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Runoff water harvesting (RWH) is considered as an important tool for overcoming water scarcity in arid and semi-arid regions. The present work focuses on identifying potential RWH sites in the Wadi Watir watershed in the south-eastern part of the Sinai Peninsula. This was carried out by means of significant integration of the analytical hierarchy process (AHP), distributed spatial model, geographical information system (GIS), watershed modeling system (WMS), and remote sensing techniques (RS). This integration of modern research tools has its own bearing on the accurate identification of optimum RWH sites, which could be relied upon in developmental planning for arid environments. Eight effective RWH parameters were chosen to apply a multi-parametric decision spatial model (MPDSM), namely the overland flow distance, volume of annual flood, drainage density, maximum flow distance, infiltration number, watershed slope, watershed area and watershed length. These parameters were used within ArcGIS 10.1© as thematic layers to build a distributed hydrological spatial model. The weights and ranks of each model parameter were assigned according to their magnitude of contribution in the RWH potentiality mapping using a pairwise correlation matrix verified by calculating the consistency ratio (CR), which governs the reliability of the model application. The CR value was found to be less than 0.1 (0.069), indicating acceptable consistency and validity for use. The resulting MPDSM map classified the watershed into five categories of RWH potential, ranging from very low to very high. The high and very high classes, which are the most suitable for RWH structures, make up approximately 33.24% of the total watershed area. Accordingly, four retention dams and seven ground cisterns (tanks) were proposed in these areas to collect and store the runoff water, whereby these proposed RWH structures were chosen according to the soil type and current land-use pattern. The resulting MPDSM map was validated using a topographic wetness index (TWI) map, created for the watershed. This integrative and applied approach is an important technique which can be applied in similar arid environments elsewhere.

The scarcity of water in the Campo de Cartagena has limited its exploitation, which is why, historically, runoff water has been used through sustainable traditional practices which have been dismissed by technological advances. In order to demonstrate the potential of this resource at present, an analysis by interpolation of rainfall distribution in the sub-basin of the Rambla de Fuente Álamo-Albujón was carried out (for the intense rainfall episodes of 2012 and 2016) as well as hydraulic modelling of the estimation of surface runoff. In addition, taking into account the future climate scenarios, a projection of the total runoff in the study area was made up to the year 2100. The bibliographic review and the press analysis showed that the traditional use of runoff water has remained in disuse, although there are infrastructures to collect water from floods but with an eminently sanitary purpose. The current model of agricultural and touristic exploitation is giving rise to serious socio-environmental conflicts which manifest in obsolescence. Therefore, the increase in the availability of water with the use of a specific endogenous resource may lead to a decrease in the pressures exerted on the study area. La escasez hídrica del Campo de Cartagena ha limitado su explotación, por ello, históricamente, se han aprovechado las aguas de escorrentía mediante prácticas tradicionales sostenibles que han sido desterradas por los avances tecnológicos. Con el propósito de demostrar el potencial de este recurso en la actualidad, se ha llevado a cabo (para los episodios pluvimétricos intensos de 2012 y 2016), un análisis por interpolación de la distribución de precipitaciones en la subcuenca de la Rambla de Fuente Álamo-Albujón, así como una modelización hidráulica de la estimación de la escorrentía superficial. Además, atendiendo a los escenarios climáticos futuros, se ha realizado una proyección de la escorrentía total en el área de estudio hasta el año 2100. La revision bibliográfica y el análisis de prensa ha puesto de manifiesto que el aprovechamiento tradicional de las escorrentías ha quedado en desuso aunque existen infraestructuras de captación de arroyadas pero con una finalidad eminentemente sanitaria. El modelo actual de explotación agrícola y túristica está dando lugar a conflictos socioambientales graves que manifiestan su obsolescencia por lo que el aumento de la disponibilidad de agua con el aprovechamiento de un recurso endógeno puntual, supondría una disminución de las presiones ejercidas sobre el área de estudio.