Escenario de demanda hídrica agrícola para la optimización del riego de los pequeños productores de la zona plana de la cuenca del río Guabas.

The Association of Users of the Guabas River basin (ASOGUABAS), in agreement with the research group on integral management of irrigation for agricultural development and food security (WATER) from Univer- Sara Marcela Paz1 Valen tina Munoz Agudelo2 Andres Fernan do Echeverri S3 Norberto Urrutia Cobo4 Recibido: 01-10-2012 Aceptado: 14-11-2012 6 sidad del Valle, conducted a study to determine the water demand of small producers from the flat area of the drainage basin of the Guabas River, as a first step toward efficient use of water. Climatic and cartographic information was collected of the flat area of the municipalities of Guacari and Ginebra, department of Valle del Cauca. Subsequently, the agricultural zone of each property was determined by using geo-global positioning technology. The water needs of crops, contribution of rainfall, needs of irrigation, and water demand on a monthly level were calculated. Results indicate that, according to the behavior of the evapo-transpiration and precipitation in the study area, two times of irrigation needs exist associated to rain periods (bimodal behavior). In addition, it was identified that the current demand is high due to the poor state of infrastructure in existing water distribution channels; hence, despite having irrigation methods located on the farms, a critical module of irrigation of 0.85 ls-1 is present. On the basis of the above, a simulation of a scenario of demand improving the efficiencies of the transmission and distribution system of irrigation water was performed and a critical module of 0.4 ls-1 was achieved.