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. 2014 Jun 28;43(8):1093–1111. doi: 10.1007/s13280-014-0538-3

Table 3.

Context scenarios and input data for UVQ modeling

Context scenario parameters Standard 2015 Standard 2050 Population growthb Climate changeb Water demandb Confidence
High Low High Low Increased Decreased
Populationa 62 055 150 872 181 047 120 698 150 872 150 872 150 872 150 872 Low
People/householda 4.8 6 7.2 4.8 6 6 6 6 High
Water demand (l/p/d)a 208 208 208 208 208 208 249 166 Medium
Precipitation (mm/yr)a 2066 2066 2066 2066 2129 2087 2066 2066 Medium
Evaporationa 1860 1860 1860 1860 1970 1970 1860 1860 Low
Infrastructure alternatives Units A-2015 A-2050 B-2050 C-2050 D-2050 E-2050 F- and G- 2050 Confidence
Water demandL1
 Kitchen L/p/d 39 39 39 39 39 39 See below Medium
 Bathroom L/p/d 86 86 86 86 86 86 Medium
 Toilet L/p/d 47 47 47 47 7L1a 47 Medium
 Laundry L/p/d 36 36 36 36 36 36 Medium
Rainwater tank m3 0 0 0 0 2 2 High
TN removal
 Existing homes % 10L2 10L2 30L3 30L3 30L3 30L3 Medium
 New homes % N/A 15L2 30L3 30L3 79L5 84L6 Medium
 Centralized WWTP % N/A N/A N/A 75L4 N/A N/A Medium
TP removal
 Existing homes % 10L2 10L2 35L3 35L3 35L3 35L3 Medium
 New homes % N/A 15L2 35L3 35L3 70L5 97L6 Medium
 Centralized WWTP % N/A N/A N/A 80L4 N/A N/A Medium
Cluster specific parameters Units Socio demographic context
Alternative F-2050 and (G-2050) CBD4 High4 Medium4 Low4 Confidence
Water demand
 Kitchen L/p/d 39 49 39 20 Medium
 Bathroom L/p/d 86 96 86 43 Medium
 Toilet L/p/d 47 57 47 23 Medium
 Laundry L/p/d 36 46 36 18 Medium
Rain tanks
 New dwellings KL 2 2 2 2 High
TN removal
 Existing homes (G) % 75L4 (30L3) 30L3 30L3 30L3 Medium
 New homes (G) % 75L4 (30L3) 84L6 52.5L7 79L8 Medium
TP removal
 Existing homes (G) % 80L4 (35L3) 35L3 35L3 35L3 Medium
 New homes (G) % 80L4 (35L3) 97L6 57.5L7 70L8 Medium
Cluster specific parameters Units Cluster density (A-2015) Cluster density (A-2050–F-2050)
CBD Medium Low CBD High Medium Low Confidence
Average block sizeb m2 1314 600 1092 450–800 180–250 400–600 600–800 High
Average roof sizeb m2 907 250 320 200–400 150 150–200 150–200 High
Average paved areab m2 296 0 0 230–300 0 0 0 High
Average garden sizeb m2 111 350 772 20–200 30–100 250 450–650 High
Road area (% of cluster area)b % 9–11 7.0–9.0 4.0–5.5 9–11 8–10 7.5–8.5 5.0–6.0 Medium
Constant parameters Units Confidence Calibration values Confidence
Nutrients to wastewaterL9 Roof area initial lossL10 0.5 Medium
 Kitchen—N g/p/d 0.3 Medium Effective roof areab 50–85 % Medium
 Kitchen—P g/p/d 0.1 Medium Paved area initial lossL10 0.1 Medium
 Bathroom—N g/p/d 0.35 Medium Effective paved areab 50–85 % Medium
 Bathroom—P g/p/d 0.2 Medium Road surface initial lossL10 0.2 Medium
 Toilet—N g/p/d 8.2 Medium Effective road surface areab 50–85 % Medium
 Toilet—P g/p/d 1.2 Medium Contaminant soil store removalL10 0 Low
 Laundry—N g/p/d 0.28 Medium Wastewater infiltration indexL10 0.001 Low
 Laundry—P g/p/d 0.2 Medium Garden irrigationa 0 High
Stormwater qualityb
 TN mg/L 1.3 High Public open space irrigationa 0 High
 TP mg/L 0.34 High

aData collected through field measurement throughout entire study area

bData collected through field measurements within study from a limited number of sites and extrapolated to entire study area

L Literature. Input parameters sourced from the local or international literature and assumed to be accurate and acceptable values for application in Port Vila

L1 The ratio of indoor water use is based on the literature (Huang et al. 2007)

L1a Allows for 7L/p/d for feces flush, with urine diverting toilets (Huang et al. 2007)

L2 Nutrient removal in poor performing septic systems (Montangero and Belevi 2008) this reflects known condition of majority of septic systems in Port Vila (ADB 1998)

L3 Best possible nutrient removal efficiency of septic systems expected in Port Vila (von Sperling et al. 2005)

L4 Proposed wastewater treatment plant nutrient removal efficiency (ADB 2010)

L5 Allows for 80 % successful urine diversion and nutrient collection. Then standard nutrient removal for feces/misdirected urine in septic system

L6 Total removal efficiency after septic treatment then onsite effluent treatment (Chang et al. 2011) suitable in developing, tropical context (Parkinson and Taylor 2003)

L7 Allows for 50 % connection to WWTP and 50 % septic systems (ADB 2010)

L8 Allows for 80 % successful urine diversion and nutrient collection. Then standard nutrient removal for feces/misdirected urine in septic system

L9 Nutrients per person per day to excreta are diet dependent with no local data. Parameter values based on Huang et al. (2007)

L10 These stormwater and wastewater parameter values based on Mitchell and Diaper (2005b)

L11 CBD—2 clusters; high density—2 clusters; medium density—2 clusters; low density—3 clusters