La presente investigación evalúa el grado en que el dique-embalse Paso de las
Piedras ha interrumpido la continuidad hidrológica del río Sauce Grande y cuantifica los
impactos de la regulación hidrológica sobre el régimen de caudal, la morfología y la
temperatura del agua del río aguas abajo del embalse. El trabajo de tesis presenta una
evaluación integral y sistémica de los impactos del dique-embalse basada en el
entendimiento de los procesos fluviales que ocurren aguas arriba del mismo. Además de
proveer información sobre los impactos hidrológicos, morfológicos y térmicos de la
construcción y operación del dique-embalse, este estudio genera nuevas series de datos
climáticos e hidrológicos que proporcionan una importante plataforma sobre la cual
basar futuras investigaciones de la cuenca del Sauce Grande. Por otra parte, este estudio
implementa un marco metodológico aplicado al análisis hidro-geomorfológico de
cuencas no aforadas que tiene un gran potencial de aplicación en otras cuencas de la
región y en otras regiones semiáridas del mundo. / Despite the regional importance of the Sauce Grande River as main source for water supply
and the large capacity of the Paso de las Piedras Reservoir, both the hydrology of the river
basin and the effects of the impoundment on the river environment remain poorly
evaluated. This study provides the very first assessment of the degree of flow regulation
induced by the Paso de las Piedras Dam on the middle section of the Sauce Grande River,
and quantifies its impacts on the hydrology, morphology and patterns of water temperature
of the river downstream from the impoundment. In addition to providing new information
on the response of regulated rivers to upstream impoundment and on the effects of
impoundment on the Sauce Grande River specifically, this study generates spatial, climatic
and hydrologic data and implements a methodological framework to hydrological
assessment of ungauged basins.
The methods include a set of procedures performed to generate data and a set of procedures
performed to hydrological and morphological assessment. Methods used to generate data
include (i) terrain modelling of the river basin, (ii) filling and modelling of climatic data,
(iii) hydrological modelling of the upper river basin, and (iv) flow simulation and
calculation. Methods used for hydrological and morphological assessment include (i)
inspection of the water balance of the dam reservoir and quantification of the reservoir
size-yield-performance relationships, (ii) quantification of the degree of hydrological
alteration of the river downstream, (iii) classification of diurnal regimes of water
temperature and quantification of their climatic sensitivity, and (iv) GIS-based diachronic
analysis of change in the fluvial forms and the fluvial landscape.
Results revealed that reservoir inflows are driven by varying climate conditions, whereas
reservoir outflows are constrained by the dam purpose for water supply. Large volumes of
water are yielded annually (73 % of the mean annual runoff) and the remaining volume is
conserved within the reservoir for periods of drought. These patterns of flow regulation
have seriously affected the hydrology and water quality of the river downstream. Floods
were fully eliminated and the magnitude and frequency of high and low flows were
reduced dramatically, with substantial increase in the duration of similar flow conditions.
Furthermore, summer temperatures were depressed, winter temperatures were increased,
and diurnal fluctuations were altered in both magnitude and timing. Analysis of the
geomorphic response to altered hydrology revealed fluvial stability. Lateral and vertical
channel activity was related to human intervention to facilitate the evacuation of dam
outlets and spills more than to natural adjustments to reduced flow discharge and sediment
load. The reduced flow, even if sediment-free, is incompetent to work its channel and at
present, the downstream channel morphology is a relic of a fluvial environment created in
the past under conditions of higher energy.
The new climatic, hydrologic and morphologic information yielded herein has triple
applicability: (i) it informs dam managers about the complex behaviour of the river system,
(ii) it contributes to improve reservoir operation procedures while maintaining the overall
integrity of the river system, and (iii) it provides a consistent scientific platform on which
to base further research efforts conducting to an interdisciplinary framework of river
restoration. Furthermore, the methods implemented in this research are widely transferable
to hydrological assessment of ungauged basins worldwide, with special applicability to
semiarid regions.
| Identifer | oai:union.ndltd.org:uns.edu.ar/oai:repositorio.bc.uns.edu.ar:123456789/473 |
| Date | 18 June 2013 |
| Creators | Casado, Ana |
| Contributors | Campo, Alicia María, Peiry, Jean-Luc |
| Publisher | Universidad Nacional del Sur |
| Source Sets | Universidad Nacional del Sur |
| Language | Spanish |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation, Text |
| Rights | 0 |
Page generated in 0.0025 seconds