Calculations For Water-balance, Water Pressure, And Glacier Retreat

1.Presents the precipitation and evaporation data for a fictitious location called Azzoca Town.  From this data do the following:

Calculate the difference between precipitation (PRECIP) and potential evapotranspiration (PE) for the city listed below.  Record the plus or minus value for each moth.  January, February and June are already calculated.  Complete the remainder of the water-balance table. 

When does this city experience a net supply of water? List the months

When does this city experience a net demand for water? List the months 

What occurs during the warm months from June through September 

What is the total AE for the year? 

What is the total Deficit for the year?

What is the total Surplus for the year?

Table 3.1: Water-balance table for Azzoca town.  Values are in mm.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sept	Oct	Nov	Dec
Precip	97	99	97	84	104	97	132	112	66	66	66	99
PE	7	8	24	57	97	132	150	133	99	55	12	7
Precip – PE	+90	+91				-35
Storage	100	100				65
Change in Storage	0	0				-35
AE	7	8				132
Deficit	0	0				0
Surplus	90	91				0

2.Given the following depths of locations in the world’s oceans, calculate the water pressure in kg/cm². More information on the calculations can be found in “Crunch the Numbers” found on page 332 of the textbook. 

Puerto Rico Trench (located between the Caribean Ocean and Atlantic Ocean) – depth of 8648 m

Litke Deep (located in the Eurasian Basin of the Arctic Ocean) – depth of 5450 m

Halocline of the tropical ocean – depth of 1000 m

Mesopelagic zone – depth of 250 m

Depth of penetration of red wavelengths – depth of 20 m

3.Table 3.2 lists the annual altitude of the equilibrium line for the Devon Island glacier in Canada.  For this data, answer the following:

calculate the annual retreat or advancement of the equilibrium line.  Positive values indicate advancement and negative retreat of the glacier.  Present the data in a table. 

describe the overall pattern(s) of the change in the glacier.  Make sure to relate the change in the equilibrium line to potential changes in the zone of ablation and accumulation

what are some local or global factors that might have produced the observed changes in the glacier

Water-balance table for Azzoca town

1.Presents the precipitation and evaporation data for a fictitious location called Azzoca Town.  From this data do the following:

Calculate the difference between precipitation (PRECIP) and potential Evapotranspiration (PE) for the city listed below.  Record the plus or minus value for each moth.

January, February and June are already calculated.  Complete the remainder of the water-balance table.  (4 marks)Table 3.1: Water-balance table for Azzoca town.  Values are in mm.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sept	Oct	Nov	Dec
Precip	97	99	97	84	104	97	132	112	66	66	66	99
PE	7	8	24	57	97	132	150	133	99	55	12	7
Precip – PE	+90	+91	+73	+27	+7	-35	-18	-121	-33	+ 11	+54	+92
Storage	100	100	100	100	100	65	65	65	65	100	100	100
Change in Storage	0	0	0	0	0	-35	0	0	0	+35	0	0
AE	7	8	24	57	97	132	150	133	99	55	12	7
Deficit	0	0	0	0	0	0	0	0	0	0	0	0
Surplus	90	91	73	27	7	0	0	0	0	11	54	92

When does this city experience a net supply of water? List the months

January, February, March, April, May, October, November and December. These are the months when precipitation is higher than potential evapotranspiration. The supply of water during this period is high.

When does this city experience a net demand for water? List the months

June, July, August and September. Net demand of water is experienced when demand for water is higher than supply. They are the months when net precipitation is negative net precipitation that occurs when evapotranspiration is higher than precipitation.

What occurs during the warm months from June through September

Warm temperatures lead to higher rates of evaporation which increases the amount of water present in the air. The higher rates of moisture in the atmosphere increases the rainfall intensity (Veblen, Young, & Orme, 2015). From the data above, there precipitation recorded between June and September were higher. However, rates of potential evapotranspiration is also higher when temperatures are high. The net effect of warm temperature is a negative

What is the total AE for the year?

Total AE=

              = 7+8+24+57+97+132+150+133+99+55+12+7

              = 781

What is the total Deficit for the year?

Total Deficit for the year= sum of monthly deficits

                                       = 12(0)

                                       = 0

What is the total Surplus for the year? 

Total surplus of the year= Sum of monthly surplus

               = 90+91+73+27+7+11+54+92

                                      =445

2.Given the following depths of locations in the world’s oceans, calculate the water pressure in kg/cm². More information on the calculations can be found in “Crunch the Numbers” found on page 332 of the textbook. 

Puerto Rico Trench (located between the Caribbean Ocean and Atlantic Ocean) – depth of 8648 m

To find the pressure of water given the depth of the ocean, two procedures are necessary.  First, the number of bars is calculated by dividing depth of ocean by 10m. Secondly, Pressure in Kg/cm³ is obtained by multiplying number of bars by 1.

Hence at 8648 m,

Bars= 8648/10=864.8

Pressure= 864.8*1=864.8Kg/cm³

Litke Deep (located in the Eurasian Basin of the Arctic Ocean) – depth of 5450 m

Bars= 5450/10=545 Bars

Pressure of water= 545* 1= 545Kg/cm³

Halocline of the tropical ocean – depth of 1000 m

Bars= 1000/10=100

Pressure of water= 100*1= 100Kg/cm³

Mesopelagic zone – depth of 250 m

Bars= 250m/10= 25 Bars

Pressure= 25*1=25Kg/cm³

Depth of penetration of red wavelengths – depth of 20 m

Bars= 20m/10= 2 Bars

Pressure= 2*1= 2Kg/cm³

3.Table lists the annual altitude of the equilibrium line for the Devon Island glacier in Canada.  For this data, answer the following:

Calculate the annual retreat or advancement of the equilibrium line.  Positive values indicate advancement and negative retreat of the glacier.  Present the data in a table.

Year	ELA	Change in ELA
1961	1323	NA
1962	1510	1510-1323 = 187
1963	744	744-1510 = -766
1964	610	610-744 =- 866
1965	700	700-610= 90
1966	1230	1230-700=530
1967	1100	1100-1230=-130
1968	1253	1253-1100=153
1969	1368	=1368-1253=115
1970	910	=910-1368=-458
1971	1167	1167-910=257
1972	920	920-1167=-247
1973	1200	1200-920= 280
1974	1199	1199-1200=-1
1975	1092	1092-1199= -107
1976	579	579-1092=-513
1977	1360	1360-579=781
1978	1000	1000-1360=-360
1979	920	920-1000=-80
1980	1130	1130-920= 210
1981	1300	1300-1130=170
1982	1240	1240-1300=-60
1983	840	840-1240=-400
1984	1140	1140-840=300
1985	1220	1220-1140=80
1986	670	670-1220=-550
1987	900	900-670=230
1988	1265	1265-900=365
1989	1140	1140-1265=-125
1990	1220	1220-1140=80
1991	1270	1270-1120=50
1992	825	825-1270=-445
1993	1150	1150-825=325
1994	1025	1025-1150=-125
1995	1143	1143-1025=118
1996	1280	1280-1143=137
1997	1093	1093-1280=-187
1998	1300	1300-1093=207

Describe the overall pattern(s) of the change in the glacier.  Make sure to relate the change in the equilibrium line to potential changes in the zone of ablation and accumulation

A glacier is a mass accumulation of snow that has been transformed in to ice. It is a solid crystalline material that changes and moves by advancing and retreating (Paterson, 2016). In scenarios where more ice and snow are accumulated than it is lost, glacier advancement occurs. However, if the rate of ice loss is higher than the rate of addition, then glaciers will retreat. Glazier zone of accumulation is the point where slow is added to glacier causing it to be converted in to ice.

The pattern of change in glacier as illustrated in the diagram above indicates seasonality. Seasonal factors such as changes in temperature caused advancement and retreat of glaciers. Generally, higher temperature lead to melting of ice and snow which leads to retreat of glacier through a process known as ablation (Benn & Evans, 2014) . Other agents of ablation include surface meltwater runoff, sublimation, windblown snow and avalanching. In contrast, low temperatures cause freezing of vapor which result to formation and scattering of more glaziers, a phenomenon known as advancement. Negative change in equilibrium line occurs when equilibrium line moves upwards as a result of addition of more mass to the glazier than mass lost due to upward movement of zone of ablation. Positive mass balance happens when glazier gains more weight than that which is lost leading to accumulation.

What are some local or global factors that might have produced the observed changes in the glacier

The movement of glaciers through advancement and retreat is caused by both local and global factors. Advancement and recession of glaciers lead to change in volume and length (Hutter, 2017). The movements are caused by variation in solar radiation, volcanic activities, and earth quakes. Rise in air temperatures influence rate of melting and contracting which lead to decline in mass of glaciers. Rising temperatures modify precipitation volumes and snow fall which increase ablation rates.

References

Benn, D., & Evans, D. J. (2014). Glaciers and glaciation. Routledge.

Hutter, K. (2017). Theoretical glaciology: material science of ice and the mechanics of glaciers and ice sheets (Vol. 1). Springer.

Paterson, W. S. B. (2016). The physics of glaciers. Elsevier.

Veblen, T. T., Young, K. R., & Orme, A. R. (Eds.). (2015). The physical geography of South America. Oxford University Press.