Figure 1.
(a) Geographic location and administrative districts of the study area in Hanoi city, (b) comparison of Hanoi before and after expansion of the administrative boundaries in 2008.
Figure 1.
(a) Geographic location and administrative districts of the study area in Hanoi city, (b) comparison of Hanoi before and after expansion of the administrative boundaries in 2008.
Figure 2.
Flowchart of this study.
Figure 2.
Flowchart of this study.
Figure 3.
(a) Total population (thousands), (b) population density (people/km2), and (c) population density map in 2016 (people/km2) in Hanoi from 1999 to 2016.
Figure 3.
(a) Total population (thousands), (b) population density (people/km2), and (c) population density map in 2016 (people/km2) in Hanoi from 1999 to 2016.
Figure 4.
Variances in socio-economic indicators of Hanoi from 1960 to 2013, (a) newly built area of residential housing in the year (thousand m2), (b) industrial establishment (number of establishment), and (c) electricity per capita (Kwh/pers).
Figure 4.
Variances in socio-economic indicators of Hanoi from 1960 to 2013, (a) newly built area of residential housing in the year (thousand m2), (b) industrial establishment (number of establishment), and (c) electricity per capita (Kwh/pers).
Figure 5.
Results of land use/land cover classification in Hanoi in 1999, 2009, and 2016.
Figure 5.
Results of land use/land cover classification in Hanoi in 1999, 2009, and 2016.
Figure 6.
Temporal variations of seven LULC types in proportion based on the results of
Figure 5.
Figure 6.
Temporal variations of seven LULC types in proportion based on the results of
Figure 5.
Figure 7.
NDVI maps of Hanoi from Landsat data in 1999, 2009 and 2016.
Figure 7.
NDVI maps of Hanoi from Landsat data in 1999, 2009 and 2016.
Figure 8.
Normalized difference built-up index (NDBI) maps of Hanoi from Landsat data in 1999, 2009 and 2016.
Figure 8.
Normalized difference built-up index (NDBI) maps of Hanoi from Landsat data in 1999, 2009 and 2016.
Figure 9.
Retrievals of the land surface temperature (LST) map in Hanoi from Landsat data in 1999, 2009, and 2016.
Figure 9.
Retrievals of the land surface temperature (LST) map in Hanoi from Landsat data in 1999, 2009, and 2016.
Figure 10.
Identified UHI zones of Hanoi in 1999, 2009, and 2016.
Figure 10.
Identified UHI zones of Hanoi in 1999, 2009, and 2016.
Figure 11.
Associations of LST with LULC types in Hanoi in 1999, 2009, and 2016.
Figure 11.
Associations of LST with LULC types in Hanoi in 1999, 2009, and 2016.
Figure 12.
Relationships among LST, normalized difference vegetation index (NDVI), and NDBI in Hanoi; (a), (b), and (c) LST and NDVI in 1999, 2009, and 2016, respectively; (d), (e), and (f), LST and NDBI in 1999, 2009, and 2016, respectively.
Figure 12.
Relationships among LST, normalized difference vegetation index (NDVI), and NDBI in Hanoi; (a), (b), and (c) LST and NDVI in 1999, 2009, and 2016, respectively; (d), (e), and (f), LST and NDBI in 1999, 2009, and 2016, respectively.
Figure 13.
Correlations of UHI in Hanoi with (a) newly built area of residential housing in the year (thousand m2), (b) industrial establishment (number of establishment), and (c) electricity per capita (Kwh/pers) urbanization indicators.
Figure 13.
Correlations of UHI in Hanoi with (a) newly built area of residential housing in the year (thousand m2), (b) industrial establishment (number of establishment), and (c) electricity per capita (Kwh/pers) urbanization indicators.
Figure 14.
Annual mean air temperature (°C) in four stations of Hanoi (Lang, Ha Dong, and Son Tay stations during the period 1999–2016 and Ba Vi station during the period from 1999–2010).
Figure 14.
Annual mean air temperature (°C) in four stations of Hanoi (Lang, Ha Dong, and Son Tay stations during the period 1999–2016 and Ba Vi station during the period from 1999–2010).
Figure 15.
Variations of annual air temperature (°C) between the Lang station and the Son Tay station from 1999 to 2016.
Figure 15.
Variations of annual air temperature (°C) between the Lang station and the Son Tay station from 1999 to 2016.
Figure 16.
UTFVI maps of Hanoi in 1999, 2009, and 2016.
Figure 16.
UTFVI maps of Hanoi in 1999, 2009, and 2016.
Figure 17.
Changes in (a) annual mean temperature (°C), (b) total rainfall (mm), (c) relative humidity (%) during the period 1961–2016, and (d) wind speed (m/s) during the period 1961–2001 in the Lang station and the Son Tay station.
Figure 17.
Changes in (a) annual mean temperature (°C), (b) total rainfall (mm), (c) relative humidity (%) during the period 1961–2016, and (d) wind speed (m/s) during the period 1961–2001 in the Lang station and the Son Tay station.
Table 1.
The Landsat imagery datasets used in this study.
Table 1.
The Landsat imagery datasets used in this study.
Sensor | Scene ID | Acquisition date | Season |
---|
Landsat 5 TM | LT51270451999266BKT00 | 23/09/1999 | Autumn |
LT51270461999266BKT00 |
Landsat 5 TM | LT51270452009309BJC00 | 05/11/2009 | Autumn |
LT51270462009309BJC00 |
Landsat 8 OLI/TIRS | LC81270452016281LGN01 | 07/10/2016 | Autumn |
LC81270462016281LGN01 |
Table 2.
Eight categories of land use/land cover classes that were used in this study.
Table 2.
Eight categories of land use/land cover classes that were used in this study.
| Classes | Include |
---|
1 | Residential | Rural residential land and urban residential land |
2 | Industrial, Commercial | Land for industrial parks, industrial clusters, export processing zones; land for trading and service |
3 | Active agriculture | Land for cultivation of perennial trees, land for cultivation of annual crops, paddy land |
4 | Inactive agriculture (Wetland and Dry land) | Wetland—Paddy land: pump water in the field to prepare for farming works Dry land—Land for cultivation of perennial trees, land for cultivation of annual crops |
5 | Water | Land with rivers, streams, canals, springs (located in rivers, natural lakes) |
6 | Forestry | Land for special-use forests Land for protection forests Land for production forests |
7 | Sandbars | Riparian land |
8 | Bare soil | Unused land and Unused Mountain Land |
Table 3.
Thresholds of the six urban thermal field variance index (UTFVI) levels used in this study.
Table 3.
Thresholds of the six urban thermal field variance index (UTFVI) levels used in this study.
UTFVI | Urban Heat Island (UHI) Phenomenon | Ecological Evaluation Index |
---|
<0.000 | None | Excellent |
0.000–0.005 | Weak | Good |
0.005–0.010 | Middle | Normal |
0.010–0.015 | Strong | Bad |
0.015–0.020 | Stronger | Worse |
>0.020 | Strongest | Worst |
Table 4.
Results of validations of land use/land cover (LULC) classification in 2016.
Table 4.
Results of validations of land use/land cover (LULC) classification in 2016.
Types of LULC | User’s (%) | Producer’s (%) |
---|
Residential | 94 | 96 |
Industrial | 93 | 92 |
Active agriculture land | 90 | 94 |
Inactive agriculture land | 81 | 78 |
Water | 88 | 90 |
Forestry | 94 | 94 |
Sand-bar | 96 | 98 |
Bare soil | 88 | 84 |
Overall Accuracy (%) | 90.75 |
Kappa Index | 0.88 |
Table 5.
Comparisons of LST retrievals with air temperature from meteorology stations of Hanoi.
Table 5.
Comparisons of LST retrievals with air temperature from meteorology stations of Hanoi.
Land surface temperature validation (°C) |
---|
Station | 23/09/1999 | 05/11/2009 | 07/10/2016 |
---|
Retrieved LST | Air temperature AT | Difference LST-AT | Retrieved LST | Air temperature AT | Difference LST-AT | Retrieved LST | Air temperature AT | Difference LST-AT |
---|
Lang | 27.92 | 26.4 | 1.52 | 25.88 | 23.1 | 2.78 | 28.49 | 26.7 | 1.79 |
Ha Dong | 26.87 | 25.7 | 1.17 | 25.34 | 22 | 3.34 | 27.23 | 26 | 1.23 |
Son Tay | 25.9 | 25.6 | 0.3 | 22.76 | 21.5 | 1.26 | 25.84 | 25.3 | 0.54 |
Ba Vi | 24.88 | 23.8 | 1.08 | 22.75 | 21 | 1.75 | 25.17 | 24.1 | 1.07 |
Table 6.
Temporal fractions of the Urban Heat Island zone in Hanoi (1999, 2009 and 2016).
Table 6.
Temporal fractions of the Urban Heat Island zone in Hanoi (1999, 2009 and 2016).
Class | 1999 (%) | 2009 (%) | 2016 (%) |
---|
UHI | 10.98 | 25.36 | 31.83 |
Non-UHI | 89.02 | 74.64 | 68.17 |