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Effect of Spatial Resolution of Digital Elevation Model on the Estimation of Geomorphological and Geomorphoclimatic Unit Hydrographs in Amameh Watershed, Iran
F. Esmaeili, M. Vafakhah, V. Moosavi,
Volume 27, Issue 1 (5-2023)
Abstract
Digital elevation models (DEMs) are one of the most important data required in watershed modeling with hydrological models and their spatial resolution has a significant impact on the accuracy of simulating hydrological processes. In the present study, the effect of spatial resolution of five DEMs derived from the topographic map (TOPO) with a scale of 1:25000, ALOS PALSAR, ASTER, SRTM, and GTOPO with a spatial accuracy of 10, 12.5, 30, 90, and 1000 m, respectively, on the estimation of parameters of geomorphological and geomorphoclimatic unit hydrographs models has been evaluated in Amameh watershed. Thirty-four single flood events were used during the years 1970 to 2015. The results showed that in the GUH method, the application of the TOPO and ALOS PALSAR DEMs had the best results with root mean square error (RMSE) of 1.7 and 1.8 m3/s and Nash-Sutcliffe Efficiency (NSE) of 0.4 and 0.3, respectively. While the GTOPO DEM had the least efficiency with RMSE of 2.8 m3/s and NSE of -2. Similarly, the lowest and highest RMSE in the GCUH method belonged to TOPO and GTOPO DEMs with RMSE of 3.8 and 18 m3/s and NSE of 0.2 and -6, respectively. Generally, the GUH method had more favorable results than the GCUH method in all DEMs.

Assessment of Physical and Hydraulic Properties of Three Rockwool Types in Comparison with Wheat Straw and Sawdust as Greenhouse Growth Media
Sh. Shahmansouri, M.r. Mosaddeghi, H. Shariatmadari,
Volume 27, Issue 1 (5-2023)
Abstract
According to the rapid population growth, the challenging issue of production of economic and suitable food sources has led to greater attention to soilless culture greenhouse production systems. Components of growth media in horticulture are usually selected based on physical and chemical properties and their abilities in providing enough water and oxygen for roots. This study was conducted to investigate the feasibility of using some agricultural wastes (i.e., sawdust and wheat straw) and three rockwool types (i.e., raw, ground, ground, and sieved) as substitutes for commercial greenhouse growing media such as cocopeat and perlite. Several hydraulic, aeration, and chemical properties including easily available water (EAW), air after irrigation (AIR), water holding capacity (WHC), water buffering capacity (WBC), saturated water content (θs), bulk density (BD), total porosity (TP), water drop penetration time (WDPT), pH, and electrical conductivity (EC) were measured and scored in the growth media. Raw rockwool had larger particles compared to ground rockwool, which resulted in its faster water release. Processing of the rockwool decreased the saturated water content and saturated hydraulic conductivity due to the decrease in particle size. Four growth media were scored as very good and one was scored as good. The highest and lowest scores belonged to sawdust (34) and ground rockwool (30), respectively. The studied growth media with high TP, EAW, and WHC and low BD, EC, and WDPT can be used individually or combined with other commercial substrates for greenhouse growth media.

Investigation of the Effect of Electrokinetic Process on the Seepage Reduction, Increase of Failure Time, and Decrease of Seepage Level in the Clay Core of Earth Dams
S. Salehi, A. Mahmoodi Moghadam,
Volume 27, Issue 2 (9-2023)
Abstract
The present study investigated the related parameters to decrease the seepage through homogenous and heterogeneous earth dams by employing experimental models and solutions. Two heterogeneous earth dam models with vertical clay cores were considered to illustrate the effect of the electrokinetic application on the time failure factor. The seepage lines were measured along the longitudinal section from the heel to the toe using the observation wells by adjusting the electrodes of the electrokinetic application through the vertical clay core. The initial comparison expounds that adjusting the electrokinetic approach can decrease the level of the seepage line due to depleting water by considering horizontal drainage. Furthermore, the failure time was increased by 18 percent due to inputting the voltage in the clay content. The results indicated that the models with an electrokinetic approach were stabilized more than the ones. The hydrographs of the flow discharge were measured along the experimental tests to investigate the effect of electrokinetics with and without electrodes in 10 and 20 clay percent of the dam soil content. Results indicated that employing the electrokinetic application due to increasing clay content caused the effect of the electrokinetic was significantly increased and it caused the discharge flow reduced of 32 percent.

Hydrological Drought Monitoring Based on the Correct Calculation of Standardized Flow Index in the Karkheh Basin
S. Gholizadeh Tehrani, S. Soltani Koupai, R. Modarres, V. Chitsaz,
Volume 27, Issue 3 (12-2023)
Abstract
Drought is one of the most destructive and important climate phenomena, whose effect is usually more important on a regional scale. The importance of this phenomenon is more evident in the Karkheh basin due to its size and important role in providing the country's water resources. We aim to monitor hydrologic drought using the accurate calculation of standardizes streamflow index (SSI) in one month time scale based on fitting frequency distribution to monthly data and goodness of fit test for each station in Karkheh basin for 30 years (1986-2016). The findings of this research showed that the generalized Pareto distribution was selected as the most appropriate distribution in most months, unlike the previous research that fitted and used only the Gama distribution on the data. The time series of the standard flow index indicated the occurrence of super-drought in 2008 to 2015 years. Also, the significant impact of the construction of hydraulic structures upstream of the basin on the average flow rate was observed in some stations. The results of direct and annual monitoring of the drought situation showed that the Karkheh basin has experienced hydrological drought in recent years, and the drought trend is increasing.

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