Resumen
Paute River basin is located in southern Ecuador, has an area of 5066 km2
and an elevation range of 1840-4680
m a.s.l. Its importance relay in different water uses as human consume for the city of Cuenca (near 400.000
inhabitants), irrigation, industry and an important hydropower plant for nearly 30% of the national system energy.
Rainfall perturbations found in 1963-1993 period cause decadal oscillations of precipitation, which identifies the
climate variability of the region. Positive perturbation belong to wet period and the negative belong to dry period,
and between both there are transition periods. These oscillations seem to have influence of regional weather patterns
such as ENSO. Consequently, the importance in knowledge of spatial and temporal variability of rainfall and it
extremes is necessary for a better water resources management. Further, unimodal precipitation region (UM) with
one yearly rainy season at the eastern basin, and bimodal precipitation region (BM) with two rainy seasons at the
western and middle part of the basin explain the complexity of rainfall spatial variability.
Therefore, this study analyses extreme rainfall events at 10 rain gauges sites distributed along the basin for the
complete period of records (CPR), its wet and dry periods, and transition periods. Gumbel, Gamma and the LogPearson type III probability distributions were used to assess yearly annual maximum events of each rain gauge
record, the best fitted was chosen. Subsequently, extreme events of each site and for all analysed periods were
compared. In addition, the analysis of IDF curves considering the Merrill Bernard and the Wenzel models was
performed.
It was found that yearly annual maximum events in the eastern basin (UM) are better described by the Gamma
type distributions. On the other hand, the Gumbel distribution performed better for rain gauges at the middle and
western basin at higher elevations (BM). However, the adjustment of any probability distribution also depended of
the period analysed. In general, for wet periods the three-parameter Gamma distribution was better adjusted.
The magnitudes of the wet period extreme events were higher than extreme events of the CPR, and much higher
than the dry period ones. However, there were two rain gauges sites as exemption. This exemption is due to
the presence of high magnitude events of El Niño phenomena during the analysed period, which influenced the
probability distribution performance.
The 50-year return period event of dry and wet periods are equivalent to 15-year and 133-year return period of the
CPR, respectively. In addition, it was evidenced the existence of hysteresis in two of the four rain gauge located at
the central part of the basin (BM).
The Merrill Bernard model best describes the precipitation performance at the eastern part of the basin (UM),
while in the central-western and highest part of the basin the Wenzel model fits better. In general, IDF equations
determined for each period and station revealed that rainfall intensity magnitude of wet period is 25% higher than
dry period’s one, with the complete series magnitude between both.
and an elevation range of 1840-4680
m a.s.l. Its importance relay in different water uses as human consume for the city of Cuenca (near 400.000
inhabitants), irrigation, industry and an important hydropower plant for nearly 30% of the national system energy.
Rainfall perturbations found in 1963-1993 period cause decadal oscillations of precipitation, which identifies the
climate variability of the region. Positive perturbation belong to wet period and the negative belong to dry period,
and between both there are transition periods. These oscillations seem to have influence of regional weather patterns
such as ENSO. Consequently, the importance in knowledge of spatial and temporal variability of rainfall and it
extremes is necessary for a better water resources management. Further, unimodal precipitation region (UM) with
one yearly rainy season at the eastern basin, and bimodal precipitation region (BM) with two rainy seasons at the
western and middle part of the basin explain the complexity of rainfall spatial variability.
Therefore, this study analyses extreme rainfall events at 10 rain gauges sites distributed along the basin for the
complete period of records (CPR), its wet and dry periods, and transition periods. Gumbel, Gamma and the LogPearson type III probability distributions were used to assess yearly annual maximum events of each rain gauge
record, the best fitted was chosen. Subsequently, extreme events of each site and for all analysed periods were
compared. In addition, the analysis of IDF curves considering the Merrill Bernard and the Wenzel models was
performed.
It was found that yearly annual maximum events in the eastern basin (UM) are better described by the Gamma
type distributions. On the other hand, the Gumbel distribution performed better for rain gauges at the middle and
western basin at higher elevations (BM). However, the adjustment of any probability distribution also depended of
the period analysed. In general, for wet periods the three-parameter Gamma distribution was better adjusted.
The magnitudes of the wet period extreme events were higher than extreme events of the CPR, and much higher
than the dry period ones. However, there were two rain gauges sites as exemption. This exemption is due to
the presence of high magnitude events of El Niño phenomena during the analysed period, which influenced the
probability distribution performance.
The 50-year return period event of dry and wet periods are equivalent to 15-year and 133-year return period of the
CPR, respectively. In addition, it was evidenced the existence of hysteresis in two of the four rain gauge located at
the central part of the basin (BM).
The Merrill Bernard model best describes the precipitation performance at the eastern part of the basin (UM),
while in the central-western and highest part of the basin the Wenzel model fits better. In general, IDF equations
determined for each period and station revealed that rainfall intensity magnitude of wet period is 25% higher than
dry period’s one, with the complete series magnitude between both.
| Idioma original | Español (Ecuador) |
|---|---|
| Publicación | Geophysical Research Abstracts |
| Estado | Publicada - 2019 |