مجله سامانه های سطوح آبگیر باران
سال سوم شماره 4 (پیاپی 9، زمستان 1394)

The first step in water resources modeling of a zone is assessment of climate situation on past and future duration. A hydrological modeling with consideration of the latest and most complete production tools evaluate variation of these parameters. Precipitation as the first provisioning of water source has always been of interest. Thus, its variation will be important. Since southern khorasan has not a high capability for attaining surface water resources; therefore, spatial attention to variations of this parameter has a high importance. In this study precipitation was extracted from the outputs of AOGCM model (HADCM3) under A1B scenario and the consequences of climate change in the next 30 years were assessed. The amount of annual precipitation in 3 decades, i.e. 2020, 2030 and 2040 were examined. Finally, zoning of changes in precipitation pattern was carried out. The results showed that there will be a significant downward trend in rainfall. Furthermore, in third decade, Asadiyeh will be in the best situation in terms of precipitation amount while Nahbandan and Tabas will have the worst situation.

Aim of this research was to evaluate the efficiency of traditnal terraces and its impact on some of the characteristics of the soil in Hamun watershed.. To carry out this study, beside the assessment of volume and method of construction, samples of soil were collected from inside and outside of this research area. Then, we analyzed some factors such as pH, Ec, ... all of data analyzed by SPSS software. Assessment of structures sustainability has shown that terraces have been built according to scientific principles. The results of statistical analyses have indicated no significant changes on silt percentage. While, the amount of pH, EC, sedium, clay, calcium, … in terrace structure as statistically significant at the 0.01 level So, terraces have been created suitable micro-climate and causes improve of soil quality especially reduced salinity in this dry land area.

Planning and management of water resources in arid regions are recognized as two important issues. The purpose of this research is to study the potential of water resources in the basin Meshnaq Chay. To do this study, meteorological and hydrometric data from the study area were collected and organized for subsequent processing. To locate and determine the appropriate location of the dam axis, 40 geophysical probe, and 7 piezometric well was implemented. Basin water balance based on meteorological, hydrometric and land use data was estimated. Then, using Geoelectrics and Piezometric information, the volume of water that can be stored in the proposed location of underground dams along with Regulatory volume of reservoir were calculated. The results showed that in case of rain as 330.2 mm, drought climatic conditions of the area would be within the normal range. Excess water in the non-cultivated season was estimated about 305,683 cubic meters that can be stored by groundwater dam. Annually Storage capacity of aquifers would be more than 100,000 cubic meters of reservoir regulation volume if farmers simultaneously make use of stored water, which due to water shortage in the Meshnaq village, the lack of the required water volume of the village lands can be compensated.

Increasing greenhouse gases on earth especially after the Industrial Revolution that led to sensible changes by human’s activities is called climate change. Assessment of the effects of the climate change on different parts of the water cycle for the better managing is very important. In this research, the hydrological model has been studied to assess the effects of climate change on water resources in Beheshtabad catchment. The effects of climate change are investigated in future periods. In this study, SWAT-2009 model has been used to simulate the watershed and it has calculated the amount of runoff. The results of simulation (in daily step) and existing hydrometric data have been used for calibration and validation by SUFI-2 algorithm and the 15-year period (2013-1998). The output of hydrometric stations have been used, the output of general circulation models, and LARS-WG model (HadCM3) in order to assess the effect of climate change on runoff under the climate scenarios A1B, A2 and A1B for the period (2020s), (2050s) and (2080s). The results of climate simulations have been introduced to SWAT model in change factors method. Then by re-running the model for the three above scenarios. The results showed that the annual mean temperature has been increased in the coming period in all scenarios except of B1 and runoff scenarios for the near and distant future generations get dropped. So that under the most difficult conditions the amount of runoff of Beheshtabad catchment will be decreased by 45 percent until 2100 and for the A2 scenario.

Recently in Iran, with regard to the rising trend of population growth rate and water demand, the volume of groundwater and surface water resources have faced with significant reduction. One of the ways to prevent from reduction of resources and to protect them is the management of water consumption especially in the urban sector. This study aimed to control the Birjand water consumption using systems thinking and the Vensim software. In this model at first, available per capita during 2008 to 2013 was simulated and then was proceeded to predict urban water per capita by 2042. Then per capita obtained based on the definition of consumption control policy that consider the parameters leakage reduction, increased use of components of consumption reducer in the household sector and public in the city, reduced bath time, increased price of water, reduction of the holidays and separation of water supply network of green spaces from the urban water supply network. The simulation results was compared with the existing per capita in Birjand. The results indicated that with control consumption, urban water per capita was decreased by 29.11% as compared with the usual conditions of the region. It consequently caused a reduction of the volume of water abstracted from groundwater resources due to reducing the volume of water entering the municipal sector.

Water crisis in Iran justify the implementation of different water extraction projects. Kashmar flood spreading project has been so costly like other flood spreading projects. Economic evaluation of these activities to determine benefit-cost ratio is essential, because of different views about the results and efficiency of flood spreading projects. Firstly, all costs and incomes of Kashmar flood spreading were determined for given years. Then the economic efficiency of the project was assessed by using the common engineering economic methods. Economic evaluation of this project indicated that the profitability was higher than the cost of implementing it by considering 20% profit, the net present values (NPV) of it is 243944716.8 Rials which is positive yet. The Benefit- cost ratio (B/C) is 1/74 which showed that the project is economic. Finally, internal rate of return of this project is calculated as 55% that the comparison of this amount to the acceptable minimum rate namely 20% has indicated that Kashmar flood spreading project is completely economic.

The Urmia Lake (N-E Iran) is about to be completely dried so that many precious animals species could be scattered around looking for water and food. Occasional counter measures have been undertaken by local authorities including water transformation by ship and helicopter which could not be considered to be a sustainable solution in the long term scale. One should note that apart from water scarcity, animal forage has been also affected by recent drought. Therefore, any solution proposed for providing animal drinking water, should consider a sustainable planting practices at the same time. Rainwater harvesting (RWH) is a modern solution for collecting, conducting and storing rainfall induced runoff from natural and artificial impermeable surfaces. This method is particularly useful for remote area where usual water supply systems may not be applicable. Rainwater harvesting systems is composed of a catchment, conveying devices and storage facilities. Catchment should be almost impermeable and large enough to provide required amount of water during individual or several consequent rainfall events. Catchment surface may be naturally impervious or can be artificially isolated for maximum runoff production using different material types such as cement, bitumen or PVC membranes. Runoff generated by impervious catchment can be conveyed into a downstream reservoir using a pipeline or low height ditches. Reservoir capacity should be tailored with respect to the long term average or minimum monthly rainfall using frequency analysis. The results of the study presented here shows that in three out of four important Urmia islands (i.e. Espir, Kaboodan and Ashk) there exist long slopping rock surfaces with a good distribution along the area which can be used as impervious catchment for runoff collection. It is only in the Arezoo Island that contains more gentle topography and is covered with a weathered surface layer so that artificially constructed impervious catchment may be needed. Other possibilities such as groundwater dam to be constructed along some of the main stream channels are also considered as a good alternative and more durable solution.