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5
Conclusion
T
he climate and hydrology of the HKH region melt occurs during a dry season; (ii) glacier meltwater
are changing. There are many important uncer- flows into semi-arid areas; and/or (iii) small annual
tainties about the current state of physical and temperature cycles mean that there is little seasonal
variation in snow cover. Conversely, the seasonal ef-
social systems in the region in addition to the uncer- fect is smaller where there is significant precipitation
tainties about the future. However, not everything is during the melt season, such as the monsoonal central
uncertain or unknown. It is important to consider the and eastern Himalaya.
impact of glacial retreat on regional water resources
Melting of glacial ice plays an important role in
in the larger, hydroclimatic and social context of the
maintaining water security during times of drought or
HKH region. The effects of climate changes on glacier
similar climate extremes. For example, in the European
dynamics will affect both the supply and demand for
Alps during the drought year of 2003, glacial melt
water in the Himalayan region, and these changes will,
contributions to August discharge of the Danube River
in turn, affect the vulnerability of key populations to
were about three times greater than the 100-year aver-
freshwater problems. Glacial retreat is only one factor
age (Huss, 2011). Thus, water stored as glacial ice is
that contributes to changes in the hydrological cycle,
the region's hydrological "insurance," acting as a buffer
and the relative importance of glacial meltwater var-
against the hydrological impacts brought about by a
ies across the region and between seasons. In most
changing climate, releasing the stored water to streams
instances, the contribution to surface-water discharge
and rivers when it is most needed.
of snowmelt exceeds that of glacial melt. Glacial melt
There may be normal, even increased, amounts of
does contribute to the water flow in major rivers such
available meltwater to satisfy dry season needs because
as the Ganges and Indus, but for low-lying areas such
of the release of "insurance" water from storage in
as the Gangetic Plain, at much lower percentages than
retreating glaciers for the next several decades (Barnett
thought several years ago. The effect of glacial retreat
et al., 2005). To illustrate, the role of glacial wast-
will be most evident during the dry season, particularly
age contributions to discharge under future warming
in the west. In all seasons, changes in many regions are
scenarios was investigated for three highly glacierized
likely to be dominated by shifts in the location, intensity,
catchments in the Alps that have long-term climate
and variability of precipitation (both rain and snow)
and discharge records (Huss et al., 2008). Annual run-
rather than glacial retreat. Glacial meltwater is not a
off from the drainage basins shows an initial increase
major contributor for river systems to the east but is
which is due to the release of water from glacial stor-
more important for river systems to the west. Kalten-
age. After some decades, depending on catchment
born et al. (2010) conclude that,
characteristics and the applied climate change scenario,
In general, the impact of melting glaciers on the sea- runoff stabilizes and then drops below the current
sonal distribution of river flow is greatest where (i) ice level. Retreating glaciers of the HKH in the short
93
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94 HIMALAYAN GLACIERS: CLIMATE CHANGE, WATER RESOURCES, AND WATER SECURITY
term (decadal time frame) will subsidize surface flows Although economic development could reduce adverse
by melting water held in storage, mitigating immedi- outcomes, including loss of life, monetary loss could
ate losses to discharge by retreating glaciers (Kaser et increase.
al., 2010).
As noted in Chapter 2, paleoclimate records sug- A WAY FORWARD
gest a mixed record of wetness and dryness during the
20th century in the monsoon-dominated eastern HKH When considering the link between humans and
and hydrological modeling indicates that glacial melt is the environment in the context of water security in the
not a major contributor to river systems in the east (i.e., HKH region, four themes emerge: (1) there is signifi-
the Ganges, Yangtze, and Yellow). Thus, for the east- cant variability in the climate, hydrology, and glacier
ern HKH, these factors could result in little change to behavior as well as the demographics and water-use
annual surface-water discharge, but could result in the patterns of the region; (2) uncertainties exist and will
loss of "insurance" water that glacial melt provides for continue to exist in both the physical and social systems;
water security during times of drought. In the western (3) to reduce and respond to this uncertainty there is a
HKH, paleoclimate records indicate a trend toward need for improved monitoring of both the physical and
wetter conditions in the 20th century and hydro- social systems; and (4) in the face of uncertainty, the
logical models indicate that glacial melt is much more most compelling need is to improve water management
important in the west (i.e., the Indus Basin). Thus, the and hazards mitigation systems.
consequences of climate change to water security could Theme 1: There is significant variability in the climate,
be large if a reduction in available surface water either hydrology, and glacier behavior in the region as well as the
annually and/or seasonally occurs in the western HKH. demographics and water-use patterns within the region.
However, the trend toward wetter conditions in the The retreat rates of Himalayan glaciers vary over time
western HKH confounds this assessment. and space, with the rate of retreat being higher in the
During situations such as these, groundwater, a east than the west. There are confounding factors such
significant amount of which is supplied to the major as dust and black carbon that will affect glacial melt
river plains of the region by the Himalayas, will be and in some cases increase glacial wastage. Changes
looked to as a source to offset water scarcity. Thus, in the monsoon will probably be more important than
water security issues for lowland populations over the changes in glacial wastage at lower, downstream eleva-
next decade are more likely to come from overdrafting tions. Rates of urbanization vary across the region,
of groundwater resources than changes in discharge as does the portion of the population with access to
from retreating glaciers. improved water and sanitation.
Although a greater understanding of the glaciers Theme 2: Uncertainties exist and will continue to
of the HKH region will inform knowledge about exist in both the physical and social systems. The impact
water security in the region, improved understanding of future climate change is uncertain but will probably
of the science of the glaciers is itself not sufficient to accelerate rates of glacial retreat. Accelerated glacial
answer all questions about the relationship between retreat rates will have significant impacts in local, high-
the hydrology, the population, and the policies and mountain areas but will probably not be very important
politics of the region. As discussed in Chapter 3, social downstream. As the region's population becomes more
changes are affecting water use at a greater rate than urbanized and standards of living change, water-use
environmental factors are affecting the availability of patterns will also change in ways that will be difficult
water. For example, rising standards of living, includ- to predict. Existing demographic methods to not allow
ing improving and changing diets and greater energy for projections at sufficient spatial resolution to deter-
use, will have a significant effect on water-use patterns mine whether, for example, certain basins and elevation
over the coming decades. Even if streamflow remains zones will experience higher rates of population growth
relatively stable in the short term, human factors could than others and how the demographic composition of
lead to water scarcity. Changing standards of living those specific areas will change. In both the physical
could also influence vulnerability to natural hazards. and social systems, stationarity--the assumption that
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CONCLUSION 95
the systems will fluctuate within a known range of priority. These needs are critical to more fully address
variability--will no longer apply. In other words, the the questions in the Committee's charge.
past is not a good basis for prediction, and past trends
in the climate, hydrology, glaciers, and population of Physical Geography
the region will not be a viable guide for the future (e.g.,
Milly et al., 2008). The HKH is one of the least-observed regions on
Theme 3: To reduce and respond to this uncertainty, Earth. Currently available data lack the necessary spa-
there is a need for improved monitoring of both the physi- tial and temporal resolution, as well as quality, to fully
cal and social systems. Monitoring will need to occur understand the region. There is a need for carefully
on a more extensive and consistent basis. Without designed surface observing systems (including tempera-
enhanced monitoring, the information needed to ture, precipitation amount and type, streamflow, glacial
respond to changing environmental and social condi- mass balance, glacier albedo, groundwater, paleoclimate
tions will be unavailable. Monitoring and research proxies) that are integrated with satellite observations
will further understanding of both the physical and to provide comprehensive monitoring of the region.
human systems in the region, and identify the various In addition to new data, pooling of existing data and
options available to respond to change in the face of resources, including release of relevant classified or
uncertainty. restricted satellite imagery or water data, and sustained
Theme 4: In the face of uncertainty, the most compel- international cooperation and data sharing are critically
ling need is to improve water management and hazards important to advance understanding and reduce uncer-
mitigation systems. Existing patterns of water use and tainties. Comprehensive monitoring and data sharing
water management need improvement. As discussed in would help answer the following questions:
Chapter 3, some progress has been made in improved
assessments in the recent past. Going forward, improved · Climate, meteorology, and aerosols: What are the
implementation of lessons from these assessments in effects of greenhouse gas warming and black carbon
water policies and programs will be necessary. Options radiative forcing on winds, temperature, precipitation
for adapting to climate change are discussed in greater variability, and trends in the summer monsoon and
detail in the next section. However, the people most mid-latitude westerlies? How much of the regional
likely to be affected by changing water security in South atmospheric aerosol loading is driven by local emissions
Asia are the rural and urban poor who have the least compared with transport from remote sources? How do
capacity to adapt to changing environmental and social black carbon deposition, snowfall, and snow turnover
conditions and hazards. Management of groundwater processes combine to affect the albedo of glaciers and
and demand-side management are among the areas snowpack? How has the temperature in the mid and
where improvements can be made. lower troposphere changed? How do current changes in
the regional climate compare to natural climate changes
RESEARCH AND DATA NEEDS that occurred in the past? How will the monsoon
change in the future?
Anticipating future conditions in the HKH region · Glaciers: What is the relationship between cli-
is hindered by an incomplete understanding of current mate changes and the mass balance of the HKH gla-
conditions and of both the extent to which natural ciers? What is the response time of individual glaciers
feedback mechanisms will generate new equilibria to climate forcing, and how does this response time
and human systems will adapt to signals of stress and vary among glaciers in the region? Have temperature
change. As discussed throughout the report, many open changes in the mid and lower troposphere affected the
scientific questions remain about the physical and social equilibrium line altitude or the ratio of snow to rain?
systems of the region, which, if addressed, could lead to How does snow cover change seasonally?
a greater understanding. These research and data needs · Hydrology: What is the relative contribution,
are presented in roughly the same order as the topics seasonally and annually, of glacial wastage and melt-
appeared in the report, and the order does not indicate water to total streamflow in the major rivers of the
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96 HIMALAYAN GLACIERS: CLIMATE CHANGE, WATER RESOURCES, AND WATER SECURITY
HKH region? What are the surface water-groundwater of floods, droughts, heat waves, and secondary impacts
recharge mechanisms in the region? How will climate associated with climate variability. Although deaths
change affect groundwater supply? How can hydrologi- and numbers of persons affected are regularly reported,
cal data become more widely accessible to the science and to a lesser extent physical damages (e.g., houses and
and management communities? How can remote sens- infrastructure destroyed), rigorous economic damage
ing be used in conjunction with well data to increase and need estimation are a priority for policy research.
understanding of groundwater in the region? Disaster resilience, recovery, and reconstruction pro-
cesses are less well documented than initial impacts,
Human Geography in part because they occur when postdisaster attention
wanes. The human dimensions of loss and reconstruc-
Currently available demographic compositional tion require intensive field research, and strong rela-
data do not conform to geophysical parameters and lack tionships between research and practice. New methods
the necessary spatial resolution to determine whether, of postdisaster mobile phone survey data transfer and
for example, certain basins and/or elevation zones will mapping have considerable promise for advancing
experience higher rates of population growth than socioeconomic lines of research on a regional scale.
others. Current understanding of water usage is poor Improved economic, social, and political datasets would
because of a lack of regional datasets. Remote sens- help answer the following questions:
ing advances may address some of these deficiencies,
particularly in the plains. Improved measurement of · Natural hazards and vulnerability: Which popu-
water withdrawals from surface water, and even more lations in the region will be most vulnerable to a
so groundwater pumping, will be crucial for develop- changing climate? What are the proximate and root
ing, monitoring, and managing regional water budgets, causes of vulnerability in the HKH region? How do
hazards, and stresses. As lowland water and energy alternatives for secure and sustainable livelihoods dif-
scarcity may increase demand for mountain water stor- fer for populations in the mountains more dependent
age, advances in water use analysis will have increasing on glaciers and larger downstream populations on the
importance. Improved datasets and monitoring would plains? How can the results of collaborative research
help answer the following questions: on exemplars of disaster-resilient settlement, infra-
structure, and housing in mountain environments of
· Demographics: How will populations change in the HKH region complement initiatives to increase
areas with water scarcity as compared with areas with collaboration on climate change, glaciology, glacial lake
sufficient water supplies? outburst flood monitoring, and flood warning--and
· Water-use patterns: How can major improve- help increase the prospects for successful adaptation to
ments in water-use data collection, access, and utiliza- changes in climate and hydrology in the region? How
tion be accelerated? How do changing lifestyles, stan- can early-warning systems be used to minimize deaths
dards of living, and demographic trends affect water from hazards such as GLOFs?
supply, demand, and management? · Security dynamics and water conflict: What is
· Water management: What dams are planned in the current and future institutional capacity to absorb
the region, and how will they affect water manage- change at the local, national, and international levels?
ment and hydrology? How can the results of inter- How can the research community design appropri-
national- and national-level climate assessments be ate metrics to monitor the capacity of governmental
incorporated into water management and policy at the institutions to address water stress? Does water stress,
subnational level? among other stressors, affect state stability? Through
what mechanisms? What are the possibilities for better
Environmental Risk and Security incorporation of scientific information about glaciers,
hydrology, and climate change into international
Hazard datasets remain inconsistent and not coded water-sharing treaties? Will climate change impacts
in ways that enable causal analysis of large-N samples on glacial melt and hydrology be severe enough to
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CONCLUSION 97
constitute a threat to water and food security and/or (i.e., they would be good strategies to take regardless
political stability? of how severe climate change's impacts become). In
general, many strategies that encourage good manage-
OPTIONS FOR ADAPTING TO ment of water resources under current climate could
CHANGES IN CLIMATE, HYDROLOGY, serve as useful adaptation strategies in a world with
AND WATER AVAILABILITY altered climate. Similarly, because people with fewer
resources are often more vulnerable to climate change
There are some potential adaptations that govern- disruptions, many strategies that promote sustainable
ments, communities, or individuals may consider in economic development could also be useful adaptation
response to climate change's effects on the hydrologic strategies in the face of climate change.
system. Even with significant international progress There is a large literature on the topic of adapta-
toward mitigating greenhouse gas emissions, with tion, and the Committee can only briefly describe
current levels of carbon dioxide and other greenhouse a few potential adaptation options in this section.
gases in the atmosphere, there will be significant cli- Adaptation was discussed previously in the context of
mate change over the next few decades, and thus some water management institutions and disaster agencies in
adaptation, particularly to strengthen water manage- Chapters 3 and 4, respectively. Here, the Committee
ment systems, will be necessary. describes options that affect the supply or timing of
It can be difficult to make decisions about which water available to users, followed by options that affect
adaptation strategies to pursue in the face of uncertainty the demand of water by users. Then the Committee
about the magnitude of climate change's hydrological discusses integrated watershed management and river
impacts. Also, there are significant uncertainties about basin management, which often consider both supply
the effectiveness of various adaptation options. Some and demand. Finally, the Committee discusses adap-
adaptation options have been shown to be effective in tation options to decrease the risk of negative impacts
adapting to variability under current climatic condi- from flooding.
tions, but it is not known whether they will hold up
under a changing climate (NRC, 2010a). Additionally, Adapting Under Uncertainty: The Need to Monitor
implementation of adaptation strategies can be chal-
lenging in developed countries: As discussed above, and throughout this report,
Numerous attempts have been made to develop and lack of understanding and a paucity of data about
implement adaptive management strategies in envi- current and emerging conditions of glacial melt and
ronmental management, but many of them have not the hydrological system more generally are major
been successful, for a variety of reasons, including sources of uncertainty in the region. Adaptive man-
lack of resources, unwillingness of decision makers to agement1 of water resources depends critically on
admit to and embrace uncertainty; institutional, legal, observations of changes that are occurring. Therefore,
and political preferences for known and predictable
outcomes; the inherent uncertainty and variability adaptation options will rely on expanding the moni-
of natural systems; the high cost of implementation; toring programs in the region, including increased
and the lack of clear mechanisms for incorporating hydrometeorological data; measurements of glacial
scientific findings into decision making. Despite all of mass balances, seasonal snow cover, black carbon on
the above challenges, often there is no better option snow and ice; assessment of GLOF risks; streamflow
for implementing management regimes. . . . (NRC, data (i.e., discharge); water quality; and demographic
2011b)
patterns of water use. Both remotely sensed and in
And developing countries are likely to face as many situ data are valuable for such monitoring programs
challenges. (USAID, 2010).
Good first adaptation strategies to pursue are gen-
1 Adaptive management is a flexible approach designed to meet
erally flexible (i.e., they do not lock a country or other
management goals under a variety of future climate conditions
entity into a long-term commitment to the strategy), and requires a nonstationary view (e.g., Milly et al., 2008; NRC,
are relatively low-cost and are "no regret" strategies 2010a, 2012b).
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98 HIMALAYAN GLACIERS: CLIMATE CHANGE, WATER RESOURCES, AND WATER SECURITY
In addition to uncertainties in the physical sys- New dams, either at a large or a small scale, are one
tems of the region, there are also uncertainties in the way to increase hydropower and/or storage in both the
social systems. Adaptive management of the region's Indus and the Ganges/Brahmaputra, although any new
water resources will require a greater understanding dam construction would likely be a politically contro-
of how each option will affect downstream users, the versial decision, both within a country and between
potential negative consequences of each option, and countries. Because climate will be changing over the
whether an option may prove to be maladaptive. In long term, dam planning needs to include multiple
addition, it will be necessary to monitor the impacts scenarios over the projected life of the dam to ensure
of adaptation policies, and make adjustments to the its usefulness under climate change. As well as the
policy as required. Interventions that can be repurposed potential for being maladaptive over time, dam con-
and customized are especially desirable when operat- struction could also have unintended and cumulative
ing under conditions of uncertainty and change. The negative consequences on the regional ecology, settle-
capability to support and integrate interventions into ments, and downstream sediment supply (e.g., NRC,
local innovations that are effective is also of great value. 2011a). Additionally, geological instability limits the
Effective program evaluation, something that is often stability of major dams and reservoir development in
overlooked, is especially important when designing the region and adds risk from dam failure. In any event,
and implementing interventions under conditions of dam management regimes at existing dams will need to
uncertainty. A central concern with adaptation strate- be altered, so that, rather than being operated on the
gies is their potential for changing power relationships basis of historical distribution of streamflow events,
and introducing conflict, and for creating unrealistic dam operation is based on the current (altered) climate.
expectations that can become difficult to manage and Because changes in dam management will affect the
a source of significant social tension. Some manage- availability of water to downstream users, either in
ment and adaption options in the face of hydrological the same country as the dam or a different one, such
change may themselves detrimentally affect water changes may have the potential for conflict if decisions
availability for downstream riparians, possibly sparking are not made cooperatively with all affected parties.
or exacerbating water conflicts or political tensions. More local-scale catchment systems can store water
In other words, the rational pursuit of otherwise rea- in wet seasons for use in dry seasons. Catchments are
sonable adaptation options (e.g., the construction of often constructed and managed at the local level. They
more water storage or the expansion of irrigation) as are relatively less expensive, lower impact, and easier to
insurance against prospective climate-induced short- change than large dams.
falls or volatility in future supply could have negative Another adaptation option sometimes used in the
consequences. face of water shortages is to construct a system for
interbasin water transfers, moving water from a rela-
Supply-Side Strategies tively wet place to a relatively dry place. Such systems
are often extremely expensive to construct, such as the
One potential impact of climate change on the Chinese plan to divert water from south China to the
region's hydrology is to increase the frequency of both north, the South-North Water Diversion Project, which
high-flow events and low-flow events. One adaptation is estimated to cost around $62 billion dollars (Wong,
option is to try to increase storage, so that water can be 2001). Moreover, any plan by upstream countries for
stored during wet periods for use during dry periods. an interbasin transfer in the Ganges/Brahmaputra
Three approaches to this effort are improved water sup- Basin would likely have international political repercus-
ply forecasting, dams, and catchment systems. In each sions and could be the basis for a conflict. Interbasin
approach, the need for flexible systems that can adapt water transfer is further complicated by the lack of
in a range of uncertain futures suggests that small- understanding of the impact of climate changes on the
scale and low-cost systems may be the best options for hydrology of the region. Changes in the flow of rivers
at least the planning horizon of most countries and in the relatively wet areas could impair their ability to
donors. adequately provide water for the dry areas, decreas-
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CONCLUSION 99
ing the effectiveness of a very expensive project. For (Box 3.1) may serve as a climate change adaptation,
these reasons, proposals for interbasin water transfers but success depends on the level of community cohe-
are generally controversial among hydrologists, policy sion and will be limited unless enough groundwater is
analysts, NGOs, and the courts. available for the system. Because available data indicate
Usually, climate change adaptation is considered a the groundwater is currently being used unsustainably
separate topic from climate change mitigation (i.e., the in the region, this adaptation option, by itself, is likely
reduction in emissions of pollutants that cause climate not realistic; however major advances in conjunctive
change). Greenhouse gas emission mitigation is by management of surface and groundwater will be a high
necessity a global challenge, because most greenhouse priority.
gases are well mixed in the atmosphere. However, for There are also options for local water storage. For
South Asian countries the control on the emission of instance, some high-altitude communities in the HKH
aerosols and particulate matter could help mitigate region have experimented with building small ponds
the regional pattern of climate change, because these that freeze in the winter into miniglaciers (ICIMOD,
pollutants play an important regional role in, respec- 2000b). These miniglaciers then melt slowly over the
tively, the monsoon cycle and the rate of snowmelt growing season, providing farmers and towns with
and icemelt. Although the exact scientific relationship water. Larger reservoirs could potentially become a
between these pollutants and regional climate is still an hazard due to earthquake-induced failure, or change
area of active scientific exploration, there is potential the energy balance of snow-covered basins. Addition-
that countries could cooperate to maintain traditional ally, there are emerging technologies that harvest water
climate patterns to some extent by limiting emissions of from humid air (ICIMOD, 2000a). An increasing
aerosol and particular matter. Because actions by a small number of cities in South Asia are adopting harvest-
set of countries could significantly change the regional ing requirements in building and development codes
concentration of these pollutants, such an agreement (Agarwal et al., 2001). Another way to increase water
could avoid the problem facing many global agreements supply at the local level is to reuse treated wastewater
about greenhouse gas pollutants, where there are many (e.g., Kumar et al., 2005), particularly for irrigation.
actors who have to approve an agreement. Reducing Given the uncertainty in the future magnitude of
aerosol emissions is also a resilience-building strategy, climate change impacts, one general adaptation option
in that it has the co-benefit of reducing respiratory dis- is to expand the diversity of techniques that are used
eases and premature deaths, especially among women to obtain water. The idea is that instead of just one
and children (NRC, 2010b). source, which could be critically affected by climate
One common adaptation strategy used to address change, multiple sources would be relatively less sensi-
short-term water shortages is to withdraw ground tive to disruption by climate change, unless climate
water. Groundwater is a form of water storage, and can change were to impact all the sources simultaneously
be sustainably used as long as withdrawal rates do not and synchronously.
exceed recharge rates of the aquifer. However, changes
in the regional hydrology could affect the recharge Demand-Side Strategies
rate, leading to uncertainties in the amount of water
that can be sustainably withdrawn. Increased use of Any strategy that increases water-use efficiency can
groundwater may be one adaptation to climate change, serve as a potential climate change adaptation, but can
but some major aquifers are already being depleted by also increase a population's vulnerability if users do not
excess withdrawals, so there are (often uncertain) limits see the value in using less water. Because users some-
to how extensively increasing withdrawal from ground- times expand their use to take advantage of increased
water can be a long-term adaptation to climate change. water availability, efficiency gains do not always trans-
In addition, groundwater withdrawal in delta regions late into reductions in total water use. These gains may
could lead to increased subsidence, which in turn leads still increase the productivity of a given water use per
to increased sea level rise. Increased use of the tradi- unit of water withdrawn and hence a sector's resiliency
tional karez or qanat system of channeling groundwater to climate change. The agricultural sector is the biggest
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100 HIMALAYAN GLACIERS: CLIMATE CHANGE, WATER RESOURCES, AND WATER SECURITY
user of water, and the one with the greatest potential for ments to account for further changes in precipitation
increases in water-use efficiency to serve as an adapta- patterns. The focus of adaptation strategies might also
tion. For instance, cotton, rice, and sugarcane irrigation be how to reduce irrigation demands during extreme
in the Indus Basin use a large volume of water, and low-flow periods of the year. Although forgoing irriga-
small reductions in the amount of water used per hect- tion during low-flow events imposes an economic cost
are could significantly reduce water use by these crops. on farmers, it may leave enough water in surface water
Another sector where gains in water-use efficiency and groundwater for downstream users. However, this
may be helpful in adapting to climate change would may have a negative impact on regional food security,
be the energy sector. Thermoelectric power plants that again demonstrating the complexities of adaptation
use once-through cooling systems withdraw signifi- options.
cantly more water than recirculating cooling systems.
Although most of this water is discharged to the stream River Basin Management
after use, there can be local thermal impacts. A switch
from once-through cooling to recirculating cooling can The ideal model for river basin management
significantly reduce water withdrawals by the sector. and the processes its development, management, and
However, recirculating systems have higher consump- maintenance have been given considerable thought and
tive use than once-through systems, so trade-offs are have evolved through time (Molle et al., 2010; NRC,
necessary (NREL, 2003). Municipal water systems also 2010c). Embedded within this discussion is the concept
could improve technological efficiency, perhaps as part of environmental flow (EF) that describes the water
of extending their coverage to growing populations. regime (quantity, timing, and quality) within a system
Such adaptation strategies require large infrastructure that is required to maintain the surrounding ecosystem
investments, which affect their feasibility. and human livelihood. Most EF assessments have been
There are a number of tools available to affect developed and performed in developed countries. Yet
demand management. Some of these are technology assessment of EFs in developing countries, such as
based and include flow restrictors, low-flush toilets, those in the HKH region, is a necessary step toward
closed conduit irrigation systems--sprinkler and drip successful river basin management, and some progress
systems--and water metering, either by itself or in has been made (Smakhtin et al., 2006).
connection with rational regimes of water pricing. In Often, water managers implement minimum
general, the relatively high capital costs of these tech- EF requirements based on system objectives such as
nologies make their adoption prohibitively expensive maintaining populations of fish at a given level or
for much of the water-using population in the region. supplying local communities and/or agriculture with
More decentralized demand management techniques a given volume of water (NRC, 2010d). When a river
include water pricing and water rationing. Shah (2009) basin is at the point where there is no more utilizable
describes how the availability of complementary inputs flow in a given year, the basin is said to be "closed"
such as energy for pumping groundwater have been (Falkenmark and Molden, 2008). If a basin is closed
used successfully to manage demand for irrigation and utilization continues, an unsustainable situation
water in some areas. This is accomplished by making ensues. The waters of the Indus and the Ganges are
energy available only during certain periods of the day. already said to be overallocated or nearing overalloca-
These decentralized demand management techniques tion, thus "closed" basins (Falkenmark and Molden,
have the advantage of allowing each user to adjust con- 2008; Smakhtin, 2008).
sumption according to their circumstances. Efforts to effectively manage river basins attempt to
More significant climate change impacts on hydrol- avoid this type of situation and the associated impacts
ogy might necessitate changes in land use over time. such as a decrease in water quality or inequitable shar-
For instance, farmers might adapt to climate change ing of the resource. It is increasingly being realized that
by shifting from a water-intensive crop that requires the biological and social systems supported by water
significant irrigation to a less intensive, perhaps rainfed, are not adequately described by a single minimum flow
crop. Such a strategy would require periodic adjust- requirement or a set of flow requirements, but a more
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CONCLUSION 101
comprehensive assessment of water management is for water management and health (clean water and
needed that accounts for hydrological change (NRC, sanitation) (USAID, 2010).
2012b). This would include, for example, basic strate-
gies such as demand management, increased storage, Managing Flood Risks
establishment of EFs, and operational flexibility (NRC,
2012b). The first step in reducing potential flooding
One option, integrated watershed management impacts from climate change is to map which com-
(IWM), attempts to consider both demand- and munities are at risk (NRC, 2009). The primary risk
supply-side strategies for managing water in a basin of flooding from glacial melt per se is GLOFs, which
to find a solution to any water problems in the basin. are mostly a risk to high-elevation communities
Although definitions of IWM vary, the general focus along rivers and streams, but similar phenomena can
of management is on looking at all uses of water pose risks at lower elevations when debris or ice jams
simultaneously when making policy decisions. For the dam water that then bursts out. In contrast, the risk
Ganges/Brahmaputra and the Indus, there is a clear of downstream flooding may be increased by climate
need, for example, to link management of surface-water change, depending on a number of factors including
resources more closely with management of ground- the rate and timing of snowmelt and the magnitude
water resources. There is also a need for management of monsoonal rains. Because there are many large
decisions to be made that consider the needs of water settlements near rivers in the lower floodplains of the
users in different countries. This is often a difficult task Ganges/Brahmaputra and Indus basins, if climate
politically, but the existing international agreements change increases the risk of downstream flooding
(e.g., Indus Water Treaty) illustrate that agreements events, it could significantly affect hundreds of mil-
about water allocations can be achieved. lions of people.
Many of the international agreements in the region Once communities at risk from flooding are iden-
are not yet fully integrating climate change consider- tified, there are various options that can be used to
ations into their decision making, and any progress on minimize risk, although many are very difficult to
this front could serve as a climate change adaptation, implement. New development can be limited in flood-
by ensuring that basin water resources are managed plains or other sensitive areas, or existing homes and
efficiently and equitably in a changing climate. Climate infrastructure in floodplains at risk of flooding can be
change planning at the national level is important. Even decommissioned. Vegetation, including forests, can be
if many national hydrological agencies are considering restored where needed to retain water and thus miti-
the potential impacts of climate change, many other gate flooding. Governments can offer flood insurance
national government agencies are not. If, for instance, programs, as the Federal Emergency Management
agencies deciding on the construction of new irrigation Agency's National Flood Insurance Program does in
systems are not adequately considering the effect of the United States, both mandatory in high-risk areas
climate change in their decisions, then countries may and nonmandatory in low-risk areas. Alternatively,
commit significant resources to irrigation that will not new infrastructure can be built to protect areas at risk
be useful in a future climate. of floods (e.g., dams, pumping stations, or storage
At national and subnational levels, opportunities basins). Sometimes this infrastructure is traditional
exist to provide knowledge and assistance to farmers "gray" infrastructure, such as levees. However, levees
in efficient water use, especially as regards irrigation are often considered to be maladaptive, because they
systems. Local or subnational organizations, networked can encourage settlement in vulnerable low-elevation
for greater impact, can develop farm-level and coopera- areas (NRC, 2012b). In other cases, so called "green"
tive strategies for both groundwater and surface-water infrastructure solutions are used, where floodplains are
use. Another adaptation option includes establishing reconnected hydrologically with rivers to allow flood
or strengthening community-based water user associa- waters to spread out over the entire floodplain. This
tions (WUAs) and forest user groups (FUGs), with reduces the flooding risk to downstream communities
better coordination links to national policy frameworks by reducing the height of peak flows in a river.
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102 HIMALAYAN GLACIERS: CLIMATE CHANGE, WATER RESOURCES, AND WATER SECURITY
Flood management also includes early warning mate change are already more extensive than previously
systems, which can reduce deaths and injuries, and thought or recognized, and are mounting more quickly
disaster response capacity, which is highly variable and more extensively than predicted. This suggests that
in the region. Improvements in each of these areas in discussions of climate change impacts over 50-year-
would be adaptive to both glacial melt and hydrologi- plus time horizons may have to be replaced with
cal change. ten-year-plus time horizons, and more comprehensive
There is a growing sentiment within parts of the approaches to hydroclimatic forecasting, natural haz-
climate science community that the social effects of cli- ards mitigation, and water management.
