Implementation of an integrated decision support system (IDSS) for water management in Souss-Massa Morocco

Dr. Leslie Dolcine
Senior Consultant
Info-Electronics Systems (IES) Inc.
Mail id: leslie@info-electronics.com

Abstract

This paper presents the implementation results of an Integrated Decision Support system (IDSS) designed specifically for the Souss-Massa Hydraulic Basin Agency (AHBSM). This project has been developed to provide AHBSM with an updated spatial database, the appropriate tools and the know-how for a better support in the management and arbitration of precarious water resources. The conceptual model of the database has been designed to take into account the entire role and mission of the water agency. The application developed proposed a solution to four problems identified with the heads of the Agency: ground water availability, reservoir management, soil erosion and flood risk mapping.

Using earth observation products, with the help of the Morocco Royal Center for Remote Sensing, the development of the IDSS has been successfully completed by providing to the water agency a spatial geodatabase with an updated and high resolution DEM, land cover map and modeling tools. These tools developed by the implementation and integration of applications meet specific requirements of the agency. These applications have been designed with global or local objectives such as: erosion mapping, flood risk area reservoir management and ground water potential. Beyond the technical and methodological components, the realization of IDSS highlighted the importance, in a project of this kind, of a strong partnership with local stakeholders and staff training. The project was funded in part by the Canadian Space Agency.

Key words: Geographic information system (GIS); Integrated Decision Support System (IDSS); Watershed management; land use; spatial analysis.

1 PROJECT BACKGROUND
The countries of the Eastern Mediterranean region, such as Morocco are exposed to many challenges related to management of water resources. Since 1995, water management in Morocco has been governed by Law 10-95 (1995). This law is the third action plan to pull water policy in Morocco, the first one, in 1967 was dominated by the construction of large irrigation dams, and the second, by 1984, focused on developing small and medium-sized dams. The implementation of the law (10-95) is entrusted to basin agencies that must rely on a set of principles which deal with a) the public nature of water resources; b) planning and resource allocation based on consultation with stakeholders; c) the regulation of activities to deal with the scarcity, vulnerability and the risks inherent in the use of water resources.

2 UNDERSTANDING THE PROBLEM

The main problem in the Souss-Massa basin is the integrated management of water resources. The basin area of Souss-Massa covers approximately 28000 km2 for a potential irrigable land in the order of 250000 ha. The catchment area is served by a set of eight dams to capacity ranging from 2 Mm3 and 180 Mm3 allowing a maximum storage in surface waters of more than 450 Mm3, in addition, the plains above two continuing aquifers with a capacity estimated at 467.7 Mm3. The region of Souss-Massa in itself produces around 30% of citrus exports and 25% of vegetable production in Morocco. Along with the strength of its agricultural development, the region of Souss-Massa, especially the Agadir urban region is also a very popular tourist destination, the leading one in Morocco. The development of SIAD_TIGERS and the implementation of applications were especially designed to meet the needs of the ABSHM Agency in carrying out its mission coming from the Bill 10-95. On the basis of the scarce water resource of the region, it embraces from water quantity or quality, structures, distribution, risk associated with floods, royalties, to education relate to water stakes.

3 ACCOMPANYING THE DECISION-MAKING PROCESS
To embrace such a mission, the Agency must take into account the social dimensions, the dynamics of space-time changes as well as the legal and institutional aspects. In the purpose to help this decision-making process, we have worked with the Agency, to highlight particular issues and to offer appropriate solutions, by example: 1) for the planning problem: How to grant concessions and ensure the proper management of water resources in the basin? We implemented the SIAD_TIGERS decision support system. 2) for the information problem: How to improve knowledge of the trends (short and long term) the effect of changes in land cover land use? We prepared a multi-scale land use land cover information base (LULC) 3) for the management problem: How to manage the dam and reservoirs to provide the best allocation of water, taking into account the year to year variation of the rain also to cope with risks of water shortage or mitigate the effect of drought? We elaborated a reservoir Management tool 4) for the protection problem: How to better protect the population from the devastating effects of flash floods and torrential floods? We developed a flood mapping application 5) for the problem of Prevention: How to avoid overuse of the groundwater, the detection of new groundwater potentialities and awareness of the actors in relation to these challenges? We engineered an application on the global-local management for groundwater.

SIAD_TIGERS proposes an ensemble of solutions based on GIS, tools for decision support, graphical representations and systems modeling. Through SIAD_TIGERS, we have developed a comprehensive understanding (conceptual) of the different issues affecting the management of water resources in the basin of Souss-Massa. This comprehensive understanding has been later translated into a data model (with different phases conceptual, logical and physical). The data model was implemented and organized to simulate the conditions regulating the Souss-Massa basin and to answer problems identified with the decision makers of the basin agency. A set of applications was later developed that take advantage of the capabilities of coupling Geographical Information Systems (GIS) and modeling tools (groundwater management, reservoir management, water erosion, and flood). This implementation has been carried out in three main phase: 1) Conceptualization incorporating various phases of data modeling and implementation of the geodatabase 2) Operational capabilities consisting of demonstrating the operational capabilities of SAID_TIGERS through the resolution of targeted spatial problems 3) Ease of use corresponding to the development of a toolbar integrating the main applications developed within SIAD_TIGERS.

4 IMPLEMENTATION

4.1 Development of the Conceptual Model of the Geodatabase
SIAD_TIGERS has been designed to answer some lead-questions: How to improve the decisionmaking process in the basin and ensure proper management of water resources in the basin? And second, how to improve knowledge on short and long term trends and the effect in land use changes? SAID_TIGERS must meet the purpose of assisting in the management of the basin. The system has been structured gradually through different phases from the conceptual model, to logical and physical model. The achievement of these models required a data enrichment (inventory, updating and structuring spatial data) a paradigm change in data organization from the point of view of the customer (theme, service) to a data organization from the point of view of the decision making process using a spatial platform data, highlighting the functional relationships by attributes or spatial interactions.

The achievement of SIAD-TIGERS took place in two phases: the first phase consisted of the constitution of the geodatabase following the data model of ArcHydro, after an iterative consulting process with the stakeholders and engineers working at the agency at the conceptual step. The second phase focused on the actual implementation of the different tool in ArcGIS. ArcHydro represents one of the most achieved object-relational geodatabase framework for geospatial data and temporal support for hydrological modeling (quantity and quality) and decision-making. The second stage consisted in data collection, image acquisition, and data integration including image processing and extraction of derived products.

4.2 Geodatabase Implementation
The implementation of the database includes data collection, digitization, geoprocessing and structuring. The data is organized according to three approaches: a) thematic b) spatial and c) temporal. Thematic: The data of the project is structured into main themes: the biophysical and socio-economic profiles. Spatial: The data are integrated to ensure continuity of the analysis using different scales and spatial reference: 1) Souss-Massa whiting Morocco; 2) the watershed of the Souss-Massa 3) the sub-watersheds; Temporal: All hydrometeorological and hydrological data are available in time series. The time perspective will be used particularly for the hydrological modeling, the study of risks associated with flood and the reservoir management. Different layers of information covering bio-physical, administrative, economic and social management of the basin have been collected. The satellite images from Landsat and SPOT were purchased to develop land use. The RADARSAT images were used to prepare the terrain analysis digital elevation model, slopes, and lineaments.


Figure 1 SIAD_TIGERS conceptual framework
4.3 Updating the Spatial Information
Updating the spatial information was at the heart of the realization of SIAD_TIGERS. Decisionmaking processes on the territory and the basin environment are deficient in the Souss-Massa region. To solve the problem of spatial information availability, one of the main purposes of the implementation of SIAD_TIGERS was the development of geospatial information including the effect of changes in the land use / land cover (LULC) and the short - long term trends through the use of remote sensing images. First, radar images (RADARSAT) were used to extract digital elevation model (DEM). From these images and DEM, terrain attributes were extracted (slope, lineaments, drainage network, and so on.). These images were later used in the preparation of maps of LULC. Once this first step of establishing and updating the geodatabase was completed, a second phase consisting of the development of new information on the dynamics of the evolution of land use in the region was implemented. Image data available since 1987 and the acquisition of recent images have provided information on the state of the land use for the reference years (1987, 2002 and 2006) in order to determine the state of development and change detection in the watershed between the three marked years (87-02, 02-06, 87-06). However, this resolution (30 m) and approaches cannot meet the project objectives especially at the local level. A second approach has been implemented for the achievement of LULC on pilot areas in finer resolutions (less than 5 m). The maps at the local level were developed for three sites: a) Ouled Berhil, with insight in the expansion of irrigated land b) Irherm with insight in the evaluation of the groundwater potential c) Agadir with insight in the land monitoring in the urban area and thereafter, the interferometry study for some possible subsidence effects in urbanized areas. The maps of land for the area of Ouled Berhil cover an area of 780 km2 on a scale of the order of 1:25000. In addition, SPOT images from March 2006, September 2006 and May 2007 were also used. These multi-date maps allow a better understanding of the dynamics of uncontrolled drilling and the expansion of irrigated plots upstream of the irrigated plain. The study of LULC shows the accelerating transformation of land development since 2002 for agriculture to the detriment of the arganier forest, a classified one by UNESCO. The greenhouses, as an indicator of the intensity of agricultural production, have increased at the same time as the urbanized areas have spread in the suburban areas of Agadir. The precariousness of the availability of water in the farms located downstream encourages some farmers to move into the upstream region. Earth observation products can be used to monitor the progression of the phenomenon practically in real time with the use of multitemporal data and high resolution for 2006/2007 in areas of interest in Ouled Berhil. This new territorial knowledge enables the Agency to better enforce red zones, to challenge vested interests, and above all to better manage the territorial resources at local level.

4.4 Operational capabilities

The many issues associated with the management of water in the context of sustainable development, the complexity and scale make it a daunting task when it comes to decisionmaking. The implemented application is a way to show and experiment with the Agency the relevance and capacity of SIAD_TIGERS to deal with real problems. These applications, whenever possible, were developed with both a global and a local perspective. The applications developed a set of products providing a better understanding of the project areas relative to the availability of ground water both globally (all of Souss-Massa watershed) and locally (for Irherm); environmental vulnerability to inundation and flash flooding for the overall watershed and the local (Souss) reach at (Taroudant); dams and reservoir management (Ben Youssef TachFine (YBT) and AbdelMoumen (ABD)) and finally, erosion (overall Souss-Massa, reservoirs intake watershed). It is important to outline the various applications and how they help illustrate the potential of SIAD_TIGERS for the Agency.

4.4.1 Evaluation of Groundwater Potential

Groundwater is an alternative source of water for consumption, agriculture and recreation. The Souss Massa basin contains one of the largest aquifers in Morocco. The growth of agriculture in this region relies for a good part on the groundwater availability. However, in mountain regions, as Irherm, water is scarce; drilling realized for human consumption has known little success. The assessment of potential groundwater will enable the Agency to achieve a dual purpose. On a global level, it will have better information about the potential of the whole basin. At the local level, particularly in Irherm, supplies for the population which rely on rain water (when available) drilling using SIAD_TIGERS aim at producing maps of groundwater potential that are most conducive to the detection of confined groundwater and improving the success rate of drilling. This mapping required the pretreatment of RADARSAT-1 images to extract a map of lineaments, which has been corrected according to the information on the geological map and field data. Thereafter, an empirical model that combines the density of faults, the annual precipitation, lithology, lineaments density, land use and elevation, slope, drainage density and soil type was applied.

In general terms, the methodology has confirmed the potential of the region of the plain of the Souss. The study located in the region of Irherm enables the Agency to better focus the drilling plans in the area of more potential.


Figure 2 Ground water potential for Irherm Morocco

4.4.2 Reservoir Management

About eight reservoirs with different capacities have been erected on the territory of the Souss- Massa basin. Managers of the Agency have always been interested in seeing how the products of earth observation and geomatics could help in the management of these reservoirs for: a) a better understanding of the water flow, b) a better balance of the water stored in the reservoirs based on pre-established scenarios; and c) a better distribution of water available among the different categories of users. The implementation of this module implies interaction between hydrological and reservoir simulation models with the other data modules across SIAD_TIGERS: water level in the dam, rainfall, solar radiation, flow, and temperature.


Figure 3 YBT Reservoir simulation showing the input flow, the simulated (SIM) and the observed volume (OBS),

4.4.4 Flood Mapping

Although the region of Souss and Morocco generally evoke a sense of precariousness of water availability, it is however important to note that this region is also exposed to torrential rain and flash floods that can cause considerable damage to humans and property. Faced with the problem of protection, the question is of how best to protect the public in relation to the devastating effects of floods and flash floods through the use of integrated tools in SIAD_TIGERS. An empirical model that combines land use, elevation, slope, drainage network, distance to the drainage network, soil type and population density was applied to develop flood maps for the area. These maps were refined by flood areas from an empirical terrain study. One of these points on the river Souss at Taroudant was selected for a detailed study with hydraulic simulation. The rainfallrunoff management systems and flood alerts in SIAD_TIGERS incorporate the HEC-HMS model for hydrological forecasting, and the HEC-RAS model for hydraulic simulation.


Figure 4 Flood hazard in the Souss-Massa basin, the background image of Taroudant is from Google Earth

Conclusion
This project provides a good illustration of the relevance of the integration of knowledge, knowhow and data from earth observation, GIS, and different types of modeling tools for water management. The applications provided will improve the management and decision making in the Souss-Massa basin compared to the erosion, dam’s sedimentation, reservoir management flood and flood mapping; as well as groundwater potential in addition to tracking changes in land cover land use. This project is a good example for many other applications based on the integration of remote sensing, GIS and decision support system for the management of natural resources such as agriculture, forestry, water, soil, planning, risk management, as well as different categories of decision-making issues which many countries face.

Acknowledgements: This project was funded in part by the Canadian Space Agency. The authors thank the Souss-Massa Hydraulic Basin Agency (AHBSM) for the time series data and the Morocco Royal Center for Remote Sensing for their help in building the database and Bouma S. for the cartographic work.

References

1. Bapalu G. V. and Sinha R, 2005: GIS in flood mapping: a case study of Kosi River basin India. GISDevelopement.net, available on the Internet.
2. Musa K. A., Juhari M. A., and Abdullah I., 2000: Groundwater prediction potential zone in Langat basin using the integration of remote sensing and GIS. GISdevelopment.net, available on the Internet.