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This paper presents an assessment of the impacts of future climate changes on the hydrological characteristics of Harvey River catchment in Western Australia. A conceptual lumped-parameter rainfall-runoff model (HBV model) is used to simulate the catchment hydrological behaviour. Daily observations of rainfall, temperature and discharge and monthly mean potential evapotranspiration from the hydro-meteorological stations within the catchment were used to calibrate and validate the HBV model. The calibrated model was then forced by the downscaled future rainfall and temperature to simulate the daily discharge at the catchment outlet for the mid (2046–2065) and late (2080–2099) of the 21st century. Future climate signals were extracted from a multi-model ensemble of eight Global Climate Models (GCMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) under three Representative Concentration Pathways (RCPs) (RCP2.6, RCP4.5 and RCP8.5). A control run, with the baseline climatic period (1971–2010), was used to represent the current climate status. Results show a noticeable reduction in the mean annual streamflow during the mid-century particularly for the RCP4.5 relative to the current streamflow. By the end of the century, all scenarios revealed a relatively high decline in the mean annual streamflow especially the RCP4.5. The decline in future streamflow ranged between 17–27% during the mid-century and 23–52% by the end of the century.

Prediction of future climate forms one of the tenets of assessing impacts of climate change in various aspects of livelihoods. The ability to validate climate variables generated by relatively coarse global models, at the desired scales, not only adds value to the usefulness of such models but also engenders research on impacts of climate change in various domains. In this study, one of the protocols for downscaling climate variables from coarse Global Circulation Models (GCM), the Long Ashton Research Station Weather Generator (LARS-WG) was applied in the Ngerengere catchment in Tanzania. LARS-WG is a stochastic weather generator which can be used for generation of weather data at single site under both current and future climate condition. The LARS-WG model was calibrated and validated using the observed daily rainfall data for the period 1971–2000 (30 years) in Ngerengere catchment. LARS-WG calibration results indicate a good fit between observed and generated average daily rainfall and temperature indices. The calibrated model was then used to downscale climate attributes from GCMs with appreciable results where it was observed that LARS-WG performed well in generating future rainfall and temperature data series. The results indicated an increase in minimum and maximum temperature between 0.2 and 2.6 °C in the 2050s and between 2.7 and 4.4 °C in the 2080s. The lowest increase in future temperature was noted to occur in October and November and the highest increase to occur in May, June and July. Future rainfall was predicted to decrease by 12–37% in April, May, June and July, while rainfall in the remaining months, was predicted to increase by 3–58%.

Topography plays a major role in the morphology, geochemistry , and mineral inclusion profiles of placer gold from the East Fork of the San Gabriel River. These trends are consistent with a significant change in topographic gradient over a short distance, and coincident with the break in slope along the range-front of the San Gabriel Mountains. Placer gold from above this topographic transition is more rounded and 3-dimensional, with elevated silver in the alloy of the native gold, little evidence of gold enrichment rims, and abundant inclusions of brittle and reactive minerals. Below the topographic transition, placer gold assumes a distinctly flattened form, with lower silver alloy content, thin gold enrichment rims, and rare inclusions of relatively inert minerals. This relationship is observed for placer gold shed from two inferred lode sources within the river catchment, with placer gold from each of these sources being traceable as a unique population over at least 8 km of the river. Significantly, these placer gold properties are distinctive enough to fingerprint gold from specific portions of the placer deposit . These identifying characteristics, with virtually identical morphology and chemical trends, are observed in the large nuggets of the Mel Fisher collection of purported San Gabriel gold. These similarities appear to confirm the provenance of the collection, including identification of the specific locations where each nugget originated.

In this study, we propose to assess climate impact on forest cover (represented by EVI) at multiple scales in areas undergoing substantial land cover change, using Landsat imagery with human-induced land cover change effect excluded. Taking the Qingliu River catchment located in a subtropical humid monsoon area in China as a case study, the results indicate that EVI increases significantly (p 0.01) during 1989-2014 with a magnitude of 0.026/decade. Spatial distribution of EVI is distinct in summer and growing season. Temperature and precipitation show high partial correlations with EVI, with better partial correlation found between EVI and temperature. Their partial correlations with EVI on monthly scale are higher than those on annual scale. Besides, precipitation and pan evaporation show accumulative lag effects (4 months) on forest EVI, while temperature has no lag effect. Finally, an empirical formula is established to quantify the relationship among EVI and its main driving factors (temperature and precipitation) by considering the precipitation threshold (200 mm). The findings should provide scientific supports for local forest management and ecosystem services, and should also support the hydrological effect assessment of vegetation cover change under climate change for the study area.

An accurate assessment of Flash-Flood Potential for certain areas is mandatory for the improvement of flash-flood forecast and warnings. The main aim of the present study is represented by the calculation of Flash-Flood Potential Index within the upper and the middle sector of Prahova river catchment (Romania) by using 4 hybrid models: Logistic Regression-Frequency Ratio (LR-FR) model, Logistic Regression-Weights of Evidence (LR-WoE) model, Support Vector Machine-Frequency Ratio (SVM-FR) model and Support Vector Machine-Weights of Evidence (SVM-WoE). The identification of areas affected by torrential phenomena represents the first step performed in the present research. These areas with a total surface of 260 km2 were divided into training areas (70%) and validating areas (30%). By the mean of Linear Support Vector Machine (LSVM) model, 10 flash-flood conditioning factors were selected and further used for the Flash-Flood Potential assessment. Based on the spatial relationship between areas affected by torrential phenomena and flash-floods conditioning factors characteristics, the FR and WoE coefficients were calculated. In order to be integrated into Logistic Regression and Support Vector Machine (RBF) analysis, these values were standardized. According to the results of the 4 hybrid models used for FFPI calculation, the high and very high Flash-Flood Potential are spread over 33% of the study area. The model performance assessment and results validation were carried out by the mean of the three different methods: i) relative frequency distribution of torrential phenomena pixels within FFPI classes; ii) ROC Curve (Success Rate and Prediction Rate) and AUC value; iii) statistical measures represented by Sensitivity, Specificity and Accuracy.

Investigating the suspended sediment dynamic is useful for gaining a more comprehensive understanding of runoff and sediment yield process. The study analyzes the sediment flow behavior in relation to the flood patterns in the Xichuan River catchment on the Loess Plateau. Based on 23-year hydrological data collected from Zaoyuan hydrological station and K-medoids clustering method, one hundred and twelve flood events data were classified into four flood patterns. The hydrologic features of different flood patterns exhibit significant differences. The values of the mean runoff depth, the mean flood duration, and the mean flood peak discharge decreased as the following order: Pattern A > Pattern C > Pattern D > Pattern B. Each flood pattern results in differing levels of the event sediment yield (SY), the SY of Pattern A (10,275.33 t·km−2) and Pattern C (1196.39 t·km−2) were larger than those from Pattern B (218.84 t·km−2) and Pattern D (693.84 t·km−2). These results indicated that greater attention should be paid to Pattern A and Pattern C because of the largest sediment delivery effect. Multiple stepwise regressions analysis suggested that the contribution of main runoff-related factors to event sediment yield varied with different flood patterns. In addition, hysteretic analysis between suspended sediment concentration and runoff suggested that counter-clockwise and figure-eight loops were the dominant loops. The results provided a useful information to flood pattern classifications and suspended sediment dynamics research, and enriched the sediment control theory at the watershed scale.

The occurrence, distribution and ecological risk assessment of twelve (12) organophosphorus flame retardants (OPFRs) were investigated in sediments from the Vaal River, South Africa. Six halogenated OPFRs [tris-(2-chloroethyl) phosphate (TCEP), three isomers of tris-(chloropropyl) phosphate (TCiPPs), tris-(1, 3-dichloro-2-propyl) phosphate (TDCiPP) and tris-(2, 3 dibromopropyl) phosphate (TDBPP)] and six non-halogenated OPFRs [tris-(n-butyl) phosphate (TBP), tris-(phenyl) phosphate (TPhP), tris-(butyl ethoxy) phosphate (TBOEP), tris-(2-ethylhexyl) phosphate (TEHP), diphenyl- 2-ethylhexyl phosphate (DPEHP) and tris-(m-cresyl) phosphate (m-TCP)] were detected in this study. The concentrations of twelve OPFRs in total (Σ12OPFRs) ranged from 68 to 278 ng g−1 dry weight (dw) with the mean and median of 138 and 120 ng g−1; respectively. The non-halogenated OPFRs showed more abundances than the halogenated OPFRs with TDBPP, TBP, and TBOEP the most abundant compounds. Generally, concentrations of OPFRs in more urbanized region were higher than those in less urbanized regions. When the concentrations of OPFRs and total organic carbon (TOC) were correlated, a moderate and significant correlation (p 1) while TBOEP, TPhP, and TBP posed medium risk (0.1

Study region: Hadejia River Basin (HRB) in North Eastern Nigeria. Study focus: The hydrological trends and variations of surface runoff in Hadejia river catchment were assessed using data spanning 36 years (1980–2015) for proper planning and management of water resources in the basin. New hydrological insight for the region: The temporal and spatial irregularities in the runoff of Hadeia river catchment has been detected. A significant decrease of river discharge from two out of the three downstream stations had been observed. However, there is an increasing trend of the river discharge from all the three upstream stations, though statistically insignificant. The ANOVA [F (5,210) = 106.226, P

The study aims to evaluate the performance of nine empirical rainfall erosivity (R) factor formulas at the Venetikos River catchment, Northwestern Greece. The goal is to select the most appropriate one, for the accurate estimation of soil erosion. Since high temporal resolution precipitation data (required for the analytical calculation of the R-factor, based on the EI30 index) are only available at the Spilaio station, and for a shorter time period (1973–82) than the one the study focuses on (1965–82), a direct validation of R-factor (thus of the empirical equation used for its estimation) can't be applied. Consequently, an indirect validation is attempted considering the catchment's sediment yield, given the convergence between the respective observed and modelled time series. The former was based on field measurements provided by the Greek PPC (Public Power Corporation), while the latter on the (annual; multi-annual) implementation of RUSLE, once for every different R-factor approximation. Provided that all other factors (K, LS, C, P) remain unchanged, the model's relative results (of each application against all others) are only depended on the alternative R-factor values. Regarding the latter, the approximation (thus R-factor equation) that performed best was the one using the Renard and Freimund (1994) [F-based] formula, by displaying the smallest deviations (%) against the observed measurements. All approaches allowed identification of the most susceptible to erosion areas.

Recurring droughts associated with global warming have raised major concern for the agricultural sector, particularly vulnerable small-scale farmers who rely on rain-fed farming such as in the Luvuvhu River catchment. The Standardized Precipitation Evapotranspiration Index (SPEI) and Water Requirement Satisfaction Index (WRSI) were calculated to assess drought on a 120-day maturing maize crop based on outputs of the CSIRO-Mk3.6.0 under RCP 4.5 emission scenario, for the period 1980/81–2089/90. Results by SPEI show that 40–54% of the agricultural seasons during the base period experienced mild drought conditions (SPEI 0 to −0.99), equivalent to a recurrence of once in two seasons. However, WRSI results clearly indicated that stations in the drier regions (annual rainfall

Estimation of 3H discharge from river catchments is important to evaluate the effect of Fukushima Dai-ichi discharge and future planned 3H release to the ocean on the coastal environment. Using a previously developed model based on the tank model and observed 3H concentration in river water, the 3H discharge from the Abukuma River and 13 other rivers in the Fukushima coastal region were estimated from June 2013 to March 2020. The 3H discharge from catchments of the Abukuma River and 13 other rivers in the Fukushima coastal region during 2014–2019 were estimated to be 1.2–4.0 TBq/y. These values were approximately 2–22 times larger than the annual 3H discharge from the Fukushima Dai-ichi after 2016, indicating the significance of 3H discharge from the catchments through the rivers. This estimation is expected to be useful to evaluate and predict 3H concentrations and inventories in the Fukushima coastal region for consideration of planned 3H release to the ocean.

The majority of the carbon worldwide is in soil. In a river catchment, the tight relationship between soil, water and climate makes carbon likely to be eroded and transported from the soil to the rivers. There are multiple variables which can trigger and accelerate the process. In order to assess the importance of the factors involved, and their interactions resulting in the changes in the carbon cycle within catchments, we have studied the catchments of 26 Finnish rivers from 2000 to 2019. These catchments are distributed all over Finland, but we have grouped them into three categories: southern, peatland and northern. We have run a boosted regression tree (BRT) analysis on chemical, physical, climatic and anthropogenic factors to determine their influence on the variations of total organic carbon (TOC) concentration. TOC concentration has decreased in Finland between 2000 and 2019 by 0.91 mg/l, driven principally by forest ditching and % old forest in the catchment. Old forest is especially dominant in the northern catchments with an influence on TOC of 40.5%. In southern and peatland catchments, average precipitation is an important factor to explain the changes in TOC whilst in northern catchments, organic fields have more influence.

Riparian zone vegetation plays an integral role in freshwater ecology, notably by buffering water temperatures, and in providing habitat for the adult stages of many aquatic species. We measured the contribution that riparian vegetation makes to temperature buffering, and how this affects the freshwater fauna, specifically using changes in abundances of baetid may flies for the Luvuvhu River catchment in South Africa. Water temperatures were compared for shaded versus un-shaded sites, and thermal stress between seasons was estimated using a cumulative probability model for the most widespread mayfly species, Dabulamanzia media. It is concluded that thermal stress due to losses in riparian shading could be detected using mayfly abundances in a regular monitoring programme.

Surface water connectivity between rivers and floodplain lakes is essential to maintain biodiversity and ecological functioning in floodplain wetlands. This study proposes a method to analyze the spatial and temporal connectivity using hydraulic modeling and freely available remote sensing data. A novel dynamic connectivity metric introduced here accounts for the entire flow path, which can be a substitute for flow connectivity indicators and statistical connectivity indicators. The metric allows comparing the hydrological connectivity between different phases of a flood event, between different flood events, and potentially between different catchments. The method was applied to the Northern Lakes of the Narran River catchment in New South Wales, Australia. The results indicate that there is no clear transition in the connectivity between different stages of a flood event in the flat Narran River wetland compared with other wetlands connecting to deeper river channels. Thus, the proposed metric brings a more comprehensive observation on hydrological connectivity in floodplain wetlands than previously developed metrics, which is expected to further support ecological and water management studies in river catchments.

Brominated flame retardants (BFRs) compounds have been widely added in a number of products to reduce their flammability. In the present study, the concentrations and distribution of tetrabromobisphenol A (TBBPA) and its derivatives, i.e. tribromophenol dibromopropyl ether (TBPDBPE), tetrabromobisphenol A bis-dibromopropyl ether (TBBPA BDBPE), tetrabromobisphenol A bis-allyl ether (TBBPA BAE) were investigated in sediment samples collected from the Vaal River catchment, South Africa. The results showed that all these pollutants were detected in sediments with TBBPA BAE being the most abundant contaminant. The TBBPA BAE concentrations ranged from 3.5 to 44.4 ng/g (mean 16 ng/g) while the concentration ranged from not detected (nd) to 2.4 ng/g (mean 0.6 ng/g), nd - 21.0 ng/g (mean 6 ng/g) and nd - 2.0 ng/g (mean 0.2 ng/g) for TBPDBPE, TBBPA and TBBPA BDBPE; respectively. Higher concentrations of these pollutants were found in sampling sites receiving effluents of wastewater treatment works (WWTWs) treating some industrial wastewater suggesting effluents might play an important role in the contamination of BFRs in the environment. Negative correlation between TBBPA and TBBPA BAE was observed implying different sources or environmental fates between these pollutants. Overall, the results showed a need for further studies to be undertaken in investigating the presence, fate and sources of alternative halogenated flame retardants in the environment.

Due to the degeneration of water quality globally, water quality models could increasingly be utilised within water resource management. However, a lack of observed data as well as financial resources often constrain the number of potential water quality models that could practically be utilised. This study presents the Water Quality Systems Assessment Model (WQSAM). WQSAM directly utilises flow data generated by systems models to drive water quality simulations. The model subscribes to requisite simplicity by constraining the number of variables simulated as well as the processes represented to only those most important to water quality management, in this case, nutrients and salinity. The model application to the upper Olifants River catchment in South Africa is described. WQSAM was able to use the limited observed data to simulate representative frequency distributions of water quality, and the approach used within WQSAM was shown to be suitable for application to data scarce catchments.

Submarine channels are not stand-alone systems. They are long-lived systems modified by imperceptibly slow processes and rapid gravity flows, in some part controlled by hinterland dynamics. The submarine Zambezi Channel, within the Mozambique Channel, receives sediment from the Zambezi River catchment which has a dynamic tectonic and morphological history. Using recently collected multibeam bathymetry and PARASOUND data we discuss the geomorphology of the Zambezi Channel. Results show this system to be distinct in geomorphologic character when compared to other low-latitude submarine channels, sharing similarities with high-latitude systems. We propose a new, source-to-sink, hypothesis for the evolution of the Zambezi Channel, taking in to consideration hinterland tectonics, palaeo-lake development, river capture and rapid gravity flows. This hypothesis accounts for the unique present-day anatomy of the Zambezi Channel within the dynamic framework of the systems regional setting.

The release of soil arsenic (As) in an unsaturated zone under oxidative conditions and at two temperatures simulating the seasonal effect (15 °C and 23 °C) was studied in four cultivated soils from the Elbe River catchment (Czech Republic, Central Europe). The soils with a low geogenic As background contained from 10 to 50 µg.g−1 of As, mostly originating from atmospheric deposition in the past. The temperature effect on the stability of As in soils was studied in connection with the stability of hydrated iron (Fe) oxides and dissolved organic carbon (DOC), as essential binding partners of As in soils. The temperature impact on As release was related to the actual As binding in soil determined by the sequential leaching. With predominant As binding to amorphous and poorly crystalline Fe phases the higher temperature (23 °C) increased As release up to twice compare to 15 °C. In the soils with a low total Fe and the preferential As binding to well-crystallised Fe phases the temperature effect on As release was negligible. Unlike Fe, the release of DOC is strongly temperature dependent, therefore As mobilisation was controlled by the DOC concentration. A higher experimental temperature (23 °C) supported the formation of DOC and the consequent release of As and Fe into the soil solution.

A mix of catchment-scale controls operate to determine geomorphic river diversity in a catchment. These are contextualised here as imposed and flux controls. Imposed controls do not adjust over geomorphic timeframes and produce the environmental setting in which a river functions. Flux controls are dynamic interactions between flow and sediment that heavily influence geomorphic river diversity. We measure and statistically analyse the network scale mix of imposed and flux controls occurring along longitudinal profiles of various shape. We use this to explain the diversity, pattern and sequence of river types at different positions in a catchment. Using the Richmond River catchment, New South Wales, Australia, as our case study we analyse the imposed controls of slope and valley bottom width and the flux controls of bed material size and gross stream power for five river types, ranging from confined continuous rivers in headwaters to laterally unconfined discontinuous rivers in lowland plains. We find that slope and gross stream power are strong, positively correlated controls on all river types, but act most strongly on rivers with continuous channels. In contrast, bed material size is a dominant control on rivers with discontinuous channels. Slope and gross stream power are also critical for determining the downstream pattern of river types along longitudinal profiles. However, the relationship between these controls is complex as not all rivers are influenced by these controls in the same way. Understanding the mix and patterns of controls operating along longitudinal profiles can be used to explain the variability and pattern of river types we see in the landscape.

This is the first study of broad range of chemical classes CECs conducted in the upper Wisla river catchment including the biggest WWTPs in this region and surface waters. The list of compounds is extensive and the paper provides, for the first time, better understanding of environmental burden from PCPCs in Poland. Cumulative contribution of hypertension pharmaceuticals, nonsteroidal anti-inflammatory drugs (NSAIDs) and lifestyle chemicals was 89% and 95% in wastewater influent, and 75% in wastewater effluent at both WWTPs. Significant removal efficiencies, exceeding 90%, were found for parabens, UV filters, NSAIDs, steroid estrogens, plasticizers, antibacterials/antibiotics, stimulants and metabolites and lifestyle chemicals. The comparison of the average mass loads of CECs between the influent and effluent, has shown that 27% and 29% of all detected CECs were removed by less than 50%. An increase of concentrations of CECs in the effluent was observed for 18% and 20% of all detected CECs in Kujawy and Plaszow WWTPs, respectively. Negative mass balances of fexofenadine, venlafaxine, o-desmethyltramadol, ketamine and temazepam were noted within WWTPs, which are a result of dissolution of persistent contaminants accumulated in aggregates and/or back-transformation or de-conjugation of metabolites into parent compounds. 44 CECs were detected in surface waters located upstream and downstream of the WWTPs. The concentrations of compounds were largely dependent on the dilution factor of WWTP discharge. The risk quotation (RQ) values for compounds present in surface waters were calculated in relation to their potential for bioaccumulation. Among compounds with high potential for bioaccumulation, with log KOW ≥ 4.5, diclofenac, atorvastatin and triclosan were found to be of high risk. Many CECs with high, moderate or even low environmental impact have shown high potential for bioaccumulation and should be considered as priority at the same risk level. Moreover, possible synergistic action is still of concern.

Study region The Pra river catchment in Ghana, West Africa. Study focus Knowledge of the spatio-temporal distribution of wet and dry spells are crucial for rain-fed agriculture at the Pra River catchment. This study characterised spells and their associated atmospheric dynamics at the Pra river catchment. Specifically, the variability of historical and future wet and dry spells and atmospheric dynamics on the rainfall and spell patterns at the catchment were studied. New hydrological insights Short duration spells have a higher occurrence at the catchment as compared to long duration spells. Seasonally, short duration dry spells are most common in December–February, whereas wet spells are expected in March–May. Future scenarios show an increase in both wet and dry spells. Composites of the atmospheric dynamics for 2–3 day dry spells show moisture convergence over the entire catchment, with lower total column water levels. However, there is a dipole of moisture convergence and divergence for wet spell composites, with higher than normal total column water. An anticyclonic circulation, inducing a ridge at 500 hPa, coupled with low-level southerlies at 850 hPa act to support wet spell occurrences in JJA. The findings contribute to sub-seasonal and seasonal forecasting, and hence will improve agricultural practices in the catchment in support of food security.

Our previous study demonstrated that high levels of antibiotic resistance genes (ARGs) in the Haihe River were directly attributed to the excessive use of antibiotics in animal agriculture. The antibiotic residues of the Xiangjiang River determined in this study were much lower than those of the Haihe River, but the relative abundance of 16 detected ARGs (sul1, sul2 and sul3, qepA, qnrA, qnrB, qnrD and qnrS, tetA, tetB, tetW, tetM, tetQ and tetO, ermB and ermC), were as high as the Haihe River particularly in the downstream of the Xiangjiang River which is close to the extensive metal mining. The ARGs discharged from the pharmaceutical wastewater treatment plant (PWWTP) are a major source of ARGs in the upstream of the Xiangjiang River. In the downstream, selective stress of heavy metals rather than source release had a significant influence on the distinct distribution pattern of ARGs. Some heavy metals showed a positive correlation with certain ARG subtypes. Additionally, there is a positive correlation between individual ARG subtypes and heavy metal resistance genes, suggesting that heavy metals may co select the ARGs on the same plasmid of antibiotic resistant bacteria. The co-selection mechanism between specific metal and antibiotic resistance was further confirmed by these isolations encoding the resistance genotypes to antibiotics and metals. To our knowledge, this is the first study on the fate and distribution of ARGs under the selective pressure exerted by heavy metals in the catchment scale. These results are beneficial to understand the fate, and to discern the contributors of ARGs from either the source release or the selective pressure by sub-lethal levels of environmental stressors during their transport on a river catchment scale.

The study investigated the degradation behaviors of swine farm tetracyclines (TCs) at a catchment scale and explored whether multi-pond systems could be beneficial to the interception of TCs so as to reduce the pollution risk to receiving rivers. The occurrence and migration of 12 kinds of tetracycline antibiotics, including their degradation products, were studied in four swine farms of the Meijiang River basin in China. The migration paths of the TCs were examined through sampling and analyzing the soil and/or sediment at different points along the swine wastewater outlet, which included sewer, sewage pond, mixed-canal (stream and sewage), farmland (paddy and upland soil) and finally the river. TC concentrations of all collected samples were obtained by solid phase extraction followed by measurement with high-performance liquid chromatography tandem mass spectrometry. The results showed that sediment TC concentrations varied greatly in different swine farms, from mg·kg −1 to μg·kg −1 levels. TCs had different decay patterns along different migration paths, such that TCs decayed exponentially in paddy soil, while linearly in sewer and mixed canal. The concentrations of TCs and their degradation products decreased in the order: sewer sediment > sewage pond sediment > mixed-canal sediment > paddy soil > upland soil, indicating that TCs tend to be more easily intercepted and accumulated in water-sediment systems such as ponds. Therefore, the multi-pond system could be an effective way to prevent TCs from migrating into rivers. These results provided essential information for contamination control of antibiotics in aquatic environments.

Spatially explicit analyses of ecosystem services are needed by policy-makers. The lack of spatial water supply data is an obstacle to spatially explicit analyses. In this study, the spatial water quality is obtained by taking water samples at key sites during key periods. The relationships between water quality and ecosystem services were analyzed at a small watershed scale, using areas ranging from 0.03 km2 to 160.19 km2. Our results shows that (1) water quality indexes are negatively correlated with the provision of regulating ecosystem services, except for NPP (net primary product). (2) That NPP is positively correlated with water quality indexes and crop field ratio suggests increasing NPP is correlated with degradation of water quality, because of the fertilization in croplands. (3) The growth of crop is the main contribution to the variation in NPP. Therefore, the relationship between NPP and forest area ratios can’t reflect the real relationship between carbon sequestration and forest. (4) The ecosystem services bundles analysis at small watershed scale would benefit the understanding of local characteristics of interactions among ecosystem services and help making targeted policy meets the needs of local conditions in diverse landscapes.

While sediment tracing has been typically applied to identify sediment sources that are difficult to measure by gauging (monitoring), it can also be useful in estimating relative sediment yields from gauged river catchments. The major and trace element composition of river sediments from eleven locations in the 130000 km2 Burdekin River catchment, northeastern Australia was analysed to examine relative contributions from upstream source areas in the 2011/12water year. Sediment tracing results are compared against estimates derived fromsediment load monitoring at three locations. Comparisons show that there is good agreement between tracing results and monitoring data at one of the tributary confluences. At the second site, notable contrastswere found between the load estimates from the monitoring and tracing data. At this site a large impoundment occurs between the upstream sampling/gauging sites for source sediments and the downstream sampling/gauging sites for target sediments. The contrast is likely caused by temporal variations in particle size distributions of suspended sediment fromeach river and differential trapping efficiencies in the impoundment for sediment derived fromthe different tributaries. In the absence of the detailed particle size data and trapping efficiency estimates, sediment tracing provides the unique opportunity to elucidate source contributions of the finer fractions of suspended sediment. At a third site, where there were recognised measurement gaps in the monitoring data during large discharge events, the relative load estimates fromthe tracing data provided a means of constraining the recognized uncertainty of monitored load estimates.We conclude that sediment tracing can be used as a valuable adjunct to monitoring data particularly in remote, large and data-sparse catchments. Both tracing results and monitoring data showthat the Upper Burdekin River and Bowen-Bogie Riverswere the dominant source of the b10 μm sediments being delivered to the GBR lagoon from the Burdekin River catchment in the 2011/12 water year. More substantial contribution from the Belyando-Suttor Rivers indicated by the tracing results than the monitoring data is attributed to preferential delivery of the 1–10 μm sediments through the impoundment and has uncovered a knowledge gap in sediment budgets in the catchment.

Organochlorine pesticides (OCPs) were investigated in passive air and soil samples from the catchment area of the Indus River, Pakistan. ∑15OCPs ranged between 0.68 and 13.47 ng g(-1) in soil and 375.1-1975 pg m-(3) in air. HCHs and DDTs were more prevalent in soil and air compartments. Composition profile indicated that β-HCH and p,p'-DDE were the dominant of all metabolites among HCHs and DDTs respectively. Moreover, fBC and fTOC were assessed and evaluated their potential role in the distribution status of OCPs. The fTOC and fBC ranged between 0.77 and 2.43 and 0.04-0.30% respectively in soil. Regression analysis showed the strong influence of fBC than fTOC on the distribution of OCPs in the Indus River catchment area soil. Equilibrium status was observed for β-HCH, δ-HCH, p,p'-DDD, o,p'-DDT, TC, HCB and Heptachlor with ff ranged between 0.3 and 0.59 while assessing the soil-air exchange of OCPs.

Study region: Kaleya River Catchment in southern Zambia. Study focus: The ability of a landscape hydrology approach to detect controls on water availability in a fragmented landscape to inform interventions under a changing environment was investigated. Simple and measurable climatic and landscape pattern attributes were analysed using change detection, trend analysis and backward variable elimination with Partial Least Squares Regression (PLSR) to identify controls on seasonal river flows and how landscape components could be enhanced to augment natural river flows. New hydrological insights for the region: Landscape pattern showed increasing fragmentation, expansion of irrigated cropland and reservoirs and loss of forestland. Significant increasing trends (p

Microplastics have pulled the alarm for its far-reaching impacts in the environment and potential risks to human health. Here, we first investigated the microplastic pollution in the Zhangjiang River of southeastern China. Water samples were collected across a river catchment using bulk sampling method. The abundance, distribution, and characteristics of microplastics were analyzed using stereomicroscopy and micro-Raman spectroscopy. The results indicated that microplastic abundance ranged from 50 to 725 items m-3 with an average of 246 items m-3. PP and PE were the major polymers and accounted for ~75%. The dominant shape, color, and size of microplastics are fragment, white, and 0.5-1 mm, respectively. The findings established the baseline information on the microplastic pollution in the Zhangjiang River, which may improve the knowledge of sources of microplastic debris to the local watershed and future evaluation on the role of river catchments in transporting microplastics to the estuary and beyond into the ocean.

Analysis of drought on rain-fed maize production in the Luvuvhu River Catchment was measured using the Water Requirement Satisfaction Index (WRSI). Computation of WRSI was performed using a crop water balance model in Instat+ software for a 120-day maturing maize crop using nine different planting dekads from October to December. This study made use of seven weather stations, which adequately represent climatic and geographical environments of the catchment, containing historical rainfall and temperature data from 1974 to 2015. The non-parametric Spearman’s Rank Correlation test was conducted to determine drought trends. Thereafter, probabilities and extreme widespread dry and wet agricultural seasons were analysed using STATISTICA software. Results revealed that since the 1980s, the catchment had been subjected to frequent drought conditions, with an average frequency of once every two to three seasons. Extreme drought episodes (WRSI

Contemporary river forms and processes can be heavily influenced by the legacies of anthropogenic disturbances to river systems. Knowledge of the historical range of river adjustment can be used to develop an understanding of a river's ‘expected’ character and behaviour. Drawing upon the case study of Richmond River Catchment, New South Wales, Australia, we track the history of geomorphic river adjustment from the time of European colonisation in the mid-late nineteenth century. We use this study to develop an approach, called the ‘Behavioural sensitivity logical tree’ that can be applied to assess and quantify reach scale behavioural sensitivity, defined as the ease with which geomorphic units and associated water, sediment and vegetation interactions adjust within the expected behavioural regime. We use the results to categorise rivers as Fragile, Active sensitive, Passive sensitive, Insensitive and Resistant. Fragile rivers have a behavioural sensitivity >75% and have the propensity to undergo wholesale river change such that a new river type and behavioural regime is created. Active sensitive rivers have a behavioural sensitivity ranging from 50%–75% and have the ability to re-configure within their contemporary behavioural regime. The behavioural sensitivity of Passive sensitive rivers lies between 20%–50%. These rivers have the ability to maintain their behavioural regime and withstand adjustment. Insensitive rivers have a behavioural sensitivity ranging from 5%–20%. They do not readily adjust and may contain significant antecedent elements that limit geomorphic adjustment. Resistant rivers have a behavioural sensitivity

Exploring the impacts of mining-related human activities on catchment streamflow time series can facilitate understanding of streamflow response to external factors, including climatic inputs. This study selects the Goulburn River catchment that is located in southeastern Australia having more than 100 years of streamflow observations and more than 90 years of mining history, and divides the streamflow period from 1913 to 2015 into four sub-periods: 1913–1920 (no mining), 1921–1950 (small-scale underground mining), 1951–1980 (commence of new underground mining) and 1981–2015 (large-scale mining of open cut and underground mining). Process-based hydrological modelling (SIMHYD), simple one-parameter hydrological model (Budyko-based method) and a data-driven approach (the double mass curve, DMC), are used to assess mining-related centennial streamflow changes and to quantify relative contributions of climate variability and mining activities on streamflow. These results show that streamflow increased during periods of underground mining, which is likely due to over-pumping to sustain the underground mining. The difference between the observed streamflow and the SIMHYD simulated was very marginal in the reference period of 1913–1920; while it increased by 3.39 mm yr−1 in 1921–1950 and by 10.51 mm yr−1 in 1951–1980. The DMC slope increased from 0.021 in 1913–1920 to 0.025 in 1921–1950, then 0.033 in 1951–1980. These impacts of underground mining on increased streamflow have been greatly reduced and even become negative when open cut mining was largely expanded. The average difference of streamflow during the period of 1981–2015 was reduced from 10.51 mm yr−1 to 2.84 mm yr−1. The DMC slope decreased from 0.033 in 1951–1980 to 0.027 in 1981–2015. The contributions between climate changes and mining activities to streamflow changes estimated using these methods are consistent in trends in different mining periods, but noticeably different in magnitudes.

The global warming and climate changes determined a considerable increase in the frequency of floods and their related damages. Therefore, the high accuracy prediction of flood susceptible areas plays a key role in flood warnings and risk reduction. The main objective of this study is to propose novel hybridizations of fuzzy Analytical Hierarchy Process (FAHP), Index of Entropy (IoE), and Support Vector Machine (SVM) for predicting the areas susceptible to floods. Buzau river catchment (Romania) was the area on which the present study was focused. In this regard, a database with 205 flooded locations, 205 non-flood locations and 12 flood predictors was established and used to train and validate the flood susceptibility models. The performance of the proposed models was evaluated using the Receiver Operating Characteristic (ROC) Curve and statistical metrics. The results show that all the hybrid models have a high prediction performance and outperform the stand-alone models. Among them, the SVM-IoE model (AUC = 0.979) has the highest performance, followed by the FAHP-IoE (AUC = 0.97), IoE (AUC = 0.969), SVM (AUC = 0.966) and FAHP (AUC = 0.947). These results highlight a very high efficiency of all the applied models. The application of the models mentioned above revealed that a percentage between 12.5% (FPIIoE) and 21.2% (FPIFAHP) of the study area is characterized by high and very high exposure to these hydrological hazards.

In this paper, the HBV-TEC hydrological model is presented. The development of this model version, aims to provide researchers and scholars with a stable and robust implementation of the HBV hydrological model based on the R programming language. To evaluate its performance, the HBV-TEC model was applied to three subcatchments of the Aguacaliente river catchment, an experimental catchment located in the province of Cartago, Costa Rica. Results suggest a satisfactory performance of the model for two subcatchments and an unsatisfactory performance of the remaining subcatchment; most of which could be attributed to unsufficient meteorological data along with a highly heterogeneous spatial rainfall-distribution.

Usually parameters of water reservoirs are determined on the base of water balance equation with discreteness 10 days (decade). The values of such equation are calculated on the data base for the long time series. Last half of century is observed a change of different climatic characteristics, in particularity precipitations, which are an element of water balance and has very significant influence on runoff to water reservoir. Consequently there is need to simulate precipitation according to last time of series which has more short duration but more reality. However we must take to consideration a big amount of different scenarios of precipitation both for annual values and for the internal year intervals. Accordingly main purpose of the scientific work is the checking of the method for simulation artificial rows of precipitation according to climatic changes. The next problems were decided: determination of statistical parameters and trends according to data observation for the precipitation; assessment of stationary of the time series of observations; simulation of artificial rows of precipitation according to climatic changes; check of the method for simulation artificial rows of precipitation. Object of research was chosen a catchment of water reservoir of Moscow region. The method Monte Carlo (variant of fragments) was used for simulation of precipitation on territory of the river catchment. The results have showed that the used method can be applied for simulation of precipitation for the studied object. It is obviously that the method must be verified for each object, and if it is necessary-the method may be changed.

Summary A long time series of damaging flood records in Northern Portugal for 1871–2011, gathered from a large number of documentary sources, is analyzed. The relationships between damaging floods (DFs) and relevant circulation weather types (CWTs) are also assessed. The DFs database has 1861 records and CWTs are identified using the 20th century reanalysis dataset v2. A coefficient of effectiveness (CE) is calculated for each weather type in order to assess DF–CWT relationships. Furthermore, conditions in the 10 days preceding a DF outbreak, type of flood and season were taken into account in CE calculations. The DF occurrences were responsible for 186 killed people, 59 injured, 29 missing, 1873 displaced and 15,924 homeless people. The monthly frequencies each CWT show that anticyclonic (A) and easterly wind (E) types are prevalent in winter, whereas R tends to prevail in the summer half of the year. However, the results show that the cyclonic (C) type has a positive frequency with DF occurrence (i.e. anomalously frequent), both on the DF day and on the nine previous days. The C type is commonly associated with southwesterly flow and unsettled weather conditions over Portugal, which are favorable to rain-generating mechanisms. The results also highlight some seasonal variation: in autumn, winter and spring, the C type is largely related to DFs, while the A and E types acquire higher preponderance in the summer. In effect, the latter two CWTs may trigger thunderstorms and heavy precipitation episodes in the Douro River catchment in summer.

To investigate the source of Pb within Bohai Bay, Pb concentrations and Pb isotopic compositions (Pb-204, (206)pb, Pb-207, and Pb-208) of surface sediments in this area were determined. The Pb concentration in this bay varied widely from 6.9 to 39.2 mu g/g (average: 21.8 +/- 7.8 mu g/g), and the Pb isotopic compositions ranged from 0.8338 to 0.8864 (average: 2.0997 +/- 0.0180) for Pb-208/Pb-208 and from 2.0797 to 2.1531 (average: 0.8477 +/- 0.0135) for Pb-207/Pb-206, presenting in three distinct clusters. The Pb isotopic ratios of sediments from the northeastern (NE zone) and northwestern (NW zone) coastal areas were significantly influenced by anthropogenic sources such as coal combustion and automobile emission. In sediments from the central and southern Bohai Bay (C-S zone); however, Pb mainly originated from the Yellow River catchment, as a result of lithogenic sediment (from rock weathering) accumulation. The Pb isotopic ratios further indicate that, apart from riverine inputs, the neighboring large-scale ports and aerosols significantly contributed to the anthropogenic Pb contained in these sediments. Pb contamination in the Haihe and Luanhe river mouths as well as in the regions near ports is also suggested from anthropogenic enrichment factors. As cities and ports continue to develop around Bohai Bay, a long-term extensive sewage monitoring program is highly recommended. (C) 2015 Published by Elsevier Ltd.

Hydrologic modelers are confronted with the challenge of producing estimates of the uncertainty associated with model predictions across an array of catchments and hydrologic flow regimes. Formal Bayesian approaches are commonly employed for parameter calibration and uncertainty analysis, but are often criticized for making strong assumptions about the nature of model residuals via the likelihood function that may not be well satisfied (or even checked). This technical note outlines a residual error model (likelihood function) specification framework that aims to provide guidance for the application of more appropriate residual error models through a nested approach that is both flexible and extendible. The framework synthesizes many previously employed residual error models and has been applied to four synthetic datasets (of differing error structure) and a real dataset from the Black River catchment in Queensland, Australia. Each residual error model was investigated and assessed under a top-down approach focused on its ability to properly characterize the errors. The results of these test applications indicate that a multifaceted assessment strategy is necessary to determine the adequacy of an individual likelihood function.

Malaba River in Uganda a focal area to the Lake Kyoga basin is prone to climate change because of its heavy reliance on rainfall as its major flow contributor. The impacts of climate change on streamflow in Malaba River were assessed using LARS-WG downscaling model and Soil and Water Assessment Tool (SWAT) model. This was achieved by downscaling the future (2020-2050) precipitation and temperature variables for A1B and A2 scenarios and simulating the projected climate with calibrated LARS-WG and SWAT models for the two scenarios. The SWAT calibration (1992 - 1999) and validation (2000 - 2004) NSE results were respectively 0.55 and 0.35. Results indicated that the projected areal rainfall will increase by 0.34 mm per year for A1B which is averagely 1% less than the baseline period. Areal rainfall for A2 scenario will increase by 0.41 mm per year which is averagely 9% more than the baseline period. The Flow Duration Curve analyses indicated that the A2 scenario displayed higher flows for all the percentiles as compared to the baseline flows while A1B scenario has lower flows for percentiles less than 50, and equal or slightly higher flows for percentiles greater than 50 as compared to the baseline flows.

A series of investigations of water and sediment discharge from the glacierized Ebba River catchment (53 km2, located in the Billefjorden area in the central part of Spitsbergen) was carried out during the ablation seasons of 2008–2010. The study included hydrometric measurements at the catchment closing profile, identification of meteorological factors, and specification of the suspended and dissolved sediment load and of the water's chemical composition. The study evidenced a typical water regime for proglacial rivers, as well as its diversification in subsequent ablation seasons being determined mainly by thermal conditions. Moreover, during the study, the chemical (1 t km −2 d −1) and mechanical denudation (2.7 t km −2 d −1) indices were calculated. These rates documented the independent nature of the water supply system and the water and matter dynamics of the glacierized catchment.

Understanding the impact of climate change on water resources is essential to sustainable development. Urumqi River, a medium-size headwater catchment in the Tianshan mountains, was chosen to evaluate the impact of climate change on its discharges, where impacts of human activities on water are negligible and the influence of glacier melt is minor as far as the mountainous outlet is concerned. Analysis of the time series of temperature, precipitation and river discharge of the hydrological station at the mountainous outlet from 1959 to 2006 was carried out using different statistical methods, including linear regression, Mann–Kendall test and wavelet analysis. Although both temperature and precipitation show a significant upward trend with a gradient of 0.02 °C/y and 2.08 mm/y, respectively, there is no significant rising trend in the stream discharge. The reasons are attributed to the hysteresis and buffering effects of groundwater in conveying the change from precipitation to stream discharge. Common short periods of less than 8 years exist in the three time series, which is a common trend in NW China. Precipitation has stronger influence on stream discharge than air temperature throughout the 48 years of instrumental records in the Urumqi River catchment.

The study on bedload transport was conducted on the gravel-bed Scott River catchment with a glacial alimentation regime, located in the NW part of the Wedel Jarlsberg Land (Spitsbergen) with subpolar climatic conditions. In the melt season of 2010, bedload transport rate was continuously monitored at 24-hour intervals by means of four River Bedload Trap devices aligned across the width of the channel. The maximum bedload transport rate varied strongly at portions of the cross section from 16 to 152 kg m− 1 d− 1 in cross-profile I (c-p I) and 4 to 125 kg m− 1 d− 1 in cross-profile II (c-p II). The maximum channel-mean bedload transport rate (qa) amounted to 54 kg m− 1 d− 1 (c-p I) and 35 kg m− 1 d− 1 (c-p II). Mean daily bedload discharge (Qb) was estimated at a level of 97 kg day− 1 (c-p I) and 35 kg m− 1 d− 1 (c-p II), and the total bedload yield was determined at approx. 4345 kg in the measurement period (2086 kg — c-p I; 2203 kg — c-p II from 13.07 to 10.08). The analysis of the relationship between channel-mean bedload transport rate and water velocity or shear stress revealed a significant value of the correlation coefficient (R2 = 0.6). Discharge and rate of bedload transport were dependent on the weather and number of days with flood discharge. Approx. 58% of the entire discharged bedload was transported during 3 violent ablation–precipitation floods. Bedload grain size distribution was right-skewed and showed moderate sorting.

Most spatiotemporal studies treat spatial and temporal analysis separately. However, spatial and temporal changes occur simultaneously and are correlated. In this study, we propose a generic framework to simultaneously analyse the spatial and temporal variations of water quality on a catchment scale. Specifically, we analyse the heterogeneity of temporal evolution of water quality data among different sampling sites, and the heterogeneity of spatial distribution of water quality data over different sampling times, respectively, by integrating the techniques of normalized mutual information, dynamic time wrapping and cluster analysis. To bring deep insight into the spatiotemporal variations, inter-change and intra-change are further defined and distinguished, respectively. Taking the Fuxi River catchment as a case study, results indicate that the proposed framework is intuitive and efficient. Beyond this, the generic framework can be expanded for other catchments and various environmental data.

Study region: This study was conducted in Soutloop River Catchment, Northern Cape, South Africa. Study focus: Although hydrologic models play a critical role in the management of natural resources in arid areas, their application is challenged by the scarcity of data for calibration and validation. Therefore, this study aimed at to configure, calibrate and validate SWAT model in a data-scarce catchment by using the regionalization with physical similarity approach. This approach uses dual calibration and validation procedure, i.e., one in the donor catchment (by using SWAT-CUP (SWAT Calibration and Uncertainty Programs) and the other on the study catchment (by manual calibration and verification). New hydrological insights for the region: Based on the sensitivity analysis, sixteen parameters were calibrated by SWAT-CUP. The result from the uncertainty analysis indicated acceptable values of both the R-factor (0.8**** Values are the averages of the calibration and validation procedures.) and P-factor (0.7**). The model performance evaluation also showed acceptable ranges of values (e.g., NS was 0.76** and R2 was 0.78**). However, the main calibration and validation process was conducted outside the target catchment, though it was assumed that the donor and target catchments have similar hydrological responses. Therefore, the study suggested further inspection methods to minimize the model uncertainty in the study catchment. This study enables researchers to exploit the river eco-regional classifications of South Africa to apply hydrologic models to estimate the components of water balance in arid/semi-arid catchments. Keywords: Arid catchments, Calibration, Hydrologic models, Regionalization, SWAT model, South Africa

Study region: Guadiana international catchment, located in the Iberian Peninsula. Study focus: The Guadiana River catchment has registered an intense and speed up modification of its natural regime over the last few decades to cope with water scarcity. Such modifications pose a serious challenge to the development of improved management tools as information on available water resources is often not detailed enough. This study aimed to simulate the flow regime of the Guadiana River using the MOHID-Land model during a 30 years period. Two scenarios were defined by considering (or not) inputs from reservoirs. Model performance was assessed by comparing simulated and measured monthly streamflow at 24 hydrometric stations influenced (9 stations) or not (15 stations) by reservoir management. New hydrological insights for the region: Streamflow simulations produced quite acceptable estimates for most of the hydrometric stations not influenced by reservoirs. However, results also showed the importance of non-simulated processes (e.g., groundwater abstractions) to the accurate prediction of the Guadiana flow regime. For the stations influenced by reservoir management, model simulations generally overestimated streamflow measurements. Information related to reservoir management needs thus to be made clearer for achieving better results, which can only be accomplished when national water agencies improve their cooperation protocols. Further model limitations were also addressed as well as the necessary developments for improving streamflow estimates in future modeling applications. Keywords: Distributed model, Iberian Peninsula, MOHID-land, Streamflow, Water scarcity

Concentrations of widely used antibiotics were predicted to be the highest in the Haihe River Catchment across China previously, potentially resulting in high ecotoxicological risks in this region. As a result of growing usage and regulation of antibiotic use in animals, the pattern of use may have altered temporally for different antibiotics. It is important to monitor the occurrence of antibiotics within different categories for understanding their mass loading to the catchment and the potential ecotoxicological risks involved. This study investigated the seasonal occurrence and spatial variation of 15 antibiotics in the Haihe River Catchment during 2016–2017. The investigated compounds included veterinary antibiotics, human-use antibiotics, and those intended for both human and animal use. Measurements reported from previous studies were compared with the results of this study and indicated that the use of veterinary antibiotics is probably increasing around the catchment. The ∑antibiotics concentration (i.e. the summed concentration of the 15 target antibiotics) ranged from 414 to 1951 ng/L, with an average of 821 ng/L. Discharges from wastewater treatment plants were the main sources of these compounds. The mass loading of antibiotics to the river waters was higher during wet seasons than during dry seasons. The mass fluxes of the antibiotics continuously increased towards the lower reaches of the rivers. The total annual input of the antibiotics from the Haihe River and Yongdingxin River into the Bohai Bay was 5008 kg/yr. Ofloxacin, trimethoprim, leucomycin, anhydro erythromycin and florfenicol were the predominant antibiotics, whilst amoxicillin, anhydro erythromycin, ofloxacin, norfloxacin and enrofloxacin may pose high ecotoxicological risks to the investigated aquatic ecosystem. Several antibiotics selected in this study were reported for the first time in this catchment. This study provides important information for chemical management and indicates that further monitoring is needed on the more harmful and veterinary antibiotics in the catchment. Keywords: Haihe River Catchment, Antibiotics, Mass flux, Diffuse pollution, Ecotoxicological risk

Different methods are used to calculate the amount of erosion. Assessment of erosion factors through the use of spatial data integration is the most common method. Generally, RUSLE (3D) erosion model is preferred in the implementation of this method. Current study identified the erosion risk levels and distribution along with annual soil loss according to RUSLE (3D) erosion model in Lower Asi River Basin sample. Geographical Information Systems (GIS) and Remote Sensing (RS) methods and techniques were used in implementing the RUSLE model. Results of analysis show that the basin area experiences low ( -1 y -1 ) levels of erosion the most (1787.40 km 2 - 41.40%) and very severe (150 - > t ha -1 y -1 ) levels of erosion the least (154.75 km 2 - 3.58%). Areas with high levels of erosion are the slope areas with high declivity. Total annual soil loss in the basin area was calculated to be 50.66 t ha -1 y -1 and average annual soil loss in the basin area was calculated to be 10.74 t ha -1 y -1 . These values are lower than those of neighboring (Seyhan River) basin.

A GIS based pesticide risk indicator that integrates exposure variables (i.e. pesticide application, geographic, physicochemical and crop data) and toxicity endpoints (using species sensitivity distributions) was developed to estimate the Predicted Relative Exposure (PREX) and Predicted Relative Risk (PRRI) of applied pesticides to aquatic ecosystem health in the Lourens River catchment, Western Cape, South Africa. Samples were collected weekly at five sites from the beginning of the spraying season (October) till the beginning of the rainy season (April) and were semi quantitatively analysed for relevant pesticides applied according to the local farmers spraying programme. Monitoring data indicate that physicochemical data obtained from international databases are reliable indicators of pesticide behaviour in the Western Cape of South Africa. Sensitivity analysis identified KOC as the most important parameter influencing predictions of pesticide loading derived from runoff. A comparison to monitoring data showed that the PREX successfully identified hotspot sites, gave a reasonable estimation of the relative contamination potential of different pesticides at a site and identified important routes of exposure (i.e. runoff or spray drift) of different pesticides at different sites. All pesticides detected during a monitored runoff event, were indicated as being more associated with runoff than spray drift by the PREX. The PRRI identified azinphos-methyl and chlorpyrifos as high risk pesticides towards the aquatic ecosystem. These results contribute to providing increased confidence in the use of risk indicator applications and, in particular, could lead to improved utilisation of limited resources for monitoring and management in resource constrained countries.

In Finland, acid sulfate (AS) soils constitute a major environmental issue. These soils leach considerable amounts of metals into watercourses, causing severe ecological damage. As small hot spot areas affect large coastal waters, mapping constitutes an essential step in the management of AS soil environmental risks (i.e. to target strategic places where to put mitigation). The primordial aim of this study was to evaluate the predictive classification abilities of an Artificial Neural Network (ANN) for AS soil mapping. The Sirppujoki River catchment (460 km2) located in south-western Finland was selected as study area. An ANN called Radial Basis Functional Link Nets (RBFLN) was applied in order to create probability maps for AS soil occurrences in the study area. This method required the use of aerogeophysical, quaternary geology and elevation data, as well as known AS soil and non-AS soil sites. Applying the RBFLN method, we generated different probability maps. For the most accurate probability map, the combined very high and high probability areas covered 23% of the study area and contained 94% of the validation points corresponding to AS soil occurrences. The combined low and very low probability areas occupied the remaining 77% of the study area and contained all the validation points corresponding to non-AS soil sites. These results being consistent with previous studies and verified by expert assessment, the RBFLN method demonstrated reliable and robust predictive classification abilities for AS soil mapping in the study area. This spatial modelling technique allows the creation of valid and comparable maps, and represents a powerful development within the AS soil mapping process, making it faster and more efficient. Consequently, we recommend the RBFLN modelling, finalized by an expert assessment, for AS soil mapping.

The aim of this work was to study the influence of watershed heterogeneity on the radionuclide contents of suspended particulate matter (SPM) in a large Mediterranean river. As the Rhone River catchment is characterized by a high climatic and geological heterogeneity, floods can be distinguished according to their geographic origins. Long-term time series of particles associated with radionuclides acquired in the framework of radiological surveillance provide a relevant dataset to investigate the variability of radionuclide contents. The SPM exported during Mediterranean floods differ from other floods as they display higher 238U and 232Th contents and the lowest activity ratio 137 Cs/ (239+240) Pu; these properties could be related to bedrock type and erosion process characteristics and/or to source term differentiation.

Stewardship programs providing financial incentives for conservation on private lands are increasingly common. We estimate the potential costs of a stewardship program in the Daly River catchment, Northern Territory, which would underwrite the cost difference between routine land management and the additional requirements of conservation management on grazing properties. Based on survey responses from landholders, we first assess the current costs of land management in the catchment and use regression to identify key drivers of spatial variation in both routine land management costs and conservation-oriented management costs. We define conservation-oriented management costs as the costs required to meet objectives for both routine property management and conservation. We then estimate the additional costs of conservation management over and above routine land management at an average of $1.99 per ha. We conclude that, if the most cost-effective properties are targeted, an annual budget of $1 million would support stewardship agreements covering 90% of the catchment's area. Much of the cost-effectiveness of stewardship payments would come from the significant economies of scale in managing large pastoral properties and leveraging the costs of routine land management already met by landholders.