Table 3 Water resilience determining parameters and their sub-classes with area and weights
From: Water resilience mapping of Chennai, India using analytical hierarchy process
S. No. | Parameters | Class | Water resilience | Score | Area (km2) | Percentage (%) | Source | Weight |
|---|---|---|---|---|---|---|---|---|
1 | Soil depth (cm) | Extremely shallow (< 10) | Very low | 1 | 252.119 | 59.18 | India Water Resources Information System | 0.167 |
Moderately shallow (> 50) | Moderate | 5 | 173.881 | 40.82 | ||||
2 | Geomorphology | Coastal plain | Very low | 1 | 119.28 | 28.00 | Geological Survey of India | 0.149 |
Deltaic plain | High | 7 | 225.78 | 53.00 | ||||
Flood plain | Very low | 1 | 12.78 | 3.00 | ||||
Pediment pediplain complex | Moderate | 5 | 68.16 | 16.00 | ||||
3 | Drainage density (km/km2) |  < 0.00236 | Very high | 9 | 99.388 | 23.33 | Based on DEM from SRTM | 0.125 |
0.00236–0.0072 | High | 7 | 127.863 | 30.01 | ||||
0.0072–0.0127 | Moderate | 5 | 110.933 | 26.04 | ||||
0.0127–0.0195 | Low | 3 | 72.059 | 16.92 | ||||
0.0195–0.043 | Very low | 1 | 15.757 | 3.70 | ||||
4 | Depth to water table (metres below ground level) | 4.45–6.03 | Very high | 9 | 44.625 | 10.48 | India Water Resources Information System | 0.108 |
6.04–6.92 | High | 7 | 76.715 | 18.01 | ||||
6.93–7.73 | Moderate | 5 | 92.535 | 21.72 | ||||
7.73–8.59 | Low | 3 | 162.091 | 38.05 | ||||
8.60–10.03 | Very low | 1 | 50.035 | 11.75 | ||||
5 | Flood inundation depth (feet above ground level) |  < 2 | Very high | 9 | 32.525 | 7.64 | Tamil Nadu State Disaster Management Authority | 0.094 |
2–3 | High | 7 | 125.521 | 29.47 | ||||
3–4 | Moderate | 5 | 130.275 | 30.58 | ||||
4–5 | Low | 3 | 102.470 | 24.05 | ||||
 > 5 | Very low | 1 | 35.210 | 8.27 | ||||
6 | Land use/Land cover | Settlements | Very low | 1 | 330.826 | 77.66 | Calculated from LANDSAT-8 OLI, USGS Earth Explorer | 0.073 |
Vegetation | Very high | 9 | 42.939 | 10.08 | ||||
Waterbodies | Very low | 1 | 31.751 | 7.45 | ||||
Scrubs & Bare soil | Moderate | 7 | 20.483 | 4.81 | ||||
7 | Rainfall (mm) |  < 1092 | Very low | 1 | 223.545 | 52.48 | India Water Resources Information System | 0.068 |
1092–1168 | Moderate | 5 | 72.061 | 16.92 | ||||
1168–1264 | High | 7 | 35.872 | 8.42 | ||||
1264–1323 | Low | 3 | 32.241 | 7.57 | ||||
1323–1417 | Very low | 1 | 62.280 | 14.62 | ||||
8 | Underground sewerage network coverage (%) |  < 20 | Very low | 1 | 47.712 | 11.20 | Based on Chennai Metro Water Supply and Sewerage Board reports and Survey | 0.055 |
20–40 | Low | 3 | 59.555 | 13.98 | ||||
40–60 | Moderate | 5 | 112.847 | 26.49 | ||||
60–80 | High | 7 | 57.766 | 13.56 | ||||
 > 80 | Very high | 9 | 148.120 | 34.77 | ||||
9 | Water supply network coverage (%) |  < 40 | Very low | 1 | 29.755 | 6.98 | Based on Chennai Metro Water Supply and Sewerage Board reports and Survey | 0.042 |
40–60 | Low | 3 | 146.578 | 34.41 | ||||
60–80 | Moderate | 5 | 79.148 | 18.58 | ||||
 > 80 | Very high | 9 | 170.518 | 40.03 | ||||
10 | Per capita water supply (lpcd) |  < 40 | Very low | 1 | 101.404 | 23.80 | Chennai Smart City Limited | 0.034 |
40–60 | Very low | 1 | 123.353 | 28.96 | ||||
60–90 | Low | 3 | 81.950 | 19.24 | ||||
90–120 | Moderate | 5 | 40.700 | 9.55 | ||||
 > 120 | High | 7 | 78.592 | 18.45 | ||||
11 | Distance from the water bodies and wetlands (m) |  < 500 | Very low | 1 | 141.540 | 33.23 |  | 0.025 |
500–1000 | Moderate | 5 | 208.210 | 48.88 | ||||
 > 1000 | High | 7 | 76.250 | 17.90 | ||||
12 | Population density (persons/km2) | 1000–5000 | Very high | 9 | 120.563 | 28.30 | Chennai Smart City Limited | 0.021 |
5000–10,000 | High | 7 | 65.425 | 15.36 | ||||
10,000–20,000 | Moderate | 5 | 81.009 | 19.02 | ||||
20,000–50,000 | Low | 3 | 128.203 | 30.09 | ||||
 > 50,000 | Very low | 1 | 30.801 | 7.23 | ||||
13 | Slope (%) | 0–3.35 | Very low | 1 | 152.04 | 35.69 | Based on DEM from SRTM | 0.0155 |
3.35–5.96 | Very low | 1 | 160.69 | 37.72 | ||||
5.96–10.06 | Low | 3 | 91.83 | 21.56 | ||||
10.06–20.12 | Moderate | 5 | 19.86 | 4.66 | ||||
20.12–95.04 | High | 7 | 1.57 | 0.37 | ||||
14 | NDVI | (-0.87)Â to (-0.63) | Very low | 1 | 122.42 | 28.74 | Calculated from LANDSAT-8 OLI, USGS Earth Explorer | 0.012 |
(-0.63) to (-0.59) | Very low | 1 | 114.83 | 26.96 | ||||
(-0.59) to (-0.54) | Low | 3 | 125.54 | 29.47 | ||||
(-0.54) to (-0.47) | Moderate | 5 | 52.38 | 12.30 | ||||
(-0.47) to (-0.43) | High | 7 | 10.83 | 2.54 | ||||
15 | NDWI | 0.47–0.55 | Very low | 1 | 65.45 | 15.36 | Calculated from LANDSAT-8 OLI, USGS Earth Explorer | 0.01 |
0.55–0.59 | Low | 3 | 106.77 | 25.06 | ||||
0.59–0.62 | Moderate | 5 | 142.80 | 33.52 | ||||
0.62–0.65 | High | 7 | 95.01 | 22.30 | ||||
0.65–0.86 | Very high | 9 | 15.98 | 3.75 |