INFLUENCE OF CLIMATE CHANGE ON SURFACE WATER A STUDY FOR SOUTH AFRICA

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1 INFLUENCE OF CLIMATE CHANGE ON SURFACE WATER A STUDY FOR SOUTH AFRICA ADESOJI TUNBOSUN JAIYEOLA Department of Civil Engineering and Surveying Mangosuthu University of Technology Durban SOUTH AFRICA Corresponding author: jaiyeola@mut.ac.za, soj707@yahoo.com ABSTRACT Water is an essential resource for sustenance of life and for the region of South Africa. It is more important than any other natural resources. The vulnerability that water faces today and the possibility of an exacerbated future were introduced by multiple climatic changes hence exclusive attention is given to all the factors that influence water resources, particularly to surface water resources. For South Africa, water resources underpin the social, economic harmony of more than 12 million people so the various external forces driven by climatic changes that influence the availability and sustenance of surface water resources in South Africa was discussed in this study. This was achieved by reviewing temperature and precipitation change which contribute greatly to historic climatic changes. The result indicates a significant relationship between the current surface water condition in South Africa and historic trends in climatic changes. However, given that South Africa historic climatic data is not strongly maintained the study in this direction would require further understanding to create any statistic driven understanding. Key-Words: - Surface water; climate change; temperature; precipitation; South Africa; hydrological cycle; greenhouse gases. 1 Introduction Water is essential for life, however its availability and sustainable is subject to many factors that threatened its quality and quantity among this is climate change. According to [1], climate can be defines as the average weather in respects to means and variability considered over a specific time-span or certain region. In the same context climate change is a statistically significant variation of the mean state of the climate or of its variability lasting for decades or longer. Historic data is mounting and directing towards the understanding that we are at a stage of climate change brought upon by enhanced concentration of greenhouse gases and other pollutants. Among these there are gases like carbon dioxide whose level has been increasing since inception of industrial revolution. These and other associated factors may lead to significant level of climate change that will have local and global impact. Concerning its impact on surface water availability, climate change can have serious impact on hydrological cycle through precipitation, ISBN:

2 evaporation, transpiration and soil moisture erosion which happens due to increase in temperature. Furthermore, the hydrological cycle is expected to be intensified with more evaporation and precipitation. Specifically, for the case of hydrology and global water resources the understanding of climate change requires global level and multidisciplinary research that can help create holistic and sustainable solutions. According to studies conducted by IPCC (Intergovernmental panel for climate change) there has been significant change in the global surface temperature. It states that global surface temperature (mean) has gone up by 0.6 ± 0.2 degree Celsius since 1861, and had predicted a further increase in the range of 2 to 4 degree Celsius in coming century. Similarly, the impact is clearly visible on various water resources and as for sea the level has gone up by 10 to 25 cm since late 19 th century. The study indicates that as a direct impact of warmer temperature, the hydrological cycle is expected to undergo significant impact with changes accompanying in the form of rate of precipitation and evaporation. The study indicates that the impact would be significantly strong in the tropical region which is primarily part of developing countries. Such changes in regional temperature and precipitation level have significant importance as these have direct impact on the hydrological cycle. Variations in the parameters impacting these factors and hence amount of water that reaches the surface, evaporates or transpires need to be investigated and understood effectively. In this direction the assessment of hydrological impact of aquifers need information for changes in evapotranspiration as it is a key component of water balance. However, it is to be noted that climate-change situation tend to be expressed in terms of changes in temperature and precipitation. Therefore, the impacts of global warming on assumed evaporation (evapotranspiration) are not simple. The expected effect of climate change on surface water or evaporation (a sub format) depends on various characteristics of the site or location, like rivers and stream or other open sources as ponds and water reservoir. As the temperature increase the glaciers are retreating and increased summer runoff has become more prominent and the situation is bound to be more serious for coming decade. Similarly, various studies have documented the negative impact of climate change on streamflow and other watersheds across the globe. The impact of climate change and the relationship with surface water can be studies only through historical data study and building empirical models predicting the link between climate and regional hydrological regimes. In recent years, many researchers have used various empirical rainfall runoff models studying the impact of climatic change on hydrology. However, the application of such empirical relations with climate or geographical conditions is different due to region and associated factors. In this study the various external forces driven by climatic changes that influence the availability and sustenance of surface water resources in South Africa will be discussed. Also the effect of temperature and precipitation change which contribute greatly to historic climatic changes will also be analysed. 2 Overview of Water Condition in South Africa Water is life A popular proverb for a region like Africa, highlights the acute level of importance the continent places on water resource. Water is an essential and central resource in all its forms that may range from rainwater, aquifers, streams, ponds, springs, lakes, rivers, ocean water, snowpack ice to water vapours. The African continent with an area of approximately 30 million square kilometres has a comparatively higher level of natural resources as compared to any other region on the globe. According to [2] the natural resources for the region are not reflected in measures of the welfare of the region s inhabitants. In terms of geographical aspects the continent has some of the driest deserts, largest tropical rain forest and highest equatorial rain forest in the world. For the water resources the major share of continent s water resources are in a few countable regions of Congo, Niger, Nile, Zambezi and Lake Victoria. From these, the Congo watershed contains 10% of Africa s population but accounts for about 30% of the continent s annual run-off [3]. By the standards of WBGU [7] many of the African countries are under water stress and are using more than 20% of their renewable water resources. The historic data for the region of Nigeria shows the annual water withdrawal rate was at 28 cubic meters per person [4]. Similarly, the International dialogue on water and Climate change (2004) for the region of sub-sahara Africa noted that the water stress in this region will increase as the region is already relatively dry. The WBGU ISBN:

3 further highlights that a region is in a state of high water-related criticality i.e. susceptibility crises, if the water scarcity is combined with a poor problemsolving capacity of the population [6]. This is further accompanied by findings that 25 % of the contemporary African population has water stress, compared to 69% who live under relative water abundance [5]. However this abundance may not necessarily mean availability. According to historic reports by [8], an estimated 1,100 million people in the region of sub-sahara Africa do not have access to clean consumable water and the contaminated water is a leading cause of an approximate of 5 million deaths per year. Over a period of time, human activities and global climate change have collectively influenced the availability of water for consumption purpose. Human activities like forest clearing, afforestation, agriculture, etc, have adverse impact on the water cycle including evapo - transpiration, flow regimes, groundwater table and sea level. There are multiple threats to water availability for human consumption and the challenge ranges from water pollution (contamination of surface or ground water), water scarcity due to run-off condition or lowering of ground level of water and most importantly, global climate change that has led to consequences such as redistribution of precipitation, rising sea levels, change in the CO 2 absorption of the oceans and an increase of extreme precipitation events [7]. African countries are particularly prone to climatic changes due to desertification process, declining run-off from water catchments, decreased soil fertility, dependence on subsistence agriculture and inadequate government mechanisms along with increased population growth [9]. There are strong records and projections providing abundant evidences that water resources have the possibility of being strongly impacted due to climate change [10]. According to [11], the current state of water scarcity can be attributed to a failure of state control along with extreme climate changes 1. According to the climate change and the impact on sustainable water condition the population at risk is rapidly increasing with the rise of temperature in these regions that have arid and semi-arid condition compared to global averages [11]. For waterdistressed regions, global mean temperature increases above 1.5ºC is identified as an indicator for decrease in water supply and quality [11], supported by [10] which links decades of warming to increasing atmospheric water vapour content; changing precipitation patterns, intensity and extremes; reduced snow cover and widespread melting of ice; and changes in soil moisture and runoff. 3 Surface Water and Climate Change Impact on South Africa Surface water primarily comprises of water in the rivers, lakes, reservoirs and overland flow, while the unsaturated zone segment consist of that part of subsurface where the dense water from rainfall or leakage from runoff does not completely fill the voids in between the soil and rocks. The flow in case of unsaturated zone is normally downwards under influence of gravity, the relatively impermeable rock layers often hamper infiltration to layers below leading horizontal water flow that could release as seepage to the surface or streams. Such a flow of water is called interflow. Furthermore, the groundwater segment comprises the saturated zone which is recharged by the thorough water from rainfall and overlying water layers. Also there is the base flow which is formed by seepage from groundwater storage, particularly during extended drought periods sustaining streams. In cases where streams are often observed flowing even after it had long rained are mostly fed by springs and groundwater leakages. Fundamentally, South Africa is a semi-arid place with water scarcity. The region has witnesses only 9% of rainfall being converted to river runoff, the 9% would mean a mere 490mm rain which is half of world average rainfall. Studies from [13] reflect that rainfall in this region shows a decreasing trend and is highly variable between years and recurrent droughts. This trend has resulted in highly variable river level, storage level in dams and ground water level [15]. Referring to historic data we can see that majority of catchments use more water than is available on an annual basis [13]. The usage history and distribution of water coupled with the close relationship between climate change and hydrological cycle indicates that water resources and surface water availability will be affected by changing climate which will in turn increase the pressure on multiple resources, increasing the threat for water sustainability in future [14]. This is further supported by studies conducted by [16], indicating that ground water resources are directly influenced by climatic changes and so with increased climatic change these are under direct impact line. One of most serious impact of climate change is the change ISBN:

4 in intensity and frequency of rainfall which is the main source for major surface water reservoir. This would mean an even more variable availability of water which may be due to less ground water, increased demand and deteriorating water quality. According to [17], despite the level of consumption and threats due to climate change, by 2015 South Africa is expected to use majority of its surface water resources which will lead to sustainability concerns for surface water and hence its availability for future. [17] further indicates that the supply pressure will be driven or dominated by climate change along with environmental degradation and other pollution associated aspects. On the other hand the demand segment would be dominated by population influence, domestic demand, industrial requirement and most prominently the agricultural demand [17]. The next section is dedicated to understanding key factors that influence water availability in South Africa and would include a brief study of climate factors along with policy matters that impact water storage, distribution and management. The second section helps understand the key factors of climate change that influence surface water level, the historic details and upcoming trends of those factors. The third and final section will review the predicted impacts of climate change on South African water resources. 4 Key Factors Influencing Consumable Water Availability in South Africa Nature along with rate of growth impacts the quality and quantity of water, whether in terms of abstraction or discharge. Human activities like energy generation, agriculture and construction consume substantial amount of consumable water in developing countries putting huge pressure on the resources. For the region of South Africa, and its water sector to be specific, needs to align the terms of water with the spatial and sectoral growth of the economy. Similarly, the way economic changes impact the water resources, social change like migration put pressure on how these resources are to be managed for providing sustainable solution for growing needs. For the region, the policy making bodies and managers need to deal with a plethora of challenges that range from circular migration between rural and urban regions, increasing informal settlements on the outskirts of towns, and uncertainty about the amount of free basic water that could be provided to households and what options of services will meet the need of such households in the most effective manner [15]. Along with these there are other challenges like water storage, distribution and monitoring, treatment and waste water collection infrastructure that require serious consideration to keep up the efforts in the positive direction for meeting up the water requirements for the region of South Africa. Effective infrastructure is a key to maintain a sustainable water service and more importantly making an efficient use of water which will counteract many of the increased requirements for water lead by economic growth [15]. Further, the increased water demands from enhanced standards of living, increasing industrial and mining use, and failure of water and wastewater management infrastructure has considerable impact on water quality. Poor water quality can significantly impact social, health and economic conditions, as well as can negatively influence the aquatic ecosystems. Various institutional arrangements have been regularly changing since 1994, which complements the complexity of the aforementioned challenges as well as to approach in which the water sector responds to water needs for growth and development [15]. However, the National Water Act of 1998 has provided a new institutional framework for water management in South Africa and it is considered to be one of the most comprehensive examples of water legislation in the world. 5 Understanding Climate and Climate Change According to [11] climate change has been identified as a statistically significant variation in climate that persists for an extended period that usually ranges for decades or longer. The climate change normally includes a shift in the frequency and magnitude of weather events accompanied by a slow but constant increase in global surface temperature. This global increase in the surface temperature is one of the key contributors when it comes to surface water condition or more effective retention. A statistical depiction of weather of a region in terms of its mean and inconsistency of the identified parameters for example temperature and precipitation over an extended period, mostly around 30 years (as defined by the World Meteorological Organisation, WMO) is termed as climate of that region [18]. On the other hand, the climate system is composed of the atmosphere, ISBN:

5 hydrosphere, cryosphere, land surface and biosphere. Basically, the heat energy from the Sun is core driver of all changes associated climate system. The overall solar radiation must be counter balanced by an equal extent of radiation back into space to keep up a transitory balance between the incident and reflected solar radiation. However, this balance may get distorted by perturbations to the climate system. These influencing forces can be categorised into two processes as external processes and/or internal processes [1, 19]. 1. External Factors: These are natural forces and occur outside the climate system for example solar radiation and collisions of comets, these can contribute to the total natural variability in the climate system and are comparatively very long term of sudden in impact. 2. Internal Factors: These factors occur within the climate system and are associated with the natural process, like volcanic activity, atmospheric processes and are coupled with interactions between climatic mechanisms for example the El Niño. The internal factors occur instantaneously and are in constant engagement with other forces, an example of short time but continuous process is condensation of water vapour to form clouds, and long term which takes years would be inter-hemispheric exchange. However, the concern is more of human intervention and activities that cause disruption of these climatic factors or processes. For instance, deforestation and desertification alter land surface and hence lead to surface-albedo condition. The key concern is that human introduced factors are comparatively short in terms of time taken and can lead to much speedy climatic change and in worst case deterioration of climatic cycle which gradually leads to sudden climatic cycles that have negative impact on overall nature. Therefore, climate change is the result of these perturbations that persistently create variations in the mean and/ or variability of the climate properties in tune of an extended period (in terms of decades) [20]. This identification considers any change that is because of the natural variability of the climate system or anthropogenic activity. According to United Nations framework convention on climate change [21], climate change is an observed change that is comparable over identified periods and in composition of global atmosphere along with natural variability. This change is in conjunction with direct and indirect human activity. The primary greenhouse gases like methane, carbon dioxide and water vapour are naturally existing elements in the environment and they are responsible for keeping the earth arm. However, the main concern is the extended and rapid rate at which human activities are releasing these greenhouse gases into the environment including more potent halocarbons. Since these gases have long atmospheric life spans, it will be centuries before the climate system can recover from this damage. 6 Trends for Key Climatic Factors influencing Surface Water According to a study [22] conducted in year 2002 by a consortium of four South African universities, using a variable resolution model a probable future climate scenario was developed for the region of South Africa. The C-CAM model or the conformalcubic atmospheric model that is developed by the CSIRO (Commonwealth Scientific and Industrial Research Organisation) was used for the purpose and it has produced comparatively high spatial resolution, results that are best for impact analysis [22]. Using the CSIRO s Mk3 AOGCM for both models it simulated for early day climatic conditions for the period of by making use of observed CHG concentrations. However, it is to be noted that only A2 SRES scenario was used for the purpose of future climate predictions for the period of For this, the dataset of of from the climate research unit (CRU) was used so as to validate the present day simulation results from the conformal-cubic atmospheric model. The result had a consensus between the dataset in terms of rainfall and temperature with few variations intrinsic to using such models. According to simulations the temperature for southern African subcontinent is expected to go up from 1 degree Celsius to 3 degree Celsius with the western sub-continent predicted to be warmer than the eastern [22]. The rainfall is expected to reduce by 20 to 40% for the western and southern coastal regions of South Africa. The above observation and predictions are for the period of June, July and August. However, for quarter starting September there is difference in prediction as compared to earlier findings. An increase in rainfall is expected for the quarter starting September and has a range of 30 to 40%. Similarly, the central and ISBN:

6 eastern parts of the country are expected to receive increased rainfall by a margin of 20% for the period of December to January. Likewise the western interior is expected to witness an increase in amount of rainfall by a range of 10 to 20% for the period of February to April. It is evident from the above study that South Africa is expected to witness a warmer climate with serious variations in annual rainfall distributed over a period of time. However, to understand the results better we should isolate the two findings of temperature and rainfall (precipitation) and evaluate the historic and future expected trends concerning change in these contributing factors. 6.1 Temperature Historic Trend: Multiple studies indicate that the near surface temperatures have gone up by 0.5 C or even more during the last 50 to 100 years for most of Africa, with regions with minimum temperatures warming more rapidly than regions with maximum temperatures [23]. For the near surface air temperature that impacts surface water the most, variations in Africa were particularly higher for the period of as compared to the period of According to the data collected the mean annual temperature has increased over the past century for most of the African continent. Meanwhile, in recent years, the North African seasonal and annual near surface temperature trends indicate an overall warming which is particularly more than the range of changes as a result of natural variability Upcoming Trend According to new trends in the region, the temperature in Africa during 21 st century is expected to rise at a much faster rate than the rest of the globe [24]. However, for the tropical regions, in particular the tropical West Africa, the unprecedented level of climate change is projected to occur 1 to 2 decades in advance as compared to global average because of comparatively small natural climate variability in this region that generates a narrow climate hurdle which can be easily surpassed by relatively small climate changes. Also, Elevation in the mean annual temperature for the overall areas is very likely during the mid- to late 21st-century. For the region of North Africa, both the annual minimum and maximum temperature are expected to rise in the future, with the greater spike in minimum temperature [24]. According to [24], the comparative fast increase in temperature is consistent with higher temperature spike during night which will result in decrease of extreme temperature range. It is to be noted that the strengthening of the North African thermal low in 21st century is linked to surface temperature increase [25]. 6.2 Precipitation Historic Trend According to the precipitation trends and related data, most of the African continent does not have sufficient records to support a statistical analysis that could shed some light on annual precipitation trends for past century, moreover for many regions of the continent various discrepancies exist for the observed data sets [28]. Further, during the winter season many of the regions of North Africa, particularly the Atlas Mountains and the area of Mediterranean coast of Algeria along with Tunisia have significant records of decrease in annual rain fall [28]. The recorded data has also indicated that there has been a greater than 330 dry days with less than 1 mm day 1 rainfall for an extended period of [25]. However, compared to earlier findings for the quarter of September, October and November there have been positive trend in rain fall for various regions of northern Algeria and Morocco [27]. Overall the studies conclude that there have been significant variation in the precipitation and further the annual rain fall is decreasing for major areas of the African continent Upcoming Trend According to the upcoming trends the rain fall predictions are even more complicated and uncertain as compared to past history for the region. According to [29], the uncertainty in rain fall prediction exhibits a higher spatial and seasonal dependence compared to temperature projections. Studies suggest that a reduction in rainfall for the northern Africa is highly likely at the end of the 21st century. Similarly, the annual and seasonal dryness signal for the North African region (including North of Morocco, Algeria, Libya, Egypt, and Tunisia) is a constant feature in the global [27] and the regional climate change predictions for 21 st century [26]. 7 Conclusion The paper details account of different source of water that exist in the region of South Africa and what type of geological relation they share with ISBN:

7 environment and respective environmental changes. The paper explains multiple forms and sources of water availability with focus on surface water. The quality and availability of this source of water can have great influence due to climatic changes and evidence indicate that the impact on surface water get more dramatic when individual contributing factors for climate change are taken into consideration. It identified during the study that most of the changes in climatic condition are supplemented or rather we can say driven by human intervention and industrial activities. It is understood that respective climatic changes like temperature increase and precipitation level have always been on the horizon. However, human interventions have made those changes more radical and difficult to predict. Human activities are rated to have significant effects and while African countries have contributed little to the magnitude of the global problem they stand to bear some of the serious consequences. For this region the manifestations are not different and such events like floods, drought, sea-level rise, drying of river beds and change of quality and quantity of surface water are expected to increase for South Africa. There has been no conclusive report or finding that can link and drive the surface water level change and climatic conditions in major part of Africa because there are no proper resources and historic statistics that could drive this logic. However, the findings are still strong enough to indicate influence and motivate further studies in the direction of finding the strong relationship between climatic changes and surface water level in South Africa. Their effect in Africa is expected to increase, particularly as they co-exist with a range of other geological and human driven stress factors such as population growth, unequal access to resources, food insecurity, poor health systems and poverty. All these components will elevate the vulnerabilities of many people in Africa. Furthermore, the low capacity in science, technology and innovation will further deepen the susceptibility and influence of climate change on surface water resources. 8 Reference 1. Intergovernmental panel for climate change, United Nations Environment Programme, Hinrichsen, D., Robey, B., and Upadhyay, U.D. (1997) Solutions for a Water-Short World. Population Reports, Series M, No. 14. Baltimore, Johns Hopkins School of Public Health, Population Information Program, Maryland, United States. Available at: ml 4. Gleick, P The World s Water: The Biennial Report on Freshwater Resources (Island Press. Washington DC). 5. Charles J. Vörösmarty, Ellen M. Douglas, Pamela A. Green and Carmen Revenga Geospatial Indicators of Emerging Water Stress: An Application to Africa. Ambio. 34, (3), WBGU, Bremerhaven. German Advisory Council on Global Change, WBGU (1998) World in Transition: Ways Towards Sustainable Management of Freshwater Resources. Report Springer, Berlin, Heidelberg, New York 7. German Advisory Council on Global Change World in Transition: Fighting Poverty through Environmental Policy. London: Earthscan. 8. Lonergan, S. (2003) Water and War. Division of Early Warning and Assessment, UNEP. 9. Anyadike, R.N.C. (2009) Climate change and sustainable development in Nigeria: Conceptual and empirical issues. Debating Policy Options for National Development; Enugu Forum Policy Paper 10; African 10. Bates, B. C., Kundzewicz, Z. W., Wu, S., & Palutikof, J. P Climate change and water. Technical paper of the Intergovernmental Panel on Climate Change (IPCC). Geneva: IPCC Secretariat. 11. United Nations Educational, Scientific and Cultural Organization, UNESCO (2003) The UN World Water Development Report. Water for People, Water for Life. World Water Assessment Programme. UNESCO, New York 12. Intergovernmental Panel on Climate Change, IPCC, (TAR) (2001) Third Assessment Report (TAR) of the Intergovernmental Panel on Climate Change. Parts 1, 2 and 3, Synthesis Report and Policy Makers Summaries. Cambridge University Press, Cambridge, UK. 13. DWAF (Department of Water Affairs and Forestry) DRAFT Water conservation and demand management strategy for the water services sector. 14. DWAF, Water Management Areas. ISBN:

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