Developing Decision Support System (DSS) for Integrated Water Resources Management (IWRM)

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1 Department of Water Resources Studies Success Stories: Developing Decision Support System (DSS) for Integrated Water Resources Management (IWRM) The situation of the water supply in the Arab region is characterized by water scarcity and, at the same time, by increasing demand caused by population growth as well as expanding economy and agriculture. Furthermore, climate change models predict for the coming years even more severe conditions in the water sector, associated with rising temperatures and decreasing precipitation. The decision makers have to respond to the most urgent questions: How will the water balance change in time and which action is required to achieve a sustainable water supply? A Decision Support System (DSS), based on computational models, renders assistance in this complex issue. In the framework of a technical cooperation project with the Arab Center for the Studies of Arid Zones and Dry Lands (ACSAD) a DSS has been developed, which mainly consists of two components: the water evaluation and planning software WEAP (Water Evaluation And Planning System), developed by the Stockholm Environment Institute (SEI) ( and the 3-D groundwater flow model MODFLOW, developed by the U. S. Geological Survey (USGS). Elements of water demand (cities, industry, irrigation, environment...) and water resources (precipitation, rivers, groundwater, reservoirs, desalinization plants...) are depicted and combined in the WEAP schematic. WEAP calculates the water balance on different scales - in each element up to the whole catchment. Additionally, aspects of cost and quality can be considered. The future development of the water balance can easily be simulated by the scenario manager, taking into account socio-economic conditions and climate change. The linkage with MODFLOW enables a spatially and temporally discritized prediction of groundwater tables, flows and storage, which is of special interest in arid and semi arid regions.

2 In two pilot areas, Zabadani Basin, Syria, and Berrechid Basin, Morocco, the DSS was tested and applied. These applications proved the strengths of the DSS tool especially considering the impacts of climate change, changes in demand and supply, waste water reuse and artificial recharge scenarios on water availability. The DSS has been giving the local stakeholders, institutions and decision makers a valuable base for their current and future water management planning. Zabadni Basin The Zabadani Basin is located in the Antilebanon Mountains covering an area of about 140 km². The basin is drained by the only perennial stream of the region, the Barada River, which has its source at the Barada Spring at 1095 m a.s.l. The mean annual rainfall is about 700 mm. About people living permanently in the area, however during summer especially in Zabadani and Bloudan the population doubles or triples by the number of tourists. There is already a water competition in the area between drinking water suppliers of the area, Damascus water supply authority and agricultural and touristic activities. In dry years Barada Spring (average discharge 3.8 m³/s) ceases completely during the summer months, raising conflicts between the farmers relying on the river discharge and the Damascus City Water Supply and Sewerage Authority (DAWSSA), which is operating a major well field next to Barada Spring. Since the very beginning of the project a steering committee has been set up, integrating all the relevant stakeholders into the DSS development, data acquisition and future scenario planning. By the linked WEAP-MODFLOW models realistic soil-, groundwater balances and hydraulic heads for the reference year 2004/ 2005 could be calculated and the results can be visualized by WEAP in various scales from the total area down to the subcatchment and its land use class levels. For the Barada Spring the yearly discharge was computed correctly, however the monthly fluctuation due to the karstic nature and rapid and slow flow components couldn t be matched exactly.

3 Figure 4 30: 3D view of the computed groundwater surface. By the linked WEAP-MODFLOW models realistic soil-, groundwater balances and hydraulic heads for the reference year 2004/ 2005 was calculated and the results can be visualized by WEAP in various scales from the total area down to the sub catchment and its land use class levels. Two sets of scenarios have been calculated by the DSS, a historic scenario ( ) in order to check the calibration accuracy of the models and a planning scenario set ( ) of three different climate/demand change scenarios. Berrechid Basin The Berrechid Basin is located just south of Casablanca, Morocco between the Atlantic Ocean and the Phosphate Plateau. The total area is about 1500 km². Geomorphologic ally it is a flat basin with elevations of 140 m a.s.l. in the north and about 350 m a.s.l. at the southern margin at the Settat Plateau. The topographic gradient doesn t exceed 0.2 % except at the southern margin where it can increase to 0.8%. It is a tectonic basin with subsidence and sedimentation since the Triassic. Due to the basin s fertile soil and great groundwater potential, the agricultural development and also the irrigated areas increased significantly during the past years, growing mainly vegetables, fodder crops and fruit trees. Overexploitation of the aquifer caused a regional groundwater drawdown of about ten meters in the centre of the basin, dry wells and reduced productivity of the wells in the area.

4 The reference scenario modelled correctly the increases in domestic and irrigation demands. Irrigation is the largest fraction of the water uses.the increased demands has been satisfied by increased groundwater abstractions leading to a severe decrease in groundwater storage and declining water levels. The DSS-results of the historic and future scenarios showed the current status of groundwater overuse and possible action plans for the future (Figure). The DSS can be a valuable planning tool to understand the current situation and to decide on the best planning scenario for the future to manage the groundwater resource in a sustainable way. Figure: Hydraulic head decline between 1980 and 2004 The DSS was introduced and applied by the basin agency as a pilot study to test and evaluate the capabilities of it as a water management tool. With a yearly time step and the rough yearly input parameters or estimations (calibrated to match the MODFLOW inputs) the general trends could be modelled and respective results visualized. The ministry and also the other basin agencies have been showing large interest on the DSS-tool and in two national training workshops in February and April 2008 this tool has been introduced to additional basin agencies. There is also a large interest to use a common national method/ tool (which could be the WEAP/MODFLOW-DSS) to calculate water balances on a basin level, which will be then integrated into a national

5 water master plan. Therefore DSS will soon prove its strengths and capabilities on basin and on national levels. Dissemination The systemwas distributed among the ACSAD member countries through: Organizing training courses (table 1) for techniciansin Jordan, Lebanon, Syria, Morocco, Tunisia and Palestine on this system as a good tool for the integrated water resources management, and to adapt toclimate change. Table 1: Dissemination of ACSAD s experiences in WEAP. Organizing tworegional Conferences on Applying WEAP as a Decision Support System for IWRM, first one in Syria, 2009 in, SYRIA and second one in Jordan, 2012to present theachievementsoftheprojectand callingfor the deployment oftechniquesdevelopedinthearabworld.

6 The results of the project have been published in a lot of journals, books, reports and conferences. Most of the documents can be downloaded from this link: b_en.html?nn= DSS improvement The WEAP-MODFLOW Decision Support System has been improved continuously. Several add-in models were developed through this project: MODFLOW: Ground Water modeling MABIA: the model simulates transpiration, evaporation, irrigation requirements and scheduling, crop growth and yields. It also includes modules for estimating reference evapotranspiration and soil water capacity All Water Optimization: Optimization of abstraction rates and pumping allocation MODPATH: 3d particle tracking model