Effects of 66 years of water management and hydroclimatic change on the urban hydrology and water quality of the Panke catchment, Berlin, Germany.

Long-term records of combined stream flow and water chemistry can be an invaluable source of information on changes in the quantity and quality of water resources. To understand the effect of hydroclimate and water management on the heavily urbanized Panke catchment in Berlin, Germany, an extensive search, collation and digitization of historic data from various sources was undertaken. This integrated a unique 66-year spatially distributed record of stream water quality, a 21-year record of groundwater quality and a 31-year stream flow record. These data were analysed in the context of hydroclimatic variability, as well as the history and technological evolution of water resource management in the catchment. To contextualize the effect of droughts, "average" and wet years the Standard Precipitation Index (SPI) was applied. As upstream sites have been less regulated by human impacts, the flow regime is most sensitive to changes in hydroclimatic conditions, while downstream sites are more influenced by wastewater effluents, urban storm drains and inter-basin transfers for flood alleviation. However, at all sites, a general increase in maximum event discharge was observed until a recent drought, starting in 2018. In general, water quality in the catchment has gradually improved as a result of management change and increasingly effective wastewater treatment, though in some places legacy and/or contemporary urban and rural groundwater contamination may be affecting the stream. Hydroclimatic changes, particularly drought years can affect water quality classes, and alter the chemostatic/dynamic behaviour of catchment export patterns. These insights from the Panke catchment underline the importance of strategic adaptation and improvement of water treatment and water resource management in order to enhance the quality of urban water courses. It also demonstrates the importance of long-term integrated data sets.

Assessing runoff generation in riparian wetlands: monitoring groundwater-surface water dynamics at the micro-catchment scale.

Riparian wetlands (RW) are important variable source areas for runoff generation. They are usually characterised by a combination of groundwater exfiltration-which maintains saturated conditions in low-lying organic-rich soils-and direct precipitation. Both processes interact to generate overland flow as a dominant runoff process. The small-scale details of groundwater-surface water (GW-SW) interactions are usually not well understood in RW. Here, we report the results of a study from an experimental catchment in the Scottish Highlands where spatio-temporal runoff processes in RW were investigated using isotopes, alkalinity and hydrometric measurements. We focused on perennial micro-catchments within the RW and ephemeral zero-order channels draining peatland hollows and hummocks to better understand the heterogeneity in GW-SW interactions. The 12-month study period was dominated by the wettest winter (December/January) period on record. Runoff generation in the RW was strongly controlled by the local groundwater response to direct rainfall, but also the exfiltration of groundwater from upslope. This groundwater drainage is focused in the hollows in ephemeral and perennial drainage channels, but in wet conditions, as exfiltration rates increase, can affect hummocks as well. The hollows provide the dominant areas for mixing groundwater, soil water and direct rainfall to deliver water to the stream network as hollows "fill and spill" to increase connectivity. They also provide wet areas for evaporation which is evident in enriched isotope signatures in summer. Although there is some degree of heterogeneity in the extent to which groundwater influences specific micro-catchments, particularly under low flows, the overall isotopic response is quite similar, especially when the catchment is wet and this responses can explain the isotope signatures observed in the stream. In the future, more longitudinal studies of micro-catchments are needed to better explain the heterogeneity observed.

Exercise training improves physical function and fitness in long-term paediatric brain tumour survivors treated with cranial irradiation.

AIMS: We examined the efficacy of exercise training for improving physical functioning and cardiopulmonary fitness in survivors of paediatric brain tumours (BTs) treated with cranial irradiation. METHODS: We conducted a controlled clinical trial with crossover of exercise training versus no training in the community in either a group or combined group/home setting. A volunteer sample of 28 children treated with cranial irradiation for brain tumours completed training (mean age = 11.53 years; mean time since diagnosis = 5.25 years). end-points were physical functioning assessed by four subtests from the Bruininks-Oseretsky Test of motor performance (BOT-2) and pro-rated work rate from a cycle ergometer. Linear mixed modelling was used to evaluate time, training, training setting, and carryover effects. RESULTS: Adherence to training was 84%. Performance on the BOT-2 was below average for all assessments. However, training resulted in improvement in bilateral coordination (F (1, 30) = 6.59, p = 0.02), irrespective of training setting and improved performance was maintained even approximately 12°weeks after training had ended (F (1, 24) = 9.60, p = 0.005). Training resulted in increased pro-rated work rate for participants in the group training setting only (F (1, 25) = 4.57, p = 0.04) and these participants maintained their improved work rate approximately 12°weeks after training had ended (F (1, 20) = 8.38, p = 0.01). CONCLUSION: Exercise training improves physical functioning and fitness in paediatric BT survivors. Exercise interventions that ameliorate adverse physical effects and promote health in long-term survivors are highly recommended in this vulnerable population. (ClinicalTrials.gov, NCT01944761).

Stream water age distributions controlled by storage dynamics and nonlinear hydrologic connectivity: Modeling with high-resolution isotope data.

To assess the influence of storage dynamics and nonlinearities in hydrological connectivity on time-variant stream water ages, we used a new long-term record of daily isotope measurements in precipitation and streamflow to calibrate and test a parsimonious tracer-aided runoff model. This can track tracers and the ages of water fluxes through and between conceptual stores in steeper hillslopes, dynamically saturated riparian peatlands, and deeper groundwater; these represent the main landscape units involved in runoff generation. Storage volumes are largest in groundwater and on the hillslopes, though most dynamic mixing occurs in the smaller stores in riparian peat. Both streamflow and isotope variations are generally well captured by the model, and the simulated storage and tracer dynamics in the main landscape units are consistent with independent measurements. The model predicts that the average age of stream water is ∼1.8 years. On a daily basis, this varies between ∼1 month in storm events, when younger waters draining the hillslope and riparian peatland dominates, to around 4 years in dry periods when groundwater sustains flow. This variability reflects the integration of differently aged water fluxes from the main landscape units and their mixing in riparian wetlands. The connectivity between these spatial units varies in a nonlinear way with storage that depends upon precipitation characteristics and antecedent conditions. This, in turn, determines the spatial distribution of flow paths and the integration of their contrasting nonstationary ages. This approach is well suited for constraining process-based modeling in a range of northern temperate and boreal environments.

Storage dynamics in hydropedological units control hillslope connectivity, runoff generation, and the evolution of catchment transit time distributions.

We examined the storage dynamics and isotopic composition of soil water over 12 months in three hydropedological units in order to understand runoff generation in a montane catchment. The units form classic catena sequences from freely draining podzols on steep upper hillslopes through peaty gleys in shallower lower slopes to deeper peats in the riparian zone. The peaty gleys and peats remained saturated throughout the year, while the podzols showed distinct wetting and drying cycles. In this region, most precipitation events are <10 mm in magnitude, and storm runoff is mainly generated from the peats and peaty gleys, with runoff coefficients (RCs) typically <10%. In larger events the podzolic soils become strongly connected to the saturated areas, and RCs can exceed 40%. Isotopic variations in precipitation are significantly damped in the organic-rich soil surface horizons due to mixing with larger volumes of stored water. This damping is accentuated in the deeper soil profile and groundwater. Consequently, the isotopic composition of stream water is also damped, but the dynamics strongly reflect those of the near-surface waters in the riparian peats. "pre-event" water typically accounts for >80% of flow, even in large events, reflecting the displacement of water from the riparian soils that has been stored in the catchment for >2 years. These riparian areas are the key zone where different source waters mix. Our study is novel in showing that they act as "isostats," not only regulating the isotopic composition of stream water, but also integrating the transit time distribution for the catchment. KEY POINTS: Hillslope connectivity is controlled by small storage changes in soil unitsDifferent catchment source waters mix in large riparian wetland storageIsotopes show riparian wetlands set the catchment transit time distribution.

Land use and hydroclimatic influences on Faecal Indicator Organisms in two large Scottish catchments: towards land use-based models as screening tools.

Faecal Coliform (FC) bacteria were used as Faecal Indicator Organisms (FIOs) for assessment of microbiological pollution risk in two large, mixed land use catchments in Scotland. FC counts varied spatially in relation to land use and human population and resulting trophic status. These were highest in catchments with a high cover of improved pasture (which was assumed to be a proxy for cattle and sheep grazing densities) and significant human populations. FC counts were lowest in oligotrophic upland areas, where domesticated animal populations were low. In both lowland and upland catchments, peak FC counts occurred under periods of elevated flows during summer. However, in lowland agricultural catchments of higher trophic status, contamination appears to be chronic and occurs all year round. In contrast, upland headwater catchments exhibit more episodic peaks in relation to high flow events. Larger scale catchments integrate the inputs from contrasting head water streams. Spatial variations in stream FC concentrations can be predicted to a first approximation using multiple regression based on catchment characteristics. Land cover was the most important factor, with percentage improved pasture being the primary control and human population being of secondary importance. These two factors could explain 78% of the variation in mean annual FC concentrations and 65% of the 95th percentile. This simple linear model provides a screening tool for rapid assessment of pollution risk in unmonitored catchments. However, improved prediction of short-term dynamics and peak values requires higher resolution sampling and process-based models of FC production, survival and transport. A particularly important need is an improved characterisation of the hydrological connectivity which controls the flux from pollutant reservoirs on the landscape into river channel networks.