Santos, Isaac Rodrigues dos; Niencheski, Luis Felipe Hax; Burnett, William; Peterson, Richard; Chanton, Jeffrey; Andrade, Carlos Francisco Ferreira de; Milani, Idel Cristina Bigliardi; Schmidt, Axel; Knoeller, Kay
Fonte: Universidade Federal do Rio GrandePublicador: Universidade Federal do Rio Grande
We investigated the distribution of naturally occurring geochemical tracers (222Rn, 223Ra, 224Ra, 226Ra, CH4, d18O, and d2H) in the water column and adjacent groundwater of Mangueira Lagoon as proxies of groundwater discharge. Mangueira Lagoon is a large (90 km long), shallow (_4???5 m deep), fresh, and non-tidal coastal lagoon in southern Brazil surrounded by extensively irrigated rice plantations and numerous irrigation canals. We hypothesized that the annual, intense irrigation for rice agriculture creates extreme conditions that seasonally change groundwater discharge patterns in the adjacent lagoon. We further supposed that dredging of irrigation canals alters groundwater fluxes. While the activities of 222Rn in shallow groundwater were 2???3 orders of magnitude higher than in surface water, CH4 and radium isotopes were only _1 order of magnitude higher. Therefore, 222Rn appears to be the preferred groundwater tracer in this system. Radon concentrations and conductivities were dramatically higher near the pump house of rice irrigation canals, consistent with a groundwater source. Modeling of radon inventories accounting for total inputs (groundwater advection, diffusion from sediments, and decay of 226Ra) and losses (atmospheric evasion...
India is the largest groundwater user in
the world, with an estimated usage of around 230 cubic
kilometers per year, more than a quarter of the global
total. With more than 60 percent of irrigated agriculture
and 85 percent of drinking water supplies dependent on it,
groundwater is a vital resource for rural areas in India.
Reliance of urban and industrial waste supplies on
groundwater is also becoming increasingly significant in
India. Through the construction of millions of private
wells, there has been a phenomenal growth in the
exploitation of groundwater in the last five decades. The
potential social and economic consequences of continued weak
or nonexistent groundwater management are serious, as
aquifer depletion is concentrated in many of the most
populated and economically productive areas. The
implications are disturbing for attainment of the millennium
development goals, for sustaining economic growth and local
livelihoods, and for environmental and fiscal
sustainability. The consequences will be most severe for the
When a groundwater basin is exploited by
a large number of farmers, acting independently, each farmer
has little incentive to practice conservation that would
primarily benefit other farmers. This can lead to excessive
groundwater extraction. When farmers pay less than the full
cost of electricity used for groundwater pumping, this
problem can be worsened; while the problem can be somewhat
relieved by rationing the electricity supply. The research
in this paper constructs an analytical framework for
describing the characteristics of economically efficient
groundwater management plans, identifying how individual
water use decisions by farmers collectively depart from
efficient resource use, and examining how policies related
to both water and electricity can improve on the efficiency
of the status quo. It is shown that an optimal scheme for
pricing electricity used for pumping groundwater includes
two main elements: 1) the full (marginal) economic cost of
electricity must be covered; and 2) there must be an extra
Conjunctive water use refers to
simultaneous use of surface water and groundwater to meet
crop demand. This Note concludes that to optimize
conjunctive use of water, the best way forward is to
concentrate on capacity building of irrigation system
managers to improve system management and reshape hydraulic
infrastructure of large and small-surface systems. To
sustain groundwater use in tube well-irrigated areas,
enhancing recharge from precipitation and surface water
imports is necessary. None of these improvements can be made
without the proper institutional and organizational
development, including investment in the capacities of local
governments to lead on participatory groundwater management
and integrated water resources management.
Groundwater is playing an increasingly
important role in domestic, industrial and agricultural
water supply. With the advent of the tube well and driven by
the rapid growth of demand for agricultural and municipal
water, annual global groundwater extraction has increased in
recent decades from 100 k
South Florida has transformed from a natural to a managed ecosystem upon channelization of Kissimmee River and the wetlands in the 1960’s. The drainage has resulted in fast transport of water and nutrient, and subsequently eutrophication of the downstream water bodies. The intervention required: intensive management of the shallow groundwater to balance ecological water requirement; and nutrient removal, namely phosphorus, to minimize eutrophication.
The study was set to examine and develop an operational prediction method for groundwater-phosphorus interactions to support the wetlands management. Accordingly, a point scale and a spatio-temporal groundwater level was simulated using sequence based Markovian stochastic analysis and dynamic factor analysis methods respectively. A root mean square error of 0.12m and 0.15m was observed for a point and spatio-temporal groundwater prediction.
Soluble and sequestered phosphorus were also simulated at 13% error using a watershed based model called ArcWAM. A spatial analysis on simulated soluble phosphorus and groundwater level indicated similarity of patterns (spatial correlation) 99% of the time. A geographically weighted multivariate analysis of soluble phosphorus using predictors of groundwater level...
The interaction between groundwater and surface water systems is a key component of the hydrological cycle and an understanding of their connectivity is fundamental for sustainable water resource management. Water is a vehicle for mobilising dissolved constituents, including nutrients, between surface and subsurface waters and between terrestrial and marine systems.
Therefore, knowledge of surface-subsurface linkages is critical not only for water quantity allocation, but also for water quality and its implications for ecosystem health. In particular, ascertaining the significance of groundwater fluxes for river nitrogen budgets is an important motivation for characterising river-groundwater connectivity. This overarching theme is developed through the course of the thesis.
The marked seasonality of tropical river systems provides a unique opportunity to investigate groundwater contributions to surface waters, especially when there are minimal overland flows.
The Herbert River in northeast Queensland represents a useful case study in the Australian tropics for assessing the potential for transport of agricultural contaminants, such as dissolved forms of nitrogen, between surface and subsurface waters, and between terrestrial and marine systems...
In many parts of the world, access to groundwater is needed for domestic, agricultural and industrial uses, and global groundwater exploitation continues to increase. The significance of groundwater in maintaining the health of rivers, streams, wetlands and associated vegetation is often underestimated or ignored, resulting in a lack of scrutiny of groundwater policy and management. It is essential that management of groundwater resources considers the needs of natural ecosystems, including subterranean. We review the limited Australian literature on the ecological impacts of groundwater overdraft and place Australian information within an international context, focusing on lentic, lotic, stygobitic and hyporheic communities as well as riparian and phreatophytic vegetation, and some coastal marine ecosystems. Groundwater overdraft, defined as abstracting groundwater at a rate which prejudices ecosystem or anthropocentric values, can substantially impact natural communities which depend, exclusively or seasonally, on groundwater. Overdraft damage is often underestimated, is sometimes irreversible, and may occur over time scales at variance to those used by water management agencies in modelling, planning and regulation. Given the dangers of groundwater overdraft...
Riparian environments have degraded world-wide as a consequence of human development and climatic change. The native floodplain tree communities of semi-arid river systems are under stress from reduced flooding frequencies as a consequence of water extractions, river regulation and climate change. In regions with saline aquifers, river regulation and land management have also caused soil salinisation, further impacting on floodplain tree health. The lower River Murray in south-eastern Australia is a major ecological asset considered as an area of international significance. The dominant floodplain vegetation is suffering severe decline in health, with approximately 80% of floodplain trees reported as being in poor condition or dead. A reduction in water availability from reduced flooding and soil salinisation, has been identified as the primary cause. This has resulted from large irrigation extractions across the Murray-Darling Basin and elevated saline groundwater levels due to river regulation and land clearance. Management of these ecosystems needs to address both surface and groundwater changes. Increasing flooding regimes from environmental flow management and lowering of groundwater in regions of shallow saline aquifers are the most common scenarios adopted world-wide. Traditionally the assessment of management options for floodplain habitats has focussed on changes in river flow with no consideration given to surface water and groundwater interactions. In addition groundwater has been treated as a single homogenous unit. Wide floodplains have high spatial variability of habitats due to historic meandering anabranch creek systems that cause changing elevations and soil types. This in turn creates a highly variable pattern of surface and groundwater interactions. This thesis investigates the major causes of floodplain tree decline and develops methods for predicting the spatial impacts on floodplain tree health from a range of management scenarios. Surface and groundwater changes are often highly inter-connected but are usually considered separately at regional scales because of the complexity of management and modelling of surface and groundwater interactions over large areas. This thesis addresses the surface and groundwater changes at the regional scale of the lower River Murray. A floodplain inundation model for the River Murray (RiM-FIM) is developed to predict the extent of flooding at various magnitudes of flow and river regulation and a ‘drought index’ was used to indicate the risk to floodplain tree health of changing flow regimes. A floodplain impacts model (FIP) was applied spatially to predict groundwater discharge onto the floodplain and model vegetation risk. At the floodplain scale...
The growing population of the city of Lucknow, India has resulted in an increased water demand which is met by enormous groundwater withdrawal, with the consequences of fast depletion of water resources. The current study aims at implementing a sustainable pumping rate (SPR) concept to calculate groundwater extractions at different wells across the city and the pre-assessment of any artificial groundwater recharge scheme to be implemented in the city.
The SPR concept used in previous studies are used in different ways without actually addressing the principal components of water budget changes, due to groundwater extraction. In this study the groundwater extraction rates were calculated by maximizing the total extraction at all wells, subject to constraints with regards to socially and environmentally relevant measures which were similar or same while accounting for the water budget terms. The constraints were varied to find different groundwater extractions, by developing a groundwater model and coupling it with an optimization code. The analysis of resulting different groundwater extractions illustrates the wells to be preferred and avoided for groundwater extraction. An analysis of the sum of the groundwater extraction rates and corresponding values of constraints showed that the higher values of either of the constraints have resulted
in the same amount of total groundwater extraction...
Groundwater comprises 97 percent of the
worlds readily accessible freshwater and provides the rural,
urban, industrial and irrigation water supply needs of 2
billion people around the world. As the more easily accessed
surface water resources are already being used, pressure on
groundwater is growing. In the last few decades, this
pressure has been evident through rapidly increasing pumping
of groundwater, accelerated by the availability of cheap
drilling and pumping technologies and, in some countries,
energy subsidies that distort decisions about exploiting
groundwater. This accelerated growth in groundwater
exploitation unplanned, unmanaged, and largely invisible has
been dubbed by prominent hydro geologists the silent
revolution. It is a paradox that such a vast and highly
valuable resource which is likely to become even more
important as climate change increasingly affects surface
water sources has been so neglected by governments and the
development community at a time when interest and support
for the water sector as a whole is at an all-time high. This
case study is a background paper for the World Bank economic
and sector analysis (ESW) entitled too big to fail: the
paradox of groundwater governance that aims to understand
and address the paradox at the heart of the groundwater
governance challenge in order to elevate the need for
investing in and promoting proactive reforms toward its
management. The project examines the impediments to better
governance of groundwater...
This report presents a case study on
groundwater governance in Kenya. The objectives of the study
were to: (a) describe groundwater resource and socioeconomic
settings for four selected aquifers; (b) describe governance
arrangements for groundwater management in Kenya; and (c)
identify the relevance of these arrangements for planning
and implementing climate change mitigation measures. The
report provides a comprehensive strategy to develop
effective groundwater management and a pilot groundwater
management plan. Kenya's draft Policy for the
Protection of Groundwater provides most of the requirements
for improving groundwater governance, including
participation and empowerment of groundwater users,
decentralization of management to local level, integration
of surface and groundwater management, improving monitoring
and data collection, identifying sites for managed aquifer
recharge (MAR), mapping strategic aquifers and conjunctive
use opportunities, and identifying groundwater conservation
areas. Groundwater management decision making is
sector-based and on the whole ad hoc; there is no mechanism
for coordination and for fostering cross-sector linkages.
This publication provides guidance to
water-sector decision makers and planners on how to deal
with the quality dimension of groundwater resources
management in the World Bank's client countries. There
is growing evidence of increasing pollution threats to
groundwater and some well-documented cases of irreversible
damage to important aquifers. This guide has been produced
in the belief that groundwater pollution hazard assessment
must become an essential part of environmental best practice
for water supply utilities. The guide is particularly
relevant for the World Bank's Latin American and
Caribbean Region, where many countries have initiated major
changes to modernize their institutional and legal framework
for water resources management, but may not yet have
considered groundwater at the same level as surface water,
because of lack of awareness and knowledge of groundwater
issues and policy options.
People have clustered at the
water's edge throughout civilization for the most
fundamental of reasons: without water there is no life.
Every major city in the world has a body of water or aquifer
nearby, since rivers and lakes predetermined where people
would gather and dwell, groundwater constitutes about 98
percent of the fresh water on our planet (excepting that
captured in the polar ice caps). This makes it fundamentally
important to human life and to all economic activity.
Groundwater resources in and around the urban centers of the
developing world are exceptionally important as a source of
relatively low-cost and generally high-quality municipal and
domestic water supply. At the same time, the subsurface has
come to serve as the receptor for much urban and industrial
wastewater and for solid waste disposal. There are
increasingly widespread indications of degradation in the
quality and quantity of groundwater, serious or incipient,
caused by excessive exploitation and/or inadequate pollution
control. The scale and degree of degradation varies
significantly with the susceptibility of local aquifers to
exploitation-related deterioration and their vulnerability
to pollution. Management strategies need to recognize and to
address the complex linkages that exist between groundwater
Some 200 million people lived on Planet
Earth at the start of the modern era. That number rose to
2.5 billion by 1950. At mid-2008, the population is now 7.0
billion and is expected to reach 9.0 billion by 2040. It
thus took 1,950 years for the global population to grow
ten-fold but only an additional 58 years to nearly triple.
And throughout this period the global availability of water
resources has remained more or less constant. Growing ever
more food to feed rising populations will be possible only
with increasingly large amounts of water being used for
agricultural irrigation, even allowing for further advances
in plant genetics. Groundwater widely developed by private
initiative but often stimulated by 'soft loan'
finance, guaranteed crop prices, and rural energy subsidies
will be a very important source of irrigation water. At the
same time groundwater will continue to be the predominant
source of household water for the rural population in
Groundwater has an important role in forging the composition of surface water, supplying nutrients crucial for the development of balanced ecosystems and potentially introducing contaminants into otherwise pristine surface water. Due to water-rock interactions radium (Ra) in groundwater is typically much more abundant than in surface water. In saline environments Ra is soluble and is considered a conservative tracer (apart for radioactive decay) for Ra-rich groundwater seepage. Hence in coastal environments, where mostly fresh groundwater seep into saline surface water, Ra has been the prominent tracer for tracking and modeling groundwater seepage over more than three decades. However, due to its reactivity and non-conservative behavior, Ra is rarely used for tracing groundwater seepage into fresh or hypersaline surface water; in freshwater, Ra is lost mostly through adsorption onto sediments and suspended particles; in hypersaline environments Ra can be removed through co-precipitation, most notably with sulfate salts.
This work examines the use of Ra as a tracer for groundwater seepage into freshwater lakes and rivers and into hypersaline lakes. The study examines groundwater-surface water interactions in four different environments and salinity ranges that include (1) saline groundwater discharge into a fresh water lake (the Sea of Galilee...
Finding the best locations for artificial recharge of groundwater in a semi-arid area is one of the most challenges which water engineers concern about as these areas suffer from shortage in water supply and groundwater recharge. This study presents two ways to go about performing analysis; creating a suitability map to find out the suitability of every location on the map and another way is querying the created data sets to obtain a Boolean result of true or false map. The study area is Sadat City which is located in a semi arid area in the western desert fringes of The Nile delta in the north west of Egypt. Thematic layers for number of parameters were prepared from some maps and satellite images by the remote sensing techniques. These layers were classified, weighted and integrated in ArcGIS environment and by the means of the overlay weighted model a suitability map which is classified into number of priority zones was obtained. This map was compared with the true-false map of Boolean logic and the result was that the weighted model gives more flexible and more accurate suitability map. However Boolean logic is much easier and not time consuming, so it can be used as first estimations for the best locations and the final decision for the suggested location can be confirmed by more field reconnaissance.
To address water availability problems in a semi-arid country like South Africa, the National Water Act (RSA, 1998) proposes that specialists adopt an approach that is strategic, deliberate and dictated by socio-political reforms and socioeconomic development needs on a programmatic basis for long-term sustainability. To achieve this goal an approach is developed to determine community-groundwater compatibility as part of the initial stages of regional rural groundwater-development projects in the Eastern Cape Province, South Africa. The steps followed in the community-groundwater compatibility assessment include: A desktop study where available literature is collected and reviewed. From this information and history, the sociopolitical challenges that will have to be faced for the successful completion of the groundwater-development project in the study area can often be established. This is valuable information to assist the hydrogeological team in planning the community-groundwater compatibility assessment, taking note of pitfalls and lessons learnt from previous approaches that might not always have been successful. A socio-economic characterisation includes setting up a contact database for the community authorities and technical managers within the study. The contact database includes all contact details of the ward councillors/technical managers as well as any relevant information or comments made by the ward councillor/technical manager during the conversation. All identified stakeholders must also be contacted...
Groundwater is not being perceived as an important water resource and therefore has been given limited attention in South Africa. This is reflected in general statistics showing that only 13% of the nation's total water supply originates from groundwater. In contrast, most towns in arid areas depend on groundwater either as a sole supply or as an essential supply for drought management. The perception remains that groundwater is not a sustainable resource for bulk domestic supply and cannot be managed properly. Despite this, a growing number of municipalities utilise groundwater on a regular basis, and provide examples of successful management of this resource. Various guidelines for groundwater management in South Africa have been developed. These are valuable sources of information in terms of requirements and steps to protect and manage aquifers. However, an overarching groundwater management framework was still lacking. Hence, the Water Research Commission (WRC) has commissioned a project to develop a Groundwater Management Framework that incorporates all aspects of groundwater management at municipal level. The proposed Groundwater Management Framework aims to improve on the management of groundwater resources by equipping the responsible authorities with the required tools and capacity. This goes beyond data collection and monitoring...
Groundwater provides a range of services to people in Southern Africa; however, the benefits provided by these services are often not fully appreciated and factored into decisions about groundwater management and use. After outlining briefly the importance of groundwater in the region and the pressures facing groundwater, this paper discusses how economic valuation can help improve its management. The main focus of the paper is the presentation of the practical 5-step economic valuation methodology that has been developed as part of the Southern African Development Community (SADC) Groundwater and Drought Management Project. This methodology can be generally applied to groundwater management issues across the SADC region. The methodology is based upon an ecosystem services approach which considers all the potential services that groundwater provides, which can result in improvements in human welfare. These services include provisioning services such as water for domestic use, agriculture and industry; regulating services such as the recharge of surface waters and carbon storage benefits; and cultural services such as the tourism associated with wildlife at groundwater-fed watering holes. The methodology incorporates a 2-tiered valuation approach. The Tier 1 valuation is based on market pricing and value-transfer approaches and can provide an initial view of the economic value of a resource in a particular use. A value-transfer tool has been developed...