Thanks for the invitation. Representing IDB and Walter who could not attend and sends his regrest
Key objective is to partially respond to the question: Just read bullets
There is some evidence that hydrology is changing and that stability os being lost. For example in the Grijalva basin located in the state of Tabasco in Mexico: Important basin with significant economic relevance Just read the bullets
Many Andean glaciers have been retreating , and some of them could completely disappear over the next 10-20 years. Warming in the Andes is also already causing severe damages to high mountain ecosystems, including the drying of páramos (a unique type of wetland found in the northern Andes) and the disappearance of snowcapped terrain. These ecosystems have unique endemic flora and provide numerous and valuable environmental goods and services. Major population centers including Bogotá and Quito, depend on páramos for their water supply In Bolivia, Ecuador, Peru, Colombia, and Venezuela glacier retreat could seriously affect seasonal water flows and the availability of water for human consumption, hydropower, agriculture, sanitation, and ecosystem integrity. Reduced glacial runoff in the Andes is likely to cause severe water stress for up to 77 million people by 2020. Additional investments to ensure continuity of water supply in Quito (Ecuador) could reach US$100 M. over the next 20 years. Andean countries are highly dependent on hydropower (more than 50 % of electricity supply in Ecuador, 70 % in Bolivia, and 80 % in Perú) and much of it is dependent on water from glacial runoff. Significant investments will be required to maintain generation capacity. For example, estimates of the incremental costs to Peru’s power sector range from $212 million if gradual adaptation is used, up to $1.5 billion under rationing.
Temperature anomalies are becoming the norm in the Andes and the upper watersheds of major basing in South America Graph shows how maximum and minimum temperatures are increasing, for instance at the Las Brisas Station at 3500 m in the central range fo the Andes in Colombia With temperature increases there is an increase incidence of mountain fires, which have negative implications for water retention in soil.
To simulate at high resolution the impact of climate in hydrology, the earth simulator in Japan, has been used. It is the second fastest scientific high yield computer available to climate simulations. It uses the MRI Global circulation model and produces high resolution simulations of future climate It is one of 23 models being used under the IPCC 5 th assessment report
MRI, is now engaging in a project “Extreme event projection with super-high-resolution atmospheric models.” Here 20-km mesh global model is used for the present, near future and end-of the-century simulations. For the regional climate change, it also uses regional cloud resolving model, which is nested into the global 20-km mesh model. It produces data on projected extreme events at a very high resolution (20 meters and 5 meter gird)
This graph shows the result of the simulation under A1B scenario for projected intensification of rainfall. It shows the projected anomaly in downpours anticipated by end of century As can be seen all over south america, rainfall is anticipated to be concentrated and the anomaly is highest in central Brazil, northern argentina and the coastal areas of peru and ecuador, which show an increase in 5 day downpours of up to 40 mm of raindall or more,
Likewise, the simulation projects a lengthening of dry periods, here the longest additional extension of dry periods (extension of 30 or more days with no rainfall are projected for central and north east brazil and the coasts of peru and northern chile by the end o century. Both the concentration of rainfall in short period and the lengthening of dry periods, contribute to an overall invrease in the stability of hydrological regimes.
Another projected effect is the projected seasonal reduction in top soil moisture.
When a simulation is made of seasonal rainfall in the Amazon basin (For example, data shown here indictes projections for the archimedes station in the amazon state, the model projects a significant reduction in rainfall during june to august, contributing to extreme dry conditions during the dry seasons
Dry period rainfall disappears, together with other changes impacts stream-flows, thus, potentially affecting many services. The graph shows simulation of high and low flows for portobelo and obidos on the rio madeira and amazon rivers. The red line indicates projection to end of century and the blue line for mid century. The model shows an increase in high flows and a decrease in low flows (in m3 per second) as time progresses
The model has been used to simulate change in absolute flows in the upper watershed of the amazon basin, for end of century. It shows an annual projected reduction in total flows in percentage (right panel),
Conclusions, read bullets
Walter Vergara and Simone Bauch, IDB
Climate change impacts on hydrological cycle ADVANCING SUSTAINABLE HYDROPOWER IN LATIN AMERIC A NOVEMBER 12 2012 WALTER VERGARA AND SIMONE BAUCH CLIMATE CHANGE AND SUSTAINABILITY DIVISION
Will future climate affect the integrity and stability of hydrology? Climate trends may be unbalancing the hydrological cycle in major regions of Latin America; extreme floods and period of severe droughts are being registered with increased frequency; and, in association with land use changes, may be shifting existing hydro power firm capacity and changing its structure and behavior. These changes could also have implications for regional and global carbon and water cycles. Use of the Earth Simulator (high speed, high resolution nested model) could discern projected changes in hydrology in large basins
Extreme hydrology: Grijalva Basin in Mexico• 40% of all runoff in Mexico and 30% of all hydro power generation.• The hydrology in the basin is destabilizing: 4 100 year floods in the last 20 years.• Impacts on settlements and economic activities are not controlled.• The costs to the States of Tabasco and the border area with Guatemala have exceeded 4% of GDP
Loss of Glaciers in the Andes Andean glaciers retreat: Impacts from loss of water regulation would affect human water supply, agriculture, power generation and ecosystem integrity
Temperature increase and fire eventsin the central range of the Andes(Las Brisas)
The Earth Simulator IPCC 5th assessment report MRI Global circulation modelhttp://www.jamstec.go.jp/es/en/index.html 819.2 Gflops x 160 = 131 Tera flops
Projection of changes in hydrology with the Earth Simulator Atmosphere- High-resolution Regional cloud Ocean model global atmospheric resolving model model by nesting 180km mesh 20km mesh 5km & 1km mesh Atmos Predicted Atmos Boundar phere SST phere y condition SST SST Boundary Ocean condition Future 100-50km mesh Near Future Present SST=Sea Surface SST Temperature Year 7 1979-2003 2015-2039 2075-2099
Projected intensification ofrainfall (future-present 5 day max)
Projected increases in length of dry periods in days (future-present)
Projected seasonal changes in top soil moisture (%)
Projected changes in dry season rain in the Amazon basin
Changes in river flows: a) current annual flows (mm) and b) change between the present and the end of the century (%)Note: The picture a) presents the absolute annual flow and therefore the scale is in mm. The picture b) presents the change, and the scale is in percentage.
Conclusions and next stepsAbility of upper-shed basins to regulate water Need to assess the impacts at a flows may also be compromised by loss of basin level so that adaptation glacier cover and mountain wetlands responses can be designed;Fire events will further reduce water retention by vegetation in mountain areas. Need to strengthen resiliency ofFuture climate may bring increased frequency of water supply and power extreme rain and also lengthen the duration generation systems to minimize of dry periods net impacts in reliability ofFuture climate is likely to be associated with service reductions in moisture in top soil layersIn the aggregate all of these changes can affect the stability of hydrology and thus have impacts in all depending services, including firm capacity of hydro power reservoirs, water supply for agriculture and human settlements and others