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Grandi Laghi Lombardi - HYDROPOWER

Improving 3 Hydropower Plants condition in Ticino Basin by Implementing 2 nonstructural Scenarios


1. Abstract
2. Introduction
3. The Water System Area
    3.1. Current issue
4. Background & Development History
    4.1. Environmental Concerns
    4.2. Flow balancing
5. Method
     5.1. The Scenarios involved to the WEAP Model
        5.1.1. Scenario 1
     First action
     Second action
     Third action
        5.1.2. Scenario 2
     First action
     Second action
    5.2 The Application of scenarios into the  WEAP model
    5.3 Alternative Solutions
        5.3.1. Alternative 0 - Do nothing
        5.3.2. Alternative 1
        5.3.3. Alternative 2
    5.4. Identification of Performance Metrics
        5.4.1. Resiliency, vulnerability and reliability of water demand
        5.4.2. Benefit in billion of €
6. Results
    6.1 Visual results of the affection of other stakeholdes
7. Conclusion
8. Uncertainly
9. References
10. Authors
11. Appendices
APPENDIX A: ENEL hydropower selling prices


This wiki is about a group project related to the management of three hydropower plants Industriale, Regina Elena and Porto della Torre located in the Ticino River basin in the Lombardy Region in the north of Italy, done on 3 June 2015 for the course of Natural Resources Management and Integrated Water Resources Management. The Ticino is a river that flows from the Swiss Alps into the Maggiore Lake, and then flows downstream of it until  reaching the Po River. Its water is allocated over several stakeholders. This report will focus mainly on the demand of hydropower production whereas other sectors including irrigation, environment and flood control are involved, we will present the current situation of the hydropower plants in the area under investigation. 

By the means of Water Evaluation Analysis and Planning (WEAP) software, the water system is modelled in order to obtain the current indicators as a benchmark to evaluate two modelled alternatives. The first scenario is related to deliver a higher amount of water to the energy producer sector in water system, the second one is about to increase the delivered water to hydropower plants in the specific period of year in which the energy price is higher.

The purpose of this report is to understand the trade-off between different sectors exactly flood situation and environmental issue in downstream of Ticino River with hydropower sectors to select the best feasible alternative which is resulted in a more reliable hydroelectric source of energy and increase the energy benefit . 

The result reveals that the 1st scenario by delivering a higher amount of water to the hydropower plants will lead to produce more energy  from the water system while it will worsen the situation of Maize Regina Elena, environmental issues in Ticino River at the downstream, the flood in Verbano lake in inconsiderable extent. It improves the reliability, vulnerability, resiliency of Regina Elena approximately by 34%, 19%, 1.8 million m3/s respectively and the total benefit by 12 billion Euros.


Since many years, the region of Lombardy has enjoyed a favorable situation which this could push the area toward a large amount of water demands from irrigation, civil and industrial use to recreational activities and hydro power production. At this point, the water resource management of Lombardy is almost complex where various stakeholders aim to meet their own water demands for the different purposes.

The existence of the five largest Italian lakes (e.g., Garda, Maggiore, Como, Iseo and Lugano) in addition to several smaller lakes in the Lombardy region have provided the main Italian energy companies (e.g., ENEL, Eni & Italgen) with a great opportunity to invest on the hydroelectric power production in the region. In details, the area of study covers some main hydropower plants (e.g., Porto della Torre plant, Regina Elena Hydropower and Industriale Hydropowers) around Lake Maggiore, the longest Italian lake.

The Ticino river with 248 kms long, is fed by the glaciers of the Alps and later flows through Lake Maggiore, is dammed in Switzerland in order to create hydroelectricity, while in Italy it is primarily used for irrigation (Reynolds 1992) and secondly for hydroelectricity (Piatti). The statistics has revealed that Italian hydropower energy capacity hasn’t been significantly changed since 50 years ago, due to the fact that 90% of hydropower potential is estimated to be exploited already. Importantly, the energy demand of Italy has significantly increased since 1974 (TERNA, 2013).

Even though building a new hydropower plant might look good on paper, it may not work- especially where the costly construction of a new reservoir is not a favorite option. Therefore, the energy production optimization takes priority over the construction of new hydropower plants where the water resource management can simultaneously play a key role in support of a reliable and safe system to guarantee the safety of the waterside residents. In order for this to work, not only is there a need to completely change or sometimes modify the existing water release policy of Lake Maggiore, but also to reprioritize the water demand sectors. When it comes to the hydropower sector for the area under investigation, there are a couple of main challenges that we need to tackle: the first one is the existing conflict between three Industriale Hydropowers plus Porto della Torre vs. Regina Elena plant, where it is not an easy task to make a decision on the amount of the water release in whether to either increase the hydroelectric energy profits or satisfy the energy demand of Regina Elena plant by providing a higher amount of water. The second challenge is how to give our water delivery priorities to Industriale Hydropowers and/or Regina Elena plant vs. other water demand sites including Maize Regina Elena as well as Environmental site at the downstream of Ticino River. In order that the hydropower plants would be capable to generate higher amount of energy, we need to use a higher water capacity of the reservoir. Now the third challenge is raised about the high flood risk that might threaten the future of the study area during a heavy rainfall, where a larger flood control zone is required.

The purpose of this report is to evaluate the effectiveness of two alternatives which include deliver more water to hydropower sectors and releasing more water when the price of energy is higher on the basis of 4 performance indicators: Energy benefit, reliability, vulnerability, resiliency of water demand.

The first performance objective is to improve the energy benefit gained by ENEL SPA. The other performance objectives is to secure a more truth worthy system of a renewable green energy provider for the local community. In the first scenario, the goal is that to generally deliver a larger amount of water to all hydropower sectors. While in the second scenario, the higher energy price, the more water delivery to both Porto della Torre and Industriale hydropowers on account of increasing our total energy benefits. In contrary, when the energy price goes down, our priorities will go to Regina Elena plant, irrigation sites and minimum environmental flow at the Ticino downstream, respectively.

The performance of the WEAP model over the scenarios above has allowed us to evaluate how significantly other water demand sites are effected by setting the hydropower generation as our first preference. Therefore we decide on the applicability of scenarios.

The Water System Area

The area of study (Figure1) will concern three of the lakes of the Grandi Laghi Lombardi region, the Maggiore Lake, the Lake of Como and the littlest Lake Ceresio. Maggiore Lake (with a mean height above the sea level of 193 m, 64.37 km long, and 3 to 5 km wide) and Como Lake (with an area of 146 km2) are two of the biggest lakes in Italy, important point for the management of the hydric resources of the area, but also known by the gorgeous landscape particularly appreciated by the tourists (Bluebook, 2008). Starting from that water bodies, we consider the Ticino river "the most important perennial left-bank tributary of the Po River" (Reynolds, 1992) and Adda "a tributary of the Po river, rising in the Alps near the border with Switzerland and flowing through Lake Como" (Chisholm, 1911).

Figure 1. Map of the area (OpenStreetMap)

Current issue:


The Figure.3  shows the in Italy electric energy demand had been increasing since 1974 to 2005. From Figure 2 it can also be understood that the contribution of hydropower as clean source of energy to italian total electricity energy has been stand in somehow constant level since 50 years ago.

Figure 2.The hydroelectric contribution to total energy production (Terna, 2015)

Figure 3.The red rectangular frame shows that the Italian energy demand had been increased from 1974 to 2005 (Figure source)

Background & Development History

Since the end of the 19th century, the first Italian hydroelectric power stations have been established in Lombardy region, where surface water use has been well developed by covering 1/5 of regional energy demand. 2/3 of the overall concession volumes within the region (2751 m³/s) is the amount of water used for hydroelectricity whose the most significant diversions are concentrated in Adda river basins upstream and downstream of the Maggiore lake (Bluebook, 2008). This explains itself with referring to the significant role of hydropower plants in forming the general picture of water demands of the area. Figure 4 also shows the amount of Lombardia’s hydroelectricity, which it has the largest share in contributing to north Italy’s hydropower electricity production.

Figure 4. Contribute in GW of hydropower energy to all the italian regions (TERNA, 2013)



Environmental Concerns: Although the hydropower system returns water resource unaltered in terms of flow and quality, the main reservoirs in certain mountain areas cause a strong alteration in natural flow and ecological balance of watercourses (LINEE GENERALI DI ASSETTO IDROGEOLOGICO E QUADRO DEGLI INTERVENTI BACINO DEL TICINO>). This may rise the concern about ecological conditions to anticipate whether a minimum flow regime in order to maintain river life integrity even downstream of the most important abstraction points, called “Minimum Vital Flow (MWF)”, is guaranteed (Bluebook, 2008). It implies that MWF as “the flow regime required in a natural watercourse downstream of water abstraction points to maintain vital ecosystem functions and quality conditions” is an important factor that is taken into account to formulate the program for water use and water protection despite high water exploitation levels within the region (LINEE GENERALI DI ASSETTO IDROGEOLOGICO E QUADRO DEGLI INTERVENTI BACINO DEL TICINO).


Figure 5.  Impacts of dams on the environment (Figure source)

It must also be taken into consideration that the construction of dams with considerable capacity is barely envisaged where negative impacts on marvelious landsacpe and environment of the region need to be minimized. This may explain the reason why Lombardy region was the first in Italy to adapt an “Administrative Regulation” on small dams in 1986, and to pass a law on “small reserviors”. This could even guarantee public safety at the same time (Bluebook, 2008). * Watch the video on Natural River/ Poorly Run Hydro/ Well Run Hydro



Flow balancing: When high rain-fall events occur, reservoirs can reduce downstream flooding by taking in water during high flows and releasing it again during low flows (Votruba et al., 1989). During the last years, Lombardy region- with an average annual rainfall volume of 27 billion m³ and with precipitation peaks exceeding 2000 mm/year in Varese area, basin of Lake Maggiore and Orobie ridge has experienced impressive and concentrated events resulting in important flood conditions with huge mass of water running through rivers (LINEE GENERALI DI ASSETTO IDROGEOLOGICO E QUADRO DEGLI INTERVENTI BACINO DEL TICINO). This warns that seasonal variation in precipitation patterns and different climate conditions may lead to a crisis in water use system (Bluebook, 2008). The good news is that the large lake areas of Lombardy have been mostly ideal flood retention areas with a non-excessive level rise even during a flood event over the years, so that large Lombardy lakes become huge flood storages basins. In addition to this storage opportunity, the regional mountain areas host a series of reservoirs which are obtained by construction large dams for hydroelectric generation purposes (ENEL). It is point out that the construction of waterfall dams is the best way to use water resources multiple times (Bolognino). As an example, in Adda river valley, it is observed that storage capacity of hydroelectric reservoirs is at least twice the lake basin capacity (Bluebook, 2008).



The Developed Scenarios: As mentioned earlier, a higher amount of water in the 1st scenario is delivered to Porto della Tore, Regina Elena plant and Industriale hydropower site insisting of three sub run-off hydropower plants Vizzola, Turbigo, Tornavento. The model is developed in a montly scale with WEAP software, based on a GrandiLaghiLombardi model (Cominola, 2015)

Scenario 1

To implement 1st scenario as nonstructural method, some management activities are executed below.

First action

Figure.6 with an average of 93% for the energy capacity has been exploited since 1974 to 2010. Figure.7 also imply that the energy production drops for Industraile hydropower plant in specific years, where the water scarcity happens in the Verbano Lake . To overcome the problem above, we define the first management policy as follows:

Figure 6.  A comparison of the ratio of the total annual energy/ max energy produced by all three Industriale hydropowers from 1974 to 2010.

ّFigure 7.Verbano Water Storage from 1974 to 2010

(April - October): Increase the capability of conserving water in Verbano Lake from 74.6% to 90% of total storage capacity to have access to a larger amount of water in order to be released in the critical situation (e.g., the water lack in Verbano Lake). 

Second action

In order for Industriale hydropowers to reach the energy production to a maximum level (see Fig.6 red line), there is a new water demand of approximately 135 m3/s.

Third action

Reprioritize the system water distribution by defining a  higher priority to Industriale hydropower and Regian Elena plants.

As the result, it is not surprising if these actions worsen the condition of Maize Regina Elena since the major part of water, delivered to Regina Elena channel, was first consumed by Regina Elena plant. In the meantime, this sort of water division to Regina Elena and Irrigation channel also has a side effect on the environmental issues in Ticino River at the downstream due to more water delivery to Regina and Industriale channel at the upstream.

The condition of Maize Industriale site will be also improved since a higher amount of available water is delivered to Industriale channel to earlier meet Industraile plant and Maize Industriale needs fully. The situation for Marzie Virrolesi area also encounters for improvement as increased available water in severe situation due to the increase in storage capacity is sufficient to such extent that after the diversion of water to desired channels the remains would satisfy it more. The flood condition will be also threatened due to a decrease in the flood zone which is done to increase the storage capacity.

Scenario 2

For the 2nd scenario which is also nonstructural way to optimize energy production and increase the trustworthiness of hydropower electric source we execute following actions:

First action

The higher energy price, the more release of water. The lower energy price, the more water conservation. In order for this to happen, apply a series of constraints on the water release policy for Verbano Lake, for example, the water release doesn't exceed 60% of the total storage capacity from April to September when the energy price is low (see Figure 8). And relaxing the limit by 90% of the total storage when the energy price is high. It is important to point out that 10% of the total water capacity is conserved for the future needs according to Hedging rule where managers accept a small (and less costly) shortage now to avoid incurring a large (and very costly) shortage later (Loucks et al., 2005).


Second action

Reprioritize the water distribution. The higher priority goes to Industraile Hydropower and then to other sectors when the price is high (Figure. 8), whereas at the time the price is low and the demand of Regina Elena Hydropower (Figure 9) is high the priority goes to this sector.

Figure 8. Enel  montly weight average selling prices

Figure 9. Regina Elena Plant’s Monthly Demand

In the 2nd alternative, we haven't made any change or modification over the flood zone in Verbano Lake. On the other side, the situation for environmental issues would worsen since not only is less water released, but also more water is allocated to energy sector producers at the upstream.


The Application of  Scenarios into the WEAP Model:

In order to find the better alternative, we analyze three scenarios through Water Evaluation and Planning (WEAP) software (SEI, 2007).

Figure 10. Grandi Laghi Lombardi montly integrated model in the schematic view of WEAP

According to the model, (Figure 10) the lakes can be seen from the GIS layer, schematically represent with a green triangles. They are, starting from the left, Maggiore Lake, Ceresio Lake and Como Lake. From this the rivers sources, represent in with blue lines. As Ceresio has a simple system represent only with Tresa river, the Ticino and Adda had a more complicated system. In particular, Ticino diverted three times, in order to give water to different channels. Starting from the left, there are Regina Elena and Industriale channel, which give water to some hydropower plants and crops of maize which flow the water into groundwater aquifer (represent in green squares). Then, there is Villoresi Channel, which has only an irrigation demand of water. Last, even the Adda system give water only to an irrigation district. For environmental purpose, the flow of these rivers has been monitor, represent in the scheme with purple circle crux.

 Alternative Solutions


Alternative 0 - Do nothing

Keeping the default situation without any changes.

Alternative 1

Our 1st option is to divert more water to hydropower areas. To do so, we increase the top of conservation in Verbano Lake during April to October from 74.6% to 90% of the total storage capacity to have more enough water to release in the critical situation. Then increasing monthly demand for Industriale hydropower plant to 135 m³/s as this amount is maximum flow rate for 3 sub hydropower plants ( Vizzola, Tornavento, Turbigo) which is led to ideally produce maximum hydropower energy. Meanwhile we give the hydropower areas the higher priority to receive water earlier. The 1st priority assigns to Industriale Hydropower and 2nd to the Regina Elena plant . Alternatively, the rest of sectors have a lower priority with the identical level of importance.

 Alternative 2

In the 2nd scenario, we decide to release more water when the price of energy is high to produce more benefit. To do so, we change the buffer coefficient of Verbano Lake in the WEAP model from 1 to 0.6 while the price is low (April to September) and then decrease it from 1 to 0.9 to address the hedging rule. In order that the buffer coefficient is being involved in the calculation all the time we choose the top of buffer as the total storage capacity for the Vebano. Utilizing this action above cause devastating the situation of Regina Elena hydropower plant as the water demand of this site is not almost high when the price of the electricity is high (ّFigure.8). That is where there is a conflict. To mitigate the devastation of Regina Elena condition, we assign the 1st priority to Regina Elena when two events happen simultaneously: 1. The low price signifies less water release 2. The demand water of Regina Elena is high. Thus, it is led to satisfy the water demand of Regina Elena plant at an earlier stage in such condition.


Identification of Performance Metrics

Performance metrics are used to evaluate the efficiency of two alternatives here or better to say how the we are close to our goals. There are four indicators as follows:

Resiliency, vulnerability and reliability of the unmet water demand for Regina Elena Plant

For the Regina Elena demand site, we use the resiliency, vulnerability and reliability of the unmet water demand.

Benefit in billion Euros

For the plants of Porto della Torre, Tornavento, Turbigo and Vizzola we monitor the total income (from 1970 up to 2010) from selling hydropower energy based on a montly weight average of the selling price (Appendix A). The benefit of each above mentioned run-off plant can be calculated toghether  as total benefit because they all belongs to ENEL Energia.


Although the Vizzola, Turbigo, Tornavento represent the Industriale plant, it is in the model as demand site. On the other hand there is no run-off river plant to show the Regina Elena hydropower (Figure. 11). This is because in this way it is  not only possible to define expresion for maximum diversion of water to pass into the Regina Elena, Industriale channels, but also define the priorities of plants easier. In reality, run-off river plants cannot be cansidered as demand sites, because they do not require an amount of water, actually inflow pass through them in order to produce energy so they will not affect the delivery water to other areas while due to the existence of these energy producer demand sites in the model the story is different. this mismatch also leads to show less total benefit as Regina Elena demand site doesn't produce any energy!  

Figure 11. Particular of the WEAP model, Regina Elena Channel


As discussed earlier, the alternatives are assessed on the basis of four metrics. The Reliability of Regina Elena hydropower shows that the time ratio we provided it with sufficient water to produce enough electricity to meet energy demand for which it is supposed to generate. The vulnerability of Regina Elena illustrates the average deviation from threshold which is its monthly demand, when there isn't  enough water to satisfy its need. The resiliency of Regina Elena hydropower shows the chance of when we are in unsatisfied situation, the next step will be satisfied situation. The defined indictors are shown in Figures 12, 13. It is clear from these figures that all metrics are improved for 1st and 2nd scenarios compared to current situation. But for the 2nd choice we get more improvement in satisfying Regina Elena water demand compared to 1st alternative (Figure 12,13). Another indicator is total energy benefit (Figure 14) from hydropower production . While there is improvement in total produced benefit for 1st scenario, the system face with decline in this metric when we implement 2nd alternative.

Figure 12. Resiliency and reliability (%) of Regina Elena demand site for different scenario

Figure 13. Vulnerability (million of m³/s) of Regina Elena demand site for different scenario

Figure 14. Total Benefit of Vizzola, Turbigo, Tornavento and Porto della Torre plants for different scenario



After running 2 scenarios the only worsened sectors  are   Maize Regina Elena, Flood, Envrinmental site at Ticini down Stream. For 1st scenario the maximum flood area is increased just by less than 1%. It also decreases the reliabilty of environmental site at downstream of Ticini by 4.34%. Maize Regina Elena reliability is declined by less than 1%.

For the 2nd scenario Regina Elena Maize encounter with improvement while environmental site reliability is decreased by more than 17%. The flood situation in Verbano Lake face almost with no change.


The current energy issues in study water system are increasing dependency of area on energy and constant level of contribution of hydropower as green source to total energy. The later one explanation in our system is water deficiency in Verbano Lake in severe years and the little gap between the assigned water and capacity of inflow to Industriale hydropower in normal years. Two scenarios have been developed to increase Enel energy benefit and the reliability, vulnerability, resiliency of Regina Elena as hydropower source. First challenge with these two scenarios is the conflict between the two mentioned objectives. Second one is the conflict of benefit and reliability of energy sectors with other aims particularly flood and environmental goals. The 1st scenario gives us better results. It improves the reliability, vulnerability, resiliency of Regina Elena approximately by 34%, 19%, 1.8 million m³/s and total benefit by 12 billion Euros, while it has inconsiderable side effects on flood and environmental sector which seems good as it can be applicable. The 2nd alternative although improves the reliability, vulnerability, resiliency of Regina Elena plant by 36%, 19.3%, 4.7 billion million m³/s but it not only reduces total benefit by 5.47 billion Euros but also worsens the situation of environment in downstream of Ticino river which finally put applicability of the 2nd choice into the question.




Miriam Molteni M.S. Student, Politecnico di Milano, 2015 Como, Italy
Hojjat Borhany M.S. Student, Politecnico di Milano, 2015 Como, Italy


APPENDIX A: ENEL hydropower selling prices

The selling prices of hydropower is not fixed. In particular, ENEL divided the year in three main interval in which the selling price varies. Figures 15, 16 and 17 show the different price that hydropower can assume.


Figure 15. Selling prices in € from October to March from week (above) and week-end (below) (Figure source)

Figure 16. Selling prices in € from April to September from week (above) and week-end (below) (Figure source)

Figure 17. Selling prices in € of August (Figure source)

As the selling price varied much during the day, the aim of hydropower plants is to maximise the production during the interval in which the price is higher, in order to get more benefits.

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