This study has reached to that ANN (5-9-1) (five neurons in input
layer_nine neurons in hidden layer _ one neuron in output layer) is the
optimum artificial network that hybrid system has reached to it with
mean squared error equals (1*10^-4) (0.7
m3/sec), where this software
has summed up millions of experiments in one step and in limited time, it
has also given a zero value of a number of network connections, such as
some connections related of relative humidity input because of the lake
of impact this parameter on the runoff when other parameters are
avaliable.
This study recommend to use this technique in forecasting of
evaporation and other climatic elements.
Weather forecasting (especially rainfall) is one of the most important and challenging
operational tasks carried out by meteorological services all over the world. Itis furthermore
a complicated procedure that requires multiple specialized fields o
f expertise.
In this paper, a model based on artificial neural networks (ANNs) and wavelet Transform
is proposed as tool to predict consecutive monthly rainfalls (1933-2009) taken of
Homs Meteorological Station on accounts of the preceding events of rainfall data.
The feed-forward neural network with back-propagation Algorithm is used in the
learning and forecasting, where the time series of rain that detailed transactions and the
approximate three levels of analysis using a Discrete wavelet transform (DWT).
The study found that the neural network WNN structured )5-8-8-8-1(, able to predict
the monthly rainfall in Homs station on the long-term correlation of determination and root
mean squared-errors (0.98, 7.74mm), respectively.
Wavelet Transform technique provides a useful feature based on the analysis of the
data, which improves the performance of the model and applied this technique in ANNmodels
for rain because it is simple, as this technique can be applied to other models.
The relationship between precipitation and surface runoff is one of
the fundamental components of the hydrological cycle of water in
nature and is one of the most complex and difficult to understand
because of the large number of parameters involv
ed in the
modeling of physical processes and the breadth of parmetry and
temporary change in basin specifications. Multiple rainfall models
Modeling the relationship between precipitation and runoff is very
important for engineering design and integrated water resources
management, as well as flood forecasting and risk prevention.
The evaporation is one of the basic components of the hydrologic cycle and it is
essential for studies such as water balance, irrigation system design and water resource
management, and it requires knowledge of many climatic variables. Although, th
ere are
many empirical formulas available for evaporation estimate, but their performances are not
all satisfactory due to the complicated nature of the evaporation process. Accordingly, this
paper is an attempt to assess the potential and usefulness of ANN based modeling for
evaporation prediction from HAMA by using temperature, relative humidity and wind
velocity. The mathematical model was built by the (nntool-box), which is one of the
MATLAB tools. The feed forward back propagation network with one hidden layer has
been utilised to construct the model. Different networks with different number of neurons
were evaluated. Root Mean Squared Error (RMSE) was employed to evaluate the accuracy
of the proposed model. The study shows that ANN (3-14-1) was the best model with
RMSE (21.5mm/month) and R2 (0.97).
This study suggests using other types of neural networks for estimation of
evaporation
