scholarly journals AREAL REDUCTION FACTORS FOR DESIGN RAINFALL ESTIMATION IN THE MODDER-RIET RIVER BASIN, SOUTH AFRICA

2019 ◽  
Author(s):  
JACOBUS P. J. PIETERSEN ◽  
OCKERT J. GERICKE
Keyword(s):  
South Africa ◽  
River Basin ◽  
Rainfall Estimation ◽  
Design Rainfall ◽  
Reduction Factors

scholarly journals Disaggregation of fixed time interval rainfall to continuous measured rainfall for the purpose of design rainfall estimation

Water SA ◽  
2018 ◽  
Vol 44 (4 October) ◽  
Author(s):  
OJ Gericke ◽  
JPJ Pietersen
Keyword(s):  
South Africa ◽  
Fixed Time ◽  
Estimation Methods ◽  
Time Interval ◽  
Rainfall Estimation ◽  
Fixed Time Interval ◽  
Design Rainfall ◽  
Thiessen Polygon ◽  
Continuous Measures

Design rainfall estimates are primarily used in single-event deterministic design flood estimation methods where estimates of the peak discharge are based on the critical storm duration or time of concentration (TC) of a catchment. Therefore, daily design rainfall depths used in flood estimations must either be decreased or increased from durations less than or longer than 24 hours to the design rainfall depths for a rainfall duration of TC. This paper presents the comparison of two South African methods used to convert or scale 1-day fixed time interval observed rainfall (08:00 to 08:00) to continuous measures of n-hour rainfall for selected TC durations at a quaternary catchment level, in the C5 secondary drainage region in South Africa as pilot case study. In each quaternary catchment, the annual maximum series (AMS) of the 1-day fixed time interval point rainfall were extracted, infilled, converted and scaled to appropriate continuous measures of TC-hour point rainfall using conversion factors (Adamson, 1981) and scaling factors (Smithers and Schulze, 2003), respectively. Thereafter, all the TC-hour observed point rainfall values were averaged to observed catchment rainfall at a quaternary catchment level using the Thiessen polygon method. In using the two methods to estimate continuous short-duration n-hour (TC ≤ 24 hours) and long-duration n-hour (TC > 24 hours) catchment rainfall from 1-day fixed time interval point rainfall, an acceptable (0.71 < r2 ≤ 0.86) and high (r2 ≥ 0.93) degree of association were achieved, respectively, despite the different approaches used in each method. Overall, the results confirmed that fixed time interval rainfall should be scaled to continuous measures of rainfall using the Smithers-Schulze scale invariance approach for various TC durations in the case study area. In comparison to the Adamson conversion methodology, the Smithers-Schulze scaling methodology is also based on a more extensive and recent rainfall database as incorporated in software for design rainfall estimation in modern flood hydrology practice in South Africa.

Enhancing Water Security through Restoration and Maintenance of Ecological Infrastructure:  Lessons From the uMngeni River Basin, South Africa

2021 ◽  
Author(s):  
Graham Jewitt ◽  
Catherine Sutherland ◽  
Sabine Stuart-Hill ◽  
Jim Taylor ◽  
Susan Risko ◽  
...  
Keyword(s):  
South Africa ◽  
Human Capital ◽  
River Basin ◽  
Green Infrastructure ◽  
Natural Capital ◽  
Critical Role ◽  
Water Security ◽  
Constitutive Relationship ◽  
Ecological Infrastructure ◽  
Sustainable Water Supply

&lt;p&gt;The uMngeni River Basin supports over six million people, providing water to South Africa&amp;#8217;s third largest regional economy. A critical question facing stakeholders is how to sustain and enhance water security in the catchment for its inhabitants. The role of Ecological Infrastructure (EI) (the South African term for a suite of Nature Based Solutions and Green Infrastructure projects) in enhancing and sustaining water and sanitation delivery in the catchment has been the focus of a project that has explored the conceptual and philosophical basis for investing in EI over the past five years.&lt;/p&gt;&lt;p&gt;The overall aim of this project was to identify where and how investment into the protection and/or restoration of EI can be made to produce long-term and sustainable returns in terms of water security assurance. In short, the project aimed to guide catchment managers when deciding &amp;#8220;what to do&amp;#8221; in the catchment to secure a more sustainable water supply, and where it should be done. This seemingly simple question encompasses complexity in time and space, and reveals the connections between different biophysical, social, political, economic and governance systems in the catchment.&lt;/p&gt;&lt;p&gt;Through the study, we highlight that there is an interdependent and co-constitutive relationship between EI, society, and water security. In particular, by working in spaces where EI investment is taking place, it is evident that socio-economic, environmental and political relations in the catchment play a critical role in making EI investment possible, or not possible.&lt;/p&gt;&lt;p&gt;The study inherently addresses aspects of water quantity and quality, economics, societal interactions, and the governance of natural resources. It highlights that ensuring the availability and sustainable management of water resources requires both transdisciplinary and detailed biophysical, economic, social and development studies of both formal and informal socio-ecological systems, and that investing in human resources capacity to support these studies, is critical. In contrast to many projects which have identified this complexity, here, we move beyond identification and actively explore and explain these interactions and have synthesised these into ten lessons based on these experiences and analyses.&lt;/p&gt;&lt;ul&gt;&lt;li&gt;1 - People (human capital), the societies in which they live (societal capital), the constructed environment (built capital), and natural capital interact with, and shape each other&lt;/li&gt; &lt;li&gt;2 - Investing in Ecological Infrastructure enhances catchment water security&lt;/li&gt; &lt;li&gt;3 - Investing in Ecological Infrastructure or BuiIt/Grey infrastructure is not a binary choice&lt;/li&gt; &lt;li&gt;4 - Investing in Ecological Infrastructure is financially beneficial&lt;/li&gt; &lt;li&gt;5 - Understanding history, legacy and path dependencies is critical to shift thinking&lt;/li&gt; &lt;li&gt;6 - Understanding the governance system is fundamental&lt;/li&gt; &lt;li&gt;7 - Meaningful participatory processes are the key to transformation&lt;/li&gt; &lt;li&gt;8 - To be sustainable, investments in infrastructure need a concomitant investment in social and human capital&lt;/li&gt; &lt;li&gt;9 - Social learning, building transdisciplinarity and transformation takes time and effort&lt;/li&gt; &lt;li&gt;10 - Students provide new insights, bring energy and are multipliers&lt;/li&gt; &lt;/ul&gt;

Bioaccumulation and trophic transfer of total mercury in the subtropical Olifants River Basin, South Africa

Chemosphere ◽  
2019 ◽  
Vol 216 ◽  
pp. 832-843 ◽  
Author(s):  
Vera Verhaert ◽  
Johannes Teuchies ◽  
Wynand Vlok ◽  
Victor Wepener ◽  
Abraham Addo-Bediako ◽  
...  
Keyword(s):  
South Africa ◽  
River Basin ◽  
Total Mercury ◽  
Trophic Transfer ◽  
Olifants River

Interdependent effects of climate variability and forest cover change on streamflow dynamics: a case study in the Upper Umvoti River Basin, South Africa

2019 ◽  
Vol 19 (7) ◽  
pp. 1963-1971
Author(s):  
Karen Lebek ◽  
Cornelius Senf ◽  
David Frantz ◽  
José A. F. Monteiro ◽  
Tobias Krueger
Keyword(s):  
South Africa ◽  
Climate Variability ◽  
River Basin ◽  
Forest Cover ◽  
Forest Cover Change
Sign in / Sign up

Export Citation Format

Share Document