Transcript Hydrology and water resources in the wake of climate change

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
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
1.1 Climate change: Observations and predictions
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
1.1 Climate change: Observations and predictions
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
Climate change impacts /
general
Climate change impacts/
water resources
The hydrological cycle
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
1. WATER RESOURCES IN THE FACE OF CLIMATE CHANGE
1.2 Climate change: Hydrological impacts/Europe
* 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 high
rainfall 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 and
Uncertainties for
Defining
European
Climate change risks and
Effects project
http://prudence.dmi.dk/
1. WATER RESOURCES IN THE FACE OF CLIMATE CHANGE
1.2 Climate change: Hydrological impacts / Germany
Changes in annual mean
temperature, 1750-2003
smoothed with a 11- year
window
Changes in annual precipitation, 1850- 2003 (Baur
curves) smoothed 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 / US/ Canada
CGCM1
CRCM
2100-change in winter precipitation in Canada
Global and regional model
2100-change in median runoff in the US
1. WATER RESOURCES IN THE FACE OF CLIMATE CHANGE
1.3 Climate change: Groundwater resources sustainability / background
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/ water use USA
Trends in population,
groundwater, and surface
water withdrawals.
Withdrawals by sector
Hudson et al. (2004)
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
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 / 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
2.
SYSTEM ANALYSIS OF SURFACE - AND GROUNDWATER RESERVOIRS
2.2 Scales and variability of climate and hydrological systems/ groundwater aquifer
Effects of drought on ground-water levels and associated
subsidence in the San Joaquin Valley, California.
Regional groundwater flow system with subsystems at
different scales
Water elevations in three wells
In a surficial aquifer in Florida
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
3.
MODELING THE IMPACT OF CLIMATE CHANGE ON SURFACE- AND GROUNDWATER
3.1 General issues related of hydro-climate modeling /climate and hydrological models
Types of climate models
Atmosphere general circulation
models (AGCMs)
Ocean general circulation models
(OGCMs)
Coupled atmosphere-ocean general
circulation models (AOGCMs)
Fundamental equations
in 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 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 / hydrological models
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
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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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
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
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
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 /LARS
http://www.rothamsted.bbsrc.ac.uk/mas-models/larswg.php
LARS-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 semiempirical 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.
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.