Understanding the hydrology of a Swati peatland: A case study of Malolotja Nature Reserve, Eswatini

Abstract

<div> <p><span>The Malolotja Nature Reserve is located on the great southern African escarpment which comprises the ecotone between the highveld and middleveld. The reserve has several streams, rivers and wetlands with the most significant being the Malolotja wetland which, during a reconnaissance undertaken in 2018, showed it to contain significant peat deposits. This is the first scientific record of peatlands within the country. While it is widely acknowledged that the primary characteristic of peatlands is their high organic content, their ability to retain water and therefore their hydrological properties, control their existence and development. The first hydrology of the peatland was investigated using a network of 10 wells, 18 piezometers and 1 rain gauge; installed in one transect at specific monitoring points within the peat. Monitoring of various hydrological parameters was initiated on April 14th, 2019 and ceased on May 31st, 2020. Monitoring of water levels, electrical conductivity, water temperature, rainfall and air temperature was conducted weekly.</span><span> </span></p> </div><div> <p><span>The findings suggest that the northern and central areas of the peatland have a shallow water table, high electrical conductivity and low water temperatures, while the peripheral areas have a deeper water table, lower electrical conductivity and higher water temperatures. The dominant water sources for the peatland appear to be rainfall, groundwater, recharge from the central stream back into the peat, and slope seepage. The peatland also appears to be a good sink for ammonium, with a pH range varying from slightly acidic to slightly basic. Without a detailed mineralogical study of the underlying bedrock, a geological contribution (though appearing unlikely) cannot be completely verified out. It is in this context that further analysis of the peat itself is currently underway, and it is hoped that this will provide a better understanding of how water moves within the system</span><span>.</span><span> </span></p> </div>