Rainfall and flow variations in the Lesotho Highlands

Abstract

The Lesotho Highlands contain some of the highest mountains in southern Africa and play an important role in the surface water resources of the region. Several features of the climatology and hydrology of the highlands are reviewed here. The emphasis is on the long‐term response and the behaviour on an annual basis. Topics discussed include the variations in rainfall with elevation and location, the relationships between annual rainfall and river flows, and the variations over time in both rainfall and flow records. Results are presented in the form of updated versions of the mean annual precipitation and mean runoff coefficient maps for the region, and examples are presented for typical regression relationships between flows and rainfall data on an annual basis. Also, statistical analyses are described that suggest little evidence for any significant cyclical behaviour or trend during the observational periods for either rainfall or flow data. © 1998 Royal Meteorological Society

Some attributes of snow occurrence and snowmelt/sublimation rates in the Lesotho Highlands: environmental implications

“…800 to 1 500 mm·y -1 (Sene et al, 1998;Nel and Sumner, 2008), but apparently exceeds evaporation (Zunckel, 2003).…”

“…Although most (80%) contemporary precipitation occurs between October and April (Tyson, 1986;Sene et al, 1998), most snowfalls occur in mid-winter (June and July). It is estimated that between 5 and 10 contemporary snowfalls occur over the Lesotho Highlands per annum (Tyson et al, 1976;Mulder and Grab, 2002), yet the water equivalent is estimated at less than 100 mm/annum (Nel and Sumner, 2005).…”

Fine-Scale Variations of Near-Surface-Temperature Lapse Rates in the High Drakensberg Escarpment, South Africa: Environmental Implications

“…1). The high escarpment zone is an important ''water tower'' in southern Africa, where annual precipitation (estimated between 800 and 1500 mm yr ‫1מ‬ ; Sene et al, 1998;Nel and Sumner, 2008) exceeds evaporation (Zunckel, 2003). Floristically, the high Drakensberg escarpment belongs to the Drakensberg Alpine Centre (DAC), a composite of high-altitude (Ͼ1700 m a.s.l.)…”

“…Although several studies have discussed climate attributes such as air flow (Freiman et al, 1998), precipitation (Sene et al, 1998;Sumner, 2005, 2008) and temperatures (Killick, 1978a;Grab, 1997;Nel and Sumner, 2008) for the Drakensberg escarpment, there are no published records on fine-scale temperature lapse rates and how these might vary within distinct altitudinal zones and on opposing slope aspects (northeast vs. southeast) as one approaches the escarpment summit. Equally, it would appear that little, if any, work has focused on surface temperature lapse rates for other major global escarpments such as the Serra do Mar (Brazil), Western Ghats and Deccan Traps (India), Great Escarpment of eastern Australia, and Simien Mountain escarpment (Ethiopia).…”

“A sky of brass and burning winds”: documentary evidence of rainfall variability in the Kingdom of Lesotho, Southern Africa, 1824–1900

“…One such area is the topographically diverse kingdom of Lesotho (Fig. 1), which has a distinct tropical mountain climate (Sene et al 1998). The systematic collection of meteorological data in Lesotho started in Maseru, Mafeteng and Leribe in 1886 and was extended to other settlements from 1892 onwards.…”