Integrating Analytical Hierarchy Process with GIS and Satellite Remote Sensing to Assess Land Suitability for Sustainable Tea Production in Bangladesh

Abstract

Land suitability evaluation is crucial for assessing environmental limitations that inhibit higher yield and productivity in tea. The aim of this research was to determine the suitable lands for sustainable tea production in the northeastern part of Bangladesh using phenological datasets from remote sensing, geospatial datasets of soil-plant biophysical properties, and expert opinions. Sentinel-2 satellite image datasets were processed to obtain layers for land use and land cover (LULC) as well as the normalized difference vegetation index (NDVI). Data from the Shuttle Radar Topography Mission (SRTM) were processed to generate the elevation layer. Other vector layers of edaphic and climatic parameters were processed in ArcGIS 10.7.1^® software for the respective raster layers. Finally, land suitability classes were obtained from the reclassified raster layers of all parameters along with the results from multicriteria analysis using spatial analysis. The results of the study showed that only 41,460 hectares of land (3.37% of the total land) were in the highly suitable category in the Sylhet region of Bangladesh. The proportions of moderately suitable, marginally suitable, and not suitable land categories for tea cultivation in the Sylhet division were 9.01%, 49.87% and 37.75%, respectively. Thirty-one tea estates were located in highly suitable areas, 79 in moderately suitable areas, 24 in marginally suitable areas, and only 1 in a not suitable area. Yield estimation was performed with the NDVI (R² = 0.69, 0.66, and 0.67) and the LAI (R² = 0.68, 0.65, and 0.63) for 2017, 2018, and 2019. This research suggests that satellite remote sensing and GIS applications with the analytical hierarchy process (AHP) could be used by land policy makers and agricultural land use planners to select suitable lands for increasing tea production.

Appendix 1. Criteria for the Land Suitability Evaluation of Tea

Criteria	Suitability class	Sub-criteria	References
LULC	S1	Tea estates	Su et al. (2016), Su et al. (2017)
	S2	Forest	Su et al. (2016), Su et al. (2017), Hajiboland (2017)
	S3	High agricultural land	Su et al. (2017)
	N	Settlements, water bodies, rivers, and wetlands	Pezeshki (2001), Purnamasari et al. (2019)
NDVI	S1	>0.6	Choudhary et al. (2019)
	S2	0.4–0.6	Choudhary et al. (2019)
	S3	0.4	Choudhary et al. (2019)
	N	<0	Choudhary et al. (2019)
Elevation	S1	>15 m	Hajiboland (2017), Jayasinghe et al. (2019)
	S2	10–15 m	Hajiboland (2017), Jayasinghe et al. (2019)
	S3	7–10 m	Hajiboland (2017), Jayasinghe et al. (2019)
	N	<7 m	Hajiboland (2017), Jayasinghe et al. (2019)
Precipitation	S1	>1800 mm	Gahlod et al. (2017)
	S2	1600–1800 mm	Gahlod et al. (2017)
	S3	1000–1600 mm	Gahlod et al. (2017)
Temperature	S1	18–25 °C	Gahlod et al. (2017)
Slope	S1	5–25°	Jayasinghe et al. (2019)
	S2	<5°	Jayasinghe et al. (2019)
	S3	>25°	Jayasinghe et al. (2019)
Soil texture	S1	scl, l, cl, sl	Gahlod et al. (2017)
	S2	c, sicl, sic	Gahlod et al. (2017)
	S3	c(ss), ls, s	Gahlod et al. (2017)
Soil pH	S1	4.5–5.5	Jayasinghe et al. (2019), Sultana et al. (2014), Hussain et al. (2012), Natesan (1999)
	S2	5.5–7.3	Jayasinghe et al. (2019), Sultana et al. (2014), Hussain et al. (2012), Natesan (1999)
	S3	7.3–8.4	Jayasinghe et al. (2019), Sultana et al. (2014), Hussain et al. (2012), Natesan (1999)
Drainage	S1	Moderately well drained to well drained	Nguyen et al. (2020), Sys et al. (1993)
	S2	Imperfectly drained	Nguyen et al. (2020), Sys et al. (1993)
	S3	Poorly drained	Nguyen et al. (2020), Sys et al. (1993)
	N	Very poorly drained	Sys et al. (1993)
Soil type	S1	Brown hill soils	Egashira et al. (2007)
	S2	Gray piedmont soils	Prokop & Płoskonka (2014), Akhtaruzzaman et al. (2014)
	S3	Non-calcareous alluvium, Brown flood plain soils, Dark gray flood plain soils, gray flood plain soils, acid basin clays, deep-red brown terrace soils	Islam et al. (2017), Egashira et al. (2007), Egashira et al. (1998), Bhuiya (1987)
	N	Peat, water bodies, urban	Islam et al. (2017)
Distance from roads	S1	0–1.0 km	Pramanik (2016)
	S2	1.0–2.0 km	Pramanik (2016)
	S3	2.0–4.0 km	Pramanik (2016)
	N	>4.0 km	Pramanik (2016)
Distance from rivers	S1	0–0.5 km	Pramanik (2016)
	S2	0.5–1.0 km	Pramanik (2016)
	S3	1.0–2.0 km	Pramanik (2016)
	N	>2.0 km	Pramanik (2016)