Sustainable agriculture can be defined as the integration of environmental, social, and economic components to secure society’s food needs [1
]. Achieving food security in the face of global population growth requires that sustainable agricultural productivity be enhanced [1
]. In arid and semi-arid regions of the world, which are home to a significant proportion of the population, water resource availability is a key factor in sustainable agriculture [2
]; and uncertain water supply in many countries can threaten sustainable development [5
]. This makes agriculture the major water-demanding sector in the world [6
] and means that sustainable agricultural development is challenging, especially in regions where increasing water scarcity and lack of sustainable water resource management are prevailing [8
]. As a result, the dominant water resource management challenge is how to satisfy the increasing agricultural water demand in order to enhance food security for the rapidly expanding world population [9
In Palestine, which is characterized as an arid to semi-arid region, the lack of sufficient water for different uses has constrained sustainable development [10
]. The situation has worsened due to population growth and the associated expansion of agricultural activities, imposing a remarkable burden on the limited available and uncertain water supply (e.g., groundwater). Moreover, without a doubt, the on-ground political conflict is also affecting the availability and/or accessibility of Palestinian water resources [11
Agricultural water poverty (AWP) is a term that describes both quantitative and qualitative shortages in existing agricultural water resources [2
]. It can be attributed to natural or human-induced causes [13
]. AWP can be estimated by using the agricultural water poverty index (AWPI), which is an index that describes sustainable agricultural water management at farm-level [2
]. AWPI can be affected by several factors, including availability of agricultural water, water quality and suitability for agricultural use, access to agricultural water resources and efficiency of use of supplied agricultural water [1
], all of which impact food production.
Water poverty mapping is an easy and effective way to map, for instance, the spatial distribution of agricultural water-poor areas [15
]. Worldwide, water poverty mapping is commonly used to evaluate both domestic and agricultural water vulnerabilities [15
]. The use of water poverty mapping can be valuable for developing strategies to enhance water resource management and sustainable agricultural development.
Generally, agricultural water-poor areas have to consider new and/or unconventional and sustainable sources of water. In arid and semi-arid regions, given the uncertain water supply, rainwater harvesting (RWH) can be used to safeguard water for different uses [19
]. This in turn has the potential to improve the social, environmental, and economic development of an area [20
]. In the West Bank, RWH is considered a strategic alternative to satisfy the increasing water supply–demand gap for both domestic and agricultural uses [22
]. RWH can be defined in many ways; however, there is not a unified definition about this term that is commonly accepted by the scientific community. Researchers employ a wide variety of terms and definitions to describe the various methods aimed at the use of, collection, and storage of rain runoff in order to increase the availability of water for drinking, irrigation, and so on, in arid and semi-arid areas. In this way, their criterion is their own purpose and not a strict definition of the term “rainwater harvesting” [23
]. It is considered an ancient practice, and is still used for domestic and agricultural purposes all over the world, particularly in arid and semi-arid regions [24
In these regions, agricultural water productivity has been improved by implementing proper RWH techniques for many years [2
]. From this, the concept of agricultural rainwater harvesting (ARWH) has developed, where the focus is to collect and use rainwater specifically to increase crop yields [3
]. Depending on the efficiency of the RWH technique, ARWH can be used either to enhance soil moisture content mainly in rainfed areas (e.g., the use of terraces) or as a source of water for supplementary irrigation when there is a shortage of agricultural water supply (e.g., the use of small dams to collect runoff) [24
]. Accordingly, agricultural rainwater harvesting suitability (ARWHS) is an approach to identify potential locations where the implementation of ARWH techniques would be possible and effective.
To date, studies have mainly looked at the suitability of locations for new RWH structures, without consideration of water poverty. Adding water poverty mapping and promoting RWH and ARWH in regions where the benefits are expected to be high, based on water poverty (e.g., where water is the limiting production factor), has the potential to improve implementation of these strategies. This paper presents an approach to combining the mapping of ARWHS and AWP in order to increase the successful implementation of RWH. This new method for RWH site selection was developed and has been applied to the West Bank (Palestine) using a GIS-based multi-criteria decision analysis (MCDA) integrated approach. The MCDA approach is commonly used in both water poverty mapping [15
] and RWH suitability studies [18
], as further explained in the next section. This research will be of interest to policy makers and other potential stakeholders to identify areas where ARWH can be most effective for increasing sustainable agricultural development and food security in the West Bank, Palestine.
The aim of this research is to better identify locations for successful implementation of ARWH techniques. As such, the used approach was to combine the identification of locations with high to very high agricultural water shortage with suitability mapping for RWH. Research findings show that 61% of the total West Bank is classified as high to very high agriculture water-poor areas. The ARWHS map indicates that high to very high suitable areas are concentrated in the north-western parts of the West Bank, with some small areas that are located in the middle and southern parts. The high to very high AWP and ARWHS areas formed more than 40% of the West Bank. Moreover, 53% of the rough grazing areas (62% of the entire West Bank area) are characterized as high to very high ARWH-suitable areas.
GIS-based MCDA was utilized for the mapping of AWP and ARWHS for the case study of the West Bank, Palestine. This approach is of high value to identify the suitable sites where the implementation of proper ARWH techniques is deem to be a strategic option to enhance water availability for agricultural uses, mainly in high agricultural water-poor areas. The MCDA approach was utilized to study the importance of influencing criteria (layers) in the mapping of AWP and ARWHS. Normalized weights were assigned for different layers using the AHP pairwise comparison matrix approach. The combined mapping used in this research can be applied elsewhere once the thematic layers (criteria) become available. Further, it helps identify potential sites where the implementation of ARWH techniques can successfully satisfy water needs, especially in agricultural water-poor areas.
However, the used approach has some shortcomings. The accuracy of the obtained maps is greatly dependent on the resolution and ground alterations of the used thematic GIS layers, and the subjectivity and judgment in assigning the scores of the different input layers (criteria). The social, economic, and environmental limitations were not studied. Despite of these drawbacks, we think that our novel approach managed to provide insight toward the identification, by means of the AWP map, of high agricultural water-poor areas with a high potential for successful implementation of ARWH techniques based on the ARWHS map.
In view of the fact that the MCDA entails subjectivity in assigning the weights and the scores of different input layers, it is recommended that an uncertainty assessment be conducted by altering the weights and scores and, thereafter, the impacts on the mapping of both AWP and ARWHS be assessed. Further research is recommended to identify proper sites based on site selection criteria (including social, economic, and environmental) analysis for a realistic implementation of proper ARWH techniques in the West Bank to best support the social, economic, and environmental aspirations of the Palestinians.
To conclude, the results of this research study can be used by key policy makers (PWA and MoA) and other potential stakeholders to prioritize areas where ARWH can be most effective to improve sustainable agricultural development and food security in the West Bank, Palestine.