## Groundwater Resources Balance Calculation

For quantification of the climate elements impacts on groundwater resources their balance parameters have been analyzed. Because of various formation conditions of the fractured and fluvial aquifers, their balance structures are also different. The most complete balance approach for the estimation is the equation of water balance, where the groundwater run-off is taken into account. This is giving possibility to assess the basic part of annual renewable groundwater resources and symbolically it is stated as:

where, P: atmospheric precipitation, R: river run-off, S: surface flow, U: groundwater run-off, E: evaporation, and W: gross soil-moisture.

The preponderance of groundwater recharge compared with evaporation or vice versa is characterized by the recharge coefficients of Cr and Ce which are symbolically stated as Cr=U/W and Ce=E/W, subjected to Cr+Ce = 1. These coefficients offer a clearer view about the general water balance structure within the mountainous zones.

For quantification of the fractured bedrock aquifers, water resources of the mountainous regions, the upper groundwater stream (free water exchange zone and at the same time the underground component of river runoff) and the lower ground-water stream (difficult water exchange zone) are treated separately.

Estimation of the underground component of river runoff is performed based on the method of separation of the river flow hydrograph. The quantitative assessment of the water exchange zone was computed using the following formula:

where; Wo is deep groundwater run-off, Xo is atmospheric precipitation, Yo is surface flow, Zo is evaporation, and Ko is condensation.

The formation of the FGWR in the foothill and intermountain plains aquifers is a result of an infiltration from the atmospheric precipitation (Qp+), condensation (Qc +), river run-off (Qr +), and the rate of inflow along the valleys of mountain rivers (Qrv +) and from the foothill bedrock aquifers (Qd+). The natural groundwa-ter outflow elements are as follows: spring stream (Qs -), evapotranspiration (Qet -), groundwater drainage into rivers (Qdr -) and regional drainage basins - river or sea

Table 13.1 The natural fresh groundwater balance of mountainous regions and foothill plains in Azerbaijan

Inflow

Outflow

Elements

Percentage from total quantity

Elements

Infiltration from precipitation 83

Infiltration from condensation 17 waters

Total

100%

Groundwater discharge into rivers (local groundwater run-off) Deep groundwater run-off

Evapotranspiration Total

Elements of the groundwater balance for the foothill plains

Infiltration from precipitation 24 Infiltration from condensation 9 waters

Infiltration from rivers' water 32

Groundwater inflow from the 35 mountainous regions

Total 100%

Groundwater outflow Evapotraspiration

Groundwater drainage into the rivers' valleys

Total

Percentage from total quantity

Elements of the groundwater balance for the mountainous regions

100%

43 32

100%

(Qrs-), outflow from foothill and intermountain plains (Qoo -). Thus, the general natural groundwater balance can be expressed as:

Qp+ + Qc+ + Qr + + Qrv+ + Qd+ = Qs- + Qet- + Qdr- + Qrs- + Qoo- + Qv (13.3)

Qv here is a variation of the groundwater natural resources within the limits of the plans. In the long-term Qv tends to zero. The results of the general water -balance calculations of the FGWR are shown in Table 13.1. The presented results are showing that the all groundwater balance elements are derivative of a precipitation and directly related to precipitation. Climate conditions play special role in formation of the potable water resources.

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