P |
| Palaearctic | One of the eight ecozones into which the world is divided. This ecozone includes the terrestrial ecoregions of Europe, Asia north of the Himalaya foothills, northern Africa, and the northern and central parts of the Arabian Peninsula. |
| Panchromatic imagery | Imagery taken of all wavelengths within the visible spectrum (though not uniformly). |
| Paramecium | A single-celled, microscopic aquatic organism with hairlike appendages (cilia) around its body used to move around and capture bacteria. |
| Participation | A process that enables a wide range of stakeholders from the public and private spheres to participate in and influence decision-making processes, especially at the local level. |
| Participatory planning | A planning approach in which all stakeholders, and in particular the envisaged beneficiaries are part of the decision process. |
| Pastoralism | A livelihood in which people living in the semi-arid areas support themselves by tending domesticated animals that feed on grass and other available plant foods and water sources, usually in areas characterized as semi-arid to semi-desert. |
| Pathogen | Microscopic parasite organism that causes disease in a host. Disease causes the host to be less fit and may eventually cause premature death. |
| Per capita | Usually used in the field of statistics to indicate the average per person for any given concern, such as income, crime rate, etc. |
| Percolation | Flow of a liquid through an unsaturated porous medium, e.g. of water in soil, under the action of gravity. |
| Perennial | A plant in which the vegetative structures live year after year (some definitions say at least 3 years). |
| Perennial river | A river that flows in at least parts all year round. |
| Periphyton | The layer of algae, microorganisms and organic material coating the surface of stones, plants, and hard objects on the beds of streams, rivers, and reservoirs. See also biofilm. |
| Persistent Organic Pollutants (POPs) | Organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes. |
| Pesticide | Chemical agent used to kill insects, usually associated with agriculture, but also associated with insect pest control in tourist areas, such as game parks. |
| pH | Scale used to measure the alkalinity or acidity of a substance through the determination of the concentration of hydrogen ions in solution. A pH of 7.0 is neutral. Values below 7.0, to a minimum of 0.0, indicate increasing acidity. Values above 7.0, to a maximum of 14.0, indicate increasing alkalinity. |
| Photosynthesis | The process by which plants use energy from the sun to transform carbon dioxide (CO2) and water into carbohydrates and other compounds. |
| Physical water scarcity | A physical lack of water available. |
| Physiochemical | A term used to denote something influenced by physical and chemical characteristics. |
| Physiographic | Adjective from physiography (or, Physical geography) – one of the three major subfields of geography. Physical geography focuses on understanding the processes and patterns in the natural environment, as opposed to the cultural or built environment, the domain of human geography. |
| Phytoplankton | Microscopic plants suspended in the open water. |
| Pioneer species | Plant species that dominate a community in the early stages of ecological succession. |
| Pixel | Picture element is the ground area corresponding to a single element of a digital image data set. A two-dimensional ensemble of pixels forms the geometric grid on which an image is built. |
| Policy | A plan or course of action intended to influence and determine decisions, actions, and other matters. |
| Policy coordination | A voluntary and largely unenforceable alignments of national policies and measures in particular fields. |
| Policy harmonization | An agreement on the manner in which each Member State will exercise or use a particular instrument over which it retains control. |
| Political insecurity (in terms of water transfers) | The insecurity of a country when a water-scarce country depends on a water-abundant country for critical water supply and when the water-abundant country depends on the water-scarce country for its export revenue. |
| Pollutant | Generally, any substance introduced into the environment that adversely affects the usefulness of a resource or the health of humans, animals, or ecosystems. |
| POPs (Persistent Organic Pollutants) | Organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes. |
| Population | In biology, a population is the collection of inter-breeding organisms of a particular species; in sociology, a collection of human beings. |
| Porosity | Ratio of the volume of the interstices in a given sample of a porous medium, e.g. soil, to the gross volume of the porous medium, inclusive of voids. |
| Potable | Water of a quality that is fit for consumption by humans or animals. |
| Potential evaporation | The amount of evaporation that would occur if there was sufficient water available. |
| Poverty | The situation facing those in society whose material needs are least satisfied. Inability to afford an adequate standard of consumption because of low income is referred to as income poverty. If, apart from low income, a country is characterised by malnutrition, poor health, low survival rates, low literacy levels, inadequate housing and living conditions, etc., then there is human poverty. |
| Poverty alleviation | Reduction of poverty through public policies. |
| Poverty line | A measure of the money income required to attain a basic minimal standard of living – enough to purchase a nutritionally adequate food supply and to provide for other essential requirements. |
| Poverty Reduction Strategy Papers (PRSPs) | Prepared by governments in developing countries to present the macroeconomic, structural and social policies and programs that a country will pursue to promote broad-based growth and reduce poverty. PRSPs contain objectives and criteria to monitor progress towards meeting these objectives. |
| Precipitation | (1) Liquid or solid products of the condensation of water vapour falling from clouds or deposited from air on the ground.(2) Amount of precipitation (as defined under (1) ) on a unit of horizontal surface per unit time. |
| Predator | An animal that kills and eats other animals. |
| Prevalence of HIV | The AIDS / HIV prevalence rate in selected populations refers to the percentage of people tested in each group who were found to be infected with HIV. |
| Primary aquifers | Aquifers with intergranular porosities and permeabilities occur which produce the water-bearing characteristics. |
| Primary consumer | An animal that eats autotrophs. |
| Primary producer | Produces the first form of organic carbon from inorganic compounds. See also autotroph. |
| Primary production | The production of organic matter, such as new cells, mainly by photosynthetic plants. |
| Private resources | Resources for which consumption is subtractive and to which access can be controlled (access is exclusive). |
| Privatisation | The sale of public assets to individuals or private business interests. |
| Producer | See autotroph. |
| Protected area | An area in which resource use and access is managed to protect valued environmental and natural resources. |
| Protists | A collective term for eukaryotes that are not considered true animals, plants, or fungi; or, members of the kingdom Protista. |
| Protocol | An instrument of implementation of the SADC Treaty, having the same legal force as the Treaty. |
| Protocol on Shared Watercourses | The protocol on Shared Watercourses in the Southern African Development Community (SADS) Region, was concluded as a legally binding document, in order to ensure equitable sharing of water and efficient conservation of the scarce resource. It established the River Basin Management Institutions and its financial and regulatory framework. |
| Protozoa | A large group of single-celled eukaryotic and often microscopic organisms. |
| PRSPs (Poverty Reduction Strategy Papers) | Prepared by governments in developing countries to present the macroeconomic, structural and social policies and programs that a country will pursue to promote broad-based growth and reduce poverty. PRSPs contain objectives and criteria to monitor progress towards meeting these objectives. |
| Public good | A resource with non-subtractive consumption and unlimited access. Protection from UV radiation by the ozone layer is an example of a public good. |
| Pula | The currency of Botswana. Pula literally means rain in Setswana language, because rain is very scarce in Botswana and therefore valuable. Pula also means blessing as rain is considered a blessing. |
| Purification plant | A facility that treats raw water and removes its impurities, making the water safe. |
