تحلیلی بر جمعیت‌پذیری و توسعۀ شهری با تاکید بر پایداری منابع آب (مطالعۀ موردی: شهر یزد)

در پژوهش پیش رو، در مرحله اول به ارزیابی پایداری منابع آب شهر یزد براساس مدل‌های توسعه شهری پایدار پرداخته شد و سپس جمعیت بهینه یزد براساس تامین آب مورد نیاز در سال 1395 تعیین شد. بر‌اساس ماهیت هدف‌گذاری، از روش تحقیق ترکیبی (اطلاعات کیفی پشتوانه‌ای برای اطلاعات کمی) استفاده شد. در این پژوهش، با استفاده از مطالعات کتابخانه‌ای، فرم‌های پایدار شهری بررسی و در ادامه، مدل‌های پایداری منابع آب شناسایی شد. وضعیت منابع آبی استان، دشت یزداردکان و شهر یزد با استفاده از اسناد مرتبط تعیین و سپس با استفاده از تحلیل‌های کمی، جمعیت بهینه شهر بر‌اساس دو گزینه تولید و مصرف آب محاسبه شد. نتایج پژوهش، نشان می‌دهد دشت یزداردکان فقط 2 درصد از منابع آب زیرزمینی استان را دارد؛ در‌حالی‌که 58/82 درصد جمعیت شهری استان، در شهر یزد ساکن‌اند و 80 درصد آب مورد نیاز از منابع سطحی تامین می‌شود که متعلق به آب انتقالی از زاینده‌رود در فاصله 330 کیلومتری است؛ بنابراین برای تعیین اندازه بهینه جمعیت و پایداری شهر بر‌اساس مدل‌های ویلیامز و هال، شهر یزد در ارتباط با منابع آبی، شهر پایداری نیست و براساس عدم وابستگی به خارج از حوزه نفوذ، ادامه حیات در آن ممکن نیست و حتی با وابستگی به خارج از حوزه نفوذ (آب انتقالی از زاینده‌رود) 59000 نفر جمعیت مازاد دارد. از این رو، باید در جهت کنترل جمعیت از یک سو و مصرف بهینه آب از سوی دیگر، تدابیر لازم اندیشیده شود.

Stability of Water Resources Based On Optimal Loading of Population and Urban Development (Case Study: Yazd, Iran)

IntroductionIran is located in an arid region with negligible precipitation, as average downfall is under the third of that of the world average. Yazd province is placed in dry and desert area and has 100 mm precipitation in year. Yazd as one of industrial city in our country was confronted with population traits and migration. This growth caused the requisition for water consumption increase. Requisition has caused the level of underground waters in mean in 30 years period. Thus, answering to the requests and procurement of water require supplying water connected to nonrenewable resources and out of penetration basin. For inhabitation of regional and national tension crisis in the research program, it is required to have solutions for supplying needed water of the city.MethodologyTo this end, urban development forms were examined by library studies and then sustainability models concerned with water and sewage network. They identified the status of water resources in Yazd province and Yazd Ardakan plain. This was determined using relevant documents and then quantitative analysis to calculate the optimal population of the city based on two options for production and consumption of water. The type and manner of this research is descriptive and analytic using combinational qualitative and quantitative analysis. Using of library researches, civil resistant form were investigated in continuation. Situation of province’s water resources, ArdakanYazd plain and Yazd city were determined by relevant documents and then by using of quantitative analysis, city optimal population based on water production and water consumption.Results and discussionThe present research, first of all, is devoted to the assessment of sustainability of Yazd concerning water resources based on sustainable urban development models and then touches on the optimal population of Yazd according to the options for water supply in 2016 with regard to the water transferred from Zayande rood to Yazd. This is to examine the second phase of water transfer as well as water transfer project from Persian Gulf based on goal setting which applied mixed research method. To determine water deficit rate of the inhabitant population, we calculated difference of water need average from inhabitant population and the resources.To determine excess population in the water deficit rate for the population (30.3 milion cubuc meter in year), we calculated equivalent to 83 million liter for optimum population.ConclusionThe results have demonstrated that Yazd –Ardekan plain has just 2 percent of underground water resources. While 82.58 percent of population in the province are inhabited in Yazd city and 80 percent of needed water is provided by surface resources. Water from Zayanderod, this water resources in distance of 330 kilometer of Yazd city based on resistant civil models. Evidently population decentralization as a policy along promotion of people using water include reduction of consumption per capita, management of water system, reduction of casualties, progressive in cease of water rate price and reduction of  domesticated consumption. Decrease in drinkable water from consumption can be an effectual step in improvement of water resources situation.