a. nasseri

The selection of precision value for Roughness coefficient (RC) is necessary to design and utilize earth canals due to the vast distribution of Echinocola crus-galli in earth canals. Therefore, the current study was conducted to evaluate roughness coefficients in earth canals with Echinocola crus-galli at the Moghan plain (in the North-west of Iran). In the network of Moghan, 42 canal sections were selected to measure vegetation density and wet weight, water flow velocity (with a flow meter), and canal cross sections (with profilimetery devices). The hydraulic characteristics were estimated after water depth measurements. The Manning roughness coefficient (n) was applied to estimate the roughness coefficient. Path analysis was applied to identify the factors affecting the roughness coefficient. Multivariate cluster analysis using Ward's method and squared Euclidean distance was applied to cluster factors affecting the roughness coefficient in canals. The results revealed that RC averaged 0.015. The path analysis showed that the wetted perimeter, crop biomass, flow cross-sectional area, flow velocity, and hydraulic radius had the highest total effect on the roughness coefficient, respectively. The factors clustering showed that two clusters were obtained in the Euclidean distance of 11. The first cluster included flow velocity, crop biomass, flow rate, and bed slope; and the second cluster included flow cross-sectional area, wetted perimeter, and hydraulic radius. The findings could be helpful for designing and operating canals in the studied or similar regions.

Since most of the geochemical data analysis procedures require preliminary assumptions that lead to constraint and errors in the true nature of the data causing reduction in the effectiveness of the adopted methods. Therefore, a model-based clustering method as self-organizing map (SOM) were employed with the aim of recognizing Cu-Au mineralized zones by establishing an optimized exploration tool in Valezir area, NW of Iran. SOM as a dimension reduction method was introduced to recognize geochemical distribution patterns of Cu-Au with higher certainty while preserving the originality of the data. Subsequent to data preprocessing and testing different SOM architectures, an appropriate structure with a pattern containing six clusters was selected. Accordingly, the related elements distribution model was extracted and interpretation of the geochemical system represents two significant sets of elements in clusters (i.e. 1st, 2nd and 6th clusters) to anticipate the mechanism of distribution: 1- Copper and pertaining trace elements formation from intermediate to acidic hydrothermal solutions, which are localized in the northern part of the area and emplaced in the quartz monzo-dioritd intrusive body. 2- Au Anomalies and its associated elements As, Hg and Bi depicted in 2nd cluster. The Au anomalies follow geochemical pattern with Bi, Sb, As, and W that are mostly elongated from NW to SW of the area. It seems relatively the low enrichment of gold has occurred during the intrusion of the igneous body into older volcanic units that caused extensive alterations, remobilization and localization of Au and related elements. To assess the SOM results, a comparative study was carried out with the results obtained from hierarchical clustering analysis (HCA). The results illustrated higher performance by SOM approach in characterizing geochemical system and detecting the elements paragenetic sequence in the area for locating the exploration targets.

Stomatal conductance is one of the important indices to assess water deficit stress in plants. To evaluate stomatal conductance in corn leaves for scheduling irrigation, an experiment was conducted at East Azarbaijan Research Center for Agriculture and Natural Resources. The experiments were as Randomly Complete Blocks with three replications and with treatments of a: full irrigation, b: deficit irrigation from stages of 6-7 leaves to the end of ripening with full irrigation at flowering stage, c: deficit irrigation from stages of 6-7 leaves to the end of ripening with full irrigation at dough stage. The stomatal dimensions were determined by copy method. Stomatal conductance was measured along a leaf with different distances, at different leaves of a plant and at before and after irrigation events by a porometer. Results showed that the stomatal along a leaf and at leaves of a plant had a variable value. So that the stomatal conductance increased with increasing distance from petiole to leaf tip and with an increasing leaves number for soil surface to the canopy. The stomatal conductance changes along the leaf and its variability in leaves numbers were modeled as Logistic functions. The temperature variability along leaf was modeled as Sinusoidal function. Results also showed that the stomatal conductance from irrigation treatments were different. The stomatal conductance from two days after irrigation were similar and averaged 0.31 ms-1. The suitable time for irrigation and its cutoff were at stomatal conductance of 0.21 and 0.33 ms-1.

Implement of pressurized irrigation systems within the farms are not possible in some provinces of Iran, due to high cost of energy supply, evaporation and wind-drift losses, salinity conditions and ownership patterns. Therefore, the appropriate option is the application of low- pressure irrigation systems. The low- pressure system is a series of tubes that are supported by the canal, water tank or pumping station and distributes water to the farm ditches with a low pressure. The history, advantages and challenges of the application of low-pressure irrigation systems and some extension approaches are mentioned in this study. The major advantages can be referred to the reducing water conveyance time, increasing the irrigation efficiency, decreasing energy losses, preventing pollution of groundwater resources, controlling human diseases and reducing the cost of maintenance and applications. The challenges of application of low- pressure irrigation systems include the more complication relative to open irrigation systems, the inability of designer engineers to design and implement systems, the need for higher hydraulic height, and impossibility for monitoring water flow in the distribution system. It highlighted the importance of factors of design and implementation of low - pressure systems such soil and water characteristics; cultivation pattern and water requirements; irrigation management; design of border, furrows and basins dimensions; design of conveyance lines and pools; design of gated pipes; irrigation scheduling; maintenance procedure; cost of project implementation; economic evaluation; project management ; dimensional design; and design criteria for surface irrigation methods