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Centro Agronómico Tropical de Investigación y Enseñanza (CATIE) 2017

Análisis del índice de vulnerabilidad a sequía e identificación de sitios para cosecha de agua en la subcuenca media del Río Viejo, Nicaragua

Silva Paredes, Oscar D.

Titre : Análisis del índice de vulnerabilidad a sequía e identificación de sitios para cosecha de agua en la subcuenca media del Río Viejo, Nicaragua

Auteur : Silva Paredes, Oscar D.

Université de soutenance : Centro Agronómico Tropical de Investigación y Enseñanza (CATIE)

Grade : MAGISTER SCIENTIAE en Manejo y Gestión Integral de Cuencas Hidrográficas 2017

Résumé
This study was carried out in the middle sub-basin of the Río Viejo, municipality “La Trinidad”, department of Estelí, Nicaragua. The sub-basin is part of the territory of Nicaragua that is constantly affected by the phenomenon of drought and in many of its micro-basins there are problems of availability of water. The objectives of the study were to analyze the vulnerability index to drought, to identify and characterize sites for water harvesting, and to propose suitable works to capture and store the runoff to meet the water needs of family farming. In the process, available meteorological data from 6 INETER stations, heatwave, groundwater, MED, coverage, land use, soil type, land use conflict maps and population density were used. Household surveys were conducted to obtain information on socioeconomic indicators such as education, institutional coverage, community organization, economic capacity, economic dependence, unemployment, use of economic instruments, land tenure, drinking water service, implementation of technologies and training. The most vulnerable communities in the middle basin of the Río Viejo were identified by performing an analysis of biophysical and socioeconomic variables and indicators that define the vulnerability index to drought. Once the vulnerability index was defined by biophysical and socioeconomic factors, the average was obtained to achieve the overall vulnerability index of each community. At the general level, the communities in the middle basin of the Río Viejo have a high vulnerability index, except in the communities of “Los Carbonales, Las Limas, Sabana Larga-Ocotillo, Potrerillo, La Laguna and Rosario Arriba”, which show an average vulnerability index to the climatic conditions of drought. There has also been an identification and characterization of sites for water harvesting, where through a participatory workshop with producers of micro-watersheds, a first approximation was made to define possible sites, that were characterized, the process was complemented by travel and field survey with company of producers and in addition, with the evaluation of geographic information system data available in the zone. On the other hand, an evaluation of existing water potential for the water harvest was carried out, determining the water demand of the crops and the livestock requirements in the farms where the identified sites are located and compared to the availability of water by runoff of the drainage areas of these sites, which was estimated using the HEC-HMS model, making use of the daily precipitation data of the San Lorenzo II station. It is proposed a work to harvest water in each site to supply the entire agricultural deficit of the farms and a second proposal adjusted to the availability of space of the identified sites, the design proposal of these works was based on the HEC-HMS model. The study included a sensitivity analysis of the HEC-HMS model, in order to evaluate the parameters used. It was possible to identify 11 sites, which present drainage areas with good potential to supply agricultural water needs. The use of the HEC-HMS allowed performing conceptual design proposals of the water harvesting works with a sensitive NC parameter in its variation for the estimation of the runoff, but like the other parameters, enabled to obtain a model with good results.

Mots clés : Río Viejo, vulnerability index to drought, water availability, biophysical indicators, socioeconomic indicators, water harvesting, site identification

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Page publiée le 30 mars 2019