مجله سامانه های سطوح آبگیر باران
سال دوم شماره 2 (پیاپی 3، تابستان 1393)

Rainfall in urban areas washes off all the material accumulated on the impervious pavement surfaces and the resulting polluted runoff negatively changes the quality of the surface waters as well as groundwaters. In this research study، the quality of rainfallin the study area including one rainfall and nine runoff samples were collected from different locations in Mashhad after rain. The EC and pH parameters was determined in situ and the ionic density of Cl، SO4، Na، Mg، Ca، and HCO3 were all measured with an atomic absorption system (AAS) at the Ferdowsi University of Mashhad. The hydrochemical type of most of the runoff samples were determined based on the Piper diagram and it was shown to be calcium sulfate (W3، W4، W5، W6، W8) and calcium bicarbonate (W7، W2، W9). The hydrogeochemical differences between the rainfall and the city runoffs can be due to factors including lithology، urban soils and dusts، and sewage inflow. According to the Scholler diagram، the water quality of the runoff samples varied from good to unsuitable; and absolutely unpleasant for drinking. Moreover، all the samples were recognized to be of low salinity to very saline for irrigation use based on Wilcox diagram.

In the area of KarnaveShirinKalat، water leakage for agriculture and drinking purposes has created crisis conditions for this district. This problem has resulted in vast migration of the villagers to adjacent towns. Karnavesubterranean canals is the main source of water for agriculture and livestock. In the past، these subterranean canals had a high discharge rate and was the main source for agriculture and domestic water. However، in recent years it has a very low discharge rate. This study showed that agronomists and shepherds of the area have an annual watershortage of about 126000 cubic meters. Thus، the main objective of this study isto investigate the possibility of harvesting waterby constructing underground dams in the KarnaveShirine area. The result of technical (including geology، groundwater and engineering geology) and socio-economic studies showed that in the KarnaveShirin area there is a narrow valley that is a suitable place for constructing an underground dam. Thus، at least 95000 cubic meters of water with a high quality can be harvested in alluvial deposits for agricultural and livestock usage. In this manner، by harvesting subsurface water، the annual net total income of agronomists and shepherds in this area has increased about 850 Million Rials.

Since the rainwater is the cleanest part of water resources in nature، if the runoff is collected and used، consumers would get involved in the process ofwater resources managementin addition to saving water. Estimation of the runoff volume، particularly in urban areas، is the main parameter. Due to the lack of or inadequacy of data، often this parameter is estimated using experimental methods which have been mostly developed for other areas. Moreover، these methods would not work properlywithout proper calibration and performance evaluation. In this study، a research project has been implemented in Building No. 2 of the Khorasan Agricultural and Natural Resources Research Center. In this project، a rain gauge and runoff gaugewere installed، and the runoff and the rainfall was recorded. Using appropriate statistical analyzes، the runoff coefficient and the volume of runoff by different values of the depth and intensity of rainfall were measured after each rainfall event. Based on these results، the runoff coefficient for the average spring rainfall events is 0. 52; it is 0. 59 for the fall season is 0. 59 and it is 0. 60 for the winter. The highest average amount of runoff was generated in winter. The average potential runoff produced from one Hectare of paved streets in the study area، in each of the seasons of fall، winter، and spring is about 200 cubic meters.

The deficiencies in water resources in the arid and semi-aridareas require adoption of procedures to combat them. One of these solutions is the use a rain water harvesting. Thus، the creation of dryland orchards in the microcatchmant method in the Gonbad area of Golestan province has been investigated in this respect. The experiment was conducted with three differentsurface treatments. In this experiment، the growth parameters of olive seedlings were investigated. This experiment that was carried out during the three years (during 2010 to 2012) has shown that with increasing the level of the basin، the vegetative parametersof the seedlingshas increased. Vegetative parameters measured include: diameter became، plant height seedling and Crown seedlings، respectively. Statistical data collected with the useof statistical methods to compare themean have been analyzed. The test results were independently compared and the significant statistical difference between the groups was completely confirmed. The mean values of the measured parameters for the three different treatments in the three year period of study in the 9، 16 and 25 square meters areas were 4. 5، 5. 3 and 6. 4 centimeters in the collar diameters; and for the plants with heights of 85، 98 and 103 cm and for crown seedlings of 45; 53 and 62 centimeters، respectively.

The exceedingly fast trend of climatic changes in recent decades that are mainly caused by industrial activities along with population growth have taken necessitated prediction of changes for the future. The impact of changes in climate on temperature and precipitation in a sub-basin of Zayandehrud (Eskandari) for the 2020 decade is predicted in this research study. The Lars-WG model is used for downscaling Had-CM3 predictions into station scale. Results of running the models show an annual increase equal to 1 degree centigrade in temperature، while a 7. 2% decrease in precipitation will occur. These changes in temperature and precipitation will be more significant during the summer time. Thus، it is expected that we shall have to find ways to deal with serious water shortages in the next decade during this season. Keywords: climate change، Eskandari، Lars-WG، Downscaling، HadCM3 Model.

The Global warming and climate change caused changes in rainfall patterns. Instead of snow، rainfalls are as precipitations which are not useful since usually they are lost as runoff or flood. Thus، proper recovery of precipitation especially snow and rain is very important، particularly in arid and semi-arid areas. By establishing rainwater harvesting systems with high runoff coefficients and storage of the runoff we can produce sustainable conditions to meet the water requirement of the plants and forest trees in the dryseasons. For this purpose، three treatment procedures including intact natural surfaces، areas covered with gravel، and use of plastic cover with gravel were selected and repeated thrice. The areas of each constructed experimental plot were 4m2squared shape، and their average slope was 11. 5-18%. The results obtained from 16 occasions of rainfall showed that the recovered runoff obtained from natural surfaces with gravel، intact natural surfaces and plastic cover with gravel treatments were 7، 12 and 48 % of the rainfall، respectively. The rainfall thresholds to initiate runoff flows in the treatments were obtainedto be 4. 4، 3. 5 and 2. 7 mm، respectively. The analysis of variance showed that the runoff from treatments were statistically significant at P<0. 01. The mean comparison revealed that the highest runoff was produced by plastic surfaces with gravel treatment and this system is suggested as an appropriate option to harvest rainwater as a result of this study.

In recent decades the Hulu Langat basin that is a strategic watershed located in Malaysia، has been exposed to extensive changes in land use pattern and consequently hydrological condition. The impact of Land Use and Cover Change (LUCC) on hydrological conditions (water discharge and sediment load) of the basin are investigated using the Soil and Water Assessment Tool (SWAT) in this study. Four land use scenarios were defined for land use change impact analysis، i. e. past، present (baseline)، future and water conservation plan. The land use maps dated 1984، 1990، 1997 and 2002 were defined as the past scenarios for LUCC impact analysis. The present scenario was defined based on the 2006 land use map. The 2020 land use map was simulated using cellular automata-Markov model and defined as the future scenario. Water conservation scenarios were produced based on guidelines published by the Malaysia’s Department of Town and Country Planning and the Department of Environment. Both model calibration and uncertainty analysis were performed using the Sequential Uncertainty Fitting (SUFI-2) algorithm. The model robustness for water discharge simulation during the period 1997-2008 was good. However، due to uncertainties that mainly result from intense urban development in the basin، its robustness for sediment load simulation was only acceptable for the calibration period of 1997-2004. The optimized model was run using different land use maps over the periods 1997-2008 and 1997-2004 for water discharge and sediment load estimation، respectively. In comparison to the baseline scenario، SWAT simulation using the past and conservative scenarios showed significant reduction in monthly direct runoff and monthly sediment load، while SWAT simulation based on the future scenario showed a significant increase in the monthly direct runoff، monthly sediment load and ground water recharge.

The Process of obtaining and gathering of water isn’t new phenomenon. Our traditional culture in this field is rich and productive. Khooshab is a traditional technique to collect runoff using autochthonous materials. Especially embankment operation is constructed in the rivers bed and flood watercourses. The age of thistraditional methodis more than four centuries. The materials of Khooshab consist of soil ofwatercourses. In addition to collecting and infiltration ofwater leads to the creating of cultivated lands. This study was conducted to provide to better understanding of the deep knowledge of local people in the harvesting of water. Attention to this indigenous knowledge is important factor for accesses to indices of sustainable development in the areas where faced with problems of water scarcity.