**1. Introduction**

76 Studies on Water Management Issues

consists of impermeable wall situated along surface flow, which is dropped to the neogene. Artificial groundwater body feeding, which results from integrated surface and groundwater utilization and long lasting sub-surface accumulation, is preferred where it is possible. Artificial feeding has important role by repeated water utilization, because it gives also quality advantages (water clarifying in soil and in groundwater bodies). In order to utilize the underground reservoir for the storage of significant water amount with the intention to utilize it in later period, it is necessary to discover potential accumulation capacity of the groundwater reservoir as well as its convenience for feeding from surface water and easy pumping in the case of necessity. Groundwater reservoir should show sufficient free space between surface terrain and groundwater level for the water storage and water reservation from feeding during the period when the water is not necessary.

Author would like to express thanks to the Grant Agency of Slovak Academy of Sciences

Anderson, M.P. & Woessner, W.W. (1992) *Applied groundwater modelling*. Academic press,

Duba, D. (1964) Solution of changes in groundwater level caused by Nagymaros dam construction. *Geologické práce*, Zprávy 32, Bratislava, pp. 91-104 (In Slovak) Gomboš, M. (2008). Water storage dependability in root zone of soil. *Cereal Research* 

Chiang, W.H. & Kinzelbach W. (2001) *3D-Groundwater Modelling with PMWIN. A Simulation* 

Konikow, L.F., & Bredehoeft, J.D. (1978) Computer model of two-dimensional solute

McDonald, M.G. & Harbaugh A.W. (1988) *A modular 3-D finite difference groundwater flow model*. USGS, U.S. Geological Survey Open-File Report 83-875, Book 6 Mucha, I. & Šestakov, V.M. (1987) *Groundwater Hydraulics*. ALFA-SNTL, Bratislava-Praha (In

Silva, W.P. & Silva, C.M.D.P.S. (1999-2010) LAB Fit Curve Fitting Software (Nonlinear

Šoltész, A. & Baroková, D. (2004) Analysis, prognosis and control of groundwater level

*System for Modelling Groundwater Flow and Pollution*, Springer-Verlag Berlin

transport and dispersion in groundwater.U.S. Geological Survey Techniques of

Regression and Treatment of Data Program) V 7.2.47 online, available from

regime based on means of numerical modelling. In: *Global Warming and other Central European Issues in Environmental Protection: Pollution and Water Resources*, Columbia University Press, Vol.XXXV, Columbia, pp.334-347, ISBN 80-89139-06-X Velísková, Y. (2010) Changes of water resources and soils as components of agro-ecosystem in Slovakia. *Növénytermelés*, Vol. 59, suppl., pp. 203-206, ISSN 0546-8191

VEGA for the financial support from projects No 2/0123/11 and No 2/0130/09.

*Communications,* Vol.36, No.1, pp. 1194-1194, ISSN 0133-3720

Water-Resources Investigations, Book 7, chap. C2, 90 p.

**7. Acknowledgment** 

Inc., California

Slovak.)

http:/www.labfit.net

http://www.gabcikovo.gov.sk

Heidelberg, ISBN 3-540-67744-5

**8. References** 

Groundwater has long been and continues to serve as a reliable source of water for a variety of purposes, including industrial and domestic uses and irrigation. The use of generally high-quality groundwater for irrigation dwarfs all other uses (Burke, 2002); and there are a number of aspects of water quality that have to be managed in such circumstance (e.g salinity, Sodium Absorption Ratio, nutrients, depending on the circumstances of the irrigation). As such there is the need to understand the various implications for use in the management of groundwater resources.

Effective management of groundwater is highly dependent on appropriate reliable and upto-date information (Adelana, 2009) as may be contained in a groundwater database (GDB). According to FAO (2003a), there are currently thousands of local and personal databases storing key technical and licensing data in a very unsatisfactory manner (mostly in terms of usable formats). Hence, the hard evidence required for the assessment of global trends in groundwater depletion and aquifer degradation is still lacking. It is therefore difficult to assess the extent to which global food production could be at risk from either overabstraction or from groundwater quality deterioration.

A study on groundwater and food security conducted by FAO (2003a) revealed that compiling reliable groundwater-level and abstraction data (to determine depletion rates) was fraught with problems of coverage, consistency and reliability. Therefore obtaining reliable time-series data on groundwater levels in specific aquifers in many countries may be key to assessing global trend and invariably future impact on food security. The complete lack of a GDB is seriously constraining the formulation and implementation of effective groundwater management policies in many countries. This reinstates the importance of consistency and reliability of groundwater level monitoring for effective groundwater management. In order to ensure sustainable management groundwater level responses must be considered in relation to climate changes and in response to increased agricultural food production.

In the context of varying climatic conditions and frequent lower than average annual rainfall, observed groundwater responses vary and subsequently reduce recharge, stream flow, and the water balance. For example, over the last ten years, decrease in rainfall amount

Changes in Groundwater Level Dynamics in Aquifer Systems –

groundwater identified (Adelana & Xu, 2006).

occurs in summer (Adelana, 2011).

station in Laverton near Werribee).

**3. Study approach** 

Implications for Resource Management in a Semi-Arid Climate 79

groundwater users and licensed volumes are encoded onto WARMS (Water use And Registration Management System section of DWA) database. In practise, the farmers in the Cape Town area irrigate their crops, particularly during the dry summer months and intensely in drier years. As at December 2006, the highest single registered volume was 699.15 ML/yr (Adelana, 2011). From WARMS record in 2006, there were 211 bores used for agriculture, 25 for industry and two for water supply within the City of Cape Town municipality (although a number of unregistered household bores may exist). The City of

In the WID, expected threats to the aquifer include seawater intrusion from the coastline and estuarine portion of the Werribee River, inter-aquifer transfer of saline groundwater, and water level-induced bore failure. Reduced rainfall conditions exacerbate these threats by reduced recharge from both rainfall and channel leakage, increased estuarine length of the Werribee River, and an increased dependency on groundwater (SRWA, 2009). In the Cape Flats aquifer the maximum extent of seawater intrusion into the Cape Flats aquifer has been estimated to be approximately 1,000 m from the coastline (Gerber 1981), although recent studies (Adelana, 2011; Adelana & Xu, 2006) did not confirm inland saltwater movement. Nevertheless, surface water in the Cape Flats is known to be contaminated from various sources (Usher et al., 2004; Adelana & Xu, 2006) and the potential treat to

Within the WID, the highest percentage of groundwater extraction is from the Werribee deltaic sediments. Regions of the deltaic aquifer adjacent to the coastline and estuary have exhibited depressed watertable conditions, with hydraulic heads falling below mean sea level and/or at lowest recorded levels. These regions are also exhibiting rising groundwater salinity, particularly in deeper piezometers (SRWA, 2009). In the Western Cape, agricultural sector is one of the largest users of water resources; but rapid economic development and population growth is also generating increased pressure on water supplies. For example, the growth in urban water demand in the Greater Cape Town Metropolitan Area was projected to increase from 243 million m3 in 1990 to 456 million m3 in 2010; whereas for irrigation water demand the increase is from 56 million m3 in 1991 to 193 million m3 in 2010 (Ninham Shand, 1994). Over 60 % of the annual urban demand and 90 % of the irrigation demand

In order to investigate varying climatic conditions and the impact of frequent lower than average annual rainfall on observed groundwater levels the long-term climate data are analysed and compared for both study areas. In the long-term, rainfall, minimum and maximum temperatures are related to climate variability. The climate data obtained were analysed and statistically interpreted. Long-term data are from the South African Weather Service (Station: Cape Town Observatory/Airport) and Bureau of Meteorology (BOM with

The groundwater databases of the Department of Primary Industries (DPI) and Department of Sustainability and Environment (DSE) Groundwater Management System (GMS) were examined to select representative bores tapping the Werribee Delta aquifer. Also, from the National Groundwater Database (NGDB) managed by DWA, a few bores screened in the

Cape Town has water restriction and management plan in place since 2002.

and rain intensity has been the major factor responsible for the declining groundwater levels across northern Victoria in SE Australia (Reid, 2010; Reid et al., 2007). The prolonged effects are expected to contribute a negative impact on water security, agricultural production and the ecosystem. However, under conditions of reduced groundwater use (with recycled water or inter-catchment water transfer), the impacts of irrigated agriculture on the hydrodynamics of shallow aquifer systems and the quality of the groundwater will also need to be fully quantified. Such impacts have been witnessed in other groundwater systems across Australia (Giambastiani et al., 2009; Kelly et al., 2009; McLean & Jankoski, 2002; McLean et al., 2000; Schaffer & Pigois, 2009) and elsewhere in the world (Abidin et al., 2001; Adelana et al., 2006a, 2006b; Chai et al., 2004; Hotta et al., 2010; Lopez-Quiroz et al. 2009).

This study demonstrates the importance of consistent groundwater level monitoring in relation to (and its implications on) effective and sustainable resource management as well as improved the understanding of climate impacts on groundwater levels. Two case examples are selected from areas at different level of groundwater monitoring, used to illustrate impact of climate variability as well as the importance of reliable and consistent groundwater monitoring database.

#### **2. Background**

Water use in both study areas (the Werribee Plains, Western Melbourne metropolitan, South-east Australia (Figure 1) and the Cape Flats, Cape Town metropolitan area, South Africa (Figure 2)) supports year-round irrigation, and is one of conjunctive use, including a channel network fed by releases from reservoirs and recycled water, respectively, and supplementary groundwater extractions. This represents two long established irrigation districts: the Werribee Irrigation District (WID) and the Cape Flats farming areas, both known for their market gardens. At a national scale, the WID is major suppliers of lettuce, cabbage, broccoli and cauliower (SRWA, 2009), while the Cape Flats, especially the Greater Philippi horticultural area, is an important source of Cape Town's fresh produce (such as lettuce, onions, fresh fruit, bananas, potatoes) and which, at the regional scale produces 70- 80% of vegetable sold in the Greater City of Cape Town (Rabe 1992, CCT 2010). For the two areas, the location, the highly productive soils and intensive cropping capability allow for diverse production and all-year-round supply. Moreover the close proximity of the two farming areas to fast growing commercial centres (Melbourne and Cape Town, respectively) provide market advantages and increases the value of the land for urban development.

Active groundwater management of the system in the Werribee Plains was initiated in 1998, at which time a safe yield of 2,400 ML/yr was estimated, compared to the sum of licensed groundwater extraction about 6,000 ML/yr. The installation of meters on all licensed bores occurred in 2004. A 25% restriction in licensed volume was in place (SKM, 2004) and this has since been regularly reviewed. Southern Rural Water Authority (SRWA) is the responsible agency for the management of groundwater resources in this district. Until recently, irrigators have been able to consistently rely on approximately 10,000 ML of water rights from SRWA's water distribution system (predominantly concrete-lined channels) and 5,000 ML of groundwater licences in the underlying shallow Groundwater Management Area (Rodda & Kent, 2004). In the Cape Flats, the Department of Water Affairs (DWA) is responsible for permits, licensing and metering. All information regarding registered

and rain intensity has been the major factor responsible for the declining groundwater levels across northern Victoria in SE Australia (Reid, 2010; Reid et al., 2007). The prolonged effects are expected to contribute a negative impact on water security, agricultural production and the ecosystem. However, under conditions of reduced groundwater use (with recycled water or inter-catchment water transfer), the impacts of irrigated agriculture on the hydrodynamics of shallow aquifer systems and the quality of the groundwater will also need to be fully quantified. Such impacts have been witnessed in other groundwater systems across Australia (Giambastiani et al., 2009; Kelly et al., 2009; McLean & Jankoski, 2002; McLean et al., 2000; Schaffer & Pigois, 2009) and elsewhere in the world (Abidin et al., 2001; Adelana et al., 2006a, 2006b; Chai et al., 2004; Hotta et al., 2010; Lopez-Quiroz et al.

This study demonstrates the importance of consistent groundwater level monitoring in relation to (and its implications on) effective and sustainable resource management as well as improved the understanding of climate impacts on groundwater levels. Two case examples are selected from areas at different level of groundwater monitoring, used to illustrate impact of climate variability as well as the importance of reliable and consistent

Water use in both study areas (the Werribee Plains, Western Melbourne metropolitan, South-east Australia (Figure 1) and the Cape Flats, Cape Town metropolitan area, South Africa (Figure 2)) supports year-round irrigation, and is one of conjunctive use, including a channel network fed by releases from reservoirs and recycled water, respectively, and supplementary groundwater extractions. This represents two long established irrigation districts: the Werribee Irrigation District (WID) and the Cape Flats farming areas, both known for their market gardens. At a national scale, the WID is major suppliers of lettuce, cabbage, broccoli and cauliower (SRWA, 2009), while the Cape Flats, especially the Greater Philippi horticultural area, is an important source of Cape Town's fresh produce (such as lettuce, onions, fresh fruit, bananas, potatoes) and which, at the regional scale produces 70- 80% of vegetable sold in the Greater City of Cape Town (Rabe 1992, CCT 2010). For the two areas, the location, the highly productive soils and intensive cropping capability allow for diverse production and all-year-round supply. Moreover the close proximity of the two farming areas to fast growing commercial centres (Melbourne and Cape Town, respectively) provide market advantages and increases the value of the land for urban development.

Active groundwater management of the system in the Werribee Plains was initiated in 1998, at which time a safe yield of 2,400 ML/yr was estimated, compared to the sum of licensed groundwater extraction about 6,000 ML/yr. The installation of meters on all licensed bores occurred in 2004. A 25% restriction in licensed volume was in place (SKM, 2004) and this has since been regularly reviewed. Southern Rural Water Authority (SRWA) is the responsible agency for the management of groundwater resources in this district. Until recently, irrigators have been able to consistently rely on approximately 10,000 ML of water rights from SRWA's water distribution system (predominantly concrete-lined channels) and 5,000 ML of groundwater licences in the underlying shallow Groundwater Management Area (Rodda & Kent, 2004). In the Cape Flats, the Department of Water Affairs (DWA) is responsible for permits, licensing and metering. All information regarding registered

2009).

groundwater monitoring database.

**2. Background** 

groundwater users and licensed volumes are encoded onto WARMS (Water use And Registration Management System section of DWA) database. In practise, the farmers in the Cape Town area irrigate their crops, particularly during the dry summer months and intensely in drier years. As at December 2006, the highest single registered volume was 699.15 ML/yr (Adelana, 2011). From WARMS record in 2006, there were 211 bores used for agriculture, 25 for industry and two for water supply within the City of Cape Town municipality (although a number of unregistered household bores may exist). The City of Cape Town has water restriction and management plan in place since 2002.

In the WID, expected threats to the aquifer include seawater intrusion from the coastline and estuarine portion of the Werribee River, inter-aquifer transfer of saline groundwater, and water level-induced bore failure. Reduced rainfall conditions exacerbate these threats by reduced recharge from both rainfall and channel leakage, increased estuarine length of the Werribee River, and an increased dependency on groundwater (SRWA, 2009). In the Cape Flats aquifer the maximum extent of seawater intrusion into the Cape Flats aquifer has been estimated to be approximately 1,000 m from the coastline (Gerber 1981), although recent studies (Adelana, 2011; Adelana & Xu, 2006) did not confirm inland saltwater movement. Nevertheless, surface water in the Cape Flats is known to be contaminated from various sources (Usher et al., 2004; Adelana & Xu, 2006) and the potential treat to groundwater identified (Adelana & Xu, 2006).

Within the WID, the highest percentage of groundwater extraction is from the Werribee deltaic sediments. Regions of the deltaic aquifer adjacent to the coastline and estuary have exhibited depressed watertable conditions, with hydraulic heads falling below mean sea level and/or at lowest recorded levels. These regions are also exhibiting rising groundwater salinity, particularly in deeper piezometers (SRWA, 2009). In the Western Cape, agricultural sector is one of the largest users of water resources; but rapid economic development and population growth is also generating increased pressure on water supplies. For example, the growth in urban water demand in the Greater Cape Town Metropolitan Area was projected to increase from 243 million m3 in 1990 to 456 million m3 in 2010; whereas for irrigation water demand the increase is from 56 million m3 in 1991 to 193 million m3 in 2010 (Ninham Shand, 1994). Over 60 % of the annual urban demand and 90 % of the irrigation demand occurs in summer (Adelana, 2011).
