Tese
Uso dos dados da missão GRACE para estudo dos eventos de estiagem na bacia hidrográfica do Rio Uruguai, no período entre 2003 a 2015
Fecha
2019-09-30Autor
Moraes, Indiara Bruna Costa Moura
Institución
Resumen
Cities located in the Uruguay River Basin have been hit periodically by droughts that have
caused major economic damage to the region. There is a wide range of flow rates, since the
occurrence of major droughts, affecting human and animal supplies, experiencing losses in
Primary Sector output and indirect effects on other sectors, and also, the increase in the cost of
living of the population. The objective of this research is to analyze variations in total water
storage by the GRACE Mission (Gravity Recovery & Climate Experiment) in the Uruguay
Basin Hydrographic Region, allowing a better understanding of drought and behavior along
rivers, mainly in the low coverage areas of the river stations between 2003 and 2015. In this
research, masks of CSR GRACE RL05 solutions were used to obtain the Equivalent water
thickness in cm. The time series of the GRACE mission were compared with the wells, where
the weighted average was applied, considering all wells in the region, based on the area of
influence of each well determined by the Thiessen polygons. A priori, fluviometric stations
were selected in the same municipalities that monitor groundwater wells. Monthly averages
were calculated on the water quota information obtained from the readings of the rulers and
compared the behavior of water levels with EqW and the levels of underground wells. The
records of droughts obtained from decrees of emergency situation and state of public calamity
were divided into numbers of municipalities affected per year and number of events per year,
as there are municipalities with more than one event per year. And the normalized vegetation
index obtained from the MODIS sensor during the study period was used to correlate with the
EqW obtained by the mascon solutions of the GRACE mission. To verify the correlation
between the EqWs and the normalized vegetation indices, a geographically weighted regression
was performed, between the EqW values and the normalized vegetation indices, obtaining the
value of R² = 0.979. The methodology used was presented as an option for the evaluation of
drought events in the Uruguay River Basin. There was a direct relationship between the increase
in emergency decrees or state of emergency with the decrease in EqW levels in the
aforementioned area, allowing note that EqW level of decline begins months before the decrees,
realizing that the drought is the path from 1 year to 6 months before and plan economically for
such an event because the basin takes about four months to recover from the great peak of the
drought. As the time series of the GRACE mission is still small for hydrological studies, suggest
a regression of data to assist in these studies and also predict the behavior in EqW in the future,
helping in the management of water resources.