A geospatial study of the drought impact on surface water reservoirs: study cases from Texas, USA

Figures & data

Figure 1. Location map for the selected lakes in San Angelo and Dallas. The Edwards Plateau Climate Division (marked with light red color) encompasses all lakes in the San Angelo study area, and the North Central Climate Division (indicated with light orange color) comprises the Dallas area lakes. All other climate divisions in Texas are marked with pale yellow color.

Table 1. Statistical results of the accuracy assessment (%) for the selected reservoirs in San Angelo.

Year	Season	E.V. Spence	O.C. Fisher	Oak Creek	Twin Buttes	Nasworthy
2005	Winter	94	96	97	91	99
	Summer	91	95	92	96	99
2006	Winter	91	93	91	93	95
	Summer	99	96	96	92	91
2007	Winter	94	90	96	93	92
	Summer	93	93	96	96	99
2008	Winter	99	98	91	97	97
	Summer	90	97	91	92	95
2009	Winter	98	92	93	97	97
	Summer	92	94	92	90	98
2010	Winter	93	92	99	91	97
	Summer	90	97	91	93	94
2011	Winter	91	98	93	94	99
	Summer	92	97	95	94	99
2012	Winter	91	98	91	98	98
	Summer	90	97	94	91	99
2013	Winter	91	97	93	95	94
	Summer	93	91	95	99	96
2014	Winter	93	95	99	93	98
	Summer	93	90	95	94	91
2015	Winter	99	91	99	98	95
	Summer	90	92	93	90	99
2016	Winter	91	98	93	92	90
	Summer	96	95	97	91	92

Table 2. Statistical results of the accuracy assessment (%) for the selected reservoirs in Dallas.

Year	Season	Ray Roberts	Lewisville	Grapevine	Kiowa	North
2005	Winter	97	93	92	98	97
	Summer	94	93	96	98	95
2006	Winter	90	96	92	94	91
	Summer	90	92	91	95	92
2007	Winter	98	93	93	91	94
	Summer	98	95	94	90	92
2008	Winter	95	91	91	96	93
	Summer	99	99	94	90	94
2009	Winter	98	91	99	99	97
	Summer	92	96	92	99	90
2010	Winter	90	93	90	99	91
	Summer	90	91	95	99	90
2011	Winter	90	99	98	98	92
	Summer	93	94	96	99	97
2012	Winter	95	98	93	92	93
	Summer	91	93	93	90	91
2013	Winter	90	91	97	92	99
	Summer	93	91	97	99	93
2014	Winter	92	90	98	99	99
	Summer	99	94	94	92	93
2015	Winter	90	91	93	91	96
	Summer	98	95	90	90	97
2016	Winter	97	95	96	93	91
	Summer	95	96	95	92	97

Table 3. Seasonal oscillations (%) in the surface water area of the selected reservoirs in San Angelo. The percentage of surface water area change is calculated with respect to the total possible surface area prescribed by the Texas Water Development Board.

Year	Season	Oak Creek	E.V. Spence	Nasworthy	Twin Buttes	O.C. Fisher
2005	Winter	28.8	58.8	82.1	30.2	15.9
	Summer	33.3	60.6	76.7	33.2	24.6
2006	Winter	35.9	64.5	75.8	37.3	24.9
	Summer	30.5	57.4	77.5	30.9	19.9
2007	Winter	22.1	55.2	79.7	33.3	17.1
	Summer	88.5	61.9	80.4	43.7	22.7
2008	Winter	88.3	56.8	76.5	49.4	19.6
	Summer	81.9	53.4	74.2	39.2	15.2
2009	Winter	79.4	47.5	77.0	38.0	12.8
	Summer	73.3	37.8	73.8	33.6	11.1
2010	Winter	70.7	29.7	80.1	34.4	10.4
	Summer	70.7	28.1	74.6	30.0	8.2
2011	Winter	68.5	24.4	79.5	27.9	6.0
	Summer	56.6	13.4	78.6	16.9	1.3
2012	Winter	48.3	9.0	85.4	15.3	2.4
	Summer	41.1	9.0	78.7	12.4	0.1
2013	Winter	38.4	33.4	82.4	15.0	0.2
	Summer	34.0	31.7	78.5	5.3	0.6
2014	Winter	21.0	26.9	76.8	8.4	0.1
	Summer	28.2	19.5	80.0	18.4	5.4
2015	Winter	25.0	24.6	80.3	16.9	0.4
	Summer	41.7	40.2	81.4	21.6	26.2
2016	Winter	46.0	48.2	80.7	18.6	32.5
	Summer	59.4	49.2	79.6	24.1	30.1

Figure 2. Surface water area oscillations in the O.C. Fisher Lake from winter acquisitions of each year during the study period (2005–2016). Dates are dd/mm/yyyy and the image from 2015 is used in the background because it has 0% cloud cover.

Figure 3. A comparison of oscillations in the surface water area and the volume of the E.V. Spence and the O.C. Fisher Lakes between 2005 and 2016.

Table 4. Seasonal changes (%) in the surface water area of the selected reservoirs in Dallas during 2005–2016. The percentage of surface water area change is calculated with respect to the total possible surface area prescribed by the Texas Water Development Board.

Year	Season	Grapevine	Ray Roberts	Lewisville	Kiowa	North
2005	Winter	89.5	88.4	81.3	79.4	91.7
	Summer	85.3	93.6	84.8	86.1	93.3
2006	Winter	80.4	78.9	64.7	91.9	90.5
	Summer	74.3	84.1	71.6	84.8	84.6
2007	Winter	72.4	80.7	82.5	87.8	84.0
	Summer	94.8	96.1	94.4	71.1	65.3
2008	Winter	91.7	85.9	76.9	74.1	91.8
	Summer	83.6	95.0	88.4	82.9	88.6
2009	Winter	78.5	91.5	83.1	85.0	88.9
	Summer	86.7	95.4	92.2	84.1	83.9
2010	Winter	91.4	95.5	93.8	81.6	77.5
	Summer	90.7	94.4	90.2	82.3	77.0
2011	Winter	83.0	92.4	87.6	78.0	71.8
	Summer	88.4	90.1	83.9	85.8	73.0
2012	Winter	89.7	82.3	76.3	77.3	68.0
	Summer	87.3	94.5	88.9	84.0	72.9
2013	Winter	81.8	88.6	78.8	84.8	68.4
	Summer	78.7	86.0	78.8	88.6	68.3
2014	Winter	75.9	81.2	77.2	88.7	67.0
	Summer	76.3	79.1	78.3	88.8	24.5
2015	Winter	72.3	80.7	78.6	87.8	21.7
	Summer	97.8	98.0	97.1	83.7	29.6
2016	Winter	97.9	98.1	94.8	83.5	30.1
	Summer	93.5	96.2	93.6	83.8	28.7

Figure 4. Surface water area changes in the Grapevine Lake from winter acquisitions of each year during 2005–2016. Dates are dd/mm/yyyy and the image from 2015 is used in the background because it has no cloud cover.

Figure 5. A comparison of oscillations in the surface water area and the volume of the Lewisville and the Ray Roberts Lakes.

Figure 6. (a) Palmer drought indices for the Edwards Plateau climate division (marked with light red color in Figure 1) and surface water area changes in the San Angelo lakes. (b) Palmer drought indices for the North Central Texas division (marked with light orange color in Figure 1) and surface water area changes in the Dallas reservoirs.

Figure 7. (a) The relationship between the surface water area and the average of evaporation recorded on site daily at the Grapevine and the O.C. Fisher Lakes by the Corps of Engineers and the Texas Water Development Board, respectively. (b) The relationship between changes in the surface water area and the average of daily discharge (the total m³/day) measured at the Grapevine and the O.C. Fisher Lakes by the Corps of Engineers and the Texas Water Development Board, respectively.