فصلنامه حفاظت منابع آب و خاک
سال نهم شماره 4 (پیاپی 36، تابستان 1399)

Inappropriate distribution of precipitation measurement stations has increased the use of gridded precipitation datasets consisting of satellite, reanalysis and ground- based datasets .Accurate measurement and estimation of precipitation amounts and events is very important. With the increasing development of satellite technologies in recent decades, access to high spatio- temporal resolution of precipitation data has been provided in many parts of the world. Given that these precipitation datasets cannot be used without initial assessment due to uncertainties in estimating cloud and precipitation thickness. The purpose of this study was to evaluate CMORPH, PERSIANN and PERSIANN-CDR precipitation datasets based on statistical indices such as contingency table indices at Dare-roud basin which is located in Ardabil province. Results show that CMORPH product performs better in estimating basin precipitation in most of the stations with RMSE index less than 3 mm and CC index higher than 0.7. Also in terms of the contingency table indices, the CMORPH performs better in most of the indices (except Bias) than other products, so it is recommended to correct its bias and use this precipitation product in future studies in Darehroud basin.

Preserving theenvironment and making fossil fuels viable for energy production,as well as power grid losses and low efficiency of thermal power plants,have drawn human attention to the use of alternative and renewable resources of energy such as hydro energy.One of the most effective approaches to operational management of the urban water supply networks is to control the surplus hydraulic pressure in some parts of the system.Therefore,utilizing the potential head along main gravity pipelines route to recover energy can be considered as a favourable strategy for optimum flow control and managementof the water pressure in the network.In this study,by applying hydraulic simulation of a given water supply network,the important hydraulic parameters such as available net pressure head in various locations of water pipeline and water reservoirs inflow have been derived Hence,by considering these essentialparameters and taking into account the topographicstatus of water transmission route and hydraulic grade line elevation at each point,the power output was calculated at nine selected hydropower sites.In addition,to Prioritizing the construction and operation of the proposed hydropower potentials and providing useful guidanceto authorities,investors and executive managers,a multi-criteria decision-making analysis based on the analytic hierarchy process was conducted according to five key criteria including technical,economic,social,passive defence and environmental aspects.Hence,a comprehensive multi-criteria model based on AHP and questionnaires has been developed to rank hydro energy production in proposed sites in a water supply network.By analysing the expert questionnaires and weighting to each of the criteria and sub-criteria (pairwise comparison) inthe Expert Choice software,it was found that thetechnical,economic,environmental,passive defence and social criteria were ranked in firstto fifth place, respectively.The results showed that micro hydropower potential sites in R.1183, R.1453 and R.57reservoirs with installed capacity of 3100, 4107 and 1072 KW respectively,were ranked in the first to third priority of construction in the studied water supply network.

The high share of agricultural water consumption compared to other sectors and the serious crisis of dehydration in recent years reform and offer optimal crop pattern that reduces water consumption and increases the efficiency of its use, the requirements of most forbiddens and critical plains of the country. The purpose of this study was to provide optimal cropping pattern in relation to Allocable Water agriculture communicated by the Ministry of Energy and the long-term cumulative accumulation deficit of aquifers and the emphasis on agricultural sustainability indicators in the twenty-year planning horizon, Qom-Kahak study area. To simulate rainfall component behavior, outcomes of A2 scenario for the HADCM3 climatic model were used and using the continuity equation balance,the volume of water allocated to the crop sector was estimated each year. Then, using fuzzy utopian planning models, sustainable agriculture patterns were presented within the framework of technical constraints. The results showed that the implementation of the proposed agronomic models will in addition to offset the deficit of 536 million cubic meters and aquifer balance in the study area over the planning horizon, It will increase labor force and physical productivity of water, fertilizers and pesticides consumption will increase by 10.7%, 106%, 4.1% and 8.8% respectively, and water resources, fertilizers and chemicals consumption will reduce by 48.2%, 3.9%, 8 respectively.. Therefore, it is suggested to regional authorities to prioritize the implementation of proposed agro-projects, which requires the development of legal requirements, incentive and punitive policies, and conducting training and extension courses.

This study was conducted to evaluate the CWSI index in different cultivars of maize under drip irrigation Strategies at Safi Abad Agricultural Research Center, north of Khuzestan province. Irrigation management factors included T100 (100% water requirement), T75 (75% water requirement) and T50 (50% water requirement) were in main plots and maize hybrids including Single Cross 704 (SC), Mobin (M) and Karun (K) were subplots. High and low baseline relationships were estimated for all three cultivars with high accuracy (R2 <0.8) during the growing season. CWSI index varied from 0.01 to 0.46 for different treatments and at different growth stages. The results of statistical analysis showed that the difference of water stress index of maize was not significant between different cultivars but the effect of irrigation management on it was significant at 1% probability level. Accordingly, CWSI values of 0.17, 0.15, and 0.12 were estimated for corn growth and development, middle and end stages, respectively, to determine drip irrigation time using this index. In addition, the results showed that there was a high correlation between CWSI and maize yield and were derived the relationships to estimate yield by using this index. Based on these relationships, Caron hybrid had the highest sensitivityto water stress, with the coefficient or slope of grain and biological yield reduction against water stress were 21% and 47% respectively than were higher from other two cultivars.

Assessment of land use capabilities based on regional conditions is essential to reduce human impacts on natural resources and to identify suitable land uses. However, the selection of appropriate method for evaluating the potential of the land at the watershed scale has received less attention. Therefore, the present study aimed to apply and validate three methods of FAO, USDA and the Forests, Range and Watershed Management Organization (FRWMO) in assessing the land capability of the Oshnavieh Galazchai Watershed in West Azerbaijan, Iran. Towards this, different criteria were assessed for designation of land capability for the Galazchai Watershed based on the available standards. Corresponding available data were consequently obtained using 122 soil samples taken throughout the watershed as well as topographic and meteorological information. According to the results of the study, the highest and the lowest absolute changes were regarded to the FRWMO and FAO methods with an area of 6682 and 5656 ha, respectively. On the other hand, the maximum disagreement was found between the current land use with the FRWMO method with Kappa of 0.64, which is due to allocation of land with steep slope to agriculture and orchard. Hence, it is recommended to allocate land to different uses according to the land potential of the region and also considering the economic and social conditions of watershed stakeholders after applying land use changes to maximize the satisfaction of all stakeholders and lead to sustainability of the study watershed.

One of the main pillars of sustainable agriculture is the use of biofertilizers in agro-ecosystems to modify and reduce the use of chemical inputs. This study was carried out to investigate the effect of growth promoting bacteria on soil chemical properties in a clover- rice cropping system using a factorial experiment with randomized complete blocks having three replications at the research site of Rice Research Institute of Iran, during 2015- 17. Experimental factors for clover included four levels of inoculation with symbiotic bacteria Rhizobium trifolii and four levels of inoculation with non- symbiotic plant growth promoting bacteria. The results showed that clover cultivation led to a significant increase in the percentage of soil organic carbon (1.79%) and nitrogen (0.216%). The Application of non-symbiotic bacteria in clover cultivation caused a significant increase in soil phosphorus in rice cultivation. The highest amount of soil phosphorus was obtained in treatments of Pseudomonas (12.38%) and Azotobacter+ Pseudomonas (11.8 ppm) in rice cultivation. Also, rice cultivation significant reduced available potassium in the second year (121.1 mg/kg) compared to the first year (128.3 mg/kg). According to the overall results of this study, the use of growth promoting bacteria while maintaining and improving the chemical properties of the soil increased the average rice yield in the second year (3250.3 kg/ha).

This study was conducted in order to digital mapping soil classes according to WRB system was conducted by boosted regression tree (BRT) method on about 60.000 hectares of Hirmand county lands. 108 soil profiles were dug and soil profiles were sampled and described based on WRB system. Twenty environmental covariates were used as estimators for soil mapping including terrain attributes and remote sensing covariates. Results showed that the young soil covered the study area and mostly influenced by flood sediment which classified as Fluvisol and Cambisol groups and Solonchak group in salt -affected area. The variable importance showed that the environmental attributes such as Multi-resolution Valley Bottom Flatness Index (MrVBF), Valley Depth, Convergence Index, Catchment Area and Salinity Index (NDSI) had the highest importance among all covariates for two levels of WRB prediction. The validation results showed that the BRT model could predict WRB1 and WRB2 levels with overall accuracy of 47 and 25%, respectively, and also from WRB1 to WRB2 levels the accuracy decreased. In low relief area and young soil that the low soils variability, digital soil mapping approach could be useful, efficient, and fast technique to produce and predict soil classes map.

In this research, which was carried out in the 4.5-ha consolidated paddy fields of Sari Agricultural Sciences and Natural Resources University during two cropping cycles of 2015-2016 and 2016-2017, the influence of different drainage systems on total nitrate loss into local surface water resources was investigated. These systems included three regular subsurface drainage systems with different drain depths and spacings of, respectively, 0.9 m and 30 m (D0.90L30), 0.65 m and 30 m (D0.65L30), and 0.65 m and 15 m (D0.65L15), and a bilevel drainage system consisting of four drain lines with 15 m spacing and 0.65 and 0.9 m alternative depth (Bilevel). In addition to daily measuring drainage fluxes, nitrate concentrations in the collected drainage water were also measured every other weeks during the cropping cycles. Daily average drainage discharges under Bilevel, D0.90L30, D0.65L30, and D0.65L15 varied in the ranges of 0-231 cm3 s-1, 0-220 cm3 s-1, 0-227 cm3 s-1 and 0-250 cm3 s-1, respectively. Analyzing precipitation-drainage discharge correlations reveals that the precipitation intensity of 10 mm d-1 is the threshold of drainage capacity reduction, and precipitation intensities beyond this threshold may result in water logging challenges in the study area. Consolidating the selected drainage systems may result in annual nitrate losses of 2.2-34.7 kg ha-1 into the surface water resources; however, the D0.65L30 systems may have less environmental consequences in this view of point. Therefore, environmentally sustainable operations of these systems for expanding rainfed-cropping requires precious investigations when selecting drain depths and spacings.

Streamflow Drought Index (SDI) is based on the assumption that the flow data series follows from Gamma distribution. In this study, the efficiency of 65 statistical distributions was evaluated through the use of monthly and annual flow data series of 49 hydrometric stations. The results show that on the annual scale, Gamma distribution is not the superior distribution. On a monthly scale, this distribution was found only in 1% of all cases examined as the superior distribution. This is while the Wakeby distribution was introduced on an annual basis in about 35 percent of the cases, and on a monthly scale, up to 43 percent of the scenarios were introduced as a top-ranked distribution. Based on the SDI index calculated based on Gamma distribution and Wakeby distribution, in the case of the P-Value of the Gamma distribution is less than 0.3, it is possible to move the drought classes using Wakeby distribution. These conditions were observed in 30% of the examined cases. The highest and the lowest displacements of the hydrological drought classes due to the use of superior distribution were in December and May, respectively. It was found that the highest frequency of displacement of the drought classes resulted from the use of superior distribution occurs in the normal class. Accordingly, it is recommended that the Wakeby distribution be replaced by the gamma distribution in the SDI calculations.