Integrated management of water demand in urban and industry sectors by connection of WEAP and MODFLOW models (case study: Bojnourd basin)

Background and objectives: Population growth, agricultural and industrial development, degradation of surface water resources, groundwater levels drop are among the major factor causing water scarcity. The integrated management of groundwater and surface waters could serves as a solution to solve these challenges. In other words, sustainable water resources can be achieved through Integrated Water Resources Management, which is the comprehensive approach to all the components that affect and influences the status of water resources. With this approach, the importance of management tools such as integrated water resource simulation models to help planners and managers of this sector is increasingly evident. Connecting the WEAP model to MODFLOW allows the values calculated by WEAP to be sent to the MODFLOW for input on groundwater influxes, river levels, groundwater withdrawals (pumping) and surface runoffs. After it, the groundwater level, sub-streams between the aquifers and the flow between surface and underground water are sent to the WEAP as input of the next step of the calculation.
The purpose of this research was to investigate the effects of scenarios related to demand and available water resources, integrated water management in the urban sector and sewage system application in Bojnourd region.

Materials and methods: In this study, with using a water resources simulation model (WEAP) and its connection to groundwater simulation model (MODFLOW), water consumptions for Bojnourd basin was evaluated. Calibration and validation of both models has done under taken data based on 6 (from 2005-06 to 2010-11) and 2 years (from 2011-12 to 2012-13) respectively. Then different management scenarios, including current state water resources scenario, dam's drinking water supply for Bojnord city via transferring water from Shirin Dareh dam, developing sewage systems and finally combination of 2 last scenarios were considered. Under these scenarios, projections for a period of 28 years (from 2013-14 to 2040-41) and its effects on water resources of Bojnord basin were studied.The hydrometric station data of Babaaman at the outlet of the Bojnourd basin, which is the only hydrometric station representing this basin, was used to calibrate the WEAP model. Also, data from four rain-sensing stations, one evaporation station and one synoptic station were obtained from the year 1380 to 1390.Demographic data and Urban water demand and rural demand, population and consumption per person was assessed. Industry sector Water demand is estimated monthly. According to geological studies, the Bojnourd basin has two types of alluvial and limestone aquifers, both of which are defined in the model. Then, sensitive and effective parameters were determined by calculating the sensitivity percentage of the mode. Finally, the results of calibration and validation of the model were done from three indicators of Nash-Sutcliff (Ef), Coefficient of determination (R2) and Root Mean Square Error (RMSE), respectively, and the reliability index were used to evaluate the scenarios.
Results: The results showed that Simultaneous applying multiple water management strategies seems to be better than any of its individual states, reducing water withdrawing on various resources. Reliability of water supply in the whole complex scenario, for urban drinking water, rural and industry purposes were estimated around 100, 100 and 65.3 percent respectively. As a result of this scenario, the annual recharge of the aquifer with 5.39 million cubic meters per year can be relative balance between harvesting and recharge.
Conclusion: it can be concluded that reliable results will be obtained from simultaneous simulation of drinking and industry water management.
Keywords: aquifer, Bojnourd, simulation, water resources management