1. Water Resources Management for Climate
Change Adaptation and Sustainable
Water Security
N. H. Rao
XIII Agricultural Science Congress, Bengaluru, 2017

2. Outline
Water security – definition and status
Climate change - trends over India
Climate change and water resources
Science and policy framework for climate smart water security

3. Water insecurity among top three risks for global economy
Water security
Water security: availability of acceptable quantity and quality of water for health, production, livelihoods and ecosystems, coupled with an acceptable level of water-related risks to people, environment and economies
Water security = f (demographic, economic, land use, technological, environmental change, tolerable water related risk for society)
Water security is about managing two types of risks across scales:
Access risk for productive services
Destructive risk for human and natural systems
Water security is about managing two types of risks (access, destructive) at a tolerable level for society, across local to global scales
Water insecurity among top three risks for global economy
(WEF, 2017)
Grey and Ladoff (2008); Grey, 2016

4. Absolute scarcity: < 500 M3
Water security status: National Water Balance
Per Capita water availability
Range for river basins
1600 M3 (2010)
1139 M3 (2050)
<300 - >14000 M3
1000 M3 = average per capita water requirement (drinking, hygiene and growing food) Water stress: M3 Water scarce: M3
Absolute scarcity: < 500 M3
11 of 20 river basins currently water stressed/water scarce/abs scarcity
Surface storage capacity 250 BCM ~ 200 m3/capita (world average: 800 m3/capita; China 2500 m3/capita; USA: 6000 m3/capita)
Adapted from: CWC, 2016; Water Data Book

5. Water security status: water availability
Groundwater anomaly trend
Surface water availability (m)
Groundwater availability (m)
Rainfall (mm)
Surface water availability is higher, but groundwater dependence is very high
Groundwater draft: 245 BCM in 2011 (~ total surface storage); 90% for irrigation; covers > 60% irrigated area; responsible for 70% of production
Groundwater meets 85% of rural and 80% of urban water needs
Groundwater aquifers are highly stressed in Northern India
water table declining by 20mm/yr during
Groundwater depletion in N-W India = 40mm/year (highest in major aquifers of world)
In 60% of Blocks, groundwater development is critical/unsafe or water quality is poor
Adapted from: CGWB 2015; World Resources Group – India Water Data Tool, 2015; Asoka et al, 2017

6. Average rainfall for the period
Water security status: water stress (rain deficit) and storage requirement
NDI <1; small local intra-annual water storage will suffice
NDI > 1; medium annual carry over storage or groundwater can meet deficits of worst droughts at specified risk levels
NDI > 5; districts have chronic multi-year water stress
large surface storage or groundwater needed to meet multi-year drought deficit
corresponding districts currently have canal irrigation & critical levels of groundwater exploitation
Normalized Deficit Index
Even without climate change:
water security in many regions is at risk
risks will increase and spread to more regions as water demand increases with population & and incomes (~ 70% by 2050)
Normalized deficit Index (NDI) = Maximum accumulated water deficit in a district in n years
Average rainfall for the period
(n = 104 years)
adapted from : Devineni et al, 2013

7. Climate change intensifies water insecurity
Median return period in 21st century for discharge corresponding to the 20th century 100-year flood
Climate change alters the hydrologic cycle:
Alters soil moisture, surface flows & groundwater recharge patterns
Increases variability of water supplies
Increases risk of extreme events (rainfall intensity, hot temperatures, floods, droughts)
Small changes in temperature and rainfall are amplified in river flows and extremes
Groundwater recharge responds more steadily to precipitation changes
Increases pressure on surface water infrastructure
Water security is about managing risks across local to regional scales
Fig source: IPCC, 2012; Hirabayashi et al, 2013

8. Climate projections to 2100 - Temperature
Annual Mean Temperature increases ( 2030 to 2100):
2.0 to 4.8 for BAU
°C (RCP2.6)
More increase in night temperature and post monsoon
Increase in frequency of extreme temperatures (1‐in‐20 year hottest day likely to become a 1‐in‐2 year event)
Consecutive day warm spells beyond 90th percentile, lengthen to 150–200 days under (BAU), but only to 30–45 days under RCP2.6
Fig source; Chaturvedi et al, 2012

9. Climate projections to 2100 - Rainfall
Mean annual precipitation: increases 4-5% by 2030s; % by 2080s; except for a few regions in short term projections (2030s); increase in inter- annual variability
Years with above normal monsoon rainfall expected to increase
Extreme precipitation: increase in frequency of extreme precipitation (>40 mm/day) days for 2060s and beyond; 30-40% increase in frequency of > 100 mm/day events
1‐in‐20 year annual maximum daily precipitation likely to become a 1‐in‐5 to 1‐in‐15‐year event by the end of the 21st century
Frequency and intensity of droughts increase in lower latitudes
Frequency and intensity of floods increases
Fig source; Chaturvedi et al, 2012

10. Climate change impacts on water resources – streamflow in major basins
RCP 4.5
RCP 8.5
In majority of river basins, streamflow likely to increase
Monsoon season streamflow increase > 40% in 8/9 basins for RCP 4.5/RCP8.5
Streamflow is more sensitive to changes in rainfall than temperature
Evapotranspiration increases up to 10% in both scenarios
Source: Mishra & Lihare 2016

11. Climate change impacts on water resources – drought (moderate(1,2), moderate to severe (3,4))
estimates based on weekly soil moisture deficit
increase in moderate and severe drought frequencies and areal extent despite increase in rainfall (marginal improvement towards end of century)
Source: Gosain et al, 2012

12. Climate change impacts on water resources – extreme flows, dependable flows
Extreme flows (99th percentile) increase by 10-50% leading to flooding in majority of the river basins; few sub-basins show some decrease in the peak flows
dependable (10th percentile) flows also increase; in some basins in central India dependable flows decline
Substantial efforts required to develop future water management strategies
Source: Gosain et al, 2012

13. Climate change impacts on groundwater
strategic importance of ground water for water security will intensify under climate change because:
high dependence and storage capacity
frequent and intense droughts and floods
increasing vulnerability to abstraction – particularly in the IGB
affected more slowly than surface flows
Sustaining groundwater under climate change will require adaptive water management that
accounts for spatial and vertical heterogeneities in aquifers
leveraging opportunities for natural and artificial groundwater recharge (managed aquifer recharge)
Adapted from: CGWB 2015; McDonald et al, 2016, Asoka et al, 2017

14. The state-of-art of the science for climate smart water management
Climate change projections: spatial resolutions and data
Climate change hydrology
CMIP 5 GCMs (spatial resolutions of km ) predict quite well annual mean temperature and precipitation and extremes
Increasing confidence in CORDEX/RCMs downscaled predictions to 50/25 km resolutions for regional applications
Downscaled information at finer resolutions relevant to hydrologic modelling becoming feasible with big data methods (NASA, Climate Corp)
Issue: easy/free access to authenticated high resolution climate data for hydrologic studies
High resolution hydrologic models for Indian river basins including runoff generation, water balance and streamflow routing increasingly available
CWC & NRSC's WRIS provides geospatial hydrologic products at 16.5 km resolution on surface runoff, evapotranspiration, soil moisture and river discharge with two-day time lag
Groundwater hydrology and quality not so extensively explored and researched in India
GRACE, ESA-CIC and SWOT satellite data on groundwater levels, soil moisture and surface water available in public domain
Daily 5m resolution satellite products available for land use monitoring from microsatellites (Planet.com)
Issue: data access on flows, groundwater levels, hydrogeology, water quality; access to authenticated high resolution digital data on topography, land use, soils, river flows, groundwater levels, water quality

15. Guiding principles for framework for operationalizing climate smart sustainable water security in India
Water security in India is equally concerned with green water (soil water), and blue water (surface and groundwater) as over 60 mha will be rainfed
Groundwater recharge management is key to future water security
A one size fits all approach does not work as climate, natural resources, water use vary spatially
But one-water concept is central
Climate smart water security management framework must :
be based on scalable typologies representative of spatial heterogeneities
be informed by high resolution data and scalable, integrable climate-soil water-surface water- groundwater hydrologic models
identify and leverage opportunities for natural and artificial groundwater recharge, and augmentation from other sources to mitigate risks
Digital watershed atlas of India is a source for such typology and scaling of model outputs

16. Framework for water security
CWC provides national scale, 9 min (16 km) grid-wise surface runoff, evapotranspiration, soil moisture data estimated with two-day time lag since 01 Jan 2014

17. To conclude :
Globally, the state-of-art of climate, water and other sciences can :
provide evidence to identify and assess water-related risks for a water security
make the case for investment in risk reduction
But the effectiveness of the science to deliver water security depends on:
Scientific and institutional capacities to absorb and apply the science:
create the data networks for data generation and access
develop new interdisciplinary and innovation competencies
(bridging the data and technology valley of death)
Policies that:
encourage rapid adoption of technologies for efficient water use
ensure timely action and adaptation towards risk reduction
enable free access to data and models to enhance the capacity of science to provide improved solutions
allow leveraging digital India capacities for data generation and access, and technology transfer

18. Thank You