Perennial rivers and streams make a disproportionate contribution to global carbon (C) cycling. However, the contribution of intermittent rivers and ephemeral streams (IRES), which sometimes cease to flow and can dry completely, is largely ignored although they represent over half the global river network. Substantial amounts of terrestrial plant litter (TPL) accumulate in dry riverbeds and, upon rewetting, this material can undergo rapid microbial processing. We present the results of a global research collaboration that collected and analysed TPL from 212 dry riverbeds across major environmental gradients and climate zones. We assessed litter decomposability by quantifying the litter carbon-to-nitrogen ratio and oxygen (O2) consumption in standardized assays and estimated the potential short-term CO2 emissions during rewetting events. Aridity, cover of riparian vegetation, channel width and dry-phase duration explained most variability in the quantity and decomposability of plant litter in IRES. Our estimates indicate that a single pulse of CO2 emission upon litter rewetting contributes up to 10% of the daily CO2 emission from perennial rivers and stream, particularly in temperate climates. This indicates that the contributions of IRES should be included in global C-cycling assessments.

Temporary streams are those water courses that undergo the recurrent cessation of flow or the complete drying of their channel. The structure and composition of biological communities in temporary stream reaches are strongly dependent on the temporal changes of the aquatic habitats determined by the hydrological conditions. Therefore, the structural and functional characteristics of aquatic fauna to assess the ecological quality of a temporary stream reach cannot be used without taking into account the controls imposed by the hydrological regime. This paper develops methods for analysing temporary streams' aquatic regimes, based on the definition of six aquatic states that summarize the transient sets of mesohabitats occurring on a given reach at a particular moment, depending on the hydrological conditions: Hyperrheic, Eurheic, Oligorheic, Arheic, Hyporheic and Edaphic. When the hydrological conditions lead to a change in the aquatic state, the structure and composition of the aquatic community changes according to the new set of available habitats. We used the water discharge records from gauging stations or simulations with rainfall-runoff models to infer the temporal patterns of occurrence of these states in the Aquatic States Frequency Graph we developed. The visual analysis of this graph is complemented by the development of two metrics which describe the permanence of flow and the seasonal predictability of zero flow periods. Finally, a classification of temporary streams in four aquatic regimes in terms of their influence over the development of aquatic life is updated from the existing classifications, with stream aquatic regimes defined as Permanent, Temporary-pools, Temporary-dry and Episodic. While aquatic regimes describe the long-term overall variability of the hydrological conditions of the river section and have been used for many years by hydrologists and ecologists, aquatic states describe the availability of mesohabitats in given periods that determine the presence of different biotic assemblages. This novel concept links hydrological and ecological conditions in a unique way. All these methods were implemented with data from eight temporary streams around the Mediterranean within the MIRAGE project. Their application was a precondition to assessing the ecological quality of these streams.

This paper presents the results of a study which characterizes the hydrological regime of a temporary river at reach scale and analyzes the hydrological alterations due to anthropogenic pressures using the SWAT model to estimate the daily streamflows and the periods without flow which would occur in natural conditions. The study area is the Salsola and Celone river basins, located in SE Italy. In a first part, we identified six classes of flow, the so-called Aquatic States (ASs), which play a major role in determining the available mesohabitats and subsequently the characteristics of the aquatic life. The monthly occurrence of the different ASs over a long period has been evaluated in order to provide useful information to design biological samplings. The results show that dry bed conditions can occur from May to January and arheic state from April to January in the reaches located in the upper part of the basin. The impacted river reaches showed a different behavior depending on the anthropogenic impacts. In a second part, two indicators based on the statistics of the periods without flows were used, monthly flow permanence and dry season predictability, for describing the flow regime components which may have been altered by anthropogenic pressures. The indexes, which were computed in impacted and natural conditions, were used as coordinates in a plot to obtain a graphical vision of the regimes. The distance between the points representing the actual (impacted) and natural states in the plot were used to classify the hydrological alterations.

In a catchmnent, nitrogen (N) export from terrestrial ecosystems to rivers is controlled by the hydrologicalprocesses and N balance. In the present paper, the soil system N budget and riverine exportwere quantified in a Mediterranean watershed, the Celone (South-East, Italy). The study area (72 km2)consists of agricultural land (70%) and deciduous forests with three small residential areas. Major Ninputs derived from fertilizers and animal manure, corresponding for the whole watershed area to 68and 12 kg N ha-1 yr-1, respectively. N input from point sources was 1% of total input and atmosphericdepositions measured in a gauging station near the study area was quantified in ~6 kg N ha-1 yr-1. CropN uptake was the main N output from agricultural land; it was estimated in ~37 kg N ha-1 yr-1 by usingdata on crop yields provided by local farmers. Total flux of N in surface water was quantified for a year atthe outlet of the study area by using continuous measures of flow and discrete measures of N concentrationscarried out with a different frequency during the normal and low flow and when floods occurred.The hydrological regime of the stream, which is a temporary river, plays an important role in N transport.Water quality was found to vary considerably through the year in terms of both nutrient concentrationsand loads. Riverine N export was quantified in 41% of total N input, and it was mainly transported duringflood events, ~60% of the annual load was delivered during floods occurred in 38 days. Organic nitrogenand nitrate were the main N forms in surface water, and the contribution per hectare was about24 and 14 kg N, respectively. On a yearly basis, the difference between N inputs and outputs includingriverine export was estimated in about 4 kg N ha-1 yr-1 for the whole watershed area. This amount partlyaccumulates in soils in different N forms and the remaining part, mainly in form of nitrate, percolatesthrough unsaturated soiltowards groundwater. This study reports an important analysis of N pollution ina Mediterranean watershed with a temporary river system and limited data availability. Data acquisitionand handling have proved to be an important challenge to overcome in N balance quantification. Theresults and the methodology of the present work can be useful for understanding nitrogen loss dynamicsand for functional water management and land use planning.

In this paper, we present an approach to evaluate the hydrological alterations of a temporary river. In theserivers, it is expected that anthropogenic pressures largely modify low-flow components of the flow regime with consequencesfor aquatic habitat and diversity in invertebrate species. First, by using a simple hydrological index (IARI) riversegments of the Celone stream (southern Italy) whose hydrological regime is significantly influenced by anthropogenicactivities have been identified. Hydrological alteration has been further classified through the analysis of two metrics: thedegree (Mf) and the predictability of dry flow conditions (Sd6). Measured streamflow data were used to calculate the metricsin present conditions (impacted). Given the lack of data from pristine conditions, simulated streamflow time serieswere used to calculate the metrics in reference conditions. The Soil and Water Assessment Tool (SWAT) model wasused to estimate daily natural streamflow. Hydrological alterations associated with water abstractions, point dischargesand the presence of a reservoir were assessed by comparing the metrics (Mf, Sd6) before and after the impacts. The resultsshow that the hydrological regime of the river segment located in the upper part of the basin is slightly altered, while theregime of the river segment downstream of the reservoir is heavily altered. This approach is intended for use with ecologicalmetrics in defining the water quality status and in planning streamflow management activities.

Agriculture is one of the main causes of water consumption and degradation. Assessing its sustainability is important to determining how the current use of water resources can affect their availability in the future and to safeguard their quantity and quality. In this context, this research was designed to develop a simple approach for the evaluation of agricultural sustainability, based on coupling the assessment of the total water footprint (WF) of catchment-scale crops and in-stream monitoring activities. The study focussed on a Mediterranean agricultural watershed (Celone, southeast Italy). Results for the study period (July 2010 June 2011) show the total WF to be 79.9 Mm(3) y(-1), subdivided into 30.3% green water, 0.5% blue water and 69.2% grey water, thus highlighting the importance of grey water in agricultural water use. The grey WF estimates are highly sensitive both to leaching and runoff fractions and applied water standards, and they are affected by large uncertainty. Tomato is the crop having the highest total crop water use (CWU), which is equal to 2521 mm (286 mm green CWU, 412 mm blue CWU, 1823 mm grey CWU). Legumes relied only on green water (217 mm green CWU). The sustainability assessment of present water consumption, subdivided into the three WF components, indicates sustainable use of green water, fluctuating sustainability of blue water resources, depending on the season and the environmental flow requirement, and unsustainable grey water production and water pollution level for the Celone River. The methodology employed in this paper could be useful in watershed planning and management, helping farmers and decision-makers choose suitable crops for locally sustainable water use. (C) 2018 Elsevier Ltd. All rights reserved.

A new approach, the 'Naturalness Status' (NS), is suggested to classify the hydrologic alteration of temporary rivers from natural conditions based on the Hydrological Status Tool (HS-Tool). The HS-Tool considers two metrics: the degree and the predictability of dry flow conditions for both natural flow and its alterations, at each water body in actual and natural conditions. The Soil andWater Assessment Tool (SWAT) model is simulating the river flow of Evrotas water bodies, Greece, under natural, actual and climate-impacted conditions. The majority of Evrotas water bodies (72%) experience good (low-impacted) NS for the examined period (1990-2010), despite their intermittent flow regime. Severe flow alteration is predicted for 57% of Evrotas water bodies (high-impacted NS), while selecting the KNMI-RACMO2 future climate projections scenario (2020-2060) as input into the SWAT model. Hydrologic extreme drought phenomena or anthropogenic pressures in water regime can be quantified by the NS. The method is intended to be used in basin decision-making analysis at fulfilling the Water Framework Directive goals.

Temporary streams are characterised by specific hydrological regimes, which influence ecosystem processes, groundwater and surface water interactions, sediment regime, nutrient delivery, water quality and ecological status. This paper presents a methodology to characterise and classify the regime of a temporary river in Southern Italy based on hydrological indicators (HIs) computed with long-term daily flow records. By using a principal component analysis (PCA), a set of non-redundant indices were identified describing the main characteristics of the hydrological regime in the study area. The indicators identified were the annual maximum 30- and 90-day mean (DH4 and DH5), the number of zero flow days (DL6), flow permanence (MF) and the 6-month seasonal predictability of dry periods (SD6). A methodology was also tested to estimate selected HIs in ungauged river reaches. Watershed characteristics such as catchment area, gauging station elevation, mean watershed slope, mean annual rainfall, land use, soil hydraulic conductivity and available water content were derived for each site. Selected indicators were then linked to the catchment characteristics using a regression analysis. Finally, MF and SD6 were used to classify the river reaches on the basis of their degree of intermittency. The methodology presented in this paper constitutes a useful tool for ecologists and water resource managers in the Water Framework Directive implementation process, which requires a characterisation of the hydrological regime and a 'river type' classification for all water bodies.

Rivers in the Mediterranean region often exhibit an intermittent character. An understanding and classification of the flowregimes of these rivers is needed, as flow patterns control both physicochemical and biological processes. This paper reports anattempt to classify flow regimes in Mediterranean rivers based on hydrological variables extracted from discharge time series.Long-term discharge records from 60 rivers within the Mediterranean region were analysed in order to classify the streams intodifferent flow regime groups. Hydrological indices (HIs) were derived for each stream and principal component analysis (PCA)and then applied to these indices to identify subsets of HIs describing the major sources of variations, while simultaneouslyminimizing redundancy. PCA was performed for two groups of streams (perennial and temporary) and for all streams combined.The results show that whereas perennial streams are mainly described by high-flow indices, temporary streams are described byduration, variability and predictability indices. Agglomerative cluster analysis based on HIs identified six groups of riversclassified according to differences in intermittency and variability. A methodology allowing such a classification for ungaugedcatchments was also tested. Broad-scale catchment characteristics based on digital elevation, climate, soil and land use data werederived for each long-term station where these data were available. By using stepwise multiple regression analysis, statisticallysignificant relationships were fitted, linking the three selected hydrological variables (mean annual number of zero-flow days,predictability and flashiness) to the catchment characteristics. The method provides a means of simplifying the complexity ofriver systems and is thus useful for river basin management.

The paper uses a simple water balance model that partitions the precipitation between actual evapotranspiration, quick flow and delayed flow, and has sufficient complexity to capture the essence of climate and vegetation controls on this partitioning. Using this model, monthly flow duration curves have been constructed from climate data across Europe to address the relative frequency of ecologically critical low flow stages in semi-arid rivers, when flow commonly persists only in disconnected pools in the river bed. The hydrological model is based on a dynamic partitioning of precipitation to estimate water available for evapotranspiration and plant growth and for residual runoff. The duration curve for monthly flows has then been analysed to give an estimate of bankfull flow based on recurrence interval. Arguing from observed ratios of cross-sectional areas at flood and low flows, hydraulic geometry suggests that disconnected flow under "pool" conditions is approximately 0.1 % of bankfull flow. Flow duration curves define a measure of bankfull discharge on the basis of frequency. The corresponding frequency for pools is then read from the duration curve, using this (0.1 %) ratio to estimate pool discharge from bank full discharge. The flow duration curve then provides an estimate of the frequency of poorly connected pool conditions, corresponding to this discharge, that constrain survival of river-dwelling arthropods and fish. The methodology has here been applied across Europe at 15 km resolution, and the potential is demonstrated for applying the methodology under alternative climatic scenarios.

In this work, a simple approach for calibrating the water footprint (WF) accounting of crops with in-streammeasurements at the catchment scale was developed. The green and blue components of the WF were evaluatedby performing a soil-water balance at a 10-day time-interval. The surface runoff was calibrated based oncontinuous streamflow measurements. Meanwhile, the grey component of the WF related to nitrogen use wasquantified by means of the results from the in-stream monitoring activities.The methodology can be applied to any catchment where soil, land use, weather, agricultural practices, nitrogenbalance and stream data are available. This methodological approach can support local authorities in thedecision-making process for effective agricultural policy setting and water planning. The WF accounting for an agricultural catchment is coupled with surface-water monitoring results The green and blue WF are assessed by performing a soil-water balance Surface runoff and grey water accounts are based on in-stream monitoring activities

The Merguellil catchment (central Tunisia) is a typical Mediterranean semi-arid basin, which suffers from regular water shortage aggravated by current droughts. Over recent decades, the continuous construction of small and large dams and soil and water conservation works (i.e. contour ridges) have taken place within this watershed. However, little is known about the effect of these water-harvesting systems on the water balance components of arid or semi-arid basins. In this paper, we present the results of a study, which evaluates the impact of the contour ridges on water balance components and erosion at basin scale by using the soil and water assessment tool model (SWAT). Large dams were modelled as reservoirs, small dams as ponds and contour ridges as potholes that fill with water and increase the percolation into the aquifer. The model predicts that contour ridges produce annually a reduction of 32 and 21% in surface run-off and river discharge, respectively, and an increase in aquifer recharge of 50%. At the same time, retention of a large proportion of entrained sediment (26%) was modelled.

In this presentation, the experience gained in the first experimental use in the UE (as far as we know) of theconcept and methodology of the "Total Maximum Daily Load" (TMDL) is reported. The TMDL is an instrumentrequired in the Clean Water Act in U.S.A for the management of water bodies classified impaired. The TMDLcalculates the maximum amount of a pollutant that a waterbody can receive and still safely meet water qualitystandards. It permits to establish a scientifically-based strategy on the regulation of the emission loads controlaccording to the characteristic of the watershed/basin.The implementation of the TMDL is a process analogous to the Programmes of Measures required by the WFD,the main difference being the analysis of the linkage between loads of different sources and the water quality ofwater bodies.The TMDL calculation was used in this study for the Candelaro River, a temporary Italian river, classified impairedin the first steps of the implementation of the WFD.A specific approach based on the "Load Duration Curves" was adopted for the calculation of nutrient TMDLsdue to the more robust approach specific for rivers featuring large changes in river flow compared to the classicapproach based on average long term flow conditions. This methodology permits to establish the maximumallowable loads across to the different flow conditions of a river.This methodology enabled: to evaluate the allowable loading of a water body; to identify the sources and estimatetheir loads; to estimate the total loading that the water bodies can receives meeting the water quality standardsestablished; to link the effects of point and diffuse sources on the water quality status and finally to individuate thereduction necessary for each type of sources.The loads reductions were calculated for nitrate, total phosphorus and ammonia.The simulated measures showed a remarkable ability to reduce the pollutants for the Candelaro River.The use of the Soil and Water Assessment Tool model (SWAT), was applied in order to obtain a daily flow andwater quality dataset of the Candelaro River for a longer period than the available measured data. The use of themodel permitted to obtain a robust assessment of the present and future water quality status overcoming the lackof measured data.The results highlighted the critical condition of water quality particularly during the dry/low flow periods andthe necessity to adopt specific measures for each flow conditions to restore the water surface quality status of theCandelaro River.

Information describing the hydrological regime is likely to play a major role in the implementation of the WFD across the EU. In fact, the flow regime is one of the drivers of the ecological status of a stream. The analysis of the hydrological regime is particularly important to understand the ecological status in intermittent rivers since the flow varies on spatial and temporal scale depending on precipitation patterns. A method for analysing the flow regime for intermittent rivers is proposed in order to help in the design of the schedule for biological samplings. Climatic data were used as a guide to hydrological regime and an analysis of daily flow data was done to define low flow and dry periods, extreme flow conditions and response to rainfall events.

The potential impacts of future climate scenarios on water balance and flow regime are presented and discussed for a temporary river system in southern Italy. Different climate projections for the future (2030-2059) and the recent conditions (1980-2009) were investigated. A hydrological model (SWAT) was used to simulate water balance at the basin scale and streamflow in a number of river sections under various climate change scenarios, based on different combinations of global and regional models (GCMs and RCMs). The impact on water balance components was quantified at the basin and sub-basin levels as deviation from the baseline (1980-2009), and the flow regime alteration under changing climate was estimated using a number of hydrological indicators (IHA). An increase in mean temperature for all months between 0.5-2.4°C and a reduction in precipitation (by 4-7%) was predicted for the future. As a consequence, a decline of blue water (7-18%) and total water yield (11-28%) was estimated. Although the river type classification remains unvaried, the flow regime distinctly moves towards drier conditions and the divergence from the current status increases in future scenarios, especially for those reaches classified as I-D (i.e. Intermittent-Dry) and E (Ephemeral). Hydrological indicators showed a decrease in both high flow and low flow magnitudes for various time durations, an extension of the dry season and an exacerbation of extreme low flow conditions. A reduction of snowfall in the mountainous part of the basin and an increase in potential evapotranspiration was also estimated (4-4.4%). Finally, the paper analyses the implications of the climate change for river ecosystems and for River Basin Management Planning. The defined quantitative estimates of water balance alteration could support the identification of priorities that should be addressed in upcoming years to set water-saving actions.

This study aims to evaluate the suitability of the Soil and Water Assessment Tool model insimulating runoff and sediment loss in the Carapelle (SE Italy), a typical Mediterranean watershed,where continuous measurements of streamflow and sediment concentration were collected overa 5-year period, on a half-hour timescale, processed on a daily timescale. After sensitivity analysis,the model was calibrated and validated for runoff and sediment. Statistics show generally satisfactoryefficiency. To further improve sediment simulation performance, we used a seasonal calibrationscheme, in which data recorded in the dry and wet seasons were used to calibratesediments separately, on a seasonal basis. We also tested the model's capability in identifyingthe major sediment source zones and river segments where there is sediment deposition. Onthe basin scale, the average water yield (186 mm) corresponds to 27% of the total rainfall(686 mm), and average annual sediment load was estimated to be 6.8 t ha-1 year-1. On thesubbasin scale, a gradient of sediment yield was found that is characterised by a large differenceamong the upper (7 to 13 t ha-1 year-1), central, and lower parts (<1 t ha-1 year-1) of the studyarea. Conversely, deposition in channel flow has its highest values in the central part of the watershed,where there is an alluvial plain. Winter wheat and olive land use are the major source areas,in terms of sediment. This study confirms that the Mediterranean watershed is a fragile ecosystem,and measures are needed to mitigate soil depletion.[object Object]

Sampling strategies and methods used for estimating load can lead to large uncertainties in suspended sedimenttransport quantification, especially in rivers with high variability in streamflow. The aim of this paper is toevaluate suspended sediment load, using a number of direct estimation techniques, in order to find a suitablemethod for temporary river systems and to assess the uncertainty associated with load estimation, due to thespecific method applied. One year of continuous measurement of flow, and discrete sampling (n=216) ofsuspended sediment concentrations, taken from 2010 to 2011 in the Celone River (SE, Italy), were used toestimate annual load. Averaging, ratio and regression estimator methods were applied to the entire dataset, andto subsets of data, to calculate the load. The results show a wide range of values, from 220 to 1123 t km-2 yr-1, withrespect to the applied suspended sediment load estimation techniques. Averaging methods resulted biased.Sediment rating curves underestimated load, while, if the back-transformation bias correction was used, loadwas overestimated. The ratio methods generally overestimate load. Increased precision and accuracy wasachieved through applying data stratification, based on flow regime and seasonality. After applying three differentflow regime stratifications, the annual load ranged from 240 to 606 t km-2 yr-1 and, using seasonalstratification, from 258 to 974 t km-2 yr-1. It seems that ratio estimator methods, and the regression equationsapplied to the stratification on a flow regime basis, are more suitable for estimating load in temporary, flashystreams.

The Celone River Basin (Puglia, Italy) is characterized by a diffuse pollution from agricultural sources. Like most intermittent rivers in the Mediterranean area, this stream is not well monitored; only few water quality data are available. Thus, due to high variability in streamflow and nutrient concentrations, which characterizes this type of rivers, it is difficult to estimate accurately nutrient loads from point and non point sources and consequently anthropogenic activities impact on the river. In this work, a detailed study was carried out on the Celone river to identify the chemical characteristics of the water and to quantify the annual nutrient loads delivered to the downstream reservoir. An automatic sampler and a flow module were set up in a section of the river. Continuous measures of flow were carried out using a different frequency for water sampling when floods occurred and during normal or low flow state. Nutrient concentrations in the water samples were accurately determined in laboratory. Water quality of the river was found to vary considerably along the year in,terms of nutrient concentration. Nitrate and total phosphorus are the main cause of water pollution. Nutrient losses by surface runoff were essentially a winter process. The contribution per hectare of non point sources can be estimate at about 39 kg/ha of total nitrogen and 2.4 kg/ha of total phosphorus. Estimates of loads in terms of TN and TP for the 21-day period of flood were calculated in 55 and 81% of annual loads, respectively. This study clearly demonstrates the importance of flood event contribution to the annual nutrient load.

in this work, a detailed study was carried out on the Celone river to quantify the nutrient loads delivered to the downstream reservoir on seasonal and annual time scale. An automatic sampler and a flow module were set up in a section of the river. Continuous measures of flow were carried out using a different frequency for water sampling when floods occurred and during normal or low flow state. Nutrient concentrations in the water samples were occurately determined in laboratory. Water quality of the river was found to vary considerably along the year in terms of nufrient concentration. Nitrate and total phosphorus are the moin cause of water pollution. Nutrient losses by surface runoff were essentially a winter process. The contribution per hectare of non poini sources can be estimoted at about 39 kg/ha of total nitrogen and 2.4 kg/ha of total phosphorus. Estimates of loads in terms of TN ond TP for the 21-day period of flood were calculated in 55 and 81 % of annual load, respectively.

The Rio Mannu River Basin (Sardinia, Italy) is undergoing a process of agricultural intensification. Like many Mediterranean areas, this basin is characterized by water shortages and diffuse pollution from agricultural sources. Hence the objective of this study was to develop possible land use and land management scenarios that could constitute an alternative to the current watershed management. Several land use and land management scenarios were formulated and analyzed with local stakeholders, and two were selected and simulated as realistic in consideration of the socio-economical aspects of the study area. Scenario I involves agricultural practices that include a reduction in fertilizer use to meet the Water Framework Directive requirements for "good" status of water bodies. Scenario 2 introduces rapeseed cultivation, replacing durum wheat in a small area, to investigate the impact of biofuel plant cultivation on water quality. Each option was assessed by considering the effects on water quality, crop yields and economic benefits. The Soil and Water Assessment Tool (SWAT) model was applied to simulate hydrological processes and evaluate current and future nutrient loads. This model requires adequate streamflow data for calibration and validation. However, as is the case for many Mediterranean basins, insufficient data were available. Therefore, a methodology was developed and tested to calibrate hydrological processes based on the transposition of a parameter set from a gauged catchment located in the same region. This study suggests that a sound use of fertilizers could substantially reduce the amount of nutrients flowing into surface waters, although the effects of such a policy on crop yield and farm income would be negative in some cases. Moreover, the results clearly predict that the replacement of durum wheat with rapeseed (a biofuel crop), could offer a margin of profit, but would have a negative impact on water quality due to increased nutrient losses. Consequently, this option is unsuitable for this area. Furthermore, it can be inferred from these results that the promotion of the use of energy from renewable sources may have a negative impact on the objectives of the EU Water Framework Directive. Clearly, this process needs to be regulated, taking into account environmental and socio-economical aspects. (C) 2011 Elsevier Ltd. All rights reserved.

During the last decades, the Mediterranean region is suffering more and more from droughts. It has been recognized as one of the most vulnerable regions in the world to climate change. Understanding the impact of climate change on various components of water cycle is an important challenge for long-term sustainable management of water resources. In this paper, the integrated hydrological model "Soil and Water Assessment Tool" (SWAT 2005) was used to study the impact of future climate on water resources of a Mediterranean catchment. Future climate scenarios for periods of 2010-2039 and 2070-2099 were generated from the Canadian Global Coupled model (CGCM 3.1) for scenarios A1B, B1, and A2. These CGCMs data were then statistically downscaled to generate future possible local meteorological data of precipitation and temperature in the study area. SWAT model was run first under current climate (1986-2005) and then for the future climate period to analyze the potential impact of climate change on flow, evapotranspiration, and soil moisture across this catchment. Finally, Richter et al.'s Indicators of Hydrologic Alteration (IHA) were used to analyze the flow regime alterations under changing climate. The main results indicate that this catchment would suffer a combination of increased temperature and reduced rainfall that will reduce water resources in this area. Consequently, summer droughts would be intensified. Different spatial responses to climate change were observed in the catchment for near future simulations. Higher altitude regions would experience an increase of the total water yield, while a reduction is foreseen for lower parts. For far future, a noticeable decrease would affect water resources in all part of the catchment.

The Rio Mannu River Basin (Sardegna Island, Italy) is experiencing an intensification of agriculture, and correspondingly, irrigation areas are increasing. Like many Mediterranean areas, this basin is characterized by water shortage and diffuse pollution from agricultural sources. It is than important to design, evaluate and adopt adequate management policies to prevent further water quality impairment. The Soil and Water Assessment Tool (SWAT), a model for agricultural watersheds, was applied to simulate hydrological processes and evaluate current and future nutrient loads. An alternative scenario that assumes a reduction in fertilizer was simulated. This option was assessed by considering the effects on water balance, water quality, crop yields and economic benefits. The model was able to simulate the hydrologic cycle and water quality, notwithstanding an insufficient availability of measured data. This study suggests that a better use of fertilizers could substantially reduce the amount of nutrients flowing into surface waters, even though the effects of such a policy on crop yield and farm income are in some cases negative.

The Rio Mannu River Basin (Sardinia, Italy) is experiencing an intensification of agriculture, and correspondingly, irrigation areas are increasing. Like many Mediterranean areas, this basin is characterized by water shortages and diffuse pollution from agricultural sources. It is than important to design, evaluate and adopt adequate management policies to prevent further water quality impairment. The Soil and Water Assessment Tool (SWAT), a model for agricultural watersheds, was applied to simulate hydrological processes and evaluate current and future nutrient loads. Several alternative scenarios were developed through discussions with stakeholders, and four of them were selected and simulated as realistic in consideration of the socio-economical situation in the study area. Scenario A involves agricultural practices that assume a reduction in fertilizer. Scenario B regards the reuse (in three sub-basins) of treated wastewater in fert-irrigation of olive trees instead of discharging it into the river system. Scenario C regards the partial substitution of durum wheat with sugar beet in a subset of the catchment. Scenario D introduces rapeseed and sunflower replacing durum wheat in an other small area. We assessed each option by considering the effects on water balance, water quality, crop yields and economic benefits. The model was able to simulate the hydrologic cycle and water quality notwithstanding an insufficient availability of measured data. This study suggests that a better use of fertilizers could substantially reduce the amount of nutrients flowing into surface waters, but the effects of such a policy on crop yield and farm income are in some cases negative. The reuse of treated effluent can results in a moderate reduction in nutrient load but in a larger reduction in nutrient concentration; it is more efficient in summertime and on soluble compounds (NO3, NH3 and min P); furthermore an application at larger scale of such scenario will result in very great results. The sugar beet scenario is the less competitive scenario: it features slightly higher loads and large increment in water resources usage. In the last scenario the release of several nutrient will increase; maybe a competitive scenario in terms of revenues for farmers coupled with a 6% reduction of water use in irrigation.

In this study, the simulations generated by two of the most widely used hydrological basin-scale models, theAnnualized Agricultural Non-Point Source (AnnAGNPS) and the Soil and Water Assessment Tool (SWAT), werecompared in a Mediterranean watershed, the Carapelle (Apulia, Southern Italy). Input data requirements, timeand efforts needed for input preparation, strength and weakness points of each model, ease of use and limitationswere evaluated in order to give information to users. Models were calibrated and validated at monthly time scalefor hydrology and sediment load using a four year period of observations (streamflow and suspended sedimentconcentrations). In the driest year, the specific sediment load measured at the outlet was 0.89 t ha-1 yr-1, whilethe simulated values were 0.83 t ha-1 yr-1 and 1.99 t ha-1 yr-1 for SWAT and AnnAGNPS, respectively. In thewettest year, the specific measured sediment load was 7.45 t ha-1 yr-1, and the simulated values were8.27 t ha-1 yr-1 and 6.23 t ha-1 yr-1 for SWAT and AnnAGNPS, respectively. Both models showed from fair toa very good correlation between observed and simulated streamflow and satisfactory for sediment load. Resultsshowed that most of the basin is under moderate (1.4-10 t ha-1 yr-1) and high-risk erosion (> 10 t ha-1 yr-1).The sediment yield predicted by the SWAT and AnnAGNPS models were compared with estimates of soil erosionsimulated by models for Europe (PESERA and RUSLE2015). The average gross erosion estimated by theRUSLE2015 model (12.5 t ha-1 yr-1) resulted comparable with the average specific sediment yield estimated bySWAT (8.8 t ha-1 yr-1) and AnnAGNPS (5.6 t ha-1 yr-1), while it was found that the average soil erosionestimated by PESERA is lower than the other estimates (1.2 t ha-1 yr-1).

In the Mediterranean regions, hydrologic processes are quite specific due to the temporal variability of precipitation characterized by a succession of drought and flash-flood periods. These processes may also have changed due to a range of human activities such as land use changes, dams building, soil and water conservations works. The Merguellil catchment (Central Tunisia) is a typical Mediterranean semi-arid basin which suffers regular water shortage aggravated by current drought. During the recent decades the continuous construction of small and large dams and Soil and Water Conservation Works (SWCW) (ie. Counter ridges) has taken place within the watershed. However, little is known about the effect of these water harvesting systems on the water balance components of arid watersheds. The work presented here attempts to simulate the actual water balance using the Soil and Water Assessment Tool (SWAT-2005) model including the water harvesting systems. Large dams are modeled as reservoirs, small dams as ponds, and contour ridges as potholes that fill with water, and increase the percolation into the aquifer. The model was rather successful in reproducing water flow. Two scenarios were further generated. The first one regards the removal of contour ridges to assess their impact to water and sediment load. The second scenario consists in planting the olive trees between contours. The results of the first scenario show that the contour ridges contribute to the retention of high quantity of sediment. These regulations reduce the surface runoff by 32 %.The second scenario shows that planting the olive trees between contours could improve its yield.

As most of the rural areas inMediterraneanRegion,the Celone river basin (Apulia, Italy) is characterized by diffusepollution from agriculture. Nutrient export from terrestrialecosystem to the river is controlled by hydrologicalprocesses and nutrient input frompoint and non-point sources.In the present paper, anthropogenic nitrogen input and theriverine export of nitrate-N (N-NO3) were quantified throughseveral survey campaigns, continuousmeasures of streamflowand discrete determinations of concentrations. A differentfrequency for water sampling was used, respectively, duringfloods and during normal- or low-flow state. Nitrate-N concentrationsin surface waters were found to vary considerablyacross the seasons. The riverine N-NO3 export was estimatedto be about 14 kg N ha-1 year-1. Major N inputs derivedfrom fertilizers and animal manure correspond to 68.2 and24 kg N ha-1 year-1, respectively. Nitrate-N fluxes instreamduring flood events (21 days) accounted for about 63%of the annual loading. This study clearly demonstrates theimportance of flood event contributions to the annual nutrientloading delivered to the reservoir and that more efficient fertilizersand management practices are needed to reduce Ninput.

Non-perennial rivers and streams (NPRS) cover > 50% of the global river network. They are particularly predominant in Mediterranean Europe as a result of dry climate conditions, climate change and land use development. Historically, both scientists and policy makers underestimated the importance of NRPS for nature and humans alike, mainly because they have been considered as systems of low ecological and economic value. During the past decades, diminishing water resources have increased the spatial and temporal extent of artificial NPRS as well as their exposure to multiple stressors, which threatening their ecological integrity, biodiversity and ecosystem services. In this paper, we provide a comprehensive overview of the structural and functional characteristics of NPRS in the European Mediterranean, and discuss gaps and problems in their management, concerning their typology, ecological assessment, legislative and policy protection, and incorporation in River Basin Management Plans. Because NPRS comprise highly unstable ecosystems, with strong and often unpredictable temporal and spatial variability - at least as far as it is possible to assess - we outline the future research needs required to better understand, manage and conserve them as highly valuable and sensitive ecosystems. Efficient collaborative activities among multidisciplinary research groups aiming to create innovative knowledge, water managers and policy makers are urgently needed in order to establish an appropriate methodological and legislative background. The incorporation of NPRS in EU-Med River Basin Management Plans in combination with the application of ecological flows is a first step towards enhancing NPRS management and conservation in order to effectively safeguard these highly valuable albeit threatened ecosystems.

Hydrological indicators (HIs) are commonly used in eco-hydrological studies (i.e. environmental flow and hydrological status assessment). Their computation is based on streamflow data, and if measured data are not available, hydrological models can be used to generate flow data. The present paper describes a study that aimed to predict streamflow in a temporary river and to analyze the general reliability of some hydrological indicators evaluated by using simulated data instead of measured flow data. The SWAT model was used to predict daily streamflow in a river section of the Celone river (Puglia, Italy). Several HIs characterizing the patterns of river flow or specific hydrological components were evaluated using observed and simulated streamflow. The results show that the SWAT model is able to simulate streamflow in temporary river systems, but its performance under extreme low flow conditions may be a weak point. When simulated streamflow time series were used, the replicability of the HIs evaluated using a rigorous statistical methodology ranged from good to limited. Good performance was found for the magnitude of discharge in wet months (average monthly flow from November to May), for the high flow indicators (annual maxima, 1-, 3-, 7-, 30-, 90-day mean flow) and timing, while limited performance was detected for low flow indicators (annual minimum 1-, 3-, 7-, 30-, 90-day mean flow) and the number of zero flow days. Better performance for low flow indicators was found after introducing the zero-flow threshold. This type of eco-hydrological study may contribute to characterizing the flow regime and its alterations in regions with scarce data.

Two sets of soil lysimeters were amended with solid and liquid olive mill wastes and the composition ofleachate was analysed. Five treatments were carried out using: olive mill wastewater (OMW) at twodifferent rates (80 and 320 m3/ha); OMW pre-treated by catalytical digestion with MnO2; compost obtainedby exhausted olive pomace; freshwater as the control. Electric conductivity, pH, potassium, totalpolyphenols and nitrates were monitored in the leachate as indexes of potential groundwater contamination.The study demonstrated that the impact of all the selected amendments on groundwater was theminimum. OMW was safely applied to soil even at four times the rate allowed by the Italian law, and pretreatmentby catalytical digestion was not necessary to further reduce the impact on groundwater. Theapplication of olive pomace compost was equally safe.

In the Mediterranean region suspended sediment transport is the predominant process in sediment export in most river basins. The aim of this paper is to analyze suspended sediment variability over a period of 12 months in the Celone river, a temporary river located in the Puglia region (SE-Italy), and to evaluate sediment rating curves for estimating suspended sediment concentrations for subsequent load calculations. Similarly to most temporary rivers, the Celone river shows relevant differences among mean daily flows and the extreme instan-taneous flows during floods. To take into account these peculiarities, the rating curves were developed as a func-tion of hydrological conditions: high, normal and low flows. Continuous measures of streamflow and frequent samplings of suspended solid concentrations (SSCs) during flood events, normal flow and low flow were used. The plot of the SSC against discharge takes the form of a hysteresis loop. Clockwise, anticlockwise and mixed-shaped loops were observed. Suspended sediment yield was found to be in the range of 250-384 t km -2 y -1 . The results show that about 94% of the total suspended materials were transported during the high flow regime, while less than 0.1% were under low flow conditions. Moreover, it was observed that 90% of the total annual suspended loads were moved between November to May. Flash floods that occur in summer exhibit the highest values of SSC. The proposed method, which was based on sediment rating curves, has proved to be valuable to generate SSC data for high and normal flows although it tends to underestimate the highest values. It can repre-sent a useful tool for water resource managers who need a quick and inexpensive method, specific for temporary rivers, to evaluate suspended sediment yield.

The evaluation of the "Hydrological Status" (HS) of a water body in a catchment is of the greatest importance in order to achieve the final objective of the European Water Framework Directive (WFD). It represents the distance of the actual hydrological regime from its natural condition and it may be responsible for the ecological status of a river. The WFD doesn't provide specific guidelines or recommendations on how the alterations should be evaluated and quantified. In this paper a new approach to evaluate the Hydrological Status of a temporary river was tested. The flow regime of a river has been classified through the analysis of two metrics: the degree and the predictability of dry flow conditions which were evaluated on monthly streamflow data. Both indeces were also used as indicators to assess the river's natural flow regime and its alterations. This method was applied to the Candelaro river basin (Puglia, Italy) where we had to face the problem of limited data availability. The SWAT model was used when streamflow data were not available, and a GIS procedure was applied to estimate potential water abstractions from the river. Four types of rivers were identified whose regimes may exert a control on the aquatic life. By using the two metrics as coordinates in a plot a graphic representation of the regime can be visualized in a point. Hydrological perturbations associated with water abstractions, point discharges and the presence of a reservoir were assessed by comparing the position of the two points representing the regime before and after the impacts. The method is intended to be used with other biological metrics in order to defining the ecological status of a stream. It is a useful tool when identifying river bodies under hydrological pressures and it can be used in planning the "measures" towards the WFD goals.

In achieving the final objective of the European Water Framework Directive, the evaluation of the 'hydrological status' of a water body in a catchment is of the utmost importance. It represents the divergence of the actual hydrological regime from its 'natural' condition and may thus provide crucial information about the ecological status of a river. In this paper, a new approach in evaluating the hydrological status of a temporary river was tested. The flow regime of a river has been classified through the analysis of two metrics: the permanence of flow and the predictability of no-flow conditions that were evaluated on monthly streamflow data. This method was applied to the Candelaro river basin (Puglia, Italy) where we had to face the problem of limited data availability. The Soil and Water Assessment Tool model was used when streamflow data were not available, and a geographic information system procedure was applied to estimate potential water abstractions from the river. Four types of rivers were identified whose regimes may exert a control on aquatic life. By using the two metrics as coordinates in a plot, a graphic representation of the regime can be visualized in a point. Hydrological perturbations associated with water abstractions, point discharges and the presence of a reservoir were assessed by comparing the position of the two points representing the regime before and after the impacts. The method is intended to be used with biological metrics in order to define the ecological status of a stream, and it could also be used in planning the 'measures' aimed at fulfilling the Water Framework Directive goals. © 2014 John Wiley & Sons, Ltd.

The assessment of the ecological status of water bodies, as requires by the European Water Framework Directive, can raise a number of problems when applied to temporary streams. These problems are because of the particular physical, chemical and biological conditions resulting from the recurrent cessation of flow or even the complete drying of the stream beds. In such non-permanent water bodies, the reference quality standards developed for permanent streams may only be applicable under certain circumstances or may not be applicable at all. Work conducted within the collaborative EU-funded project Mediterranean Intermittent River ManAGEment (MIRAGE) has addressed most of these difficulties and has used diverse approaches to solve them. These approaches have been brought together in the so-called MIRAGE Toolbox. This toolbox consists of a series of methodologies that are designed to be used in a sequential manner to allow the establishment of the ecological and chemical status of temporary streams and to relate these findings to the hydrological status of the streams. The toolbox is intended to serve the following purposes: (i) the determination of the hydrological regime of the stream; (ii) the design of adequate schedules for biological and chemical sampling according to the aquatic state of the stream; (iii) the fulfillment of criteria for designing reference condition stations; (iv) the analysis of hydrological modifications of the stream regime (with the definition of the hydrological status); and (v) the development of new methods to measure the ecological status (including structural and functional methods) and chemical status when the stream's hydrological conditions are far from those in permanent streams.

In 2011, the European Council stressed the significance of water quality for sustainable development in Europe and emphasized the need for better integration of the water policy objectives into the Common Agriculture Policy reform in rural areas. Since 2000, the Water Framework Directive (WFD) has required the EU Member States to target good ecological status for their water bodies. However, the implementation of the Directive for the numerous Mediterranean temporary streams has been delayed indicating the need for elaboration of the tools and methods that address the special characteristics of such water bodies. This requirement has been addressed by the recently completed MIRAGE project. In the context of the recent publication of the European Commission's Blueprint to Safeguard Europe's Waters, the MIRAGE-proposed framework for the characterization of the eco-hydrological dynamics and the systematic description of the measured impact for temporary rivers could bring considerable added value to the EU revision of all relevant water policies. The project recommends additions to WFD articles including an explicit definition of temporary rivers, adaptation of environmental objectives to their peculiarities and establishment of a proper method to determine the initial status and specific actions in River Basin Management Plans.

oIl confronto tra differenti metodologie di calcolo per la stima dei carichi di solidi in sospensione in un bacino idrografico del Mediterraneo mostra rilevanti differenze ne i valori dei carichi annuali.oL'estensione e la rappresentatività del set di dati utilizzati si è rivelata estremamente importante nella stima dei carichi di solidi in sospensione in un fiume a carattere temporaneo.oLa "stratificazione" dei dati si è dimostrata uno strumento efficace nella riduzione della perdita di accuratezza delle stime.

In the Mediterranean region, suspended sediment transport is the predominant process of material removaland sediment transport. The aim of this paper is to analyze the sediment dynamics and to compare differentcalculation methods in order to identify the most suitable for temporary rivers. At this purpose, continuousmeasurements of the flow and discrete values of sediment concentrations recorded from 2010 to 2011 havebeen used. Sampling was carried out with different frequencies as a function of the flow conditions. Severalcalculation methods were compared: Averaging Estimator Methods, Ratio Estimator Methods e RegressionEstimator Methods. The suspended sediment load was estimated in the range of 141-1123 tkm-2yr-1. Applyinga flow regime Stratification based on a flow exceeded frequency (f1<20%; 20%<f2<80%; f3>80%),the range of values was found in a restricted interval 298-595 tkm-2yr-1. Results show that the stratificationapproach is necessary methodology in load fluxes estimation in temporary rivers.

The estimation of existing nutrients load in a river is often challenging due to scarcity of measured data. In this case the use of a computer model is really helpful to assess the water quantity and nutrient balance of a water body, particularly in watershed affected by water pollution. The study watershed is the Candelaro River basin located in Italy, in a Mediterranean environment, that shows the typical hydrologic behavior of an intermittent river. The intensive agricultural activity is the main human pressure in the area. The flow gage measures are not available for a long time serie. The water quality monitoring activities carried out in order to classify the water quality of Candelaro River, in view of the development of a River Basin Management Plan, started on 2000 with monthly samples. The results of these activities, conducted only during the normal flow, showed that the water body often exceeds the limits of ammonia and P tot suitable for aquatic life. In order to achieve the objective of "good" status required by the Water Framework Directive (EU WFD 2000/60) different measures has been suggested to be adopted by the River Basin Authority in the "Regional Water Protection Plan". The different nutrient loads sources and the effectiveness of suggested measures included the application of BMPs in the agricultural area, have not been evaluated in the above mentioned Plan. In this study the SWAT model (Soil and Water Asessment Tool) has been applied to evaluate the contribution of different sources to the actual water quality of Candelaro River during the different hydrologic conditions. The effectiveness of different BMPs adoption in the agricultural areas has been assesed after the simulation of different scenarios.