Statistical Terms Glossary

Portion of total precipitation from a given area that appears in natural or artificial surface streams.; A portion of rainfall, melted snow or irrigation water that flows across the ground's surface and is eventually returned to streams.; Rainfall or snowmelt that fails to infiltrate into the soil and which flows over the soil surface.

The most common definition applied by international organizations to separate rural and urban regions is that developed by the Organisation for Economic Co-Operation and Development (OECD). The definition distinguishes two hierarchical levels of territorial unit: local and regional. At local community level the OECD defines rural areas as communities with a population density below 150 inhabitants per square kilometre. At regional level, the OECD distinguishes larger functional or administrative units by their degree of rurality, depending on what share of the region's population lives in rural communities.

A set of activities, involving securing water, food, fodder, medicine, shelter, clothing and the capacity to acquire above necessities working either individually or as a group by using endowments (both human and material) for meeting the requirements of the self and his/her household on a sustainable basis with dignity.

De facto population living in areas classified as rural (that is, the difference between the total population of a country and its urban population). Data refer to 1 July of the year indicated and are presented in thousands.

Percentage of the rural population using improved water sources. An “improved” source is one that is likely to provide safe"" water, such as household connection, a borehole, etc. Current information does not allow yet establishing a relationship between access to safe water and access to improved sources, but WHO and UNICEF are examining this relationship.

A geologic feature, in North Africa, which is a smooth, flat, plain usually high in salt; after a rain the plain may become a marsh or a shallow lake until the water evaporates. Also known as sebkha, sebcha, sebka, sibjet.

The concept of a safe biological limit has been developed and is being used increasingly in stock assessments to indicate the status of stocks. Stocks are considered to be within safe biological limits if the spawning stock biomass is above a precautionary value which is higher than the level at which recruitment is impaired and fishing mortality is below a precautionary value which is lower than that which would give rise to a high probability of recruitment failure. Poor recruitment or a high level of fishing mortality do not in themselves, therefore, give an indication of the real status of a stock.; Stock is considered to be outside safe biological limits (SBL) when the spawning stock biomass (SSB) (the mature part of a stock) is below a biomass precautionary approach reference point (Bpa), or when the fishing mortality (F) (an expression of the proportion of a stock that is removed by fishing activities in a year) exceeds a fishing mortality precautionary approach reference point (Fpa). However, a stock can be considered within safe biological limits even when the spawning stock biomass is lower than the biomass precautionary approach reference point (Bpa) but the Fishing mortality is lower than the fishing mortality precautionary approach reference point (Fpa) (SSB<Bpa but Fpa<F).; 3. A Limit reference point, usually the stock biomassbelow which recruitment will decline substantially.