CHAPTER 4 RESULTS AND DISCUSSION
4.3 Results from questionnaire (quantitative and qualitative) analysis
4.3.2 Section B: Background on irrigation practices
4.3.2.2 Crops under irrigation
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of key drivers of and risks posed by the water quality and will be important in the discussions in sections 4.3.4 and 4.3.5.
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Farmers were asked to elaborate on the land area under irrigation in each of the crop categories for the year 2000 and 2020 (QB6F and QB7F). The intention behind the inclusion of this detail was to determine whether there was any significant change in crop type over the past 20 years.
The size of the average land area where grapes were cultivated per farm were 100 ha with the maximum size being 1 000 ha for a mega-farm where several smaller farms were amalgamated.
The average land area where fruit were cultivated was below 100 ha. The land size where mixed farming (pastures and diaries) dominate, ranged between 100 ha and 500 ha. There was no significant change reported in the distribution of crop type on the available land area over the past 20 years. The main change was where additional land was purchased or land not previously utilised was added to the total land area cultivated. This was generally considered to be due to the fact that the area investigated was an already established farming area with most available fertile/ usable land (already) cultivated by 2000. It was therefore not possible to make comparisons between the different years and between the sections of the Breede River. The results for crop under irrigation confirm the description of agricultural activities in the BGWMA indicated by previous studies which suggested that irrigation in the Middle Breede River was dominated by vineyards (Murray, Biesenbach and Badenhorst Inc. 1989; DWAF, 2003). However, there has been expansion in the land area where citrus is cultivated and changes in crop from grape to citrus in the Middle Breede River section seen in recent years.
Farmers were asked to indicate the volume of water used for irrigation (m3/year) (QB8F) and to elaborate on any restrictions on irrigation water volume allocated over the past 20 years (QB5E/QB13F). The quantity of irrigation water used for crop production, all exceeded 50 000 m3/year (Figure 4-27). The majority of Farmers indicated that the minimum volume of water required for irrigation was between 6 000 m3/ha/year and 12 000 m3/year depending on the crop type. It was not possible to give a detailed breakdown per crop type from their records; therefore a simple multiplication of the land area (ha) with the average of 7 000 m3/ha/year was used to provide a breakdown per crop type across the catchment.
The participants were asked an open-ended question to elaborate on occurrences of and reason(s) for allowance restrictions on water for irrigation purposes in the Breede River catchment between the year 2000 and 2020 (QB5E/QB13F). The thematic analysis of their responses yielded themes which were then identified as the main causes for restrictions in irrigation water allocations. The main themes included:
Flow restrictions during summer months;
Flow restrictions during droughts;
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Increased surface storage reduces flow; and
Re-allocation and user conflicts.
(a) (b)
(c)
Figure 4-27: Distribution of the average volume of water for irrigation purposes used in (a) grape, (b) fruit and (c) other (including pasture) irrigation along the Breede River
(QB8F).
Most Farmers irrigating from the Breede River indicated that during late summer and periodic droughts the volume of water available for irrigation was affected. Comments included: “During late summer the river flow is low, in last drought even dried-up but no restrictions on allocations - could still use full quota but when river dried-up there was a period of 3 weeks when no irrigation was possible” (F13), and “During late summer most streams dry-up (Oct-March)” (E10). Farmers dependent on irrigation canals indicated that during severe droughts the allocated water was cut
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by up to 60%. Most Farmers indicated that where water was abstracted from the Breede River, abstraction continued until no flow in the river was left. This was also linked to water quality concerns as commented by F6: “Maintenance cost related to cleaning irrigation system and filter due to algae/ silt clogging the system”, and F7: “Lower water volume during drought brings changes in water quality”. Information on the allocation restrictions experienced is important as this can influence the perceptions of water quality since water quality during low flow periods would differ significantly from high flow (flushing) periods. The Experts group agreed that water allocation restrictions occurred during droughts as highlighted by E5 which indicated that: “In general in 10 year cycles on average 3 years are lower rainfall years where water used for irrigation is restricted”.
Most Farmers indicated they abstract their allocated volume during the wet winter months and store these in farm dams for use later in the dry summer season as the majority of crops require year round irrigation. The majority of crops require the highest volume of irrigation during the dry summer period. However, a shift in the crop types in the future was highlighted to have the potential to impact irrigation scheduling and availability throughout the year. This has been identified as a potential water availability concern as commented by F7: “stream modifications channelling mountain stream water into farm dams whereby lower lying farms are not receiving natural flow from streams anymore”. A shift in the period when the allocated volume will be abstracted in future will have an impact on irrigation and water security in the entire Breede River catchment. Experts indicated that there has been an increase in the applications for new dams or the expansion of existing irrigation dams (in-stream and off-channel dams) on farms to increase water security after the recent (2018) prolonged drought. Many Farmers indicated that during prolonged droughts they make use of ground water as emergency supply for irrigation purposes.
Farmers were asked to indicate the amount of fertilizer as well as herbicides and pesticides used for production in irrigated crops between 2000 and 2020 (QB14F and QB15F). Most Farmers could not provide detailed values for agro-chemical use per year during this period from their records but provided an estimated total. In most instances Farmers indicated that they moved away from granular fertilizer applied in a blanket/ general ton per hectare irrespective of the plants’
needs in 2000 to either liquid or dissolvable agro-chemicals that can be applied through the irrigation system in 2020 (Figure 4-28). These systems use less agro-chemicals due to a change in the irrigation system from overhead or flood irrigation to micro and drip irrigation over the years.
Micro and drip irrigation uses less water and is directed at the plant stem and roots, thereby limiting the amount of agro-chemical products used. The intention behind the inclusion of this detail was to determine the contribution of agriculture to the pollution load in the surface streams.
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However, since Farmers could not provide details on the quantity of agro-chemicals used the results of this section is not considered accurate enough to quantify the proportion of pollution load contributed by the agricultural sector.
(a) (b)
Figure 4-28: Distribution of quantity of fertilizer (ton) used in irrigated crops for (a) 2000 and (b) 2020 (QB14F).