An in-depth qualitative and quantitative research with an integrated approach to watershed management carried out in Yacyreta Lake in Paraguay is reported. This case study research is based in the Watersheds of the Mboi Cae and Quiteria
Rivers, and involves a) assessing the current state of knowledge of the
watersheds; b) an analysis to determine socio-environmental conflicts and to
propose solutions and strategies from the perspective of the local watershed
council c) the determination of achieved integrated watershed management of the watersheds and d) the assessment of spatial aquifer intrinsic vulnerability to
pollution. The research is supported by participative social research techniques,
workshops, and semi-structured interviews; also, a multi-criteria standard was used to assess integrated watershed management, together with GIS - based models (DRASTIC and GOD) to determine aquifer vulnerability to pollution.
Sources of information and literature review for the study area were organized in a summarized table, identifying available data and previous works carried at the
watershed level. Socio-environmental conflicts were identified related to
deforestation of riparian forests; also, pollution of soil and water and soil
degradation by malpractices in agriculture; health related problems, environmental degradation and problems derived from solid wastes and their insufficient treatment and deposition. The local watershed council was capable of analysing these prioritized conflicts and proposed strategies according to its legal competence. Assessing IWM showed an advancement of 35 % of the total
obtainable qualification and a set of critical elements were identified to advance
towards IWM. Assessing groundwater vulnerability to pollution resulted in
intermediate-high levels of vulnerability (DRASTIC: 56% of the watersheds with
values of 140-159; GOD: 95% of the watersheds with values of 0.4 - 0.5), with
maximum vulnerability in the lower parts of the watersheds in urban areas and
where the flooding of the Yacyreta lake will take place, making it more necessary
to consider the threat of urban pollution to the Basalt Aquifer of the Guarani Aquifer System. Several parts of the research were integrated discussing consistency and discrepancy in results.
Keywords: Watershed management certification, socio-environmental conflicts,
GIS, DRASTIC, GOD, groundwater vulnerability to pollution, Yacyreta,
Encarnacion, ltapua, Mboi Cae River, Quiteria River.