Papers by Babak Vaheddoost
Theoretical and Applied Climatology, 2006
Precipitation as the main process that brings evaporated water from the oceans to the land's surf... more Precipitation as the main process that brings evaporated water from the oceans to the land's surface is a critical role player in Lake Urmia basin (Iran). As a hyper-saline lake declared as UNESCO's biosphere reserve in Ramsar Convention, it is dealing with gradual atrophy. In this study, characteristics of annual precipitation in the Lake Urmia basin are investigated by means of several statistical measures and tests. Data in 53 meteorological stations widespread across the basin for a period of 31 years from 1981 to 2011 are considered for analysis. Fundamental statistical characteristics of the data like mean, maximum, minimum, standard deviation, coefficient of variation, coefficient of skewness, coefficient of kurtosis, auto-correlation and cross-correlation coefficients of the annual precipitation are calculated. Entropy in each station is also calculated with respect to the long-run mean precipitation of the basin. Results of the analysis are plotted in contour maps. Several tests for consistency, randomness, trend and best-fit probability distribution function are applied to investigate characteristics of the annual precipitation. Heterogeneity and dependence on local conditions are the main results revealed by this study while consistency and dependency of precipitation on North West and West of the basin are considered as the most effective among other regions. Due to the North-South oriented mountains, a relatively sharp decline in the precipitation from West to East can be compared to the gradual decline in precipitation from North to South due to smooth change in the terrain. It is also seen that such characteristics as probability distribution, consistency, randomness, trend, and uncertainty of annual precipitation in the Lake Urmia basin become more complex as crossing from West to East than crossing from North to South on the basin.
Theoretical and Applied Climatology
Drought is a natural phenomenon that has environmental and socio-economical drawbacks. Especially... more Drought is a natural phenomenon that has environmental and socio-economical drawbacks. Especially in arid and semi-arid regions, human activities are closely linked to the water supply and agricultural water use. Although the consequences of drought are prolonged, immediate actions are needed in practice which urges the continuous need for drought monitoring. The present study addresses a regional frequency analysis (RFA) for extreme drought events including severity, duration, and magnitude over Iran. Standardized precipitation index (SPI) time series with 1, 3, 6, 9, and 12 moving averages are determined from 106 meteorological stations for the period 1993-2016. Using Ward’s clustering analysis, the drought characteristics are grouped into different clusters and their homogeneity is confirmed by the heterogeneity measure test based on the L-moment approach. The results of RFA indicate that both generalized Pareto (GP) and Pearson type 3 (PE3) distribution functions are the best-fi...
Hydrological Sciences Journal
Hydrological Sciences Journal
Environmental Science and Pollution Research
Theoretical and Applied Climatology
Journal of Innovative Science and Engineering (JISE)
Pure and Applied Geophysics
Flow Measurement and Instrumentation
Theoretical and Applied Climatology
Water Supply
A multi segment sharp-crested v-notch weir (SCVW) was used both theoretically and experimentally ... more A multi segment sharp-crested v-notch weir (SCVW) was used both theoretically and experimentally in this study to evaluate the length of the hydraulic jump at downstream of the weir. For this aim, SCVW with three triangular segments at different tail-water depths (tailgate angles), and ten different discharges at steady flow condition were investigated. Then, the most effective parameters on the length of the hydraulic jump are defined and several parametric and nonparametric regression models, namely multilinear regression (MLR), additive non-linear regression (ANLR), multiplicative non-linear regression (MNLR), and generalized regression neural network (GRNN) models are compared with two semi-empirical regression models from the literature. Results indicated that the GRNN model is the best model among the selected models. These results are also linked to the nature of the hydraulic jump and turbulent behavior of the phenomenon, which masks the experimental results with outliers.
Water Resources Management
Arabian Journal of Geosciences
There are numerous drought indicators used by decision makers all around the globe which have bee... more There are numerous drought indicators used by decision makers all around the globe which have been developed to fulfill specific needs. By far, risks associated with drought and related consequences have become a bold topic for scientists in which debates still taking place everywhere. No global drought indices could provide universally accepted results since almost all of these indices are based on observed data as key performance indicators. In this respect, researchers spend a lot of effort on this issue for a better understanding on the various indices which are proposed until now. It is crucial to get a better sense on how drought can develop and how it can be monitored. It is also important to understand that, recent global challenges like climate change also amplifies the obligation on continues effort toward developing better indicators and methods to monitor droughts. As climate patterns change or a seasonal shift occurs, predefined drought indicators become useless. In this review, the concepts of drought indices and indicators are revisited and evaluated. Pros and cons of frequently used indices are addressed and the major differences between them are bolded. It is concluded that each index is applicable to fulfill expectations of a specific drought type while pre-knowledge about each case is very crucial. However, there is a need to develop a composite drought index to integrate all relevant data and drought definitions, with respect to the dominant types of monthly droughts in time and space together with climate change scenarios.
Hydrological Processes
Being a large hyper‐saline water body, Lake Urmia in north‐western Iran deals with a gradual decl... more Being a large hyper‐saline water body, Lake Urmia in north‐western Iran deals with a gradual decline in its water level. Most of the studies on Lake Urmia have neglected the groundwater issue. In this study, as a direct approach, the interaction between the groundwater level and the lake water level is investigated both in time and space by analysing the groundwater data compiled from observation wells surrounding the lake. Baseflow separation is considered as an indirect approach to understand the groundwater contribution to the river network flowing into the lake. It is determined that about 70% of run‐off in the rivers draining into the lake is born in the form of baseflow. An interaction between the lake and the groundwater storage is clearly seen from the analysis to conclude that groundwater has a potential to recharge the lake. Thus, the shrinkage of water level in Lake Urmia could be expected to accelerate with the drastic use of groundwater, which will be a disaster with no return.
Hydrology, 2017
A method is presented to analyze the interaction between groundwater and Lake Linlithgow (Austral... more A method is presented to analyze the interaction between groundwater and Lake Linlithgow (Australia) as a case study. A simplistic approach based on a "node" representing the groundwater component is employed in a spreadsheet of water balance modeling to analyze and highlight the effect of groundwater on the lake level over time. A comparison is made between the simulated and observed lake levels over a period of time by switching the groundwater "node "on and off. A bucket model is assumed to represent the lake behavior. Although this study demonstrates the understanding of Lake Linlithgow's groundwater system, the current model reflects the contemporary understanding of the local groundwater system, illustrates how to go about modeling in data-scarce environments, and provides a means to assess focal areas for future data collection and model improvements. Results show that this approach is convenient for getting first-hand information on the effect of groundwater on wetland or lake levels through lake water budget computation via a node representing the groundwater component. The method can be used anywhere and the applicability of such a method is useful to put in place relevant adaptation mechanisms for future water resources management, reducing vulnerability and enhancing resilience to climate change within the lake basin.
During the past decades, human water use has more than doubled, yet available freshwater resource... more During the past decades, human water use has more than doubled, yet available freshwater resources are finite. As a result, water scarcity has been prevalent in various regions worldwide. Qanat, as a traditional structure is a drainage system of water table. Supporting the water level in water table, some efforts has been done mostly in countries which is located in arid or semi-arid zones. Consequently, an underground dam (UGD) as a familiar case, is a good option for such supporting plan. In this research, prediction of discharge, preserved by a Qanat string which is buried in an ephemeral river bed is mentioned. Later, the Qanat string is supported by simulation of constructing an underground dam. In order to achieve the desired goal, artificial neural network (ANN) techniques were applied versus multi linear regression (MLR). Using various but unprocessed input data (water level in wells, precipitation, evaporation etc.) model was considered with high uncertainty situation. Manipulating the model, different activation functions of feed forward back propagation (FFBP), generalized regression network (GRN) and radial base function (RBF) ANN models were used. Results indicate that GRN is the best technique providing the most accurate prediction with 3.78 of mean square percentage error (MSPE) among ANN methods, while MLR shares 3.51 of MSPE. In addition, FFBP model considering the log-sig activation function, is the poorest result with 42.2 of MSPE. It is concluded that, ANN techniques provides acceptable results for prediction of drainage in Qanat located in an underground dam's reservoir.
Uludağ University Journal of The Faculty of Engineering, 2020
Precipitation trends can be linked to large-scale climatic events or cyclic behaviors. However, e... more Precipitation trends can be linked to large-scale climatic events or cyclic behaviors. However, exploring these patterns in short data records can be problematic. In this study, the monthly precipitation time series recorded across the Bursa district in Turkey were addressed between January 2005 to October 2018. Stations with the minimum data loss and the longest time records in the region were selected for the analysis. Therefore, Osmangazi, Keles, Uludag, Gemlik, Iznik, Karacabey, and Mustafakemalpasa stations were selected. Linear trend (LT), moving average (MA), Mann-Kendall (MK), turn points (TP), Spearman rank-order correlation (SROC), innovative Şen (IS), innovative trend analysis (ITA), changes in distribution (CD), and standardized precipitation index (SPI) methods were used to detect short-term trends in the precipitation time series. Results indicated that the trends, reported by the previous studies could not be reproduced at a monthly scale when using LT, MK, SROC, IS, ITA, and MA. However, the trends observed by the SPI-48 were also tracked down using CD, and SPI methods. It is concluded that the detection of the short-term trends is problematic whilst the outliers deviate results of the analysis. Hence, a combination of CD, ITA, and IS methods is a key in evaluation of the short-term trends within a data run. Öz: Yağıştaki eğilimler, büyük ölçekli iklimsel olaylar veya döngüsel hareketler ile ilişkilidir. Kısa veri kayıtlarında bu davranışın incelenmesi sıkıntılı olabilmektedir. Bu çalışmada, Ocak 2005-Ekim 2018 tarihleri arasında Bursa ilinde ölçülen aylık yağış zaman serileri kullanılmıştır. Bölgede en uzun zaman kaydına ve en az veri kaybına sahip istasyon verileri analizlerde kullanılmak üzere seçilmiştir. Bu amaca yönelik olarak, Osmangazi, Keleş, Uludağ, Gemlik, İznik, Karacabey ve Mustafakemalpaşa istasyonları seçilmiştir. Seçilen istasyonların yağış zaman serilerindeki kısa dönemli eğilimlerini tespit etmek için doğrusal eğilim (LT), hareketli ortalama (MA), Mann-Kendall (MK), dönüm noktaları (TP), Spearman sıralı korelasyon (SROC), yenilikçi Şen (IS), yenilikçi eğilim analizi (ITA), dağılım fonksiyonundaki değişiklikler (CD) ve standart yağış indis (SPI) yöntemleri kullanılmıştır. Uygulanan analizler neticesinde, önceki çalışmaların ortaya koymuş olduğu eğilimlerin tek başına LT, MK, SROC, IS, ITA ve MA yöntemleriyle tespit edilemediğini göstermektedir. Buna karşın, SPI-48, CD ve SPI yöntemleri ise eğilimleri tek başına belirgin bir şekilde tespit edebilmektedir. Aykırı değerlere sahip olan verilerde kısa dönemli eğilimleri tespit etmek zordur. Aykırı değerler barındıran verilerde kısa dönemli eğilimlerin değerlendirilmesinde CD, ITA ve IS yöntemlerinin birlikte kullanılması önerilmektedir.
Journal of Innovative Science and Engineering (JISE), 2019
As an alternative resource to the surface water, groundwater is a vital resource that has been on... more As an alternative resource to the surface water, groundwater is a vital resource that has been on the interest of many recent studies. Hence, the evaluation of the groundwater potential, its properties, and its availability needs specific dedication. In this study, monthly groundwater level time series at 9 observation wells scattered aligned with Mount Uludağ in Bursa are used. A 12-year period starting from January 2007 to October 2018 is taken into analysis and several statistical properties of the groundwater level time series are projected on maps. These statistical values are mean, coefficient of skewness, coefficient of kurtosis, coefficient of variation, and correlation coefficient. Results indicate that there is a high potential in the groundwater flow towards Yeniceabat. A strong linear correlation between groundwater levels in wells was observed which shows the potential connectivity between aquifers in the region. In addition, the groundwater levels located at the north show irregular patterns, probably due to water withdrawal for agriculture purposes.
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Papers by Babak Vaheddoost