Drought: A Common Environmental Disaster

Droughts have been identified as an environmental hazard by environmentalists, ecologists, hydrologists, meteorologists, geologists, and agricultural experts. Droughts are characterised by a decrease in precipitation over a lengthy period, such as a season or a year, and can occur in virtually all climatic zones, including both high and low rainfall locations. This study reviewed drought-related impacts on the environment and other components particularly, in South Africa. Several attempts have been made using innovative technology such as earth observation and climate information as recorded in studies. Findings show that the country is naturally water deficient, which adds to the climate fluctuation with the average annual rainfall in South Africa being far below the global average of 860 mm per year. Drought in South Africa’s Western Cape Province, for example, has resulted in employment losses in the province’s agriculture sector. According to the third quarterly labor force survey from 2017, the agricultural industry lost almost 25,000 jobs across the country. In the Western Cape province, about 20,000 of these were lost which has a direct impact on income generation. Many of these impacts were linked to drought events.

Download Full-text

Rainfall and river flow trends for the Western Cape Province, South Africa

South African Journal of Science ◽

10.17159/sajs.2019/6028 ◽

2019 ◽

Vol 115 (9/10) ◽

Cited By ~ 1

Author(s):

Rakhee Lakhraj-Govender ◽

Stefan W. Grab

Keyword(s):

Climate Change ◽

South Africa ◽

River Flow ◽

Supply And Demand ◽

Temporal Distribution ◽

Annual Rainfall ◽

Western Cape ◽

Western Cape Province ◽

Winter Rainfall ◽

Intergovernmental Panel

Climate change has the potential to alter the spatio-temporal distribution of rainfall, subsequently affecting the supply and demand of water resources. In a water-stressed country such as South Africa, this effect has significant consequences. To this end, we investigated annual and winter rainfall and river flow trends for the Western Cape Province over two periods: 1987–2017 and 1960–2017. Annual rainfall for the most recent 30-year period shows decreasing trends, with the largest magnitude of decrease at the SA Astronomical Observatory rainfall station (-54.38 mm/decade). With the exception of the significant decreasing winter rainfall trend at Langewens (-34.88 mm/decade), the trends vary between stations for the period 1960–2017. For the period 1987–2017, statistically significant decreasing winter trends were found at four of the seven stations, and range from -6.8 mm/decade at Cape Columbine to -34.88 mm/decade at Langewens. Similarly, the magnitudes of decreasing winter river flow at Bree@Ceres and Berg@Franschoek are greater for the more recent 30-year period than for 1960–2017. Correlation coefficients for Vilij@Voeliv rainfall and four river flow stations Berg@Franschoek, Bree@Ceres, Wit River@Drosterkloof and Little Berg@Nieuwkloof) are stronger for shorter periods (i.e. 1987–2017 and 2007–2017) than that for the longer period, 1960–2017. The Intergovernmental Panel on Climate Change emphasises the importance of studies to assist with model prediction uncertainties. To this end, our study expands the understanding of regional hydrological responses to rainfall change in the water stressed region of the Western Cape Province.

Download Full-text

Extent of Soil Acidity in No-Tillage Systems in the Western Cape Province of South Africa

Land ◽

10.3390/land9100361 ◽

2020 ◽

Vol 9 (10) ◽

pp. 361

Author(s):

Adriaan Liebenberg ◽

John Richard (Ruan) van der Nest ◽

Ailsa G. Hardie ◽

Johan Labuschagne ◽

Pieter Andreas Swanepoel

Keyword(s):

South Africa ◽

Crop Production ◽

Acid Soils ◽

Soil Survey ◽

Annual Rainfall ◽

Western Cape ◽

No Tillage ◽

Western Cape Province ◽

Tillage Systems ◽

Depth Increment

Roughly 90% of farmers in the Western Cape Province of South Africa have converted to no-tillage systems to improve the efficiency of crop production. Implementation of no-tillage restricts the mixing of soil amendments, such as limestone, into soil. Stratification of nutrients and pH is expected. A soil survey was conducted to determine the extent and geographical spread of acid soils and pH stratification throughout the Western Cape. Soil samples (n = 653) were taken at three depths (0–5, 5–15, 15–30 cm) from no-tillage fields. Differential responses (p ≤ 0.05) between the two regions (Swartland and southern Cape), as well as soil depth, and annual rainfall influenced (p ≤ 0.05) exchangeable acidity, Ca and Mg, pH(KCl), and acid saturation. A large portion (19.3%) of soils (specifically in the Swartland region) had at least one depth increment with pH(KCl) ≤ 5.0, which is suboptimal for wheat (Triticum aestivum), barley (Hordeum vulgare), and canola (Brassica napus). Acid saturation in the 5–15 cm depth increment in the Swartland was above the 8% threshold for production of most crops. Acid soils are a significant threat to crop production in the region and needs tactical agronomic intervention (e.g. strategic tillage) to ensure sustainability.

Download Full-text