Optimum management of water and wastewater network in GIS environment using geospatial database, a case study on part of Ahvaz city, SW Iran K. Rngzan*, A. Mehrabi*, R. Shad**, E. Abshirini*, M. Moradzadeh* *Department of RSGIS, Faculty of science, Shahid Cahmran University, Ahvaz-Iran Email: kazemrangzan@gmail.com - Fax: 06113339338 **Department of GIS, Faculty of Geomatic, KNTU, Tehran Iran Abstract Nowadays, establishing a geospatial database is commonly the first step for managing the urban services. The aim of this paper is designing and implementing a cost-effective kind of geospatial database for managing water and wastewater networks. At first, it was essential to detect and remove different kinds of possible errors like; spatial, temporal and etc. Then, complete conceptual diagram is drawn for modeling and implementing geometric network in spatial database. After that, the geometric network designed for modeling flow is weighted based on transferring water volume, scale of pressure and the pump strength. Furthermore, customer's demand is considered as a driven defined weight, for GIS analysis function. The wastewaters, in the geometric network are weighted using pipe's diameters because of ground gradient. Finally, spatial networks functions are implemented together for optimum managing network. The final results demonstrate high ability of geospatial database for managing water and wastewater networks. 1. Introduction Utilities are the important parts of cities extension. Water and Wastewater networks plays principle role in extending different kinds of civil applications like; residential, commercial, economical and etc. This fact along with increasing the price and the environmental disturbance of water shortage indicate that why relevant companies and offices completely pay attentions to optimum exploitation of resources. GIS as a spatial information system allows simple and comprehensive tools for optimum exploiting of water and wastewater networks. Civil water and wastewater networks witch are made with high costs are in basement. In the other word, all of water and wastewater companies are earth-bed. So, most of them explore modern exploitation methods like GIS to optimum management. Most primary works in this field are concentrated a preparation of database for relevant systems and services. This databases which should be work geospatially, must be accompanied by network designing and before burial of network. Many workers have shown the ability of GIS in urban water and wastewater net work (Nobel, (1998); Ramirez (1997); Bahadur et al. (2000); De schaetzen and Boulos (2001); Nielsen (2005); Rangzan and Mehrabi, (2007)). Goal of their research was developing database and transferring information between database and water and wastewater hydraulic model. Mathiyalagan, (2004) developed an interactive WebGIS and geo-database for Florida's wetland. Their web-based tools facilities to share data globally provide end-user a cost-saving solution to access up-to-date spatial datasets customized foe specific topic to user with limited GIS knowledge. Also Bonniface and Coppins (2007) used geospatial database in their research. In this investigation, a database is established for water and wastewater network of two civil zones of Kianpars and Kianabad of Ahvaz city. This base has a projected coordinate system for keeping data with high quality and fully structured topology. It also has the ability of establishing validation rule for data management of inner users can control editing data by defining these rules and recognizing contrary and prevent entering them. A network model in the form of geometric network has useful analysis for helping and accelerating verification networks. Study area This zone is located in North West of Ahvaz (between 31° 20´ 9´´ and 31° 22´ 11´´ latitude and between 48° 40´ 14´´ and 48° 41´ 55´´ longitude). It's a crowded place which its population is increasing rapidly (Fig 1). This increasing rate of population growth is along with changing land use and making residential apartments instead villa houses. It censes some difficulties for water and wastewater networks due to seasonal heavy rains and river overflow. The gradient of zone is nearly 0.85-0.3 degree. Total length of water distribution network is 78.28 Km and it consist of 735 pipes and pipes are asbestos cement. This network is fed by a reservoir. Volume of reservoir is 50,000 m3 and it has a head which often is 110 cm. Water enters to network by 5 pumps which each of them are 3.25 m3/hour and their head is 6500m. Length of wastewater is also 57, 65 Km and consists of 4.3 concrete and asbestos cement pipes. Population of total zone is 60,000 and its extent is 5.3 Km. 2. Material and method 2.1. Data collection and quality control The results of existing analysis in GIS are depended on the correctness of input data. Collected data are in digital form and consisted of geospatial and raw tables (Aronoff, 1989). These data included of water and wastewater network components (water pipes, pumps, valves, fittings, reservoir, waste pipes and manholes) and also pavements, parcels, river and rail. In the first phase, required descriptive data completed for network analysis. Then, repetitive rows and strange phrases removed, substituted and linke src="images/d to features. Existing errors in geospatial data consisted of separation of components, overshoot, undershoot and multipart errors which are removed by definition of necessary tolerance automatically. Then, primary and foreign key attributes were defined for tables which were required in database for making relationships.  Fig 1: Location map of Kianpars and Kianabad portion of Ahvaz city SW Iran 2.2. Preparing conceptual model For defining resources of real world from the viewpoint of data and application and also extension of systems for assembling, data model is avoidable. For designing conceptual model “Entity Relationship Diagram” (ERD) in this zone, 5 entities for water network (water pipe, fitting, pump, reservoir and valve) and 2 entities for wastewater network (waste pipe and manhole) are considered. This model which is designed for assembling geometric network is shown in fig 2 and 3. In ERD model, spatial relationship and scale of its cardinality are presented among entities. It also helps to establish connectivity rules among network components while establishing geometric network.  Fig 2: ERD of water supply network in Kianpars and Kianabad (Ahvaz city)  Fig 3: ERD of wastewater network in Kianpars and Kianabad (Ahvaz city)
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