This year, rain started late in Portugal. Aguieira dam, located 25 km upstream Coimbra (Figure 1) is the main responsible for the Mondego river regulation, the largest in Portugal that is entirely Portuguese. After its construction, floods in Coimbra and in the fields downstream Coimbra are not so often comparing with the old times. However, on 11th January, Aguieira dam had to release water through its spillways (Figure 2). Accordingly to EDP (Portuguese electric company, owner of Aguieira dam), the flow that reached Aguieira was 1200 m3/s and dam used 400 m3/s to produce energy and release more 400 m3/s through its spillways. According to newspaper the flow verified in Coimbra dam (Figure 3) in 11st January was 1470 m3/s and water level increased more than 1 m causing again floods in Coimbra “Parque Verde” (Figure 4) and in fields downstream Coimbra.
Figure 1 – Localization of Mondego river, Agueira dam, Coimbra and Figueira da Foz
Figure 2 – Aguieira dam spillways discharge Figure 3 – Coimbra dam
Figure 4 – Coimbra “Parque Verde” floods (https://www.youtube.com/watch?v=1jIxtf467jk ; https://www.youtube.com/watch?v=yf1TrXk6-00)
It was the highest water level since “Parque Verde do Mondego” exists and several losses in its monuments, bars and restaurants occurred caused by sediments and water in electrical equipment (thousands of Euros off losses) as well as in the fields downstream. Last floods caused by Mondego river were on 27th January 2001 for the discharge of 1910.7 m3/s and in 1948, when, without Aguieira and Coimbra dam, the natural discharge was estimated as 4000 m3/s. TNevertheless, the major losses were caused by 2001 floods in spite of being caused with half water discharge of 1948 floods.
Some try to responsible nature and climate changes, other EDP since it looks always for the most profit generating hydropower. Is that correct?
Nature cannot be responsible! We just have to appreciate it, sometimes try to understand and never hurt it. Leading with floods, 3 causes are always present: 1- river side occupation; 2- lack of maintenance related with accretion and 3- failed in operating hydraulic structures or in plans to preview losses or even disrespect with available studies.
Several studies shows that under level 21 m, all could be flooded occasionally, thus constructions under this level should be provisional or plans to minimize losses should be done and activated when needed. Human floods culture was lost when the river become regulated by the dams, any problem that causes floods should not be endorsed exclusively to one responsable.
In addition, some Mondego tributaries are not regulated, dams construction could be important to regulate flow in those tributaries. Accreation/Erosion of river bed should be monitorized and maintained. Structures to protect areas such as gates, provisional structures constructed with sediments bag, boxes and stop overs, rubber to isolate and avoiding equipment areas flooded should be provided.
Hopefully Quics will visit Coimbra and Parque Verde in 2017.
Rita F. Carvalho