Water exploitation
Water exploitation is referred to the extraction of water for irrigation and human consumption. Water exploitation is greatly connected with agriculture especially in the Mediterranean coastal region where intensive irrigated agriculture is widespread. Nevertheless, in many areas a large contribution to water exploitation is connected with the industrial and residential sectors and, seasonally, with tourism. Water exploitation can be estimated by "the exploitation index" that is defined as withdrawal of conventional freshwater resources (surface and groundwater) over total renewable resources (expressed in %).
| Aim of the method/technique |
The proposed index of water exploitation aims to assess the degree of water exploitation or to which degree the amount of water used is sustainable or over-exploited in relation to the water that is available in an area. |
| Scale – spatial and temporal |
The scale for water exploitation index assessment is the watershed. Water exploitation index usually presents a high spatial variability and temporal change.
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| Brief description |
Exploitation of water resources can be quantitatively analyzed by comparing the amount of water recharge of aquifers or the amount of water stored in water reservoirs with the amount of water actually used. It can be estimated by assessing: (a) the water consumption by various sectors, (b) the decrease in river and spring flow, and (c) the appraisal of the recharge rate in a certain hydrological area. The following classes of exploitation can be distinguished: (a) water overexploitation if exploitation>recharge, (b) sustainable water exploitation if recharge rate>exploitation rate >0.8 recharge rate, and (c) without problems of overexploitation if recharge rate>>exploitation rate. |
| Data requirements |
The data required are: (a) water consumption per sector (agriculture, industry, urban, tourism), (b) amount of water recharging aquifers plus surface water storage, (c) amount of water available in rivers and springs. Such data are obtained for a hydrological year and for a period of at least 20 years.
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| Main applications in cropland and forests and shrubland regions |
The water exploitation index is an important parameter for assessing the vulnerability of an area to soil salinization and water stress to the growing plants. Overexploitation of water resources leads to brackish water intrusion in the aquifers, low resilience of an ecosystem under adverse climatic conditions, higher land vulnerability to desertification, conflicts among societies, threat to biodiversity of forest water bodies etc. |
| Strengths and weaknesses |
Hydrological data for an area usually are not easily available mainly because of the great number of organizations involved in water resources management. Furthermore, long term series of hydrological data for a specific watershed are usually limited. |
