Gökçen Uysal

Eskişehir Technical University · Department of Civil Engineering

This study aims to analyze future snowmelt runoff and snow extent for the Upper Euphrates Basin (41 109 km2) which is the most upstream basin of the water tower Mesopotamia and located in the Eastern mountainous part of Türkiye. The future characterization of snowmelt runoff and snow water equivalent is investigated taking the regional climate mode...

Mountainous basins are frequently called “natural water towers” because they supply essential water to downstream regions for irrigation, industrial–municipal use, and hydropower generation. The possible implications of climate change on water supplies have gained prominence in recent years, particularly in snow-dominated mountainous basins. The Eu...

The operation of upstream reservoirs in mountainous regions fed by snowmelt is highly challenging. This is partly due to scarce information given harsh topographic conditions and a lack of monitoring stations. In this sense, snow observations from remote sensing provide additional and relevant information about the current conditions of the basin....

Investments in renewable energy systems have been increasing in recent years in order to reduce climate-dependent fossil fuels and to supply the increased energy demand. One of the main difficulties with renewable resources is that they depend on meteorological conditions and produce intermittent energy. Energy storage systems are being developed t...

It is important to determine the flood effects due to dam break on the downstream region for disaster preparedness studies. In this work, the flood risk potential of the residential area located downstream of Batman Dam was investigated. The study consists of two phases which are integrated within the HEC-RAS model. In the first stage, the flood hy...

Satellite technology offers alternative products for hydrological applications; however, products should be validated with benchmark models and/or data sets for operational purposes. This study assesses the performance of the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) Satellite Application Facility on Support...

Climate change will alter the inflows into the dam in the future; thus, the balance between water supply and water availability will directly impact the water levels and indirectly affects dam safety. Therefore, estimating the future inflows and reservoir water content can help the operators. In this study, a machine learning Wavelet-MultiLayer Per...

Satellite-based Precipitation (SBP) products are receiving growing attention, and their utilization in hydrological applications is essential for better water resource management. However, their assessment is still lacking for data-sparse mountainous regions. This study reveals the performances of four available PERSIANN family products of low reso...

Open and free data underpin a new way of thinking about what is required to advance scientific discoveries. The fourth paradigm for hydrology, i.e. data-intensive science, can only lead to transformative science and groundbreaking findings if data is freely accessible. Open datasets are available online, are accessible in machine-readable formats (...

Snowmelt modeling is vital issue for proper operational flow forecasting systems but still challenging in upstream mountainous basins due to limited observations and associated uncertainties. Data assimilation is a valuable tool to improve model state estimates to improve hydrological forecast. While assimilation of snow has been increasingly imple...

The frequency of floods and droughts is increasing due to climate change and preparedness becomes vital to deal with these disasters. One important tool is to apply flood simulations and to derive flood maps, but the availability of hydraulic simulations conducted in the river alignment is mainly based on the availability of the geometry of the flo...

Estimating snowmelt runoff in mountainous basins is a challenging task due to limited precipitation measurements. Satellite-based Precipitation Products (SBPs) are readily available, but still suffer from large errors in cold climate regions. This study aims to evaluate and propose post-bias corrections for uncorrected Precipitation Estimation from...

Precipitation is one of the essential key factors in many hydrological studies. With the development of new technologies for meteorological variables, a different source of monitoring tools and methods over extra time and space scales are on the agenda. Satellite precipitation data sets are one of these new products and still need to be validated w...

This study aims to deploy a short term hydrological forecast system in snow dominated mountainous basins. The headwaters of Euphrates and Seyhan Basins, selected as study areas, stand out with their high water potential, snow melt feeding this potential and the presence of large and important water structures in the downstream. For the simulation o...

Evaluation of problems related to water resources development and management require accurate precipitation estimates. Although ground-based stations provide direct physical measurement of precipitation, the accuracy of gauge-based precipitation data in terms of quality and spatial pattern may still be controversial. On the other hand, Gridded Prec...

Streamflow prediction is often a challenging issue for snow dominated basins where proper in-situ snow data might be limited and the snow physics is highly complex. The main aim of this study is to propose an alternative modeling solution by considering both accessibility of the inputs and simplicity of the model structure. We propose Wavelet Neura...

This study was presented at EGU 2020: Sharing Geoscience Online

Modeling streamflows is challenging in snow dominated high altitude regions due to limited observations, harsh topographic conditions and complex snow physics. Different uncertainties arise from multiple sources in modeling and forecasting. The uncertainties of the initial conditions are mainly tackled with data assimilation techniques. On the othe...

Predicting snow cover dynamics and relevant streamflow due to snowmelt is a challenging issue in mountainous basins. Spatio-temporal variations of snow extent can be analyzed using probabilistic snow cover maps derived from satellite images within a relatively long period. In this study, Probabilistic Snow Depletion Curves (P-SDCs) and Proba-bilist...

The short-term, optimal management of storage reservoirs is challenging due to multiple objectives, i.e. hydropower, water supply or flood mitigation, and inherent uncertainties of forecasts for inflow and water demand. Model Predictive Control (MPC) provides an online solution for this management problem by combining a process model, forecasts and...

Optimal control of reservoirs is a challenging task due to conflicting objectives, complex system structure, and uncertainties in the system. Real time control decisions suffer from streamflow forecast uncertainty. This study aims to use Probabilistic Streamflow Forecasts (PSFs) having a lead-time up to 48 h as input for the recurrent reservoir ope...

Reservoir operations require enhanced operating procedures for water systems under stress attributed to growing water demand and consequences of changing hydro-climatic conditions. This study focuses on the management of the Yuvacik Dam Reservoir for water supply and flood mitigation in the Marmara Region of Turkey. We present an improved operating...

Data driven techniques have become well-known application in hydrology in which physical processes are highly nonlinear. They require detailed analyses of different input combinations, selecting the appropriate model structures, assigning the optimization parameters etc. Besides, the model performance are also highly correlated with additional anal...

Operation of water structures especially with conflicting water supply and flood mitigation objectives is under more stress attributed to growing water demand and changing hydro-climatic conditions. Model Predictive Control (MPC) based optimal control solutions has been successfully applied to different water resources applications. In this study,...

Flood risk mitigation during real time flood events comprising snowmelt under hydrological uncertainty is particularly challenging. Giving this due consideration, the aim is to develop a Decision Support System for the real time operation of a reservoir and the channel downstream. This was accomplished with continuous catchment monitoring, runoff f...

This paper investigates the contribution of Moderate Resolution Imaging Spectroradiometer (MODIS) satellite Snow Cover Area (SCA) product and in-situ snow depth measurements to Artificial Neural Network model (ANN) based daily streamflow forecasting in a mountainous river basin. In order to represent non-linear structure of the snowmelt process, Mu...

When designing water structures or managing a watershed it is a challenging task to determine the response of a basin to storm and/or snowmelt. In this study, the Upper Euphrates Basin (10,275 km2 area and elevation range of 1125-3500 m) located at the headwater of Euphrates River, one of Turkey's most important rivers, is selected as the applicati...

Data driven models such as Artificial Neural Networks (ANNs) became a very popular tool in hydrology for a long time, especially in rainfall–runoff modelling. However, it does not have common usage in mountainous catchments, where snowmelt plays an important role, due to lack of continuous snow observations. In order to improve the accuracy of snow...

Short-term operation of reservoir systems is challenging due to conflicting objectives and constraints as well as the need for taking robust decisions in real-time. This study compares simulation and optimization based decision support techniques in application to the mitigation of flood events. Two models are employed in the study to support the o...

Alternative techniques to generate streamflow provides more robust model sets for mountainous basins where there is data and model uncertainty due to harsh topography and atmospheric conditions. Dedicated satellite data have extensively increasing potential in water resources and using them in short and long term analysis will provide better unders...

This paper demonstrates the basin/reservoir system integration as a decision support system for short term operation policy of a multipurpose dam. It is desired to re-evaluate and improve the current operational regulation of the reservoir with respect to water supply and flood control especially for real time operation. The most innovative part of...

Due to the increase in water demand and hydropower energy, it is getting more important to operate hydraulic structures in an efficient manner while sustaining multiple demands. Especially, companies, governmental agencies, consultant offices require effective, practical integrated tools and decision support frameworks to operate reservoirs, cascad...

Conceptual hydrological models are widely used for operational and scientific water resources management applications in mountain catchments. However, current model-based forecasting approaches are jeopardized by input data and model uncertainties. Data assimilation provides a suitable tool to merge information from remotely sensed observations and...

Contribution of snowmelt and correspondingly snow observations are highly important in mountainous basins for modelers who deal with conceptual, physical or soft computing models in terms of effective water resources management. Long term archived continuous data are needed for appropriate training and testing of data driven approaches like artific...

The aim is to operate Yuvacik Reservoir without any flood and drought risk for long-term water supply, to raise the reservoir elevation as high as possible before the inflow recession period starts, which is generally observed in early May. User-defined operating rules are determined, taking hydrological conditions (snow potential, inflow, season a...

Forecasting streamflow mainly due to snowmelt in the mountainous eastern part of Turkey is important in terms of effective management of water resources at the headwaters of Euphrates River, where large dam reservoirs are located. Monitoring Snow Covered Area (SCA) and modeling snowmelt forms the backbone of the forecasting studies as the snowmelt...

Effective management of a controlled reservoir system where it involves multiple and sometimes conflicting objectives is a complex problem especially in real time operations. Yuvacık Dam Reservoir, located in the Marmara region of Turkey, is built to supply annual demand of 142 hm3 water for Kocaeli city requires such a complex management strategy...

Hydrologic models have the importance in runoff forecasting especially for reservoir management. Implementation of a hydrologic model for real time forecasting is a challenging task, since it requires selection of convenient model parameters besides numerical weather prediction data to forecast runoff. In this study, seasonal parameter sets, develo...

Discharge forecasting by using a hydrologic model is one of the ways to cope with flood events since it provides managers take early decisions to minimize the risk of flooding. In this study, a conceptual hydrologic model is selected and applied with a series of calibration and validation steps to develop a decision support system for the reservoir...

Yuvacik Dam Reservoir Basin, located in the Marmara region of Turkey with 248 km2 drainage area, has steep topography, mild and rainy climate thus induces high flood potential with fast flow response, especially to early spring and fall precipitation events. Moreover, the basin provides considerable snowmelt contribution to the streamflow during me...

Streamflow occurring mainly due to snowmelt during spring and early summer months in the mountainous eastern part of Turkey is important as it constitutes approximately 2/3 of total annual volume of runoff. For this reason, modeling the runoff due to snow melting in Euphrates basin, where large reservoirs are located, forms the backbone of the fore...

Monitoring snow covered areas and modeling snowmelt play an important role in predicting runoff especially in regions where snow is an important resource. Snow cover can be analyzed both temporally and spatially with snow cover depletion curves of an area. Besides, some commonly used hydrological modeling programs such as SRM (Snowmelt Runoff Model...