Statistical Analysis of Relationships Between the Flow Regime and Riverine Ecosystems in the Umba River, Kenya

Abstract

The Umba River basin is a transboundary river catchment shared between Kenya and Tanzania. It is endowed with unique and endemic plant and animal species in the coastal area. The river flow plays important role in maintaining the estuary that provides essential functions and services to the communities living in the area. To protect the freshwater biodiversity and to maintain the essential goods and services provided by the river, the components of the natural flow regime need to be investigated. The statistical analyses of relationships between the flow regime and the riverine ecosystems were evaluated using Ecosystem Functions Model (EFM). A natural flow regime composed of daily time series of water levels and discharges was analysed. Based on the flow regime and eco-hydro relationships, several statistical and seasonal results were computed for five ecosystem groups: aquatic animals, mangrove plants, riparian vegetation, macro invertebrates, and floodplain wetlands. The seasonal results presented the performance of the ecosystem groups in each water year of the flow period and the statistical results were computed as stages, flows, and percent exceedance for each relationship. The findings of this study can be considered as baseline information for comparing and identifying effective water resources development projects in the river.

Keywords: Estuary, flow regime, HEC-EFM, riverine ecosystems, Umba River