The Elephant Marsh, Malawi – Part 1: reconstruction of the historic hydromorphology

Abstract

The Elephant Marsh lies on the floodplain of the lower Shire River, in southern Malawi. It is both a cultivated, seasonal floodplain and an area of permanent shallow lakes. The marsh is highly biodiverse, has a productive fishery and supports the livelihoods of a large human population. Chronicles and hand-drawn sketches by 19th-century explorers and subsequent travellers describing the marsh landscape were used to develop an account of the marsh’s historic hydromorphology. These anecdotal accounts are supported by Shire River outflows from Lake Malawi, inferred from observed water levels in the lake from c. 1900. Records show that the marsh has experienced regular periods of drying out, followed by periods of greater inundation than it currently experiences. Long-term hydrological trends have been accompanied by anthropogenic influences such as catchment degradation and embankment construction, which have altered sedimentation patterns in the marsh. The marsh exhibits traits of resilience to natural long-term climate change through its ability to return to a similar state during wet periods, even following prolonged dry periods. Over relatively short time frames, however, the ecology of the marsh, as described when it was declared a RAMSAR site in 2017, likely has low resistance to hydrological regimes that are sensitive to climate change. An appreciation of long-term climate and recent human-induced changes afforded a unique opportunity for contextualising its hydromorphological trends within the Anthropocene.