LEE- Hidrolik ve Su Kaynakları Mühendisliği-Doktora

Bu koleksiyon için kalıcı URI

Gözat

Son Başvurular

Şimdi gösteriliyor 1 - 5 / 14
  • Öge
    Investigation of managed aquifer recharge site suitability through multi-tiered decision making approach
    (Graduate School, 2023-09-20) Mouhoumed, Rachid Mohamed ; Özger, Mehmet ; 501202508 ; Hydraulics and Water Resources Engineering
    Globally, groundwater resources encounter notable challenges encompassing issues of chemical contamination, depletion, anthropogenic activities, and seawater intrusion. These challenges are further exacerbated by the prevailing arid climatic conditions and rapid population growth, resulting in restricted recharge and substantial overdraft, respectively. Consequently, the implementation of sustainable measures becomes imperative to facilitate the efficacious and enduring stewardship of these invaluable resources. While diverse management strategies have been proposed and adopted worldwide over the years to contend with these threats, ranging from optimizing pumping rates to enhancing water use efficiency, managed aquifer recharge (MAR) stands out today as one of the most promising technological approaches for addressing the degradation of subsurface resources. MAR entails the injection of reclaimed water (such as stormwater and treated wastewater) into the aquifer via various recharge structures, either for subsequent retrieval during dry period or for environmental enhancement purposes. Besides their acknowledged efficacy in replenishing stressed aquifers, MAR technologies are highly susceptible to instances of failure or suboptimal performance if not meticulously executed within appropriate sites. The process of identifying suitable locations for the construction of recharge facilities is notably intricate, owing to the multitude of decision parameters at play. This challenge is further compounded in countries where MAR remains a novice subject, thereby amplifying the complexity of the task. The exploration of MAR potential through the utilization of integrated geographic information system and multi-criteria decision analysis (GIS-MCDA) techniques is acknowledged within the research community as a valuable and insightful approach. Nonetheless, the MCDA-based decision frameworks proposed in the pertinent literature often lack robust mathematical underpinnings. Furthermore, while the mapping of MAR site suitability is commonly conducted at the watershed level, its implementation at the national and urban scales tends to be overlooked. Hence, besides providing an in-depth literature survey about the state of the art in GIS-MCDA based MAR sites suitability mapping, the studies encompassed within this thesis introduce novel and holistic contributions to the scholarly discourse, spanning both conceptual and methodological dimensions. Within the scope of this thesis, robust and reliable multi-tiered decision making frameworks designed to evaluate the potential of MAR across diverse geographical scales, encompassing national, watershed, and city extend were proposed. Moreover, we introduced a coupled groundwater vulnerability and MAR potential mapping model for the sack of identifying promising regions with minimized vulnerability to contamination for MAR implementation. In the first study conducted in this thesis, a robust approach that combines fuzzy analytical hierarchy process (AHP) and technique for order of preference by similarity to ideal solution (TOPSIS) to delineate suitable sites for MAR structures at a countrywide scale was proposed. The proposed model is applied to Djibouti, a hot, dry, and water-stressed country. A set of nine decision criteria were identified and a pairwise comparison survey was conducted to determine their relative importance. Additionally, the TOPSIS method was employed to integrate the decision layers and prioritize the study area. The results highlight the significance of rainfall, slope, and NDVI as the most influential decision parameters, while drainage density has the least impact. The suitability analysis reveals that 10.63%, 23.20%, and 31.06% of the country have very high, high, and moderate potential for MAR activities, respectively. Furthermore, an evaluation of viable MAR technologies within the nation is conducted based on the specific conditions prevailing in Djibouti. At the watershed level, the second study within this thesis focuses on a significant MAR technology extensively employed in arid and semi-arid regions: rainwater harvesting (RWH). RWH offers a promising strategy to address the pervasive challenge of water scarcity in such regions. It involves capturing stormwater for domestic and agricultural use while contributing to aquifer replenishment. In this research, a hybrid approach is proposed, integrating fuzzy AHP and VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) algorithms. This approach is implemented in the water-stressed southeastern basin of Djibouti. This study represents the pioneering endeavor to comprehensively assess RWH potential in Djibouti. Despite existing RWH practices in the country, their implementation often lacks robust scientific foundations, resulting in reduced effectiveness and operational vulnerabilities. A hierarchical structure with 12 decision parameters is formulated, organized into 3 dimensions: physical, environmental, and socio-economic. These dimensions are further divided into 4 specific criteria, establishing a comprehensive framework for addressing the complex issue. Notably, this research extends the incorporation of socio-economic parameters beyond constraint mapping, encompassing suitability analysis as well. Additionally, the application of the VIKOR algorithm for RWH mapping is unprecedented in the literature, marking a pioneering contribution. Findings highlight the significance of the environmental (47.67%) and physical (37.98%) dimensions, with the socio-economic cluster (14.35%) exhibiting lower importance in the fuzzy AHP analysis. Also, the suitability map reveals a substantial area, approximately 872.5 km2, with moderate to very high suitability for various RWH structures like check dams, percolation tanks, and terracing. Regarding the third study, the potential of drywells in an urban environment was investigated using multi-tiered decision approach. In fact, despite existing several MAR technologies, land availability for installation and limited municipal budget restrict their usage, especially in urbanized areas. Consequently, drywells emerge as a highly regarded solution for replenishing stressed shallow urban aquifers, primarily owing their reputation to their minimal land requirement and cost-effectiveness aligned with municipal budgets. Nevertheless, the widespread implementation of drywells is hampered by the absence of comprehensive guidelines and frameworks governing their sitting. In this third research endeavor, a coupled fuzzy AHP and TOPSIS model is proposed to identify favorable zones for drywell construction in the urban city of Kayseri, Turkey—an area prone to declining water tables. It is noteworthy that this research represents the initial attempt in investigating the site suitability of drywells through an integrated GIS-MCDA technique. Based on an in-depth literature survey and technical reports relevant decision criteria were selected and their relative weights were determined through the fuzzy AHP. The results indicated that hydraulic conductivity, depth to groundwater, soil texture, and land use/land cover were the most determining criteria with 33.9%, 17.8%, 11.2%, and 10.1% of weights, respectively. The validation of these criterion weights was conducted by comparing them with those from previous MAR suitability mapping efforts in relevant literature. Additionally, a sensitivity analysis was performed to underscore the robustness and stability of the findings under various degrees of fuzziness. Finally, the study area was divided into 54 sub-regions based on the road-network of the city and the TOPSIS was applied to prioritize the sub-regions to help identify promising areas for the vadose zone wells construction. Concerning the fourth study in this thesis, a combined groundwater vulnerability and MAR sites suitability mapping model was introduced in the pertinent literature. Notably, while drywells stand out as a superior MAR technology in urban environments, the task of identifying appropriate locations with minimal susceptibility to contamination for drywell projects presents an intricate challenge. Hence, the present research proposes a framework encapsulating the combined assessment of groundwater vulnerability and MAR sites suitability analysis to pinpoint the most featured areas for installing drywells in Kayseri, Turkey. To extrapolate the vulnerable zones, not only the original DRASTIC but also its MCDA based modified variants were evaluated with regard to different hydrochemical parameters using the area under the receiver operating characteristic (ROC) curve (AUC). Besides, the fuzzy AHP rationale was adopted to signify the importance level of criteria and the robustness of the framework was highlighted with sensitivity analysis. In addition, the decision layers and the attained vulnerability layer were combined using the weighted overlay (WOA). The findings indicate that the DRASTIC-SWARA correlates well with the arsenic (AUC=0.856) and chloride (AUC=0.648) and was adopted as the vulnerability model. Groundwater quality parameters such as chloride and sodium adsorption ratio, as well as the vadose zone thickness, were found to be the most significant decision parameters with importance levels of 16.75%, 14.51%, and 15.73%, respectively. Overall, 28.24% of the study area was unsuitable for recharge activities with high to very high vulnerability, while the remaining part was further prioritized into low to high suitability classes for MAR application. The proposed framework offers valuable tool to decision makers for the delineation of favorable MAR sites with minimized susceptibility to contamination. The decision frameworks proposed within this thesis empower policy-makers and stakeholders to efficiently discern and prioritize regions exhibiting promising MAR potential across various geographical scales. Particularly, the outcomes from the initial two investigations in this thesis hold primary relevance for Djibouti's water resources authorities, aimed at bolstering sustainable water resource management through MAR and RWH strategies in the country. Regarding the third study, it is believed that the proposed GIS-based hybrid MCDA framework in delineating sites favorable for drywells construction can be adopted by municipalities lacking guidelines and standards for sitting drywells. Furthermore, it is anticipated that the integrated model presented in the final study of this thesis can facilitate the sustainable management of aquifers and contribute to the mitigation of water scarcity challenges in various global regions, all while minimizing the risk of MAR project failure due to the installation of recharge facilities in areas susceptible to groundwater contamination.
  • Öge
    Data-based analysis of drought propagation
    (Graduate School, 2023-08-07) Yıldırım, Işılsu ; Aksoy, Hafzullah ; 501162503 ; Hydraulics and Water Resources Engineering
    In order to better understand the drought, it is crucial to investigate its different types and how it evolves, which is known as drought propagation. This study provides an in-depth investigation of the mechanisms behind drought propagation, focusing on four key issues: (i) intermittency as an indicator of hydrological drought, (ii) identification of drought events, (iii) drought evolution, and (iv) propagation from meteorological drought to hydrological drought. The study utilizes a comprehensive data set from three river basins in western Turkey, namely Kucuk Menderes, Gediz, and Ergene, as robust case studies. After introduction in Chapter 1, the study begins with a literature review on drought in Chapter 2, which leads to the formulation of research questions. The study area and data are presented in Chapter 3. Chapter 4 presents the analysis of intermittency as an indicator of hydrological drought. The dataset from the three river basins is used to explore the link between intermittency in the streamflow and groundwater. It is seen that there has been an increase in water demand in the river basins, and the only solution for balancing the water demand and supply is the groundwater, which is already being overused. The overuse of groundwater causes the water table to descend, streamflow to decrease, and the intermittency ratio of streamflow to increase, resulting in a vicious cycle that leads to a no-water future if no action is taken. This part of the study introduces the concept of intermittency cycle and suggests the intermittency as an indicator of drought in streamflow and groundwater. Chapter 5 introduces a new method to identify drought events by eliminating short and weak wet periods between subsequent droughts. The method was applied in Gediz River Basin to examine the average duration and intensity of drought events across the basin. It was found that drought duration and intensity do not vary greatly over the basin, but the minor variation could be important depending on the practical problem being addressed. The focus of Chapter 6 is on the drought evolution referring to the transition between different drought classes. A method was proposed to calculate drought class probability, expected residence time, and expected initial transition time using precipitation data. Additionally, two new concepts are introduced to improve the proposed method. Results show that the probability of drought occurrence decreases as the drought severity increases, and the expected residence time in each drought class decreases as the drought severity increases from the near normal class to the severe drought class. Results also highlight the importance of considering the expected first transition time, with the longest time observed in the extreme drought class indicating the persistency of this particular class of drought. These findings can be useful in developing preventive measures against drought. Chapter 7 introduces the concept of Formative Drought Rate (FDR) as a potential prediction tool for drought propagation, and tests it on precipitation and streamflow data from three river basins in Turkey. Results show that the FDR is capable of providing prior information for the prediction of drought propagation, which is valuable for drought mitigation. The comparison with Drought Propagation Rate (DPR) from literature supports the use of FDR as a start-up tool, needing further testing in different basins to increase its reliability. Overall, this study introduces new tools and methods to understand drought propagation mechanism, with each chapter presenting the details of the tools and the methods through various case studies. The insights gained from this study can be applied in drought mitigation efforts in any region facing similar challenges. Further research and case studies can improve the tools and the methods and expand our knowledge on drought propagation. The insights gained from this study can suggest new avenues for the future research. The FDR is an open issue for further development. It could be applied to different data sets that represent different types of droughts, such as the groundwater level, to gain a better understanding of the propagation between droughts in precipitation, streamflow, and groundwater.
  • Öge
    Investigation of new type wave energy converter systems
    (Graduate School, 2024-02-09) Mandev, Murat Barış ; Altunkaynak, Abdüsselam ; 501202503 ; Hydraulics and Water Resources Engineering
    In consideration of the evolving global economy and increasing population, energy is increasingly occupying a more important place in our lives. As commonly understood, energy sources can be categorized into two groups: non-renewable and renewable. A renewable energy source is defined as an energy source that can exist the next day within the natural order of the Earth. The most significant features of renewable energy sources include reducing carbon dioxide emissions to help protect the environment, decreasing dependence on foreign energy sources due to being local resources, contributing to increased employment, and receiving widespread and strong support from the public. In other words, renewable energy sources possess characteristics of accessibility, availability, and acceptability. Among renewable energy sources, wave energy, despite being approximately 10 times more intense than solar energy per square meter and 5 to 10 times more intense than wind energy, has a very low utilization rate compared to others. Efforts to harness wave energy are rapidly increasing worldwide. It is a predictable fact that our country, surrounded by seas on three sides, has significant potential for wave energy, and the use of this energy type will reduce external dependence. Wave energy converters are used to convert wave energy in the seas into electrical energy. Among these converters, oscillating water column (OWC) type converters are the most efficient. The oscillating water column is a system consisting of two phases: water and air flow. Moving according to the periodic structure of the wave, the water converter compresses the air inside, allowing it to exit at a certain speed from the outlet. Therefore, the parameters affecting this system are the periodic movement of the wave, the dimensions of the converter, and the dimensions of the outlet. Until now, studies have been conducted on OWC energy converters, and prototypes have been developed by testing various models. However, due to the complexity of the energy conversion mechanism, commercial production has not achieved the desired efficiency from these studies. This thesis is composed of three separate articles, each written by designing new oscillating water column-type wave energy converters, calculating their efficiencies, and compiling the results into articles. In the first article, a new tank design is proposed for an oscillating water column (OWC) with an inclined wall to improve performance. Physical experiments were conducted for different orifice damping levels and sea conditions to calculate hydrodynamic performance. The results were compared with the results of a classic OWC design. According to the comparison, it was observed that the new chamber design had a significant impact on OWC efficiency. The proposed chamber design geometry increased OWC performance by up to 31% for wave parameters where the OWC operates effectively. Additionally, the results show that the optimal orifice damping level for the highest efficiency increase is dependent on the chamber design. The aerodynamic geometry of the chamber increased OWC efficiency by 54% maximum and 44% average even when there is internal slosihng in the tank. The second article focuses on optimizing the diameter of the cylindrical front wall entry of the OWC. Specifically, 240 physical experiments were conducted for five different diameter values, various orifice dampings, dimensionless wave frequencies (Kh), and wave heights. It was found that the cylindrical front wall entry geometry consistently improved OWC efficiency under all conditions. Maximum and average efficiency improvements were calculated as 45% and 25%, respectively. The simplicity of the modification at the front entrance makes this improvement even more interesting. A negative correlation was observed between the size of the diameter and Kh. Optimal sizes for the diameter were identified as 12 cm, 7 cm, and 5 cm for low, medium, and large Kh values, respectively. The diameter maximizing efficiency in a specific frequency band was determined based on wave height and orifice ratio. To validate the effectiveness of cylindrical geometry, experiments in free decay were conducted, demonstrating that modifying the front entrance mitigated or reduced flow separation caused by the sharp lower cut. Consequently, the utilization of a cylindrical front wall underlip geometry proved beneficial in reducing shear stresses on both sides of the front wall and enhancing the structural integrity of the OWC model. In the third article, hydrodynamic features evaluating the wave energy collection potential of a double-chambered OWC structure were examined through a series of experiments. The study used efficiency as a measure to quantitatively assess the performance of the OWC system by changing front wall designs, power orifice dampings, and wave conditions. The findings show that the double-chambered configuration consistently exhibited improved performance for the studied orifice ratios, opening heights, and incoming wave frequencies combinations. Increasing the opening height of the second chamber improved the performance of the OWC, as expected. Interestingly, the effect of applied orifice damping on efficiency was found to be relatively insensitive. The most significant improvements in efficiency values were observed for larger wave frequency values. For example, for dimensionless wave frequency (Kh) values of 1.43 and 1.68, efficiency increased from 0.47 to 0.72 and from 0.26 to 0.52, respectively, with the orifice ratio combination of τ1, 0.015 and τ2, 0.018. While the single-chambered OWC effectively operated in the resonance frequency range of 0.94-1.23, the double-chambered design expanded this frequency range, allowing effective wave energy collection over a wider spectrum of wave conditions. The double-chambered configuration offers significant advantages by increasing the effective frequency bandwidth for efficient energy conversion in wave energy conversion applications. Research findings have shown that this innovative design has the potential to significantly increase the efficiency and adaptability of wave energy converters. The results indicate that improvements and innovations in wave energy technologies will make it possible to use this energy source more efficiently and reliably. However, overcoming challenges at the application scale and economic barriers will require further work and investment. This thesis seeks to establish a comprehensive framework for both research and industrial applications within the wave energy field, highlighting the considerable potential of wave energy. In summary, the goal of this investigation is to enhance our understanding, make progress in wave energy technology, and play a role in shaping a sustainable energy future.
  • Öge
    Development of drought intensity-duration-frequency curves based on standardized climatic indices using physical variables, deficit in precipitation and deficit in streamflow
    (Graduate School, 2023-11-13) Çavuş, Yonca ; Aksoy, Hafzullah ; Stahl, Kerstin ; 501192503 ; Hydraulics and Water Resources Engineering
    Drought is a natural disaster that causes water scarcity and affects the population seriously in many ways such as economic, social and environmental impacts. These effects have been further aggravated by rising demands for agricultural, municipal and industrial water, etc. due to the growing population coupled with rising life standards and increasing industrialization in the world. Compared to other natural hazards, drought is among the most damaging disasters as it develops slowly over a considerable period of time that may linger for several years even after the drought has terminated. How important the drought is in the sustainability of water resources requires an extra effort to understand and explain. Domestic use, agriculture, industry, energy, tourism and many more sectors are exposed to drought, which has a direct impact on ecology, economy and society. As one of the least understood hydrological phenomena, drought stands as both a technical and social problem. This is a great motivation to explore drought concepts and methodologies in this thesis by extending them from their quantitative technical context to qualitative social context. Case studies were performed in two river basins with different climatic characteristics. One is Seyhan River Basin in the south of Turkey with a Mediterranean climate, and another is the Kocher catchment in the southwestern corner of Germany with a humid subtropical climate. In the literature, the drought is commonly analyzed by the use of available hydroclimatic or hydrologic data with little in-depth consideration of specific major dry periods experienced over a region. Also, it is not a common practice to assess the probability of drought categories with a rolling time series and hence the changing knowledge for operational drought monitoring. A combination of such quantitative analysis with a comprehensive qualitative assessment of drought as a human-water relation aimed to fill this gap by performing a case study in the Seyhan River Basin, Turkey. Therefore, the first part of this thesis focuses on non-stationary rolling time series analysis together with the stationary full-record time series analysis and the individual major dry period analysis. Six major dry periods were identified from the precipitation time series of 19 meteorological stations. Dry periods extended over 1970-1974, 2002-2008, and 2013-2015, known also as droughts of 1974, 2008, and 2014, respectively, should particularly be noted among all as they affected several sectors in the river basin with the long-lasting deficit in water. Major dry periods were analyzed by rolling time series and full time series, and they were also analyzed individually. The results show that significantly higher probabilities were calculated for extreme droughts with the use of individual major dry periods. An important outcome of the study is that drought is underestimated in practice with the sole use of the whole data record. Also, a major dry period could be important in terms of its duration while another in terms of its severity or intensity. Each major dry period has its own impact on human-water relations that can be influential on drought mitigation, management and governance. The second part of the thesis investigates the statistical properties of drought characteristics for a better understanding of drought to mitigate its negative impacts and improve drought management strategies. Differently from the common approach based on the run theory, the hypothesis is that drought is different from the dry period and dry periods identify droughts of different durations. Up to now, no attention has been paid in this sense to the statistical properties of dry periods versus those of more severe and impactful droughts as separate phenomena. The study shows how different the statistical properties of dry periods and droughts are by quantifying them with the Standardized Precipitation Index (SPI) together with the total probability theorem-coupled frequency analysis. The study tests four concepts in this context: (1) Dry period, (2) Critical drought for a dry period, (3) Critical drought for a year. The results uncover the high number of droughts, which are not addressed in the run theory, and reveal more intense droughts that are masked within the dry periods. Specifically, the drought impact is more often related to drought intensity than severity and duration. In addition, the dry period is less intense than other concepts. Among the droughts newly proposed, critical droughts are the most intense concepts. This demonstrates that drought characteristics calculated for the drought concepts are different from the common approach of the dry period. The difference among the concepts is large enough to carry potential implications for local or regional scale drought management planning. In the third study, drought intensity-duration-frequency (IDF) curves were developed by using the critical drought identified in the second study. The drought IDF curves are based on precipitation and streamflow deficits because drought estimates in terms of physically measurable variables are key knowledge for effective water management. However, how these deficits vary with the drought event severity indicated by commonly used standardized indices is often unclear. Drought characteristics assigned the same value in the index are not necessarily the same in different regions, and in different months of the same region. The study investigates drought to remove this disadvantage of the index-based drought IDF curves and develop intensity-duration-frequency (IDF) curves in terms of the associated deficit. In order to study the variation of deficits, the link between precipitation and streamflow was used, and the associated indices, standardized precipitation index (SPI) and standardized streamflow index (SSI). More specifically, the analysis relies on frequency analysis combined with the total probability theorem applied to the critical drought severity. The critical drought has varying durations and it is extracted from dry periods. IDF curves in terms of precipitation and streamflow deficits for the most severe drought of each drought duration in each year are then subject to the comparison of statistical characteristics of droughts for different return periods. Precipitation and streamflow data from two catchments, the Seyhan River (Turkey) and the Kocher River (Germany) provide examples of two climatically and hydrologically different cases. A comparison of the two cases allows to test a similar method in different hydrological conditions. The results show that precipitation and streamflow deficits vary systematically reflecting seasonality and the magnitude of precipitation and streamflow characteristics of the catchments. Deficits change from one month to another at a given station. Higher precipitation deficits were observed in winter months compared to summer months. Additionally, major droughts experienced in both catchments on the IDF curves show that the major droughts have return periods at the order of years at short durations. This coincides with the observation in the catchments and shows the applicability of the IDF curves. The IDF curves can be considered a tool for the use in a range of specific activities of agriculture, ecology, industry, energy, water supply, etc. This is particularly important to end-users and decision-makers to act against the drought quickly and precisely in a more physically understandable manner. Other than quantitative methodologies, drought was also analyzed by a qualitative approach. Using the causal loop diagram, the drought event of 2008 observed in the Seyhan River Basin was taken as an example to focus on the identification of bidirectional feedback between humans and water under drought conditions. This particular drought is short but severe as it coincided with the least amount of precipitation ever recorded in the river basin. It is an important example because it gave an impetus to the governmental water authorities to initiate basin-scale drought management plans. The quantitative and qualitative data collected for this drought were used in the causal loop analysis. The causal loop diagram shows that short-term measures under economic, structural and conservation frameworks can only provide temporary solutions which may aggravate drought impact. A sustainable water availability under drought conditions can only be achieved by long-term reactions such as drought management plans. In summary, the thesis contributes to drought analysis research by proposing new methodologies and drought concepts. The outcomes of the study underline the need for such drought analyses. The analysis of the conceptualization reveals strong differences among the statistical properties of the drought characteristics. Moreover, the thesis emphasizes the region-specific characteristics of drought that need to be considered for drought management strategies.
  • Öge
    Fizik tabanlı tam yayılı hidrolojik modellerin kalibrasyonunda uydu tabanlı verilerin kullanılması
    (Lisansüstü Eğitim Enstitüsü, 2023-01-31) Avcuoğlu, Muhammet Bahattin ; Demirel, Mehmet Cüneyd ; 501072503 ; Hidrolik ve Su Kaynakları Mühendisliği
    Hidrolojik model parametreleri geleneksel yaklaşımda havza çıkışında gözlenen günlük nehir akım verileriyle tahmin edilmeye çalışılır. Modern yaklaşımda ise akım verileri yanında herkese açık uydu tabanlı uzaktan algılama verilerinden de azami istifade edilmeye çalışılır. Uzaktan algılama verilerinin kullanıldığı yöntem ile ulaşılan alansal model çıktıları, sadece akım verisiyle elde edilen noktasal iyileştirme sonuçlarına göre daha tutarlı ve güvenilirdir. Bu nedenle fizik tabanlı sonlu elemanlar yöntemiyle çalışan matematiksel havza modellerinin uydu verileriyle kalibrasyonu dünyada giderek yaygınlaşmaktadır. Bu çalışmamızın amacı uzaktan algılama yöntemleriyle elde edilmiş buharlaşma ve terleme verilerinin hidrolojik model kalibrasyonuna etkilerini araştırmaktır. Bunun için veri kalitesi yüksek Fransa'nın Vienne havzasında fizik tabanlı tam yayılı mHM modeli kurulmuş ve 11 senaryolu kalibrasyon deneyleri yapılmıştır. 2002-2014 kalibrasyon dönemindeki modelin akım benzeşim performansı modelin günlük akım çıktıları ile gözlenen akım değerleri arasında hesaplanan KGE, modelin alana yayılı fiziksel performansı ise mHM'in uzun dönem (2002-2014) aylık buharlaşma ve terleme (AET) raster çıktı haritaları ile referans MODIS-AET raster haritaları arasında üçer aylık üç dönemde (1. dönem: Mart, Nisan, Mayıs, 2. dönem: Haziran, Temmuz, Ağustos 3. dönem: Eylül, Ekim, Kasım için) hesaplanan SPAEF değerleri ile ortaya konmuştur. 1998-2001 arası 4 yıl ön koşturma (spin-up) dönemi olduğundan performans hesaplarına dahil edilmemiştir. Model parametreleri Ostrich yazılımı içerisinde bulunan 750 iterasyonlu paralel pareto-DDS (PARA-PADDS) yöntemi kullanarak kalibre edilmiştir. Sonuçlara göre, sadece havza çıkışında konumlandırılan bir tek akım gözlem istasyonundan elde edilen akım verilerinin kullanıldığı kalibrasyonda (senaryo 1) modelin akım performansı beklendiği gibi çok yüksek (KGE 0.91, maksimum değeri 1); modelin AET performansı ise üç dönemde de çok düşüktür (SPAEF -0.16, -0.21, -0.26). Havza çıkışındaki AGİ ve nehrin farklı alt kollarında konuşlu 3 AGİ'den alınan akım verileriyle 4 AGİ'li kalibrasyonda (senaryo 2) ortalama KGE 0.91'den 0.37'ye düşerken ve üç dönemin SPAEF değerleri -0.72, 0.76, 0.55 olmuştur. Tek AGİ ve uydu verili kalibrasyonda (senaryo 3) akım performansında 0.91'den düşme çok sınırlı olmuş (KGE 0.90), bunun yanında AET performansı üç dönemde de önemli oranda iyileşmiştir (SPAEF 0.64, 0.77, 0.74). Akım ölçümü hiç olmayan sadece uydu verili kalibrasyonda (4. senaryo) su dengesi sağlanamamış (KGE -0.24), üç dönemde SPAEF 0.39, 0.69, 0.67 değerlerini almıştır. Veri eksikliği yaşanan havzalar için iki senaryo (5 ve 6) kurgulanmıştır. Bir yılda ve sadece her ayın ortasında tek ölçüm, toplamda 12 adet akım verisi ve MODIS-AET uydu verisiyle kalibrasyonda (senaryo 5) su dengesi ve AET performansının iyileştiği gözlemlenmiştir (KGE 0.67 ve üç dönemde SPAEF 0.65, 0.82, 0.76). MODIS-AET yanında sadece bir yıllık günlük akım verileri kullanılan 6. senaryoda KGE 0.72 ve üç dönemde SPAEF 0.64, 0.80, 0,79 değerlerini almıştır. Kurgulanan diğer 5 farklı senaryoda karasal gözlemler yerine global akış verilerinden elde edilen zaman serileri kullanılmıştır. Bu diğerlerinden farklı 5 senaryoda bilhassa hiçbir ölçüm verisinin olmadığı havzalarda çok amaçlı çoklu kalibrasyon yaklaşımının karasal gözlemlerden tamamen bağımsız olarak yürütülüp yürütülemeyeceği sorusuna cevap aranmıştır. ERA5_LAND ve GLDAS akış verilerinin kullanıldığı senaryolarda uydu verisi MODIS-AET kullanılmıştır. Bu senaryolar içinde S11`de GLDAS ve MODIS-AET aylık ortalamalar ile yapılan çok amaçlı çoklu kalibrasyonda su dengesi önemli ölçüde sağlanmıştır. Bu senaryo kurgusunda diğerlerinde olduğu gibi karasal gözlemlerin bulunmadığı kabulünden yola çıkarak akış verisi ve AET verisi ücretsiz olarak uydu ve uydu bazlı yeniden analiz ürünü olarak temin edilmiştir. GLDAS global yeniden analiz ürünü yayılı akış verileri uzun yıllar ortalması 12 aylık zaman serilerine dönüştürülerek MODIS`den alınan yayılı AET verileri ile birlikte kalibrasyonda kullanılmıştır. KGE değerinin 0,37`ye çıkmasına rağmen SPAEF değerlerinin sırası ile 0,63; 0,78 ve 0,75 değerlerini alması diğerleri ile kıyaslandığında su dengesini önemli ölçüde sağlamıştır. S7 senaryosunda 2002-2014 yılları arası ERA5_LAND akış verisinin zaman serileri kullanılırken MODIS AET verileri patern yönünden hedeflenmiştir. Bu kurguda KGE değerleri sıfıra yakın çok küçük değerler alırken SPAEF okumaları HTA ve EEK dönemlerinde yüksek okumalar vermiştir. Fakat su dengesi sağlanamamıştır. S8 kurgusunda ERA5_LAND için 2002-2014 arası uzun dönem aylık veriler kalibrasyonda kullanılmıştır. MODIS AET veriside çok amaçlı çoklu kalibrasyonun diğer amaç fonksiyonuna konu edilen alansal girdisi olmuştur. Bu kurguda SPAEF değerlerinin yüksek değerler alması (0,64; 0,78; 0,73) yanında KGE okumaları sınırlı bir iyileşme göstermiştir (0,18). Her ne kadar havzanın fiziki temsili iyileşmiş olsada su dengesi sınırlı kalmıştır. 9 numaralı senaryoda akış verisi uzun yılların ortalaması alınarak aylık toplamlar şeklinde akış serilerine sokulurken kalibrasyon için bir diğer girdi yine MODIS AET olmuştur. Bu kurguda SPAEF değerleri önemli ölçüde yükselme gösterirken (0,63; 0,77; 0,80) KGE değeri eksi değerler alarak (-0,18) su dengesinden uzaklaşılmıştır. S10 için yapılan kurguda hatanın amaçlandığı akış serileri ve patern yönünden amaçlanan AET verileri ERA5_LAND ürünü olarak temin edilmiş ve kalibrasyonda başka bir veri kullanılmamıştır. ERA5_LAND akış ve AET verileri uzun yıllar aylık ortalamalar şeklinde kalibrasyonda kullanılmıştır. Bu kalibrasyon neticesinde elde edilen debi ve AET simülasyonlarına ait benzeşim başarısı KGE için -0,23 değerini alırken SPAEF değerleri sırası ile 0,02; 0,29 ve 0,37 değerlerini almıştır. Su dengesinin en fazla bozulduğu ve performansı en düşük olan senaryo kurgusu burada ortaya çıkmıştır. Global ürünlerle yapılan kalibrasyonda en iyi performansı S11 senaryosu sağlarken en kötüsünü S10 sağlamıştır. Sonuçlarımız akım ölçümleri eksik ve yetersiz havzalar için ümit vericidir. Bu çalışma, fizik tabanlı modellerin uydu verileri ve uygun amaç fonksiyonları ile kalibre edildiklerinde havzanın fiziğiyle uyumlu, su dengesini de bozmayan optimum parametre setine ulaşılabildiğini göstermiştir. Bir diğer önemli çıktı ise karasal gözlemlerin hiç olmadığı bir havzada dahi ücretsiz uydu verileri ve global ürünler kullanılarak kalibrasyon başarısı sağlanabilmektedir.