A principal component analysis (PCA) was used to evaluate the success of the CCME WQI as an appropriate tool to evaluate water quality data from the West Crocodile River. The CCME WQI was able to indicate the temporal and spatial water quality changes of the Krokodil West River from 1976 to 2018. water quality.
INTRODUCTION
- Background
- Problem statement
- Research aim
- Research objectives
Legislative framework for water quality management in South Africa Water resources in South Africa are managed by the Department of Water and Sanitation (DWS). However, the evaluation of the water quality of water resources from complex water quality data is still a challenge (Murugesan & Morphin-Kani, 2011). The CCME WQI records seasonal changes and historical water quality status for that water resource.
LITERATURE REVIEW
Global Legislative Framework for monitoring water quality
South African Legislative Framework for monitoring water quality
Dissemination of information on potential health risks from the microbial quality of water sources used by humans. The monitoring program measures, assesses, and regularly reports the status and trends of toxic chemical pollutants in support of strategic water resource management (Griffin et al., 2014). The program implemented the Rapid Habitat Assessment Model (RHAM) as an efficient and cost-effective method for assessing habitat conditions in aquatic resources (Griffin et al., 2014).
Selecting the water quality variables
Other sources of Cl- in water resources are irrigation return flows and industrial processes (Lowies, 2014). Oxidation of sulphide-rich pyrite ores enriches water sources with SO42- (Lowies, 2014; Mutanga & Mujuru, 2016). Suitable pH ranges for biological life in water sources are between 6 and 9 pH units (Chapman, 1996).
Water Quality Indices
A single WQI number was not sufficient to explain the water quality status of the river (Tyagi et al., 2013). Alphayo & Sharma (2018) applied the NSFWQI to determine the water quality status of the polluted Ruvu River in Tanzania. The CCME WQI records seasonal changes and the historical water quality status of the water resource.
Selection of water quality index
WQI is not a good indicator of spatial and temporal trends of water quality status. Data from several water quality variables incorporated into a mathematical equation to rank the health of water resources. The NSFWQI is strict about the criteria for the water quality variables entered into the WQI.
METHODOLOGY
- Description of Study Area
- Geology of the Crocodile-West/Marico catchment
- Topograhy of Crcodile-West/Marico catchment
- Vegetation type of Crcodile-West/Marico catchment
- Land Use of Crocodile-West/Marico catchment
- Site Selection
- Calculating CCME Water Quality Index
- Statistical analysis and representation of CCME WQI
Water quality monitoring data is outsourced from the DWS WMS database (Table 3-1). The CCME WQI was used to determine the overall water quality status of the Crocodile-West River. The CCME WQI uses water quality variables and sets targets for each water quality variable based on the purpose of the study.
RESULTS
Water Quality Trends
The figure 4-2 of the water content trend represents the seasonal concentration of K+ and Cl- from 1976 to 2018 in site 90194 of the Krokodil West River. There were spikes in concentration from site 90167 that exceeded the target water quality guideline of 0.007 mg/l NH3. There were spikes of NH3. The concentration of PO43- during this period exceeded the target water quality guideline set at 0.15 mg/l PO43-.
There were two periods when the PO43- concentration at Site 90167 exceeded the water quality guidelines (Figure 4-4). The green and dark blue lines represent the target water quality ranges as shown in Table 3-2. Water Quality Trend Figure 4-5 presents the water quality pH trend at all Crocodile-West River locations from 1976 to 2018.
Overall, pH levels at all sites changed over time between 1976 and 1980, where there was an exponential increase in pH levels at all sites.
Water Quality Index Calculations…
CCME WQI Threshold of Marginal Water Quality and Red= CCME WQI Threshold of Poor Water Quality. The calculated F3 scores for the calculated WQI ranged between 8 and 30 in years when NH3 and pH exceeded the target water quality guidelines. This indicated an increase in the number of water quality variables and the extent to which they exceeded target water quality guidelines (Table 4-2).
The Crocodile-West River was in excellent water quality status (WQI=100) in and 2011, with all water quality variables within target water quality guidelines (Figure 4-8). Phosphate, ammonia and pH failed the water quality target guidelines from 1985 to 2018, but there were exceptions. The calculated WQI marked years in which pH was the only water quality variable that exceeded the water quality guideline.
However, phosphate and pH contributed more to water quality status at site 90204 than NH3. However, NH3 and pH contributed more to water quality status at site 90233 than PO43-. Trend of the Spatial Distribution Index of Water Quality at all locations in the Crocodile River-West.
This indicated that the water quality status of the Crocodile-West River was generally good from 1976 to 2018.
Principal Component Analysis
The biplot explains the 83% variance in water quality data with a total of 66% variance explained in the first axis and 17% in the second axis. The first axis of the PCA explains the 44% variation for the differences in water quality variables and the second axis explains the 28% temporal variation of water variables. The PCA explains the 72% variance in water quality data with a total of 44% variance explained in the first axis and 28% in the second axis.
The first axis of the PCA explains the 47% variation for the differences in water quality variables and the second axis explains the 38% temporal variation of water variables (Figure 4-14). The PCA biplot explains the 86% variance in the water quality data, with a total of 47% variance explained in the first axis and 38% in the second axis. The first axis of the PCA biplot explains the 71% variation for the differences in water quality variables and the second axis explains the 16% temporal variation of water variables in site 90204 (Figure 4-15).
The PCA biplot explains 87% variance in water quality data with a total of 71% variance explained in the first axis and 16% in the second axis. The biplot explains the 74% variance in water quality data with a total of 43% variance explained in the first axis and 31% in the second axis. The PCA biplot Figure 4-17 explains the variation between the water quality variables and different locations.
The PCA biplot explains 89% variance in water quality data with a total of 75% variance explained in the first axis and 14% in the second axis.
DISCUSSION
Water Quality Trends
NH3 concentrations at site 90194 were also influenced by the currents of the Crocodile-West River. A study by Du Preez et al. 2018) showed that pH in the Crocodile-West River was affected by algal and cyanobacterial overgrowth. Electrical conductivity is an indicator of total dissolved solids (TDS) of the Crocodile-West River.
Possible sources of EC are geology and the Krokodil West River is underlain by Meinhardskraal, granite. The Krokodil West River at site 90167 is underlain by the Rashoop, Lebowa and Rustenberg geological complexes. Another source of SO42- in the Krokodil West River is from runoff containing SO42-.
The high Ca2+ concentration in the Crocodile-West River at site 90203 is related to input from the Ca-rich geology. Site 90203 of the Crocodile-West River underlies the Rooiberg geology which consists of the Transvaal sediment supergroup. Phosphate-based fertilizers applied to irrigate crops along the banks of the Crocodile-West River are sources of PO43-.
The sediments may contain Ca2+ from limestone or chalk which is calcium enrichment in the Crocodile West River (Mathebula, 2015).
Water Quality Index
There was a temporal change in water quality status for site 90167 in the Crocodile-West River. Crop cultivation activities along the Crocodile-West River were a major cause of water quality degradation in the river system (Du Preez, 2018). Agricultural and livestock activities along the Crocodile-West River were a major cause of water quality degradation in the river system (Du Preez, 2018).
Crop cultivation activities along the Crocodile-West River were a major driver of water quality change in the river system (Du Preez, 2018). The CCME WQI was excellent at indicating both the temporal and spatial water quality changes in the Crocodile-West River from 1976 to 2018. The CCME WQI was excellent at indicating the spatial changes in water quality between sites in the Crocodile-West River.
The CCME WQI indicated that the water quality status of the Crocodile-West River was generally good from 1976 to. The CCME WQI was able to detect which water quality variables exceed the target water quality guidelines for aquatic ecosystems in the Crocodile-West River. SO42- and Cl- as water quality variables that negatively affected the water quality status of the Crocodile-West River.
The study demonstrated the suitability of the CCME WQI as a tool for assessing the surface water quality of the Crocodile-West River.
Overall PCA biplot
CONCLUSIONS AND RECOMMENDATIONS
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