بررسی اندرکنش رودخانه و آبخوان در دشت بجنورد به‌وسیله اندازه‌گیری‌های میدانی و مدل‌سازی عددی

نوع مقاله : مقالات پژوهشی

نویسندگان

1 فردوسی مشهد

2 مرکز پژوهشی آب و محیط زیست شرق

چکیده

مدیریت جامع و منطقی منابع آب، مستلزم شناخت روابط بین منابع آب سطحی و زیرسطحی و مدیریت تلفیقی می‌باشد. آبخوان آبرفتی دشت بجنورد با مساحت 2/65 کیلومتر مربع در استان خراسان شمالی می‌باشد که بخش اعظم آن را منطقه شهری تشکیل می‌دهد. تأمین آب شرب از خارج محدوده آبخوان آبرفتی در سال­های اخیر افزایش ارتفاع سطح آب در بعضی نقاط دشت را در پی داشته است که باعث ایجاد مشکلاتی برای ساکنان و زیرساخت­های شهر شده است. به منظور شناخت راهکارهای کاهش این مشکلات، شبیه­سازی تراز سطح آب با استفاده از کد MODFLOW و به کمک نرم‌افزارGMS  با در نظر گرفتن رودخانه فیروزه انجام شد و نقش رودخانه در تغذیه و تبادلات با آبخوان مورد بررسی قرار گرفت. بازدیدهای میدانی به منظور اندازه­گیری دبی و عمق آب در چندین مقطع رودخانه انجام شد و از این داده‌ها برای واسنجی مدل بهره گرفته شد. مدل­سازی در حالت ماندگار برای مهرماه سال 1390 صورت گرفت و پس از واسنجی، خطای مدل برابر 53/0 متر به­دست آمد. دوره مدل­سازی غیر ماندگار از مهر ماه سال 1380 الی مهر ماه 1395 شامل ده سال واسنجی و چهار سال صحت‌سنجی بود که پس از اجرا و واسنجی مدل، میانگین خطا در دوره واسنجی به 83/0 متر و خطای دوره صحت‌سنجی به یک متر کاهش یافت. بر اساس نتایج حاصل از بیلان، رودخانه در یک قسمت از مسیر خود حدود 4/2 میلیون متر مکعب در سال آبخوان را تغذیه می­کند و در قسمتی دیگر زهکش کننده آبخوان می‌باشد. در نهایت سناریوهای ادامه روند موجود، حذف چاه­های شرب شهر بجنورد و اثر اجرای سیستم فاضلاب تا سال 2025 به مدل اعمال شد که در انتهای دوره سناریو نتایج به ترتیب حاکی از افت حدود یک متری سطح آب‌زیرزمینی، افزایش تراز سطح آب به میزان چهار متر و فرو افتادن سطح آب به میزان 5/4 متر بود.

کلیدواژه‌ها


عنوان مقاله [English]

Investigation of River‐aquifer Interactions in Bojnourd Plain Using Reach Measurements and Numerical Modeling

نویسندگان [English]

  • saeed sarvari 1
  • Ali Naghi Ziaei 1
  • Ata Joodavi 2
1 Ferdowsi Univ. of Mashhad
2 , Water Research Center and East Environment
چکیده [English]

Introduction: Understanding water budget components is crucial for making decisions regarding water resources planning and management. Surface water–groundwater interactions are commonly investigated at the river reach scale and generally classified as connected or disconnected type systems. Connected systems are either gaining surface water system, where groundwater discharges through the streambed to contribute to streamflow, or losing surface water system which loses (or recharges) water to the local groundwater system. Disconnected systems are defined by an unsaturated zone beneath the surface water system which loses water at a rate related to the hydrogeological properties of the streambed and the aquifer. These interactions have significant implications for both water quantity and quality. Seepage of fresh groundwater into a river can be important in maintaining flows during extended dry periods. This can be critical for supplying the needs of surface water users such as irrigators as well as for aquatic ecosystems. Pumping from an aquifer near a river can dramatically change the amount of this base-flow to the river. In contrast, if the groundwater is contaminated, increased groundwater discharge can have a negative effect on river water quality. The Bojnourd catchment is located in North Khorasan province. The catchment covers an area of about 1265.8 km2. The main river in this area, Firouze River, is approximately 10 km in length, and is hydraulically connected to the Bojnourd alluvial aquifer. The alluvial aquifer of Bojnourd plain with 65.2 km2 area is mostly covered by urban area. Hence, effective management of water quantity and quality issues in the Bojnourd catchment requires quantifying flow between surface water and groundwater. Furthermore, conveying water from the outside of basin caused water table to rise which made some problems for urban buildings and infrastructures. Therefore, the river and aquifer interaction needs to be studied more comprehensively.
Materials and Methods: Numerous techniques and methods are available to describe and quantify the flow between surface water and ground water. This study combined two methods, numerical modeling using MODFLOW code and reach measurements, to quantitatively evaluate groundwater/surface water interactions under highly transient conditions. The groundwater flow system of the study area was conceptualized based on borehole logs, pumping tests, and available hydrogeological and geophysical information. Moreover, field work, including measuring streamflow in three seasons, was carried out to conceptualize and quantify the groundwater/surface water interactions. Following the conceptual model, the numerical model was developed to simulate flow through the system. The model grid had 1274 active cells with a uniform cell spacing of 250×250 m. The water exchanges between the main regional river, Firouze river, and Bojnourd aquifer was simulated using the River (RIV) package. Both hydraulic head target and flux target were used to calibrate the model. The head targets were compiled from the monitoring network which contains 11 observation wells. The flux targets were located in three measurement points along the Firouze river. The data obtained from the fieldwork were used as observed values for the groundwater/surface-water exchanges. The transient model was calibrated and validated for 15 hydrological years, i.e. from 1 October 2001 to 1 October 2016
Results and Discussion: Model performance was evaluated using root-mean-square error (RMSE). The model results were in agreement with corresponding observed data, including groundwater heads and measured groundwater/surface-water exchanges. The RMSE values during calibration and validation periods were 0.83 m and 1 m, respectively. Analyzing water balances resulted from transient simulation showed that Firouze river is gaining in some reaches and losing in other reaches. In losing reaches, the total flux into the aquifer is 6.4 MCM per year. In gaining reaches, the volume of groundwater discharges through the streambed is about 4 MCM per year. Furthermore, the effect of several management scenarios, including continuing the existing condition, turning the domestic wells off and implementing a sewage system by 2025, on groundwater heads and groundwater/surface-water exchanges was examined using the numerical model. Results showed that by implementing the sewage system, the volume of water discharged to the river would decrease, but it will prevent aquifer and river contamination caused by sewage water. 
Conclusion: In this study, groundwater budget components in Bojnourd aquifer including groundwater/surface-water exchanges were calculated. The results showed that understanding of these surface water-groundwater interactions, which has been ignored in previous studies, is important for effective management of water quantity and quality issues in Bojnourd plain. Moreover, the methodology used in this study including numerical modeling and measuring flow at multiple points along the stream is effective and easy to apply to estimate the direction and magnitude of seepage on a stream reach basis.

کلیدواژه‌ها [English]

  • GMS
  • groundwater recharge
  • MODFLOW
  • river-aquifer interaction
1- Chitsazan M., Nozarpour L., Nadri A., and Farhadimanesh M. 2016. Evaluation of the hydraulic relationship between the laur Andimeshk and Dez River aquifers using the MODFLOW model. Journal of Advanced Applied Geology .17. (In Persian)
2- Chitsazan M., Chavoshi Z., and Naseri H.R. 2016. Prediction of the interaction of aquifer-river in Daszelq plain, Khuzestan province using MODFLOW model. Journal of Iranian Water Research 9(4): 139-147. (In Persian)
3- Debsarkar P., Roy P.K., Banerjee G., and Mazumdar A. 2015. Study of impact on developed groundwater system around flow fields by using numerical approach in Purulia District. Journal of Chemical and Pharmaceutical Research 7(1): 298-306.
4- Eckhardt K. 2005. How to construct recursive digital filters for baseflow separation. Hydrological Processes 19: 507–515.
5- Healy R.W. 2010. Estimating GroundWater Recharge. 1nd ed.
6- Izady A., Davary K., Alizadeh A., Ziaei A.N., Akhavan S., Alipoor A., Joodavi A., and Brusseau M.L. 2014. Groundwater conceptualization and modeling using distributed SWATbased recharge for the semi-arid agricultural Neishaboor plain, Iran. Hydrogeology Journal 23(1): 47-68.
7- Izady A., Abdalla O.A.E., Joodavi A., Karimi A., Chen M., and Tompson A. 2017. Groundwater recharge estimation in arid hardrock-alluvium aquifers using combined water-table fluctuation and groundwater balance approaches. Hydrological Processes 31: 3437–3451.
8- Jafari z., Ansari H., Faridhoseini A., Ziaei A.N., and Davari K. 2013. Using GMS to simulate the groundwater Flow in an urban Region (case study: bojnourd plain). MSc Thesis, Faculty of Agriculture, Ferdowsi University of Mashhad. (In Persian with English abstract)
9- Joodavi A., Zare M., Raeisi E., and Ahmadi M.B. 2015. A multi-compartment hydrologic model to estimate groundwater recharge in an alluvial-karst system. Arabian Journal of Geosciences.
10- Karimi Z., porhamat J., Heidarizadeh M., and Kolahchi A. 2012. Investigation of the Effect of Surface Water on Groundwater Level of Mahidsht. Earth Magazine 7(23): 63-78. (In Persian)
11- Ketabchi H., Mahmoudzadeh D., and Farhodihafdaran R. 2017. Estimation of water exchange between wetland and aquifer (case study of canyrabzan wetland). Ecohydrology 4(3): 699-709. (In persian)
12- Movahedian A., and Chitsazan M. 2014. Investigating the interaction of aquifer and Karun river in Gotvand-Aghili plain using MODFLOW model. Watershed Research 111: 9-18.
13- Mansori R., Esmaili K., Ziaei A.N., Ansari H., and Khodashenas S.R. 2012.Study of River Flow Effects on Subsurface Water Diversion Using Porous Media in Seasonal Rivers. Journal of soil and Water 26(5): 1200-1214. (In Persian with English abstract)
14- North Khorasan Regional Water Company. 2014. Report of the Groundwater Mathematical Model of Bojnourd Plain, HydroTech Toos Consulting Engineers Co.
15- North Khorasan Regional Water Company. 2011. Holistic Studies uses and resources of the city and the plain Bojnoord, Consulting Engineers Toossab.
16- Nazari R., and Joodavi A. 2014. Applied Flow and Contaminant Transport Modeling in Aquifers. Mashhad.
17- Recio B., Ibanez J., Rubio F., and Criado J.A. 2005. A decision support system for analyzing the impact of water restriction policies. Journal of Decision Support System 39(3): 385-402.
18- Sinton P., Flynn J., Dixon R., Bonton D., Smith L., and Moreno J. 2011. Modflow and more 2011-Integrated Hydrologic Modeling, International Groundwater Modeling Center (IGWMC).
19- Shaki A.A., and Adeloy A.J. 2007. Mathematical modelling of effects of Irawan irrigation project water abstractions on the Murzuq aquifer systems in Libya, Journal of Arid Environments,Article in Press, Elsevier 2: 133-156.
20- Tetreault M., and Hulley M. 2011. Modflow and more 2011-Integrated Hydrologic Modeling, International Groundwater Modeling Center (IGWMC).
21- Wang S., Shao J., Song X., Zhang Y., Huo Z., and Zhou X. 2008. Application of MODFLOW and geographical information system to groundwater flow Simulation in North Plain, China. Environmental Geology 55: 1449-1462.
22- Winter T.C., Harvey J.W., Franke O.L., and Alley W.M. 1998. Ground water and surface water; a single resource. US Geological Survey Circular 1139.
CAPTCHA Image