مجله ترویج و توسعه آبخیزداری
پیاپی 36 (بهار 1401)

One of the important problems of water resources studies is estimating the spatial distribution of rainfall based on point rainfall observations. In the present study, interpolation methods including definitive mathematical methods including Inverse Distance Weighting(IDW)  and Radial Basis Functions (RBF), Global polynomials, and local polynomials, and Kriging and Cokriging geostatistical methods using Geographic Information System (GIS) to estimate monthly and annual rainfall in the Namak lake watershed were evaluated. Spatial distribution analysis was carried out in the period 1988-1999 to 2006-2007 water year. In this study, in order to compare interpolation methods in iso-rainfall of the Namak lake watershed, 110 meteorological stations into the mentioned watershed with the statistical period of 30 years were used. The results showed that overall in annual rainfall according to Root Mean Square (RMSE) index, Cokriging and Kriging geostatistical methods in rank one and two, respectively have the best rainfall estimation. Therefore, Cokriging method with RMSE of 63.68mm had the best estimation. RBF, Cokriging and Kriging methods had also in the best estimation for   monthly rainfall data. In general, geostatistical methods have been overestimated in monthly and annual rainfall estimation in the Namak lake watershed.

Water scarcity‎ in the world has become a serious crisis, of which the importance has been shown in arid and semi-arid regions. Solutions to confronting with the water crisis are summarized in two strategies of water resources management and extraction of new water resources. In Iran, water resources management has a high priority due to geographical and climatic conditions. Rainwater harvesting from precipitation is one of the measures in which success leads to increased water storage and a reduction in the drought crisis. If locating underground dam construction is conducted properly as well as constructing in a convenient location; so, it can be a suitable proxy for water needs. Therefore, in this study, underground dam has been introduced as a new technique for rainwater extraction, besides the conditions for construction and location of these dams. Finally, the factors were classified into three groups including physiographic factor, hydrological factor and socio-economic factor.

Information resources and communication channels, can Informing and notifying role, as an agent of change in knowledge, perception and attitude, the most important role to play in preventing the degradation of natural resources. The aim of this study was the role of pastoralists resources and communication channels in attitude towards the reform and rehabilitation of rangelands in the Qorveh city (Kurdistan), respectively. The population of 400 people were pastoralists who are using Morgan table, 196 individuals were selected in this study. For data evaluation SPSS version software was used 22. The data collected in this study was by a questionnaire. Was used to determine the validity of a panel of experts. In order to estimate the reliability of the test Cronbach's alpha coefficient was used. To assess the relationship between independent variables (national channels, local channels and international channels) of Spearman's rank correlation coefficient was used. Also, to assess the relationship between independent variables and the dependent variable of the statements of each of Kendall's tau b rank correlation coefficient was used. The results showed that the national channels, local and international pastoralists attitude positive and significant relationship. Also, the findings demonstrate that local variable with the most channels and international channels with the lowest relative importance of the independent variables. In addition, results showed that the results of the study showed that the index of communication channels and information sources to account for 56% of the total variance of attitude towards the reform and rehabilitation of rangelands were pastoralists.

Drought is one of the main natural causes in agricultural, economic and environmental sections. It is very difficult to quantify the characteristics of the severity, magnitude and duration of the drought objectively. Therefore, much effort has been made to monitor drought using a variety of indices. In order to investigate the meteorological drought on hydrological systems in the study area, were used from Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI), SRI Standardized Runoff Index (SRI) and groundwater drought index (GRI). Then, the relationship between the indices, concurrence or non-concurrence of drought event was investigated. Finally, the best meteorological drought index for monitoring hydrological systems in the study region was selected. The results showed that comparing the correlation between the two meteorological indicators with SRI and GRI, SPEI is a priority in terms of drought warning, because it is able to show the occurrence of hydrological drought on a shorter time scale. There was no significant correlation at different time scales between the two SPI-GRI indices (cc = 0.18), which indicates the inadequacy of SPI to investigate the effects of climatic drought on groundwater level. Therefore, it is suggested to use SPEI instead of SPI to investigate the effect of precipitation changes on groundwater fluctuations.

Active tectonics in the basins causes the formation of various phenomena such as alluvial fans, terraces, faults and causes various changes in the morphometry of basins. The aim of the present study was to identify the morphological features of Sharghonj watershed in Birjand. Basin shape coefficient, shape ratio, compaction coefficient, canal surface density index, branching, hypsometric integral, unevenness ratio, unevenness coefficient, land slope, relative prominence, meandering intermediate degree and longitudinal river gradient have been used. The results showed that according to the Horton ordering, the highest stream order of the watershed is six. The basin shape coefficient, basin shape ratio and basin compaction coefficient or gravelius were 0.2, 2.4 and 2.02, respectively. Also, hypsometric integral indices, ratio and roughness coefficient, ground slope by degree and relative prominence were calculated as 0.5, 0.62, 609, 25 and 428, respectively. These indicators showed that the basin is elongated in shape and has young elevations. In terms of neotectonic activities in the region, the LAT index for the basin is 4.25 and the basin is placed in group 4 of this division and has a low intensity of neotectonic activity.

Access to fresh and quality water is one of the most important issues for humans today. Having healthy water resources is an essential prerequisite for maintaining environmental quality and economic, political, social and cultural development. Increasing population and urban, agricultural and industrial development of the country further highlights the importance of paying attention to the quality of available water resources. With increasing of demand for water supplies and continued pollution of rivers and other waters, this will become a growing crisis in the future. Surface waters or rivers are the most important water resources that play an important role in supplying the water needed for various activities such as agriculture, industry, drinking and power generation. Today, using a simulation model is a common approach to water quality monitoring along the river's path. In this research, the water quality of Tajan River in Mazandaran province was evaluated, which is considered as one of the most important sources of water supply in different parts of the province. Using qualitative numerical simulation model (Qual2kw), investigated the process of changing the parameters of water quality parameters such as dissolved oxygen (DO), biological oxygenation (BOD), acidity (pH), electrical conductivity (EC), nitrate (NO3-) and phosphate (PO43-). The average monthly data from 1385 to 1395 was entered into the model at three stations of the water regional company and environmental office along the river. Calibration of the model was performed based on the low water season data (September) and validation of the model was based on the high season data (December and February). The results of the Tajan River simulation showed that the Qual2kw model provides an appropriate estimation of the river quality conditions and this model could simulate the parameters with the appropriate accuracy. The results showed that despite the presence of point and non-point pollutant sources along the Tajan River, there is no limiting factor in supplying drinking water and agriculture at the downstream. In the aspect of agriculture, the water quality is suitable for agriculture in the whole of the river path. Only Kordkhil station was good category due to located in the downstream of the river and the rest of the stations are in the excellent category, which can be used for agriculture. The maximum self-purification power was belonging to the interval 2 (between Pol-e-Tajan and Kordkhil) equal to 7485.346 tons per day and the minimum of self-purification power was belonging to the interval (1) (between Rig-Cheshmeh and the Pol-e-Tajan) equal to 102.6805 tons per day. This trend shows that the power of self-purification of the river was increased from upstream to downstream.

Today, water resources have become one of the major concerns in arid and semi-arid regions of the world. Low rainfall and its irregular distribution in Iran, along with rapid population growth and increased agricultural activities, have caused recent droughts. The present study was conducted with the aim of investigating and forecasting meteorological drought in Tehran province using the ARIMA model. Data from seven rainfall stations for the period 2000-2020 were used to evaluate the Standardized Precipitation Index (SPI). Then, the ARIMA model for drought prediction was implemented based on SPI, and the best model for drought prediction was extracted for each station. The results showed that ARIMA time series models can correctly evaluate climate change. Also, according to the results of the SPI drought index for the forecasted period, it was found that the situation was close to normal in all the studied stations, and from 2022 to 2024, the conditions have progressed towards improving the rainfall situation, which according to the recent rainfall in Iran, this model It has been able to model climate changes well. According to the SPI index, the drought in the target area is close to normal, it can be a suitable tool for managing water resources, preserving natural ecosystems, and improving the future climate.