I bet that almost all policy and decision-makers have a direct or indirect investment portfolio. Most investment portfolios are diversified across a variety of stocks and bonds to minimise risk, to preserve capital and generate returns. Diversification is a well-established mechanism to protect a portfolio from volatility to the same events. In addition, a smart investment portfolio has a long-term game plan, it is continually interrogated and adjusted when required. Modern portfolio theory (MPT) suggests that "… an investment's risk and return characteristics should not be viewed alone but should be evaluated by how the investment affects the overall portfolio's risk and return".

In the water context, climate change, lower rainfall, population growth, economic expansion, storage depletion (like siltation of dams), over- allocation, pollution and so forth creates volatility in the water supply portfolio. You have probably worked out where I am going with this analogy.

The primary input to our water resources is rainwater and the rainfall is unevenly distributed in time and space. A recent WRC study confirmed that 10% of our water source areas provides 50% of the mean annual runoff. Combined with climatic patterns, topography, the spatial distribution of population and industries, South Africa is inherently a water scarce country. This is worsened by an increasing shift towards overall lower rainfall and higher evapotranspiration in southern Africa. Surface storage systems consist of about 4,395 registered dams, 3,601 of these are small dams serving mainly agriculture and municipalities. The few low capacity desalinisation plants (brackish groundwater and seawater) are localised. Groundwater is widely but unevenly distributed, owing to the complexity of our geology. Groundwater is predominantly used in agriculture, rural water supply and some urban supply – Tshwane uses between 8-13% groundwater from springs.

Mitigating against water scarcity Source water supply planning and development must be diversified to mitigate against water scarcity — a serious threat to South Africa’s water security. UN-Water defines water security as, “The capacity of a population to safeguard sustainable access to adequate quantities of acceptable quality water for sustaining livelihoods, human well-being, and socioeconomic development, for ensuring protection against water- borne pollution and water-related disasters, and for preserving ecosystems in a climate of peace and political stability". By borrowing concepts from the investment sciences, we can build a narrative, and tactical plan to diversify our source water supply portfolio for different scales and contexts. Our water supply options must consist of a mix of surface water reservoirs, groundwater aquifers, seawater, rainwater harvesting, stormwater harvesting, fog water harvesting, direct and indirect wastewater reuse and so forth.

There is even evidence to suggest that harvesting break-off icebergs and cloud-seeding can provide additional water under periods of severe water scarcity. Traditionally, South Africa had a source water portfolio that consisted mainly of surface water reservoirs and some groundwater.

This goes against having a diversified portfolio that can mitigate against water shortages. All of its investments and institutional configurations serviced mainly surface water systems — a bubble was created; another economic term we are all too familiar with. 98% of our available surface water has been allocated and if you add to that the complexities of climate and weather variability and water losses among others it is easy to predict the future challenges.

On a broad scale, it seems that South Africa is fairly well-covered concerning water supply options. However, large parts of the country are water insecure. Water insecurity can be grouped under availability, access and usage. If you interrogate water security plans it becomes clear that it deals mainly with bulk water supply options and not smaller decentralised systems. Water security can be experienced at the household to catchment level. As an example, groundwater provides >5 % of the water supply to 36% of all settlements in South Africa. A large proportion of the 36% relies 100% on groundwater. Although a small proportion of the overall water system, groundwater provides 100% water security for large parts of the country where surface water source networks are not available.

Serving the unconnected However, if you look at the investments and institutional support for this resource, it becomes clear that water security in not the main driver when we plan. Large investments are made for bulk water systems with the assumption that it reaches most of the population. In the main, it provides water security for urban areas linked to these bulk systems. It is estimated, in the National Water and Sanitation Master Plan (NWSMP), that by 2025 that there will be small increases in groundwater supply and the incorporation of acid mine drainage water into the supply mix.

Desalinisation will also increase marginally as a percentage of the total water supply. The bulk of the desalinisation will come from coastal seawater units. Several desalinisation plants are already operational in Kwa-Zulu Natal, Eastern and Western Cape. Similarly, the All Towns studies promote mostly two options. No sense is given about how the unconnected will be served, the mostly already under-served rural areas.

There needs to be a paradigm shift in our planning and how we assess water supply needs and the options available in all settings to ensure water security for all. Again, we can borrow a concept from MPT called the efficient frontier. The efficient frontier allows investors to understand how a portfolio's expected returns vary with the amount of risk taken – considering the various options (split between bonds and stocks). The investment combinations that make up the portfolio determines the overall returns. Here the risk can be construed as accessibility to the resource, energy requirements, infrastructure investments and availability, topography, assurance of supply, water quality and so forth. Based on these, a suitable combination of source water supply options can be developed into a water supply mix that can be managed conjunctively and is locality relevant. Any good savings plan has passive income or has defensive investments – in there we can create a portfolio with demand-side interventions such as behaviour change, water efficient devices, reducing water losses, efficient agro-practices, pricing strategies, managed aquifer recharge, improved storage and enforcement of bylaws and regulations.

Hydro-amnesia Jurisdictions that diversified its source water supply coupled with demand-side interventions are generally more water secure than areas relying on a single supply source. When a single supply source is under threat decision-makers scramble to diversify its supply. What is strange though is that once the source that was yielding poor returns starts recovering there is a move away from the diversification strategy – and planners and decision-makers experience hydro-amnesia until the next supply shortage. I bet that they would not allow this to happen to their personal investment portfolios. The administrator or investment consultant will probably get the boot.

ABOUT THE AUTHOR Dr Shafick Adams is an executive manager at the Water Research Commission.

Historically, the risk of electricity supply failure did not play a significant role in the design and operation of water-supply and distribution systems. In 2010, the introduction of load shedding prompted the (WRC) to initiate a high-level study of the effect of electricity interruptions on water supply. A follow-up study, which was recently concluded, explored the implications of such in greater detail and took account of new concerns that have arisen.

The study used and was based on the preparedness of the Tshwane Municipality, which makes up a significant portion of the Rand Water supply area. Some 80% of the municipality’s water supply is derived from Rand Water and Magalies Water while the remaining portion is derived from the city’s own sources at Rietvlei Dam, Roodeplaat Dam along with various dolomitic springs and wells.

The study made use of risk analysis methods and selection was based on a quantitative approach and the duration and likelihood of the various hazards identified were estimated based on the available information. The likelihood of the worst-case scenario (total black out for 30 days) was found to be highly improbable (1: 155-year probability). However, the other scenarios highlighted that there is a lack of or no preparedness of key water supply infrastructure points at the Municipal level. Water will stop flowing if there is an extended loss of electricity. Further the scenario analyses provided the following insights:

• For short-term electricity disruption events: It is crucial to ensure (firstly) that reservoirs and elevated towers are large enough to be able to supply at least two days’ annual average daily demand (AADD). Secondly, reservoirs and towers’ operating rules should be adhered to in order to ensure that water levels are maintained within the fluctuation volume of the reservoirs/towers.

Supporting sustainable development through research funding, knowledge creation and dissemination

• For medium- to long-term electricity disruption events: The volume of water stored is less important since the water stored in reservoirs will almost certainly run out of water is not supplied into the reservoir.

• Backup power generations (both mobile and permanent) will require ongoing servicing and maintenance – this will have to be incorporated into the city’s water department’s operational and maintenance schedules.

• Providing emergency storage capacity for sewerage inflow in wastewater treatment works is more expensive than providing backup power generation at wastewater treatment works. Emergency storage will not be practical for medium- to long-term duration electricity disruption events.

• The supply and delivery of fuel to the city’s water- and sewer pump stations and its water- and wastewater treatment works will have to be planned.

• Alternate energy and power generation at wastewater treatment and works can reduce, if not eliminate, the costs associated with standby power.

Water has been recognised as one of the critical elements for sustainable socio-economic development and set at the core of sustainable development (Saravanan et al., 2009). It is directed towards ensuring the improvement of health and living conditions, and, in turn, sustaining the use of natural resources, with the goal of providing a better life for all. Thus, regulating and sustaining this resource is of utmost importance. However, about 1.1 billion people lack access to safe drinking water worldwide (Harshfield et al., 2009), and as such depends on available freshwater resources for drinking and domestic purposes.

Unfortunately, the qualities of many of these freshwater resources are often compromised by industrial- and treated municipal wastewater effluents, thus subjecting such communities that directly rely on such freshwater resources including rivers, streams, wells, dams, pond water sources to the risk of contracting waterborne diseases such as cholera (District et al., 2014).

Waterborne pathogens and related diseases are a major public health concern worldwide, not only because of the morbidity and mortality they cause, but also the cost and effort required for their prevention and treatment. The presence of pathogens and other contaminants of human health concern in water is directly related to poor waste management, leading to water quality deterioration and pollution. The main pathways through which water of poor quality affects human health resulting in various waterborne disease is through drinking water and recreational activities. Exposure to contaminants through drinking water and recreational water activities can lead to adverse health effects, including gastrointestinal illness, reproductive problems, and neurological disorders. Strict measures exist both locally and internationally to ensure that water for public use meets a certain standard to ensure it is safe, clean and free from chemicals and organisms that cause disease.

Findings from several Water Research Commission (WRC) funded projects show increased levels of water pollution from contamination events, untreated sewage, anthropogenic sources, natural occurrences such as climate change and social drivers. Coupled with reported cases of water related disease outbreaks there is now a requirement of new thinking and working around how public health can best be protected from emerging and re-emerging water related illnesses. Key to this is the need for proper assessment of contaminants in water and regular water quality monitoring as measures for early warning and the prevention of waterborne outbreaks

Of encouragement is the development of monitoring and response guidelines which will prove critical in the overall agenda of adequately managing health-compromising outbreaks. The Water Research Commission Report: Report No 2432/1/18 is one of such reports.

Supporting sustainable development through research funding, knowledge creation and dissemination

A velocity of 1 meter per day or greater is a high rate of movement for groundwater, and groundwater velocities can be as low as 1 meter per year or 1 meter per decade. In contrast, velocities of streamflow generally are measured in meters per second. A velocity of 1 meter per second equals about 86 kilometres per day.

FAST-FACTS – Groundwater

1. Introduction and context The interactions between humans and the hydrological cycle and how this interaction has transformed the fresh water systems have been explored by Vorosmarty et al (2013) who identified five major human pressures on fresh water resources such as increasing water withdrawals, building of large dams, increasing pollution, expansion of invasives and declining streamflow which is projected to decline well into the future, as illustrated in Figure 1.

Figure 1: Five major interactions of humans with fresh water systems (source: Vorosmarty et al, 2013)

These interactions or human pressures on fresh water lead to alterations in the stocks and flows of water that change its availability in space and/or time. The key factors that affect water availability include climatic variability and change, population growth that reduces per capita water availability, contamination that reduces usable water supplies, physical overuse of a stock such as groundwater overdraft and technological factors (Vorosmarty et al, 2013). The impacts of these multiple driving alterations in water availability need to be continuously assessed (Montanari et al, 2013) through measurements of hydrological variables to continually assess the quantities and usability of water as a foundation for water security (Lawford et al, 2013). The adoption of the Sustainable Development Goals (SDGs) specifically SDG 6 has created an increased demand for extensive observations of good quality data and more dense monitoring networks especially in developing countries (Tauro et al, 2018). Despite being a developing country, South Africa has a

long history of hydrological monitoring which dates back to the late 19 th century and early 20th century. The aim of the hydrological monitoring is to measure precisely where and in what quantities water is stored, and how the water moves between those stores. It is from these observations that the spatial distribution of rainfall, runoff, soil moisture, evapotranspiration, etc are determined. The observation networks in South Africa also provided further evidence of a non- linear relationship between rainfall and runoff as illustrated in Figure 2 (Schulze, 2011). Schulze (2011) reasoned that the non-linearity of the runoff response to rainfall can be attributed to antecedent conditions in a catchment, with a larger proportion of rainfall being converted to runoff when a catchment is wetter or because the soil water content just prior to a rainfall event may have been high as a result of previous rainfall. With a mean annual precipitation (MAP) of approximately 500 mm, the translation of rainfall to runoff in South Africa is estimated to be approximately 10% (see Figure 2) which is low by any standards and hence the country has a natural, physical water scarcity issue.

Figure 2: The non-linear rainfall- runoff relationship for selected streamflow gauging points in the summer rainfall region of South Africa (after van Biljon, Cornelius and Moore, 1987 quoted in Schulze, 2011).

There are two primary sources of hydrological data that are required in the assessment, evaluation and management of water resources, and these include rainfall and streamflow data (Dent, 1994). The existing standard methods of rainfall and streamflow measurements consists mainly of rain gauges and weirs and flumes, respectively. However, the in situ observation networks for these fluxes tend to be limited due to a lack of technical and institutional capacity and a lack of investment in maintaining and sustaining these observation networks. This is especially true for developing countries ‘where not only data are scarce but where pressure on water resources is often already very high and increasing’ (Zogheib et al, 2018). Furthermore, technologies to measure these fluxes have evolved over the last few decades but the uptake for these technologies has been slow in developing countries.

Therefore, the objective of this paper is to highlight the challenges with the current hydrological monitoring network and to explore the potential use of innovative technologies to supplement the steadily declining in situ observations in South Africa.

2. Challenges with hydrological monitoring in South Africa The continuous assessment of water resources is essential for water resource management, and two of the key hydrological fluxes that must be measured for this purpose are rainfall and streamflow. Worldwide, there has been a decline in hydrological networks (Muller et al., 2015; Stewart et al., 2015). For example, Lorenz and Kunstmann (2012) observed that operational rain gauge networks throughout the world are decreasing, and that the extent of research rainfall gauge networks worldwide are limited (Sunilkumar et al., 2016). The declining observation networks is acute in developing countries, and Hughes (2008) attributes the many challenges in the collection and maintenance of rainfall and streamflow data to the socio-economic and political history of southern Africa where data collection was not regarded as a priority. However, adequate and operational hydrological networks are required to provide information that informs decisions in water resource management and to provide accurate and timely warning for droughts and floods (Sene and Farquharson, 1998). For example, a recent study by the WRC (Abiodun et al, 2018) which characterised drought trends in southern Africa from 1950 to the present showed that there has been an increase in the intensity, area coverage and frequency of droughts and that the projected all-dry drought patterns (dry conditions) would become more frequent while all-wet drought patterns (wet conditions) would become less frequent over the entire southern Africa as illustrated in Figure 3.

Climate change projections by Christensen et al. (2007) and confirmed by Engelbrecht et al. (2009) suggest that the mean annual rainfall will decrease and evapotranspiration will increase across much of subtropical southern Africa. This has huge implications for water resources and thus more detailed hydrological monitoring will be required to inform decision-making and informed responses to the reduction in water availability.

Figure 3: Drought patterns in southern Africa from 1950 to present (Abiodun et al, 2018).

Furthermore, the decline in observation networks has been accompanied by the decline in the quality of the data measured from the limited hydrological networks. The current challenges with rainfall and streamflow collection networks in South Africa are briefly highlighted below.

Rainfall is the key input parameter in hydrological modelling for water resources assessment and management. Rain gauge density and data length are two important considerations when analysing rainfall data for water resource management. Mishra (2013) found that the level of accuracy in rainfall measurement is highly dependent on the density of the rain gauge stations. Rainfall events vary spatially and temporally within a catchment and a dense rain gauge network may be able to better capture rainfall characteristics (Krajewski et al., 2003; St-Hilaire et al 2013). A denser rainfall network improves the simulated total streamflow (St‐Hilaire et al., 2003), improves areal estimates of rainfall and reduces underestimation of cumulative rainfall (Bárdossy and Das, 2008; St-Hilaire et al., 2003). Xu et al. (2013) demonstrate that a dense rain gauge network improves the

estimation of the Mean Annual Precipitation (MAP), and that runoff estimates are improved with rain gauges that are strategically located rather than rain gauge density (St-Hitlaire et al., 2003).

The responsibility for the collection of rainfall data resides primarily with the South African Weather Services (SAWS), though some rainfall data is also collected by the Agricultural Research Council (ARC) for agricultural applications and the Department of Water and Sanitation (DWS) collects limited rainfall data next to major dams for water balances. According to Pegram et al. (2016) the current rain gauge network in South Africa consists of approximately 1200 gauges compared to approximately 3800 rain gauges in the 1970s, and this rain gauge network is steadily declining every year. Pitman (2011) observed that the number of open rainfall stations that were useful for water resource assessments in 2004 is far below the number of rainfall stations in the 1920s as illustrated in Figure 3. This number of operational rainfall stations is steadily declining each year due to budget cuts and weakening technical and institutional capacity in the data collection agencies. The decline in observation networks is associated with periods of social and political upheaval according to Rodda et al. (2016).

Lately data collection agencies have resorted to imposing a fee to access the rainfall data with strict conditions on the sharing and distribution. By imposing fees and strict conditions on access and sharing of rainfall data the data collection agencies are crippling the efforts to prudently manage water resources in a country whose variable water resources are becoming scarcer due to population growth and increasing drought intensities and frequencies. However, there are earth observation (EO) technologies on rainfall estimation that the country could take advantage of to supplement the shrinking in situ rainfall observation networks. These technologies are discussed later in section 3.

Figure 4: Number of useful rainfall stations for water resource assessment (Pitman, 2011; WR2012)

The first long-term stage measurement in South Africa started in 1865 in the Port Elizabeth Town council (Wessels and Rooseboom, 2009). This was followed by daily stage measurements at the Vaal River in Riverton in 1885 and another gauging station was established in 1898 on the Breede River near Robertson (Wessels and Rooseboom, 2009). Therefore, South Africa has a long history

of streamflow measurements using conventional flow measurements methods such as weirs, flumes, etc. Figure 4 shows the growth and decline in streamflow measurements in South Africa from 1920 to 2010 (WR2012). The rapid growth in flow measurements started between the 1950s and peaked to approximately more than 1200 stations around the 1990s. However, there was a rapid decline in the number of operational gauges shortly after 1990 due to the closure of a number of stations that were found to be non-compliant with gauging standards (Wessels and Rooseboom, 2009). However, the steady decline in the number of open stations continued long after 1990 to reach approximately 450 stations that were regarded as useful for water resource assessments (Pitman, 2011). Although Wessels and Rooseboom (2009) attributed this decline in flow measurements to financial constraints, however, the dwindling technical and institutional capacity within the Department of Water and Sanitation (DWS) plays a major role in the country’s (in)ability to maintain and sustain the hydrometric networks.

Figure 5: The growth and decline of flow measurements since the 1920s (after WR2012). The y-axis is the number of flow measuring stations x10.

The Department of Water and Sanitation (DWS) has the primary responsibility for the monitoring of streamflow in South Africa (Pitman, 2011). The flow measurements in South African rivers are complex due to high variability in rainfall which leads to high variability in water discharges coupled with heavy sediment and debris loads (Wessels and Rooseboom, 2009). Therefore, the loads in flows have negative impacts on the quality and reliability of gauged streamflow data and this necessitates the calibration of the flow gauging stations at least twice a year. Furthermore, the quality of the flow data may be affected by the discontinuation of the flow gauging, stage damage, and the exceedance of a discharge table which results in the failure to record high flows (van Bladeren et al., 2007).

There are emerging innovative technologies for streamflow estimation that may be useful to supplement the declining flow measurement networks, and these will be discussed in the next section.

3. Opportunities for deploying innovative technologies for hydrological monitoring Over the last twenty years the accuracy and precision in the assessment of water resources in South Africa has become uncertain and less reliable due to the declining observation networks and the deteriorating data quality. Large parts of the country have become ‘ungauged’ and thus their water stores and flows cannot be assessed with certainty. The high cost of traditional hydrological monitoring is always cited as the main reason that hamstrings the sustenance and expansion of in situ or ground-based observation networks. However, the development of remote sensing technologies such as satellite imagery and smart sensors provide opportunities to generate substantially more data at less cost, and at high spatial and temporal resolutions. These remote sensing technologies are increasingly cheaper and efficient (i.e. doing more for less) in that frequent site visits are not necessary. However, it should be emphasised that the remotely sensed technologies have been developed and deployed as a supplementary source of data collection; they still need dense gauge networks for ground referencing and calibration (Pegram et al., 2016).

The section below provides a brief overview of the existing remote sensing infrastructure that can aid the country in monitoring its water stores and flows.

3.1 Remote sensing technology for rainfall 3.1.1 Radar network Weather radars provide quantitative estimates of rainfall/precipitation with high spatial and temporal resolution. They are deployed largely to observe extreme weather phenomena. With more than half of the country being semi-arid with a mean annual precipitation (MAP) of less than 500 mm rainfall, South Africa tends to receive large-scale flood events which are often triggered by prolonged periods of drought. A large fraction of this rainfall results from convective storms which lead to the formation of rain fields with high variability in space and time (Terblanche et al., 2001). The rain fields are not well captured by standard rain gauge networks and therefore the deployment of radar network was intended to address this problem. Terblanche et al, (2001) investigated the potential use of radar in hydrological application in South Africa, and their promising findings led to the development of a Radar Data Acquisition System which was not fully utilised due to limited resources. Developed countries such as the UK, USA and other European countries have successfully integrated weather radar data with in situ rain gauges for hydrological applications such as drought and flood warning and water resource management systems.

The erstwhile Department of Water and Environmental Affairs invested approximately R240 million in a new, state-of-the-art national weather radar network (Figure 6) which includes nine (9) single-polarised S-band radars, one (1) dual-polarised S-band radar, two (2) mobile X-band research radars and five (5) C-band radars. South Africa should utilise this national radar network to vigorously pursue the integration of the rain gauge networks and weather radar data for hydrological applications.

There is a wealth of local knowledge and radar data-rain gauge data integration systems that have been developed through WRC-funded research over the last twenty years (Mittermaier and Terblanche, 2000; Pegram and Clothier, 2001; Terblanche, Pegram and Mittermaier, 2001; Clothier and Pegram, 2002; Pegram and Sinclair, 2002; Kroese, 2004; Kroese et al., 2006; Sinclair and Pegram, 2004 and 2009; Wesson and Pegram, 2006; Vischel et al., 2008, etc) but these systems remain to be integrated operationally in the national monitoring infrastructure.

It should be noted that raw radar data alone has many errors especially when estimating floods, and therefore it must be calibrated and combined with in situ rain gauge data (Sun et al., 2000). Furthermore, the maximum range of radars is approximately 300 km and thus

they have limited coverage, as shown in Figure 6. To address the errors, Bárdossy and Pegram (2017) developed a methodology to combine daily precipitation observations and radar measurements to estimate sub-daily extremes at point locations.

Latterly, a WRC-funded project (Burger, et al, 2019) pointed out that only 54.3% of the radar data collected over the last 12 months is available but most of it is unusable as most of the radars are not calibrated. The calibration of the radar is hamstrung by the lack of technical capacity and resources within South African Weather Services (SAWS) which struggles to keep the radars operational. This issue needs to be resolved if the country is to benefit from its multimillion rand investment in national radar network.

Figure 6: Current weather radar network in South Africa (Burger, et al 2019)

3.1.2 Rainfall from satellites Rainfall is the main driver of the water/hydrological cycle and it is variable in space and time. Therefore, an accurate record of its coverage is necessary to improve weather and climate forecasting and predictions. With the decline of ground-based point measurements such as rain gauge networks, rainfall can be estimated remotely, either from ground-based weather radars (as described in Section 3.1.1) or from satellites. There is a number of weather satellites orbiting the space from which rainfall can be estimated, and these include, among others, MeteoSat, Tropical Rainfall Measuring Mission (TRMM) which was decommissioned in 2015, the Global Precipitation Measurement (GPM) which builds on TRMM successes, etc. The GPM was deployed by NASA to provide full global coverage of precipitation every 2–3 hours to assist researchers in improving the forecasting of extreme events, studying global climate, and adding to current capabilities for using such satellite data to benefit society. Globally, satellites provide three quarters of the data used in numerical weather prediction models, and in France satellites provide 93% of data used in numerical weather forecasting models (OECD, 2014). In countries with sparse rain gauge networks, rainfall may be estimated using satellites. Several studies have also used satellite-derived rainfall to estimate streamflow. Grimes and Diop (2003) investigated the feasibility of using satellite-derived daily rainfall as input to a rainfall-runoff model for a

river flow forecasting in a poorly gauged catchment in West Africa. The study proved that satellite-derived rainfall estimates gave more accurate river flow forecasts than when using rain gauge data alone. Another study conducted in South Africa by Sawunyama and Hughes (2008) confirmed the potential of using satellite-derived rainfall to extend rainfall data for water resource modelling. Botai et al (2018) investigated the spatial-temporal variability and trends of precipitation concentration across South Africa using the Tropical Rainfall Measuring Mission (TRMM) satellite precipitation data sets spanning 1998-2015; while Bárdossy and Pegram (2017) developed a methodology to combine daily precipitation observations and radar measurements to estimate sub-daily extremes at point locations.

Tauro et al (2018) declare that all possible rainfall data sources such as rain gauges, radar data, satellite-derived data, etc need to be consolidated to provide better rainfall estimation. This assertion is pertinent to South Africa where in situ rain gauge network has been steadily declining for three decades. The processed and raw weather satellite data is freely accessible from NOAA, and the South African National Space Agency (SANSA) which “…was created to promote the use of space and strengthen cooperation in space-related activities while fostering research in space science, advancing scientific engineering through developing human capital, and supporting industrial development in space technologies” (SANSA website) and the South African Weather Services (SAWS) have the infrastructure to access and process raw weather data, and disseminate it to the nation.

3.2 Soil moisture from satellites Water stored in the 5 cm to 17 cm of the topsoil represents a key variable in the climate and hydrology systems as it modulates the exchange of moisture and energy between the land surface and the atmosphere (McColl, et al., 2017). Therefore, the knowledge of this subsurface water component (soil water content) is essential for water balance studies, irrigation water use efficiency, floods and droughts applications. However, it is difficult to quantify the behaviour and dynamics of soil moisture due to sparse and uneven observations (McColl, et al., 2017). Soil moisture is estimated using soil moisture probes, time-domain reflectometry (TDR), gravimetric methods, etc but the measurements from these methods have proved laborious with sparse observation networks. Over the past decade satellite remote sensing of soil moisture has significantly advanced to the extent that there are two dedicated missions in space (Tauro et al, 2018) and these missions include Soil Moisture Ocean Salinity (SMOS) and Soil Moisture Active and Passive (SMAP) which was launched by NASA in 2015. SMAP was specifically designed to provide globally comprehensive and frequent measurements of the moisture in the topsoil, and the observations are collected globally every two to three days. After almost two years of data collection, the efficacy of SMAP was evaluated by McColl et al (2017) and found to provide unprecedented levels of detailed information on the amount of water stored in the topsoil layer.

In South Africa, two different approaches (i.e. hydrological modelling and remote sensing) of soil moisture estimation have been used. For example, a series of WRC-funded projects (K5/1683 and K5/2024) produced a national soil moisture modelling framework running at 3-hour time-steps. The approach was automated to model soil moisture state in detail over Southern Africa using the PyTOPKAPI hydrological model forced by rainfall and evapotranspiration estimates. This led to the development of an operational soil moisture from satellite system (temporarily hosted by ARC) in which the soil water content is estimated every three (3) hours, and this work was extended to the SADC Region through the HYLARSMET project (K5/2324). Furthermore, the hydrological modelling approach and the remote sensing method were compared and found to have a good correspondence.

In conclusion, an operational national scale soil moisture modelling in which the modelling of national soil moisture status at 3 hour intervals is already set-up. Although updated monthly, it is capable of near-real-time operation.

Another relatively new ground-based technique for soil moisture estimation is the Cosmic Ray Probe (CRP) which provides area-averaged soil moisture estimates over hundreds of metres. The measurement depth ranges between 12–72 cm and is dependent on the soil moisture status. The Cosmic Ray Probes have been installed in parts of KwaZulu-Natal, Gauteng and Limpopo Provinces but the network is sparse.

3.3 Surface water observations This section is liberally using the text by: • Tauro, F. et al (2018). Measurements and observations in the XXI century (MOXXI): innovation and multi-disciplinarity to sense the hydrological cycle. Hydrological Sciences Journal, 63(2): 169-196 • Tauro, F., Petroselli, A. and Grimaldi, S. (2018). Optical sensing for stream flow observations: a review. Journal of Agricultural Engineering, Vol. XLIX: 836 Tauro et al (2018) declare that the scarcity of streamflow observations is a major source of uncertainty in hydrology and water resource management. Streamflow cannot be directly measured either with ground-based instruments or with satellite remote sensors; it is estimated from water level or velocity measurements of surface. The decline in ground-based streamflow monitoring networks due to budget cut-backs is a major impediment in frequent monitoring campaigns or the implementation of dense networks of measurement stations. For that reason the hydrology research community has adopted image-based techniques such as satellite imagery, laser altimetry, radar altimetry, unmanned aerial vehicles (UAV) or drones, etc to measure water levels. Furthermore, remarkable effort has been devoted to the development of non-contact or non-intrusive flow sensing observations such as the large-scale particle image velocimetry (LSPIV). LSPIV entails the imaging of the field of view and image ortho-rectification through transformation scheme, and image processing by high-speed cross-correlation.

In the developed countries such as the US, UK, etc these alternative flow sensing technologies are implemented and integrated in the standard ground-based observations, and the results are encouraging. South Africa should glean experience from the implementation of these technologies from elsewhere in the world and to investigate their potential deployment and implementation in this country.

3.4 Citizen monitoring There exist many opportunities for the implementation of citizen monitoring e.g. for rainfall/climate, stream flow measurement, etc. Frameworks to integrate citizen data with the mainstream national datasets have been developed here in South Africa and elsewhere in the world. These frameworks can be implemented seamlessly if the proper coordination mechanisms are established.

4. Other interventions 4.1 Collation and coordination of water-relevant data (central repository or hydrology data centre) The analysis above has demonstrated that alternative technologies for water stores and flows exist and have been tested elsewhere in the world and even here in South Africa. The country has some infrastructure and the systems to implement these technologies but there is a lack of coordination at a strategic level to pool the resources. Therefore, it is proposed to establish a national central repository to coordinate all water-relevant data in which the new technologies could be tested and disseminated.

• Abiodun, B. et al (2018). Regionally extensive droughts and climate change in southern Africa: mechanisms, model reliability and projections. WRC Report No. 2317/1/17, Water Research Commission, RSA. • Bárdossy, A. and Das, T. (2008). Influence of rainfall observation network on model calibration and application. Hydrology and Earth System Sciences Discussions, 12(1): 77-89. • Bárdossy, A. and Pegram, G. (2017). Combination of radar and daily precipitation data to estimate meaningful sub-daily point precipitation extremes. Journal of Hydrology, 544: 397- 406.

• Botai, C.M., Botai, J.O. and Adeola, A.M., 2018. Spatial distribution of temporal precipitation contrasts in South Africa. South African Journal of Science, 114 (7-8), 70-78. • Boughton, W. (2007). Effect of data length on rainfall–runoff modelling. Environmental Modelling & Software 22 (3): 406-413. • Burger R., Havenga, H., Hiscutt, F., Belelie, M., Ayob, N. and Kucera, P. (2019). Quantifying rainfall using rain gauges, radar and satellite – realtime technologies to facilitate capacity building. WRC Project No. K5/2062 (report in press), Water Research Commission, RSA.

• Christensen, J.H., et al. (2007). Regional climate projections. Climate Change, 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, University Press, Cambridge, Chapter 11: 847–940. • Clothier, A.N. and Pegram, G.G.S. (2002). Space-Time Modelling of Rainfall using String-of- Beads Model: Integration of Radar and Rain-gauge Data. WRC Report No. 1010/1/01, Water Research Commission, RSA.

• Dent, J. (1994). The parlous state of hydrometry overseas. Circulation 44 14-15. • Engelbrecht, F.A., McGregor, J.L. and Engelbrecht, C.J. (2009). Dynamics of the conformal- cubic atmospheric model projected climate-change signal over southern Africa. International Journal of Climatology, 29: 1013–1033. • England Jr, JF, Cohn, TA, Faber, BA, Stedinger, J.R., Thomas Jr, W.O., Veilleux, A.G., Kiang, J.E. and Mason Jr, R.R. (2018). Guidelines for determining flood flow frequency—Bulletin 17C. In: Hydrologic Analysis and Interpretation. US Geological Survey, Reston, Virginia.

• Grimes, D.I.F and Diop, M. (2003). Satellite-based rainfall estimation for river flow forecasting in Africa. I: Rainfall estimates and hydrological forecasts. Hydrological Sciences Journal, 48(4): 567-585 • Krajewski, W.F., Ciach, G.J. and Habib, E. (2003). An analysis of small-scale rainfall variability in different climatic regimes. Hydrological Sciences Journal, 48(2): 151-162. • Kroese, N. (2004). Spatial interpolation and mapping of rainfall (Simar): Vol 1.

Maintenance and upgrading of radar and rain-gauge infrastructure. WRC Report No. 1151/1/03, Water Research Commission, RSA. • Kroese, N., Visser, P. J. M., Nhlapo, A., Mngadi, P., Terblanche, D. E. and Banitz, L. (2006). Daily Rainfall Mapping over South Africa (DARAM): Infrastructure and Capacity Building. WRC Report No. 1426/1/05, Water Research Commission, RSA. • Lawford, R., Strauch, A., Toll, D., Fekete, B. and Cripe, D. (2013). Earth observation for global water security. Current Opinion in Environmental Sustainability, 5: 633-643.

• Lorenz, C. and Kunstmann, H. (2012). The hydrological cycle in three state-of-the-art reanalyses: Intercomparison and performance analysis. Journal of Hydrometeorology, 13 (5): 1397-1420. • Mittermaier, M. P. and Terblanche, D. E. (2000). The integration of daily rain gauge and radar rainfall estimates for the Liebenbergsvlei catchment, north-eastern Free State. South African Journal of Science, 96(11/12), 589-593.

• Mishra, A.K. (2013). Effect of rain gauge density over the accuracy of rainfall: a case study over Bangalore, India. SpringerPlus, 2: 311.

• Montanari, A. et al (2013). Panta Rhei – everything flows: change in hydrology and society – the IAHS Scientific Decade 2013-2022. Hydrological Sciences Journal, 58 (6): 1256-1275. • Muller, C., Chapman, L., Johnston, S., Kidd, C., Illingworth, S., Foody, G., Overeem, A. and Leigh, R. (2015). Crowdsourcing for climate and atmospheric sciences: current status and future potential. International Journal of Climatology, 35 (11): 3185-3203.

• OECD (2014). “Satellite weather and climate monitoring”, in The Space Economy at a Glance 2014, OECD Publishing, Paris. • Pegram, G. G. S. and Clothier, A. N. (2001). High resolution space-time modelling of rainfall: The “String of Beads” model. Journal of Hydrology, 241:26-41. • Pegram G., Sinclair, S., and Bárdossy, A. (2016) New methods of infilling southern African raingauge records enhanced by annual, monthly and daily precipitation estimates tagged with uncertainty. WRC Report No. 2241/1/15, Water Research Commission, RSA.

• Pitman, W. (2011). Overview of water resource assessment in South Africa: current state and future challenges. Water SA, 37 (5): 659-664. • Sawunyama, T. and Hughes, D.A. (2008). Application of satellite-derived rainfall estimates to extend water resource simulation modelling in South Africa. Water SA, 34 (1), 1-10. • Sinclair, S. and Pegram, G. G. S. (2004). A flood nowcasting system for the eThekwini metro. Volume 1: Umgeni Nowcasting Using Radar – An Intergrated Pilot Study, WRC Report No. 1217/1/03, Water Research Commission, RSA.

• Sinclair, S. and Pegram, G. G. S. (2009). A comparison of ASCAT and modeled soil moisture over South Africa, using TOPKAPI in land surface mode. Hydrology and Earth System Sciences, 6: 7439–7482. • Rodda, J.C., Pieyns, S.A., Sehmi, N.S. and Matthews, G. (1993). Towards a world hydrological cycle observing system. Hydrological Sciences Journal, 38 (5): 373-378. • Schulze, R.E. (2011). Rainfall: Background. In: Schulze, R.E. (2011). A 2011 Perspective on Climate Change and the South African Water Sector. Water Research Commission, Pretoria, RSA, WRC Report No. TT 518/12, Chapter 3.3: 85-89.

• Sene, K. and Farquharson, F. (1998). Sampling errors for water resources design: the need for improved hydrometry in developing countries. Water Resources Management, 12 (2): 121-138. • Smith, D. (1994). Flood damage estimation-A review of urban stage-damage curves and loss functions. Water SA, 20 (3): 231-238. • Smith, D., Viljoen, M. and Spies, P. (1981). Guidelines for Assessing Flood Damage in South Africa. Water Research Commission, Pretoria, South Africa • Smithers, J.C. and Schulze, R.E. (2001). A methodology for the estimation of short duration design storms in South Africa using a regional approach based on L-moments. Journal of Hydrology, 241 (1-2): 42-52. 51 • St-Hilaire, A., Ouarda, T.B., Lachance, M., Bobée, B., Gaudet, J. and Gignac, C. (2003).

Assessment of the impact of meteorological network density on the estimation of basin precipitation and runoff: a case study. Hydrological Processes, 17 (18): 3561-3580. • Stewart, B. (2015). Measuring what we manage-the importance of hydrological data to water resources management. Proceedings of the International Association of Hydrological Sciences, 80. IAHS Press, Paris, France. • Sun, X., Mein, R., Keenan, T. and Elliott, J. (2000). Flood estimation using radar and rain gauge data. Journal of Hydrology, 239 (1-4): 4-18.

• Sunilkumar, K., Rao, T.N. and Satheeshkumar, S. (2016). Assessment of small-scale variability of rainfall and multi-satellite precipitation estimates using measurements from a dense rain gauge network in Southeast India. Hydrology and Earth System Sciences, 20 (5): 1719. • Tauro, F., et al (2018). Measurements and observations in the XXI century (MOXXI): innovation and multi-disciplinarity to sense the hydrological cycle. Hydrological Sciences Journal, 63 (2): 169-198.

• Terblanche, D.E., Pegram, G.G.S. and Mittermaier, M.P. (2001). The development of weather radar as a research and operational tool for hydrology in South Africa. Journal of Hydrology, 241 (1-2): 3-25 • van Bladeren, D., Zawada, P. and Mahlangu, D. (2007). Statistical Based Regional Flood Frequency Estimation Study for South Africa Using Systematic, Historical and Palaeoflood Data: Pilot Study, Catchment Management Area 15. WRC Report No. 1770/1/06, Water Research Commission, RSA.

• Vischel, T., Pegram, G. G. S., Sinclair, S. and Parak, M. (2008). Implementation of the TOPKAPI model in South Africa: Initial results from the Liebenbergsvlei catchment, Water SA 34(3): 331–342 • Wessels, P. and Rooseboom, A. (2009). Flow-gauging structures in South African rivers Part 1: An overview. Water SA, 35 (1): 1-9. • Wesson, S. M. and Pegram, G. G. S. (2006). Improved radar rainfall estimation at ground level, Natural Hazards and Earth System Science, 6(3): 323–342.

• WR2012 (Water Resources of South Africa 2012). Available from: http://waterresourceswr2012.co.za. • Xu, H., Xu, C-Y., Chen, H., Zhang, Z. and Li, L. (2013). Assessing the influence of rain gauge density and distribution on hydrological model performance in a humid region of China. Journal of Hydrology, 505: 1-12. • Zogheib, C., Ochoa-Tocachi, B.F., Paul, J.D., Hannah, D.M., Clark, J. and Buytaert, W. (2018).

Exploring a water data, evidence, and governance theory. Water Security, 4-5: 19-25.

In one of the first studies of its kind in South Africa, the Water Research Commission (WRC) undertook research to investigated the presence of microplastics in South African freshwater, the areas of focus included rivers of the North West, Gauteng and Free State, as well drinking and groundwater sources. The additional benefit of this study is that it enables a baseline to be set for South Africa for the first time as well as developed and tested laboratory methods for detention and quantification of microplastics in freshwater sources. This study further emphasizes the need for a more coordinated approach for addressing plastic pollution from source to sea.

While plastic pollution in the marine environment is well documented, there are few studies on the extent of pollution in freshwater and treated water sources. The scoping study attempted to characterise the presence, levels and potential implications of microplastics in freshwaters as well as provide recommendations on areas of concern, as well as research gaps and future priorities for South Africa.

Environmental pollution is occurring on a vast and unprecedented scale around the globe. This is largely due to the increasing manufacture, use and release of toxic substances to the environment, significantly altering the natural systems on a global scale. This surge in the use of plastic has led to their massive release into the environment resulting in one of the biggest global environmental concerns.

To address some of these serious legacy pollution challenges, countries have ratified a number of global conventions and agreements, such as the Stockholm Convention which deals with persistent organic pollutants (POPs), the Minamata Convention dealing with mercury, and so forth. However, there are emerging and new pollutant issues, which are currently not covered where there is a clear concern. Plastic and microplastic pollution, along with related nanoparticles, is one such ‘emerging’ concern and as evidenced in the study, low to medium amounts of plastic particles in surface, tap, and groundwater sources in South Africa were demonstrated in some of the areas of focus. However, and in turn higher microplastic levels have been reported in developed countries, such as China, US and in some European states.

Microplastics (particles less than 5 mm in size) have two main sources: primary sources which are the manufactured microplastics (such as microbeads found in beauty products) and secondary microplastics, which are the fragments that result from the degradation of larger plastic pieces. The major groups of microplastics based on origin and shape are primary particles, secondary fragments and fibres.

Supporting sustainable development through research funding, knowledge creation and dissemination

Findings from this study have provided insights on some of the hot spot areas and potential threats of plastics to environmental health. In addition, the scoping study has highlighted gaps where action is required.

As follow-up actions, the following is recommended;

• Review and tighten South Africa’s response to plastic pollution. Implementation of the waste research development and innovation roadmap needs to be strengthened in order to provide much needed guidance on plastic waste management in the South African environment. • Efforts for addressing plastic pollution using the source-to-sea concept should be stepped up to fill the knowledge gaps of the various risks associated with environmental exposure to plastics, and better manage the flow of plastic material from various sources.

• There is a need to increase awareness on plastic pollution. The Consumer Protection Act and other related legislation, such as The Foodstuffs Cosmetics and Disinfectants Act and its Regulations, the Food Labelling Regulations (R146), Agricultural Products and Standards Act and its regulations, and the various South African Bureau of Standards (SABS) product packaging and labelling standards, should be strengthened in order to enforce declaration of the presence of plastic ingredients, and also inform the consumer on the recyclability and re-usability of the product.

• Plastic packaging seems to be the most obvious and visible component of inland plastics pollution. Given market forces and few regulations, meaningful voluntary reduction of the plastic components of packaging, or promoting the use of recyclable or reusable plastics (which are more expensive), seems remote. However, even ‘remote’ opportunities can be advanced, and these opportunities should be investigated.

The issue of microplastics and their impact on the environment is an emergent one that requires more research. The WRC and its partners have committed to a follow-up study to the scoping study on microplastics in freshwater and in partnership with the Department of Environmental Affairs and the Department of Water and Sanitation will be focus on a body

For further information on this report, please contact the WRC or visit the WRC website.

Microplastics in freshwater environments – A scoping study (Project no. K5/2610). For content- related queries please go to; www.wrc.org or contact Research Manager, Dr Nonhlanhla Kalebaila | nonhlanhlak@wrc.org.za | Tel: (012) 761-9300 ; Ms Khosi Jonas | khosij@wrc.org

Our current global resource model is linear in nature; it involves take-use-dispose. This model can lead to wastage and has little emphasis on resource optimisation. With consumption of global resources expected to rise due to increasing population size, new ways of resource optimisation are required to ensure we do not consume beyond what we have. One of the new economic models that has been gaining traction is based on circular economy principles. In this approach, the continual and/or efficient use of resources through reduction, reuse and recycling is promoted. Circular economy models attempt to create a closed-loop system, minimising the use of resources and the creation of wastes.

In sanitation, the current take-use-dispose models are wasteful. We routinely used two modes of sanitation. In urban centres, flush toilets are used. This technology uses 6 to 9 litres of drinkable water – of which there is a limited supply – to move our pee and poo in sewers until it reaches a wastewater facility. Once at a treatment facility, selected constituents in the wastewater are consumed by microorganisms. Eventually, these microorganisms grow to a point where the tanks that hold them need to be emptied. In South Africa, the majority of this “waste” ends up at land disposal sites.

Outside sewered areas, dry sanitation technologies are used. While saving on water, the technologies fill up with human waste becoming a thick sticky paste called faecal sludge. This faecal sludge needs to be emptied and is then transported to a centralised location for disposal, usually a land disposal site. Land disposal sites that can only handle a certain amount of sludge disposal and many can fill quickly if the balance is skewed more towards disposal than degradation. Growing population sizes mean ever-growing sanitation waste volumes to be treated.

With the number of land disposal routes expected to become limited, circular economy principles are being considered as a sustainable option to manage human faecal waste. At the Water Research Commission (WRC), South Africa’s premier water knowledge hub based in Pretoria, research is being undertaken to examine if the resources contained in human faecal waste can be repurposed into products of economic value thereby introducing circular economy principles into the management of human faecal wastes.

To understand what products of economic value can be extracted from human faecal waste, one needs to understand what is contained in our pee and poop. Water makes up the largest fraction of both our pee and poop. Pee or urine contains around 90% water Pee also contains essential plant macronutrients (Nitrogen, Phosphorus, and Potassium) that are routinely used in fertilisers. If pee can be separated from poo, there exist an opportunity to harvested and recycled these nutrients. In comparison, around two-thirds of poop is water. The remainder consisting of solid material with organic material represents the highest fraction followed by bacterial biomass, protein or nitrogenous matter, carbohydrate or any other non-nitrogenous undigested plant matter, and undigested lipids. These constituents can be extracted and properties changed through innovative engineering processes to manufacture products of economic value. Below are of some of the innovations tested that have been down to have this capability.

Large volumes of urine can cause eutrophication of water bodies that leads to oxygen depletion and subsequent adverse aquatic life effects. Several pee innovations have been demonstrated in South Africa that seek to repurpose urine. If urine can be separated from human waste streams, there exist an opportunity to repurpose it and prevent downstream

pollution challenges. At the University of KwaZulu-Natal, Professor Ademola Olaniran has shown that it is possible to convert urine through innovative engineering processes into struvite, a phosphate mineral that can used as a fertiliser. Professor Olaniran’s research also looked at health and safety implications for reusing urine-derived struvite for horticultural purposes. At the University of Cape Town (UCT), Dr Dyllon Randall has been exploring the production bio-bricks from urine. Dr Randall’s research collected urine from men’s urinals and feeding this to selected bacteria, a gelling-like substance was produced which binds masonry sand together to form a bio-brick. The research first aimed at illustrating the possibility; new research is aimed at optimising processing of products and developing the business models to scale up the innovations.

Bio-brick formation from urine undergoing stress testing

The capabilities for repurposing poop have also been demonstrated. By turning poop into products of economic value, there is opportunity to generate additional revenue streams from products that would otherwise be disposed of. Worldwide, many wastewater works are converting their plants into resource recovery facilities. The process used involves anaerobic digestion which coverts the fermenting waste into biogas. This biogas can be scrubbed and cleaned as reused for heating or generating electricity. More recent advancements involve producing renewable fuel options for motorised vehicles which can cut diesel usage and

reliance and greenhouse gas emissions. Several car manufacturers have noted the possibility; Toyota has developed a concept car that runs of fuel derived from poop waste. The concept car has hydrogen fuel cells which is fed with fuel derived from poop waste. In South Africa, BMW have been using a similar process at its facility in Bronkhorstspruit to supplement its electricity demand using cow poop and other organic wastes. This indicates that South Africa has capability to undertake such engineering projects and there exists potential to convert our wastewater treatment works into fuel generation centres.

Where there is potential for revenue, businesses will follow. In sub-Saharan Africa, large populations have no access to toilets. New social-driven business models have been sprouted in Kenya and Uganda to provide toilets and collect the human faecal wastes and convert into economic products. In Kenya, a social enterprise called Sanivation provides mobile toilets at households and the waste collected twice a week. This waste is then taken to resource recovery facility where the high temperatures in solar concentrators sterilise the waste which is then processed further turned into charcoal briquettes that are used as fuel for burning. In Uganda, Water for People have been using a similar approach to convert human sanitation waste into charcoal briquettes. As part of the business model, Water for People investigated the quality and market potential of the briquettes produced was compared to market-based fuel product, charcoal, that is used for household heating purposes. The investigations revealed that sanitation-derived briquettes can deliver the same fuel value as charcoal.

Other processes being demonstrated involve conversion of human faecal waste into protein feeds or commercial oils. While several of these concepts have demonstrated in South Africa through WRC research, it has yet to sprout resource recovery business models linked service delivery as happened in Kenya and Uganda. With many of these concepts having shown to be successfully demonstrated, the next stage is how we translate research into practice and develop the appropriate business tools for municipalities to utilise as part of their operations, including conducting user acceptance of alternate fuels, price-competitiveness among market- related products together and reliability of product quantity and quality.

Faecal waste re-purposed into briquettes. Image: Water for People Uganda

Please click here to download

Purpose:

• Facilitate direct engagement between media representatives and key stakeholders of the 14th IWA International Conference on Water Reclamation and Reuse.

Please click here to download