scholarly journals Water quality modelling of an impacted semi-arid catchment using flow data from the WEAP model

Author(s):  
Andrew R. Slaughter ◽  
Sukhmani K. Mantel

Abstract. The continuous decline in water quality in many regions is forcing a shift from quantity-based water resources management to a greater emphasis on water quality management. Water quality models can act as invaluable tools as they facilitate a conceptual understanding of processes affecting water quality and can be used to investigate the water quality consequences of management scenarios. In South Africa, the Water Quality Systems Assessment Model (WQSAM) was developed as a management-focussed water quality model that is relatively simple to be able to utilise the small amount of available observed data. Importantly, WQSAM explicitly links to systems (yield) models routinely used in water resources management in South Africa by using their flow output to drive water quality simulations. Although WQSAM has been shown to be able to represent the variability of water quality in South African rivers, its focus on management from a South African perspective limits its use to within southern African regions for which specific systems model setups exist. Facilitating the use of WQSAM within catchments outside of southern Africa and within catchments for which these systems model setups to not exist would require WQSAM to be able to link to a simple-to-use and internationally-applied systems model. One such systems model is the Water Evaluation and Planning (WEAP) model, which incorporates a rainfall-runoff component (natural hydrology), and reservoir storage, return flows and abstractions (systems modelling), but within which water quality modelling facilities are rudimentary. The aims of the current study were therefore to: (1) adapt the WQSAM model to be able to use as input the flow outputs of the WEAP model and; (2) provide an initial assessment of how successful this linkage was by application of the WEAP and WQSAM models to the Buffalo River for historical conditions; a small, semi-arid and impacted catchment in the Eastern Cape of South Africa. The simulations of the two models were compared to the available observed data, with the initial focus within WQSAM on a simulation of instream total dissolved solids (TDS) and nutrient concentrations. The WEAP model was able to adequately simulate flow in the Buffalo River catchment, with consideration of human inputs and outputs. WQSAM was adapted to successfully take as input the flow output of the WEAP model, and the simulations of nutrients by WQSAM provided a good representation of the variability of observed nutrient concentrations in the catchment. This study showed that the WQSAM model is able to accept flow inputs from the WEAP model, and that this approach is able to provide satisfactory estimates of both flow and water quality for a small, semi-arid and impacted catchment. It is hoped that this research will encourage the application of WQSAM to an increased number of catchments within southern Africa and beyond.

2020 ◽  
Vol 163 (3) ◽  
pp. 1247-1266 ◽  
Author(s):  
Hagen Koch ◽  
Ana Lígia Chaves Silva ◽  
Stefan Liersch ◽  
José Roberto Gonçalves de Azevedo ◽  
Fred Fokko Hattermann

AbstractSemi-arid regions are known for erratic precipitation patterns with significant effects on the hydrological cycle and water resources availability. High temporal and spatial variation in precipitation causes large variability in runoff over short durations. Due to low soil water storage capacity, base flow is often missing and rivers fall dry for long periods. Because of its climatic characteristics, the semi-arid north-eastern region of Brazil is prone to droughts. To counter these, reservoirs were built to ensure water supply during dry months. This paper describes problems and solutions when calibrating and validating the eco-hydrological model SWIM for semi-arid regions on the example of the Pajeú watershed in north-eastern Brazil. The model was calibrated to river discharge data before the year 1983, with no or little effects of water management, applying a simple and an enhanced approach. Uncertainties result mainly from the meteorological data and observed river discharges. After model calibration water management was included in the simulations. Observed and simulated reservoir volumes and river discharges are compared. The calibrated and validated models were used to simulate the impacts of climate change on hydrological processes and water resources management using data of two representative concentration pathways (RCP) and five earth system models (ESM). The differences in changes in natural and managed mean discharges are negligible (< 5%) under RCP8.5 but notable (> 5%) under RCP2.6 for the ESM ensemble mean. In semi-arid catchments, the enhanced approach should be preferred, because in addition to discharge, a second variable, here evapotranspiration, is considered for model validation.


2007 ◽  
Vol 4 (5) ◽  
pp. 3793-3837 ◽  
Author(s):  
V. M. Kongo ◽  
J. R. Kosgei ◽  
G. P. W. Jewitt ◽  
S. A. Lorentz

Abstract. The establishment of a catchment monitoring network is a process, from the inception of the idea to its implementation, the latter being the construction of relevant gauging structures and installation of the various instruments. It is useful that the local communities and other stakeholders are involved and participate in such a process as was realised during the establishment of the hydrological monitoring network in the Potshini catchment in the Bergville district in the KwaZulu-Natal Province in South Africa. The paper illustrates the participatory application of various methods and techniques for establishing a hydrological monitoring network, in a small rural inhabited catchment, to monitor hydrological processes at both field and catchment scale for research purposes in water resources management. The authors conclude that the participation of the local community and other stakeholders in catchment monitoring and instilling the sense of ownership and management of natural resources to the local communities needs to be encouraged at all times. Success stories in water resources management by local communities can be realized if such a process is integrated with other development plans in the catchment at all forums with due recognition of the social dynamics of the communities living in the catchment.


2010 ◽  
Vol 14 (12) ◽  
pp. 2507-2525 ◽  
Author(s):  
V. M. Kongo ◽  
J. R. Kosgei ◽  
G. P. W. Jewitt ◽  
S. A. Lorentz

Abstract. The establishment of a catchment monitoring network is a process, from the inception of the idea to its implementation, the latter being the construction of relevant gauging structures and installation of the various instruments. It is useful that the local communities and other stakeholders are involved and participate in such a process, as was highlighted during the establishment of the hydrological monitoring network in the Potshini catchment in Bergville District in the KwaZulu-Natal Province, South Africa. The paper highlights the participatory establishment of a hydrological monitoring network in a small rural inhabited catchment, in line with the overall objective of the Smallholder System Innovations (SSI) research programme, to monitor hydrological processes at both field and catchment scale for water resources management research purposes. The engagement and participation of the Potshini community precipitated a learning opportunity for both the researchers and the local community on (i) the understanding of hydrological processes inherent in the catchment (ii) appreciating the inherent dynamics in establishing a catchment monitoring network in the midst of a community (iii) paradigm shift on how to engage different stakeholders at different levels of participation. The participatory engagement in the monitoring process led to appreciation and uptake of some of the research results by the Potshini community and ensured continued support from all stakeholders. This paper is of the view that the participation of the local community and other stakeholders in catchment monitoring and instilling a sense of ownership and management of natural resources to the local communities needs to be encouraged at all times. Success stories in water resources management by local communities can be realized if such a process is integrated with other development plans in the catchment at all forums, with due recognition of the social dynamics of the communities living in the catchment.


2001 ◽  
Vol 43 (4) ◽  
pp. 155-163 ◽  
Author(s):  
A. R. Turton ◽  
B. Schreiner ◽  
J. Leestemaker

The Dublin Principles recognize the role that women play in water resources management. The South African Minister of Water Affairs, Prof. Kader Asmal, coined a new expression by referring to the “feminization of water”. The article explores some of the ramifications of this and shows that the two aspects are not necessarily the same thing. Feminization does not necessarily mean bringing more women into management processes as it is often depicted. This is the quantitative aspect that is often referred to by male managers and it has been given a negative implication as a result. The more important issue is the qualitative aspect that involves processes such as stakeholder participation, viewing alternatives before a decision is made and accountability.


1995 ◽  
Vol 32 (5-6) ◽  
pp. 293-299
Author(s):  
H. M. MacKay ◽  
D. J. Roux ◽  
P. J. Ashton ◽  
H. R. van Vliet ◽  
S. Jooste

This paper describes the progress made by the Department of Water Affairs and Forestry in the development of documented water quality guidelines for aquatic ecosystems in South Africa, which will be able to take into account local and site-specific conditions. Proposed guidelines for toxic substances, nutrients and physico-chemical variables are described.


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