FREE GIS SOFTWARE AND THEİR USAGE İN THE RİVER BASİN MANAGEMENT

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1 FREE GIS SOFTWARE AND THEİR USAGE İN THE RİVER BASİN MANAGEMENT Prof.Dr. Kamil ŞENGÖNÜL University of Istanbul,Faculty of Forestry,Department of Watershed Management, 34473, Bahçeköy,İSTANBUL, Yrd.Doç.Dr. O.Yalçın YILMAZ University of Istanbul,Faculty of Forestry,Department of Surveying and Photogrammetry, 34473, Bahçeköy,İSTANBUL, ABSTRACT Todays, principle approaches for the natural resources management under sustainability concept is planning in the watershed base. A natural resource management plan has three different stages. First stage is to make a inventory, second stage is to obtain physical, ecological and biological structure of the resource and the final stage is making a development plan. Watersheds, as a planning unit have different ecosystems going on the base of soil-water and plant relations. Variations of the balance between these ecosystems effect water yield and soil stability and also other production of the watersheds. The last 15 years watershed managers are working on the modeling by using some watershed parameter to find out water yield, sediment discharge, nutrient discharge, flood hazard and like other outputs in a watershed. Some of these parameters are related with watershed geomorphology. In past, traditional methods were using to describe topographical characters and surface morphology of the river basins. Todays, modern analysis supported by the use of Geographic Information Systems(GIS) can easily and rapidly provide same parameters. In this paper, developments of geoinformation technology in the open source and free software community especially GRASS, being a free geographic information system software, and its capability to provide topographic properties of a sample basin and simulate water flow and erosion/deposition model, will be explained. Keywords: Hydrologic Modeling, Free Software, GRASS

2 PRACTICES ON RIVER BASIN MANAGEMENT INTRODUCTION Hydrology engineers and scientists have been dealt with gross simplifications for a long time. Gross simplifications such as only slope value or hydrologic roughness at river basin scale has serve well when limited computer capacities and absence of soil, terrain, land cover, rainfall data (Vieux, 2005). However it is inevitable to use GIS at the large and complex areas and some alternative evaluations required. Because basin is a spatial object has large boundaries and complex natural sequence of events, neither only traditional methods nor gross simplifications cannot sufficient to manage it. Whereas GIS either provide raw spatial data or capabilities of analysis and modeling to solve this complex phenomenon, it has become as a support tools for researchers (Hofierka, Mitasova, Mitas, 2002). Geographic information technologies affected directly from developments in the computer software and hardware area in the last quarter century. Process being done with traditional methods formerly, moving into digital environment and computer was virtually laboratory of these area professionals. Thus the new era has started through being made the process rapidly and easily that is time consuming or impossible to be done. Software in the geographic information technologies area has increase quantitatively and developed qualitatively from they were being borne. Although there are less than ten leader software firm, hundreds of software firm is active in this area worldwide. According to Daratechʹs report nine leader firms has the 86 % of GIS software worldwide market share (Figure 1) (THAIL ve CAMPINS 2004). Figure 1. Top nine GIS firms market share based on worldwide GIS revenue (software only) in 2001) (THAIL ve CAMPINS 2004)

3 246 INTERNATIONAL CONGRESS ON RIVER BASIN MANAGEMENT Figure 2. GIS Industry Pie (TARAFDAR et al. 2004) Figure 3. GIS Industry Growth (TARAFDAR et al. 2004) Although proprietary software cost has decrease relative to past years, it is constitute great deal of expenses in this sector. Worldwide GIS trade volume was 1.84 billion dollars in 2003 and 64 % of this was determined as software expenses (Figure 2-3) (TARAFDAR et al. 2004). Professionals and related researches in this area affected negatively from proprietary software high fees. But institutions heavily use information and communication technologies need more financial resources to achieve rapidly changing international standards (CEZAYİRLİOĞLU 2002). Free software is a matter of the usersʹ freedom to run, copy, distribute, study, change and improve the software. More precisely, it refers to four kinds of freedom, for the users of the software (STALLMAN 2005): The freedom to run the program, for any purpose (freedom 0). The freedom to study how the program works, and adapt it to your needs (freedom 1). Access to the source code is a precondition for this. The freedom to redistribute copies so you can help your neighbor (freedom 2). The freedom to improve the program, and release your improvements to the public, so that the whole community benefits (freedom 3). Access to the source code is a precondition for this.

4 PRACTICES ON RIVER BASIN MANAGEMENT 247 Over the past decade Geographic Information Systems (GIS) have entered many new disciplines and have become part of general computational infrastructure. Therefore it is not surprising that geoinformation technology is also being developed within the Open Source and Free Software community, well known for its GNU/Linux system (MITASOVA ve NETELER 2005). Free software philosophy has made valuable contributions in the GIS area as well as others. Besides the widely used proprietary systems, an open source and free software GIS plays an important role in adaptation of GIS technology by stimulating new experimental approaches and by providing access to GIS for users who cannot or do not want to use proprietary products (MITASOVA ve NETELER 2002). Full access to the source code is particularly important for GIS because the underlying algorithms can be complex and can greatly influence the results of spatial analysis and modeling. To fully understand the system s functionality, it is important to be able to review and verify the implementation of a particular function. While an average user may not be able to trace bugs within a complex source code, there is a number of specialists willing to test, analyze and fix the code. The more sophisticated users can modify the existing code for their specific applications rather than having to write a new code from scratch. The different backgrounds and expertise of these developers contribute to faster and more effective software development (MITASOVA ve NETELER 2005). Free software efforts have important developments in geographic information technologies and produce about 309 programs and plugins (Freegis Web P.1). The GRASS, being the most successful and widely used will be mentioned below. 2. GRASS (Geographic Resources Analysis Support System) Commonly referred to as GRASS, this is a Geographic Information System (GIS) used for geospatial data management and analysis, image processing, graphics/maps production, spatial modeling, and visualization. GRASS is currently used in academic and commercial settings around the world, as well as by many governmental agencies and environmental consulting companies (GRASS Web P.1). GRASS was developed during the period by the U.S. Army Corps of Engineers Construction Engineering Research Laboratory (CERL) in Champaign, Illinois, to support land management at military installations. Since the late 1980s coordination of GRASS development was handled by the GRASS Inter-Agency Steering Committee (GIASC). When CERL ceased its official sponsorship of GRASS, GRASS lost most of its support and users in the following transition period. After forming a new development team in 1997, the turning point in the recent GRASS history was the adoption of GNU GPL in By this GRASS has embraced the Free Software philosophy (MITASOVA ve NETELER 2004, GRASS Web P.2).

5 248 INTERNATIONAL CONGRESS ON RIVER BASIN MANAGEMENT Development, maintenance, distribution and support of GRASS software is realized by the main internet site and the mirrors such as in Turkey Bugs and wishes come from GRASS users via internet responded as soon as by GRASS developers. Also required documents and sample data has been reached via internet. Besides stable version, GRASS has a development version that updated daily or weekly by the way CVS (Concurrent Versioning System). Also GRASS users can solve their problems through mail archive. GRASS was successfully coupled with a number of hydrological and water quality models, including ANSWERS, AGNPS, TOPMODEL, SWAT, and SWIM to facilitate input of spatially distributed hydrological models. The raster formulation of GRASS is very attractive for use in spatially distributed hydrological modelling (Ogden, Garbrecht, DeBarry, ve Johnson, 2001). Besides vector, raster 2D/3D, image processing, functions GRASS has many ecological modelling such as hydrology, erosion, and wild fire (GRASS Web P.3). In this paper erosion/deposition modeling and other hydrologic capabilities put forwarded through usage of spearfish sample dataset. 3- Capabilities of GRASS for the Management and Modeling of Basin GRASS advantages such as being a free software, able to run integrated to various software (statistics, database management, web mapping, sketching, visualization etc.) (Figure 4), flexible structure for modeling and data import-export offer possibilities for basin management, risk and prediction mapping, basin-meteorology studies, and geomorphologic operations. In this section, erosion/deposition and water flow simulation and geomorphologic operations capabilities put forwarded only. JGrass developed in Java by CUDAM, Hydrologis, and ICENS has various hydrologic functions besides many GRASS hydrologic modeling tools (JGrass Web P.1). Simulation of water and sediment were realized by r.sim.water and r.sim.sediment module of GRASS software but other operations by JGrass software. Although many operations realized by GRASS, JGrass software was referred for integrity. Figure 4. GRASS and integrated applications

6 PRACTICES ON RIVER BASIN MANAGEMENT 249 In a river basin, estimation of the water yield and transporting soil material by discharging water and their changing with time and different land use practices has to be known by watershed managers. In fact, water yield as a final production pass through the soil-plant system in the watershed could not be easily estimated. Modeling works and simulation techniques needs dependable figures related parameters. These parameters can be illustrated by a scheme below (Figure 5). Forest floor Soil surface Geomorphology Basin shape Drainage characteristics Land use techniques Soil properties Plant Cover Precipitations and Characteristics Soil-Plant Intersection Soil water Structural properties Plant cover management factor Surface flow Water+soil Figure 5. Parameters releted with soil-plant cover systems Geomorphology as shown in figure.5 has an important role in watershed hydrology. Geomorphometrical works support valuable parameters will be used in simulation modeling for water-soil relations of the watershed. Digital Elevation Models (DEM), also easily obtained from satellite images, can be used to extract geomorphometrical information as classified below (Ghesla, E. and Rigon, R. 2006) ; Basic topographic attributes, Basin related analysis, Network measurements, Hillslope analysis, Hydro-geomorphic index. Before beginning to extract some output from a DEM with related basin, some operations are required on the DEM data. Elimination of depression point from DEM: This process eliminates possible depression point from DEM and opens the way to calculate the flow directions correctly (Figure 6).

7 250 INTERNATIONAL CONGRESS ON RIVER BASIN MANAGEMENT Flow directions and drainage directions: Surface flow moves along the land surface depending on the topography with 8 directions (Figure.7). Flow directions of each DEM cell is connected with neighbor 8 cells and it gives drainage directions towards the steepest downward slope (Figure 8). Total contributing area: After all these calculation with flow directions and drainage direction, each points of DEM totally give total contributing area. Slope and curvatures: After pit filling and extracting drainage directions, slope which runoff is moving on, curvatures (convex, concave, and planar sites), and their combination can be calculated. Extracting network: Extraction of the drainage network by using described properties mentioned above, may be obtained three different way; o by using total contributing areas (Figure 9.a), o by the combination of the total contributing areas and slope (Figure 9.b), o by using topographic classes (Figure 9.c). The drainage network maps obtained by three different ways have not important differences, but second way gives larger scale creeks than others. Extracting watershed: The last step of the preliminary work on the DEM is giving the coordinates of the water outlet and extracting of the related watershed (Figure 9.d). Figure 6 Depressionless elevation Figure 7. D8 scheme

8 251 PRACTICES ON RIVER BASIN MANAGEMENT Figure 8 Flow directions map (a) (b) (c) (d) Figure 9 a)network by total contributing areas, b) network by total contributing areas and slope, c) network by topographic classes, d)extracted related basin

9 252 INTERNATIONAL CONGRESS ON RIVER BASIN MANAGEMENT 3.1. Basic Topographic Properties A given extracted watershed, aspect, slope, curvatures, drainage direction, flow directions, gradient, Laplace operator, Ab (draining area per length unit), and such kind of topographic properties can be calculated (Figure 10). Figure 10 Slope map Figure 11 Euclidian distances to outlet 3.2. Basin Related Measures Diameter (the distance between basin outlet and the point on the boundary farest from it), distance of euclidea ( Euclidian distance of each point from the outlet of related basin) (Figure 11), principal axes and such kind of extractions related to characteristic of the basin.

10 PRACTICES ON RIVER BASIN MANAGEMENT Drainage Network Related Measures Drainage network has a direct effect on the stream flow and also size of the pick flows originates from the basin.(özhan 2004). First of all, network has to be extracted by preferred way of three (figue 12.a). Then drainage density (figure 12.b) (creek length for unit area), hacklength (figure 12.c), hackstream and net numbering (figure 12.d), hierarchical numbering can also be calculated. (a) (b) (c) (d) Figure 12. a)drainage network, b)drainage density, c)hacklength, d)net numbering and subbasin

11 254 INTERNATIONAL CONGRESS ON RIVER BASIN MANAGEMENT 3.4. Hillslope Analyses The hillslope analysis gives us hillslope to channel distance (figure 13) (each point on the slope distance from the network), geomorphic classes, and topographic classes can be analyzed (figure 14). Figure 13 Hillslope to channel distance Figure 14 Topographic classes

12 PRACTICES ON RIVER BASIN MANAGEMENT HYDRO-GEOMORPHIC INDEX This index recognizes surface flow capacity from a given area. It is related to saturation index(figure 15). Figure 15 Topographic index 3.6.Water Flow and Erosion Modeling Beside the analyses of geomorphometric characteristics, various hyrologic modeling can also be done. GRASS has some hyrologic modules such as ANSWERS, AGNPS, KINEROS, TOPMODEL, r.water.fea(storm water runoff), CASC2D, SWAT. However while GRASS is continuously developing software, these modules can be adopt to a new version. Some of them were updated and run with the latest version of GRASS but others only run with previous versions. Here, r.sim.water and r.sim.sediment module integrated latest version were used to show water flow and erosion/deposition simulation. r.sim.water and r.sim.sediment are based on path sampling method. It has been used for a number of environment applications including simulation and transport of dissolved and suspended substances in water, groundwater modeling, and soil erosion by overland flow (Hofierka, Mitasova, and Mitas 2002). r.sim.water is a landscape scale, simulation model of overland flow designed for spatially variable terrain, soil, cover and rainfall excess conditions. A 2D shallow water flow is described by the bivariate form of Saint Venant equations. The key inputs of the model include elevation, flow gradient vector given by first-order partial derivatives of elevation field, rainfall excess rate and a surface roughness coefficient given by Manningʹs n. Output includes water depth raster map in [m], water discharge raster in [m3/s] (Figure 16) (GRASS Web P.5).

13 256 INTERNATIONAL CONGRESS ON RIVER BASIN MANAGEMENT r.sim.sediment is a landscape scale, simulation model of soil erosion, sediment transport and deposition caused by flowing water designed for spatially variable terrain, soil, cover and rainfall excess conditions. The soil erosion model is based on the theory used in the USDA WEPP hillslope erosion model, but it has been generalized to 2D flow. Key inputs of the model include the following raster maps: elevation, flow gradient given by the first-order partial derivatives of elevation field, overland flow water depth, detachment capacity coefficient, transport capacity coefficient, critical shear stress and surface roughness coefficient called Manningʹs n. Output includes transport capacity raster map in [kg/ms], transport capacity limited erosion/deposition raster map [kg/m 2 s], sediment flow rate raster map [kg/ms], and net erosion/deposition raster map [kg/m 2 s] (Figure 17) (GRASS Web P.6) Figure 16: Water depth simulation map Figure 17: erosion/deposion map 4. Results and Discussions As it has been tried to explain that, today, geomorphometric characteristics of watershed and hydrologic modeling can be easily and soundly realized by using geographic information system. Geographic information systems provide spatially distributed variables such as rainfall, plant cover, soil etc. to especially hydrologic modeling through direct or indirect ways. Today, there is a lot of geographic information system software and hydrologic modeling tools available. On the contrary of proprietary software, free software users may see the source code and have freedom to run, to change, to redistribute, and to improve program. Thus researchers and software developers make valuable contribution to any model consuming less time and labor.

14 PRACTICES ON RIVER BASIN MANAGEMENT 257 Finally, these explanations showed that, a number of geomorphological operations and hydrologic modeling works could easily be realized by free software as use of the GRASS. REFERENCES Cezayirlioğlu, S., (2002): Bilişim Harcamaları, internet adresi: /bilisim.php Freegis Web P.1: GRASS Web P.1: GRASS Web P.2: GRASS Web P.3http://grass.itc.it/intro/modelintegration.html GRASS Web P.4: GRASS Web P.5: GRASS Web P.6: Hofierka, J., Mitasova, H., Mitas, L., (2002): GRASS and modeling landscape processes using duality between particles and fields, Proceedings of the Open Source GIS-GRASS users conference 2002-Trento,Italy,11-13 September 2002 Mitasova, H., Neteler, M., (2002): Freedom in geoinformation science and software development: A GRASS GIS contribution, Proceedings of the Open Source Free Software GIS. GRASS users conference Trento, Italy, September 2002 Mitasova, H., Neteler, M., (2004): GRASS as Open Source Free Software GIS: Accomplishments and Perspectives, Transactions in GIS, 8(2): Neteler, M., Mitasova, H., (2005): Open Source GIS: A GRASS GIS Approach 424 pages, Kluwer Academic Publishers, Boston, Dordrecht, ISBN (Also published as ebook, ISBN ). Ogden, F.L., J. Garbrecht, P.A. DeBarry, and L.E. Johnson, 2001, GIS and Distributed Watershed Models. II: Modules, Interfaces, and Models, J. Hydrologic Engineering, 6(6): Özhan S., (2004): Havza Amenajmanı, İ.Ü. Rektörlük Yayın No: 4510, Orman Fakültesi Yayın No:481 Ghesla, E., Rigon,R., 2006: JGrass 2.0 A Tutorial for the Management of Digital Terrain Models, Stallman, R.M., (2005): The Free Software Definition, internet adresi: gnu.org/philosophy/free-sw.html, son erişim: Tarafdar, A., et.all (2004): Setting benchmarks?, internet adresi: son erişim: Thail, I.T., Campins, M., (2004): Mapping the Geospatial Community, Part One, internet adresi: article/ articledetail.jsp?id=101550, Son erişim: