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IST-Africa 2013 Conference Proceedings Paul Cunningham and Miriam Cunningham (Eds) IIMC International Information Management Corporation, 2013 ISBN: 978-1-905824-38-0

ICT for Flood Risk Management Strategies a GIS-based MCDA (M) Approach Avelino MONDLANE1, Karin HANSSON2 and Oliver POPOV3 Stockholm University Department of Computer and Systems Science – DSV Isafjordsgatan 39, FORUM 100, Kista 16440 Stockholm Sweden Tel: +46 767467646, Fax: +46 87039025 Email: [email protected], [email protected], [email protected] 1 Eduardo Mondlane University, Centre for Informatics – Main Campus, Julius Nyerere Ave. No. 12 P.O. Box 257, Maputo Mozambique Tel: +258 821 492601, Fax: +258 21 494755, Email: [email protected]

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Abstract: This paper discusses the application of Analytical Hierarchical (AHP) on Geographic Information System (GIS) based Multcriteria Decision Analysis (Making) MCDA (M) for flood risk management strategies at the Limpopo River Basin in Mozambique. An analytical process is carried out based on GIS Decision Support System (DSS) taking into account the role of ICT and interest of both the decision makers and different stakeholders namely the householders and economic agents, within the basin. The study aims to provide the different stakeholders and decision makers with a decision tool and it focuses on the Mozambican section Limpopo River Basin as part of the national strategies to mitigate the exposure to both floods and droughts that cyclically affect the region. Keywords: AHP, GIS, ICT, MCDA(M), Flood risk management strategy.

1. Introduction The Limpopo Basin covers 412,000 km2, with a complex drainage system flowing from South Africa downstream to Mozambique (Figure 1). Rising as the Crocodile River in the Witwatersrand of South Africa, the Limpopo flows northeast along the border of South Africa with Botswana, eastward between South Africa and Zimbabwe, then southeast across Mozambique, before emptying into the Indian Ocean [6].

Figure1: Limpopo River Basin Characteristics; Source: [15] Copyright © 2013 The authors

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This basin is shared by 4 riparian countries and each of them has its own specificity and water policies and regulations, what makes the water management complex, nevertheless the existence of regional instruments in the last decades [8]; this motivates our application of AHP, GIS-Multicriteria Decision Analysis (Making) MCDA(M) for the analysis of the different layers of the basin. The Limpopo River Basin is one of the most cyclically affected by both floods and drought in the region, particularly in the Mozambique section, the reason of choice of this part of the basin for the present research. 1.1 Purpose and Motivation In this paper the words Multcriteria decision Analysis (MCDA) and Multcriteria Decision making (MCDM) are used to mean the same concepts, therefore they are interchanged and or combined within Multicriteria Decision Analysis (Making) MCDA (M). Geographic Information Systems (GIS) are database that usually have a spatial component to the storage and data processing, therefore their capability to store and create maplike products [5]. Geographic Information Systems have been playing a progressive role in the field of decision making in the last decades with special emphasis to Multcriteria decision-making (MCDM) processes, nevertheless the relative few MCDA(M) publications in Africa and America, figure 2 below, when compared to Asia and Europe [7].

Figure 2: Comparative Analysis of MCDA (M) Papers by Continents, Source: [7].

The purpose of this paper is to emphasize the role of Information and Communication Technologies (ICTs) in the field of decision making by applying GIS concepts within Multicriteria decision Analysis (making) MCDA(M) process for flood risk management strategies, taking into account the Limpopo River Basin in Southern Africa. The paper, basically apply the Analytical Hierarchical Process (AHP) a Multicriteria Decision Analysis (MCDA) tool, through a combination of different analytical layers, using ArcGIS 10.1, and we aim to create awareness and provide a decision tool to the decision makers, particularly the stakeholders involved in the process of design and implementation of flood risk management strategies.

2.

Objectives

Generally, the objective of this research is to provide the stakeholders with a decision tool based on Information and Communication Technologies (ICTs) by applying the Analytical Hierarchical Process (AHP) tools in the Multicriteria Decision Making based on GIS, for flood risk management strategies in the Limpopo River Basin. By applying AHP, this research aims to: 1. Highlight the importance of ICT in the process of Multcriteria decision Analysis (making) using GIS as Decision Support System for land use and water planning and management. Copyright © 2013 The authors


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2. Create awareness to different stakeholders involved in the decision process of the importance analytical and hierarchical process of choices, when a decision has to be made, by using GIS given the complexity of the process. 3. Provide the decision makers ant district, provincial and national levels with a practical decision technique that can applied in the multiple choices and conflicting tradeoffs, using AHP GIS based.

3.

Methodology

According to many researchers and practitioners in [3], MCDA(M) is well-suited for eliciting values and preferences and evaluating stakeholder interests [10], [11], [9], [12]. However, having the right combination of people is an essential element in the MCDA(M) process, and of course decision makers, stakeholders, scientists, and engineers all play important roles [3]. Figure 3 below illustrates ICT based MCDA(M) applications in a method dialog and GIS respectively, whose practice is in fashion in recent decades. Different methods and tools of MCDA(M) are technically available with special emphasis of ICT software based, such as illustrated in figure 3 a) below from [7] were we have namely listed the MAVT, Topsis, PROMETHEE, AHP, MAUT, ProMAA, FMAA, Fuzzy MAVT and Flow Sort just to mention some. Given the complexity of their application and mathematical requirements to solve some logical algorithms most of them are software based, therefore the important role of ICT application within MCDA(M). On another hand, figure 3 b) illustrates the hierarchal GIS based profile of different layers under analysis, typically applicable for the AHP MCDA(M) tools for water use and management, a top down planning process, that is suggestive for the three level stakeholders and decision makers management, namely the strategic, tactical and operational levels .

Figure 3: ICT Based MCDA(M) Source: a)[7],b)[2]

As GIS-based, AHP, MCDA(M) becomes one of the most useful methods for spatial planning and management [4] and with its proliferation, ever since the 1950s, multiple criteria decision making methods MCDA(M) have evolved as a major tool to assist decision makers with analyzing and solving multiple criteria decision problems[13]. Figure 4 below show an example of GIS-MCDA applied for urban infrastructure by [12]. For the complex flood risk management process that cyclically affect cities such as Chokwe and Xai-Xai downstream of Mozambique over Limpopo River Basin and most of the arable area within Gaza Province, the GIS-based AHP method can provide a way out to mitigate these hazards. Section 4 provide more precise analytical details over the study area.

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Figure 4:.Multi-criteria Planning of Urban Infrastructure Systems, Source: [14]

The GIS-based AHP gained high popularity because of its capacity to integrate a large amount of heterogeneous data and the ease in obtaining the weights of enormous alternatives (criteria), and therefore, it is applied in a wide variety of decision making problems [4]. “It calculates the needed importance weighting factors associated with criterion map layers by the help of a preference matrix where all identified relevant criteria are compared against each other with reproducible preference factors. Then the weights can be aggregated with the criterion maps in a way similar to weighted combination methods” [4]. An illustration of AHP Multcriteria is given in Figure 5, where a Decision Support System principle is applied for Multcriteria management within different modules.

Figure 5: An AHP Multcriteria Decision Making Process, Source: [2]

A part from the combining different layers of the object under research, the MCDA(M) combines the management structural layers of the decision makers segments (stakeholders) with the different modules of decision process, hence the role of ICT as Decision Support System (DSS).



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4. Developments One of the most applied principles is the so called sieve mapping; figure 6 below is a commonly used multi-criteria, GIS-based planning approach that allows stakeholders to assess their objectives and choices.

Figure 6: Sieve Mapping is a Multi-Step Process, Source [3]

“Each constraint or opportunity “criterion” is mapped as a rasterized “sieve,” figure and the area of concern is “passed through” the “sieves” systematically in a definitive sequence to reveal areas suitable for the intended use” [3]. The structure of AHP tool implies the decomposition of a problem into a hierarchy that captures the essential elements of the decision issue. The comparative principle of AHP is based on pair-wise comparison technique of the decomposed elements within a given level of layers. Figure 7 below illustrates the Gaza Province, the study area of Limpopo River Basin Mozambique Section developed on ArGIS 10.1. Using the CENACARTA data.

Figure 7: GIS Illustration of Limpopo River Basin with Highlights to Mozambique Section Source: Authors, data from CENACARTA.



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Figure 8: GIS Illustration of Limpopo River Basin with Highlights to Flood Model Source: Authors, data from CENACARTA.

Figure 8 illustrates a two layers AHP method where a flood model is incorporated within the Limpopo River Basin, Mozambique section. This show to what extent the area is exposed to floods and to what magnitude this area can be flooded when an event occurs.

Figure 9:A 4 Layers AHP- GIS Illustration of Limpopo River Basin with Buffer Source: Authors, data from CENACARTA.

In Figure 9, we illustrate the impact of the floods, using the flood model level 3 against economic and social assets such as Population density and other demographic assets on the left and at least a buffers outputs on the right side.



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Figure 10: 10 Layers AHP- GIS Illustration of Limpopo River Basin with Buffer and index catalog Source: Authors, data from CENACARTA.

By clustering more assets of 10 layers within the AHP-GIS based is shown on figure 10, where we can see the magnitude of exposure. This matches with the reality if one evaluates the impact of 2000 and the recent January 2013 floods that resulted on thousands of householders displaced, many economic assets damaged and millions of dollars required to get life back on track within the basin. Nevertheless this can be minimized by creating a buffers zone around the basin, which apart from the economic implications for investment it is also a subject of analysis for those who are involved in the planning process at district, provincial and national level, when planning and designing flood risk management strategies for this basin.

5.

Results

The Limpopo river Basin downstream in Mozambique is highly exposed to both floods and drought and whenever they occur it results on both economic and social assets. Flood Risk Management Strategic Planning Process (FRMSPP) can be exercised at all levels taking into account that this is dynamic process that involve the District, Provincial and National authorities (different stakeholders and decision makers) and tradeoffs and conflicting objectives are always in place when a decision has to be taken. The application of AHP-GIS based Multcriteria decision analysis (making), more precisely the Analytical Hierarchical Process has shown that ICT can widely contribute to manage the land use in general and flood risk management strategies in particular. Figure 6 shows a portion of Mozambique within the Limpopo River Basin where it is clear to what extent the valley is prone to floods. By incorporating the flood model, figures 8 and 9, we can see that the same province in Mozambique previously shown in figure 7 is subject to extreme floods, and this can be referred to year 2000 floods that resulted in many casualties and economic losses. The GIS strategy applied to deal with such floods is to simulate a buffer zone that for our research was defined in a range of 3 Km and it is highlighted in figure 9 with a 4 layers AHP analysis with a report shown in the 3rd column of the map. Lastly, figure 10 shows a 10 layers AHP map that can be analysed with details in a comprehensive manner toward a definition of flood risk management strategy in order to choose possible intervention of the interested stakeholder and the three decision making levels. Copyright © 2013 The authors


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6.

Business Benefits

The business benefit gained from this research is that we express the awareness to the decision makers and different stakeholders at District, Provincial and National levels in order to bear in mind the importance of AHP GIS based MCDA(M) tools. Several strategies can be applied by using different MCDA(M) tools, but the objective of this study was to provide and ICT based technique using GIS within MCDA(M) as Decision Support System for Flood Risk Management Strategies.

7.

Conclusions

MCDA(M), particularly the AHP GIS based is a strong analytical tool that provides a decomposed analysis of a problem. Limpopo River Basin is one of the most complexes in Southern Africa therefore the present study cannot cover most of the details and problems that the flood risk management require. Nevertheless the usage of GIS within MCDM is one of the techniques that can be applied within the wide range of strategies of flood risk management. Our challenge is to continue this research provided the ICTs facilities for MCD(A)M techniques and Decision Support System for land use and water management Planning.

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