Policies and practices of water management under water scarcity must focus on specific objectives according to the causes of water scarcity. An integrated technical and scientific approach is essential to develop and implement the management practices appropriate to deal with water scarcity. Policies and practices must be based on the assumption that water will not become abundant, so that water management policies and practices have to be specific for water scarcity, i.e. for man to cope with the inherent difficulties.
To cope with water scarcity means to live in harmony with the environmental conditions specific to and dictated by limited available water resources. For millennia, civilisations developed in water scarce environments and the cultural skills that made it possible to live under such conditions are an essential heritage of those nations and peoples.
Progress in XX century often questioned traditional know-how, which has in some situations been replaced by modern technologies and management rules directly imported from other areas having different physical and social environments. Water consumption and demand has increased everywhere for domestic and urban uses, for agriculture and irrigation, for industry and energy production, and for recreation and leisure. However, these increases became particularly evident in regions where water is scarce or, at least, not abundant. Therefore, man made dry regimes are now adding to the natural water scarce conditions, in many cases aggravating the existing situation.
Solving water management problems that are faced in water scarce regions calls for innovative approaches to cope with water scarcity. Innovation includes the adaptation of traditional know-how to the current day challenges, the adaptation of the externally available technologies to the prevailing physical and social conditions, and the creation of new and well adapted technologies and management approaches. Innovation must be used to assist man to cope with the environmental constraints and engineering and managerial solutions must be found that are specific to the existing causes for water scarcity: nature produced aridity and drought, and man induced desertification and water shortage.
Aridity:
Among other characteristics, aridity is very often associated with:
population growth that is above the capacity of support of the available natural resources, water in particular,
high pressure on natural resources, producing their progressive degradation,
strong competition for water for human, economic, and social uses, more recently including those of a recreational and leisure nature,
water is the limiting resource for development, particularly for agriculture and food,
vulnerable and fragile natural ecosystems,
the soil resource is often degraded by erosion and salinity hazards, which are aggravated by poor agricultural water management,
poverty and low educational levels of the populations threaten development.
Therefore, the sustainable use of water resources under aridity, implies:
the effective adoption and implementation of integrated land and water resources planning,
the improvement of water distribution and irrigation systems to achieve an increased service performance, which would induce efficient water use and production,
the adoption of water allocation policies favouring reduced demand, conservation and efficient use,
valuing the water as an economic, social and environmental good, including for nature conservation,
measures for augmenting the available water resource, including waste water and drainage water re-use, conjunctive use of water from different origins, and the use of low quality and saline water,
the adoption of appropriate water and irrigation technologies that favour water productivity and contribute to avoidance of water wastes and losses,
innovative institutional and legal measures, including the transfer of responsibilities to users’ associations,
the users participation in water resources planning and systems management,
education and training of water managers, operators and users,
increased public awareness of water, soil and ecological conservation.
Drought:
Water management under drought requires measures and policies which are common with aridity, such as those to avoid water wastes, to reduce demand and to make water use more efficient. However other possible measures are peculiar to drought conditions and may be beyond the scope of the more common water management issues and policies. The peculiar characteristics of droughts may require use of specific measures. The complexity and hazardousness of droughts make their management particularly difficult and challenging.
Drought phenomena, including their causes, impacts, and other characteristics are often not well understood. The perception of a drought is different according to the activities affected and the disciplines professions and groups impacted by the drought.
Forecasting of when a drought is likely to begin or to come to an end is extremely difficult.
However, important progress is being made in relation to the possibilities of using the El Niño Southern Oscillation (ENSO) and, to a lesser degree, the North Atlantic Oscillation (NAO) as forecasting tools. Examples are given e.g. in Vogt and Somma (2000). Case studies relative to USA and Australia are analysed by Le Comte (2000) and Power (2000).
Droughts have a slow initiation and they are usually only recognised when the drought is already established. They are of long duration, and usually affect large areas.
Their impacts are pervasive. Implementing drought control or drought preparedness measures and policies are receiving limited political attention in a changing economic and social environment, where growing pressures on natural resources, and development of man-induced water stressed conditions are creating new priorities. Nevertheless, drought aggravates these problems and diminishes the carrying capacity of the ecosystems.
The vulnerability of agricultural activities to drought have not decreased but have increased both in developed and less developed countries. In less developed countries food shortages have become much more frequent.
A better understanding of droughts is essential to develop tools for prediction or forecasting of drought initiation and ending, so that these occurrences may be clearly recognised. This is essential for timely and appropriate implementation of measures to cope with a drought. Planning for droughts tends not to receive priority attention of decision and policy makers because drought has diverse impacts. The slow initiation and undefined end of a drought makes it difficult to select the opportunity to take defensive or remedial action.
When a flood occurs every symptom is obvious and opportune measures can be taken, usually with the support of public opinion since the disaster is easily recognised by all. In the case of a drought the disaster elements only become evident much later, when the drought has already started. Then the impacts last for a long time after the drought has ended, particularly if the lack of preparedness helped to turn the disaster into a catastrophe.
Avoiding such problems requires appropriate monitoring, and for effective drought watch systems be implemented. Drought warning then becomes possible (Wilhite et al., 2000;
Rossi, 2002).
Difficulties on predicting droughts are well known. Nevertheless, an adequate lead-time - the period between the release of the prediction and the actual onset of the predicted hazard - is more important than the accuracy of the prediction (Easterling, 1989). It is the lead-time that makes it possible for decision and policy makers to implement policies and measures to mitigate the effects of drought. In the case of agriculture several months lead-time is essential to make it possible for farmers to take decisions to alter crop and agricultural systems to cope with drought.
Difficulties in prediction have lead some to develop early warning indices (Wilhite et al., 1987, 2000). These indices can be of a meteorological or hydrological nature, combining actual and time series data, with different degrees of sophistication in statistical treatment; or they may result from stochastic treatment of reservoir volumes (Rossi, 2002).
Real-time agroclimatological networks can support early warning. Early warning does not provide as long a lead-time as prediction. Nevertheless it definitely helps with the timeliness of decisions.
Researchers face, therefore, a challenge for developing prediction and early warning skills appropriate to the climatic and agricultural conditions prevailing in different drought prone areas. Institutional arrangements are also needed to provide the links between data collection, data treatment, the research, and the potential users and decision-makers, as analysed hereafter.
These problems, among others, represent very difficult challenges for the development of methods to cope with droughts and to mitigate their impacts. These challenges correspond to the multiple facets of the drought phenomena.
because they are unpredictable or difficult to predict, preparedness measures are paramount in any attempts to cope with droughts;
as droughts have pervasive long term effects and their severity may be very high, appropriate reactive measures are required;
the break in the natural water supply usually requires changes in water allocation and delivery policies, as well as in the day-to-day management of water supply and irrigation systems;
water supplies may be supplemented using non conventional sources, including waste
and low quality waters, thus requiring the enforcement of appropriate policies to control the respective impacts;
diminished water supply during droughts requires that farmers and other users be capable of adopting reduced demand and efficient water use practices;
incomes of farmers and other water users may be drastically reduced, so financial support measures are also required to complement reactive measures;
among preparedness and reactive measures, water pricing and penalty policies may contribute to the effectiveness of drought management measures, and
the awareness of populations of drought water scarcity must be developed to create a world-wide behaviour pattern oriented to reduce water wastage, encourage water savings and favour water conservation practices.
Desertification and water shortage:
Desertification and water shortage are man induced and are associated to problems such as soil erosion, land degradation, mainly through salinisation, over exploitation of soil and water resources, and water quality degradation. As a result there is a need for policies and measures to be oriented to solve the existing problems and to prevent new occurrences of these problems. Therefore, combating desertification and water shortage includes:
re-establishing the environmental balance in the use of natural resources.
enforcement of integrated land and water planning and management policies,
restoring the soil quality, including the adoption of soil and water conservation measures,
defining new policies for water allocation, favouring reduced demand and water conservation practices,
controlling ground-water abstractions and developing measures for recharging the aquifers,
minimising water wastage,
combating soil and water salinisation,
controlling water withdrawals,
adopting policies and practices for water quality management,
implementing policies of economic incentives to users, including graduated water pricing and penalties for misuse and abuse of natural resources.