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Water Management for
Climate Change Adaptation
Jeanny Wang Miles
IRAS Water management and water harvesting to support agricultural adaptation to climate change
~ Debriefing Workshop / Vientiane, Laos / Jan. 14, 2013~
Water
Availability
and Water
Harvesting
in Laos
Jeanny Wang Miles
(EcoWang)
Climate Influences
Global Water Availability
Mekong
River
(Laos)
Laos
- Entirely within Mekong
River Basin (25%)
- 202,000 km2 watershed
- Landlocked, steep
- 85% agricultural
- Subsistence farming
- Vulnerable to climate
change (flood/drought)
- Food insecurity
- Improved Water
Management needed
IRAS: Increasing
resilience of agricultural
populations to climate
change by improving
water harvesting & water
management options
1st Project Objective: Estimating water supply availability for agricultural populations
Table 1. Primary Data Sources
Coordinate System: GCS_WGS_1984 UTM 48N with Datum: D_WGS_1984
Data Description Source Type Resolution
Elevation CGIAR-SRTM 3 sec data aggregated to 30 seconds CGIAR-SRTM Grid 3 seconds
Climate Monthly Precipitation, min/max Temperature WorldClim Grid 30 seconds
Boundaries Global Administrative Areas DIVA-GIS / GADM Vector Area
Population Population Density CIESEN grid 30 second
Land cover Land cover, data resampled to a 30 seconds grid GLC2000 Grid 30 seconds
PRIMARY ANALYSES
Watershed & Stream Network
Delineation
- Used CGIAR – SRTM 90m digital
elevation model (DEM)
- ArcGIS Spatial Analyst - Hydrology
tools
- Drainage analysis
- Recondition DEM
- Generate data on flow direction,
flow accumulation, streams,
stream segments and watersheds
- Develop vector representation of
catchments & drainage lines
- Area analysis of subwatersheds
(and target areas)
Parklai Subwatershed (purple):
grid value 203,840 (1651 km2)
Parklai Watershed (blue drainage network):
grid value 6,927,300 (56,111 km2)
𝐸𝑇𝑜 = 0.0135 𝐾𝑇 𝑅𝑎 ( (𝑇𝑚𝑎𝑥 − 𝑇𝑚𝑖𝑛 )) (𝑇𝑎𝑣𝑒 + 17.8)
Estimating ET from Temperature and Solar Radiation
(Hargreaves and Samani, 1982, 1985)
Where KT = 0.162 (interior) v. 0.19 coastal
Ra = solar radiation (monthly by latitude)
T in Celcius, monthly averages
Qin = P – ET – losses – Qout
Simplify to
Q = P – ET
for Ventiane and
generally for Laos 0.00
50.00
100.00
150.00
200.00
250.00
300.00
350.00
400.00
jan feb mar apr may jun july aug sep oct nov dec
Estimating Water Availability
- Used 1km (30 arc second) grids of climate
variables
- Hargreaves Equation to calculate ET
- Simplifying Assumptions Q = P - ET
- Key tools / processes
- Extract by mask (Laos & target areas)
- Raster Calculator
Raster Analysis of Temperature, Evapotranspiration, Precipitation
Key tools: Extract by Mask, Batch Processes, Model Builder, Raster Calculator
ET (Aug) = 𝑓 𝑇𝑚𝑎𝑥 , 𝑇𝑚𝑖𝑛 , 𝑅𝑎 , 𝐾𝑇
ET0 = 0.0135(KT)(Ra)(TD)1/2(TC+17.8)
Evapotranspiration
𝑇𝑚𝑎𝑥
𝑇𝑚𝑖𝑛
= –
Water Availability: Q(8) = Ppt(8) – ET(8)
Ppt(8)
ET(8)
Water Supply Index Q (August) :
Q ( P – ET ) / Population
= Water available per person
(browns indicate greater deficit)
–
Next: Agricultural Water Index:
Water / Agricultural Output
Target District Precipitation
Xayabouri Savannakhet
Annual average:
1678 mm
Annual average:
1636 mm
Comparison of weather station data with precipitation grids
Table 1. Xayabouri Monthly Precipitation 1971-2011 and 1950-2000 (mm)
GOOD
CORRELATION! ~ 10% annual average
~ better site specific data (if raingauge in different area)
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Sum
Station
Data 10 16 46 116 170 163 208 244 231 97 24 11 1333
Station
Max 104 108 219 316 342 509 350 427 530 282 51 46 3282
Xayabouri – Grid average in target districts 5135 km2 16 grids
Remote
Data 13 4 107 138 228 195 259 257 287 116 53 20 1678
Station
Max 21 45 168 285 418 330 331 307 771 285 96 27 3084
0
50
100
150
200
250
300
350
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Pre
cip
itation (
mm
)
Xayabouri Precipitation
Station Data
Remote Data
0
100
200
300
400
500
600
700
800
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Pre
cip
itation (
mm
)
Xayabouri Precipitation Max
Station Max
Station Max
Comparison of weather station data with precipitation grids
Table 2. Savannakhet Monthly Precipitation 1971-2011 and 1950-2000 (mm)
GOOD
CORRELATION! ~ 20% of annual average
~ greater remotely sensed
rainy season averages
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec sum
Station
Data 3 18 36 81 186 251 243 338 218 88 8 3 1473
Station
Max 34 48 80 72 106 188 118 139 185 101 38 26 1135
Savannakhet – Grid ave. in target districts 2211 km2 6 grids
Remote
Data 7 15 47 80 199 246 328 340 294 66 6 10 1636
Remote
Max 12 21 64 87 217 296 408 419 314 70 9 18 1935
0
50
100
150
200
250
300
350
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Pre
cip
itation (
mm
)
Savannakhet Precipitation
Station Data
Remote Data
0
50
100
150
200
250
300
350
400
450
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Pre
cip
itation (
mm
)
Savannakhet Precipitation Max
Station Max
Remote Max
Site Specific information needed
to more accurately estimate water
demand and deficits
Improvements Needed:
- Higher resolution DEM
- Agricultural Demands & Output
- Soil and Crop Data (better ET)
- Actual rainfall & temperature
Conclusion
Water availability can be
estimated from remotely
sensed products
GIS hydrological analysis
useful to estimate drainage
and watershed area
Precipitation grids provide
valuable monthly data for
water harvesting plans
Water Harvesting Technologies
Jeanny Wang Miles
Freshwater is scarce
Less than 0.01% of world’s freshwater surface water in lakes, rivers and wetlands
Water Harvesting: Intercept Precipitation or Surface Flow
Sustainable Water Harvesting
What makes it Sustainable?
• Applicable to varying situations
• Inexpensive
• Easily installed / maintained
• Desired by local population
Petrolina, Brazil http://www.ircsa.org/factsheets/lowincome.htm
Figure 3: Rock / River / Weir
Figure 2: Ground catchment system
Figure 1: Schematic of a typical
rooftop catchment system
Three Types of Water
Harvesting Systems
(Source: UNEP IETC, 1998)
Rooftop Catchment •Collect water in gutter
•Filter out debris, dirty initial
burst of rainwater
•Store in covered container
•Optional: pumps to
distribute water
Roofing Material Influences
Water Quality
Roofing Material Potential Contaminants
Asphalt Shingles
Mold, algae, bacteria, dust, soot,
moss, petroleum compounds,
gravel grit
Aluminum Aluminum
Galvanized metal Lead, cadmium, zinc
Sheet metal Lead
Tar shingles Copper
Terra cotta Mold, algae, bacteria, moss
Wood Mold, algae, bacteria, moss,
wood preservatives
Roof to Gutter to Storage Different features
• Filter or Sedimentation Tank
•Underground storage
•Pump
Wire mesh
concrete
Depending on what is locally available and affordable:
•Plastic tanks
•Ceramic jugs
•Concrete structures
Precast concrete
Storage Tanks
Comparison of Tank Materials
Ferro-concrete available locally, durable, inexpensive
Rainwater Storage Jars
Quality drinking water
100 to 3,000 litres
Equipped with lid, faucet, and drain
Inexpensive (<$60)
Enough for six-person household during dry season
Lao producers of 1000 liter jars in target villages (500,000 Kip)
Well ring tanks an option (50,000 Kip / D=.8m,.5m) x 4
1.2 m Well Ring Tank with Spigot
2000 liter concrete “jumbo” jar
• Need solid lid (reduce mosquitos and algae)
• Spigot or tap (10-30 cm above tank floor)
• Best on foundation of brick or cement
Concrete Jars
Cost of Jars and Well Ring Tanks
No.
needed Unit Unit size
(D, m) Height
(m) Units
Needed V
(liters) Unit Price (Kip/Baht)
Total Price (Kip)
Unit $ (USD)
Total $ (USD) note
Jars - ferrocement
50 liter jar 80 50 50,000 $ 6 $ 500 S-1
1000 Liter Jar Tank 4 1000 500,000
500,000 $ 63 $ 250 X-1 2000 Liter Thai
"Ong" 2 2000 800-1300 $ 45 $ 90 T-1
Cylindrical Tanks
Well Ring Tank with ~ $55 construction
cost per well
4 m 0.8 0.5 4 1000 50,000 $ 54 $ 272 X-2
3 m 1 1 2 2356 80,000
160,000 $ 60 $ 234
Plus two spigots ($6) and one lid ($15) per tank, plus cement, sand, spigots,
lid, foundation and labor costs, esp. for well-ring construction; total of 4000
liter capacity: approx. $65 jar, $56-60 well-rings (D .8-1m x 0.5-1, height)
• Gutter, hangers, downspout, pvc pipe, roof wash
• First Flush/Roof Washer: with gutter wedge or leaf screen
Conveyance System
Gutter Wedge Leaf Screen
“First Flush” allows first rains from roof
which are laden with dirt, debris and other
contaminants to be flushed out of the
system, before rainwater is collected.
Leaf Screen keeps large
debris out of tank
Typical Standpipe First Flush
“First Flush” Allows first rains to wash away dirt
and debris before collecting water
Example of Standpipe Roof Washer
How much water can you collect?
Collection = Annual Rainfall x Roof Area
In practice, achieve 70-80% of this due to:
– Evaporation
– Overflow
– Drainage system expelling dirty water at
beginning of rainfall
http://www.unep.or.jp/ietc/Publications/TechPublications/TechPub-
8e/rainwater1.asp
Design of Tank Size
Catchment Area x Average Rainfall x 75%
Vangthoum Elementary (42 x 8 = 336 m2)
Annual: 1678 mm x 336 m2 x 75% = 422 m3
May ave: 228 mm x 336 m2 x 75% = 57 m3
June ave: 195 mm x 336 m2 x 75% = 49 m3
May 80 per 0.7 m3/mo or 24 liters per/day
June 80 per 0.6 m3/mo or 20.5 liters per/day
Consider Daily Demand and Storage capacity:
choose four (1000 liter tanks)
Date Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec ave
Total 326 450 1072 2209 2618 3097 3414 3914 3809 1838 608 335 1974
Mean 11 15 36 74 87 103 114 130 127 61 20 11 790
Maxi 104 108 219 316 342 509 350 427 530 282 51 46 3282
Average of grids in target districts - Xayabouri 5135 km2 16 grids
Date Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec sum
Mean 13 4 107 138 228 195 259 257 287 116 53 20 1678
Sum 91 195 641 1516 3190 2928 4142 4118 4020 1511 372 121 22845
Maxi 21 45 168 285 418 330 331 307 771 285 96 27 3084
You Try: Catchment Area x Average Rainfall x 75%
Roof Area: 40 x 10 =
Rainfall (1 month) =
Collection Volume (m3) =
Efficiency (75%) =
Liters / person / day =
80 people (liter/per/day) =
Date Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec ave
Total 326 450 1072 2209 2618 3097 3414 3914 3809 1838 608 335 1974
Mean 11 15 36 74 87 103 114 130 127 61 20 11 790
Maxi 104 108 219 316 342 509 350 427 530 282 51 46 3282
Average of grids in target districts - Xayabouri 5135 km2 16 grids
Date Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec sum
Mean 13 4 107 138 228 195 259 257 287 116 53 20 1678
Sum 91 195 641 1516 3190 2928 4142 4118 4020 1511 372 121 22845
Maxi 21 45 168 285 418 330 331 307 771 285 96 27 3084
400 m2
200 mm (0.2 m)
80 m3
60 m3
2 m3 (2000 liters)
25 liters/ person/day
choose four (1000 liter tanks)
•Increase runoff to catchment tank by:
•Cemented earth, plastic sheets
•Compacted and smoothed soil
•Changing vegetation
•Store in tanks or dams
Land Surface Catchments
UNEP IETC, 1998
Ground Catchment
• Store rainfall & runoff in ditches, ponds, and
reservoirs for use in dry season
• Ponds with round edges better than square
• Gradual slopes for better access (people/animals)
• Maintain riparian and wetland vegetation
• For groundwater recharge, slow runoff, infiltration
• Use bentonite to minimize leaking
• Multi-purpose ponds, aquaculture
• Develop springs wisely
• Appropriate crop choices
Excavation Costs
Calculate Excavation Volumes
Better: Ponds with round edges not square; Gentle slopes on banks with vegetation
Calculation of Volume
(excavation amounts) width length depth V (m3)
Rectangular pond = W L D m3 20 30 2 1200
V (ovoid) = 4/3 pi W/2 L/2 D m3 20 30 3 942.5
V (ovoid) = 4/3 pi W/2 L/2 D m3 20 30 4 2513
V (spheroid) = 1/6 pi W L D D = 30 30 30 15 7069
Excavation unit width length depth V (m3) Kip Unit $ Total
USD
Contract excavation cost 3,000,000 $375
Contract excavation cost 20 20 2 800 5,000,000 $625
laborer - general 40 5 per-day 50,000 $ 6 $1,250
laborer - construction 40 5 per-day 70,000 $ 9 $1,750
Excavator cost /m3 m3 20 20 2 800 50,000 $ 6 $5,000
Excavator cost /m3 m3 20 20 2 800 80,000 $ 10 $8,000
Agro-Ecology System
• Efficient
• Multi-purpose
• Fish and farming system
• Ponds with round edges
• Gradual slopes
• Maintain trees and
wetland vegetation
• Maintain water supply
• Sustainable
(VITA, 1976)
Livestock / Aquaculture / Vegetables
• Livestock:
Watering troughs
• Floating
Aquaculture with
herb gardens
Micro-dams to recharge groundwater
•“Microdams” and trenches dug
to slow runoff of stormwater from
mountains
•More water percolates into soil,
recharging underground aquifers
•Well access to groundwater
•Low evaporation losses
•Prevents erosion
Groundwater pumping Energy and quality considerations
http://water.columbia.edu/research-projects/ethiopia/
http://blogs.ei.columbia.edu/2009/02/02/low-cost-water-management-
in-ethiopia/
Koraro, Ethiopia
Paklai – B. Vangthoum, B. Takdaet Phiang – B. Nasong, B. Kang
Xayabouri Site Visits
Paklai – drought region, little irrigation Phiang – domestic use from irrigation canals
Namlai Weir and Canal
Figure 6. Namlai Weir near Vangthoum Village Figure 7. Tatkai Canal fed by the Namlai River
Possible maintenance assistance with existing canal
(need to determine baseline and improvement)
Rainwater harvesting system at Vangthoum Primary in Paklai, Xayabouri
• Vangthoum Primary School
• 72 students and 5 teachers
• River 1km away (drinking water
from home, need water)
• Lateral roof area: 42 x 8 m2
• Height: 2.5 m at gutter
School Rooftop
Harvesting System
Rooftop size x Annual Rainfall
- 42 x 8 = 336 m2
- 1428 mm => 360 m3
Demand:
- 78 students, 5 teachers
- School in session Sep-May
Two jumbo jars in series
- $ 65 per tank
- $ 400 conveyance system and
accessories
- $ 875 for school system
First Flush System
Overflow to garden and recharge
(option) Back-up Borehole $400
Est. Material Costs for Vangthoum Rooftop Harvesting System
No. Unit Unit size
(D, m)
Height
(m)
Units Neede
d
V (liters
)
Unit Price
(Kip/Baht)
Total Price (Kip)
Unit $ (USD)
Total $ (USD)
note
Jars - ferrocement
1000 Liter Jar Tank 4 1000 500,000
2,000,00
0 $ 63 $ 250 X-1
Well Ring Tank 4 m 0.8 0.5 4 1005 $ 100 $ 400 X-2
Well Ring Tank 2 m 1 1 3 2356 $ 90 $ 180 X-2
Cover 1 $ 15
Total for four (1000 liter) jar tanks $ 265
Half Round Gutter (50cm) m 8 42 92 180 $ 6 $ 552 X-4
Hangers 13.14286 ea 14 80 $ 3 $ 37
Outlets & End Caps 1 ea 1 $ 5 $ 5
Y-split 2 ea 2 3000.0 $ 5 $ 10
First flush (pipe) 0.5 m 0.5 $ 5 $ 3
Spigot 4 ea 4 12000
48,000 $ 6 $ 24 V-2
PVC Piping 12 m 4 3 20000
60,000 $ 8 $ 23 V-2
PVC corners 6 ea 6 3000
18,000 $ 2 $ 14 V-2
Wire Mesh 1 m2 1 $ 11 V-2
Cloth weave 1 m 2 1 2 8000
16,000 $ 2 $ 4 V-2
Chlorine Tablets 2 kg 2 $ 20 $ 20
Total for conveyance and accessories (not inc. tank) $ 718
Total for 4000 L System (4 parallel tanks)
Jumbo Jars (1000 l) $ 968
Savannakhet Site Visits
Outhomphone: B. Nakaseng, B. Nakasot
Arid with inadequate storage Champhone: B. Phiaka, B. Kengpun
Villages in the river floodplain flood up to 1m
Hazards of River Weirs for Irrigation
- Improper sizing (inadequate flows)
- Erosion of banks
- Loss of riparian habitat
- Degrades stream channel /habitat
Huai Kao Weir (Outhomphone) completed in Oct. 2012
Vegetable Growing and Making Charcoal
can be profitable
Ms. Van ~ 2M kip profit from 300 m2 garden
Ideas for Xayabouri 1. Rooftop Rainwater Harvesting System in at least two
primary schools per district (+Vangthoum & Nasom).
2. Drill bore holes (wells) in Takdaet and Vangthoum
elementary for supplemental water supply.
3. Offer jumbo jars or well-ring tanks of 1-3 m3 size at
community sites ( hospitals and temples).
4. Promote agroforestry or planting of economic trees, or
other vegetation to maintain soil and moisture.
5. Encourage ecological design of non-stream
associated water supply – and multi-purpose ponds
6. Planning and design assistance to determine baseline
of water delivery system before improvements made.
7. Then possible installation of gate and sediment basin
at Nascing Weir or minor canal improvements.
Ideas for Savannakhet 1. School roof harvesting systems in two schools / district
2. Offer 1-2 m3 tanks (concrete or jumbo jar) for households:
3. Assist with process change of local manufacture from 50 liter
to 1000 liter jars with valves (B. Nongkhoun in Champhone).
4. Design and produce jar/tank covers
5. Encourage greenhouses and revegatation in Outhomphone
6. Offer and site livestock watering troughs
7. Encourage off-farm activities (black-smithing in
Outhomphone: B. Na Huakhua, B. NakaSot)
8. Encourage off farm activities (mat weaving in Champhone: B.
Kengpun; lead bird watching tours at the Bak or Ramsar site)
9. Introduce floating aquaculture ponds /herb gardens (Kengpun)
Priority Recommendations 1. School Water Harvest Systems in 2-3 schools
in each District in 2013
2. Back-Up Bore Holes in a few locales like Paklai
and Outhomphone; test groundwater quality
3. Non-stream affiliated multi-purpose ponds
4. Off-Farm Activities - Ecotourism in Champhone
5. Climate Change & Water Management training
and data-sharing through GIS/ Spatial Planning
6. Other Water Management links to CCTAMs
Climate Change Adaptations Increase in Temperature and Weather extremes
(hotter dry season, wetter wet season, more storms)
Increase in Unpredictability (more floods & droughts)
Adaptations: increased water harvesting, water
storage, efficient distribution
Adjust crop, tree, fish or livestock raising practices
Alternate livelihoods requiring less water
Needs knowledge of baseline conditions
Needs Tangible Benefits and links to water
management and climate change adaptation
What do you envision?
