مجله سامانه های سطوح آبگیر باران
سال دهم شماره 1 (پیاپی 32، بهار 1401)

New approaches to urban runoff management seek to reduce the volume and discharge of rainfall peaks as well as the amount of pollutants in urban areas to a level that is reminiscent of rainfall runoff in the decades before urban development. SWMM software is one of the best models to help in this field and it can be used to study the effects of using water harvesting methods on the volume of runoff and peak flow and thus reduce flooding of roads. Simulation of the drainage network in the north of Birjand city showed that the sewerage network of Birjand city does not have the necessary efficiency to pass floods with different return periods and is flooded in different parts. If the problem is not solved by the relevant organizations, in the not too distant future, it will witness a large flood and as a result, irreparable damage will be undeniable. For this purpose, using two methods of holding ponds and collecting water from the roofs, which can be used at a lower cost than other methods of water extraction; , in this study was examined. Considering that the use of water extraction systems in the whole basin is economically unfeasible and justified. In most studies, this system is used only in a part of the field. As a result, by applying rainwater extraction methods in Birjand urban watershed, we can see an 80% reduction in runoff volume in Birjand. On the other hand, the use of ponds in the green space of the city can help irrigate the green space and in addition to saving urban water consumption, is also effective in reducing the peak discharge of floods.

The water shortage crisis that is sweeping the globe today has posed serious harm and threat to people around the world. Meanwhile, Iran is one of the water-scarce countries due to its location in the arid and semi-arid belt and fluctuations in rainfall. The water status in most of its regions is in a state of tension and sometimes crisis. The pervasive nature of water and the existence of numerous human and environmental factors affecting its reliability have greatly complicated the interactions between the human-environmental dimensions. Therefore, the study of these complex environmental systems that are affected by human actions is a major scientific challenge. This challenge must bridge the gap between the natural sciences and the social sciences and dominate modeling at different scales. Therefore, there is a need to integrate knowledge from the natural and social sciences. In this regard, the purpose of this study is to analyze the water crisis and the concept of water security by presenting a framework for Human-Environment System (HES) interactions in the Neishabur Plain watershed. In this regard, first, the process of changing the water issue in the Neishabur Plain watershed during 2011-2020 was investigated, and then, according to the identification of the prevailing situation in the watershed, considering the influence of various human and natural factors in the current crisis, to identify the main factors affecting the occurrence of the crisis and determining how they interact and feedback for a comprehensive analysis of the water crisis and the consequences of this water shortage in the region. The results of the investigation of the water issue in the area generally show a decrease in precipitation, warming of the air, increase in evaporation and transpiration, dryness, and more dehydration. This is while the largest volume of water harvesting in the basin (ca. 450 million m3 in the 2019-2020 water year) is also dedicated to the agricultural sector. In addition, the results show that understanding the hierarchical levels of environmental awareness and ultimately learning and practice based on key components and interactions identified by the HES framework, facilitates the analysis of system complexity.

The frequency of precipitation extreme event can cause flood or change the drought period. Accurate understanding of these changes is necessary to take action to reduce these effects. In this research, temporal and spatial changes of 14 precipitation indices for eight synoptic stations in the North and West of the country were investigated. For this purpose, after reconstructing the daily precipitation indices defined by ETCCDI were evaluated using RClimdex software. To evaluate heavy precipitation, indices of very wet days, extremely wet days, number of days with precipitation of more than 10, 20, and 25 mm and distribution of the top 60, 40, and 20 daily precipitations were evaluated. The result showed that the trend indices of extremely wet days (R99p) and 20, 40, and 60 precipitation events in Rasht, Ramsar, Bandar Anzali and Khoramabad stations were positive and it was negative at the other stations. Total precipitation index (PRCPTOT) in all stations expect Babolsar had a negative and significant trend. The trend of simple daily intensity, Max. 1-day precipitation and Max. 5-day precipitation indices in the most stations in the North and West of the country were positive and insignificant. The trend of the number of consecutive dry days (CDD) in all stations in the North of the country was positive, which indicates increase in the length of the dry season. Also, the number of consecutive wet (CWD) in the western part the country had a negative trend, which indicates a decrease in the number of wet days. The result of this study showed that precipitation indices in a climatic zone have a spatial discontinuity and the behavior of precipitation is towards extreme value.

Awareness of water demand is of particular importance for its policy in urban management. Predicting water demand in the future will allow managers to take the necessary measures regarding sustainable water supply, given the constraints and crises ahead. The purpose of this study is to compare multivariate regression and ARIMA models to predict water demand in Mashhad. In this study, first, the main variables affecting water demand including rainfall, temperature, and population were determined and then the required data were collected from relevant organizations. After checking the accuracy and homogeneity of the data, water demand was estimated by two models of multivariate regression and ARIMA. The results showed that for data training, the determination coefficient and Nash coefficient were 0.81 and 0.77 respectively for the multivariate regression model and 0.77 and 0.73 for the ARIMA model, and the same coefficients for training data are respectively 0.86 and 0.87 for the multivariate regression model and 0.79 and 0.73 for the ARIMA model. Therefore, the multivariate regression model has a better performance in terms of prediction due to the high determination coefficient and being in the very good category of the Nash coefficient, and it can be used as an acceptable method for predicting water demand compared to the ARIMA model.

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.

Agriculture in Lorestan Province is based on irrigated and rainfed agriculture, which uses two sources of surface water and groundwater. One of the most important natural hazards affecting the Lorestan Province agriculture is the occurrence of drought and its consequences. The main purpose of this study is to investigate the effects of drought on irrigated agriculture in this province. The data used included characteristics of irrigated agriculture, characteristics of water resources used in irrigated agriculture, land use map, and drought indices. The results showed that the increasing trend of drought and repetition of long-term drought and wet cycles in Lorestan Province is evident. In addition, drought events with different intensities have occurred during the study period and the time distribution of these periods can be seen overall 36-year period. Also, the results of the correlation analysis between the yield of irrigated crops, especially wheat and barley, with the different drought indices during the period 1991-2017 indicate a positive and direct relationship between the yield of irrigated plants and the values of drought indices. In terms of time, the highest correlation index is observed between yield and drought indices on a time scale of one to six months, and on longer time scales, the correlation value decreases. One of the main reasons for this condition is that short-term drought events affect rainfed agriculture and pasture vegetation and longer-term drought events have a greater impact on irrigated agriculture due to the greater dependence of irrigated agriculture on surface and groundwater resources. Finally, it can be said that the increase in drought and heat stress in Lorestan Province has reduced yields and increased the water needs of various irrigated crops.