مجله سامانه های سطوح آبگیر باران
سال ششم شماره 4 (پیاپی 19، پاییز و زمستان 1397)

In this study, for climate zoning and determining the effects of climate change on discharge of Jajrood River Basin, data from 9 available stations in Jajrood River Basin were used. In order to create climatic zones in the Jajrood River Basin, multivariate cluster analysis was used. To validate the data, discriminant analysis was employed. For investigating the effects of temperature and precipitation on discharge of Jajrood River, spatial distribution of discharge, temperature and precipitation parameters were used. According to cluster analysis of the area under study, the basin includes a wet and temperate zone, a dry and temperate zone, a dry and warm zone, and a wet and cold zone. Results of the spatial analysis of climate parameters showed the significant relationship between discharge variations and precipitation, in relation to the other parameters. The spatial distribution of the coefficient of correlation between temperature and discharge indicates that there is low correlation between discharge and temperature. Even in areas where a significant relationship is observed, it is negligible. Generally, it can be said that the fluctuations of the Jajrood Basin are more affected by precipitation than temperature.

Today, attention to indigenous knowledge in the field of water and soil has great importance due to its special functions, high compatibility, and ability to maintain ecological balance and promote popular participation. Since the ancient times, people of Hormozgan province have used different ways of utilizing water and soil resources and harvesting rainwater, due to the climate limitation that exist in this area. One of the most prominent examples are the Darband and Kashband structures in the eastern parts of Hormozgan province. Today, these structures are referred to as household economic units in the Bashagard region of Hormozgan. Darband and Kashband are indigenous structures of watershed management in Hormozgan province. These types of structures are made in mountainous areas by natives of the region to create a cultivation area. In the local legal system, the streams and green valleys created by Darband and Kashband have a certain owner. Darbands are constructed as short transverse check dams perpendicular to the flow of water, with a height of approximately 1 to 1.5 meters. Increasing the height of these structures is possible after sedimentation and planting in the following years. The result of Kashband construction is the creation of new lands and suitable cultivation beds on the margins of rivers, along with maintaining soil moisture. This method increases soil moisture and plant growth. Mostly, Darbands and Kashbands are made with rocky materials without cement. However, Darbands with a height of 2.5 to 3 meters are made with rock and cement. The most important agricultural products that are cultivated behind these structures are palm, garlic and citrus. Most of these structures exist in Bashagard region and also parts of the Minab region. Bashagard region includes basins of Jagin and Gabrik reservoir dams. According to available information, more than 4,000 structures (Darband and Kashband) were constructed in the Bashagard district. The results of this study show that this kind of indigenous knowledge has a very long history in the Bashagard area. Therefore, utilizing the economic capacity of the streams with the participation of the people can be very important as a native model in soil and water conservation and as a source of jobs for watershed residents.

The Standardized Precipitation Index (SPI) is the most common index for drought monitoring. Although the calculation of this index is usually done by using the gamma distribution fitting of precipitation data, studies have shown that for accurate monitoring of drought, the optimal distribution of precipitation in each month should be determined. On the other hand, in non-stationary time series, it is not possible to determine the proper parameters of probability distributions. Hence, in recent years, the non-parametric SPI has been introduced, in which the parametric distribution is replaced by an empirical probability distribution. However, in national studies, there is still insufficient attention to non-parametric drought indicators. Therefore, in this paper, the performance of the nonparametric SPI was evaluated for drought monitoring over Gorganroud basin during 1972 to 2015 and the results were compared with the parametric SPI. The SDAT software package was also introduced to calculate nonparametric drought indices. The results of this study showed that time series of the parametric approach based on the best probability distributions and the nonparametric approach are well correlated with each other. The correlation coefficient between the two-time series is equal to one. Drought events have been detected at the same time based on the two approaches. Based on the SPI12 in both parametric and non-parametric approaches, the longest drought occurred in the basin between February 1983 and March 1984 for a period of 14 months, during this period, the basin suffered severe drought.

Due to the lack of adequate sources of drinking water and uncertainty about the quality of these sources, along with rising water demand due to population growth, it is important to find a suitable solution to supply drinking water. Rainwater harvesting from roofs and use of natural discharge from springs are among techniques which can replace surface and underground water resources. The city of Divandareh in Kurdistan province has a strong potential to utilize these two sources. According to population statistics from 2011, the annual water consumption per capita of the city is 1871110 cubic meters. Our results showed that these two sources can provide 1001235 cubic meters of water per year. Based on the average annual consumption of each person in the city, springs and harvested rain can meet  53.5% of the city’s water demand, priced at 5,256,483,960 rials per year using the price of drinking water, and 4,246,463,320 rials per year using the price of raw water. The results indicated that in the case of comprehensive management of these two resources for optimal storage and utilization, they could be suitable options to compensate for abnormal water consumption, and in some cases the conditions of permanent stress and water shortage in the city would be prevented.

In recent decades, extensive research has been carried out to collect and store rain and runoff around the world. In addition to applying different water harvesting methods, and reducing the risk of runoff, other measures such as increasing soil moisture content and cultivation of tree and rangeland species have been studied. There are many water-related environmental problems which, according to researchers, are partly due to the use of new technologies. Part of the body of research focuses on the importance of the indigenous knowledge of water harvesting techniques, and even its integration with new knowledge as a means of sustainable development in this sector. Identifying these traditional methods, which are usually local and consistent with the ecosystem of the region, is the first step towards using them. Since ancient times, different methods have been used for collecting runoff and rainwater in different parts of Iran, in accordance with different climates of Iran. In this paper, one of the native methods of collecting rainwater, known as Perch, used in the past in the mountainous regions of Kohgiluyeh and Boyerahmad province is introduced for the first time.

Today, increase in flood frequency and intensity, and flash flood events have caused environmental issues and increased human and economic losses. As a result, numerous tools and new programs for flood forecasting systems and risk management programs are being used in the relevant period. There are models that make it easy to be used for this purpose. In this research, MISDc model was applied to investigate the runoff of Kashkan Afrine basin in Lorestan province. MISDc is one of the semi-distributed rainfall runoff models that is implemented to estimate floods. In order to simulate daily river flow using the MISDc model, daily rainfall, temperature and flow data of the basin, for a 12 year period (2004-2015) were used. In the calibration period (first 9 years), by calibrating 9 parameters of the model, the optimum values of river flow were obtained, and were used in the validation period (the last 3 years data). In order to evaluate the simulation accuracy of the model, Nash-Sutcliff (NS) and R2 criterea were used. According to the results, simulation accuracy based on evaluation criteria values (NS and R2) were 0.68 and 0.56 for the calibration period (2004-2012) and 0.74 and 0.57 for the validation period (2013-2015), rspectively. These results indicate the ability of the model to simulate the runoff of the basin. Moreover, the results of observed and simulated hydrographs comparison show that the model can well simulate the flow of the studied basin, especially peak peaks.

In this study, the effects of three land use categories on runoff quality was investigated using a rainfall simulator, in six sub-catchments in Kakasharaf watershed in Lorestan province. In total, 39 instances of artificial rain with a duration 30 min were created and the amount of phosphorus and potassium in the resulting runoff was measured on three land uses. The results showed that the average amount of phosphorus in runoff in forest, pasture and agriculture  land uses was respectively 0.22, 0.26 and 0.21 mg/kg. Also, the amount of potassium in runoff of forest, pasture and agriculture was respectively 18.38, 22.32 and 18.71mg/kg. Analysis of variance for the effect of land use on removal of phosphorus and potassium showed that the results were not statistically significant for phosphorous on slopes with 10% and 20% inclination and for potassium on a slope of 30% inclination. However, the effects of land use on the amount of potassium in runoff on slopes with 10% inclination was significant at the 95% confidence level.  On slopes with 20% inclination, the effect was significant at 99% confidence level.