**Table 3.** Unintended impacts of the upgrading process related to good (black) and poor (red) operation, allocated to spheres of influences.


#### *3.6. Scenario Analysis* initial income (R3). Besides the willingness to pay, the fodder demand depends on the

As described above, the two main drivers of the water reuse system comprise management and fodder demand. Figure 4 shows a causal loop diagram of the various system components linked with the identified drivers. The diagram combines the three categories, ecology, society and economy, with the system of water reuse for fodder production. The causal links between the variables are represented by arrows with a positive or negative polarity indicating the type of influence. Furthermore, the diagram shows reinforcing (R) and balancing feedbacks (B), feedbacks consisting of at least two variables forming a loop. need for fodder, which in turn relies on the number of livestock and natural pastures. These two variables also form a balancing feedback as they are directly connected to two causal links of different polarity (B). The same applies to the variables asset and number of livestock, but due to the two positive causal links there is a reinforcing feedback here (R4). By combining R3 and R4 with the need for fodder, a new reinforcing feedback is created (R5). Furthermore, different existing loops can be merged, e.g., the combination of R1 and R5 with health risks and population leads to the reinforcing feedback R6.

quality, in turn, indicates a positive causal link with the quality of the fodder, which generates income. As a result of the yields achieved from the sale of fodder, the management is again strengthened, which completes the reinforcing effect (R1). Another reinforcing feedback arises from the causal links of the management to pond overflowing and from there to the contamination. Contamination is linked to the soil quality and therefore to the fodder. Similar to R1, fodder generates income, which in turn leads to initial management. Since this loop comprises two negative causal links, a reinforcing feedback is formed (R2). Additional reinforcing feedback concerns income, since income from fodder creates an increase in assets in all their facets. Therefore, the willingness to pay for fodder and also fodder demand rises due to the positive causal links, resulting in

*Water* **2022**, *14*, x FOR PEER REVIEW 17 of 23

**Figure 4.** Causal loop diagram of the different system components linked with the main driving forces, management and fodder demand (highlighted). Two strokes on a causal link symbolize a time delay between the current and perceived state of a process. Blue circles containing either an R or a B represent reinforcing or balancing feedbacks. **Figure 4.** Causal loop diagram of the different system components linked with the main driving forces, management and fodder demand (highlighted). Two strokes on a causal link symbolize a time delay between the current and perceived state of a process. Blue circles containing either an R or a B represent reinforcing or balancing feedbacks.

By identifying the feedbacks, the complexity of the water reuse system in relation to the driving forces becomes clear. The diagram facilitates the assessment of the four identified scenarios A1 (good management and high fodder demand), A2 (bad management and high fodder demand), B1 (good management and low fodder demand) and B2 (bad management and low fodder demand). Since a scenario analysis similar to the CLD model developed would be difficult to cope with and numerous overlaps occur in the content of the scenarios, the focus of the evaluation is on highlighting the differences in order to avoid repetition of impacts. Figure 5 shows the intended and unintended impacts of the upgrading and assigns them to the four scenarios. If effects only apply to one single scenario, they are located in one of the four corners. In addition, there are four fields in which two scenarios demon-The most important reinforcing feedback consists, among others, of the variables management and water quality, which are connected by a positive causal link. Water quality, in turn, indicates a positive causal link with the quality of the fodder, which generates income. As a result of the yields achieved from the sale of fodder, the management is again strengthened, which completes the reinforcing effect (R1). Another reinforcing feedback arises from the causal links of the management to pond overflowing and from there to the contamination. Contamination is linked to the soil quality and therefore to the fodder. Similar to R1, fodder generates income, which in turn leads to initial management. Since this loop comprises two negative causal links, a reinforcing feedback is formed (R2). Additional reinforcing feedback concerns income, since income from fodder creates an increase in assets in all their facets. Therefore, the willingness to pay for fodder and also fodder demand rises due to the positive causal links, resulting in initial income (R3). Besides the willingness to pay, the fodder demand depends on the need for fodder, which in turn relies on the number of livestock and natural pastures. These two variables also form a balancing feedback as they are directly connected to two causal links of different polarity (B). The same applies to the variables asset and number of livestock, but due to the two positive causal links there is a reinforcing feedback here (R4). By combining R3 and R4 with the need for fodder, a new reinforcing feedback is created (R5). Furthermore, different existing loops can be merged, e.g., the combination of R1 and R5 with health risks and population leads to the reinforcing feedback R6.

By identifying the feedbacks, the complexity of the water reuse system in relation to the driving forces becomes clear. The diagram facilitates the assessment of the four identified scenarios A1 (good management and high fodder demand), A2 (bad management and high fodder demand), B1 (good management and low fodder demand) and B2 (bad management and low fodder demand). Since a scenario analysis similar to the CLD model developed would be difficult to cope with and numerous overlaps occur in the content of the scenarios, the focus of the evaluation is on highlighting the differences in order to avoid repetition of impacts. *Water* **2022**, *14*, x FOR PEER REVIEW 18 of 23

> Figure 5 shows the intended and unintended impacts of the upgrading and assigns them to the four scenarios. If effects only apply to one single scenario, they are located in one of the four corners. In addition, there are four fields in which two scenarios demonstrate the same characteristics of a single driving force, for example, a high fodder demand in the upper middle. The ninth and last field in the middle contains impacts that can occur in all four scenarios. strate the same characteristics of a single driving force, for example, a high fodder demand in the upper middle. The ninth and last field in the middle contains impacts that can occur in all four scenarios.


**Figure 5.** Ecological (green), social (orange) and economic impacts (blue) of the upgrading process associated with the four identified scenarios; corner fields represent impacts that occur only for the specific scenario; middle outer fields symbolise overlaps between two adjacent scenarios with the same driving force, and the field at the centre overlaps of all four scenarios. **Figure 5.** Ecological (green), social (orange) and economic impacts (blue) of the upgrading process associated with the four identified scenarios; corner fields represent impacts that occur only for the specific scenario; middle outer fields symbolise overlaps between two adjacent scenarios with the same driving force, and the field at the centre overlaps of all four scenarios.

Effects that occur in all four scenarios include only unintended impacts, namely, the displacement of wildlife, the risk of ponds overflowing during heavy rainfall, a possible burden on the operator and the fact that women do not benefit from fodder production and pastoralism. In addition, overgrazing is already widespread in northern Namibia. On the one hand, additional fodder could relieve the strain on natural resources. On the other hand, pastoralists would prefer free grass to produced fodder. Another effect that can always occur independently of the driving forces is brain drain, especially if there Effects that occur in all four scenarios include only unintended impacts, namely, the displacement of wildlife, the risk of ponds overflowing during heavy rainfall, a possible burden on the operator and the fact that women do not benefit from fodder production and pastoralism. In addition, overgrazing is already widespread in northern Namibia. On the one hand, additional fodder could relieve the strain on natural resources. On the other hand, pastoralists would prefer free grass to produced fodder. Another effect that can always occur independently of the driving forces is brain drain, especially if there are wage payment bottlenecks.

are wage payment bottlenecks. Irrespective of the fodder demand, good management leads to relief of the WSP and less repair work for the plant. Furthermore, reusing water relieves the strain on natural resources. With good management, the effluent is characterised by a good water Irrespective of the fodder demand, good management leads to relief of the WSP and less repair work for the plant. Furthermore, reusing water relieves the strain on natural resources. With good management, the effluent is characterised by a good water quality, which benefits fodder production with nutrients and a minimised risk of contamination,

quality, which benefits fodder production with nutrients and a minimised risk of con-

nas is significantly lower than before the upgrade. Society also benefits from the management through improved hygiene and income associated with employment. Addi-

the involvement and education of the population can lead to a lack of acceptance.

In contrast, bad management leads to maintenance issues and thus a lower quality of water. Therefore, an increased risk of land contamination is present, in particular by heavy metals, resulting in lower product quality and health risks for consumers. In addition, the lower water quality and the particles contained in the water lead to pipe blockages and damage to the pipes. With an insufficient management, the risk of ponds overflowing and therefore the risk of contaminating the Oshanas also increases. Concerning society, information inequalities can widen the social divide. In addition, a disregard for

tionally, good management reduces emissions and odour nuisance.

thereby improving soil fertility. Good management also reduces the risk of ponds overflowing, and in the event of heavy rain, the strain on the surrounding Oshanas is significantly lower than before the upgrade. Society also benefits from the management through improved hygiene and income associated with employment. Additionally, good management reduces emissions and odour nuisance.

In contrast, bad management leads to maintenance issues and thus a lower quality of water. Therefore, an increased risk of land contamination is present, in particular by heavy metals, resulting in lower product quality and health risks for consumers. In addition, the lower water quality and the particles contained in the water lead to pipe blockages and damage to the pipes. With an insufficient management, the risk of ponds overflowing and therefore the risk of contaminating the Oshanas also increases. Concerning society, information inequalities can widen the social divide. In addition, a disregard for the involvement and education of the population can lead to a lack of acceptance.

Assuming that fodder production is guaranteed regardless of the management style, high fodder demand is associated with revenues for the operators. The consideration of a high demand for fodder shows that the number of livestock will increase due to the avoidance of emergency slaughtering. As a result, the increased number of animals will lead to increased methane emissions and overgrazing of natural pastures.

Less fodder demand, however, results in issues with revenues and thus the maintenance of the system. In addition, benefits from marketing and trade are missing out. A low fodder demand based on a lack of willingness to pay or financial resources does not change the state of emergency slaughtering, resulting in losses for pastoralists. Furthermore, a lack of yield by farmers can lead them to reconsider their cultivation system and possibly generate higher margin products that do not meet water quality standards. Otherwise, a complete reorientation towards water reuse alternatives could be initiated.

Concerning the scenario-related impacts, it is noticeable that the number of such effects is relatively small. A dominant factor is the generated yields for fodder and the associated revenues for the operator, which vary from scenario to scenario. In the worst-case scenario (B2), inadequate management coupled with low demand for fodder will generate the lowest yields. In this case, the operation of the underlying system consisting of water treatment and fodder production would not make sense. In terms of yields, this is similar in scenario B1, where there is good management and thus good water quality, but low fodder demand is the basis. If these circumstances do not change in the near future, it would be advisable to rethink this kind of water reuse, as the efforts extend beyond the benefits.

The situation is different in the case of inadequate management combined with high demand for fodder (A2), where income is generated from the yields. However, due to the lower product quality coupled with possible crop losses, the yields to be achieved are lower. Here, more conscious management could significantly increase yields and thus incomes. Optimal conditions are given in scenario A1, where good management meets high fodder demand. This is where the highest yields are achieved, which benefits the operators themselves and the maintenance of the system. As a prestige object, this would enhance the reputation of the operator and the town. At the same time, in terms of transferability, the concept thus represents a prime example for other regions.

#### **4. Conclusions**

Against the background of the current problems in managing WSP systems and water supply constraints in central northern Namibia, this study demonstrated that water reuse based on an upgrade of WSPs represents an extremely sensible and sustainable concept. The impact assessment has shown that intended positive impacts clearly outweigh the unintended ones. Wastewater is not only disposed, but is seen as a new water resource. Thus, a polluting liquid is transformed into a value benefitting the population and the ecosystem. In addition, the concept reveals a new opportunity for water reuse and constitutes a major advantage for water supply and relief regarding limited water resources. The relatively new approach of the SEIA has proven useful and insightful in assessing

the social–ecological impacts of the water reuse system and the corresponding success factors and hazards of the transformation process. In this way, insights for a long-term enhancement of living and ecosystem conditions could be achieved.

Following conclusions can be drawn:


**Author Contributions:** M.Z. and F.N. conceived and designed the study; F.N. conducted and analyzed the interviews and wrote large parts of the paper; M.Z. wrote additional parts of the paper and made the final edits; M.Z. contributed to the acquisition of funds, administered and supervised the project. All authors have read and agreed to the published version of the manuscript.

**Funding:** The project was funded by the German Federal Ministry of Education and Research (BMBF) under the funding measure WavE (funding code 02WAV1401B). Open access fees were covered by the BMBF Post Grant Fund (funding code 16PGF0371).

**Institutional Review Board Statement:** The study was conducted in accordance with the Declaration of Helsinki, and approved by the Ethics Commission of the ISOE–Institute for Social-Ecological Research, Frankfurt am Main, Germany (2022).

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Acknowledgments:** The authors would like to thank all Namibian and German interview partners together with the German project partners, in particular, the institute IWAR of the Technical University in Darmstadt. The article was written as part of the project 'EPoNa—Upgrading wastewater pond systems to generate irrigation water for animal fodder production using the example of Outapi, Namibia'.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

