoplankton biomass. As such, the main effect of phytoplankton bloom is the formation of superoxia/hypoxia (depending on the light conditions), during the period of maximum ice thickness and minimum river discharge. Thus, this study demonstrates that the eutrophication in the future could lead to unstable ecosystems and large synoptic variations of dissolved oxygen and CO2 partial pressure of the estuaries.

Characteristics of river discharge and its indirect effect on the tidal bore in the Qiantang River, China

Based on field data of river discharge, tide, tidal bore, and riverbed topography, the characteristics of river discharge, the effect of river discharge on riverbed erosion and sedimentation, and the feedback effect of riverbed erosion and sedimentation on the tide and tidal bore in the Qiantang River are analyzed. The results show that the inter-annual and seasonal variation of river discharge in the Qiantang River is noticeable, while the seasonal distribution of river discharge tends to be uniform after the construction of Xin'anjiang Reservoir. River discharge has a major effect on the erosion and sedimentation in the reach from Zhakou to Yanguan. There are laws of riverbed erosion in wet seasons and years and sedimentation in dry seasons and years. Relations in the Zhakou to Yanguan reach among the riverbed volume after the flood season, the mean and maximum river discharge during the flood season, and riverbed volume before the flood season are established. With the riverbed erosion from Zhakou to Yanguan, the low tide level decreases and the tidal range is amplified, and thus, the tidal bore is enhanced. The relation among tidal range, river discharge, and riverbed volume, as well as the one between the tidal bore height and tidal range is established on the basis of the field data. Furthermore, the variation range of tidal bores after the flood season is analyzed in wet and dry years. The indirect effect of the Xin'anjiang Reservoir on the height of the tidal bore is predicted and the mean height of the tidal bore from Zhakou to Yanguan decreases by 0.1–0.2 m.

Maximum Extreme Flow Estimations in Historical Hydrological Series under the Influence of Decadal Variations

The hypothesis of stationarity is a fundamental condition for the application of the statistical theory of extreme values, especially for climate variables. Decadal-scale fluctuations commonly affect maximum and minimum river discharges. Thus, the probability estimates of extreme events need to be considered to enable the selection of most appropriate time series. The current study proposed a methodology to detect the fluctuation of long wet and dry periods. The study was carried out at the gauging station 4C-001 in Pardo River, State of São Paulo, Brazil. The Spearman, Mann–Kendall and Pettitt’s non-parametric tests were also performed to verify the existence of a temporal trend in the maximum annual daily flows. The graph achieved from the Pettitt’s statistical variable allowed for the identification and separation of the longest dry period (1941 to 1975) and the longest wet period (1976 to 2011), decreasing again in 2012. Analysing the series separately, it was observed that both mean and standard deviation were higher than those corresponding to the dry period. The probable maximum flows for the corrected series showed estimates 10% higher than those estimated for the uncorrected historical series. The proposed methodology provided more realistic estimates for the extreme maximum flows.

Modeling Chinook Salmon Run Timing in the Gulkana River, Alaska Using Environmental Indices

AbstractEnvironmental data from the Gulkana River, in conjunction with in‐season Chinook Salmon Oncorhynchus tshawytscha passage numbers, are among the many tools used by the Alaska Department of Fish and Game to assess in‐season run strength and timing in the upper Copper River drainage. In this study, we refine the modeling of Chinook Salmon run timing by comparing methods based on linear, exponential, and polynomial regressions of marine and freshwater environmental indices for the Gulkana River stock. A range of temporal subsets and measurement techniques for coastal upwelling, air temperature, river discharge, and water temperature was analyzed in a stepwise process to update the in‐season forecast model. Ultimately, Gulkana River water temperature proved to be the most important variable in predicting run timing. A model considering daily maximum water temperature and river discharge can accurately estimate the proportion of the total run that swam upriver before July (pseudo‐R2 = 0.97), allowing for efficient Chinook Salmon fishery management through the latter portion of the run.

Applying non-parametric Bayesian networks to estimate maximum daily river discharge: potential and challenges

Abstract. Non-parametric Bayesian networks (NPBNs) are graphical tools for statistical inference widely used for reliability analysis and risk assessment and present several advantages, such as the embedded uncertainty quantification and limited computational time for the inference process. However, their implementation in hydrological studies is still scarce. Hence, to increase our understanding of their applicability and extend their use in hydrology, we explore the potential of NPBNs to reproduce catchment-scale hydrological dynamics. Long-term data from 240 river catchments with contrasting climates across the United States from the Catchment Attributes and Meteorology for Large-sample Studies (CAMELS) data set will be used as actual means to test the utility of NPBNs as descriptive models and to evaluate them as predictive models for maximum daily river discharge in any given month. We analyse the performance of three networks, one unsaturated (hereafter UN-1), one saturated (hereafter SN-1), both defined only by hydro-meteorological variables and their bivariate correlations, and one saturated network (hereafter SN-C), consisting of the SN-1 network and including physical catchments' attributes. The results indicate that the UN-1 network is suitable for catchments with a positive dependence between precipitation and discharge, while the SN-1 network can also reproduce discharge in catchments with negative dependence. The latter can reproduce statistical characteristics of discharge (tested via the Kolmogorov–Smirnov statistic) and have a Nash–Sutcliffe efficiency (NSE) ≥0.5 in ∼40 % of the catchments analysed, receiving precipitation mainly in winter and located in energy-limited regions at low to moderate elevation. Further, the SN-C network, based on similarity of the catchments, can reproduce discharge statistics in ∼10 % of the catchments analysed. We show that once a NPBN is defined, it is straightforward to infer discharge and to extend the network itself with additional variables, i.e. going from the SN-1 network to the SN-C network. However, the results also suggest considerable challenges in defining a suitable NPBN, particularly for predictions in ungauged basins. These are mainly due to the discrepancies in the timescale of the different physical processes generating discharge, the presence of a “memory” in the system, and the Gaussian-copula assumption used for modelling multivariate dependence.

Coupled three-dimensional modelling of groundwater-surface water interactions for management of seawater intrusion in Pingtung Plain, Taiwan

Study regionA coupled framework, linking subsurface flow and surface hydrodynamics, is developed and applied to a real-world case study of Pingtung coastal aquifer in southwest of Taiwan, in East Asia. Study focusFEFLOW is adopted to develop a 3-D variable density and transient groundwater model of the Pingtung shallow aquifer lying 250 m below mean sea level (MSL). This model is coupled with a 1-D river network model, comprised of the main river and its two tributaries, using MIKE 11 through the IFM MIKE 11 coupling interface. The model is capable of analysing the relationship between rainfall, surface water and groundwater recharge lag time. Also, the analysis of potential river inundation and maximum river discharge enable the model to choose the best location to apply artificial recharge as a management scenario to mitigate the effect of seawater intrusion (SWI). To the authors’ knowledge, the developed coupled model is the first detailed integrated framework analysing the interaction of surface and subsurface water, with the capability to contribute to the restoration, rehabilitation, and management of the river network. New hydrological insights for the regionThe rainfall ratio in the wet season to dry season is significant in this plain comparing with the rest of Taiwan. Also, southern Taiwan experiences the largest sea and river interaction, while Kaoping River playing as a pathway role for inland lead of seawater intrusion.

Interrelations of rainfall and morphometric characteristics in generating geological disasters of Kuranji watershed Padang city

The Kuranji watershed is one of the watersheds in the city of Padang, which is currently experiencing development due to rapid population growth. This has resulted in land conversion from areas that have vegetation to built areas such as settlements. This affects the balance of the Kuranji watershed ecosystem and can lead to geological disasters. Therefore an initial analysis is needed in the development of the Kuranji watershed in the future. This study aims to analyse the interrelation of rainfall and morphometric characteristics that have an impact on geological disasters. The data used are data of maximum rainfall and maximum river discharge in the Kuranji watershed from 2009 - 2018. DEM data (30x30) used to calculate morphometric aspects, consisting of linear aspects, area aspects and relief aspects. The calculation of these aspects is done by a Geographic Information System (GIS) approach using ArcGIS 10.6 software. The result shows that the Kuranji watershed has an area of 22469,55 ha with dendritic drainage patterns. The linear aspect reveals that it has 1894 rivers with a total length of 774,6 km. This aspect explains that with the many tributaries, the Kuranji watershed has the potential to cause flooding. Aspects of the area explain that the Kuranji watershed has an elongated shape, steep slope and causes a rapid and large run-off discharge. Drainage density is at medium level with a value of 3,45 (km/km2) which is close to the high category. The higher the drainage density the smaller the chance of water for infiltration and the greater the river discharge. The relief aspect explains that the Kuranji watershed has a height between 0-1860 meters above sea level. Relief ratio and gradient ratio have a value of 0,08. Gradient ratios with high values result in fast and swift flow of surface and river water flow. This has the potential for landslides, channel erosion and river wall erosion. High rainfall, extreme morphometric characteristics, causes the Kuranji watershed to have a great potential for geological disasters.

Impact of global warming on the conditions of the Siberian rivers discharge formation: significance of atmospheric transport

Impact of climate change on the Ob, Lena and Yenisei runoff is under discussion. Indexes of zonal, meridional and general circulation were used to assess the effect of changes in atmospheric circulation. Correlations between the indexes and surface air temperature, precipitation, atmospheric moisture content in the regions of catchment areas confirmed the influence of atmospheric transport in the cold part of the year. Assessment of the relationship between changes of climatic conditions in the catchment areas and interannual changes of river runoff parameters indicated that annual runoff increases and mostly is affected by increase of average annual precipitation. Frequency of maximum river discharges during climate warming is reduced.

The Effects of High River Discharges on the Morphodynamics of the Guadiana ebb-tidal delta

López-Ruiz, A.; Garel, E., and Ferreira, Ó., 2020. The effects of high river discharges on the morphodynamics of the Guadiana ebb-tidal delta. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 558-562. Coconut Creek (Florida), ISSN 0749-0208.This work analyses the role of high river discharges upon the morphodynamics of an ebb-tidal delta at a jettied inlet (the Guadiana river mouth, at the southern border between Portugal and Spain). The analysis is performed using a numerical model to simulate the effects of synthetic single high river discharge events with return periods ranging from 3 to 670 years. This model was calibrated and validated both for hydro- and morphodynamics. Results show that the area with mobile sediment over the delta varies strongly with the magnitude of the river discharge. Events peaking over 7,500 m3/s produce significant bathymetric variations at the delta, including scouring of the inlet channel, along with the offshore migration and volumetric growth of the outer shoal. Observations have indicated that the delta does not recover from these sudden morphological changes. However, the recent strong river flow regulation by dams has limited the maximum river discharges to 2,500 m3/s. Such vanishing of unusually high discharge events has affected both the short-term and long-term morphodynamics of the Guadiana ebb-tidal delta.

Temporal and spatial variability of beach litter in Mangaluru, India.

Monthly litter samples were collected from three major beaches in Mangaluru from 2011-2016. Fishing litter persisted at the beaches, resulting in higher abundances by number (59%) and weight (33.4%) relative to all litter in 2016. In addition to plastics, foam comprised 7.14-11.0% of total litter. Significant positive correlations were observed between the amount of plastic on the beaches and rainy days, rainfall, and river discharge. The maximum river discharge coincided with an increase in plastic items on the beach. Yearly quantities of plastic items (p < 0.01), plastic bags (p < 0.001), and plastic footwear (p < 0.05), on the beaches were significantly different indicating clean-up activities reduced the litter quantity. Changes in total beach litter revealed that Panambur Beach, a fishing boat landing centre was the least changed, and thus appropriate incentive-based management options for the resident fishermen could result in collection and elimination of litter.

Distribution Function of Maximum Discharge: Accounting for Probable Maximum Flood

The problem of obtaining the estimated statistical characteristics of maximum river discharge is considered, taking account of its maximally possible values. The solution method is based on reviewing the distributions bounded from above, i.e., having an upper bound. The extreme value of the discharge, characterized by the error in its determination, is used as the value of the upper limit. The calculated distribution function (probability curve) is derived using a Bayesian approach.

Application of Frequency Analysis on Peak River Discharge toward the Cumulative Floatable Litter Load at Log Boom Sungai Batu

The accumulation of floatable litter in the river is mainly influenced by the increasing number of human population, rapid urbanization and development which indirectly lead to the changes of hydrological processes in river discharge, decreasing the water quality and aesthetical value of the river. The main objective of this paper is to determine the cumulative floatable litter load captured at the log boom during the extreme events by using the Gumbel distribution method for frequency analysis in river discharge of Sungai Batu. The annual maximum river discharge for a period of 35 years (1982 to 2016) was used in Gumbel distribution method to obtain the discharge for different return period (2, 5, 10, 25, 50, 100, and 200). The result shows that the estimated discharge (103.17 m³/s) can estimate the cumulative floatable litter load (53267.27 kg/day) at 50 years return period. The R2 value obtained from non – linear regression analysis is 0.9986 indicate that Gumbel distribution is suitable to predict the expected discharge of the river. This study is very crucial for the related agencies in highlighting this environmental issues for their future references which can be used as a guidelines during the decision making process in making better improvement.

Winter climate signal in boreal clastic-biogenic varves: a comprehensive analysis of three varved records from 1890 to 1990 AD with meteorological and hydrological data from Eastern Finland

Clastic-biogenic varves are widely used for reconstructing past climate: in boreal environments, the accumulation of minerogenic clasts on the lake floor is generally considered a proxy for past variations in spring floods reflecting previous winter conditions. However, the physical mechanisms behind this winter climate sensitivity and the influence of catchment type on the varve formation are not fully investigated. Here, we present a winter climate record inferred from the clastic laminae of three lakes located on the region of fine-grained tills in Eastern Finland spanning from AD 1890 to 1990. The minerogenic varve data are compared with instrumental meteorological and hydrological time series in order to investigate the physical link between winter and spring climate and minerogenic matter accumulation. Our analyses reveal that the climate-catchment mechanisms operating in the region of fine-grained tills differ crucially from previously described climate catchment interactions on sand moraine-dominated catchments in Finland, where the maximum river discharge in spring controls the clastic lamina formation. However, in contrast to earlier boreal varve records from Central Finland, the clastic lamina formation in the studied region correlates negatively with spring temperatures and winter precipitation. This could be an artefact of varying catchment dynamics but also related to the regional climate. The lakes surrounded by catchments characterized by fine-grained tills are more sensitive to cold and dry winters. The differences in the sensitivity of varve characteristics to climate, highlights the importance of understanding the catchment dynamics in detail in order to better understand climatic forcing.