Water Balance Study:Manoa Valley Sept 2 to Nov 4, 2016

Tineill Dudoit - Shellie Habel - Madi MiyamuraShintaro Russell - Kenui Topp

Mānoa Valley● Site Area: Mānoa Valley, (11,187,443 m^2 ) faces along the South-eastern steep

slopes of The Koʻolau mountain range

● Experiences almost daily rainfall

● Differing gradients of elevation, climate, land uses, crops and soil types,

including native forests, thick vegetation and dense shrub/tree areas

Purpose - Estimate Water availability for Mānoa Valley case study area

- Gather other groups inputs and outputs from Mānoa valley case study

- Compute and complete water balance using ArcGis, totaling various

meteorological processes, parameters and estimated rates of water inputs

and outputs that affected Mānoa Valley and Mānoas water budget in total

From Sept 2 - Nov 4, 2016

Estimate Total Outputs

-Change in soil moisture

- Distributed groundwater recharge

- Distributed evapotranspiration (Canopy and surface/soil Evaporation)

source:https://laulima.hawaii.edu/access/content/group/2c084cc1-8f08-442b-80e8-ed89faa22c33/book/chapter_7/balance.htmSource:http://climate.socialsciences.hawaii.edu/Courses/GEOG405/GEOG%20405%20Water%20Bala

nce.pptx.pdf

AW = Available WaterAWC = Available Water Content*Root DepthGWR = Groundwater

INPUT DATA REQUIREMENTS (DAILY, WEEKLY, OR MONTHLY INTERVAL)P RAINFALL

RO RUNOFF

IRR IRRIGATION

PE POTENTIAL EVAPOTRANSPIRATION

INPUT PARAMETERSAMC AVAILABLE SOIL MOISTURE CAPACITY (EQUIVALENT WATER DEPTH PER SOIL DEPTH)

AWC = AMC * ROOT

ROOT ROOT DEPTH

SINIT INITIAL SOIL MOISTURE CONTENT

CF CROP FACTOR (COEFFICIENT TO ADJUST PE)

OUTPUTSEND SOIL MOISTURE CONTENT SOIL.OUT

RCHG RECHARGE RCHG.OUT

E EVAPOTRANSPIRATION EVAP.OUT

Available Water Capacity

★ Available Water Capacity is the difference between field

capacity which is the maximum amount of water the soil can

hold and the wilting point where the plant can no longer

extract water from the soil

Source:http://soilquality.org.au/

Available Water Capacity

★ Is the water held between field capacity and the wilting point

★ Is the maximum amount of soil moisture available for the ET

process.

★ Can be expressed either as a ratio or in water depth units

Available Water Capacity

Source:http://www.extension.umn.edu

Changes in Soil Water. Field capacity minus wilting point is the amount of water available to plants

Soil Types

1. rRt = Rough Mountainous Land

2. rCl = Cinderland

3. rRk = Rock Land

4. LoC = Lolekaa Silty Clay, 8 to 15 percent slope

5. LoD = Lolekaa Silty Clay, 15 to 25 percent slope

6. LoE = Lolekaa Extremely Stony Clay, 3 to 35 percent slope

Soil Types

7. LoF = Lolekaa Silty Clay, 40 to 70 percent slope

8. TAE = Tantalus Silt Loam, 15 to 40 percent slope

9. TAF = Tantalus Silt Loam, 40 to 70 percent slope

10. TCC = Tantalus Silty Clay Loam, 15 to 40 percent slope

11. HnA = Hanalei Silty Clay, 0 to 2 percent slope

12. HnB = Hanalei Silty Clay, 2 to 6 percent slope

Soil Types

13. HoB = Hanalei Stony Clay, 2 to 6 percent slope

14. MIA = Makiki Stony clay Loam, 0 to 3 percent slope

15. LoB = Lolekaa Silty Clay, 3 to 8 percent slope

AWC Values for each Soil Type1. rRt = Rough Mountainous Land AWC = 0.135

2. LoF = Lolekaa Silty Clay, 40 to 70 percent slope AWC = 0.110

3. TAE = Tantalus Silt Loam, 15 to 40 percent slope AWC = 0.120

4. LoD = Lolekaa Silty Clay, 15 to 25 percent slope AWC = 0.110

5. TAF = Tantalus Silt Loam, 40 to 70 percent slope AWC = 0.120

6. HoB = Hanalei Stony Clay, 2 to 6 percent slope AWC = 0.170

7. LoC = Lolekaa Silty Clay, 8 to 15 percent slope AWC = 0.110

8. LoE = Lolekaa Silty Clay, 25 to 40 percent slope AWC = 0.110

9. rRk = Rock Land AWC = 0.140

10. HnA = Hanalei Silty Clay, 0 to 2 percent slope AWC = 0.170

11. rCl = Cinderland AWC = 0.030

12. TCC = Tantalus Silty Clay Loam, 15 to 40 percent slope AWC = 0.110

13. MIA=Makiki Stony Clay Loam, 0 to 3 percent slope AWC = 0.140

14. LoB=Lolekaa Silty Clay, 3 to 8 percent slope AWC = 0.110

15. HnB=Hanalei Silty Clay, 2 to 6 percent slope AWC = 0.170

Putting Together the Parameters★ Imported a shapefile from nrcs.usda.gov into ArcGIS

★ This geospatial file contains the different types

within our watershed

★ ArcGIS takes these soil types and splits them into

polygons and separates them into each grid cell

Putting Together the Parameters★ Divide the soil type area by the total area within

each cell to get the % soil type in each gridcell

★ AWC for each soil type can be found in the Soil

Survey of the State of Hawaii

★ Multiply the AWC to the % soil type(s) in each grid

cell

Putting Together the Parameters★ The AWC for each soil type in each grid cell is then

added together for a weighted average of AWC in

each grid cell

★ The values for weighted average of AWC in each

grid cell is used as a parameter in the Water Balance

Model

Putting Together the Parameters: geospatial files ✓ AMC

❏ Root Depth

❏ Crop Factor

Root DepthPer Square:

Root depth x % paved +

Root depth x % forest =

Weighted Average Root Depth

% AWC x weighted root depth =

Depth of water

Crop factor A correction factor for ET

→ land covers/crop that is not under “standard conditions”

→ excellent soil moisture, conditions etc.

(Crop factor x % paved) + (crop factor x %heavily forested) + (crop factor x %

forested) = Weighted

Irrigation

Used an Irrigation water balance file off of USGS

Blue = 0 ( NO irrigation)

Colored= 1 (Irrigation)

Modeled Soil Moisture vs Observed Soil Moisture

Total Precip (mm)

Total Potential Evap (mm)

Total Actual Evap (mm)

TotalRunoff (mm)

Total Recharge (mm)

Precipitation-Recharge Threshold

Precipitation-Recharge Threshold

Average TotalDepth Per Cell (mm)

Volume (m^3) Volume (gallons)

Precipitation 916 1087532 290 million

Evaporation 163 192967 51 million

Runoff 437 518564 137 million

Recharge 325 385639 102 million

Manoa Watershed Totals

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Giambelluca, T.W., X. Shuai, M.L. Barnes, R.J. Alliss, R.J. Longman, T. Miura, Q. Chen, A.G. Frazier, R.G. Mudd, L. Cuo, and A.D. Businger. 2014.

Evapotranspiration of Hawai‘i. Final report submitted to the U.S. Army Corps of Engineers—Honolulu District, and the Commission on Water

Resource Management, State of Hawai‘i.