Spatio-temporal monitoring of droughts in Iran using remote-sensing indices

doi:10.21203/rs.3.rs-1842124/v1

Download PDF

Research Article

Spatio-temporal monitoring of droughts in Iran using remote-sensing indices

https://doi.org/10.21203/rs.3.rs-1842124/v1

This work is licensed under a CC BY 4.0 License

Journal Publication

published 21 Feb, 2023

Read the published version in Natural Hazards →

You are reading this latest preprint version

This study monitored spatially drought in Iran country using distance measurement indicators. Five drought indicators measured from 2016 to 2020 were used: temperature condition index (TCI), vegetation condition index (VCI), vegetation health index (VHI), precipitation condition index (PCI), and standardized precipitation index (SPI). The TCI revealed that the largest percentage of the region classified as “severe drought” occurred in 2020. The VCI indicated that the largest portion of the country (73.30%) experiencing “moderate drought” occurred in 2018. The VHI indicated that vegetation stress increased throughout the region, and areas of severe and moderate drought reached their greatest extents in the mentioned years. Although significant droughts have occurred primarily in the central, eastern, and southeastern parts of Iran, mild droughts have occurred in northern Iran as well. The PCI indicated that rainfall amounts have diminished in most of the country during the period of study. The SPI showed that northern Iran received heavy rain, and was the only region classified as “extremely wet.” Most of the rest of Iran were “moderately dry.” The analysis of the VHI index for agricultural plants showed that 27.71% of Iran's agricultural regions experienced “critical drought” conditions, this included the provinces of Razavi Khorasan, Hamadan, and Khozestan. The study can provide a baseline for the selection of the most useful drought-monitoring indicators and can enable a deeper understanding of drought in arid and semi-arid regions.

Drought

Iran

Spatio-temporal analysis

VCI

VHI

SPI

Table 1

Values of the Coefficients Used in the Split-Window Algorithm

Coefficient	Value
C₀	-0.268
C₁	1.378
C₂	0.183
C₃	54.300
C₄	-2.238
C₅	-129.200
C₆	16.400

Table 2

The Annual Percentage of Country by Temperature Condition Index (TCI) Class from 2016 to 2020

Class	2016	2017	2018	2019	2020
Extreme drought (<10)	15.72	14.33	14.28	12.54	19.19
Severe drought (11-20)	33.70	31.25	32.47	35.74	41.05
Moderate drought (21-30)	28.05	31.33	30.91	32.20	29.45
Slight drought (31-40)	16.58	18.85	17.49	14.74	10.02
No drought (>40)	5.96	4.24	4.85	4.78	0.28

Table 3

The Annual Percentage of Country by Vegetation Condition Index (VCI) Class from 2016 to 2020

Class	2016	2017	2018	2019	2020
Extreme drought (<10)	0.08	0.10	0.04	0.15	0.16
Severe drought (11-20)	52.55	49.94	0.10	47.03	52.89
Moderate drought (21-30)	35.46	38.81	73.30	38.59	35.82
Slight drought (31-40)	9.28	8.76	22.99	11.35	8.60
No drought (>40)	2.61	2.39	3.57	2.88	2.53

Table 4

The Annual Percentage of Country by Vegetation Health Index (VHI) Class from 2016 to 2020

Class	2016	2017	2018	2019	2020
Extreme drought (<10)	27.41	26.81	27.61	25.35	24.92
Severe drought (11-20)	38.59	38.08	36.36	40.83	40.67
Moderate drought (21-30)	23.83	26.20	24.51	24.25	24.38
Slight drought (31-40)	7.78	6.95	9.09	7.24	7.73
No drought (>40)	2.39	1.95	2.42	2.32	2.30

Table 5

The Annual Percentage of Country by Precipitation Condition Index (PCI) Class from 2016 to 2020

Class	2016	2017	2018	2019	2020
Extreme drought (<10)	63.42	50.50	58.59	51.10	58.50
Severe drought (11-20)	18.60	34.41	20.61	32.06	26.81
Moderate drought (21-30)	12.73	11.41	15.61	13.27	11.58
Slight drought (31-40)	3.34	2.81	3.77	2.48	2.36
No drought (>40)	1.91	0.87	1.42	1.09	0.76

Table 6

The Annual Percentage of Country by Standardized Precipitation Index (SPI) Class from 2016 to 2020

Class	2016	2017	2018	2019	2020
Mild drought	63.42	50.50	58.59	55.38	58.50
Near normal conditions	26.84	40.68	28.37	34.38	32.90
Moderately wet	3.96	3.36	6.22	4.93	3.58
Very wet	1.71	1.56	2.56	1.87	1.42
Extremely wet	4.07	3.90	4.26	3.44	3.61

Table 7

The Percentage of Land Use/Land Cover Classes by Province in 2020

Province	Water	Trees	Grassland	Flooded Vegetation	Agriculture	Rangeland	Built Area	Bare land
Alborz	0.32	0.47	0.09	0.00	12.43	66.29	11.33	9.07
Ardabil	0.16	0.60	0.70	0.01	35.60	59.32	2.71	0.90
Bousher	1.61	0.03	0.00	0.01	3.45	84.01	2.28	8.60
Charmahal Bakhtiyari	0.33	0.40	0.01	0.09	10.43	82.29	1.98	4.46
East Azerbaijan	0.15	1.68	0.11	0.01	24.37	65.80	2.81	5.06
Ilam	0.59	0.06	0.00	0.00	7.81	86.32	1.08	4.13
Esfahan	0.08	0.03	0.00	0.00	4.09	52.76	1.81	41.22
Fars	0.36	0.05	0.01	0.01	7.60	82.32	1.60	8.05
Guilan	1.37	42.09	1.50	0.27	23.23	23.00	8.36	0.17
Golestan	1.49	16.84	0.08	0.10	29.90	47.33	2.75	1.51
Hamadan	0.05	0.46	0.01	0.00	54.43	37.13	2.64	5.27
Hormozgan	0.78	0.02	0.00	0.02	0.94	81.69	1.55	15.00
Kerman	0.07	0.01	0.00	0.00	2.93	72.56	1.03	23.40
Kermanshah	0.17	0.21	0.01	0.00	34.80	59.70	2.05	3.07
Khozestan	6.07	0.21	0.23	1.27	19.87	64.51	2.08	5.77
Kohgiluyeh and Boyer-Ahmad	0.32	1.01	0.00	0.00	2.46	92.35	1.69	2.16
North Khorasan	0.04	0.54	0.00	0.00	11.69	82.62	1.22	3.89
Razavi Khorasan	0.04	0.08	0.00	0.00	19.18	68.43	1.55	10.71
South Khorasan	0.03	0.00	0.00	0.00	2.33	73.86	0.40	23.38
Kordestan	0.36	0.58	0.02	0.03	48.52	46.35	1.67	2.46
Lorestan	0.27	0.44	0.01	0.00	18.33	75.76	1.69	3.51
Markazi	0.13	0.11	0.02	0.01	25.84	61.00	2.16	10.75
Mazandarn	1.06	38.13	0.41	0.01	17.44	34.52	6.94	1.46
Qazvin	0.12	0.47	0.01	0.00	32.81	61.42	2.80	2.38
Qom	0.17	0.08	0.01	0.00	7.61	45.94	2.39	43.79
Semnan	0.05	0.15	0.00	0.00	1.67	36.22	0.34	61.56
Sistan and Baluchestan	0.41	0.01	0.01	0.03	1.00	74.34	0.57	23.63
Tehran	0.14	0.30	0.06	0.00	12.83	61.16	14.12	11.38
West Azerbaijan	0.33	0.61	0.04	0.03	27.55	65.03	2.96	3.43
Yazd	0.15	0.00	0.00	0.00	0.63	48.87	0.55	49.79
Zanjan	0.13	0.26	0.01	0.00	37.77	56.07	1.88	3.87

Table 8

Critical Drought Conditions in Agricultural Areas of the Provinces of Iran

Province	Area (Km²)	Agricultural area	H+ VH classes area	%H+ VH classes
Razavi Khorasan	118851.44	22800.25	7519.93	32.98
Hamadan	19367.90	10542.79	5580.23	52.93
Khozestan	64055.00	12727.00	4843.14	38.05
Markazi	29126.56	7526.11	4642.67	61.69
Kordestan	29136.55	14135.99	4179.27	29.56
Fars	122607.94	9322.30	2571.06	27.58
Zanjan	21773.29	8223.98	2540.00	30.89
Lorestan	28293.99	5186.27	2229.34	42.99
West Azerbaijan	37411.39	10307.00	1988.78	19.30
Kerman	180725.57	5288.75	1923.00	36.36
East Azerbaijan	45650.47	11126.95	1660.61	14.92
Esfahan	107017.65	4377.79	1335.18	30.50
South Khorasan	95384.97	2223.94	1024.14	46.05
Kermanshah	25009.27	8702.25	1010.68	11.61
Ilam	20132.84	1571.56	756.99	48.17
Bousher	22742.74	784.57	703.99	89.73
Sistan and Baluchestan	181785.28	1811.65	608.56	33.59
Qazvin	15567.30	5107.27	431.56	8.45
Qom	11526.26	877.47	418.40	47.68
Semnan	97490.81	1629.56	406.90	24.97
Yazd	129284.86	814.32	334.38	41.06
Hormozgan	70697.28	664.92	281.88	42.39
Charmahal Bakhtiyari	16328.35	1703.38	277.57	16.30
Tehran	13692.41	1757.02	262.05	14.91
North Khorasan	28434.31	3324.76	234.68	7.06
Ardabil	17799.99	6336.60	77.85	1.23
Alborz	5121.69	636.78	74.31	11.67
Golestan	20367.13	6089.07	69.72	1.14
Kohgiluyeh and Boyer-Ahmad	15504.07	381.03	57.01	14.96
Mazandarn	23841.64	4158.34	6.20	0.15
Gilan	14041.89	3262.63	0.57	0.02

Download PDF

Journal Publication

published 21 Feb, 2023

Read the published version in Natural Hazards →

Editorial decision: Minor revisions
28 Sep, 2022
Reviewers agreed at journal
17 Jul, 2022
Reviewers invited by journal
17 Jul, 2022
Editor assigned by journal
11 Jul, 2022
First submitted to journal
09 Jul, 2022

You are reading this latest preprint version

Spatio-temporal monitoring of droughts in Iran using remote-sensing indices

Status:

Journal Publication

Version 1

Abstract

Figures

Full Text

Tables

Status:

Journal Publication

Version 1