Reza Aghayari Samian; Ali Mohammad Khorshid Doust; Saeed Jahanbakhsh Asl; Aida Hosseini Baghanam
Abstract
The aim of this study was to predict changes in temperature, precipitation and evaluate the effects of climate change on the status of surface runoff in the Aras catchment. Climatic conditions were simulated in LARS-WG software environment under RCP8.5 scenario. Using the modified Trent White experimental ...
Read More
The aim of this study was to predict changes in temperature, precipitation and evaluate the effects of climate change on the status of surface runoff in the Aras catchment. Climatic conditions were simulated in LARS-WG software environment under RCP8.5 scenario. Using the modified Trent White experimental model, the amount of potential evapotranspiration was estimated for both observation and simulation periods. To ensure the validity of the model, the mean error orthography (RMSE), and the determination coefficient and Nash-Sutcliffe efficiency coefficient (ENS) were used. Also, modeling of surface runoff changes in GIS software environment and SWAT plugin was performed. After forming hydrological units (HRU), the baseline model for surface runoff changes was selected to calibrate and validate the model. The results show that by modeling climatic data during the simulation period, the amount of temperature, evapotranspiration and transpiration will increase, and in contrast, the amount of precipitation has occurred and the flow rate will decrease superficially. The results of validation showed that the accuracy of the model in the selected stations was high and for the precipitation parameter due to its discontinuous nature, the correlation between the data is less than the temperature parameter and different. The results of hydrometric modeling of the basins showed that the Nash-Sutcliffe value is close to 1 and the correlation coefficient between the data is 0.99, which indicates the high efficiency of the model for simulating and estimating climate change and its effects on surface runoff.
Meysam Yari; Somayeh Soltani-Gerdefaramarzi; Mohsen Ghasemi; Rouhollah Taghizadeh
Volume 6, Issue 21 , March 2020, , Pages 203-225
Abstract
1-Introduction Given the growing population and the increasing need for food, water and soil conservation are of great value. In the context of conservation of soil and water resources, information on the amount of runoff production and erosion to achieve sustainable development is the basis for planning ...
Read More
1-Introduction Given the growing population and the increasing need for food, water and soil conservation are of great value. In the context of conservation of soil and water resources, information on the amount of runoff production and erosion to achieve sustainable development is the basis for planning and decision making. Therefore, careful investigation of surface runoff and floods is an important and key step in planning and managing optimal water resources. One of the factors affecting the characteristics of surface runoff is land-use changes at different basin levels (Melesse and Shih, 2002). Land use is influenced by two components of human needs and environmental processes. Inaccurate land-use changes will disrupt the water cycle from natural equilibrium, resulting in devastating floods, including economic damage, loss of life, loss of water, and consequently reduced water resources (Jakeman et al., 2005). During the last two decades, the Qhareh-su watershed, particularly its downstream, has been experiencing rapid growth in the construction and expansion of residential structures. Human activities and changes in the basin have affected the natural arrangement of stream processes that transmit water and sediment from upstream to downstream. Human interventions are one of the major hazardous issues in this basin that causes changes in the pattern of surface currents and natural conditions of the catchments and encroachment on rivers and streams. In this regard, the present study aimed to investigate the role of land-use change on runoff in a part of Qhareh-su watershed in Ardebil province over a period of almost 20 years due to the availability of information and access to satellite images of different time periods. 2-Methodology The study area consists of a part of Qhareh-su watershed located in Ardabil province with an area of 2162.6283 km2. The minimum and maximum elevation of the mentioned watershed are 1280 and 3829 m respectively, and its average slope is 11.57%. Land use in this area often includes dry and irrigated agriculture, pasture, forest, and residential areas. The aim of the current research is to study the effect of different land uses and its changes during the years 1992-2012 on the surface runoff in a part of Qhareh-su, Ardabil watershed. At first, the maps of land use and curve number in the mentioned years were gathered and the area of each of the units was extracted. In the following, the process of land-use changes in the cases of the study period and its effect on changing the specific retention (S) and curve number were calculated and the height of runoff was estimated using the SCS method. 3-Results The results showed that during the case of the study period, area of forest, water farming, and wasteland land uses were decreased by 2.54%, 16.69%, and 1.19% respectively and the area of the rangeland, dry farming, and urban land uses were increased by 5.74%, 12.39%, 2.29% respectively. These changes have caused the increase of curve number from 78.57 to 79.77 in the years 1992 and 2012, respectively and following the decrease of the specific retention (S) from 69.28 mm in the year 1992 to 64.42 mm in the year 2012. Also, runoff height has increased from 263.4 mm in the year 1992 to 297.07 mm in the year 2012 (11.33%). Calculation of correlation coefficient between different land uses and curve number and runoff height showed that these variables have a direct relationship with rangeland, dry farming, and urban land uses while they have an inverse relationship with the forest, water farming, and wasteland. 4-Discussion and conclusion In the present study, the results of the study showed that land-use change due to its effect on the curve number of the studied basin causes a change in the surface runoff. During this 20-year period, land use has changed and this land-use change has tended to decrease from 1992 to 2012 land use including residential, pasture and dryland areas increased by 2.29%, 12.39% and 5.74% respectively, as well as forest, water and wastewater land use decreased by 2.54%, 16.69% and 1.19%, respectively. As a result, its curve number has increased, followed by a runoff height of 11.33%. This shows that in a natural ecosystem, land use and environmental changes, especially vegetation and land use affect the hydrological responses such as flooding and erosion and sedimentation rate in the area. Ultimately, it will cause severe economic and social damages. Changes in the total volume of runoff and changes in hydrological balance are the most important effects of land-use change on watershed hydrology.
Sahar Forotan; Alireza ILdoromi; Hamid Nouri; Matab Safari Shad
Volume 6, Issue 20 , December 2019, , Pages 1-20
Abstract
1- Introduction Land use change is a hydrological challenge for urban watershed management that effects on the management methods through surface runoff changes. Remote sensing, GIS techniques and satellite imagery can be used to improve and accelerate the management of natural resources and urban areas. ...
Read More
1- Introduction Land use change is a hydrological challenge for urban watershed management that effects on the management methods through surface runoff changes. Remote sensing, GIS techniques and satellite imagery can be used to improve and accelerate the management of natural resources and urban areas. This study investigates on the relationship between urban development and runoff values using hydrological modeling, GIS and remote sensing. First, the land use maps of the city of Asad abad were prepared using TM and ETM + sensors of Landsat 5 and 7 in May, 1992, 2002 and 2014. For supervised classification and estimate of surface runoff were used maximum likelihood method and Resources Conservation Service National (NRCS-CN) respectively. The maps of land use, curves number and runoff amount were calculated and plotted. The results showed that surface runoff has been increased about 15.8 % due to increase of 4/59 % of urban land use. Management of atmospheric precipitation and surface runoff from watersheds that are a factor in collecting and transporting hazardous pollutants while passing through streets, streets and other urban areas. Risk management is inevitable in relation to public health and urban environmental resources. Increasing the impenetrable levels caused by urbanization and construction of the building on permeable soils, naturally, has decreased the permeable levels of the basin, which is capable of absorbing part of the rainfall, and thus has increased the total amount of runoff in the city. One of the important issues of urban development is the change in surface runoff. So that the delay time of the hydrograph and the base time of the flood is reduced and, consequently, with an equal volume of flood, the peak flood discharge with urban development will be more than the pre-development, in addition, the runoff coefficient also increases (Amir Ahmadi, 2011:92). Regarding the management and optimization of watersheds, accurate prediction of outflow runoff can be very effective in optimizing watershed management to prevent regional flood rebound. Despite the nonlinear relations, the uncertainty and the lack of clarity and the characteristics of time and place variables in the flow systems, none of the proposed statistical and conceptual models have been able to be considered as a superior and capable model in order to accurately model rainfall and runoff. To be known. Remote sensing and GIS technology is one of the most effective and efficient technologies for environmental change and resource management that provides updated information for management purposes (Janson, 2012: 86). Therefore, this tool can be used to study urban development. Considering the previous studies and the importance of the phenomenon of physical development of the city and increasing the impenetrable levels on the relations of rainfall, urban runoff is very important with regard to the urban development process using an efficient tool such as remote sensing along with hydrological models (GIS Special Website, 2014: 1) The city of Asadabad is also no exception because of the increase in inertia levels following the expansion of the city. The location of the city is such that it has spread in three watersheds, and this form of expansion, as well as the lack of such a study, requires the study of urban runoff and The impact of urban development on production runoff in the area is doubled. The present study attempts to investigate the physical development of Asadabad in 1992, 2002, 2014 and its effect on runoff rainfall relations. 2- Methodology The city of Asad Abad, in the area of 1195 km2, forms 6.1% of the area of Hamedan province. The average elevation is 1607 meters.The Annual rainfall is between 350 and 500 mm (Aka Iran,2014:1). In this study, the relationship between urban development with distributed hydrological modeling of the integrated approach of remote sensing and geographic information system was used. Landsat satellite data was used to detect land cover changes (Kavosi and Vatan khah, 2013:4). The SCS method estimates runoff in unobstructed watersheds according to rainfall and the characteristics of the watersheds. Basically, this method will be valid when runoff is due to rainfall, and it is not effective at a time when snowfall. The American Conservation Survey (CNS) Curve Number (CN) method is one of the most common methods for estimating and forecasting flood volume and runoff and flood altitude (Mahdavi, 2009: 86). In this research, the average monthly long-term average was calculated in inches. Then, layer the point rainfall in Arc GIS, and digital calls and using IDW interpolation was to be the second (Javadi, 2011: 59). To estimate the runoff of the study area, we calculated the weighted mean of runoff. For this purpose, the data was transmitted from the descriptive table in the Arc GIS software to the Excel environment (Zhang, 2014: 956). After calculating the total runoff heights, the values obtained were retrieved in millimeters in the tables and graphs. In this research, all of the above was done in three periods of time, 1992, 2002, and 2014, we tried to use the results of 1992 and 2014 to review the changes and to use the 2002 changes to verify. So the results are presented every three times. 3- Results Land use classification maps in Arc GIS software procurement and since the purpose of assessing changes in three different periods, a guide map has been changed for better. After the land use was extracted in the time periods studied, the area of each user and the percentage of the area of each user were calculated. Generally between the years 1992 and 2014 in the area of other Land use 5.45% (equivalent to 63.9 square kilometers) declined. The urban and non-urban usage map was extracted from the land use classification map for three periods of the study, in three periods of 1992, 2002, and 2014, which were obtained in the Arc GIS environment. After extraction of urban and non-urban when the study area and the percentage of urban and non-urban area was calculated in Excel. In order to better understand the relations between runoff rainfall in the study area, rainfall, runoff height was calculated and presented according to the curve number. The results of the study of the impact of urban development on runoff variations are presented at the time of study. By changing the type of use, including the change in area in each polyglone, the calculated CN values will vary in the polyhedron, which results in changes in the runoff height in each polyhedron. By changing the type of use, including the change in area in each polyglone, the calculated CN values will vary in the polyhedron, which results in changes in the runoff height in each polyhedron. According to the results, between 1995 and 2014, urban land increased by 4.95% (equivalent to 57.7 km2), and in the period from 2002 to 2014, urban land increased by 42.3% (equivalent to 127 / 40 sq. Km), and in this period the construction rate has been higher than the previous period. However, urban runoff runoff from 2002 to 2014 increased by 11.29% over the period from 1992 to 2002. Urban development is not the only one in metropolises. It is also important in a small city such as Assadabad. Because it will affect the relations of runoff precipitation. If the runoff height, which is a small number in the city, would be 350 m 3, this volume of runoff in a small town is significant and sometimes dangerous. 4- Discussion and conclusion In the present study, we tried to investigate the impact of urban development on runoff using remote sensing and its integration with GIS. Finally, it was found that using remote sensing; we can consider the variation of runoff from urban development with an accurate precision. It was also determined that urban development in addition to rainfall has been effective on runoff due to the increasing urban use that is related to construction development, industrial development and road construction development. In general, the use of remote sensing because of the cost reduction of field operations, and especially because of the reduction in the time needed to analyze the issues, can be considered as possible solutions to improve the level of water resources management. In addition, using this tool, this opportunity is created for researchers and executives to evaluate different management scenarios (which cannot be executed in a short time without heavy cost), and by analyzing the results, the best Made a decision. It is suggested to use different methods of runoff estimation and compare their results with the results obtained in this study as well as a hydrological model to study the runoff rainfall relationships and compare its results with the results of this study.In order to better study land use changes (especially urban development studies), in different years, it is necessary to use a satellite data format that is also available on a given date. To study more precisely, the relationships between rainfall runoff and time intervals increase. And the last suggestion is to use long-term returns to better predict and understand the impact of urban development on runoff variations.
