Flood hazard mapping using GIS-based statistical model in vulnerable riparian regions of sub-tropical environment

Figures & data

Figure 1. Location map of the study area (a) India, (b) West Bengal, and (c) Malda district.

Table 1. Flood-affected areas of the Malda district based on DDMPM (2020-2021).

Sl. No.	Name of Blocks	Name of the G.P.	G.P wise Flood Prone Villages	Adjoining Rivers
1.	Harishchandrapur-II	Doulatnagar	Doulatnagar, Khidirpur and Mihahat	Mahananda and Fulhar
		Bhaluka	Hattichapa, Par Bhaluka
		Islampur	Basta, Bhajana, Chandpur, Chandipur Dakhin Bhakuria Imamnagar, Islampur, Khopakathi and Uttar Bhakuria
2.	Ratua-I	Debipur	Balupur, Debipur, Durgapur and Terashia	Fulhar, Koshi and Kalindri
		Mahanandatola	Badantola, Bajitpur, Bankutola, Dharmatola, Jagabandhutola, Janjalitola, Sambalpur and Sudamtola
		Bilaimari	Ajijtola, Dewanwala, Gangaramtola, Khasmahal, Nakkati, Nayabilaimari, Ramayanpur, and Ruhimari
		Kahala	Asutola, Haragobindapur, Kahala, Kalutola, Kamalpur, Narattampur and Suryapur
		Baharal	Baharal, Nimtalli, Sahapur Uttar and Sahapur Dakshin
3.	Manikchak	Gopalpur	Balutola, Elahitola (Part), Iswartola (Part), Kalitola, Kamaltipur, Nasutola (Part) and Sahabattola (Part)	Ganga and Fulhar
		Dharampur	Barabagan (Part), Sonapur and Wahedmara
		Manikchak	2No.Bridgepara, Chamatola. Darbaritola, Domhat, Jalalpur (part), Jotpatta, Madantola, Manikchak Ghat Bandh Para, Mankud, Narayanpur, Narayanpur Id Gaha Para, New Sonapur, Palpara, Rabidaspara, Ramnagar and Sibantola
		Dakshin Chandipur	Amintola, Bhabanitola, Bipintola, Bhabanathtola, Bhimtola, Bhojantola, Debutola, Durgaramtola, Duyani Char, Ganeshtola, Jaipaltola, Krishnatola, Lutihara, Mahendratola, Nabadiptola, Nayantola, Panchutola, Payaritola, Pulintola Bandh, Raghunathtola, Ratantola and Sukdevtola
		Hiranandapur	Anantalaltola, Bagedantola, Bagdukra, Baikunthatola Benutola Colony, Chabiltola, Debutola, Domontola, Gadai, Giridharotola, Gourangatola, Kalutontola, Lutihara, Mathurtola, Nanditola, Piyaritola and Rajkumartola.
		Nazirpur	Haripur (Part), Jitmanpur (Part), Laksikol (Part) and Laskarpur (Part)
4.	Kaliachak-II	Bangitola	Bintola, Chowdhutytola, Gosaihat, Jote Kostuty, Mahadevpur and Sadipur	Ganga and Fulhar
		Uttar Panchanandapur-I	Dolboxtola, Jinerditola, Laskaritola, Loharditola, Nasarattola, Paglaghat Bus Stand, Ramlaltola (part) and Sultantola
		Uttar Panchanandapur-II	Dhelfora, Jitnagar and Jugaltola
		Hamidpur	8 No. Spar Bandh, Chechrutola, Chumkitola, Etwaritola, Jatintola, Khatiakhana Char, Mathabhanga, Piaritola (East and West), Shibutola, Shripur colony, and Tofi
		Rajnagar	Bromottar and Nayagram Model
5.	Kaliachak-III	Birnagar-II	Asgarhajitola and Dinutola	Ganga and Fulhar
		Laxmipur	Ajimtola, Atartola, Bhangatol, Hajrattola, Jagantpur Mouza
		Krishnapur	Charsujapur, Kalitola, Mondai and Surenmandalpara
		Bakhrabad	Deonapur
		Kumbhira	Noornagar and Sabdalpur
		Pardeonapur-Sovapur	Dalpra, Golapman, Paranupnagar, Parlalpur and Shibpur

District Disaster Management Plan, Government of West Bengal, Office of the District Magistrate, Malda (2018, 2019–2020, 2020–2021) (http://wbdmd.gov.in/writereaddata/uploaded/DP/DPMalda57797.pdf).

Figure 2. Methodological flowchart of the flood risk assessment.

Figure 3. Flood susceptibility conditioning parameters of the Malda district: (a) elevation, (b) slope, (c) Topographical wetness index (TWI), (d) Topographical positioning index (TPI), (e) normalized difference vegetation index (NDVI), (f) modified normalized difference water index (MNDWI), (g) drainage density, (h) distance to river, (i) Stream power index (SPI), (j) modified fourier index (MFI) and (k) lithology.

Figure 4. Pearson Correlational Matrix among the different flood susceptibility parameters.

Figure 5. Flood vulnerability conditioning parameters of the Malda district: (a)total population, (b) population density, (c) land use land cover (LULC), (d) distance to flood shelter, (e) distance to hospital, (f) distance to road, (g) road density, (h) illiteracy rate and (i) employment rate.

Figure 6. Pearson Correlational Matrix among the different flood vulnerability parameters.

Table 2. Source and description of the parameters used in susceptibility and vulnerability zonation.

Parameters	Descriptions	Source
Elevation, Slope, TWI, TPI, SPI, STI, Drainage Density and Distance to River	Derived from ASTER DEM (30m*30m) and prepared the thematic layer using ArcGIS 10.4.1	United States of Geological Survey (USGS) Retrieved from: (https://earthexplorer.usgs.gov)
NDVI, MNDWI and LULC	Landsat-8 OLI/TIRS, (30m*30m)	United States of Geological Survey (USGS) Retrieved from: (https://earthexplorer.usgs.gov)
Rainfall Intensity using MFI	Gridded rainfall (0.25*0.25) NetCDF File	Indian Meteorological Department (IMD) Retrieved from: (http://www.imdpune.gov.in)
Lithology	Digital lithological map of the district	Geological Survey of India (GSI) Retrieved from: (http://bhukosh.gsi.gov.in/)
Total population, Population density, Illiteracy rate and Employment rate	Obtaining the village-level data from Census of India, 2011	Office of the Register General & Census Commissioner, India Retrieved from: (http://censusindia.gov.in/)
Distance to flood shelter	Adopting the data from DDMPM (2020-2021)	District Disaster Management Plan of Malda District, West Bengal (2020-2021), Retrieved from: (http://wbdmd.gov.in/writereaddata/uploaded/DP/DPMalda59094.pdf)
Distance to hospital, Distance to road, and Road density	Adopting the data from OpenStreetMap	OpenStreetMap Retrieved from: (www.openstreetmap.org)

Table 3. Saaty’s scale of relative importance.

Numerical Value	Definition
1	Equal importance
2	Equal to moderate importance
3	Moderate importance
4	Moderate to strong importance
5	Strong importance
6	Strong to very strong importance
7	Very strong importance
8	Very to extremely strong importance
9	Extreme importance
1/1 to 1/9	Reciprocal values

Table 4. Random index (RI) to check the consistency ratio for different matrices (Saaty and Vargas 1991).

1	2	3	4	5	6	7	8	9	10	11	12	13	14	15
0	0	0.58	0.9	1.12	1.24	1.32	1.41	1.45	1.49	1.51	1.48	1.56	1.57	1.59

Table 5. Multicollinearity Statistics of flood susceptibility and vulnerability parameters.

SP	E	S	TWI	TPI	NDVI	MNDWI	DD	DR	SPI	STI	MFI	L
Tolerance	0.579	0.781	0.555	0.721	0.790	0.754	0.540	0.538	0.161	0.151	0.991	0.945
VIF	1.727	1.280	1.802	1.386	1.266	1.327	1.853	1.858	6.216	6.626	1.009	1.058
SP: Susceptibility Parameters, E: Elevation, S: Slope, TWI: Topographic Wetness Index, TPI: Topographic Position Index, NDVI: Normalized Difference Vegetation Index, MNDWI: Modified Normalized Difference Water Index, DD: Drainage Density, DR: Distance to River, SPI: Stream Power Index, STI: Sediment Transport Index, MFI: Modified Fourier Index, L: Lithology.
VP	TP	FP	PD	CD	LR	ILR	DFS	DH	LULC	ER	RD	DTR
Tolerance	0.310	0.003	0.111	0.004	0.559	0.517	0.803	0.887	0.941	0.409	0.501	0.594
VIF	3.220	286.659	8.989	229.811	1.790	1.933	1.246	1.127	1.063	2.448	1.997	1.683

VP: Vulnerability Parameters, TP: Total Population, FP: Female Population, CD: Child Population, LR: Literacy Rate, ILR: Illiteracy Rate, DFS: Distance to Flood Shelter, DH: Distance to Hospital, LULC: Land Use Land Cover, ER: Employment Rate, RD: Road Density, DTR: Distance to Road.

Table 6. Multi-collinearity diagnosis of flood susceptibility and vulnerability parameters.

Dimension	Susceptibility		Vulnerability
	Eigenvalue	Condition Index	Eigenvalue	Condition Index
1	6.181	1.000	7.556	1.000
2	1.885	1.811	2.547	1.722
3	1.023	2.458	0.756	3.162
4	0.886	2.641	0.305	4.978
5	0.822	2.743	0.257	5.426
6	0.479	3.591	0.198	6.177
7	0.301	4.531	0.138	7.395
8	0.152	6.370	0.100	8.695
9	0.101	7.830	0.090	9.182
10	0.093	8.173	0.036	14.511
11	0.060	10.130	0.016	21.618
12	0.016	19.966	0.002	64.907

Figure 7. (a) Flood susceptibility zonation, (b) flood vulnerability zonation, and (c) flood risk zonation map of Malda district.

Table 7. AHP Table for flood susceptibility Zone analysis.

Parameters	AHP Weight	Reclass	Class Range	Flood Level	Area in Sq. Km	Area in %	Rating
Elevation	0.267	1	5 − 20	Very High	719.75	19.63	0.416
		2	21 − 26	High	1512.19	41.25	0.262
		3	27 − 32	Medium	874.30	23.85	0.161
		4	33 − 39	Low	425.72	11.61	0.099
		5	40 − 80	Very Low	134.01	3.66	0.062
Slope	0.192	1	0.00 − 2.09	Very High	1054.44	28.76	0.444
		2	2.10 − 4.05	High	1211.89	33.06	0.262
		3	4.06 − 6.42	Medium	901.48	24.59	0.153
		4	6.43 − 9.64	Low	399.86	10.91	0.089
		5	9.65 − 35.61	Very Low	98.30	2.68	0.053
TWI	0.087	1	3.76 − 8.03	Very Low	1234.81	33.68	0.053
		2	8.04 − 11.10	Low	705.11	19.23	0.089
		3	11.11 − 13.66	Medium	842.15	22.97	0.153
		4	13.67 − 16.73	High	726.90	19.83	0.262
		5	16.74 − 25.52	Very High	157.00	4.28	0.444
TPI	0.015	1	−4.72 − 1.50	Very High	983.01	26.74	0.489
		2	−1.49 − 0.00	High	696.84	18.96	0.261
		3	0.00 − 0.01	Medium	327.53	8.91	0.138
		4	0.02 − 2.50	Low	1610.11	43.81	0.073
		5	2.51 − 5.29	Very Low	58.09	1.58	0.038
NDVI	0.028	1	−0.12 − 0	Very High	663.80	18.11	0.416
		2	0.01 − 0.11	High	1473.97	40.21	0.262
		3	0.12 − 0.16	Medium	907.42	24.75	0.161
		4	0.17 − 0.23	Low	436.94	11.92	0.099
		5	0.24 − 0.40	Very Low	684.50	18.67	0.062
MNDWI	0.063	1	−0.35 − 0.11	Very Low	1211.45	33.05	0.056
		2	−0.10 − 0.04	Low	1386.03	37.81	0.096
		3	−0.03 − 0.04	Medium	185.29	5.05	0.157
		4	0.05 − 0.17	High	198.69	5.42	0.257
		5	0.18 − 0.37	Very High	894.33	24.40	0.434
Drainage Density	0.123	1	0.00 − 0.14	Very Low	727.86	19.85	0.050
		2	0.15 − 0.27	Low	894.33	24.40	0.088
		3	0.28 − 0.40	Medium	955.64	26.07	0.151
		4	0.41 − 0.55	High	729.40	19.90	0.259
		5	0.56 − 0.87	Very High	358.70	9.78	0.454
Distance from the River	0.122	1	0.00 − 436.58	Very High	1015.75	27.71	0.503
		2	436.59 − 900.44	High	950.41	25.93	0.260
		3	900.45 − 1,391.59	Medium	804.43	21.94	0.134
		4	1,391.60 − 1,964.59	Low	622.27	16.97	0.068
		5	1,964.60 − 3,478.97	Very Low	273.07	7.45	0.035
SPI	0.015	1	0.00 − 0.01	Very High	1340.15	36.56	0.503
		2	0.02 − 99.65	High	2155.67	58.80	0.260
		3	99.66 − 193.30	Medium	51.23	1.40	0.134
		4	193.31 − 498.25	Low	47.11	1.29	0.068
		5	498.26 − 2,052,755.38	Very Low	71.81	1.96	0.035
STI	0.015	1	0.00 − 0.01	Very High	2156.88	58.84	0.503
		2	0.02 − 3.69	High	1143.47	31.19	0.260
		3	3.70 − 11.07	Medium	268.96	7.34	0.134
		4	11.08 − 22.14	Low	49.92	1.36	0.068
		5	22.15 − 8,420.94	Very Low	46.74	1.28	0.035
MFI	0.044	1	239.61 − 252.35	Very Low	70.52	1.92	0.053
		2	252.36 − 260.71	Low	1003.81	27.38	0.089
		3	260.72 − 269.27	Medium	1308.32	35.69	0.153
		4	269.28 − 278.03	High	882.20	24.06	0.262
		5	278.04 − 290.37	Very High	401.08	10.94	0.444
Lithology	0.028	1	CLAY WITH SAND, SILT, AND IRON NODULE	Low	492.70	13.44	0.070
		2	FEEBLY OXIDIZED SAND, SILT, AND CLAY	Very High	59.87	1.63	0.501
		3	SAND, SILT & GRAVEL	Medium	134.54	3.67	0.159
		4	SAND, SILT, AND CLAY	Very Low	2648.23	72.24	0.035
		5	SAND, SILT, CLAY WITH CALCAREOUS CONCRETIONS	High	330.59	9.02	0.235

Table 8. Consistency check of aggregated for flood hazard in the Malda district.

Lambda Max	N	Consistency Index	Consistency Ratio
13.26	12	0.115	0.077

Table 9. AHP Table for flood vulnerability Zone analysis.

Parameters	AHP Weight	Reclass	Class Range	Flood Level	Area in Sq. Km	Area in %	Rating
Total Population	0.235	1	0	Very Low	225.94	6.16	0.044
		2	1 − 2,000	Low	1612.14	43.98	0.084
		3	2001 − 4000	Moderate	682.51	18.89	0.148
		4	4,001 − 10,000	High	851.43	23.23	0.256
		5	>10000	Very High	283.93	7.75	0.467
Population Density	0.235	1	0	Very Low	225.94	6.16	0.044
		2	1 − 500	Low	1325.64	36.16	0.084
		3	501 − 1,000	Moderate	1068.57	29.15	0.148
		4	1.001 − 2.000	High	776.45	21.18	0.256
		5	>2000	Very High	269.36	7.35	0.467
Illiteracy Rate	0.038	1	0	Very Low	227.44	6.21	0.035
		2	1 − 20	Low	20.32	0.55	0.068
		3	21 − 40	Moderate	467.70	12.76	0.134
		4	41 − 60	High	2262.73	61.75	0.260
		5	61 − 100	Very High	686.11	18.72	0.503
Distance to Flood Shelter	0.096	1	0 − 1,000	Very Low	48.08	1.31	0.048
		2	1001 − 2000	Low	110.45	3.01	0.085
		3	2,001 − 3,000	Moderate	121.88	3.32	0.148
		4	3,001 − 5,000	High	234.64	6.40	0.234
		5	5,001 − 55,738	Very High	3150.90	85.95	0.485
Distance to Hospital	0.096	1	0 − 2000	Very Low	645.71	17.61	0.049
		2	2,001 − 3,000	Low	683.52	18.65	0.082
		3	3,001 − 5,000	Moderate	1347.53	36.76	0.149
		4	5001 − 10000	High	973.04	26.54	0.267
		5	10,001 − 12,667	Very High	16.15	0.44	0.454
LULC	0.153	1	Waterbody	Very Low	285.28	7.78	0.035
		2	Vegetation Cover	Moderate	501.44	13.68	0.134
		3	Agricultural Field	High	2167.42	59.12	0.260
		4	Bare Ground	Low	68.70	1.87	0.068
		5	Built-up Area	Very High	643.10	17.54	0.503
Employment Rate	0.027	1	0	Very High	222.81	6.08	0.467
		2	1 − 40	High	1959.26	53.44	0.256
		3	41 − 50	Moderate	1001.20	27.31	0.148
		4	51 − 60	Low	337.81	9.21	0.084
		5	61 − 100	Very Low	141.24	3.85	0.044
Road Density	0.060	1	0.00 − 0.21	Very High	1371.73	37.42	0.426
		2	0.22 − 0.64	High	1484.77	40.50	0.259
		3	0.65 − 1.19	Moderate	538.31	14.68	0.159
		4	1.20 − 2.93	Low	251.75	6.87	0.097
		5	2.94 − 5.83	Very Low	19.39	0.53	0.059
Distance to Road	0.060	1	0-500	Very Low	1153.67	31.47	0.056
		2	501 − 1000	Low	674.29	18.39	0.096
		3	1,001 − 1,500	Moderate	476.68	13.00	0.157
		4	1,501 − 2,000	High	354.47	9.67	0.257
		5	2,001 − 10,730	Very High	1006.84	27.46	0.434

Table 10. Consistency check of aggregated for flood hazard in the Malda district.

Lambda Max	N	Consistency Index	Consistency Ratio
9.17	9	0.022	0.015

Table 11. Area of flood susceptibility, vulnerability, and risk zonation of Malda district, WB.

Levels	FSZ		FVZ		FRZ
	Area in sq. km	Area in %	Area in sq. km	Area in %	Area in sq. km	Area in %
Very Low	615.40	16.82	613.23	16.77	757.47	20.73
Low	978.71	26.75	1194.40	32.66	1148.70	31.44
Medium	934.01	25.52	992.12	27.13	988.47	27.05
High	728.77	19.92	597.78	16.35	579.71	15.87
Very High	402.35	11.00	259.76	7.10	179.33	4.91
Total Area	3659.23	100.00	3657.28	100.00	3653.68	100.00

Table 12. Comparison of weightage using different methods for flood susceptibility zonation.

Parameters	Saaty (1980)		Ranking Methods of Stillwell (1981)
	Pairwise		Rank Sum (RS)		Rank Reciprocal (RR)
	Direct Rank	(AHP)	(n-rj + 1)	(n-rj + 1)/∑(n-rk + 1)	(1/rj)	(1/rj)/∑(1/rk)
E	1	0.27	12	0.13	1	0.29
S	2	0.19	11	0.12	0.50	0.15
DD	3	0.12	10	0.11	0.33	0.10
DR	3	0.12	10	0.11	0.33	0.10
TWI	4	0.09	9	0.10	0.25	0.07
MNDWI	5	0.06	8	0.09	0.20	0.06
MFI	6	0.04	7	0.07	0.17	0.05
NDVI	7	0.03	6	0.06	0.14	0.04
L	7	0.03	6	0.06	0.14	0.04
TPI	8	0.02	5	0.05	0.13	0.04
SPI	8	0.02	5	0.05	0.13	0.04
STI	8	0.02	5	0.05	0.13	0.04

Table 13. Comparison of weightage using different methods for flood vulnerability zonation.

Parameters	Saaty (1980)		Ranking Methods of Stillwell (1981)
	Pairwise		Rank Sum (RS)		Rank Reciprocal (RR)
	Direct Rank	(AHP)	(n-rj + 1)	(n-rj + 1)/∑(n-rk + 1)	(1/rj)	(1/rj)/∑(1/rk)
TP	1	0.24	9	0.15	1	0.25
PD	1	0.24	9	0.15	1	0.25
LULC	2	0.15	8	0.13	0.50	0.12
DFS	3	0.10	7	0.11	0.33	0.08
DH	3	0.10	7	0.11	0.33	0.08
DR	4	0.06	6	0.10	0.25	0.06
RD	4	0.06	6	0.10	0.25	0.06
ILR	5	0.04	5	0.08	0.20	0.05
ER	6	0.03	4	0.07	0.17	0.04

Figure 8. Effective weight (W) for flood susceptibility parameters.

Table 14. Descriptive Statistics of single parameter sensitivity analysis of flood susceptibility.

Thematic Layers	Empirical Weight (%)	Effective Weight in %
		Min	Max	Mean	SD
Elevation	27%	5.40	71.10	29.26	9.17
Slope	19%	3.00	60.93	23.05	9.50
TWI	9%	1.18	38.54	5.56	3.50
TPI	2%	0.14	10.80	1.61	1.33
NDVI	3%	0.43	11.85	2.27	1.19
MNDWI	6%	0.88	28.19	4.16	2.37
Drainage Density (km/sq km)	12%	1.67	43.23	9.20	5.52
Distance from river (km)	12%	1.30	51.08	13.48	8.15
SPI	2%	0.12	12.17	2.66	1.53
STI	2%	0.13	11.92	3.59	1.46
MFI	4%	0.64	24.05	4.13	2.52
Lithology	3%	0.23	15.88	1.03	1.31

Figure 9. Effective weight (W) for flood vulnerability parameters.

Table 15. Descriptive Statistics of single parameter sensitivity analysis of flood vulnerability.

Thematic Layers	Empirical Weight (%)	Effective Weight in %
		Min	Max	Mean	SD
Total Population	23.50	3.47	58.15	16.46	8.52
Population Density	23.50	3.47	56.89	16.71	8.08
LULC	15.30	1.50	53.83	18.27	7.99
Distance to Flood Shelter	9.60	1.38	47.44	19.96	6.58
Distance to Hospital	9.60	1.13	27.53	6.89	3.95
Distance to Road	6.00	0.83	21.77	5.64	4.50
Road Density	6.00	0.95	25.53	8.38	3.57
Illiteracy Rate	3.80	0.36	19.53	4.90	2.54
Employment Rate	2.70	0.35	19.18	2.79	1.58

Figure 10. Sensitivity index (SI) for flood susceptibility parameters.

Figure 11. Flood susceptibility zonation with each parameter removal.

Table 16. Descriptive Statistics of map removal sensitivity analysis of flood susceptibility.

Thematic Layers	SI Variation in %
	Min	Max	Mean	SD
Elevation	3.7E-06	4.69	1.11	0.76
Slope	0.0E + 00	3.94	0.94	0.65
TWI	6.6E-07	2.18	1.16	0.35
TPI	1.4E-01	1.47	0.96	0.15
NDVI	2.3E-03	1.55	1.01	0.13
MNDWI	3.3E-06	5.43	1.06	0.37
Drainage Density (km/sq km)	0.0E + 00	2.35	1.12	0.47
Distance from river (km)	2.3E-06	3.17	0.86	0.51
SPI	1.5E-03	1.36	0.84	0.16
STI	1.7E-02	1.44	0.72	0.14
MFI	6.7E-06	2.31	0.99	0.28
Lithology	5.9E-04	1.66	1.13	0.13

Table 17. Percentage of changes of flood susceptibility zonation with the removal of each thematic layer.

Thematic Layer	FSZ (%)
	Very Low	Low	Medium	High	Very High
Elevation	+1.79	−7.98	+2.92	+3.14	+4.22
Slope	+8.49	−5.46	−4.46	+6.63	−1.34
TWI	−3.90	−5.47	+0.26	+4.97	+9.68
TPI	−0.60	−4.40	−0.61	+3.40	+6.99
NDVI	−1.73	−4.95	−0.76	+5.05	+7.40
MNDWI	−4.50	−7.27	−0.86	+6.27	+15.19
Drainage Density (km/sq km)	−4.85	−10.29	−5.56	+7.63	+31.56
Distance from river (km)	−2.11	−9.16	−1.66	+9.88	+11.49
SPI	−1.84	−5.39	−0.98	+4.88	+9.37
STI	−1.34	−5.21	−1.21	+4.84	+8.78
MFI	+3.13	−3.58	−0.37	+2.05	+1.03
Lithology	−0.94	−5.03	−0.58	+4.44	+7.00

‘+’ represents increased by area and ‘−‘represents decreased by area

Figure 12. Sensitivity index (SI) for flood vulnerability parameters.

Figure 13. Flood vulnerability zonation with each parameter removal.

Table 18. Descriptive Statistics of map removal sensitivity analysis of flood vulnerability.

Thematic Layers	SI Variation in %
	Min	Max	Mean	SD
Total Population	1.9E-04	4.89	2.80	1.23
Population Density	1.3E-04	5.20	2.99	1.23
LULC	8.4E-05	4.36	1.34	0.87
Distance to Flood Shelter	6.2E-05	3.76	0.68	0.59
Distance to Hospital	1.4E-03	2.72	1.95	0.53
Distance to Road	4.9E-04	1.99	1.28	0.59
Road Density	1.2E-03	1.99	0.93	0.48
Illiteracy Rate	9.6E-04	2.07	1.32	0.34
Employment Rate	1.7E-02	2.02	1.58	0.24

Table 19. Percentage of changes of flood vulnerability zonation with removal of each thematic layer.

Thematic Layer	FVZ (%)
	Very Low	Low	Medium	High	Very High
Total Population	−37.25	−3.32	+25.67	+9.75	−17.26
Population Density	−28.03	+3.32	+20.91	−1.18	−26.17
LULC	+15.69	−4.28	−7.75	−4.88	+23.54
Distance to Flood Shelter	+30.48	+3.34	−15.76	−11.02	−1.74
Distance to Hospital	−12.43	+4.13	+2.19	+3.96	−7.12
Distance to Road	−11.96	+14.13	−3.42	−9.04	−2.38
Road Density	−0.18	+12.18	−4.20	−12.00	−11.93
Illiteracy Rate	+23.86	−0.89	−9.84	−7.05	+1.61
Employment Rate	−13.63	+0.53	+4.32	+2.99	+7.17

‘+’ represents increased by area and ‘- ‘represents decreased by area.

Figure 14. (a) Classification of flood susceptibility zonation, (b) flood vulnerability zonation, (c) ROC-AUC analysis, (d) speedometer shows the AUC.

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