جستجوی مقالات مرتبط با کلیدواژه « پارامتر تصادفی » در نشریات گروه « آب و خاک »

Iran's water situation has reached a critical level due to frequent droughts and over-abstraction of water resources. Therefore, dealing with the optimal allocation of water resources in these conditions is an important and vital issue. In the present study, the model of water resources allocation in critical conditions has been developed and the proposed model has been implemented in Mashhad. The innovation of the proposed model of the present study is to consider the sustainability of water resources and simultaneously pay attention to the quantity and quality of water resources. In this study, considering the stochastic value of available water parameter, two-stage stochastic allocation model is presented and solved by the method of Goal Attainment, and implemented in MATLAB software. This model has been developed with the aim of maximizing the profits of different users, minimizing the allocation of saline water from the underground source and minimizing the shortage of water. The results of the study indicate that even in the wet scenario, available water resources cannot meet the demand of different sectors. If the stability index is maintained at 75%, the amount of water shortage in the drought scenario is equivalent to 501.75 MCM, in the normal scenario is equal to 358.75 MCM, and the in the wet scenario is equal to 78.75 MCM. In addition, the sensitivity analysis of the model with different data indicates that if in the drought scenario, the amount of available water from both surface and treated water sources is equivalent to 300 and 200 MCM, respectively, then the optimal allocation pattern has changed and the amount of water shortage that can lead to overdraft is 103.75 MCM.

Hydrological modelling is usually used as a tool for predicting watershed hydrological response by water resources planners in flood forecasting and water resources management. Identification of the Nash-cascade model parameters as a practical model in simulation of flood hydrograph is very important in watersheds with limited data. The aim of this study was determining the Nash model response to variations of input parameters ranges (number of reservoirs and storage coefficient), and best subset combination to simulate unit hydrograph in the Jafar-Abad watershed, Golestan Province. The forty three rainfall-runoff events were used to derive that index unit hydrograph of the study area using S-curve technique. Then, the response of the Nash model results output was assessed considering random generated n, and k parameters through 3220 synthetic simulation and model efficiency was assesses using Nash-sutcliffe criteria. The results showed that the model has produced acceptable results in different values of n, and k input parameters and the model efficiency were more than 0.6 with ranges of 10-30 for n parameter and 0.01-3 subset of k values. The response of the Nash model in higher k and low n value subsets, showed the perfect simulation results. Also the results indicates that the storage coefficient parameter had an effective influence on determination of optimal input model combination, while a suitable model results is possible in different values on (n) number of reservoirs. In conclusion, identification of a precise value for the storage coefficient can greatly improve the simulation results. The results and the used approach can be used to determine the optimal model response regarding input parameters in similar ungauged watersheds.