مدیریت منابع آب فضای سبز شهری شهرستان زاهدان تحت سناریوهای مختلف توسعه (مقاله علمی وزارت علوم)
درجه علمی: نشریه علمی (وزارت علوم)
آرشیو
چکیده
تصفیه فاضلاب شهری و فرآیندهایی که سعی در حذف مواد آلاینده موجود در پساب محیط های مسکونی و تجاری دارند، تأثیر بسیار زیادی بر حفاظت از محیط زیست خواهند داشت. به عبارت دیگر، پشت سرگذاشتن و طی کردن مراحل تصفیه فاضلاب شهری (تصفیه فاضلاب بهداشتی و انسانی) منجر به بالا بردن کیفیت فاضلاب می گردد. به طوریکه می توان این فاضلاب را برای مصارف کشاورزی و باغبانی و بدون نگرانی بابت وجود آلاینده های شیمیایی و بیولوژیکی در آنها مورد استفاده قرار داد. شهر زاهدان به دلیل موقعیت جغرافیایی و واقع شدن در منطقه گرم و خشک همواره با کمبود آب روبه رو بوده است و در سال های اخیر با توجه به گسترش شهرنشینی و افزایش مهاجرت نیاز مبرم به توسعه فضای سبز شهری به وجود آمده است که نیاز به تعریف منابع آبی غیر متعارف، جهت رفع کمبود آب مورد تقاضای فضای سبز شهری به وجود آمده است. در این پژوهش با استفاده از شبیه سازی رفتاری و بکارگیری پویایی سیستم و استفاده از نرم افزار Vensim، سناریوهای قابل اجرا اعمال و شبیه سازی شد. سناریوهایی شامل 1- افزایش راندمان خط آبرسانی و برقراری آورد هیرمند از 80 درصد به 95 درصد 2- افزایش راندمان آبیاری از 35 درصد به 75 درصد و 3- کاهش سطح زیر کشت اراضی در زاهدان به 50 درصد برای یک افق 12 ساله ارائه شد. نتایج حاصل از شبیه سازی سناریوها نشان می دهد که اگر زاهدان تحت شرایط فعلی مدیریت منابع آب پیش رود شاهد عدم تعادل و کمبود آب و افزایش تقاضا برای فضای سبز خواهد بود اما با اعمال سه سناریوی دیگر شاهد افزایش تعادل در منابع آبی و به تبع آن کاهش کمبود آب، افزایش تصفیه فاضلاب و افزایش میزان تولید پساب فاضلاب جهت مصرف و همچنین کاهش تقاضای فضای سبز از منابع آبی متعارف خواهد بود. لذا در بعد مدیریتی پیشنهاد می گردد سیاست گذاری نسبت به جمع آوری و انتقال فاضلاب می بایست با توجه به موارد متعددی از جمله ملاحظات اقتصادی، امکان استفاده دوباره از فاضلاب در محل تولید آن و موارد دیگر مورد توجه قرار گیرد. جمع آوری و انتقال فاضلاب یکی از ارکان مدیریت فاضلاب محسوب می شود.Water Resources Management of Urban Green Spaces in Zahedan City under Different Development Scenarios
Introduction Today, the concept of cities cannot be compared without effective green space in its various forms. The importance of urban green spaces is such that today the existence of this use is considered as one of the indicators of the development of societies. Therefore, the development of urban green space is bound to meet its water needs, and despite the fact that Iran is located in a hot and dry region and facing a water crisis, the importance of defining and using non-conventional water resources for managers is evident. One of the non-conventional water sources is urban sewage effluent. Due to the lack of rainfall throughout the year, the water situation in Zahedan city is such that the supply of water needed by the green space sector faces a serious challenge. Considering the low per capita green space in Zahedan city, which is approximately 4 square meters per person, and the distance between this per capita and the country's is 12 square meters. Methodology In this study, we decided to use non-conventional water to replace conventional water to irrigate urban green spaces by analyzing the dynamics of the system and considering the water crisis in Zahedan and the importance of green spaces with the management of urban sewage effluents. Therefore, modeling steps are presented in system dynamics analysis. Identification of similar boundaries Introduction of system subsystems The following modeling is similar to water resources Enter variables such as population Entering variables such as urban sewage treatment Green space water consumption modeling Similar to resources and consumption of Zahedan city in VENSIM Similar validation (1) Borders like: The borders created are considered to be similar to Zahedan city in terms of location and for the horizon of 1415 in terms of time. The input data is from 1385 to 1402. In the created simulation, it has been tried to consider all the beneficiaries of water resources, including domestic, green, industrial, agricultural and environmental consumers, and the effects can be taken and presented for each of them. (2) Introducing the following system clones: Based on the presented conceptual model, four sub-models including underground water resources, population, wastewater treatment and urban green space are considered. In the following, brief explanations will be given about each of these similarities. (3) Validation similar to: In order to verify the validity, the behavior repetition test is used. This test focuses on checking similar outputs. In such a way that the data produced by the simulator should be compared with the historical data, in order to find out how well the trend of the data produced by the simulator corresponds with the historical data. For comparison, the variables of underground water volume, water demand of Zahedan city, water demand of Zahedan green area, lack of available resources and needs of users are used and the statistical tools of coefficient of explanation and average in the absolute limit of error are used in order to check the similar behavior. In this research, based on the information obtained and the data collected during the years 2006 to 2023, the scenarios of 2023 to 1415 were predicted. It has been predicted and estimated with the help of Vensim software. The initial scenarios include 1- increasing the efficiency of the water supply line and establishing the Hirmand water supply from 80% to 95%, 2- increasing the irrigation efficiency from 35% to 75%, and 3- reducing the cultivated area in Zahedan city to 50%. Findings In the basic scenario of the water resources system, the water balance in 2036 will decrease to 39685 million cubic meters per year, and water shortage will occur in the city. Under the wastewater treatment system, purified water increases by 7055.07 million cubic meters per year. Under the system of green space, urban green space in Zahedan city increases by 19194 square meters per year. The results of the application of the scenario of increasing the efficiency of the water supply line (S1) by 95%, in the sub-system of water resources, the water balance in the years 2023 and 2036 at the rate of -408.88 and -37391 million cubic meters per year, which compared to the base scenario is about It has increased by 2000 million cubic meters per year and water shortage has decreased as a result. Wastewater treatment in 2023 and 2036 has increased by 278.19 and 15605 million cubic meters per year compared to the basic conditions. Also, the water demand of urban green spaces has decreased by 316.56 and 18142 million cubic meters per year in 2023 and 2036. The results of the estimation of the scenario of 75% increase in irrigation efficiency (S2) show that in the sub-system of water resources, the water balance in the years 2023 and 2036 was -52.380 and -17175 million cubic meters per year, which compared to the base scenario has increased by about 22,000 million cubic meters per year, and water scarcity has decreased accordingly. Wastewater treatment in 2023 and 2036 was 141.68 and 8717 million cubic meters per year, which has increased compared to the basic conditions. Also, the water demand of urban green space has decreased by 300.64 and 10078 million cubic meters per year in 2023 and 2036.The results of the implementation of the 50% reduction scenario of the total cultivated area (S3) show that in the sub-system of water resources, the water balance in the years 2023 and 2036 was -334.05 and -6410 million cubic meters per year, which Compared to the base scenario, it has increased by about 33,000 million cubic meters per year, and as a result, the water shortage has decreased to a great extent. Wastewater treatment in 2023 and 2036 was 99.159 and 1919 million cubic meters per year, which has decreased compared to the basic conditions. Also, the water demand of urban green spaces has decreased by 237.97 and 5036 million cubic meters per year in 2023 and 2036. Discussion and Conclusion Approximately 70 to 90% of the water consumed in every community becomes wastewater, so the management of wastewater production is equal to the management of water consumption. The results of the simulation of the scenarios show that if Zahedan continues under the current conditions of water resources management, it will witness an imbalance and shortage of water and an increase in the demand for green space, but by applying the other three scenarios, it will witness an increase in the balance in water resources and consequently Reducing water shortage, increasing wastewater treatment, and increasing the production of wastewater for consumption, as well as reducing the demand of green space from water sources will be conventional. Wastewater production management can be considered as the most logical and least expensive way to manage wastewater. In fact, neglecting this part will undoubtedly cause a waste of resources and facilities. The collection and transfer of wastewater should be considered according to several factors, including economic considerations, the possibility of reusing wastewater at its production site, and other issues. Collecting and transporting wastewater is one of the pillars of wastewater management.
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