Projecting Climate Change Impacts on Water Resources in Regions of Complex Topography: A Case Study of the Western United States and Southern California

This is the talk given by Jeremy Pal (GS) in Trento on July 26, 2017. He talked about the impact of climate change and  land use on California water resources. Actually the work he presented is part of the awarded Master Thesis of Brianna Pagàn (see last slides).

The talk presents in a plane way the issue related to water resources management of South California, Los Angeles area. It then uses an impressive set of modeling tools to pass from climate and land use changes to water availability. You can enjoy the video and get the slides too.  

 

Here it is the abstract of the talk:

 

The Western United States and California have a greater potential vulnerability to climate change impacts on water resources due to a heavy reliance on snowmelt driven streamflow. California, the most agriculturally productive and populous region in the United States, depends on a complex and extensive water storage and conveyance system to supply water primarily for irrigation, municipal and industrial use and hydropower generation. This study provides an integrated approach to assess the impacts of climate change on the hydrologic cycle and extremes for all Southern Californian water supply basins:  Owens Valley, Mono Lake, Colorado River, Sacramento River, San-Joaquin River, and Tulare Lake basins. An 11-member ensemble of coupled atmosphere-ocean global climate models is first dynamically downscaled using a regional climate model and then statistically downscaled to force a hydrological model resulting in 4-km high-resolution output for the Contiguous United States. Greenhouse gas concentrations are prescribed according to historical values for the period 1976-2005 and to the IPCC Representative Concentration Pathway 8.5 for the near term future period 2021-2050. Precipitation is projected to remain the same or slightly increase by mid-century; however, rising temperatures result in a repartitioning of precipitation type towards more rainfall and therefore a reduced snowpack and earlier snowmelt. In addition to these hydrological changes, daily annual maximum runoff and precipitation events are projected to significantly increase in intensity and frequency such that future return periods change to become substantially more common. More specifically, the current daily annual maximum runoff 10-, 25-, and 50-, and 100-year events are projected to become approximately two to ten times more likely in the future. Furthermore, annual cumulative runoff volumes are projected to increase for high flow years and in contrast decrease for low flow years reducing the reliability of the system. While the escalating likelihood of drought reduces water supply availability, earlier snowmelt and significantly more intense winter precipitation events increases flood risk requiring winter releases from reservoirs for flood control purposes. All of these factors, coupled with projected increases in population, are likely to decrease supply during the higher demand drier months necessitating multiyear storage solutions for urban and agricultural regions as well as improved infrastructure and measures for flood control.
 

Is possible to get the runoff for European Countries ?

This is a conversation between two groups of the CLIMAWARE project of some general interest. Further information about global or continental scale hydrology can be found in some previous posts.

Dear Alberto and Riccardo, 

we are writing about the data we need for the project CLIMAWARE. 

The objective of out analysis is to estimate the impacts on agricolture of modification of:

1)  soil use

2)  anything due to the changed water availability as a consequence of the climate change. 

We are thinking to consider two time frames, the first up to 2020, the second up to 2040 (this because the estimation of soil use variation are available for these two dates and to do an analysis on the national scale for all the Countries of the European Community. 

Martina

Alberto's answer:

Dear Martina,

for what I know, there are not detailed projections at this scale. I saw studies on the largest basins (as  Danube) where all is solved by putting R = P- E (runoff = precipitation - potential evapotranspiration). For what I know, nobody looks at the national scale, for the reasons that the river basins do not coincide with nations areas.

There are regional studies (not about the countries but  for Southern Europe, for instance) made by Giorgi’s group or by Julich’s colleagues using their Earth system model. 

Bruno Majone answer:

Dear Martina,

what you are opening is a Pandora’s vessel. I try to explain it better. To deal with water availability at European scale, there are many different approaches. The simplest is to do a hydrological budget simply by using the available climatic projections. Alternatively, one can use hydrological models working at pan-european scale that can be fed directly by the projections themselves. For any of the choices the real problem is selecting the right forcings. There isn’t a reference dataset: there are various “ensemble” of simulations derived from various climate models, each one of them following a different pathways scenarios.  The reference initiative for Europe is Euro-cordex that gathers the modelling work of various research groups that perform experiments with global and regional climate models, and scale down the results from a coarse grid of 125 km to one of around 25 km (see the pdf). Considering the results of these models one should observe that usually they have strong biases that need to be corrected. Otherwise the water budgets can be extremely wrong. For what I know, inside the Euro-Cordex group there are groups that are examining and providing scenarios by using various techniques of bias correction, but I am not sure that they are already available and usable. 

If your interest is to have annually aggregated data by country, I personally would not explore thid road because I believe that the effort to contact the active groups, download huge datasets and precess them could be overwhelming.

I would try instead to contact groups that already have hydrological models setup at European scale and are already estimating climate change impacts. Alberto mentioned the Julich group, but another possibility could be JRC. They have their model LIFSFLOOD set up at 5*5 km of resolution (and it could be that they already have used it to do some impact studies).  At this point you should ask for they to send some gridded data of runoff and afterwards aggregate them at country level.

Economy, Water, Climate change. Methods and scale of analysis in economy.

This talk, of the CLIMAWARE project series, was given by Martina Sartori, a young economist, part of the group of the project. The talk was the occasion to exchange information about the type of models and the scale of modelling economists use to assess the impacts of variation of water availability on the economic system.

Click on the Figure to get the presentation.
I have to say that the discussion was interesting. The scale economists use is much larger than catchment scale, mostly because their models are parametrised on the knowledge of nations' exchanges more than regional ones. Model themselves seem not to be very complex from the mathematical point of view, but they treat thousands of parameters which makes them complicates. These parameters are collected by specialised companies and/or institutions by sorting out transactions among countries and looking at the global market. Probably the theoretical foundations of these models could not be so unassailable, but, however, they embeds a lot of empirical knowledge. For us was important to talk together.

Fifth Water Conference Selected Presentations on Impacts of Climate Change on Alpine Regions

As any two years, the Alpine Convention organised the a "Water Conference" to assess the results of the Water Platform, which I had the honour to head in 2013-2014.

The fifth Water Conference was entitled: "Water in the Alps - and beyond; Adapting alpine and mountain river basins to climate change".
The event is going to be jointly promoted and developed by the Alpine Convention and the UNECE Water Convention, in order to favour the creation of synergies and the exchange of experiences (i.e. among the Alpine territory, the Carpathians, the Caucasus, Central Asia,...).

The 5th Water Conference is intended to provide to a wide audience of experts, administrators, practitioners and stakeholders the state of the art, the best practices and the main findings about adaptation to climate change in the mountain trans-boundary river basins.
Different panels of experts will illustrate the main results of the last years of activities in the respective conventions.
Furthermore, updated high-level information on climate change and adaptation strategies will be provided, together with the results of some relevant projects of European Territorial Cooperation on the issues.

Finally, a special focus will be devoted to the implementation of the measures of flood management, in the EU flood directive.

The whole set of presentations given during the conference can be found here. However, I would like to bring to attention a few outstanding, related to the impacts of climate change on the Water Cycle:

• M. Beniston,  Changes in Alpine water resources: examples from the EU «ACQWA» Project^1
• A. Bellin, The impacts of climate change on water cycle
• S. Gruber,  The changing mountain cryosphere: impacts on sediment and solute transport
• U. Morra di Cella,  Permafrost in the Alps: the experience of PermaNET project “Long-term permafrost monitoring network”
• G. Rosatti, Modelling sediment transport in Alpine rivers subject to climate changes

^1 AQWA Project

Project CLIMAWARE

Today we submitted the CLIMAWARE project: CLIMatic change impacts on future Availability of WAter REsources and hydro- geological risks.

It is a proposal internal to UNITN but it involves so many different disciplines and Departments that represent a variety that normally can be found only in EU projects. Please below, find the abstract of the project, while we cross the fingers for its approval.

                                       

The pressure of human activities on the earth system, including the water cycle, is multifaceted and intrinsically interlinked with climate change due to the inherent complexity of natural and human processes. The interaction of humans with the environment is strongly non-linear and is dominated by multiple feedbacks and non-stationarities, which are difficult to identify and assess. Despite these complexities, the existing tools to deal with the many hazards connected to the interaction of humans with the environment are based on simple approaches, founded on the concept that the earth system is in a steady state, so that predictions on its evolution can be safely made either statistically, or through simplified models founded on the hypothesis the processes are stationary.
This proposal focuses on the interactions between climate change and human activities related to water, with a holistic view embracing physical, social and economic processes. It will consider, in particular, changes in water cycle components related to extremes and their implications in contiguous sectors. Here extremes include floods and land instabilities triggered by extreme precipitations, such as debris-flows and snow avalanches, but also different stress factors threatening the integrity of freshwater services, with adverse effects on agriculture, tourism, and energy production. New paradigms, approaches and tools will be developed in order to cope with the non-stationarity of water cycle processes and to study the entanglement between the physical processes and human activities. The proposal is interdisciplinary also regarding the physical aspects, and involves interaction between water related disciplines, such as climate science, meteorology, hydrology, fluid mechanics, and information technology for aspects related to distributed monitoring. Because of the challenges that climate change imposes, there is a need to increase general awareness of climate-related risks, and find ways to mitigate the impact on economic activities as well as to adapt to new scenarios. For mitigation and adaptation strategies to be effective, knowledge of the physical aspects of the water cycle should be combined and complemented with knowledge of social and economic processes that crucially affect the use and management of freshwater. Furthermore, it should consider that national governments, on the one hand, and the European Union, on the other, have started to enact laws aimed at countering the effects of climate change. The implementation of these measures and their harmonization with existing laws, however, is not without problems. This might require some legal creativity – and the interaction of law with other hard- and social sciences – to bring about effective results.

Project Description, highlighting the interdisciplinarity (excerpt)

Climate change mitigation and adaptation require substantial changes in production and consumption patterns, as well as in individual behaviors. This is particularly true for water- related sectors, which are a linchpin in the production of beverages, food and energy, and for many recreational activities. However, in economics, estimates of water resource availability are rarely made on a solid quantitative basis. Also, the systematic preemptive estimation of extremes caused by hydrological events is a science in its infancy. The recent advances in hydrology and water related sciences open interesting perspective for new methods and models to support a better informed decision making process at all levels, from local to national and international. Moreover, societal and economic concerns receive only marginal attention in the debate [1]. Arguably, the gap between science, society and policymakers undermines the decision-making process.

The interdisciplinary approach of this project, which combines insights from hard sciences with sociology, economics and law, represents an important step towards bridging the gap between science and society, and raising awareness of the benefits of cooperation between disciplines. The project studies the complex interplay between physical and human processes in controlling the distribution, in space and time, of water resources by considering both actual and possible future climatic and societal scenarios. The project is organized in five interconnected Tasks (Figure 1): Task 1 evaluates the drivers of water resource availability; Task 2 assesses climate change and human impacts on water resources and local hydro-geological extremes (underestimated according to a report by WMO [2]); Task 3 addresses the development of suitable tools for describing and modeling environmental granular flow extremes and sediment transport; Tasks 4 and 5 aim for better management of water resources, specifically, Task 4 uses the paradigm of virtual water to assess the regional impact of the food trade, while Task 5 tries to envisage effective societal responses to climate change.

A full description of the project, financed by UNITN5, can be found here.

References

1. Malnes, R.; Environmental Politics 17(4), 660-672, 2008.
2. http://www.wmo.int/pages/prog/drr/transfer/2014.06.12WMO1123_Atlas_120614.pdf