## 2 Materials and Methods
### Data Collection
#### 2.3.2 Performance Assessment  
* \(\bullet\) Conveyance efficiency  
Performance assessment was also for both the off-field and infield components. When water passes through the system, every component of the system causes a head loss, which in turn influences efficiency of delivery. In addition, water loss through leakages also affects water delivery efficiency. The off-field components were assessed for water delivery. Therefore, water flow (\(Q\), m\({}^{3}\)/s) in pipes constituting the delivery systems between main pumps at boreholes and manifolds at edges of the irrigated lands was measured using an ultrasonic flow transducer (FLEXIM GmbH, Berlin, Germany). The measurements were performed during normal irrigation operating periods when water was running in the pipes. The transducer was calibrated for pipe size, material, fluid type, and temperature before measurements could be performed. Flow measurement was performed at the inlet (inflow) and outlet (outflow) of each component, and the difference between the inflow and outflow constituted a water loss. Conveyance efficiency (\(CE_{i}\)) was the preferred flow performance index and was computed using the equation:  
\[CE_{i}=100\frac{Q_{in}-Q_{out}}{Q_{in}} \tag{1}\]  
where \(CE_{i}\) = conveyance efficiency (%) for the \(i\)th component; \(Q_{in}\) and \(Q_{out}\) = inflow and outflow rates (m\({}^{3}\)/s), respectively. The overall conveyance efficiency (\(CE\)) at each Agri-Park was computed as the product of the conveyance efficiencies for the system components. * Distribution uniformity  
In addition to head losses, energy loss in the water flowing through pipes also influences the variation of discharge, for example, from the first to the last emitter of a system [3]. Head loss was not investigated in the current study. Drip emitter discharge (\(q_{e}\), L h\({}^{-1}\)) was \begin{table}
\begin{tabular}{l l l l} \hline
**Scale** & **Linguistic Scale** & **Criteria** & **Action Needed** \\ \hline
9–10 & Excellent & Newly/recently installed. & No action required. \\ \hline
8–9 & Very good &
\begin{tabular}{l} Like new with no signs of \\ corrosion or deterioration. \\ \end{tabular} & Reassess in 15 years. \\ \hline
6–8 & Good & \
\begin{tabular}{l} Coatings, linings still intact. \\ Remaining wall thickness more \\ than 90\% of original. \\ \end{tabular} &
\begin{tabular}{l} Reassess in 10 years. \\ Schedule for cathodic \\ protection within next \\ 5–10 years. \\ \end{tabular} \\ \hline
4–6 & Moderate & \
\begin{tabular}{l} Some damage to coatings \\ and/or linings noted. Remaining \\ wall thickness 75\% or more \\ of original. \\ \end{tabular} &
\begin{tabular}{l} Reassess in 3–5 years. \\ Schedule for lining and \\ rehabilitation within next \\ 5–10 years. \\ \end{tabular} \\ \hline
3–4 & Poor & \
\begin{tabular}{l} Significant signs of \\ internal/external corrosion. \\ Collapse inevitable. No lining \\ or coatings. Leaking. Remaining \\ wall thickness 50–75\% \\ of original. \\ \end{tabular} &
\begin{tabular}{l} Schedule for rehabilitation \\ or replacement within next \\ 3–5 years. \\ \end{tabular} \\ \hline
3–5 & Critical & \
\begin{tabular}{l} Severe internal or external \\ corrosion. \\ Collapse evident. Large \\ cracks/holes. \\ Remaining wall thickness less \\ than 50\% of original. Breakage \\ rate \textgreater{} 3. \\ \end{tabular} &
\begin{tabular}{l} Immediate repair or \\ replacement required. \\ \end{tabular} \\ \hline \end{tabular}
\end{table} 
Table 1: Condition scores used to rate the irrigation infrastructure at the Agri-Parks, Gauteng province (adopted from [23]). measured at five positions on each of three selected drip lines (Figure 2).