1. Over the past 30 years, farmers around the world have turned massively to pumped groundwater use, mainly through individual tube-wells : 113/300 M ha (Siebert et al, 2010). Groundwater use concerns newly irrigated areas, but also existing state and farmer-managed surface water irrigation systems. In these systems, groundwater use is often viewed as creating perturbations to their collective organization (e.g. Lightfoot, 1996). However, there is recent evidence of the integration of groundwater within existing surface water irrigation schemes (Ortega-Reig, 2014). Distributing groundwater from collective and individual tube- wells in a surface water irrigation system: the adaptability of the Sidi Okba oasis (Algeria) Meriem Farah HAMAMOUCHE 1, 2, Marcel KUPER 1, 2, Tarik HARTANI 3 1. IAV Hassan II. Madinate Al Irfane 10111 Rabat, Marocco. 2. CIRAD UMR G-eau. 73, rue JF Breton 34398 Montpellier cedex 5 France. 3. ENSA d’Alger, Rue Hassen Badi Belfort El Harrach, Alger, 16000, Algeria. Introduction Whereas individual tube-wells are limited to a relatively small number of farmers, who tend to be large landowners and wealthy practicing high value crops, the active groundwater markets of Sidi Okba enable the access to groundwater to the vast majority of farmers, including those irrigating small and scattered plots of palm trees of traditional varieties with low commercial value. The results of this study show the adaptive capacity of the Sidi Okba irrigation system, which was able to overcome severe surface water shortage by distributing groundwater to its surface water users. Through collective action, by integrating new water resources and adapting the infrastructure, and evolving rules the irrigation community thus made groundwater the new engine of the Sidi Okba oasis. Results Methods Discussion and conclusions Objectives The objective of this study is to analyze how groundwater was integrated in a farmer-managed surface irrigation scheme in South-East Algeria, focusing on the adaptations of the irrigation infrastructure and the distribution rules. The study took place in the Sidi Okba oasis (Algeria), where groundwater became over the past 30 years the main water resource following a severe hydraulic crisis in the 1970s and 1980s. Groundwater is accessed through a host of individual and collective tube-wells owned by different actors. Study area: References You should check your references thoroughly. We only accept references written using the latin alphabet. The following section shows a sample reference list with entries for journal articles [1], a chapter [2], a book [3], as well as an institutional URL [4]. Methods: This study is based on an : -inventory of all tube-wells in the oasis; -mapping of the irrigation infrastructure; -analysis of the functioning of the water distribution through observations and interviews. 1. Distribution of groundwater Groundwater is distributed in the oasis using the surface water infrastructure through water markets. Groundwater markets supply 70% (738/1064 ha) of the irrigated area of the oasis with 16 tube-wells, whereas the remainder of the area 30% (325/1064 ha) is catered to by 26 individual tube-wells (see figure 2). Farmers having an individual tube-well are generally located in the tail-end of the irrigation command, as it is difficult to convey tube-well water to them due to seepage losses. In addition, these large-scale farmers are situated on the outside of the oasis, and grow high value date palm varieties on large plots for which they prefer to have an individual tube-well (See figures 1, 2). Figure 2: Distributing groundwater from collective and individual tube-wells in a surface water irrigation system. Tube-wells Agricultural water management cooperative Tube-wells associations Tube-wells private water sellers 1 seguia 7 seguias 5 seguias 1 seguia Figure N°3 : Organization of groundwater markets. Area covered by water providers / groundwater markets area (%) Agricultural water management cooperative 65 Tube-wells associations 69 Private water sellers 52 Table 1: Operating rang of groundwater markets. Distribution rules have been progressively adopted for groundwater. Water users can buy the combined volume from the different water providers, or take only the water from one of the sellers. The water delivery to secondary canals follows a predefined system of water turns, whereby each secondary canal receives water for a period of 20-45 days. Study area coexistence particularity : Dam « Leakage » Dam releases Groundwater: State tube-wells Collective tube-wells Individual tube-wells multitude of water providers multitude of water resources surface canals 3. Groundwater markets : typology of water providers There are three types of water providers, whose tube- wells are spread over the 14 secondary canals (seguia benat) : 1)The agricultural cooperative in charge of surface water management also provides groundwater through 4 large tube-wells with an average discharge of 66 m³/h. 2)Three informal tube-well associations (20-62 shareholders) with tube-wells having an average discharge of 55 m³/h. 3)Nine private water sellers having tube-wells with an average discharge of 34 m³/h. 4. Using and adapting the surface water infrastructure and the distribution rules Groundwater is distributed through water markets using the existing surface canals that have been adapted to cater to this additional resource, in particular by providing multiple connections between secondary canals (seguia bnat), and thus increasing the operating range of tube-wells (see figure N°2) 86% (635/738 ha) of groundwater markets area is covered by interaction of several tube-wells of three water providers, thus avoiding a water monopoly (see table N°1). Farmers relying on water markets do so because : -their plots are scattered, and a single individual tube- well cannot cater to these different plots. -the investment of a tube-well (15-20,000€) is too high for certain farmers, especially when growing traditional palm tree varieties of low market value (See figures 1 and 2). 2. Individual or collective access to groundwater Individual tube-wells Physical environmental -Arid climate -Severe and successive drought -Large aquifer reserves Surface water : Dam -Siltation in dam (80%) -Insufficient water resources Access and use groundwater (tube-wells) Groundwater markets Surface irrigation network Farm characteristics Large landowners -Large scale farm -Mixed cropping : commercial palm dates (Deglet nour), greenhouse horticulture... -Crop high market value Small and medium landowners -Scattered plots -Monocropping : local palm dates traditional varieties -Crop low market value Figure 1: Factors encouraging the individual or collective access to groundwater. Lightfoot, D.R. (1996) : Moroccan khettara: Traditional irrigation and progressive desiccation, Geoforum, 27: 261-273. Ortega-Reig, M et al (2014): The integrated use of surface, ground and recycled waste water in adapting to drought in the traditional irrigation system of Valencia, Agricultural Water Management, 133: 55-64. Siebert, S et al. (2010): Groundwater use for irrigation - a global inventory, Hydrology and Earth System Sciences, 7:3977-4021.