Risk evaluation of solar greenhouse cucumbers low temperature disaster based on GIS spatial analysis in Tianjin, China

Figures & data

Figure 1. Study area.

Table 1. Error analysis of hourly air temperature simulation result of traditional second generation greenhouse.

Maximum error（°C）	Minimum error（°C）	Average error（°C）	Relative error (%)	Standard deviation（°C）
−1.92	0.07	−0.35	4	3.03

Table 2. Parameters of three types of solar greenhouses with different heat retaining abilities.

Greenhouse type	Length (m)	Span (m)	Spine height (m)	Back wall height (m)	Back roof projection (m)	Side wall thickness (m)	Side wall material	Back wall thickness (m)	Back wall material	Back slope thickness (m)	Back slop material	Heat Curtain thickness (m)	Heat retaining performance
Xiqing traditional second generation greenhouse	80	6.5	3.1	2.5	0.67	0.37	Brick	0.5	Brick	0.15	Cement	0.08	Poor
Wuqing new type greenhouse	65	9.97	5.22	3.72	1.65	0.5	±	0.5	Brick + polyphenyl board	0.2	Cement	0.1	Moderate
Baodi traditional cob wall greenhouse	85	9	4.5	4.2	0.88	0.9	±	2.05	Soil	0.5	Soil	0.09	Excellent

Note: Thermal conductivity of wall material: brick – 0.75 W/m·K; soil – 0.23 W/m·K; polyphenyl board – 0.04 W/m·K; cement – 1.28 W/m·K.

Table 3. Development phase of solar greenhouse cucumber in Tianjin.

Development phase	Time
Seeding phase	October 1–October 25
Flowering phase	October 26–November 5
Fruiting phase	November 6–February 28

Table 4(a). Greenhouse inside disaster indexes caused cucumber low temperature disaster for different development phases.

Development phase Disaster degree	Seeding phase (duration)	Flowering phase (duration)	Fruiting phase (duration)
Mild	11 °C < = T< =15 °C (72 h)	10 °C < =T< =14 °C (72 h)	9 °C < = T< =13 °C (72 h)
Moderate	8 °C < = T< =11 °C (48 h)	6 °C < =T< =10 °C (48 h)	5 °C < = T< =9 °C (48 h)
Severe	T < 8 °C (24 h)	T < 6 °C (24 h)	T < 5 °C (24 h)

Table 4(b). Greenhouse outside disaster indexes caused cucumber low temperature disaster of traditional second generation greenhouse.

Development phase Disaster degree	Seeding phase (duration)	Flowering phase (duration)	Fruiting phase (duration)
Mild	11 °C < = T< =15 °C (72 h)	9.2 °C < =T< =12.6 °C (72 h)	0.4 °C < =T< =4.4 °C (72 h)
Moderate	8 °C < = T< =11 °C (48 h)	5 °C < =T< = 9.2 °C (48 h)	−3.1 °C < =T< =0.4 °C (48 h)
Severe	T < 8 °C (24 h)	T < 5 °C (24 h)	T< −3.1 °C (24 h)

Table 4(c). Greenhouse outside disaster indexes caused cucumber low temperature disaster of new type greenhouse.

Development phase Disaster degree	Seeding phase (duration)	Flowering phase (duration)	Fruiting phase (duration)
Mild	11 °C < =T< =15 °C (72 h)	/	−2.8 °C < =T< =1.6 °C 72 h)
Moderate	8 °C < =T< =11 °C (48 h)	/	−3.4 °C < =T< =−2.8 °C (48 h)
Sever	T < 8 °C (24 h)	/	T< −3.4 °C (24 h)

Table 4(d). Greenhouse outside disaster indexes caused cucumber low temperature disaster of traditional cob wall greenhouse.

Development phase Disaster degree	Seeding phase (duration)	Flowering phase (duration)	Fruiting phase (duration)
Mild	11 °C < =T< =15 °C (72 h)	/	/
Moderate	8 °C < =T< =11 °C (48 h)	/	/
Severe	T < 8 °C (24 h)	/	/

Figure 4. Comprehensive risk distribution of cucumber low temperature disaster of traditional second generation greenhouse (a), new type greenhouse (b) and the disaster risk zone for them (c for traditional second generation greenhouse and d for new type greenhouse). *The meanings of TS, NT and CP refer to Figure 2; CP-risk represents comprehensive disaster risk index.