مجله سامانه های سطوح آبگیر باران
سال سوم شماره 3 (پیاپی 8، پاییز 1394)

Water shortage in arid and semi-arid world results in fragile environmental conditions. Therefore, the implementation of rainwater harvesting system is an important step in order to maximize water availability for agriculture and other uses. However, choosing the appropriate location for implementation of various systems to collect rainwater on a large scale is being a great challenge due to the need for environmental data and infrastructure. In this study, the most influential factors affecting the rainwater storage in the soil profile and runoff production in the Rudsarab watershed were fed into the analytic hierarchy process (AHP). The weights for six criteria, i.e. land use, slope, permeability, soil texture, soil depth and rainfall using ext-AHP application within the Arc GIS9.3 environment were determined as 0.4281, 0.1930, 0.0724, 0.0725, 0.0414, 0.1924, respectively for the objective of runoff production. However, based on the objective of runoff storage, the weights for criteria land use, slope, permeability, soil texture and soil depth were respectively determined as 0.102, 0.0458, 0.102, 0.504, 0.0245. Thus, in terms of runoff storage, the effect of soil texture and based on the aim of runoff production the effect of land use was more than the others for site selection in the study area. Then rain water harvesting potential map for both objectives, i.e. runoff storage and runoff production was extracted using a weighted linear combination in the GIS environment. The extracted map was classified into five suitability groups, i.e. very good, good, average, poor and very poor using the natural breaks approach. In general, it can be revealed that about 58% and 19% of the watershed area had very good and good potential for rainwater harvesting, in terms of the objectives runoff storage and runoff production, respectively. This established a more significant potential of the watershed for runoff storage, as compared with runoff production (efficiency).

The quantity of freshwater available per person in the world has been and continues to decrease due to a combination of factors, including population increase, water pollution, inadequate planning and management of transboundary and other shared waters, and inefficient operation of water supply and distribution systems. Consequently, there is an increasing potential for water scarcity, crisis and associated conflicts around the world in the future, especially in developing regions, if the current trend in water consumption and management practices continues. Climate change as a serious environmental, economic-social, psychological and political concern is also considered globally. In this fast-changing and highly-interconnected world, the problems related to water crisis and conflicts are numerous, complicated and challenging. Efforts to effectively resolve these problems require a clear vision of the future water availability and demand as well as new ways of thinking, developing and implementing water planning and management practices. First, comprehensive observations and evidences for the potential of available water, amount of consuming water separated by continents and also assessment of past, present and future of the world's water situation is investigated and for some applied strategies and guidelines are suggested as an integrated framework for adaption to climate change.

Always, one of the expert subjects has been being the low irrigation efficiency and water utilization in agriculture for the surface flows. To investigate this issue, basin of Dasht-Sefidrud which only use the surface water, was selected as the study pattern. Then, based on the region's major product, it was sampled the transmission efficiency, water use efficiency and water utility in the field. Results showed that the transmission efficiency in irrigation networks with concrete cover was between 75 to 92 percent whereas, if the canal has been terrestrial and long, the irrigation efficiency would have reduced to 37/7 percent. Water use efficiency in farms under pressure of drip and sprinkler irrigations is more than 90 percent, but if the system is not be managed well, the efficiency will be reduced and reached to 63 percent. Water use efficiency in gravity irrigation is very variable, so that rice fields in which irrigation is as water flooding, the irrigation efficiency will come to 57 to 76 percent, respectively. If the management and plot size and dimensions are not appropriated, the irrigation efficiency will be greatly reduced and reached to 29 percent. Irrigation efficiency is obtained by multiplying the transmission efficiency in application efficiency. The minimum measured efficiency has been 14.2 percent and its maximum in pressure irrigation system was 95/1 percent, that the average of those will be about 57/7 percent. High level of irrigation efficiency caused the farmers recognize the importance of water and water management in recent years, and increase the irrigation efficiency in their farms and gardens.

Rainfall Trend in Iran indicates that the country goes to the drought and planning and management of water resources should be based on this condition. Dry areas have agricultural potential that couldn’t be used completely but using the specific methods they would be suitable for the best use. The main aim of this study was to evaluate the Tasouj aquifer flood management located in the Urmia lake basin. To do this study, meteorological and hydrometric data were collected and then organized using Excel and SPSS for future process. Based on the results, according to the monthly discharge and water requirements, it seems that acreage of under crop lands in comparison to basin yield is low and it’s possible, with a programmed water storage in non-crop season, to be compensated, to some extent, water requirements of the region. During the 14-year performance of watershed management, about 2 million cubic meters and on average of 159759.6 cubic meters of flood water, about 13 percent of average precipitation in the 14-year period of monitoring, passing through the passageway as depth infiltration, was extracted and injected into aquifer table per year. In the seasons, spring, with 80 percent and summer about 2 percent, showed the highest and lowest performance in terms of stored flood.

In this study, trends in the monthly, seasonal and annual river discharge and rainfall by use of nonparametric test such as Kendall, Mann-Kendall, sen,spearman and pearson parametric correlation in Dargaz Daroongar basin were studied. For this purpose, discharge data from hydrometric stations Mohammad Taqi Beyk,sang surakh and Golkhandan and precipitation data from Dargaz, Mohammad Taqi Beyk, sang surakh and shamkhal stations were used. The results showed that the seasonal and annual trends were decrised in stations Mohammad Taqi Beyk and golkhandan. Pearson parametric and non-parametric Spearman were used to illustrate the relation between rainfall and river flows in a region and a significant positive correlation between summer rainfall and river flows have been approved by both tests

Water shortage has led to a fragile living condition in arid and semi-arid regions of the globe. Due to the limited time and amount of rainfall in these areas, presenting solutions for the utilization of rain water is the main concern of many residents and managers of these areas. There are some criteria to select the appropriate method of water harvesting and also site selection according to environmental conditions. In this study, to site selection of the projects Pitting, Furrowing, and Terracing, several types of spatial data, i.e. plant cover, soil, topography and climate were overlaid within a GIS framework through the Analytic Hierarchy Process (AHP) in a three step approach. In the first step, the hierarchical level was formed using the objectives, criteria and sub-criteria. During the second step, pair wise comparisons were implemented and consistency ratio was computed. Inconsistency ratio of the judgments for the projects Furrowing, Pitting and Terracing were determined to be 0.07, 0.03, and 0.04, respectively. These ratios were lower than the standard level of 0.1. Therefore the calculated weights were desired to be validated. Results showed that the criteria topography and climate with a normal weight of 0.563 and 0.055 respectively had the highest and the lowest impact on the site selection of Pitting. The same situation was happened for the projects Furrowing and Terracing with the normal weights 0.563, 0.055 and 0.566, 0.081, respectively. In the third step, all layers were overlaid to extract the suitability maps of the defined projects. Validation analysis of the suitability maps revealed that the suitability map of the Pitting project with the accuracy level of 79% was in the highest level of accuracy among the extracted suitability maps.

Notes to investigate and identify problems in the implementation of research projects the effect of water spreading on water resources, the importance of methods, performance and results of research carried out previously necessary. Looking for station research, education and extension Floodwater spreading in the country, Monitoring and monitoring of various factors, including the monitoring of water resources is also on the agenda. In this paper, we investigate various sources of internal and external quantitative and qualitative parameters of water resources evaluated and is considered to reach the target. Investigation records show that during the past years in various parts of the country related research projects have been implemented or are under implementation. The results of this study indicate that the static level rise and increases in most stations control the water level in piezometer wells and aqueducts that our agriculture and increasing the flow. Plan spreading in many parts of the country and alleviate the effects of drought and sometimes neutralize it.