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The objective of this study was to analyze the influence of climate change on the flow duration curves of five small rural catchments in the Amazon, as well as the hydroelectric power duration curves of micro hydroelectric power plants (MHPs) which can be implemented in the respective hydroelectric sites. The scenarios used were RCP 4.5 and RCP 8.5, defined during the 5th IPCC Report; these are the main optimistic and realistic greenhouse gas emission scenarios in the future. They projected on the flow duration curves of the small catchments under study and, consequently, on the hydroelectric power duration curves. Future precipitation was obtained via the PROJETA platform. For the simulation of flow duration curves, a rainfall-runoff model was used. The determination of the power duration curves was considered with the observed and simulated flow duration curves and with design parameters available in the literature. Based on the simulations, the reduction of high duration flows (minimum flows) was verified for the future scenarios studied, mainly for RCP 8.5, reflecting directly in the reduction of the hydro energetic potential of the analyzed rural catchments.

Flow duration curves (FDCs) that represent streamflow regime function through an empirical relationship between the FDC parameters and basin descriptors are widely adopted for hydrologic applications. However, the applications of this method are highly dependent on the availability of observation data. Hence, it is still of great significance to explore the process controls of underpinning regional patterns on streamflow regimes. In this study, we developed a new regionalization method of FDCs to solve the problem of runoff prediction for ungauged mountainous basins. Five empirical equations (power, exponential, logarithmic, quadratic, and cubic) were used to fit the observed FDCs in the 64 mountainous basins in eastern China, and the power model outperforms other models. Stepwise regression was used to explore the differentiated control of 23 basin descriptors on the 13 percentile flows of FDCs, and seven descriptors remained as independent variables for further developing the regional FDCs. Application results with different combinations of these selected descriptors showed that five indices, i.e., average annual rainfall (P), average elevation (H), average gradient (β), average topographic index (TI), and maximum 7d of annual rainfall (Max7d), were the main control factors of FDCs in these areas. Through the regional method, we found that 95.31% of all the basins have NSE values greater than 0.60 and ε (namely the relative mean square error) values less than 20%. In conclusion, our study can guide runoff predictions to help manage booming demands for water resources and hydropower developments in mountainous areas.

Ugandan rivers are being tapped as a resource for the generation of hydropower in addition to other uses. Studies on the reliability of these hydropower plants due to climate and land-use/land cover changes on the hydrology of these rivers are scanty. Therefore, this study aimed to model the impact of the changing climate and land-use/cover on hydropower reliability to aid proper planning and management. The hydropower reliability of Muzizi River catchment was determined from its past (1998–2010) and midcentury (2041–2060) discharge at 30 and 95% exceedance probability under Representative Concentration Pathways (RCPs) of 4.5 and 8.5, respectively. The past and projected hydropower were compared to determine how future climate and land-use changes will impact the discharge and hydropower reliability of Muzizi River catchment. Six LULC scenarios (deforestation, 31–20%; grassland, 19–3%; cropland, 50–77%; water bodies, 0.02–0.01%; settlement, 0.23–0.37%, and Barren land 0.055–0.046% between 2014 and 2060) and three downscaled Regional Climate Model (REMO and RCA4 for precipitation and RACMO22T for temperature from a pool of four CORDEX (Coordinated Regional Climate Downscaling Experiment) Africa RCMs) were examined. A calibrated SWAT simulation model was applied for the midcentury (2041–2060) period, and a potential change in hydropower energy in reference to mean daily flow (designflow ≥ 30% exceedance probability), firm flow (flow ≥ 95% exceedance probability), and mean annual flow was evaluated under the condition of altered runoff under RCP4.5 and RCP8.5 climate change scenarios for an average of REMO and RCA4 RCM. The future land use (2060) was projected using the MOLUSCE (Module for Land Use Change Evaluation) plugin in QGIS using CA-ANN. Three scenarios have been described in this study, including LULC change, climate change, and combined (climate and LULC change). The results suggest that there will be a significant increase in annual hydropower generation capacity (from 386.27 and 488.1 GWh to 867.82 and 862.53 GWh under RCP4.5 and RCP8.5, respectively) for the combined future effect of climate and land-use/cover changes. Energy utilities need to put in place mechanisms to effectively manage, operate, and maintain the hydropower plant amidst climate and land-use change impacts, to ensure reliability at all times. HIGHLIGHTS Innovative approaches for hydrological modeling in data-scarce scenarios.; The possibility to utilize bias-corrected reanalysis and historical discharge data to build a climate model in data-scarce scenarios.; Sheds light on the potential risks of land-use and climate change on hydropower reliability in data scarcity areas.; Informs the need to implement prudent catchment management practices and develop policies.

The Flow Duration Curve (FDC) set up at a specific site has a key role to the knowledge of the streamflow characteristic at that site. The FDC gives information on the water regime providing important information to optimally manage the water resources of the river. Spite of its importance, because of the lack of streamflow gauging stations, the FDC construction can be a not straightforward task. In ungauged or partially gauged catchments, FDCs are usually built using regionalization methods among the others. In this paper we show that the FDC is not a characteristic of the basin only, but of both the basin and the weather. Different weather conditions lead to different FDC for the same catchment. The differences can often be significant. Similarly, the FDC built at a site for a specific period of time cannot be used to retrieve the FDC at a different site for the same time window. In this paper we propose a new methodology to estimate FDCs at partially gauged basins (i.e., target sites) using discharge and precipitation data gauged at another catchment (i.e., reference catchment). The main idea is that it is possible to retrieve the FDC of a target period of time using the data gauged during a given reference time period for which data are available at both target and reference sites. To test the methodology, several reference and target time periods are analysed and results are shown for two different case study areas. The comparison between estimated and actually observed FDCs show the reasonability of the approach especially for intermediate percentiles.

The Atrato river basin is located in the Pacific fringe of Colombia, region with one of the highest precipitation rates in the world. The main purpose of this study is to determine the dominant processes in the hydrological responses along 17 sub-basins within the basin using principal component analysis. Watersheds located at the headwater presented a fast or medium response to the precipitation events, while higher flow homogeneity was observed in watersheds located at the lower portions of the basin. Three principal components were responsible for explaining 85.18% of the total variance. The component PC1 revealed the largest contributions for low flow behavior, being associated to precipitation, characteristic discharge values, compactness index, soil coverage and soil coarse textures. The component PC2 was assigned to the geological variables, fine and average texture soil and the average basin slope. Finally, the component PC3 has shown to be related to high flow patterns (maximum characteristic discharge values Q5 and Q1), igneous rocks and length of the basin. Highest specific discharge was associated to alluvial deposits and forest cover, whereas the slope was considered determinant for the run-off generation. RESUMO A bacia do Rio Atrato está situada na costa Pacífica da Colômbia, região que apresenta uma das maiores taxas de precipitação no mundo. O principal objetivo desse estudo foi o de determinar os processos dominantes nas respostas hidrológicas de 17 sub-bacias situadas na bacia do Rio Atrato pela aplicação da análise das componentes principais (ACP). As sub-bacias localizadas nas cabeceiras do Rio Atrato apresentaram tempos de resposta médios/rápidos em relação aos eventos de precipitação, enquanto um fluxo bastante homogêneo foi observado nas bacias localizadas na porção baixa da Bacia. Três componentes principais explicam 85,18% da variância total. A componente principal CP1 está associado às contribuições para as baixas vazões, precipitação índice de compacidade e texturas finas e grossas do solo, A CP2 associado as variáveis fisiográficas relacionadas ao arcabouço geológico e as texturas finas e a CP 3 associado ao padrão das altas vazões Q5 e Q1 assim como a extensão da bacia. As maiores descargas específicas estão associadas a presença de depósitos aluviais e a cobertura florestal nas porções baixas da Bacia, enquanto as áreas montanhosas determinam a geração do fluxo superficial.

Hydrologic models driven by downscaled meteorologic data from general circulation models (GCM) should be evaluated using long-term simulations over a historical period. However, simulations driven by GCM data cannot be directly evaluated using observed flows, and the confidence in the results can be relatively low. The objectives of this paper were to bias correct simulated stream flows from calibrated hydrologic models for two basins in New Jersey, USA, and evaluate model performance in comparison to uncorrected simulations. Then, we used stream flow bias correction and flow duration curves (FDCs) to evaluate and assess simulations driven by statistically downscaled GCMs for the historical period and the future time slices 2041&ndash, 2070 and 2071&ndash, 2099. Bias correction of stream flow from simulations increased confidence in the performance of two previously calibrated hydrologic models. Results indicated there was no difference in projected FDCs for uncorrected and bias-corrected flows in one basin, while this was not the case in the second basin. This result provided greater confidence in projected stream flow changes in the former basin and implied more uncertainty in projected stream flows in the latter. Applications in water resources can use the methods described to evaluate the performance of GCM-driven simulations and assess the potential impacts of climate change with an appropriate level of confidence in the model results.

Su kaynakları çalışmalarında özellikle biriktirmesiz hidroelektrik tesislerinde, su alma yapılarında ve su kalitesi ile ilgili çalışmalarda kullanılan debi-süreklilik eğrisi (DSE), bir akarsuda debi ile bu debinin belli bir periyotta eşitlendiği veya aşıldığı zaman yüzdesini gösteren grafiktir. Bu çalışmada, Türkiye'nin batısında yer alan Gediz Havzasındaki önemli akarsuların debi süreklilik eğrileri (DSE) ele alınmıştır. Bu kapsamda önce günlük ve aylık debilerden elde edilen DSE'ler karşılaştırılmıştır. Daha sonra kuruyan akarsularda sağlıklı sonuçlar veren Yıllık Yüzdeler metoduyla DSE'ler elde edilmiştir. Son olarak da debi süreklilik eğrilerindeki belli olasılıklı debilerin (Q0,5, Q0,50, Q0,95) önemli havza büyüklükleriyle değişimi irdelenmiştir. Çalışmayla, günlük ve aylık debi süreklilik eğrilerinin karşılaştırılması sonucunda söz konusu bu eğrilerin hemen hemen çakıştığı, dolayısıyla günlük akım verisi eksik olan veya bulunamayan akarsularda debi süreklilik eğrilerinin aylık akımlardan da elde edilebileceği gösterilmiştir. Daha sonra elde edilen DSE'lerin %5, %50 ve %95 aşılma olasılıklarına karşılık gelen akım değerlerinin havzanın en önemli özelliklerini ifade eden ortalama eğim, ortalama yükseklik ve yağış alanı büyüklükleriyle güçlü regresyon ilişkisine (R2%5=0,987, R2%50=0,988, R2%95=0,969) sahip olduğu saptanmıştır. Böylelikle özellikle akım ölçümü yapılamayan veya eksik verisi bulunan havzalarda belli olasılıklı (%5, %50 ve %95 gibi) akımların, havza ortalama eğimi, havza ortalama yüksekliği ve yağış alanı ile başarılı bir şekilde tahmin edilebileceği gösterilmiştir., The flow duration curve (FDC) used in water resources studies (such as water supply structures, water intake structures and water quality studies) is the graph showing the percentage of the flow rate in a stream versus the flow equalized or exceeded in a certain period. In this study, flow duration curve (FDC) of the major rivers in Gediz Basin, located in the west of Turkey, is discussed. Within this scope, the FDCs obtained from daily and monthly flows were compared at first. Subsequently, FDCs were obtained by using the Annual Percentages method, which gave healthy results in the dried rivers. Finally, the variation of the flow rates (Q0,05, Q0,50, Q0,95) with significant watershed sizes was investigated. As a result of comparison of daily and monthly flow duration curves, it has been shown that these curves are almost overlapping, so that flow duration curves can be obtained from monthly flows in streams with missing daily flow data. The flow values corresponding to 5%, 50% and 95% exceedances obtained from the FDCs show a strong regression relation (R2%5=0,987, R2%50=0,988, R2%95=0,969) with the mean slope, average elevation and precipitation area expressing the most important characteristics of the basin. Thus, it has been shown that the flows of a certain probability (5%, 50% and 95%) can be estimated successfully with basin mean slope, basin average height and precipitation area.

Mountain regions are considered to be the natural "water towers" of the world due to their importance as sources of many rivers. Reliable tools to estimate the availability and variability of streamflows in such regions are still rare. In this context, the present Thesis proposes to extend an existing Flow Duration Curve (FDC) modelling framework to Alpine environment. FDCs can be obtained empirically or based on models. Process-based FDC models have the advantage of incorporating hydrological process knowledge and thereby allowing the prediction of FDCs under changing conditions. This Thesis studies a simple process-based model that describes daily streamflow distributions as the result of subsurface flow pulses triggered by stochastic rainfall and censored by the soil moisture dynamics. The resulting streamflow distribution is characterized by only a few parameters: the mean rainfall depth and the frequency of events that produce discharge and recession parameters. The objective of this Thesis is the extension of the existing framework (Botter et al, 2007) for pluvial streamflow regimes to Alpine environments where the accumulation of water in the form of snow and ice influences the streamflow regime. The selected study region is Switzerland, an Alpine country with a wide range of hydro-climatologic conditions. The key of the extension of the model framework is a seasonal approach, i.e., a model set up for each of the up to three distinct seasons encountered in Alpine environments: i) pluvial season, ii) accumulation season, and iii) melting season. The pluvial season can be modelled by the original model framework, but required the definition of more robust parameter estimation methods in the context of this Thesis, particularly for the linear and nonlinear recession parameters. The extension to the melting season is newly developed in this Thesis, incorporating the earlier extension to the snow accumulation season by Schaefli et al, 2013. A key result of all completed parameter estimation tests for pluvial regimes is the very good performance of an inverse approach based on maximum likelihood estimation (MLE). MLE shows outstanding results even for short series of observations and can be retained as the recommended method to be used for the model framework studied in this Thesis. The extension to the ablation season is achieved by the incorporation of the melting contribution as equivalent precipitation and an ensuing increase of the streamflow producing frequency as compared to the one resulting from rainfall input. The amount of equivalent precipitation is calculated based on the snow accumulation from the existing model extension to winter low flows, combined with a process-based definition of seasons rather than calendar dates. A detailed analysis for all seasons for 10 selected case studies shows that the new seasonal approach yields good results for Alpine streamflow distributions, including for glacier-influenced catchments. The improved parameter estimation methods developed in this Thesis establish a new reference approach for regionalization, opening new perspectives for flow duration curve estimation in ungauged catchments. Other promising results are the consistency of estimated model parameters with underlying physical processes and namely the observed correlation between model parameters and mean catchment elevation. This will allow the study of land use and climate changes in future model applications.

Cilj ovog diplomskog rada je bio analizirati krivulje trajanja na osnovi podataka o vodostajima izmjerenih na jednoj hidrološkoj stanici, te razinama podzemne vode na dva piezometra s lijeve i desne obale rijeke Save u razdoblju od 1993. do 2015. godine, u svrhu utvrđivanja najpovoljnije hidrološke godine. Predmet istraživanja je samoborsko-zaprešićki otvoreni vodonosnik koji je građen od aluvijalnih kvartarnih naslaga međuzrnske poroznosti. Na području ovog vodonosnika zabilježen je višegodišnji kontinuirani negativan trend razina podzemne vode., The main goal of this thesis was to analyse flow duration curves, based on water level data measured on one hydrological station, and two monitoring wells on the left and right Sava river bank, between 1993 and 2015 for the purpose to determine the most suitable hydrological year. The subject of research of this thesis is the Samobor-Zaprešić unconfined aquifer, which is made of alluvial quaternary sediments. Aquifer's area is characterized by continuous multiannual negative trend of ground water levels.

As a major component of the hydrologic cycle, rainfall runoff plays a key role in water resources management and sustainable development. Conceptual models of the rainfall-runoff process are governed by parameters that can rarely be directly determined for use in distributed models, but should be either inferred through good judgment or calibrated against the historical record. Artificial neural network (ANN) models require comparatively fewer such parameters, but their accuracy needs to be checked. This paper compares a Hydrologic Engineering Centre-Hydrologic Modeling System (HEC-HMS) conceptual model and an ANN model based on the conjugate gradient method for streamflow prediction. Daily precipitation, temperature, and streamflow data of the Upper Indus River for a period of 20 years (1985&ndash, 2004) are used as input for calibrating in the case of the HEC-HMS, and for training in case of the ANN. Ten years of data (2005&ndash, 2014) are used to validate the HEC-HMS model and test the ANN. The performance of the models is assessed using different statistical indicators such as the Nash&ndash, Sutcliffe efficiency (NSE), root mean square error (RMSE), mean bias error (MBE), and the coefficient of determination (R2). The results show good predictions for streamflow in the case of both HEC-HMS and ANN models. A parametric study is conducted using Monte Carlo analysis and finds that the most important parameters for HEC-HMS models are the storage coefficient and the time of concentration, while for ANN models, input combinations are the most important. This study investigates the sensitivity of these parameters, which can be used to determine preliminary estimation ranges of their values for future modeling. Finally, evaluating the impact of the simulated streamflow&rsquo, s accuracy on the flow duration curve shows that the curve is significantly affected by any streamflow simulation inaccuracy.

Climate change coupled with increasing urbanization has made extensive green roofs, both for retrofitting and new developments, an attractive way to bring nature back to cities, while managing stormwater. This study has investigated extensive green roof retention and detention performance based on 3–8 years of field data from four Norwegian locations representing typical cold and wet Nordic climates, also comparing several different commercial configurations. Accumulated retention was found to be 11–30% annually and 22–46% in May through October. The performance was found to be strongly dependent in evapotranspiration and less dependent on material storage capacities. Estimates for available storage capacities for precipitation events larger than 5 mm are given and can be useful for design purposes. Median observed peak attenuation compared to the precipitation ranged from 65–90% depending on locations and configurations. The event-based approach for evaluating detention was found to be challenging due to the nature of the precipitation in the studied locations. An alternative approach using flow duration curves based on the observed time series was tested and found to give valuable information on runoff patterns from green roofs and to be useful for evaluating green roof performance in relation to local requirements. © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

[EN] Ecohydrological modeling studies in developing countries, such as sub-Saharan Africa, often face the problem of extensive parametrical requirements and limited available data. Satellite remote sensing data may be able to fill this gap, but require novel methodologies to exploit their spatiotemporal information that could potentially be incorporated into model calibration and validation frameworks. The present study tackles this problem by suggesting an automatic calibration procedure, based on the empirical orthogonal function, for distributed ecohydrological daily models. The procedure is tested with the support of remote sensing data in a data-scarce environment-the upper Ewaso Ngiro river basin in Kenya. In the present application, the TETIS-VEG model is calibrated using only NDVI (Normalized Difference Vegetation Index) data derived from MODIS. The results demonstrate that (1) satellite data of vegetation dynamics can be used to calibrate and validate ecohydrological models in water-controlled and datascarce regions, (2) the model calibrated using only satellite data is able to reproduce both the spatio-temporal vegetation dynamics and the observed discharge at the outlet and (3) the proposed automatic calibration methodology works satisfactorily and it allows for a straightforward incorporation of spatio-temporal data into the calibration and validation framework of a model., The research leading to these results has received funding from the Spanish Ministry of Economy and Competitiveness and FEDER funds, through the research projects ECOTETIS (CGL2011-28776-C02-014) and TETISMED (CGL2014-58127-C3-3-R). The collaboration between Universitat Politecnica de Valencia, Universita degli studi della Basilicata and Princeton University was funded by the Spanish Ministry of Economy and Competitiveness through the EEBB-I-15-10262 fellowship.

In this study we propose a novel method for the estimation of ecological indices describing the habitat suitability of brown trout (Salmo trutta). Traditional hydrological tools are coupled with an innovative regional geostatistical technique, aiming at the prediction of the brown trout habitat suitability index where partial or totally ungauged conditions occur. Several methods for the assessment of ecological indices are already proposed in the scientific literature, but the possibility of exploiting a geostatistical prediction model, such as Topological Kriging, has never been investigated before. In order to develop a regional habitat suitability model we use the habitat suitability curve, obtained from measured data of brown trout adult individuals collected in several river basins across the USA. The Top-kriging prediction model is then employed to assess the spatial correlation between upstream and downstream habitat suitability indices. The study area is the Metauro River basin, located in the central part of Italy (Marche region), for which both water depth and streamflow data were collected. The present analysis focuses on discharge values corresponding to the 0.1-, 0.5-, 0.9-empirical quantiles derived from flow-duration curves available for seven gauging stations located within the study area, for which three different suitability indices (i.e. ψ10, ψ50 and ψ90) are evaluated. The results of this preliminary analysis are encouraging showing Nash-Sutcliffe efficiencies equal to 0.52, 0.65, and 0.69, respectively.

Key Points Analytic model for the probability distribution of snow dominated streamflow Stochastic framework to link precipitation (rain snow) and streamflow dynamics 14 case studies confirm progress in statistical characterization of streamflow We propose a novel analytical description of the streamflow probability distribution functions (pdfs) in Alpine catchments characterized by pronounced snow dominated winter low flows. Knowledge about such hydrological regimes is crucial for water resources management in mountain environments and the related wide range of socio economic environmental and ecological services. We use a stochastic framework generalizing that employed by Botter et al. (2007b) to link precipitation (rain and snow) and streamflow dynamics. The effect of snow dynamics on the flow regime is specifically included by incorporating the temporary disconnection of high elevation areas that experience freezing conditions over the entire winter season and the delay produced on streamflow formation by the temporary accumulation (and later melting) of snow at lower elevations. The novel analytical model employs four parameters that can be directly estimated from observed discharge precipitation and air temperatures and one calibration parameter (the elevation threshold z delimiting catchment areas with a permanent seasonal snow cover that is nonresponsive during winter owing to snow accumulation without melt). We test the developed model for 14 catchments with contrasting hydroclimatic conditions located in the Swiss and the Italian Alps. Overall the proposed analytic model reproduces the observed streamflow pdfs remarkably well. Exceptions exist though and the possible origin of deviations between observed and modeled pdfs are discussed. We suggest that our approach marks a progress toward the general statistical characterization of catchment streamflow variability. ©2013. American Geophysical Union. All Rights Reserved.

Cilj ovog rada bio je odrediti zone samoborsko-zaprešićkog vodonosnika u kojima rijeka Sava drenira ili prihranjuje vodonosnik. Analizirani su vodostaji rijeke Save i razine podzemne vode na temelju krivulja trajanja. Određene su hiporheične zone samoborsko-zaprešićkog vodonosnika pomoću karti ekvipotencijala za niske i srednje vode. Izdvojeno je sedam piezometara u području oko rijeke Save i četiri hidrološke postaje pomoću kojih su izrađena četiri profila na kojima su izvršene analize. Izdvojeni piezometri i hidrološke postaje su statistički obrađeni za razdoblje od 2003. do 2012. godine. U radu su prikazane krivulje trajanja vodostaja i razina podzemne vode, a također su izrađene i tablice za rezultate analize pojedinih godina unutar analiziranog razdoblja., The goal of this thesis was to determine zones of Samobor-Zaprešić aquifer in which Sava river discharges or recharges it. Water lavels of Sava river and groundwater levels were analyzed based on flow duration curves. Hyporheic zones Samobor-Zaprešić aquifer were determined using the head contour maps for low and medium water levels. There were selected 7 piezometers and 4 hydrological stations which were used to create 4 cross-sections that were analyzed. Chosen piezometers and hydrological stations were statistically processed for period 2003 until 2012. Flow duration curves and groundwater levels were shown and also tables were maid to show analysis results for certain years within analyzed period.

The flow duration curve (FDC) is a fundamental signature of the hydrological cycle to support water management strategies. Despite many studies on this topic, its estimation in ungauged basins is still a relevant issue as the FDC is controlled by different types of processes at different time-space scales, thus resulting quite sensitive to the specific case study. In this work, a regional spatially-smooth procedure to evaluate the annual FDC in ungauged basins is proposed, based on the estimation of the L-moments (mean, L-CV and L-skewness) through regression models valid for the whole case study area. In this approach, homogeneous regions are no longer required and the L-moments are allowed to continuously vary along the river network, thus providing a final FDC smoothly evolving for different locations on the river. Regressions are based on a set of topographic, climatic, land use and vegetation descriptors at the basin scale. Moreover, the model ensures that the mean annual runoff is preserved at the river confluences, i.e. the sum of annual flows of the upstream reaches is equal to the predicted annual downstream flow. The proposed model is adapted to incorporate different "sub-models" to account for local information within the regional framework, where man-induced alterations are known, as common in non-pristine catchments. In particular, we propose a module to consider the impact of existing/designed water withdrawals on the L-moments of the FDC. The procedure has been applied to a dataset of daily observation of about 120 gauged basins on the upper Po river basin in North-Western Italy.

U ovom radu analizirani su vodostaji rijeke Save i razine podzemne vode primjenom krivulja trajanja. Cilj rada bio je odrediti zone zagrebačkoga vodonosnika u kojima rijeka Sava pretežito prihranjuje ili drenira podzemne vode. Pomoću karti ekvipotencijala za niske i srednje vode određene su hiporheične zone zagrebačkoga vodonosnika. Odabrano je 45 piezometara u okolici rijeke Save te su, uz pomoć 22 hidrološke postaje, napravljena 22 profila na kojima su izvršene analize. Statistički su obrađeni odabrani piezometri i hidrološke postaje za razdoblje od 2003. do 2012. godine. Izrađene su krivulje trajanja vodostaja i razina podzemne vode koje su prikazani u radu, zajedno s tablicama za dobivene rezultate po pojedinim godinama analiziranog razdoblja., In this thesis water levels of Sava River and groundwater levels were analyzed, using the flow duration curves. The main goal was the identification of the predominant recharge or discharge zones of the Zagreb aquifer. Hyporheic zones of the Zagreb aquifer were determined using the head contour maps for low and medium water levels. In the surrounding area of Sava River, 45 piezometers were chosen, and with the help of 22 hydrological stations, 22 cross-sections were made on which the analysis was performed. All of the data from the piezometers and hydrological stations, from the year 2003 until 2012, were statistically analyzed. Flow duration curves were made and shown in this thesis, along with the tables of obtained results from the certain years.

There is growing evidence that changes in the current hydrological behaviour of urbanizing catchments are a major source of impacts on the downstream water bodies. However, current flow-rates are rarely considered in studies on urban stormwater management, usually focused on extreme flow-rates. We argue that taking into account receiving water-bodies is possible with relatively small modifications in current practices of urban stormwater modelling, through the use of Flow-Duration Curves (FDCs). In this communication we discuss advantages and requirements of the use of FDCs. Then, we present an example of application comparing source control regulations over an urbanized catchment (178 ha) in Nantes, France., Il est de plus en plus reconnu que le changement du comportement hydrologique courant des bassins versants suite à l'urbanisation est l'une des causes principales de la dégradation des milieux aquatiques récepteurs. Cependant, les débits courants sont rarement pris en compte dans les études concernant la gestion des eaux pluviales urbaines, plus centrées sur les débits extrêmes. Dans cet article, nous suggérons qu'il est possible d'intégrer des considérations sur le milieu récepteur avec des modifications relativement mineures dans les pratiques courantes de modélisation des eaux pluviales urbaines, grâce à l'utilisation des courbes des débits classées (FDC, selon l'acronyme anglais). Nous présentons les avantages de l'utilisation des FDC ainsi que les conditions pour les intégrer dans les études hydrologiques. Enfin, nous présentons un exemple d'application où nous comparons des réglementations de contrôle à la source sur un bassin versant urbanisé (178 ha) à Nantes.

We present in this study an adaptation of Topological kriging (or Top-kriging), which makes the geostatistical procedure capable of predicting flow-duration curves (FDCs) in ungauged catchments. Previous applications of Top-kriging mainly focused on the prediction of point streamflow indices (e.g. flood quantiles, low-flow indices, etc.). In this study Top-kriging is used to predict FDCs in ungauged sites as a weighted average of standardised empirical FDCs through the traditional linear-weighting scheme of kriging methods. Our study focuses on the prediction of period-of-record FDCs for 18 unregulated catchments located in Central Italy, for which daily streamflow series with length from 5 to 40 yr are available, together with information on climate referring to the same time-span of each daily streamflow sequence. Empirical FDCs are standardised by a reference streamflow value (i.e. mean annual flow, or mean annual precipitation times the catchment drainage area) and the overall deviation of the curves from this reference value is then used for expressing the hydrological similarity between catchments and for deriving the geostatistical weights. We performed an extensive leave-one-out cross-validation to quantify the accuracy of the proposed technique, and to compare it to traditional regionalisation models that were recently developed for the same study region. The cross-validation points out that Top-kriging is a reliable approach for predicting FDCs, which can significantly outperform traditional regional models in ungauged basins.

En las últimas décadas, las tierras altas andinas de Ecuador se han caracterizado por los esfuerzos de forestación intensos, con el fin de aumentar la rentabilidad económica de las zonas agrícolas menos viables, reducir la erosión y, más recientemente, para secuestrar carbono atmosférico. La forestación con Pinus especie está muy extendida en las altas praderas altitudinales conocidas como páramos. El impacto de Pinus patula forestación en la producción de agua se estudia y se compara con la práctica más común de pastoreo intensivo y el cultivo de la papa en cuatro microcuencas en la cuenca del río Paute en el sur de Ecuador. Dos cuencas están cubiertas de vegetación de pastizales naturales, uno se convierte en Bosque de pinos, y uno se drena, en parte intensamente rozó, y en parte cultivada con patatas. Los resultados indican que la forestación con P. patula reduce la producción de agua en un 50%, o un promedio de 242 mm año -1 . El rendimiento del agua de la cuenca cultivada es muy similar a la de las cuencas naturales, pero el análisis de las curvas de duración de flujo sugiere una respuesta más rápida y una pérdida de flujo base. Estos efectos pueden tener implicaciones importantes para una gestión sostenible del ecosistema de páramo, dado que el páramo es el principal proveedor de agua para las tierras altas andinas Over the last decades, the Andean highlands of Ecuador have been characterised by intense afforestation efforts, in order to increase the economic return of less viable agricultural areas, reduce erosion and, more recently, to sequestrate atmospheric carbon. Afforestation with Pinus species is widespread in the high altitudinal grasslands known as pa´ramos. The impact of Pinus patula afforestation on the water yield is studied and compared to the more common practice of intensive grazing and potato cultivation in four microcatchments in the Paute river basin in south Ecuador. Two catchments are covered with natural grassland vegetation, one is converted to pine forest, and one is drained, partly intensively grazed, and partly cultivated with potatoes. The results indicate that afforestation with P. patula reduces the water yield by about 50%, or an average of 242 mm year1 . The water yield of the cultivated catchment is very similar to that of the natural catchments, but analysis of the flow duration curves suggests a faster response and a loss of base flow. These effects may have important implications for a sustainable management of the páramo ecosystem, given that the pa´ramo is the major water supplier for the Andean highlands. volumen 251; números 1-2