

Articles
by
M.H. Mahdian 
Total Records (
5 ) for
M.H. Mahdian 





R. Sokouti
and
M.H. Mahdian


This research was conducted to study spatial distribution of soil nutrients including nitrogen, phosphorus and potassium and to compare the efficacy of various geo statistical approaches in the estimation of these nutrients and the preparation of spatial variability maps of these elements aimed to righteous management of fertilizers in Urmia plain, West Azerbaijan Province, Iran. To estimate the rates of soil nutrients including nitrogen, phosphorus and potassium of nonsampled areas, the Kriging, Cokriging and Weighted Moving Average methods were used in a GIS system, instead. To compare these methods, crossvalidation method with two statistical parameters Mean Absolute Error and Mean Bias Error were applied. Present studies implied that Kriging method has the least MAE of 0.450 and MBE of 0.025. This method with correlation coefficient of 0.99% and Gaussian semi variogram was of high preciseness in the estimation of nutrient rates in the points with no former information available. The estimation error in this method ranged between 0.18 and 0.75 and its deviation was between 0.002 to 0.12 meq/100 g of soil. 





R. Sokouti
and
M.H. Mahdian


The present research was conducted to analyze spatial
changes in soil salinity distribution as an aspect of soil degradation
and to compare the efficacy of different Geostatistical methods in its
estimation and the preparation of maps of the spatial distribution of
soil salinity. To estimate soil salinity of nonsampled areas, the methods
of Kriging, CoKriging and Weighted Moving Average were applied in Geographical
Information System (GIS) medium. To evaluate the efficacy of the methods,
the crossevaluation approach with two statistical parameters of mean
bias error and mean absolute error was taken in practice. Results indicated
the high precise of Kriging method with regression coefficient of 0.98
for the estimation of salinity rates in the areas, for where no data were
available before. Estimation error for this method was 1.31 and biass
was 0.34 dS m^{1} which indicates high accuracy of Kriging method
to estimate topsoil salinity and its precise. 




H. Zarrin
,
F. Sharifi
,
M. Vafakhah
and
M.H. Mahdian


In this research, to evaluating of low flow from data
of 28 hygrometry stations of Karkheh and Karoon basin, were analyzed and
then flow duration curve was drew and discharge of parameters includes
Q_{75%}, Q_{90%}, Q_{92%}, Q_{95%} and
Q_{99%} were calculated. Toward nomination of effective factors
on low flow 21 parameters was detected such as physiographic, hydro climatic
and geomorphologic, with geographic information system. With principal
components analysis method we chose components which has less correlation.
This component in regard of their importance include: weighted average
slop of catchment, area, average elevation of catchment, compactness coefficient
and slop of main channel which illustrate 80.5% of variation of data.
In continue regional analysis with multivariate regression to establish
relations between low flow and catchment’s characteristics. Finally
regard to comparing and assessment the accuracy of estimating methods,
we used 9 control stations data and then we compared the amount of discharge
of low flowon the base ofachieved models with the amounts of control
stations and finally the results shown that obtained models in this area
were significant (at 99% level). 




F. Rajabzadeh
,
E. Pazira
,
M.H. Mahdian
,
S. Mahmoudi
and
M. Heidarizadeh


The objective of this study was to study the desalination and desodification of sugarcane fields in Khuzestan plain. Leaching experiments were conducted on seven sites and intermittent ponding method was implemented for an applied water depth of 100 cm. Among four models fitted to desalinization and desodification estimations, an exponential model with a correlation coefficient of 0.735 and significance level at 1% was selected. In the second model, initial, final and equilibrium salinity, leaching efficiency and moisture content were considered and the fitted exponential model with R^{2} = 0.758 was determined as the best desodification. A simulation model called leaching process was developed to determine the amount of water and time needed for reclamation of the whole soils of the study area. Two scenarios were presented: scenario I contained initial leaching, barely cultivation and leaving plant residual during warm seasons, scenario II proposed initial leaching and heavy disk operation and then a preirrigation operation. Considering lowering consumed water depth for the soil reclamation and also higher yield in the first scenario, scenario I was selected as a best choice. 





M.H. Mahdian
,
R.S. Oskoee
,
K. Kamali
,
H. Angoshtari
and
M.A. Kadkhodapoor


Since, measuring infiltration rate directly is time consuming and expensive, the Pedo Transfer Functions (PTFs) were developed to estimate soil infiltration rate using soil physical data of the flood spreading stations in Iran. Infiltration rate was measured in the flooded areas by double ring method. Selected soil physical properties used as input variables were sand, silts, clay percentage, bulk density, field capacity and wilting point. Soils studied were classified as Entisols. All stations were classified into three groups using Principal Component Analysis (PCA). Linear and nonlinear PTFs were developed to estimate infiltration rate. For one variable linear regression, the PTFs at 0.95 confidence interval were obtained. Nonlinear regression developed as PTFs using gravel, sand, silt and clay percent. There were also developed the multi variable functions based on the gravel, sand, silt and clay percent, so it is possible that developing the related functions to estimate infiltration rate by easily measured soil parameters. Most of the developed functions were cubic. Changes in PTFs have wide variation and developed PTFs vary based on the number of parameters formed them. 





