حفاظت منابع آب و خاک
سال:1398 | دوره:9 | شماره:2 |تعداد مقالات:17

The operation of fish ponds washing increases the risk of using these wastewater in drip irrigation by raising the amount of suspended solids and organic matter in the wastewater. In this paper, three drip irrigation treatments were performed. For each treatment, Netafim and Microflapper emitters were used with 4, 8 and 12 l/h discharges. During a season, 42 irrigation events were conducted with conventional water (as control) and fish farming effluent (with depletion and without depletion of tubes). Several samples were collected from wastewater, in the usual mode and in washing the fish ponds, in three replicates. The physical, chemical and biological properties of all samples were measured and compared. The filtered materials by sand and grid filters of the control and wastewater systems were analyzed by Master Sizer device. The results showed that washing has a significant effect on the concentration of suspended solids (P<1%) and the concentration of organic matter (P<5%). But the effect of washing on the concentration of nitrate and the number of bacteria in the wastewater is small and negligible. The results also showed that the discharge of 8 L/h Microflopper emitters had a significant correlation (P<1%) with pond washing in both effluent treatments, and the discharge rate of Microflapper emitters was more correlated with the washing operations compared to the Netafim emitters. The results also showed that the efficiency of grid filters are more than sand filters when fish farm effluent is using, and the presence of these filters is more necessary.

In this research, sprinkler irrigation network of Sysan area located in Bostanabad city in Azarbayjan Province was analyzed using WaterGEMS software. This irrigation network based on the position of the main, sub-main and lateral pipes divided into three A, B, and C zones and with regard to irrigation interval, the number of sets and sprinklers, 9 scenarios were defined. Hydraulic parameters (pressure and velocity) were analyzed in the nodes and the pipes before and after optimization with WaterGEMS, respectively. The hydraulic analysis indicated; based on the required pressure of the sprinkler operation (40 m-H2O) and the maximum supply pressure of the selective pump (70 m-H2O), there was no problem or limitation in supplying the network pressure. In the other words, the pressure aligned with standards. While according to permissible velocity in the sprinkler irrigation pipes, the critical velocities were observed in 4 scenarios in zone B and in 5 scenarios in zone C. By applying the necessary changes in the diameter of the pipes and provided that the pressure variations aligns with standards (less than 20%), the velocities were optimized and aligned with standards. Given that the hydraulic parameters were optimized by decreasing pipe diameter, the optimally designed system with WaterGEMS software led to a decrease of 7. 3% in costs compared to the designed and implemented system.

Agricultural practices may decline the quality of soils. Knowing the temporal changes of soil quality in the agriculture lands is crucial for optimal management of lands and to achieve the maximum economic efficiency. In this study, some physical characteristics of four cultivated soil were compared with neighboring non-cultivated soils as control treatments. A given site, four soil samples (including two soil samples from cultivated lands and the two soil samples from adjacent non-cultivated lands) were collected. Soil structural stability, soil moisture retention curves, particle size distribution and porosity of soil, mechanical strength, plant available water and aeration, relative field capacity, integral water capacity was measured. Generally, in the cultivated lands, soil organic matter content (1. 81 vs. 2. 70 %), soil structural stability (5. 2 vs. 7. 4), microporosity (0. 28 vs. 0. 39), field capacity (0. 27 vs. 0. 34) and permanent wilting point (0. 15 vs. 0. 20) water contents and plant available water content (0. 11 vs. 0. 15) were decreased (P ≤ 0. 05) in comparison with the uncultivated lands. However, the macroporosity (0. 39 vs. 0. 23) and soil sensitivity to crusting (0. 70 vs. 0. 57) were increased (P ≤ 0. 05) compared to the uncultivated lands. It could be concluded that agricultural practices decline the soil quality and there is a need to take measures to avoid their negative impacts through proper management.

With the fast-growing economy in the coastal regions, the demands for water resources and the exploitation of groundwater have been increased. Consequently, the established balance between freshwater and seawater has been disturbed and hence resulted in extensive seawater intrusion into groundwater. In this paper, the flow model and saltwater intrusion in the Sari-Neka aquifer is simulated using the GMS model. The model is calibrated for four years Between October 2010 and September 2014, both in terms of groundwater levels and TDS concentration. The calibrated model is validated for the next year in terms of groundwater levels and TDS concentration with the available data for October 2014 and September 2015. The values of the correlation coefficient in the steady-state model, transient model and validation model in the flow model are obtained 0/99, 0/98 and 0/97 respectively. The values of the correlation coefficient in the transport model are obtained 0/83 and 0/87 in the transient model and validation model, respectively. After the validated model and assuming all the hydrogeologic conditions remain, a predictive 6-year simulation run indicates that further seawater intrusion into the coastal aquifer can occur in the study area. The effects of the Gelvard dam on the quality of groundwater in the Sari-Neka aquifer in normal, drought and wet conditions also were investigated. The results show that under drought conditions the 50% iso-concentration contour movement for TDS will increase by 5/98 %. In wet conditions, the 50% iso-concentration contour movement will be reduced by 2/94%.

Surface irrigation is still main irrigation system in agricultural land, so it is necessary to finding a solution for improving these systems. Manning roughness coefficient and infiltration parameters are the most important parameters in evaluation of surface irrigation systems. Infiltration parameters play an essential role in the evaluation and design of irrigation systems; therefore, it is necessary to estimate these coefficients, accurately The purpose of this study was to estimate infiltration parameters and manning roughness coefficient in continuous and cutback flows during the first three irrigation events using INFILT, SIPAR_ID and EVALUE models. The results showed that the average relative error percentage in the INFILT, SIPAR_ID and EVALUE models were 16. 6, 5. 2 and 11. 2, respectively, and the maximum errors were 1. 6, 0. 7, and 1. 1 m3, respectively. The SIPAR_ID model has less error than the other two models. These models also had higher accuracy in estimating infiltration in the border irrigation than furrow irrigation. The US Soil Conservation Service (SCS) also proposed a Manning roughness coefficient for fallow furrows in the first irrigation 0. 04, which is very different from the estimated values of the SIPAR_ID model from 0. 038 to 0. 09.

Climate change is one of the major challenges affecting the natural ecosystems and various aspects of human life. The effects of global warming on the hydrology and water cycle in nature are very serious, and the quantitative recognition of these effects creates more readiness to deal with its consequences. In the present study, the 2010-2100 periods is predicted based on SDSM and ASD. Finally, the effect of climate change on the hydrological conditions in the Kan watershed is simulated using the ANN and IHACRES. The results of the study, while confirming the efficiency of both SDSM and ASD models in climate simulations and ANN and IHACRES in hydrological simulation, showed that the increase in precipitation (2-27%) and temperature (0. 3-4/4 C) is probable in future climate conditions for the 2010-2100 periods. Runoff changes in the upcoming period (2010-2039) show an increase (5-36 %) in the scenario of RCPs and a decrease (32-41%) in scenario A2. The high flow value in the upcoming period is increased, and the low flow decrease. Most changes were observed in spring. The results of research, while highlighting the importance of effects of climate change, make it essential to apply them for proper management in order to adapt to climate change in the future policies of the Kan watershed management.

Soil erosion management requires providing appropriate solutions that can be achieved with knowing soil erosion situation. The aim of this study, modeling rill erosion potentially by using maximum entropy (MaxEnt) and investigation of its robustness to knowing about rill erosion susceptibility in the Golgol watershed, Ilam province. To this purpose, different geo-environmental factors were selected to be employed in the modeling process. In addition, 157 rill erosion events were recorded by a global positioning system (GPS). These events were then classified into two classes of training and validation with a ratio of 70: 30. To evaluate model robustness, these classifications were repeated three times, and therefore, three sample datasets (D1, D2, and D3), were prepared. The area under receiver operating characteristics (AUC) curve was used for evaluating the performance of the model. Regarding the robustness results, all of the datasets obtained good AUC values and all of them were robust for both the goodness-of-fit (RAUC =1. 3) and prediction performance (RAUC =3. 1). In other words, the results demonstrated that the model remained quite stable when the calibration and validation data were changed. In addition, we found that the MaxEnt model is capable to produce rill erosion susceptibility map. Furthermore, based on the sensitivity analysis, it found that the most important components in rill erosion susceptibility modeling are lithology and distance from stream. The adopted methodology can be useful as an efficient approach for land use planning and erosion risk management.

By approaching towards Urmia Lake, the potential source of sand dust originating from the sand dunes can be clearly observed. Wind erosion causes soil and environmental degradation. The high cost of petroleum mulches and their destructive effects on the environment have led to the use of environmentally friendly and cheaper materials. In this study, the control of surface erosion of sand dust in the Jabalkandi region has been investigated by enhancing its surface strength by microbial-induced carbonate precipitation. An aerobic sporosarcinapasteurii bacteria, which exists pervasively in natural soil deposits was utilized to control soil erosion. The industrial corn extract has been used to cultivate this bacterium. To evaluate the effect of bacteria, the undrained shear strength of the soil was measured using insitu vane shear apparatus. The evaluated parameters included the bacteria concentration, retention time, effect of double injection with 7 days delay period, effect of environmental conditions on the bacteria functionality and the rate of gain of surface strength. The results showed improvement of the soil shear strength with time. The resulted maximum soil shear strength was 0. 65 kg/cm2. The results indicated that the reinjection of the bacteria solution and cementation resulted in 60 percent extra surface strength gain of the soil compared to one time injection.