چکیده زمینه و هدف: توسعه شهرنشینی و افزایش سطوح نفوذناپذیر در بسیاری از موارد، منجر به افزایش حجم رواناب و ایجاد سیل در نواحی پایین دست شده است. یکی از روش های مفید در کاهش خطرات سیل در مناطق شهری، استحصال رواناب های شهری و استفاده از آن در مصارف غیر شرب می باشد. با توجه به توسعه شهرسازی در منطقه 22 تهران و افزایش خطر سیل، و همچنین ضرورت توسعه فضای سبز در این منطقه سعی گردیده، تا استحصال رواناب شهری به منظور تامین بخشی از آب مورد نیاز فضای سبز این منطقه صورت گیرد. این مطالعه با هدف برآورد نیاز آبی فضای سبز منطقه 22 در طول یکسال و برآورد حجم رواناب سالیانه منطقه و سپس استفاده بهینه از رواناب قابل استحصال جهت آبیاری فضای سبز می باشد. روش بررسی: به همین منظور ضمن شناسایی فضای سبز منطقه پرسشنامه هایی تهیه و با کمک متخصصین، نیاز آبی گونه های موجود در منطقه طی یکسال تخمین زده شد و سپس حجم رواناب یکساله حاصل از بارش ها محاسبه گردید. یافته‌ها: با توجه به محاسبات انجام شده نیاز آبی فضای سبز منطقه حدود 534/969/14 متر مکعب می باشد در حالیکه متوسط سالانه حجم رواناب حاصل از بارش ها حدود 441/285/33 متر مکعب تخمین زده شد. با توجه به نتایج بدست آمده چنانچه بتوان با مدیریت اصولی یک چهارم از این رواناب که حدود 360/321/8 متر مکعب است را کنترل و به مصرف آبیاری فضای سبز منطقه رسانید، می توان حدود 5/55 درصد از آب مورد نیاز این بخش، که در حال حاضر با صرف هزینه و از طریق تانکر تامین می گردد را جبران نمود. بحث و نتیجه‌گیری: با توجه به یافته های تحقیق و شرایط موجود، روش هایی از جمله سد خاکی، پشته های هلالی و لوزی شکل در جاهایی مثل پارک های جنگلی چیتگر، وردآورد، لتمال و خرگوش دره می تواند به عنوان الگوی مناسب استحصال آب در منطقه پیشنهاد گردد. Manuscript profile

Increasing the use of water and soil resources in watershed in recent years and unproductive and inappropriate use of land ecology has exacerbated the occurrence of floods. In this context, watershed management is one of the most effective ways to cope with this crisis. This research quantify the results of these activities by calculating the decreased volume and discharge due to biomechanical measures taken in the Ramyan watershed in Golestan province. Using the HEC-HMS model and taking into account the CN coefficients in three dry, moderate and wet periods, reduced peak discharge and volume with a return period of 2 to 500 years were estimated. In order to control the estimates, four events were used during the statistical period of 21 years from the hydrometric station and the rain station in the region. After optimizing the input CN values to the HEC-HMS model, peak discharge and total flood volume were estimated with accuracy of 3.16 and 11.3 percent. Investigations show that biomechanical operations can reduce the 10 years peak discharge by 40.72 percent, while the 20-year discharge will be reduced by 30.18 percent. On the other hand, hydrograph before and after biomechanical operations shows that the flood volume and peak discharge of Ramyan watershed has decreased with respect to time and the watershed management operation was effective. Thus, in general, the effect of watershed management operation emphasis on biomechanical measures on the flood discharge in the Ramyan watershed is positive. Manuscript profile

At the beginning of twenty-first century, the water crisis in the priority policy andmanagement is inside and outside of the country as principle thoroughly human, social,economic and political rulers of the country is considered abundant. The World Bank hasannounced that during 1960 and 2025, water resources in Middle East, from 3430 m3 for theeach person in year reach to 667 m3 because of population growth, degradation of naturalresources, extent and spread of deserts. Study of ecohydrology in arid and semi aridrangelands of the world is one of the newest methods for available water resourcemanagement. In this science, all of effective ecology elements on water balance equationwere reviewed. In these areas, a strong relation had been seen between ecology and hydrologyprocesses. In these areas, not only lack of precipitation, but also irregular and unpredictabledistribution of precipitation was problematic. Ecohydrology pays particular attention to theseareas of vegetation and its impact on groundwater and surface water. Manuscript profile

Vegetation cover is the first barrier for the raindrops resulting to the interception and infiltration loss. Interception as one of the main components of ecohydrology equation plays a major role in the water balance of rangelands. However, few studies have been done on the interception of rangeland plants in Iran. This study was carried out to find the interception rate in Astragalus parrowianus through the rainfall portable simulator devices. In addition, the relationship between plant structural factors such as height, large and small diameters, volume and surface of cover and rangeland physiographic factors including altitude, slope percentage and slope in the interception rate was evaluated. Data were collected and analyzed based on simple linear regression models and multivariate analysis (stepwise approach and descending). Results showed that in first group with a volume of 0.002 to 0.02 m3 and canopy cover of 642 m2, 4.421% of total amount of rainfall interception was happened while in second group with volume of 0.02 to 0.087 m3 and canopy cover of 1640 cm2, the interception rate was 1.85% out of total precipitation. In the first group, the interception rate showed a significant correlation (P≤1%) with large diameter (r=-0.73) and the canopy cover at 5% level (r=-0.51). Interception rate in the second group at 1% significant correlations with canopy cover (r=-0.93), diverse small diameter (r= -0.874), large diameter (r=-0.76) and plant volume size was calculated (r=-0.83). From the regression equations obtained in each group, the interception rate can be measured in Astragalus parrowianus without clipping and weighing. Manuscript profile