A Methodology to Assess and Evaluate Rainwater Harvesting Techniques in (Semi-) Arid Regions

Ammar Adham,Michel Riksen,Mohamed Ouessar,Coen Ritsema

doi:10.3390/w8050198

Abstract

Arid and semi-arid regions around the world face water scarcity problems due to lack of precipitation and unpredictable rainfall patterns. For thousands of years, rainwater harvesting (RWH) techniques have been applied to cope with water scarcity. Researchers have used many different methodologies for determining suitable sites and techniques for RWH. However, limited attention has been given to the evaluation of RWH structure performance. The aim of this research was to design a scientifically-based, generally applicable methodology to better evaluate the performance of existing RWH techniques in (semi-) arid regions. The methodology integrates engineering, biophysical and socio-economic criteria using the Analytical Hierarchy Process (AHP) supported by the Geographic Information System (GIS). Jessour/Tabias are the most traditional RWH techniques in the Oum Zessar watershed in south-eastern Tunisia, which were used to test this evaluation tool. Fifty-eight RWH locations (14 jessr and 44 tabia) in three main sub-catchments of the watershed were assessed and evaluated. Based on the criteria selected, more than 95% of the assessed sites received low or moderate suitability scores, with only two sites receiving high suitability scores. This integrated methodology, which is highly flexible, saves time and costs, is easy to adapt to different regions and can support designers and decision makers aiming to improve the performance of existing and new RWH sites.

Highlights

Aridity and climate change are the major challenges faced by farmers who rely on rainfed farming [1]
If the Rain Water Harvesting techniques (RWH) structures were located much closer to the watercourses, the contribution of drainage length to the overall RWH suitability would have been higher for our case study
While Al-Adamat 2008 [6], Jabr 2005 [37] and Mbilinyi 2005 [33] showed that Multi-Criteria Analysis (MCA) provides a rational, objective and non-biased method for identifying suitable RWH sites, our study demonstrates that combining MCA and expert opinion in a consistent way allows assessment and evaluation of RWH techniques beyond site selection

Summary

Introduction

Aridity and climate change are the major challenges faced by farmers who rely on rainfed farming [1]. In order to increase the availability of water for crop production and cattle grazing, inhabitants of dry areas have constructed and developed several types of Rain Water Harvesting techniques (RWH). RWH is a method for inducing, collecting, storing and conserving local surface runoff for agriculture in arid and semi-arid regions [2]. RWH and management techniques have a significant potential for improving and sustaining the rainfed agriculture in the region [4]. A wide variety of micro-catchment, macro-catchment and in situ RWH techniques are available in arid and semi-arid regions. The indigenous techniques, or those modified by the indigenous RWH practices, are more common and widely accepted by smallholder farmers than the others [5].

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Discussion

Conclusion