Physicochemical characterization and applicability of the mini stream assessment scoring system and the South African scoring system version 5 in the Upper Awash Basin, Ethiopia.

Abstract

The Sustainable Development Goal (SDG) 6, introduced by the United Nations in 2015, focus on ensuring the availability and sustainable management of water, also encompassing the quality and sustainability of freshwater resources. Central to achieving SDG 6 is target 6.3, which aims to improve water quality by 2030. An essential indicator for this goal is SDG 6.3.2, tracking the proportion of water bodies with good ambient water quality. SDG 6.3.2 requires monitoring programmes based on relevant and measurable parameters. However, Africa faces challenges in implementing conventional physico-chemical water quality monitoring due to limitations such as scarce testing facilities, resource constraints, and expensive logistics. Therefore, a complementary approach is needed and in the context of this study, Biomonitoring is regarded as a necessary strategy. Biomonitoring involves assessing river health using aquatic macroinvertebrates. Research indicates successful applications of Biomonitoring in various countries, particularly in South Africa, where Biomonitoring tools like the South African Scoring System version 5 (SASS5) and the simplified Stream Assessment Scoring System (miniSASS) have been developed, tested and used. SASS5 is a standardized method that evaluates the presence and richness of macroinvertebrates, acting as sensitive indicators of water quality. MiniSASS is designed for non-experts, supports citizen science initiatives and aligns with SDG 6. b. The study aims to test the applicability of SASS5 and miniSASS in intermittent rivers and ephemeral streams in the Upper Awash River in Ethiopia. This region, situated in the Ethiopian highlands, represents a tropical area with high biodiversity and prominent water quality challenges. The research site choice is strategic, considering tropical rivers and more especially intermittent rivers and ephemeral streams which are often overlooked in water quality assessments. The study employs both Biomonitoring and physicochemical monitoring, including heavy metals. Principal Component Analysis (PCA) results highlight an inverse correlation between Biomonitoring metrics and heavy metals. The clustering of heavy metals in opposite end of the cluster of Biomonitoring scores reveals that Biomonitoring could be a good index for water quality even in relation of pollution with heavy metals. This research contributes to advancing scientific knowledge and addresses the applicability of South African Biomonitoring tools in diverse environmental contexts beyond their country of origin.