جستجوی مقالات مرتبط با کلیدواژه « شمال شرق ایران » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

Earth dams can be a prehistoric phenomenon. These structures are designed to exploit surface water resources in certain positions in natural landscapes. In the plateau of Iran, surface water sources are generally seasonal. Seasons, when surface water flows abundantly, are late winter to the first half of spring. Meanwhile, according to the agricultural calendar, the peak demand for water for most agricultural products is the last month of spring and the first month of summer. According to this calendar, earth dams are generally made of natural materials such as soil and stone and are used temporarily for several months. As long as the earthen dams are made of natural materials without any changes in them, due to the naturalness of all the materials used, it is not possible to identify them not only from prehistory but also from recent centuries. But in a special case that is introduced and analyzed in this article, the construction of earthen dams with molded mud bricks in a prehistoric settlement has caused that in contemporary times, after about five thousand years, it is possible to identify and introduce the remains of the mud bricks dam with a function exactly similar to the earthen dams. This article introduces the analysis of the location and possible functions of the earth-mud bricks dam in the Damghani prehistoric site on the southeastern edge of the contemporary city of Sabzevar in Razavi Khorasan province. The earth-mud bricks dam is a mud bricks structure that is placed on a clay soil foundation and the two ends of the structure lead to natural soil mounds. In general, for such a structure, exploitation of surface water sources is suggested, but the exact type of exploitation, as will be discussed, requires additional studies. Exploitation for drinking water purposes of the Damghani prehistoric settlement, exploitation for agriculture, and simultaneous exploitation for drinking water purposes, air conditioning of settlement spaces, agriculture and animal husbandry are hypotheses that can be investigated and evaluated. Based on today's and near-contemporary examples, the third hypothesis is more likely.

One of the most fundamental processes, which influence climate and weather, both global and local scales that a fact which gives it the status of agriculture, is Evapotranspiration (ET). In irrigation and water resources management, ecosystem modelers, environmental assessment and solar energy system, accurate assessment of evapotranspiration is essential. Potential evapotranspiration (ET) has commonly applied to calculate the actual evapotranspiration, which was difficult to estimate by lysimeter measurement and water balance approach under field conditions. Until now, many methods have reported to estimating ET, however, due to the availability of the observed data, it is difficult to choose the optimal method. In this study, to determination of the best potential evapotranspiration method for the Khorasan Razavi Province, three temperature-based methods, Hargreaves–Samani (HS), Hamon (HAM) and Linacre (LIN) and five radiation-based methods, Jensen-Haise (JH), Makkink (MAK), McGuinness and Bordne (MB), Abtew (ABT), and Priestley–Taylor (PT), were compared with PM at yearly scale, using long-term (11-67 years) data from 13 meteorology stations. Indicators, viz. The correlation coefficient (CC), Relative bias (BIAS), normalized root mean squared error (NRMSE) and Relative error(Re) were used to evaluate the performance of ET estimations by the above-mentioned eight methods. The results showed that the performance of the methods in ET estimation varied among regions; ETLIN overestimated ET, while others underestimated. In Dargaz and Golmakan, ETHS yielded similar estimations to that of ETPM, while, in Torbate-jam and Khaf, ETLIN showed better performances. Also in Mashhad and Gonabad, ETHAM, in Neyshabour, ETJH and in Torbat-e Heydarieh, ETABT showed better performances. But in Fariman, Kashmar, Sabzevar, Sarakhs and Quchan, all methods showed poor performance. It indicated that ETPM is acceptable for ET simulation for the yearly timescale in these areas.    ​