فهرست مطالب بهزاد عادلی

It is necessary to be aware of the destructive factors in the ecosystem. These factors cause shelter and biomass destruction, thus decreasing species diversity. Livestock over grazing is one of the most physical destructive pressures on rangeland that leads to a decrease in diversity and vegetation elements. The aim of this study has been conducted to investigate the effect of different grazing intensities on the diversity and richness of plant species in the semi-arid rangelands of Mohammad Abad area of Jiroft, Kerman Province, Iran.

We selected 3 sites that included light, moderate and heavy grazing intensities. Sampling was performed using 90 plots (2 m2) along 18 transects. The list of specie, canopy coverage and number of individuals per species were recorded for each sampling unit. To evaluate diversity and richness of the plant species, Margalef and Menhing richness indices, and Simpson, Shannon, Hill N0 and Hill N1 diversity indices were calculated. SPSS software was applied for data analysis. Comparison of different indices of diversity and richness among study sites was performed by the Tukey test.

The results of Margalef richness index showed significant differences between all grazing sites. No significant difference existed in the Menhing richness index of different grazing categories (p<0.01). Results of calculations of diversity indices for Simpson, Shannon, Hill N0 and Hill N1 showed that there were significant difference (p<0.01) between all grazing sites.

Generally, diversity and species richness indices due to low rainfall and placement in the semi-arid region are relatively low in the case study. Therefore, because of the sensitive and fragile nature of these types of rangelands in the operation, we should pay more attention to prevent further destruction and amended the composition.

Groundwater resources play a vital role in the development and sustainability of a territory. Therefore, in areas with low and irregular precipitation and limited access to surface water resources, the management of groundwater resources, in terms of quantity and quality, is the inseparable part of sustainable development. In the present study, principal components analysis (PCA) was used to assess the quality of groundwater resources of Behbahan Plain, Khuzestan province, Iran. In order to perform a groundwater quality analysis, 12 hydro-chemical variables were selected in order. Results of the KMO index and the Bartlett's test illustrate that this is reasonable to use the PCA on the dataset, which is constructed based on the selected variables, for characterization and analysis of groundwater quality in the study area. According to outcomes of the PCA, the first two axes (PC1 and PC2) captured 85.31% of the total variance in the dataset. The first PCA axis (PC1) explained 76.68% of the variation in the hydro-chemical data that was mainly affected by 10 variables (TH, SAR, K, Na, Mg, Ca, Cl, SO, TDS and EC). The second component (PC2) contributes 8.622% of the total variance in the dataset that indicated strong positive correlation with HCO3 and negative correlation with pH. Also, in this study, the relationship between spatial variation of each selected variable and land use were investigated.

Lack of sustained access to water resources will lead to social disputes and economic disruption. This issue is currently one of the serious problems in Sarkhoon watershed, Hormozgan province. In this regard, the WQI method and the Man-Kendall test have been used to determine the water quality class andto observe the trend in the studied variables, respectively. The results showed that a significant and definite decrease in the quality and level of groundwater in the Sarkhoon plain. The obtained trend for declining water level in the plain had a coefficient of variance of 0.03 and S-Mann-Kendall statistic of -277 at 99.9% significance level. The slope of trend obtained for water level drop and the increase in WQI values, which indicates a decrease in water quality, were -33.3 and -42.3, respectively. The reported values for the slope of trend represent a decrease of 33 centimeters and an increase of 3/4 WQI unit per year.

Surface. The development of gullies causes the loss of a great amount of soil and could be considered as one of the principal causes of geo-environmental degradation. In this research FAZI model introduced for gully erosion zonation in arid and semiarid area considered to calibration and validation in Kahkiloeh and Boyerahmad Province. Therefore, the ABGANDI watershed were selected by consideration of gully erosion distribution in Kahkiloeh and Boyerahmad Province. In this region the maps of lithology, slope, soil, rainfall, land cover and land use were extracted and thus selected the working units. In each of the units, gullies morphometric, soil penetration condition and soil conservation percent characteristics with survey investigated. Also, determinates the quantity value of six maps model input layer include (lithology, percent of slop, soil type, annual average precipitation, land use and percent of soil conservation) was determined. Finally, gully erosion mapping using overlay index, fuzzy algebraic sum, fuzzy algebra product and fuzzy gamma in GIS performed. Obtained result of different regions indicated that the fuzzy gamma model 0.8 is the proper method to gully erosion zoning in studied watershed.

Regression equations of sediment rating curves are too biased due to the logarithmic of the discharge and suspended sediment data. In this study, correction coefficients were used to improve the results of river sediment estimation methods in Bashar and Zohreh hydrometric stations with different indices of accuracy and precision. The present study aims to evaluate the performance of five methods of rating curve including FAO, MVUE, QMLE, LRC, Ls in the case of intermediate categories and no category situations. Root mean square of error and coefficient of efficiency indicators were used to evaluate the performance of sediment rating curves and to choose the best of them. Results of root mean square of error and coefficient of efficiency indicators computation indicates that in the Bashar station LQMLE method is provided maximum coefficient of efficiency (CE=92) and the minimum error (RMSE=0.38) and LS method had the lowest coefficient of efficiency and highest error (CE=86 and RMSE=0.94). In normal state the same results has been obtained. Zohreh station correction coefficients results showed that the maximum coefficient of efficiency is related to LQMLE (CE=95) and FAO had lowest coefficient of efficiency and the highest root mean square of error (CE= -1.58 and RMSE=2.48). In normally condition the LRC method has achieved maximum coefficient of efficiency and minimum error (CE=95) and (RMSE=0.53). On the other hand, amongst the different methods, LS is provided the lowest coefficient of efficiency and the highest root mean square of error (CE=-7 and RMSE=3.88). In general, by application of different methods and different correction coefficients of sediment rating curves in cases of non-classified data and the intermediate state, concluded that in most models the LQMLE and LRC is the best method of calculating sediment.