فصلنامه حفاظت منابع آب و خاک
سال ششم شماره 3 (پیاپی 23، بهار 1396)

Soil resource conservation requires management approaches and provides appropriate solutions that can be achieved by knowing nature of rock units and relative importance of main sediment sources. The aim of this study is to determine hole of each lithological unit in sediment generation and to recognize their erosion conditions. For this purpose after sampling the sediment source and sediments of waterways of Kiov-chai Watershed, grading was performed for all samples by dry sieving. Then, 600 micron and 4 mm sieves were selected as indicators and by choosing 100 grains of sediment from each sample, mineralogical analysis was performed using a pair of binocular and considering mineral and rock fragments the results were compared with and adapted to the lithological units and the share percentage of each stone, was determined by counting the number of minerals and rock fragments. The results showed, Qvl lithological unit has the highest share in sediment yield with a 45.51 percent and has the very severe erosion status with total erosion index score with a 1053.14 which can be justified completely due to extensive degradation and its spread on both sides of the main river. After Qvl lithological unit, Qds2 and Qvb lithological units have the highest share in sediment yield with a 30.87 and 10.54 percent, respectively and Qtasllithological unit has the lowest share in sediment yield with a 45.51 percent.

In order to assess the uncertainty of climate change and its effect on the discharge into the Jamishan dam located in the northwestern province of Kermanshah changes in temperature and precipitation parameters in the periods 2020-2039 and 2040-2059 were calculated using a combination of weighted average seven climate model output under three emission scenarios A1B, B1 and A2 respectively, The daily rainfall and temperature forecasts for future periods under each climate scenario was entered to rainfall-runoff calibrated and validated model ‘IHACRES’ and the daily runoff of future periods under each scenario was predicted. In order to determine periods of high-water and water shortage in the status quo and future periods, using Markov chain transition probability matrix, the Frequency months of wet, normal and drought were calculated. The results showed that in the period 2020-2039, annual rainfall decreases and temperature increases. In the period 2040-2059 the annual temperature changes are most severe between -0.66 and °C. A1B and B1 scenarios show annual rainfall and runoff reduction and increase in the A2 scenario.

Headcut erosion is a sudden change in height or slope that makes gullies and valleys and may change within a height ranged from less than one centimeter to several meters depending on several factors and upstream movement. Occurrence of headcut erosion phenomenon in the rivers will result in bed erosion and instability of beaches. As a result, the river is widened and the outcome of the phenomenon is the transfer of large amounts of sediment downstream and dams’ reservoirs. Five adhesive soil samples including, clay and silt with different mixture percentages were examined and tested for 25% upstream and 5% downstream slopes for discharge, velocity and depths of several flows in the study. Volume of the produced sediment was measured in terms of real time and average. In addition, headcut rate and sediment discharge were measured. Some of the phenomena observed in the study that played an important role in the production of sedimentation volume and headcut rate include occurrence of hydraulic jump at the junction of steep slope to mild slope, tensile cracks on the soil surface and increased slope of bed during the experiment due to erosion. According to the results, changes in the three parameters of the amount of silt, upstream slope and flow rate are directly related to the increased rate of movement of sediments and headcut velocity. In pure clay, by increasing flow velocity 1.5 times the average volume of sediments, 13% headcut velocity and sedimentation discharge increased to 40% and 21%, respectively. Moreover, 50% increase of silt increased the average sediments volume, headcut velocity and sedimentation discharge by12%, 38% and 19%, respectively.

Optimum operating of reservoir dams is one of the most important challenges in the water resources management. In fact, integrated water resource management is necessary for an optimum and efficient operating of these resources. In this research the performance of differential evolution algorithm is compared with the improved harmony search algorithm and nonlinear programming method in optimized operating of the Eleviyan single reservoir dam on Soofi-chay River which is one of the most important dams in the Urmia lake basin. Considering the vital importance of the ecological flow to prevent the death of Urmia Lake, an optimization model is developed to determine the minimum required ecological flow of the Soofi-chay River, besides to the water flow needs such as the municipal, industrial demands, and also minimizing the water shortage for agricultural targets. The reservoir parameters including reliability, vulnerability and sustainability indicators are used to evaluate the performance of the studied algorithms in an optimal utilization of the reservoir. The results showed that using the differential evolution algorithm gives a higher-performance compared to the other methods employed in this study in efficient operation of the Eleviyan dam system.

Plunging pools are constructed at the downstream of dam spillways to dissipate the excess energy. The turbulent flow velocity converts to the dynamic pressure due to impact of flow with the pool’s bed. The aim of this research is to determine impact pressure of a vertical jet on plunging pool bed. Hence, the experiments were carried out in four different discharges (ranging from 6 to 27.5 lit/s according to the nozzle diameters), three jet diameters including 4.3, 5.2 and 8.2 cm and four falling heights of 37, 60, 90 and 120 cm. Also the experiments are conducted in similar flow conditions for smooth and rough surfaces, and results are compared. Dynamic pressures were measured with a pressure transducer. The analysis of data showed that increase of jet diameter causes decrement in the dynamic pressure coefficient. Results revealed an increase in dynamic pressures due to roughness of contacting surface. Moreover, variations of jet Froude number and fall length have significant effects on the dynamic pressure coefficient. The impact pressure was the highest in the surface center and was gradually reduced in outer zones.

Assessing the status of a regional salinity is considered as an important step in land management. This study was performed on part of Turkmen Sahra Lands in Golestan Province with Aridic soil moisture regime, in order to evaluation of salinity changes during the years of 1355, 1368 and 1392. For this purpose, two geostatic methods (ordinary kriging and cokriging) and four algebra methods (Inverse distance weight, Radial basis function, Global polynomial interpolation and local polynomial interpolation) were used for estimating the amount of salinity in depths of 0-50, 100-50 and 150-100 cm. The results showed the percent of land with more salinity than 32 dS/m has increased from 8.95 percent in 1976 to 45.22 percent in 2013. It seems during the 37- year management period, the improper utilization and collection from water and soil resources have led to increase in salinity of the soil. Therefore, so it is suggested to use various methods and appropriate management proceedings to monitor and control the process of increase soil salinity in the region.

This study was conducted to investigate impacts of deficit irrigation on trend of crop growth, quantity and quality characteristics and water use efficiency of maize in Kermanshah. The field study was carried out at a randomized complete block design with four irrigation treatments (40% deficit irrigation, 20% deficit irrigation, full irrigation (FAO Penman-Monteith method) and 20% over irrigation) and three replications with furrow irrigation method. Results indicated that impacts of deficit irrigation was significant on grain yield, biomass, weight of stems, weight of ears, weight of leaves, leaf area index, plant height, number of kernels per row, number of kernels per ear, grain protein and fat. The impacts of water stress on characteristics of maize were different in different stages of growth and were higher at the end of the growing season (grain filling stage). Maximum amount of water use efficiency in grain and fat was in T4 respectively 1.051 and 0.0549 Kg/ha and for biomass and protein was in T3 respectively 2.568 and 0.092 Kg/ha. So deficit irrigation is not recommended for maize in Kermanshah.

One of the mechanisms of solute transport in soil is preferential flow or flow in macropores. In this study, to investigate the influence of macropore paths on solute transport, three soil bulks composed of 3% clay, 4.2% silt and 92.8% sand in a box with 200 cm length, 100 cm width and 45 cm height were used. The first soil bulk was homogeneous (without macrpore path), the second one contained soil and layers of 5 cm thickness, composed of gravels with 2-4 mm diameter, from surface to bottom of the box (with continuous macropore layers), and the third one contained also contained soil and layers of same thickness and material, but the layers extended only to a depth of 35 cm (with non-continuous macropore layers). The transport of NaCl solution in these three soil bulks were experimented and then simulated using GeoStudio. In the soil bulk having continuous macropore layers, in comparison with the one with no macropore layer, the solute traveled the distance between the surface and the bottom in a shorter time (about 27%) and the peak concentrations were sooner observed (10-20 min). However, the non-continuous layers had no significant impact on the speed of solute transport. The GeoStudio software satisfactorily simulated the solute transport with the coefficient of determination more than 0.970 and the values of the root mean square error less than 0.25.

Lead (Pb) is an environmental pollutants and cause of serious effects on human health due to the properties of accumulation, toxic and long-lasting. In this study, different water level management, including flood irrigation, control water level in 20 and 36 cm below the soil surface and intermittent irrigation in rice cultivation were studied on amount of available Pb in a soil and accumulation in shoot of rice plants. The experiment was performed under the completely randomized design and with three replications at Shahrekord University. The results showed that the effect of irrigation management on the amount of available Pb in soil and accumulation in shoot was significant (p