hydrology and water resources in wake of climate change manfred koch department of geohydraulics and...

Hydrology and Water Resources in Wake of Climate Change

Manfred Koch

Department of Geohydraulics and Engineering Hydrology, University of Kassel, Germany

Email: [email protected]

SEAN-DEE Seminar

Kassel University, November 9, 2012

mailto:[email protected]

Overview

1. WATER RESOURCES IN THE FACE OF CLIMATE CHANGE

1.1 Climate change: Observations and predictions

1.2 Climate change: Hydrological impacts

1.3 Climate change: Groundwater resources sustainability

2. SYSTEM ANALYSIS OF SURFACE - AND GROUNDWATER RESERVOIRS

2.1 Basics of water budget analysis and implications on sustainable water management

2.2 Scales and variability of climate and hydrological systems

3. MODELING THE IMPACT OF CLIMATE CHANGE ON SURFACE- AND GROUNDWATER 3.1 General issues related to hydro-climate modeling

3.2 From global to local scale: downscaling from the climate to the hydrological model.

4. CONCLUSIONS

1. WATER RESOURCES IN THE FACE OF CLIMATE CHANGE 1.1 Climate change: Observations and predictions

1. WATER RESOURCES IN THE FACE OF CLIMATE CHANGE 1.2 Climate change: Hydrological impacts / general aspects

The hydrological cycleClimate change impacts / general

Climate change impacts/water resources

1. WATER RESOURCES IN THE FACE OF CLIMATE CHANGE 1.2 Climate change: Hydrological impacts/global

1. WATER RESOURCES IN THE FACE OF CLIMATE CHANGE 1.2 Climate change: Hydrological impacts /global

* Most General Circulation Models (GCMs) predict a strong change in rainfall over the the Northern hemisphere with wetter winters and drier summers in Northern Europe

• GCM results indicate increases in both the frequency and intensity of heavy rainfall events under enhanced greenhouse conditions

• In Northern Europe these changes will cause a 10 to 30 percent increase in the magnitude of rainfall events up to a 50 year return period by the end of the century

• One of the most significant impacts of such changes may be on hydrological processes and, particularly, river flow

• Changes in seasonality and an increase in low and highrainfall extremes, such as droughts of the 1990s and floods of 2000/01 severely affect the water balance of river basins.

* This will influence the rate of available water resources, as well as the frequency of flooding and ecologically damaging low-flows.

Summer precipitation change in % for 2070-2100 relative to 1961-1990

1. WATER RESOURCES IN THE FACE OF CLIMATE CHANGE 1.2 Climate change: Hydrological impacts/Europe

PRUDENCE:

Prediction of Regional scenarios andUncertainties for Defining EuropeanClimate change risks andEffects project

http://prudence.dmi.dk/

1. WATER RESOURCES IN THE FACE OF CLIMATE CHANGE 1.2 Climate change: Hydrological impacts / Europe

Changes in annual precipitation, 1850- 2003 (Baur curves) smoothed with a 11- year window.

Changes in annual mean temperature, 1750-2003smoothed with a 11- year window

1. WATER RESOURCES IN THE FACE OF CLIMATE CHANGE 1.2 Climate change: Hydrological impacts / Germany

Regional Climate Model REMO (Meterological Institute, Hamburg, Germany)

REMO model prediction of temperature changes in 0C and winter and summer precipiation for 2071-2100 relative to 1961-1990

1. WATER RESOURCES IN THE FACE OF CLIMATE CHANGE 1.2 Climate change: Hydrological impacts/Germany

1. WATER RESOURCES IN THE FACE OF CLIMATE CHANGE 1.2 Climate change: Hydrological impacts / US/ Canada

CRCMCGCM1

2100-change in winter precipitation in CanadaGlobal and regional model

2100-change in median runoff in the US

Climate change could affect ground-water sustainability in several ways, including

(1) changes in ground-water recharge resulting from changes in average precipitation and temperature or in the seasonal distribution of precipitation,

(2) more severe and longer lasting droughts,

(3) changes in evapotranspiration resulting from changes in vegetation, and

(4) possible increased demands for ground water as a backup source of water supply.

Surficial aquifers, which supply much of the flow to streams, lakes, wetlands, and springs, are likely to be the part of the ground-water system most sensitive to climate change; yet, limited attention has been directed at determining the possible effects of climate change on shallow aquifers and their interaction with surface water.

1. WATER RESOURCES IN THE FACE OF CLIMATE CHANGE 1.3 Climate change: Groundwater resources sustainability / background

Trends in population, groundwater, and surface water withdrawals.

Withdrawals by sector

Hudson et al. (2004)

1. WATER RESOURCES IN THE FACE OF CLIMATE CHANGE 1.3 Climate change: Groundwater resources sustainability/ water use USA

Overview










4. CONCLUSIONS

2. SYSTEM ANALYSIS OF SURFACE - AND GROUNDWATER RESERVOIRS 2.1 Basics of water budget analysis and implications on sustainable water management

dS / dt = Qin - Qout

Total water balance : dST / dt = P + Qswi – ET – Qswi /Integrated model---------------------------------------------------------------------------------------------------------------

Surface water balance: dSS / dt = P – ET – O – I /Surface water model

Vadose zone balance: dSV / dt = I – R /Vadose zone model

Groundwater balance: dSG / dt = R + Gin – Gout - Qp /Groundwater model)

2. SYSTEM ANALYSIS OF SURFACE - AND GROUNDWATER RESERVOIRS 2.1 Basics of water budget analysis and implications on sustainable water management / IWRM

2. SYSTEM ANALYSIS OF SURFACE - AND GROUNDWATER RESERVOIRS 2.1 Basics of water budget analysis and implications on sustainable water management/ seawater intrusion under human and climate impact /concepts

2. SYSTEM ANALYSIS OF SURFACE - AND GROUNDWATER RESERVOIRS 2.1 Basics of water budget analysis and implications on sustainable water management/ seawater intrusion under human and climate impact / Florida case study

2. SYSTEM ANALYSIS OF SURFACE - AND GROUNDWATER RESERVOIRS 2.2 Scales and variability of climate and hydrological systems /atmosphere and ocean

2. SYSTEM ANALYSIS OF SURFACE - AND GROUNDWATER RESERVOIRS 2.2 Scales and variability of climate and hydrological systems /precipitation and streamflow

Monthly precipitation and wavelet spectrum in Hamburg

Monthly discharge and wavelet spectrum of Elbe river close to Hamburg

Effects of drought on ground-water levels and associated subsidence in the San Joaquin Valley, California.

2. SYSTEM ANALYSIS OF SURFACE - AND GROUNDWATER RESERVOIRS 2.2 Scales and variability of climate and hydrological systems/ groundwater aquifer

Regional groundwater flow system with subsystems at different scales

Water elevations in three wellsIn a surficial aquifer in Florida

Overview










4. CONCLUSIONS

Fundamental equationsin climate models

Atmosphere general circulation models (AGCMs)

Ocean general circulation models (OGCMs)

Coupled atmosphere-ocean general circulation models (AOGCMs)

Types of climate models

Numerical discretization in AOGCMs

3. MODELING THE IMPACT OF CLIMATE CHANGE ON SURFACE- AND GROUNDWATER 3.1 General issues related of hydro-climate modeling /climate and hydrological models

Historical development of climate models

Synopsis of GCMs (starting point for all impacts studies, due to anthropogenic forcing):

Advantages: information physically consistent, long simulations + different SRES scenarios, many variables, data readily available;

Disadvantages:coarse-scale information where regional or local-scale climate information is essential, daily characteristics may be unrealistic except for very large regions, computationally expensive

3. MODELING THE IMPACT OF CLIMATE CHANGE ON SURFACE- AND GROUNDWATER 3.1 General issues related of hydro-climate modeling /climate models

3. MODELING THE IMPACT OF CLIMATE CHANGE ON SURFACE- AND GROUNDWATER 3.1 General issues related of hydro-climate modeling / hydrological models

Why downscaling?

Because there is a mismatch of scales between what global climate models can supply and what hydrological impact models require.

3. MODELING THE IMPACT OF CLIMATE CHANGE ON SURFACE- AND GROUNDWATER 3.2 From global to local scale: downscaling from the climate to the hydrological model

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Rayong Province


1. High resolution and variable resolution AOGCM time-slice experiments - numerical modelling

2. Regional Climate Models (RCMs) - dynamic downscaling

3. Empirical/statistical and statistical/dynamical models - statistical downscaling

Fowler, H. J., S. Blenkinsopa and C. Tebaldi, Linking climate change modelling to impacts studies: recent advances in downscaling techniques for hydrological modelling, Int. J. Climatol., 27, 1547–1578, 2007


SDSM (transfer function/ weather typing)https://co-public.lboro.ac.uk/cocwd/SDSM/

3. MODELING THE IMPACT OF CLIMATE CHANGE ON SURFACE- AND GROUNDWATER 3.2 From global to local scale: downscaling from the climate to the hydrological model /SDSM

https://co-public.lboro.ac.uk/cocwd/SDSM/

http://www.rothamsted.bbsrc.ac.uk/mas-models/larswg.phpLARS-WG/stochastic weather generator

allows the generation of daily data from monthly climate change scenario information.

Advantage of using a stochastic weather generator is that a number of different daily time series representing the scenario can be generated permits risk analyses to be undertaken.

Steps involved:

1) Analysis of the weather generator parameters, i.e. the statistical characteristics of the data, precipitation, maximum and minimum temperature, sunshine radiation. Use of semi-empirical distributions calculated from the observed data, for wet and dry series duration, precipitation amount and solar radiation. Temperatures described using Fourier series.

2) Generation of synthetic weather data using the parameter files generated in step (1) for the observed data record length, or to simulate longer time series of data . For generation of daily data for a particular climate change scenario the appropriate monthly changes are included.

3) Statistical test (chi-squared test, Student's t-test and F-test) of the characteristics of the observed data are compared with those of synthetic data generated using the parameters derived from the observed station data.

3. MODELING THE IMPACT OF CLIMATE CHANGE ON SURFACE- AND GROUNDWATER 3.2 From global to local scale: downscaling from the climate to the hydrological model /LARS

http://www.rothamsted.bbsrc.ac.uk/mas-models/larswg.php

4. CONCLUSIONS

Effects of potential long-term changes in climate, caused either by man-made adverse activities or by natural climate variability of internal or external origins on water resources, namely, groundwater - which is most likely become the major source of water for human consumption, as surface water resources are on the demise – has been discussed with regard to its availability, sustainability and its counterpart, vulnerability.

Climate change could affect groundwater sustainability in several ways, including

(1) changes in groundwater recharge resulting from seasonal and decadal changes in precipitation and temperature,

(2) more severe and longer lasting droughts,

(3) changes in evapotranspiration due to changes in temperature and vegetation,

(4) possible increased demands for ground water as a backup source of water supply or for further economical (agricultural) development,

(5) sea water intrusion in low-lying coastal areas due to rising sea levels and reduced groundwater recharge that may lead a deterioration of the groundwater quality there. This appears to be situation for the Bangkok coastal aquifer system

Because groundwater systems tend to respond much more slowly to long-term variability in climate conditions than surface-water systems, their management requires special long-term ahead-planning.

4. CONCLUSIONS (cont. 2)

Coupled hydro-climate models are needed to predict climate one or more decades ahead into the future to assist in rational planning of water resource systems as water needs change. It is important that these models predict trends at the decadal time scale, but also provide an indication of the permanence of these changes to distinguish permanent changes from rather temporary excursions.

Some challenges and further research needs to better understand the effects of climate variability and change on future water resources availability may be summarized as follows:

• evaluating and improving global climate models in terms of the most critical parameters for hydrology, such as extremes of precipitation, and evapotranspiration incorporating humidity, cloudiness, and radiation;

• better representation of yearly- to decadal-scale climate variability in global climate models through representations of driving mechanisms such as El Nino, the Inter-decadal Pacific Oscillation for the Pacific region and the Northern Atlantic Oscillation (NAO) and the Arctic Oscillation for the northern Atlantic hemisphere

• reducing uncertainty in climate projections through further research into methods of determining and narrowing uncertainty for particular applications such as hydrology;

• studies to separate anthropogenic-induced changes from natural climate change and variability by also including high resolution paleo-records of hydrological and climatological parameters and analyzing them with modern methods of stochastic time series analysis;

4. CONCLUSIONS (cont. 3)

• further development and application of downscaling methods that represent climate at the relatively fine spatial and temporal scales of landscape hydrology;

• better representation of the continental physical hydrology in global climate models to simulate the interactions between climate and hydrology;

• better understanding of large-scale physical hydrology and its effects on the subsurface recharge process to be able to project future hydrological behavior for unprecedented climate conditions;

• improving the understanding of the interactions of groundwater with land and surface water resources by developing better integrated surface water/groundwater models;

• get a better hold on the importance of feedbacks through vegetation on hydrology and how these might change under future climate and CO2 concentrations;

• increased use of remotely sensed data for climatological and hydrological applications as from the very promising GRACE earth satellite project.

In conclusion, proper consideration of climate variability and change will be a key – at present still underemphasized - factor in ensuring the sustainability and proper management of water resources and groundwater in particular. The achievement of this goal will require more collaboration across the fields of climatology and hydrology, as more reliable methods for water planning that provide planning certainty for water users under the impact of climate change must be developed.

hydrology and water resources in wake of climate change manfred koch department of geohydraulics and...

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