Estimation of the environment component of the Water Poverty Index via remote sensing in semi-arid zones

Figures & data

Figure 1. Location of the Río Verde aquifer, San Luis Potosí

Table 1. Key components in the Water Poverty Index (WPI) (adapted from Lawrence et al. 2002)

WPI Component	Definition	Sub-components
Environment (E)	Evaluation of environmental integrity related to water	Spatial-temporal analysis of vegetation cover through vegetation indices from satellite data^a: NDVI SAVI LAI CIgreen
Resource (R)	Physical availability of surface and groundwater, considering its use and water balance	Surface water Groundwater Volume used
Access (A)	Level of access to safe water for human use	% of population with access to drinking water % of population with access to water treatment % of agricultural land with access to irrigation
Capacity (C)	Efficacy of the population’s capacity to manage water	Income Mortality rate of children under 5 years of age Education index Gini coefficient
Use (U)	Ways in which water is used for different purposes, including domestic, agricultural and industrial uses	Domestic water use, liters per day Percentage of water used for agriculture, adjusted based on the sector’s contribution to the GDP
Water quality (Q)	Evaluation of water quality for human use	Water quality for domestic and agricultural use WQI SAR

^aThe vegetation indices normalized difference vegetation index (NDVI), soli adjusted vegetation index (SAVI), leaf area index (LAI) and chlorophyll index (CIgreen) are incorporated for the first time in Water Poverti Index assessment in this study.

^bWater quality indices: water quality index (WQI) and sodium adsorption ratio (SAR), domestic and agricultural use, respectively.

Table 2. Changes in vegetation indices normalized difference vegetation index (NDVI), soli adjusted vegetation index (SAVI),  leaf area index (LAI) and chlorophyll index (CIgreen) 2006–2016

	NDVI		SAVI		LAI		CIgreen
	2006	2016	2006	2016	2006	2016	2006	2016
Average	0.047	0.107	0.024	0.058	0.164	0.147	0.081	0.248

Table 3. Correlation matrix for the normalized difference vegetation index (NDVI), soli adjusted vegetation index (SAVI),  leaf area index (LAI) and chlorophyll index (CIgreen) indices

	NDVI	SAVI	LAI	Cigreen
NDVI	1.00
SAVI	0.97	1.00
LAI	0.01	0.02	1.00
Cigreen	0.82	0.85	0.32	1.000

Weights: fac_SAVI = 0.35; fac_Cigreen = 0.35; fac_NDVI = 0.25; facS_LAI = 0.05.

Figure 2. Spatial distribution resulting from components of the study area

Figure 3. Classification of water according to Wilcox

Table 4. Water poverty index values obtained for each component for the Rio Verde Aquifer

Component	X	w	WPI
Environment	0.49	10	56
Resource	0.68	25
Quality	0.51	20
Use	0.38	15
Access	0.72	15
Capacity	0.52	15

Figure 4. Hexagon of the standard Water Poverty Index of the Rio Verde aquifer

Lawrence, P., Meigh, J., and Sullivan, C.A., 2002. The water poverty index: an international comparison. Keele Economics Research Papers. Keele, UK: Keele Economics Department.

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