CHAPTER ONE

INTRODUCTION

1.1 BACKGROUND OF STUDY

Water is indispensable for life, but its availability at a sustainable quality and quantity is threatened by many factors, of which climate plays a leading role (IPCC, 1995). Groundwater is the major source of drinking water in Africa and has a rapidly expanding role in irrigation to combat growing food insecurity. This module deals with both the impact of climate change on groundwater resources, It is important to recall the global extent of climate change, and to consider the impacts on the scale of the global hydrologic cycle.

Of Africa’s population of 1 billion, roughly 60% live in rural areas. Around 80% of them rely on groundwater-based community or household supplies for domestic and other water needs (WHO/UNICEF, 2008). Currently there are more than 300 million people in Africa without access to safe drinking water, many of whom are amongst the poorest and most vulnerable in the world (MacDonald, A.; Bonsor, H.C.; Dochartaigh, B.E.O.; Taylor, R.,, 2012). Climate variability and change influences groundwater systems both directly through replenishment by recharge and indirectly through changes in groundwater use. These impacts can be modified by human activity such as land-use change (Taylor, Nature Climate change, 2013).

Climate change is “an altered state of the climate that can be identified by change in the mean and/or variability of its properties and that persists for an extended period, typically decades or longer”. It may be due to “natural internal processes or external forcing, or to persistent anthropogenic changes in the composition of the atmosphere or in land use” (IPCC, 2007).

Climate change affects water resources around the world in generally unknown ways. Potential impacts of climate change on surface water particularly projected regional climate patterns and trends (i.e., climate variability and change) have been studied in some detail. Yet, little is known about how subsurface waters will respond to climate change coupled with human activities

We refer to all subsurface water as ‘‘groundwater’’, including soil water and unconfined and confined aquifer waters. Distinctions can be made between these components of groundwater, noting interactions between them and surface water.

The challenges of understanding climate-change impact on groundwater are unprecedented because climate change may affect hydrogeological processes and groundwater resources directly and indirectly (Allen, D. M., Mackie, D. C., Wei, M., 2004). In ways that have not been explored sufficiently

Observational data and climate predictions provide abundant evidence that freshwater resources (both surface and groundwater resources) are vulnerable and have the potential to be strongly affected by climate change, with wide-ranging consequences for society and ecosystems (Calow, R.; MacDonald, A, 2009).

Today, climate change may account for approximately 20% of projected increases in water scarcity globally (Bouraoui, F., Vachaud, G., Li, L. Z. X., Le Treut, H,, Chen, T., 1999).

Thus, there is a need to evaluate and understand climatic variability over the long term to better plan and manage groundwater resources well into the future, while taking into consideration the increasing stresses on those resources from population growth and industrial, agricultural, and ecological needs (Warner, S.D., 2007).

In this project we appraise the state of the science of global change related to all components of groundwater. Scientific issues and methods are placed in the context of global programs aimed at assessment of groundwater resources and adaptation to climate change. The current emphasis is on regional case studies with the potential for global analogues to inform decisions where detailed studies are not presently feasible. In this synthesis of results to date, we provide the type of soft information needed to generalize scientific knowledge and the controlling factors specific to each case study.

1.2 STATEMENT OF THE PROBLEM

 Abundant evidence exists that water resources are vulnerable to the effects of climate change. Climate change effects on surface-water resources are widely recognised but not much is known about climate change effects on groundwater resources. Subsurface hydrology is intimately coupled with surface hydrology and atmosphere; the responses of groundwater hydrology to climate change have been assessed. Contemporary groundwater and climate systems are not in equilibrium due to the long memory of deep groundwater system with long flow part and large storage. Changes in climate have implications for groundwater quantity and quality in many aquifers; the responses of aquifer recharge, discharge and changes in storage to climate change are assessed on inter-annual to multi-decadal or longer geologic time scales. Groundwater resources are vulnerable to changes in storage due to variability in precipitation patterns, evapotranspiration, fluctuations in surface-water and groundwater interactions, and over withdrawer arising from climate change.

1.3 OBJECTIVE OF THE STUDY

The main objective of the study is to investigate the impact of climate change on groundwater by studying climate parameters of soil and atmosphere. The specific objectives include

1 To determine the  nature and significance of groundwater

2 To determine the nature and effect of climate change on groundwater.

1.4 RESEARCH QUESTIONS

1 What is the nature and significance of groundwater?

2 What is the nature and effect of climate change on groundwater.

1.5 SIGNIFICANCE OF THE STUDY

 A deeper understanding of the effects of climate change on groundwater resources over long term is integral for better planning and efficient groundwater management. Information about climate related effects on groundwater resources is inadequate, especially with respect to groundwater quality and ecosystems, and socio-economic dimension. Climate induced changes in hydrological variables and their impacts on groundwater systems are limited by uncertainties

1.6 SCOPE OF THE STUDY

The study focuses on the appraisal of the  impact of climate change on groundwater by studying climate parameters of soil and atmosphere

1.7   LIMITATION OF THE STUDY

The study was confronted by logistics and geographical constraint

1.8 DEFINITION OF TERMS

CLIMATE DEFINED

Climate is commonly defined as the weather averaged over a long period. The standard averaging period is 30 years, but other periods may be used depending on the purpose. Climate also includes statistics other than the average, such as the magnitudes of day-to-day or year-to-year variations.

CLIMATE CHANGE DEFINED

Climate change is the variation in global or regional climates over time. It reflects changes in the variability or average state of the atmosphere over time scales ranging from decades to millions of years. These changes can be caused by processes internal to the Earth, external forces (e.g. variations in sunlight intensity) or, more recently, human activities. In recent usage, especially in the context of environmental policy, the term "climate change" often refers only to changes in modern climate, including the rise in average surface temperature known as global warming. In some cases, the term is also used with a presumption of human causation, as in the United Nations Framework Convention on Climate Change (UNFCCC). The UNFCCC uses "climate variability" for non-human caused variations. normal, separated by interglacial periods. The accumulation of snow and ice during a glacial period increases the surface albedo, reflecting more of the Sun's energy into space and maintaining a lower atmospheric temperature. Increases in greenhouse gases, such as by volcanic activity, can increase the global temperature and produce an interglacial period. Suggested causes of ice age periods include the positions of the continents, variations in the Earth's orbit, changes in the solar output, and volcanism.

GROUNDWATER  DEFINED

Groundwater may be regarded as all forms of water in the subsurface; this includes water in the soil root zone (soil moisture), deeper vadose zone and saturated zone (confined and unconfined aquifers

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